Space Solar Power – Recent Conceptual Progress
Posted by Gail the Actuary on June 3, 2011 - 11:00am
This is a guest post by Keith Henson. Keith can be reached at hkeithhenson at gmail dot com.
Power satellites are an idea that has been around since the late 1960s [1] but not developed commercially because we don't know how to build an inexpensive space transport system. That may have changed recently, at least in theory.
We have known for decades that solar power satellites can send energy to the earth. Communication satellites do it every day, just not at levels useful for power. Power satellites scale to humanity's need; a calculation by G. Harry Stein back in the 1980s noted that there was room for 177 TW in geosynchronous orbit (more than ten times current energy use).
The concept is to make electric power in space (thermal or photovoltaic [2]), turn the power into microwaves, beam the microwaves to Earth and convert them back to electric power at "rectennas." The rectennas are simple (though large) structures that stop so little sunlight that the intention is to place them over farmland within a few hundred km of cities.
The biggest obstacle to solar power satellites is the cost of putting the necessary hardware in space.[3] There have been several previous discussions [4] [5] [6] about solar power satellites on The Oil Drum. What this current post does is describe a way to reduce the cost of putting the materials into space far enough that energy from power satellites can compete with coal (2 cents per kWh), assuming we amortize the total cost over a 10-year period.
Introduction
Power satellites convert sunlight (via photovoltaic or thermal cycle) to electrical power and then turn the power into microwaves beamed to the ground and converted back to electrical power.
Power satellites are a way of harvesting dilute solar energy with several advantages over the solar PV on the ground or rooftops:
- A system of power satellites scales to human civilization's needs (tens of TW).
- They don't need storage since their location (the 24 hour orbit, geosynchronous or GEO) is illuminated 99% of the time. [7] (Satellite TV antennas point to a location on that orbit.)
- No day-night cycle and no clouds or air gives power satellites an average advantage of about nine times over the same area of solar collectors on the ground.
- Power satellites use relatively little material. Being in orbit (zero gravity), and no wind they can be much lighter per kW than collecting sunlight on the ground.
- They have a very short energy payback time.
They have some disadvantages, however:
- For optical reasons, they don't scale down to small sizes; 5 GW is about as small as you want to make one. [8]
- At 50% loss electricity-in space to electricity-on-the-ground, the cost is doubled from one cent per kWh to two. On the other hand, that's 40 times less cost than transmitting the same power over wires for the same distance.
- They take a large investment to get the cost of transporting parts to GEO down to where they make economic sense.
Cost Requirements to make Space Solar Power Economical
Is a space solar project worth doing? We need to run a cost/benefit analysis to find out.
For a ten-year return on capital, a kW of power sold for a penny a kWh generates $800 of revenue (~80,000 revenue-hours in ten years). Two cents per kWh is about the most power could sell for to displace coal. That means a kW of power satellite capacity can't cost more than $1600 or $1.6 B per GW if it is to meet this goal.
If power satellites take 5 kg of parts to generate a kW on the ground,[9]and the transport fraction is ~1/3, then the cost to lift parts to GEO can be no more than $100/kg. That's a reduction of 200 to one ($20,000 per kg down to $100) over current cost to deliver communication satellites to GEO.
Hiroshi Yoshida, Chief Executive Officer of Excalibur KK, a Tokyo-based space and defense-policy consulting company, and William Maness, chief executive officer of Everett, Wash.-based PowerSat Corp., both think it will take this kind of transport cost reduction for power satellites to be competitive with other power sources.[10] [11]
Conventional Rockets
Can we get to this lift cost with conventional rockets?
Unfortunately, the answer is no, for several reasons. The chemical energy in rocket fuel vs. the required energy it takes to get to orbit is not enough. Rocket technology with chemical fuels has reached the performance limit. The most promising design is the Falcon Heavy (a proposal of SpaceX), with first launch intended for 2012 at a cost of $100 M per trip. The rocket is expected to put 53 tons in low earth orbit (190 km) above the earth’s surface, or 19.5 tons in geostationary orbit at 36,000 km. That is a reduction to $4000/kg, a factor of five below current rockets, but not enough. Launching a Falcon Heavy every hour might get the price down to $1000/kg, which is still too high by a factor of ten.
Reaction Engine has a developed a rocket plane called Skylon that is intended to be an improvement over conventional rockets.
Reaction Engine's study of Skylon indicates it will put 12 tons in LEO or (with a second stage) 5 tons in GEO for an estimated cost of $1.5 M or $300/kg. The project goal is to develop an unpiloted space plane that can be re-used up to 200-500 times. The expected cost per kg depends on the flight rate per year:
Unfortunately the cost is still too high by a factor of three. And it takes a flight rate of several per hour to get the cost that low. Are we out of luck and solar energy will stream past the earth forever? Not necessarily.
Skylon Sub Orbital plus Laser Propulsion
The new concept presented here is to use the Skylon sub orbital maximum load of 30 tons for a second stage (see Appendix: Into Orbit—Sideways below, also Wikipedia-Multistage Rocket). The second stage propulsion would be hydrogen heated to 3000 deg K[12] by a (relatively small) 500 MW array of ground-based lasers.[13]
The system with ground-based lasers would function as follows:
- The laser beams go up to an array of tracking mirrors in geosynchronous orbit over a point 3500 km to the east of where the second stage release point.
- The ground lasers point at the bounce mirrors which track the accelerating laser powered second stage over 11 degrees. (The mirrors move 5.5 degrees in 16 minutes.)
- Hydrogen at 3000 deg K gives the second stage ~10km/s exhaust velocity. This velocity is about twice the required delta V for a mass ratio of ~1.65.
In this system,18-20 tons of 30 will arrive at GEO per flight. The capital cost for the lasers ($5 B or $500 M/year) is about $1/kg when spread over 480,000 tons of cargo per year and it drives the lift cost for parts down to $100/kg. In maximum payload sub orbital mode, Skylon is projected to boost a 30-ton payload to 157 km apogee and 6966 m/s. See page 10 from this manual.
To avoid excessive aerodynamic heating, the payload release is delayed to 135 km. Unpowered, the payload would take 150 seconds to reach apogee. A velocity of 6966 m/s is ~1000 m/s short of LEO and 3286 m/s short of geosynchronous transfer orbit (GTO). [14]
An acceleration of more than two m/s2has enough time to put the second stage into orbit. The second stage loses upward velocity slowly because the effective g at 87% of orbital speed is low, around two m/s2. Under light acceleration (see below graph), the second stage gets to orbital velocity before it runs out of upward motion.
There are limits on how long and how slow the second stage can be accelerated with a laser. The vehicle has to stay in view of the bounce mirror in GEO and it has to exceed orbital speed before it falls back into the atmosphere.
The normal metric for laser launch from the ground is around a GW per ton of payload. If you need a cargo size of 20 tons (about the minimum for power satellites) that means 20 GW of laser, drawing 40 GW off the grid and costing perhaps $200 B. This is partly because the very high exhaust velocity of laser propulsion is energy inefficient until the vehicle is up to a velocity comparable to the exhaust velocity and partly due to the short time the vehicle is in view of a ground laser. The following are some ways the cost might possibly be reduced:
- Bounce mirrors, for all the complications of being in GEO and having to track the vehicle, reduce the amount of laser power needed for 20-ton payload to GEO by a factor of 50. They do this by allowing an acceleration of less than one g and by permitting the laser to be on target for roughly 4 times as long as is practical for a ground up launch. (See Figure 5 below.)
- It does require a chemical rocket or rocket plane boost to near orbital velocity but from 50% to 150% their exhaust velocity is where chemical rockets work most efficiently. (See http://en.wikipedia.org/wiki/File:PropulsiveEfficiency.svg.) Up to the end of using air at 26 km and two km/sec (44% of Skylon's rocket mode exhaust velocity) aerospace planes in air breathing mode are very efficient.
- Geosynchronous transfer orbit velocity is 10252 m/s. Circularizing the orbit at GEO requires an additional 1630 m/s for a total delta V from the ground of 11,682 m/s. The exhaust velocity for hydrogen is roughly 9800 * sqrt (T/3000) where T is degrees K
- Together, the extra delta V is 4916 m/s for the second stage--which is about half the exhaust velocity leading to a mass ratio of ~1.65 for the mission or 10-12 tons of reaction mass for 18-20 tons of payload and vehicle. Expending most of the reaction mass low in the earth's gravitational field leads to slightly better performance.
- In various designs, I have used both constant acceleration and constant heater temperature. Constant heater temperature provides higher exhaust velocity and better exhaust velocity performance if it provides enough acceleration to get the vehicle into orbit before it falls into the atmosphere or goes out of view.
- Together the accelerations to GTO and the circularization burn at GTO can't take more than 20 minutes to get a transfer rate of three flights per hour. 10,000 kg of hydrogen over 1200 seconds is 8.33 kg/sec
- The laser power required comes from 8.33 kg/s accelerated to 9.8 km/s. Ke/s = 1/2 mV^2/s, where m is 8.333 kg/sec and V is 9.8 km/ sec--solving, 400 MW.
- There will be some atmospheric and optical loss for the laser beam and some re radiation loss from the vehicle. These should be relatively small (under 20%), raising the laser output to 500 MW and the input (at 50% efficient) to 1 GW.
- The flow of 8.33 kg/s of hydrogen and 400 MW (after loses) results in a constant heater temperature of 3000 deg K (for an exhaust velocity of 9.8 km/s) and an initial acceleration of 2.72 m/s2.
This is an unusual regime for rockets. It is between the low exhaust velocity/high thrust of first stage rockets and the low thrust and very high exhaust velocity of ion drives.
Under these conditions, a second by second spreadsheet analysis shows that a 30 ton second stage vehicle enters GTO downrange 7743 km at 970 seconds with 21,900 kg of mass remaining. Because thrust is constant as mass is used up, the acceleration climbs to 3.727 m/s2 (under 0.4 g). It takes until 1206 seconds to reach the velocity required for GEO insertion, i.e., a second burn 5 or 15 hours later of 236 seconds. For a first pass analysis, this is close enough to 20 minutes.
The peak acceleration at the end of circularizing at GEO is just over four m/s2 (all really low accelerations). According to the spreadsheet, there is almost 20,000 kg (19937 kg) left. I.e., ~20 tons gets to GEO per Skylon flight. We are assuming that everything going to GEO becomes power satellites (even the sandwich wrappers for 500 workers at GEO).[15]
Cost Reduction Details
Conventional use of Skylon will deliver about 5 tons per flight to GEO. For a three per hour flight rate, that's 15 tons per hour. By adding $5 B of lasers (and the GEO bounce mirrors), laser boosting a sub orbital payload will put 60 tons per hr in GEO, that is, 4 times as much. In calculating the economics the following assumptions are made:
- Operating this transport system 90% of the time, it lifts 8000 h/yr x 60 t/h or 480,000 t per year. (That would support a substantial power satellite production.)
- At 5000 t/GW, it would make 96 GW per year (19 five GW power satellites).
- At a price of $1.6 B/GW (2 cents per kWh paid off over ten years), the revenue stream from selling power satellites would be over $150 B per year.
To put the addition of laser powered second stages in context, the same flight rate would allow four times as much cargo to GEO for the same cost in Skylon launches. The capital cost for the lasers ($500 M/year expensed at 10%/year) is about $1/kg when spread over 480,000 tons of cargo per year and it drives the lift cost for parts down to under $100/kg. The cost to GEO (not LEO) would come down to under $100/kg, which is the magic number for two cent per kWh power, i.e., half the price of coal (or less). [16]
Power Satellite Energy Economics
While Energy returned on energy invested (EROEI) is good metric for sources such as oil, coal, and natural gas, which have reserves that are eventually exhausted, the Wikipedia article for Net Energy Gain (NEG) indicates that NEG or payback period might be a better metric for sustainables. According to the article:
The situation is different with sustainable energy sources, such as hydroelectric, wind, solar, and geothermal energy sources, because there is no bulk reserve to account for (other than the Sun's lifetime), but the energy continuously trickles, so only the energy required for extraction is considered.
In all energy extraction cases, the life cycle of the energy-extraction device is crucial for the NEG-ratio. If an extraction device is defunct after 10 years, its NEG will be significantly lower than if it operates for 30 years. Therefore, the energy payback time (sometimes referred to as energy amortization) can be used instead, which is the time, usually given in years, a plant must operate until the running NEG becomes positive (i.e. until the amount of energy needed for the plant infrastructure has been harvested from the plant).
For photovoltaic cells, the NEG of their production depends on the operating lifetime, and the amount of sunlight available in the operating location. Today the break-even energy payback time (the amount of time required to produce an amount of energy equal to that originally used to manufacture the array) is around two to four years, compared to an effective production life of over 20 to 30 years (e.g. many manufacturers now provide a 25-year warranty on their products).
Note the in the last paragraph quoted above indicates that the energy payback period for solar cells is two to four years. The corresponding payback period for wind is given by Renewable UK:
The average wind farm in the UK will pay back the energy used in its manufacture within six to eight months.
The payback time for wind farms doesn't include the backup gas turbines for when there is no wind, nor the energy required for long distance transmission lines to distribute the wind energy to cities far from the production source.
So how do solar power satellites stack up?
Aluminum is the most expensive construction material in terms of releasing it from the oxide and it's less (13 kWh/kg) than the least possible energy investment to get it to GEO (15 kWh/kg). Since the projected transport energy cost are many times more than the energy in aluminum, we can usually ignore of the energy investment in parts for power satellites to make a rough calculation of energy payback time.
A hypothetical moving loop space elevator would require the minimum energy needed to get payload to GEO. For a power satellite made with parts brought up by a minimum energy space elevator, 5 kg (enough for a kW) will take 75 kWh to lift it to GEO. The energy payback time is just over 3 days (6 days if you count the ~75 kWh needed to make aluminum.)
Alas! We don't have and may never get space elevators. What about other ways to get parts to GEO?
- Chemical rockets are around 2.5% energy efficient so the payback time is 40 times that long or about 120 days. That doesn't include the relatively large amounts of energy needed to make the rocket structure, though.
- For the highly reusable Skylon and laser proposal, the laser part, draws around a GW to send 60 t/h to GEO(starting from a sub orbital boost by the Skylon). It also uses 30 ton per hour of hydrogen with an energy content of 210,000 kWh. One million, two hundred and ten kWh/60,000kg is 21 kWh/kg.
- The Skylon boost phase burns 66807 kg of hydrogen per launch; the energy in the hydrogen (at 70 kWh/kg) for three per hour would be 14,029,470 kWh, / 60,000 kg or 233 kWh/kg.
- Together, 254 kWh/kg, (6% efficient compared to the minimum energy) so material for a kW of power satellite would take 1270 kWh to lift--which gives an energy payback time of around 53 days, under two months.
This is substantially shorter payback time than ground solar or wind.
So at least from the physics of rocket planes, laser propulsion, and the energy economics of power satellites, it seems to be possible to have a world with plenty of low cost energy.
This is by no means a fully worked out proposal. For example, how do we get sub orbital Skylons back to their runway? Can we really heat hydrogen with a laser to 3000 deg K? That is 600 deg below melting tungsten but questionable. Carbon is a solid up to 3900 deg K, but at that temperature will it become hydrocarbons?
More analysis might find the entire project to profitability as low as $40 B (half for Skylon development). If that's the case, it's close to the Chunnel or Three Gorges Dam in current dollars.
***********
Appendix: Into Orbit—Sideways
Here's a very rough design of a laser powered second stage to GEO to go with the C1 Skylon.
- The Skylon payload bay is 4.8 across x 13 meters or 62.4 m2. For 400 MW, that is 6.4 MW/m2or 640 W/cm2. That is a lot of heat to be absorbed in a small area, but less than 3 times that of a commercial heat gun per square cm.
- Because we want the laser absorber accurately pointed at the laser beam coming down from geosynchronous orbit the idea would be to put nozzles on each end of a drum shaped vehicle--which would fly sideways into orbit. It would feed 3000 deg K hot hydrogen through a plus or minus 6-degree rotating joint to keep the absorber pointed at the laser beam. Such joints exist on solid rockets.
- The volume of the payload bay is ~ 15 m2 x 13 m or 195 cubic meters. The second stage hydrogen tank (10,000 kg) would occupy 143 cubic meters, leaving 52 cubic meters for 20 tons of heat absorber, tanks, rocket nozzles, pumps and cargo.
The 8.3 kg/s flow of hydrogen needs to be at 5-10 bar. Jordin Kare's micro channel heater design is one approach. Another that would reduce re radiation would be to use a curved piece of transparent aluminum oxide with a cavity light absorber under it (co-flow per http://www.freepatentsonline.com/4033118.pdf). Cold, flowing hydrogen would carry away any energy deposited in the window material.
Ten bar of pressure is a million Pascal. The hoop stress for 4.8 m diameter is 2.4 M N per meter. Tensile for fused aluminum oxide is around 360 M Pa, used at 240 M Pa, it would be one cm thick. The window mass would be around 5 x 13 x .01 x 4000 kg per cubic meter or 2600 kg (or 1300 kg for five bar).
This is OK since everything that gets to GEO becomes parts for power satellites. If you can't use it for anything else, grind it to dust and use it for heat sink pseudo fluid (low pressure gas and fine solids blown around in giant rubberized fabric tubes).
The laser heat absorbers would be useful parts in thermal type power satellites, perhaps down rated to 100 MW. With some thought to the design, much of the second stage pumps and other parts may be useful for constructing power satellites.
References
[1] Invented by Dr. Peter Glaser of Arthur D. Little.
[2] The author favors thermal designs. A 60% efficient thermal cycle power satellite requires only 1/4 of the sunlight inception area of a 15% efficient photovoltaic (PV) system. It does take large radiators, but the area of the concentrator and radiator is still smaller than the PV area.
[3] There have been proposals since the mid 1970s to build power satellites out of asteroids or lunar rock. Eventually, I expect that to happen, though not before hundreds or thousands of power satellites exist.
[5] Space Solar Power: Star Player on the Bench
[6] Solar Satellite Power with Laser Propulsion and Reusable Launch Vehicle
[7] They go, one at a time, into the Earth's shadow for up to 70 minutes around the spring and fall equinoxes. It's a time of low power demand, and they take turns being out of service.
[8] This is for 2.45 GHz. Smaller sizes are possible with smaller wavelengths, but loses in the atmosphere becomes serious.
[9] Solaren has proposed a design that is 85 times less massive than five kg/kW.
[10] http://www.bloomberg.com/apps/news?pid=20601101&sid=aJ529lsdk9HI
[12] Based on Laser propulsion
[13] Based on these as monochromatic pumps. Applications of laser diodes
[14] GTO Geosynchronous transfer orbit, a ten-hour elliptical orbit that touches LEO and GEO. See Hohmann transfer orbit
[15] This number is scaled on the productivity in tons per person per day used to build Liberty ships in WW II and a modest improvement since then in productivity. The worker housing and support cost to keep 500 people in GEO is nearly trivial in the context of a program this large. Ten kg per person per day is 5 tons in a power satellite parts stream of 1440 t per day or 0.35%. Further, any waste, including excreta, becomes part of a power satellite(gravity gradient ballast if nothing else.)
[16] With cost to GEO at $100/kg and 5 kg/kW, the parts and labor no more than $900/kW and the rectenna at $200/kW, the levelized capital cost would be from 15.3 to 27.8 dollars per MWh depending on the discount rate with the lower being at 5% and the higher being at 15%.
Given that communication satellites last 20 year with no maintenance, it is hard to see why O&M in space should be as high as 1 percent of investment per year, but using that, $2 a MWh. No charge for fuel and same as coal for transmission gives a levelized cost of space based solar power of $18 to $31 per MWh. That is 1.8 cents per kWh to 3.1 cents per kWh.
At worst, it is less than 1/3rd of the cost of power from coal and under half of the least expensive power from gas.
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Thanks, Gail and Keith. Interesting stuff. I have no doubt that, given enough time/resources/money, humans will become more efficient at 'liberating' matter from Earth's gravity well.
My question is, were someone successful in actually deploying such a contraption, what would be the unintended consequences of punching gigawatts of highly concentrated microwaves through the atmosphere? We human's are quite good at that, the art of creating unintended consequences I mean.
It occurs to me that we may be better served launching and deploying a few hundred million square kilometers of shade cloth at this point.
The existing designs are not particularly concentrated, around 1/4 of sunlight. The only reason they make sense over solar cells is that the rectenna is really low cost and it gets power 24 hours a day. I think the power could be pushed up some without disturbing the ionosphere or even better the microwave beam could be shaped into a "top hat" profile to reduce the size of the rectennas.
If you are talking about intercepting sunlight at L1, then low cost transport is even more important.
Excellent post, Gail & Keith, thank you.
It is hard to appreciate the energy economics of SSP without some careful comparisons with existing energy alternatives; A few -
> Under "Power Satellite Energy Economics", Keith notes that the energy payback period to manufacture photovoltaics (PV) solar cells is two to four years". Note that the wikipedia NEG calculation cited is for industry standard mono-crystalline silicon cells gathering energy on the ground. At GEO however, thin-film cells would likely be used. Thin-film PV is just one hundredth as thick (and heavy) as standard PV and requires just one hundredth as much energy per unit area to manufacture. Since PV at GEO would collect nine times more energy per square meter per day, as Keith earlier noted, you can repay that "energy debt" 900 times faster with SSP PV compared with standard ground PV.
> SSP would be built and then serviced continuously via telerobotics which would be engaged in replacing and repairing damage from micrometeorites chiefly. An SSP would also be well defended principally against larger small meteor and debris fragments that threaten the large gossamer and other harder structures. Nuclear power plants and other major infrastructure for example, are also similarly well defended.
> A Sunsat Corp would be interested in low cost space transportation, only as a bulk purchase customer, as Solaren is today or Japan's $2 Trillion yen SSP consortium. Most orbital space transportation companies are well aware of the massive change to their business models which will take place as the volume of freight to orbit grows rapidly a hundred fold to tens of thousands of flights per year and beyond. Major airports, such as Chicago and Atlanta, already do a million flights per year, each burning similar amounts of fuel. Electric launch for the first stage will rapidly follow, as the Navy's EMALS has already been demonstrated and shipped. Waste heat is not the real problem, though. An SSP rectenna would contribute a small fraction as much waste heat as same-sized existing coal, gas or nuclear plants. The real issue is CO2 when you start examining heat entrapment. An SSP antenna on the ground would contribute about 30 grams of CO2 per kWh generated - the same as wind mills. Coal generates about 976 grams of CO2 per kWh.
> Water use is the sleeping giant in energy generation. Again SSP dominates, using nearly no water in operation. A standard baseload coal power plant withdraws 25,000 gallons a month to provide power to one house. 31,000 if nuclear. It takes 9,100 liters of water to make one liter of biodiesel fuel.
Great post, Keith, thank you. It IS a challenge to well understand the energy transformation ahead, but there is no better choice than SSP; the future is bright once we carefully examine this high frontier alternative.
Space Solar Power Workshop
Space Solar Power Institute
Space Solar High
National Space Society
Thanks for the comments Darel.
I only described power satellites at the block diagram level because the big problem as I see it is the high volume, low cost transport to GEO.
There the name of the game is high average ISP or exhaust velocity.
Skylon does that by operating as an aircraft part way up, Jordin Kare's laser proposals do that by extremely hot hydrogen.
It surprised me when I ran the analysis of how short the energy payback was.
I know there isn't much money for power satellite design work, but the next time it comes up, I hope people will look into thermal designs. Jet engines are already at 10kW/kg, concentrators are very light and damage resistant, and low pressure radiators filled with fine dust are not very heavy per kW radiated.
My main reason for proposing people is that they exist and telerobotics devices don't yet. Whatever works.
Water use is the sleeping giant in energy generation. Again SSP dominates, using nearly no water in operation. A standard baseload coal power plant withdraws 25,000 gallons a month to provide power to one house. 31,000 if nuclear. It takes 9,100 liters of water to make one liter of biodiesel fuel.
?? Not that this is central to the discussion of the space power system, but where did you get these numbers from? They are way off the mark.
For the the typical "house" - 1000kWh/month, a coal fired plant will consume (=evaporate) 450gal, or about 1/50th of your number
[source, p9 of this NETL 2010 report]
I expect nuclear to be similar.
And for biodiesel, if that number were true, an field of canola would need an annual rainfall of 15 feet!
Since the space system is theoretical, we expect some latitude in numbers, but the numbers are well know for terrestrial stuff.
The biodiesel data is from a McKinsey report in NYTimes
http://green.blogs.nytimes.com/2009/11/23/report-warns-of-rising-water-d...
What is your biodiesel data source, Paul?
Your own water use source, "Water Vulnerabilities for Existing Coal-fired Power Plants", agrees with the figure I stated, Paul, as you know. You just emphasized the "use" column rather than the "withdrawn" column. My data source is "Energy Risk – Sinking Water and Rising Tensions", by Ken Silverstein, Editor-in-Chief, http://www.riskcenter.com/story.php?id=15710
I can send you a copy if you like, since RiskCenter membership is required for archive access.
Water temperatures impact on fish, closed loop cooling cost & inefficiencies, falling water tables, drought etc., are all vital water-related issues. Broad issues from fracking to Hoover Dam/Lake Mead levels continue to escalate the energy, environment and economy "water wars".
So for those of us without access to the proprietary sources who want to understand: very simply, are you actually claiming, based on your source, that a field of canola actually requires the equivalent of fifteen feet of rainfall, far more than almost any rice paddy gets? Or can you paint some other plausible, basic picture of where all that water would be going, that doesn't require a Ph.D. to comprehend? When the numbers are far too high to believe, I tend not to believe them unless someone can make them plausible.
What is your biodiesel data source
I used back of the envelope numbers for canola farming, (yield and rainfall) but lets use official numbers here;
We can get information on moisture requirements for canola growing from the Canola Council of Canada.
Table 2. Average Effects of Water on Yield Components and Yield of B. napus - Outlook, SK Area
Water Use Seed Yield
mm kg/ha
Rain fed 210 922
Low irrigation 282 1,537
High irrigation 369 2,463
So, 369 mm over one ha is 3690 cu.m/ water, and yields 2463kg, or 1.5 cu.m/kg of canola seed. It is still a lot of water for a small amount of product, but that's true of any plant system.
The canola council report current oil yields of 42.8% by weight,m so we get 1054 kg of oil per ha. The oil press cake is a high protein food product in itself,( which actually substitutes for 2kg of barley for cattle feed). We allocate 57.2% of water to the feed cake, so the oil represents 42.8% of the 3690 cu.m, or 1580 cu.m.
Finally, the oil has a specific gravity of 0.88, so 1054 kg yields 1198L of oil.
So we have 1,580,00L of water for 1198L of oil, or 1320 L water for one litre of oil.
Your report was 9100L, which is 6.9x the water use. So multiplying our 369mm by 6.9 we have 2550mm, or 7.7feet of rainfall.
So, my original estimate was double - that was using an annual average rainfall of 600mm - but not all of that is used by the plants in the growing season. Shows how much the numbers make a difference
By extension, we can also estimate other useful things like water used for wheat growing. Assuming the same field water and typical yields of 3t/ha, we have 3,690,000/3000kg = 1230L/kg wheat. A half kg loaf of bread contains about 1/3kg wheat, so we have 410L of water for a loaf of bread!
Fact is, everything uses lots of water, makes the 4 barrels of water for a barrel of oilsands oil look like a bargain
For the coal, You just emphasized the "use" column rather than the "withdrawn" column.
That is correct, the "unused" water is available for "re-use". For example, I could use it to grow canola and make biodiesel. By your accounting, since you deem it al to be "used" by the coal plant, it is then taking me zero litres of water to grow canola, and that just ain't the case.
Alternatively, you could have cascading coal plants using the same water stream. The first one evaps 5%, so the next has 95% available, it evaps another 5% , so the next one has 90.25% available and so on. By your method we are increasing the water use efficiency 100% with each subsequent plant - but this is wrong. What matters is how much water is no longer available for something else, or return to the environment.
Tailwater from a thermal plant is warmer than ambient for sure, but let it sit for a day or two and it will cool down - it'll still grow canola just fine.
A city withdraws X water from a river, and usually returns about 0.7X as sewage effluent. This water, is available for re-use - it has not been consumed (evaporated).
Water that is evaporated is lost, but water that is still present as water is not - that's what counts.
Thanks, Gail and Keith. Interesting stuff.
But pie in the sky technofixes are still Bulls*smack*hit.
As noted here - the power density of land based PV is greater than 1/2 of proposed beamed down power.
http://www.theoildrum.com/node/5306#comment-494573
As noted - a whole lotta effort for LESS than 1/2 the gain of putting PV on land.
My question is, were someone successful in actually deploying such a contraption, what would be the unintended consequences of punching gigawatts of highly concentrated microwaves through the atmosphere?
Theories about this exist with the people who track HAARP.
But space is already filled with space-junk. And the amount of space-junk is already a threat to things in orbit. And when Earth drifts through a cloud of small rocks the platforms will be ripped apart into a cloud of space junk thus keeping Mankind bound to Earth until enough energy exists on Earth to clear out the junk *OR* many generations of Man come and go thus allowing the space junk to de-orbit.
But hey, like the Fukishima reactor is showing with great quotes like "No one could have anticipated a Tsunami like that" I'm sure if the space based power boondoggle gets built and then tore apart via interstellar clouds of debris the quotes of "No one could have anticipated small rocks in space" will be the catchphrase of the day.
Space Based Power was a bad plan when posted on TOD a couple of years ago by the same group, it is still a bad plan now.
Is this consistent with three lines up?
Re space junk, 500 MW of lasers, even CW lasers, will clean it all up in weeks. Probably the first use of the lasers and mirrors.
I'm sorry - are you responding to ME or the other poster I quoted?
I'll note how you did not address what I posted - so do you accept the statements as true?
I'm not Keith, but I certainly don't accept the statements as true. 25% of the intensity of sunlight means 250 watts per square meter, at 85% microwave to electricity conversion efficiency, times yearly average of 23.75 hours per day, gives 5.04 kWh per square per day for rectenna.
For terrestrial PV, it's 1000 watts per square meter times 20% light to electricity conversion (being generous), times 6 hours per day equivalent for tracking panels in a good location, giving 3.0 kWh per square meter of PV panel. And the tracking PV panels have much higher per-area cost, much higher environmental impact (no dual-use possibility for collector areas) and require expensive energy storage facilities (or dispatchable fossil-fueled power) to address intermittency.
My data came from the website noted.
Where's the links to your data sources?
(Not to mention the on land solar PV is still greater better than 1/2 the 'toss stuff into space' as I've noted in your "no you are wrong" position.)
And how does this "on land solar PV" perform for base-load supply, and can you grow anything under it?
The numbers you're getting wrong have been in public sources since the 1970's. You're not using reason here (and insulting the memory of the author whose name you misappropriate).
how does this "on land solar PV" perform for base-load supply
FWIW, intermittency isn't PV's primary problem, cost is. Of course, there is the night problem - I think wind power (and probably nuclear) are likely to be more important for a very long time.
My "data" came from a well-known constants and a calculator. Except that I blew it on the PV output. 1 kw / m^2 x 20% conversion x 6 hrs / day for tracking panels in a good location is 1.2 kWhr / day for terrestrial solar. Not 3.0. Also, the land multiplier for tracking panels is at least 4:1 to avoid excessive shadowing. So the land advantage for SSP vs. terrestrial solar ranges from about 5:1 up to 20:1; or more, depending on what you're counting and the characteristics of the terrestrial solar location.
Theory is great.. in theory. It's still vaporware.
The number and scope of things that could go not just wrong, but spectacularly wrong means this whole conversation is arguing about how many angels can fit on the head of a pin.. sound and fury in glorious insignificance.
Skylon is nice if you need to put important light payloads or humans. You need to realize that for safety you are paying huge price. If you want to deliver payload which can be easily replaced situation is quite different. Paying $20,000 per kilogram of human is adequate cause cost of human live is very high. If you want to reduce operation expenditures you will end developing expensive technology to achieve this which in turn would require huge amounts flights to pay back this investition. But do we need this reliability to deliver $100/kg of aluminum alloy strut? Is price of loosing this payload so high? What if we have launch system which can deliver payload to orbit for $1000 but with success rate of 33% percent? Wouldn't be this waste then economical? Problem with current space technology is that it evolved from military missiles. They have to be small ( for better protection in silos) and very reliable ( blowing nuclear warhead above own territory isn't very good). Price was neglected. This turned into very high $/kg. This turned into developing miniaturized expensive satellites which were very expensive. This required to build more expensive more reliable rockets....
There are also lower tech solutions how to get things in space http://www.optipoint.com/far/far8.htm http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29 http://www.optipoint.com/far/farbdb.htm
I am not particularly attached to Skylon, it's just the best I know about. If you have another way to get the cost to GEO down to $100, sounds good to me.
You can design rocketto transport people safely. You can desing system to transport cargo safely. When you try to combine this you need to compromise one of those above mentioned. There are another concepts for instance this:
http://www.thespacereview.com/article/544/1
http://www.astronautix.com/lvs/aquarius.htm
http://en.wikipedia.org/wiki/OTRAG_Rocket
http://www.astronautix.com/lvs/otrag.htm
I feel like I should mention that the #1 most likely way that this gets implemented is by the military. And not as a space age weapon (despite claims by SimCity 2000) as the intensity of the radiation (as mentioned above) is too low to be used that way. Rather, it provides a way to potentially send power to remote military bases without the need to convoy in thousands of trucks of petroleum through hostile territory. Those trucks are extremely expensive, and the US government (at least) has the willpower to pull something like this off if sufficiently motivated. For instance, there's no way that GPS was cost effective when first put up -- but the military didn't care, and now it's of great utility to the entire planet. Not to mention the advantages to most first world countries of reducing their dependence on foreign oil... I think that what, France is the closest to not being horribly blatant energy importers? With no one else even being remotely close to it. Energy security is national security after all.
I don't really think that space based power is the best idea ever, but it does have the advantages (as laid out by the huge report in the 90s) of providing terrorism resistant, 24-hour continuous, large scale, beamable power. Obviously, the countries with space programs (possibly including Iran and North Korea) could blow the array out of the sky in an act of war, but that's pretty risky for any sovereign state. It's obviously an act of war, it is obvious where the missile came from, and given the magnitude of the attack would likely be met with pretty serious retaliation. I doubt that a country like China or the USA would blow it up if it belonged to an enemy nation unless things were already so seriously f*cked that nuclear war was probably inevitable anyway.
Right!!! Let's build our society/civilization around an ultra complex system that is totally dependent upon everything working (and that includes society) for generations in a hostile environment; a system that can't even be repaired if any part of the system fails. Geeze, are people ever going to wise up? One final thought: How's it going to do in a CME even if we stupid humans did get such a system up there?
Todd
Our civilization is already mind bogglingly complex.
Re repairs, there would be high hundreds to thousands of people building power sats in GEO. If one needed service, I can see no reason they could not fix it. Plus you have hot spares.
Coronal mass ejections might be a problem from induced currents on PV power sats, but I can see no reason a thermal type would be bothered by a CME.
Hi Keith, are you aware of this possible alternative to GEO? You still get 24 hour sunlight and it's a much lower orbit.
http://www.earthspaceagency.org/space-articles/space-opinions/the-space-...
Coronal mass ejections might be a problem from induced currents on PV power sats, but I can see no reason a thermal type would be bothered by a CME.
Other than physics. If a mass strikes the space boondoggle it will react to that mass*speed force.
But hey, if you can't model a CME then just ignore it! That'll end well for Mankind.
Eric, please calm down. A Coronal Mass Ejection passing by will actually be a very high vaccuum, probably better than we can produce down here on earth. The force is negligible - it won't smash up satellites or send them careering into interstellar space.
Darwinian has stated the effects of the solar wind as
http://www.theoildrum.com/node/7898#comment-809206
A CME far exceeds 'a solar storm'.
An example from today of that excess.
http://blogs.discovermagazine.com/badastronomy/2011/06/07/the-sun-lets-l...
Before this set of comments I had never heard of the orbit of any satellite being disturbed by a CME.
They are certainly big enough, 1.6 x 10^12 kg and fast, up to 3200km/s. But by the time they reach earth orbit they are at least 1/10 of an AU in diameter. That an area of 1.77 x 10^20 square km, so the mass is about 1 x 10^-8 kg/km^2. Since MV = mv, a 25,000,000 kg ten square km satellite will gain velocity from being hit head on by a CME of 10 x 10-8 x 3.2 x 10^6 /2.5 x 10^8 or about 1.3 x 10^-9 m/sec
I think I will ignore it.
I think I will ignore it.
In the same way there is no response to the 300W/m2 for the microwave collection VS the 170W/m2 as noted here:
http://www.theoildrum.com/node/5306#comment-494573
Or the effects of micrometeorites on the space based boondoggle.
This is your front page post to convince TOD. Objections of micrometeorites and the not much better than normal land PV power collection rates have been raised. Are you going to just ignore these observations?
And as for:
I had never heard of the orbit of any satellite being disturbed by a CME.
Carrington event of 1859 lacks satellite data, so yes you are correct.
But no one has satellite data on what is a demonstrated effect.
Hey, slightly over a nanometer per second in an orbital velocity of 3 km/sec?
It's a matter of cost, and that's dependent on the amount of mass involved and how much energy it takes to build and install PV or rectennas. Plus the cost of storage. Plus the cost of transmission because the places with the most light are not near the big loads.
Get all of these cheap enough, down below $1600 per installed full time kW, and power satellites don't make economic sense. It hard though because of gravity, wind and the part time sunlight. Rectennas are on a par with chicken wire so they don't have a wind problem and light so the gravity problem is much reduced. They use silicon for the diodes, but it is way below 1% of a solar panel.
StratoSolar might get into that range. 20 km up they don't have problems with clouds so the solar flux is predictable. If you can get permission from the FAA, they can be relatively close to the loads. No cosine effect because you point the collector right at the sun. And heat storage in 35,000 cubic meters of fire brick (at 1400 C) cost about 1/10th cent per kWh in a GW sized plant. But coping with peak winds makes them an engineering nightmare.
Further out, nanotech based collectors that would grow all over roofs and wall for close to nothing would almost certainly be less expensive than power satellites. But who knows when that will come along?
A communication satellite subjected to that event might have the electronics burned out, but the orbit is not going to be disturbed enough to measure.
This comment reveals just how ignorant you are about things to do with space, CME's are, as Paul states, very hard vacuums, you may as well start panicking about Earth passing through the tail of a comet and everyone dieing from cyanide poisoning.
Hey, it's happened before!
http://en.wikipedia.org/wiki/Halley%27s_Comet#1910
Coronal Mass Ejections, 2012, Zombie Apocalypse, Chemtrails... all brought to you, massively, by Coast to Coast AM Radio in lieu of any real discussion of political, financial, technical, or human reality. The believers get all worked-up over these things.
http://www.disinfo.com/2011/02/warning-massive-solar-flare-about-to-impa...
There is a danger in putting all ones eggs in a single basket.
Can you say Credit Default Swaps?
Re Coronal Mass Ejections (http://en.wikipedia.org/wiki/Coronal_mass_ejection)
I can't find a real reference to 5kg/kW following your links,
but NASA has this 1.3 kg/kW scheme, BUT it assumes PV, not mechanical.
http://gltrs.grc.nasa.gov/cgi-bin/GLTRS/browse.pl?2004/TM-2004-212743.html
(see PDF within above). N.B. that minimum assumes a "supersynchronous" setup, orbiting at L2. Because of microwave aiming issues (as identified in the report), other schemes are heavier.
Because of vibration and/or torque, material fatique, maintenance ... issues - I doubt you'll be seeing thermal type solar powersats.
N.B. a major Stirling engine solar park has been re-designed as PV:
http://www.greentechmedia.com/articles/read/aes-709-mw-solar-thermal-pro...
But even a thermal type would have some controlling electronics, and they are vulnerable to space weather (build a nuclear plant in a fault/tsunami zone, build a space powersat in a space weather zone, ... sounds dubious).
Also, nobody has mentioned (that I see), that the large area metallic rectanna seems even more vulnerable to geomagnetic storms than transmission lines.
http://en.wikipedia.org/wiki/Geomagnetic_storm
It is very conceivable that one would have to rebuild some/all of the rectanna after the solar storm.
While much is made of the "it's not dispatchable...", ground based PV with a bit of battery comes closer to meeting the late afternoon peak demand. 24x7 PV in space would either need storage, or would dump electricity late at night due to the typical electrical demand pattern: low late at night, rising as people get up and go about their day, peaking in the summer late afternoon with air conditioning or late evening heating in winter, then falling as people go to bed.
see this on electrical demand timing, etc.:
http://thearchdruidreport.blogspot.com/2011/06/in-world-after-abundance....
see the demand/forecast/actual of California here:
http://www.caiso.com/outlook/outlook.html
As for the "hundreds to thousands of people" in GEO working on these, note that GEO has much higher levels of radiation (it's in the middle of the outer Van Allen belt), and less shielding from the magnetosphere.
During a severe space storm that includes solar energetic particles these astronauts will have radiation sickness or be dead if they are not ensconced in a very HEAVY/massive shielded chamber. N.B. "telepresence not here" - guess you did NOT spend all too many hours watching ROV footage during the Macondo well blowout....
Robots don't need food/water/oxygen/pressurization - stuff that needs to be hauled from the cool green hills of Earth.
With the mass budget available in power satellites, you can shield beyond the worst storm in the historical record.
Absolutely not. What causes the pseudo DC currents that saturate transformers is the moving magnetic field in loops that include the wires and a current path clear down to the mantle. Long wires (hundreds of km) and high resistivity surface rocks (so the current goes deep) are the elements that allow a geomagnetic storm to damage power transformers.
Rectennas are, by these standards, compact objects that don't have the large loop area.
See up thread about draining the Van Allen belt. Otherwise, these are very likely to be Chinese. There might well be 1000 of them. If radiation killed them all every two months, that would still be less than the 6000 plus the Chinese admit die in their coal mines.
Also see up thread and the article for how tiny a part of the parts flow resupply for humans would be.
That is close to being racist.
NAOM
I suppose it is. Given the current decline of the West, particularly the US, it's hard not to consider the Chinese a superior race.
@Keith
Great post. I love reading stuff like this. Thanks.
@Todd
My initial thoughts were along the same lines. While Keith mentions that the maximum cost of electricity (wholesale) to displace coal fired generation is ~$0.02/kw/h, I'd argue that this is only true in a BAU scenario. As time goes on, the price of coal extraction is only going to rise and this is largely a function of the thickness of the coal seam as well as the total amount of coal in place at a given deposit. Just like oil, we've already accessed most of the low hanging coal fruit.
While the recent price rise we've seen in oil appears large (e.g. from $60-90 in the last two years on a MA basis) it is small in comparison to percentage rises we've seen in the past. Between 1971 and 1979, oil prices increased nearly 500% in nominal terms. See this chart: http://en.wikipedia.org/wiki/File:Oil_Prices_1861_2007.svg
That's right about when northern 48 oil production peaked. What will happen to coal prices once China's production peaks? Granted coal isn't a "global" market like oil but still.... see Table 4 on this report:
http://www.fas.org/sgp/crs/misc/RL34746.pdf
If coal prices rise 3x in the next 10-20 years (not unrealistic IMO) then power prices are only 30% less than concentrated solar thermal power. If, in the same time frame, CST prices fall 6% per year, the generation cost will be ~$54/mw/h which would actually be significantly LESS than coal which would be ~$85/mw/h. If coal prices were to only double, the cost would be ~$74/mw/h.
In my opinion, it is very realistic to assume that concentrated solar thermal power will be competitive with coal in the coming years. CST is a very simple technology. The Egyptians used it to smelt metal thousands of years ago. Such a simple technology is exactly what our complex society needs if we are to continue enjoying something approximating the quality of life that we (westerners) now experience.
Since this is going to sound snarky, let me preface this by saying I'm not a Luddite. I like technology and had a PV system, solar hot water and energy efficient house over 25 years ago. I also got my first computer in 1988 - an XT clone. But, this is a brain dead idea concocted by bunch of fools.
There are many issues but I'm only going to pick one - resilience of the system. It assumes that everyone will sing Kumbaya and get along. If people are worried about a few nukes, how about taking out the world's energy supply or the ground stations. And, of course, no hackers would ever dare attack it.
It assumes that the technology will always be available in perpetuity along with the raw materials and manufacturing capabilities. Why perpetuity? Because once society starts down this road there will be no turning back. As Greer so often points out, we have already forgotten perfectly good "technology" from the 1970's.
So, all in all, I believe it is a brain dead idea.
Todd
"bunch of fools" no just one guy Peter Glaser. If technology goes down then this energy supply system will go down when it breaks or when it reaches end of life. There will be on the order of 1000 receiver antenna in the US. If someone blows up a few, say 10, then the grid will redistribute. As to hackers I suggest we do not network the critical control computers and we house them in a secure location with a second redundant backup site just like we do for banking and stock exchanges. Where are the NASDAQ computers housed? Where is the second set of 100% redundant NASDAQ computers housed?
I believe it is a brain dead idea.
I showed it was a brain dead idea in the old threat.
http://www.theoildrum.com/node/5306#comment-494573
PV is better than 1/2 the energy capture rate of the microwave idea.
PV is brain dead, also, at least as a way to keep this sorry civilisation going. At that scale it has no chance and may do more damage to our environment. If it's just to provide moderate amounts of power for a vastly powered down society then that's probably fine.
Great post. This is my favorite energy solution and has been since I heard about it in the 1970s.
You use 5Kg/KW and $300/Kg to GEO. I prefer Solaren's solution which is to push the wieght to power ratio. I do not know what value they are using but people can do 1Kg/KW and propose 0.25Kg/KW. This allows the use of SpaceX Falcon Heavy. We will see how they do.
The British have had this single stage to orbit space plane on paper for over 30 years. I do see that they are going to test some hardware this summer. Best of luck to them.
I've worked in "high-tech" for all of my life, designed and built research equipment that flew on the shuttle and I think this highly complex idea to put expensive, complicated things where they can't be repaired, and as Todd says, requires that even society functions for generations, is one of the most stupid things I've ever heard.
If you have 500-1000 people (or more) building them in GEO why can't you repair them?
I would go for tele-operated repair. Just as mining is done by tele-operation on Earth.
Well no, they are not. They are building them on the ground, then they launch them, totally unmanned, into the GEO. No one, to date, has ever went into the GEO orbit. Though they went through it, or near it, during the moon landings, but no man or woman has ever went into the Geostationary Orbit.
Ron P.
"They are building them on the ground, then they launch them, totally unmanned, into the GEO."
I really don't see how to do this.
At a few kg/kW, and dimensions in the kilometers, they are flimsy. Structural beams would be sent up as rolls of near foil thickness and run through roll formers.
"No one, to date, has ever went into the GEO orbit."
If you can think of any reason people could not live in GEO, please let me know.
That's not the point. The reason people never go into the geostationary orbit to repair satellites is that it is just so damn expensive to put people and their life support systems up that high for any length of time. It is much cheaper to just launch a new satellite when one peters out.
Ron P.
"is just so damn expensive to put people and their life support systems up that high for any length of time"
If you look at the cost of supporting people at GEO in the context of a substantial (100 GW/yr) power satellite building program, it doesn't cost very much at all.
The flow of materials is 60 tons per hour, 1440 tons per day.
Habitat, according to Bigelow, is 5 tons per person, 2500 tons for 500 people. That's less than two days of parts shipments.
Resupply of 10 kg/person/day would be 5 tons. 5/1440 is 0.35 percent.
Getting them back down is a pain, it's probably less expensive to ship up families and let them stay there for years.
100 GW/yr doesn't make any sense. Per year? Did you mean 100 GWH per year? Or just 100 GW? However 100 GW is over 17 times the size of the largest fossil fuel power plant on earth, 5,780 MW Taichung Power Plant in Taiwan. However it is only 5.5 times the power output of the Three Gorges Dam, the largest power plant in the entire world.
I flat just don't believe that. You had me going up until that point Keith.
Ron P.
"100 GW/yr doesn't make any sense. Per year?"
Yes. Over time this would increase to 1-2 TW of new power satellites per year. We need that much to get off fossil fuel in a decade or two.
"However 100 GW is over 17 times the size of the largest fossil fuel power plant on earth"
Not in one lump, twenty 5 GW power sats per year. One cranked out every two and a half weeks.
You need a hack of a big jig to hold them while they are being constructed, but one or two roll formers will make all the beams needed for this production rate.
100 GW in one power satellite might be possible, but I doubt anyone would want that much power in one location. Even 5 GW is uncomfortably large for utilities.
Incidentally, 5 kg/kW is 5000 tons per GW, 100 GW, 500,000 tons. 500,000 tons / 8000 hrs per year is where the ~60 t/hr shipping rate comes from.
Oh, pardon me. Now I understand. You are going to put 100 GW of power plants into space each year. You are going to put the equivalent of 5.5 three gorges dams, in power plants, in space each year. Or the equivalent of one hundred 1,000 MW nuclear power plants into space each year.
Well okay, if you say so. ;-)
Ron P.
"Or the equivalent of one hundred 1,000 MW nuclear power plants into space each year."
It should be obvious that it will take a good number of years to put the infrastructure in place and reach this rate. But that's simply the scale of the problem. I picked the 100 GW/year rate as the point in the build up where power sats would start making a serious contribution. That's in the context of human energy use of around 15,000 GW.
The alternatives as we run out of fossil fuels are not good. In spite of Fukushima, people will build more reactors if energy does not come from somewhere else. Japan, for example, has very few options.
If you object, do you have any suggestions that scale to the need?
I object due to the lack of detailed engineering analysis and the unrealistic assumptions being used.
Mass-to orbit rate of 60T/hour for starters.
Germany has stated that it is abandoning nuclear power.
I think Sweden has decided previously to do the same.
Terrestrial solar energy and wind energy is inherently more feasible due to the lack of necessity to use energy to reach Geo orbit.
Terrestrial solar PV/CSP, Wind, implementing much greater efficiency, and frankly, doing less with less energy.
Orbital solar power generation to provide for most of Earth's current and projected BAU power needs cannot be wished into existence because folks think that declining fossil fuels are 'not good'.
"Mass-to orbit rate of 60T/hour for starters"
Desired new power plants per year, 100 GW.
At 5 kg/kW, 500,000 tons, 8000 hours per year, 62.5 tons. (60 is close enough for this level of analysis).
Skylon in suborbital mode will lift 30 tons. With laser heated hydrogen (10 km/s exhaust velocity) about 20 tons of the 30 will reach GEO.
So to get 60 tons/hr takes three flights per hour.
"Terrestrial solar energy and wind energy is inherently more feasible due to the lack of necessity to use energy to reach Geo orbit."
The energy payback time for ground solar is 2-4 years. The payback time for power sats with the parts lifted by a combination of Skylon and laser propulsion is under two months. That is fully analyzed in the article.
The rest of your objections are not really more in the way of opinion "doing less with less energy."
With respect to Germany, Sweden, and all who join them, the problem is the pattern we've seen so far:
1. country builds nukes.
2. something goes bad somewhere; nothing is ever perfect.
3. country goes ape, swears off nukes, sets shutdown deadline.
4. deadline approaches, almost time to turn out the lights.
5. population can't live in the 19th century any more, so deadline extended.
6. repeat starting mainly at (2)
Most of this stuff is very time- and capital-intensive. So it's not possible to flipflop on every glandular whim, alternately scared witless by the threat of rejoining the 19th century, or else by the threat that nothing in this world ever carries absolutely zero risk. The upshot seems to be that "we" have lots more early nukes than we ought to, since we can't ever commit long enough to get new ones built before some glandular reaction upsets the applecart yet again. OTOH the ground-based wind and solar can't be wished into existence either; nor can the possibility of months-long windless or cloudy periods be wished away; nor can the finiteness of Scandinavian hydro capacity be wished away; nor, when it comes down to it, is Europe genuinely going to be willing to have its all tethered to a trans-Mediterranean cable that can be cut in an instant. I really don't see a clear answer here, except that eventually when we look back in the rear-view mirror, we'll see that a lot of coal and methane were burned.
Were I an investor then I'd pass the nuke option if my capital return depends on step 6... Way to risky that some politician would stand straight one day.
2. something goes bad somewhere; nothing is ever perfect.
And given the horrible consequences of the eventual failure - its no wonder the idea that has failed to live up to what was promised should be curbed.
Solar PV and Wind can still give Mankind a life far better than the Kings of old Europe ever had.
Terrestrial solar energy and wind energy is inherently more feasible due to the lack of necessity to use energy to reach Geo orbit.
Exactly.
Now if the 'capture space energy and return the product back to Earth' model wants to be chased after by dreamers - robots to mine and process ore into refined metals is a fine goal.
And rather than making posts to internet forums the dreamers can grab a keyboard and start working on vision systems and AI's to make it happen.
They can just ride the elevator to the job.
Space Elevator Competition Extended One Day: 22 October 2006 Time: 11:28 AM ET
http://www.space.com/3030-space-elevator-competition-extended-day.html
==
Term of the day: techno-cornucopian triumphalism
Definition: The quasi-religious belief that someday someone somewhere will come along and solve one or more nasty problems facing society, and make nice profits for the oligarchs too.
… for example, that ‘new technology’ will magically emerge to solve the Peak Oil problem.
http://ijimlp.wordpress.com/2009/10/03/term-of-the-day-techno-cornucopia...
If Solaren is successful then we call it entrepreneurial. If Solaren fails we call it techno-cornucopian triumphalism. I am willing to wait until 2017 to see.
"The quasi-religious belief that someday someone somewhere will come along and solve one or more nasty problems facing society, and make nice profits for the oligarchs too."
Without so specifically referencing the source of the salvation, that is how it works.
In the late 1400's, things were looking bleak. The aristocracy were down to trading silver sword-hilts, etc., because of the "money famine". Then the New World was discovered. Out of the blue... the stuff of mystic visions... came and saved the day. Indeed, the rich got even richer as the festival of exploitation surpassed its old vigor.
If it hadn't happened, the alternative future Europeans may have been rousted from their huts by superiorly resourced, armed, and regimented Native American imperialists..
Solaren claims to be building something by 2016. Never mind for the moment whether that's vaporware. Surely they're not planning to put people in GEO by 2016, since no one has the necessary kit. Surely their apparatus is planned to be assembled automatically?
Solaren's web site looks rather dead to me. There's just the front page to watch, with a note to contact them thru e-mail and nothing more...
E. Swanson
Looks like Gary T. Spirnak is still operating Solaren out of his home office.
Address: 32 Monterey Court, Manhattan Beach, CA 90260
Or, have they moved out into a real office like a real company???
E. Swanson
Yeah, but I still can't imagine that anybody in their right mind, or even anybody under a lot of illusions such as Solaren may be, would ever consider having human crews build this stuff at GEO anytime in the next few decades, never mind by 2016. Solar-satellite construction seems just what robots or automatically deploying assemblies are for, so I didn't really understand the original "I don't see how to do this."
N.B. I'm not confident the USA will even have manned access to LEO any more, or at least not for a good long time, since at the very minimum, someone would have to select some methodology and commit to it long enough to get it built and working. Same problem as with the so-called high-speed trains - no sufficiently firm and long-term commitment even with respect to populated corridors where they might actually work.
US manned access to space see http://www.spacex.com/dragon.php This capsule has already been launched, orbited, and returned safely to Earth. Future launch dates are on the SpaceX web site. The emergency escape rockets required by NASA are in development paid for by NASA. The rockets will be built into the capsule. They can be used for four things:
1) escape during launch
2) soft touchdown on land after re-entry into Earth atmosphere
3) orbital insertion Mars
4) soft touchdown on land after entry into Mars atmosphere (not sure if they are enough to do a lunar landing)
"If you can think of any reason people could not live in GEO, please let me know."
Expense. Robots are cheaper they do not need air or water.
If that's your only argument, then go back and look at how much they cost in the context of 100 GW, worth $160 B, per year.
Air, water, food and the rest is only about 0.34 percent of the cargo flow to GEO.
The Microwave link is what concerns me the most with this power generation scheme. Moisture (clouds and rain) could substantially reduce the efficiency and you might get some cooked birds falling out of the sky now and then...
As I recall, a big thunderstorm right over a rectenna will absorb as much as several percent of the power.
The power level isn't high enough to cook birds.
The more serious problem will probably be millions of birds roosting on the rectennas in the wintertime to keep warm.
Ha! I could see it now, the human race celebrates a significant achievement: space based solar power. The complexity of the task was huge and the technology necessary to make it work was simply awe inspiring... only to have the whole thing foiled by birds.
yeah - I didn't realize the power was that spread out. What frequency are they considering for the power transfer?
"What frequency are they considering for the power transfer?"
2.45 GHz
Haha! I wish there were a way to mark posts as funny :-D
I can see it now -- 802.11m -- power over wifi!
Wait, you're not serious are you? Uh oh...
An ISM band:
http://en.wikipedia.org/wiki/ISM_band
Percy Spencer... was working on an active radar set when he noticed that a peanut chocolate bar he had IN HIS POCKET started to melt. The radar had melted his chocolate bar with microwaves. The first food to be deliberately cooked with Spencer's microwave was popcorn, and the second was an egg..." ON AN OPEN TABLE! The old radar guys used to wave their heads around to see where it got the hottest to find and define the beam.
"Microwave heating is more efficient on liquid water (than on frozen water, where the molecules are not free to rotate) and on fats and sugars (which have a smaller molecular dipole moment). Microwave heating is sometimes explained as a resonance of water molecules, but this is incorrect: such resonance only occurs in water vapor at much higher frequencies, at about 20 GHz. Moreover, large industrial/commercial microwave ovens operating at the common large industrial-oven microwave heating frequency of 915 MHz—wavelength 328 millimeters (12.9 in)—also heat water and food perfectly well."
http://en.wikipedia.org/wiki/Microwave_oven
http://en.wikipedia.org/wiki/Polar_molecules
http://en.wikipedia.org/wiki/Molecular_dipole_moment#Molecular_dipoles
Microwave ovens use 2.45 GHz. We've been "cooking over WiFi" since before there was WiFi.
Are you sure that's the right one? I thought 2.45G was selected for microwave ovens because it was efficiently absorbed by water (and birds) rather than passing through.
There are plenty of ISM bands.
The geosynchronous orbit is 35785 Km., or about 22236 miles above the equator. And it must be directly above the equator. The area of solar collectors in space would have to be huge. I could not find in your post just how large an area they would have to be, nor the area of the antenna farm on the ground. So I googled it and found this at: Space-Based Solar Power Satellites
Okay you propose to use lasers instead of that 1 square kilometer transmitting antenna. But you simply cannot get around the many square miles of collection area. This would act like a huge parachute catching the solar wind. It would take thrust engines working constantly to keep the system in the geosynchronous orbit. And every solar storm would blow it miles off course. The thrust engines would have to fire up even harder to push it back to it's proper place.
In space all thrusters require mass. To move in space you must throw something else in the opposite direction. Spent rocket fuel is what is used as thrust mass, be that hydrogen or whatever.
The system would require constant maintenance. It would not be like repairing the space telescope, this thing would be many times further out and the electronics would be a nightmare. Plus the thrusters would require fuel, real rocket fuel. Just refueling would be extremely expensive and dangerous. Like I said, a real nightmare.
I think the whole idea is an armchair pipe dream for people who just love dreaming up such things. You know, Star Wars and Trekkie fans who just love thinking about such things.
I agree with Augjohnson above who says it is one of the stupidest things he has ever heard of.
Ron P.
Good point on the solar wind moving the whole system. GeoSync orbit doesn't have much protection from solar wind/storms since it is so far out.
Just imagine this! Slightly worse than interrupting your TV viewing!
Rogue satellite may impact cable TV in U.S.
The kw/m2 for a solar panel was pretty low back in 1973. I would recommend looking at http://www.nss.org/settlement/ssp/library/nsso.htm for more up to date analysis. You would still need a large transmitting antennae because the physics of microwave transmission are inflexible. A 1 km transmission antennae means about a 10 km collection area on the ground. This would be a forest of rectennas on the ground. The microwave energy will be very dilute by the time it reaches the outer atmosphere not to mention ground level. Someone walking through the collection area on a sunny day would get more ultraviolet radiation from the sun than microwave radiation from the satellite.
When it is noon the solar wind blows the satellite towards the Earth. When it is midnight the solar wind blows the satellite away from the Earth. The net effect over a 24 period is zero.
No that is simply not correct. This would be true only two days a year, at the spring and fall equinox. All other days of the year the sun would always be at an angle to the Geostationary Orbit. The angle would be very steep at the summer and winter solstice. The Geostationary Orbit is directly above the equator you know.
All that being said, even at the spring and fall equinox the force of the solar wind is always much stronger on the solar side of the earth. (See example below.)
The Van Allen Belts are swept deep into space on the opposite side of the earth shielding the solar wind. The net effect would be a much stronger push toward the earth than away from the earth. During the daylight hours on earth the satellite would be deep into the "bow shock" section of the solar wind.
And you still have those violent solar storms. They play havoc with ordinary satellites, imagine the effect they would have when the wind from such a storm hit a solar sail many square miles in area.
With very small satellites the area exposed to the solar wind is not great enough to knock them out of orbit. But with a sail several square miles in area there would be little hope of keeping them in orbit.
Ron P.
The lasers are to get parts up, not energy down.
The solar wind is a minor force. The bigger one is light pressure of 9 N per square km. On really light power sats that disturbs the orbit. On relatively heavy ones it averages out to zero over a year.
Keeping the transmitting antenna pointed the right direction is a big problem, but what seems to be the best way to keep it pointed in the right direction is gravity gradient. A one ton mass and 600 km of string will give a 1 newton force and 500 Nm of torque connected with a bridal to the transmitting antenna.
It still takes some station keeping reaction mass, but that's on the order of a few hundred kg/year using electric thrusters. In the context of a 25,000 ton power sat, a few tons would keep it in place for a century.
Another issue I saw discussed a while back is that there is growing competion for GEO space: it's getting crowded out there.
Will using up large portions of the Geo slot require "property rights', space leases or easements? Just askin'. And what about the microwave beam's effect on lower, non-syncronus satellites who's orbits may intersect the beams? Again, just askin'.
There's no worries regarding useful Geosynchronous slots. At now, the Clark orbit slots are spaced about 100 km apart on a single circular track. I've proposed the Gould orbits, which are slightly eliptical orbits which put the satellites on an eliptical track which goes 100 km above the Clark track at one side of earth, 100 km below at the other and 100 km North or South when altitudes are the same. These orbits are particularly useful for solar energy satellites since those need their arrays to constantly track the sun anyway, so also tracking 1 or 200 km offests to their earth stations is no biggie. There are 3 to 5 times as many slots in the first order (+-100 km Gould orbits) as in the Clark orbit. If necessary, you can then go to 2nd or 3rd order Gould orbits (eg. +-200 km, +- 300 km elipses).
From the POV of an observer in the Clark orbit, a satellite in the Gould orbit in one of the 3 (or more) corresponding slots will appear to "orbit" around the observer at 100 km distance, moving very slightly ahead when below, slightly behind when above.
I've put the concept into public domain so no company etc. can patent it and exploit it for profit.
With so much working going on in Geo, removing dead satellites would be simple and sensible. One might well replace stand-alone comsats with platforms on the powersats; the boost from a few thousand watts to potentially megawatts and kilometer-size phased arrays make worldwide communications a snap.
And every solar storm would blow it miles off course.
But a CME will have no effect PER the poster.
http://www.theoildrum.com/node/7898#comment-809229
Since Eric insists on chasing this ghost around the page: in a word, no. Even a full-blown coronal mass ejection would only push it less than a millimeter per year from where it would have gone otherwise. By the time they reach earth, these storms and ejections consist of ultra-high vacuum; they pose electrical and ionizing-radiation issues.
So this thing has enough problems, some of which you listed, but being blown abruptly and hopelessly off course as if it were an 18th century barque caught in a hurricane is certainly not among them. As with any other synchronous satellite, it would need thrusters to provide the occasional squirt to keep it on station, offsetting the small long term cumulative effect of solar wind - and also light pressure. Coping with the tiny added deviation from a solar storm or CME would be much, much less than child's play.
Excuse my skepticism but I'm from Missouri -- you'll have to show me.
None of the pieces of this proposal exist yet and it is clear that funding any of those pieces will require massive subsidies, removing money from the otherwise 'productive' economy. Because of the engineering intensity involved it seems like there are many single-points-of-failure. For instance, how would satellites be hardened against a large solar storm? It's also hard to believe that such a system could possibly scale to the Terawatts of power that are needed.
And what happens when one of those microwave beams accidentally goes off target. (Not to mention potential malicious uses.) The one thing we've learned over the past year is that accidents happen even with the largest, most expensive, most technologically advanced energy projects.
Let's examine the proposal of one of the few companies out there promoting this. A quick look at Powersat's Basline Physical Performance Model shows that they are planning to beam energy down to a receiving station at 450 Watts/m^2. Heck, the average insolation for the entire earth (ignoring clouds) is 240 Watts/m^2. In the Mojave desert, with 340 days of sunshine, insolation is 310 W/m^2. All that complexity only gets us a 45% increase over insolation in goood desert areas?!!
Given that we have to build receiving stations (ie. solar panels) either way let's skip the centralized, massively complex, hyper expensive satellites and just help people install solar panels on their homes.
Space based solar is pie-in-the-sky.
Jon
Solaren is doing it today with zero sudsidies. They are on schedule to deliver 200MW to PG&E in Fresno California from Space.
"on schedule"
ROFL.
Call us when it's been delivered.
Close. Space based solar is fantastic for space based applications.
Beamed power is still not looking promising.
Concerns about microwave beams going "off-target" and damaging anything are unnecessary. The energy density would be lower than sunlight, and the only potential damaging effect is thermal heating (eg. sunlight is far more dangerous), so obviously not an issue.
You're missing the fact that space-based solar collectors are illuminated by 1.3 times as much energy for something like 3 to 4 times the time per day. Reliable, continuous energy. And microwave recievers / converters are extremely cheap to build with low-tech materials at very high efficiencies, unlike solar PV.
In orbit 1350W/sqm versus your 310W/sqm that is more like a factor of 4 or 400%. That is worth some effort. But the big win is it is baseload 365/7/24 in orbit.
"funding any of those pieces will require massive subsidies, removing money from the otherwise 'productive' economy"
We don't produce anything. We kill other people's children for oil* so we can drive to work in Japanese cars and sell each-other Chinese goods and then drive home to sit in front of our Korean video monitors and escape into utter unreality. The prison system is the biggest money-moving entity in California... The prison guards have the most powerful union and lobby. There is "structural unemployment" because workers aren't needed, only clerks and soldiers. It is a slave-holding economy whose agribusiness depends on a massive influx of people without rights. Oh, and we gamble: stocks, mortgages, commodities, etc. We are the biggest debtor nation on earth.
It does not matter what a civilization makes... pyramids, space programs, or empty cities like the Chinese are building. There has to be flow.
"All that complexity only gets us a 45% increase over insolation in good desert areas"
No one lives there. Power transmission lines have to be built over long distances. A lot of power is lost in these systems. Too, the added power is available 24 hours a day.
"Given that we have to build receiving stations (ie. solar panels)"
The receivers are simple, passive metal structures.
Use facts.
______________
*resources, and labor...
Vietnam was over France's plantations and slave labor for Michelin tires and latex rubber.
http://www.buzzle.com/articles/foam-mattress-history-and-buyers-guide.html
The shopkeeper's view and pitch!
Its a nice dream and thought experiment.
I suggest developing terrestial power sources further including solar power and continue advancing space technology and practicing building large structures with a science return such as optical and radio telescopes.
It is probably harder to get this working then fusion power but we can do somethink practical while dreaming and while we have have lots of energy use a small part of it to gather knowledge.
Thanks, Keith, for putting together this interesting update on space solar. As you point out, there are still a lot of obstacles.
I know on "regular" renewable energy projects, there is often a four stage scale up - a laboratory project; a pilot project; a small scale commercial project; and finally a large scale commercial project. It usually takes this many steps to get all of the "bugs" worked out of the system, and to get costs down to a reasonable level. A smaller scale project might also show whether microwaves would cause huge problems. It seems like the this kind of project would be difficult to do in incremental steps of this sort, and that would be a difficulty.
Any thoughts?
It's hard to do in small steps.
The big problem is getting the cost to GEO down to where power sats make economic sense.
Trying to build just one with current or projected regular rockets is more expensive than building the transport system and building dozens of them.
On the other hand, the Japanese have to do *something*.
In order to compute a reasonable launch cost estimate, one must know much more about the proposed system. Your initial post tells us nothing about the mass of the satellite vs the power produced. Solaren and others have proposed systems using concentrators, with mirrors made of inflatable material, which would tend to reduce the mass, but Solaren appears to be dead. The proposal for the Skylon vehicle is totally guess work, as they haven't launched anything as yet and their engine concept is untested. Your assumption of many launches per day and (presumably) quick turnarounds is thus total illusion.
Your comments about the transmission of energy from GEO to the surface ignores the fact that communication satellites don't transmit to small footprints on the ground. So far, the only test data has been an experiment over 92 miles between mountains in Hawaii, which is said to have resulted in a 92% efficiency. But, from GEO to ground is almost 200 times further and the beam is going to spread along the way. It's likely that there will be tracking problems, since the collecting surface must point toward the sun at all times and the transmission antenna must point toward Earth, thus requiring some rotating link between the two, with the problem of bearing failure.
This latest post is so full of "If" and "Maybe" that it would make better science fiction than a serious proposal to build something. Please get real, we don't have enough time to waste building a bad system while betting the farm on it's success...
E. Swanson
"Your initial post tells us nothing about the mass of the satellite vs the power produced."
I don't know how, but you seem to have missed it. 5kg/kW.
"The proposal for the Skylon vehicle is totally guess work, as they haven't launched anything as yet and their engine concept is untested. "
ESA report commissioned by UK Space Agency finds “no impediments” to further development of Reaction Engines’ SKYLON Spaceplane
The report states that:
Success on future engine test would mean "a major breakthrough in propulsion worldwide"
No critical topics have been identified that would prevent a successful development of the engine.
http://www.reactionengines.co.uk/downloads/Confidence_in_SKYLON_24.05.20...
"likely that there will be tracking problems, since the collecting surface must point toward the sun at all times and the transmission antenna must point toward Earth"
These problems and multiple solutions have been understood almost from the day of the invention some 40 years ago.
"Success on future engine test would mean 'a major breakthrough in propulsion worldwide'"
I'm still seeing a conditional tense here. IOW it hasn't been tried yet. Something tells me this is for, at a WAG, mid-century, if it comes to be at all. That's hardly a reason not to try it, but OTOH I'm not setting much store by it. (And this is all hilarious because usually I'm wondering if the doomers are properly considering what they wish for, rather than wondering whether an engineering scheme is too pie-in-the-sky to matter much anytime soon.)
Oh? Are you sure that you can connect the multi megawatt output of a fixed PV array to a moving antenna across a rotating coupling? How about cooling the PV arrays in a concentrator design? Have you calculated the mass of the cooling system for the complete satellite? When you've done the preliminary design and calculated all the numbers, get back with us, until then, you are dreaming of smoking some funny stuff...
E. Swanson
Multi _GW_. Given a 50% loss, a 5 GW output on the ground has to transfer 10 GW into the transmitter. And yes, it's been figured out, Boeing figured out several ways back tin the 70s. One of them was mercury slip rings, another was inductive. If we use high speed generators, inductive would work fine. The other alternative would be to use a variation of the way Solarn proposed and send light through the rotating joint with the power plant aligned with the transmitter.
I don't favor PV. Thermal is more efficient and there is a large industry making turbines already. Heat pipes would probably be the way to go if you did use PV.
It's around a kg/kW. Turns out that there is a diseconomy of scale. Radiator mass per kW of radiated heat in very large radiators goes up as the square root of the absolute size. So a radiator 100 times as big has ten times the mass per kW of the smaller one.
My you are a polite person.
So, all your hand waving about PV is just for show? You really want to orbit Rankine Cycle hardware, like the turbines in a 1,000 MWe nuke? Remember that those operate at high pressures to achieve the efficiency, so a single leak would be catastrophic. Maybe you intend to use another working fluid, such as propane or ammonia. Who knows, since you just threw this on into the mix. Let's see your CAD drawings. Show me the blueprints...
E. Swanson
Other than a mention in passing, please show me where I have been "hand waving" about PV? The article is about getting the cost to GEO down and not on the details converting sunlight into electric power on satellites. Maybe you mixed me up with Darel Preble who is a PV fan.
Rankine, Brayton, supercritical CO2, whatever works best. Possibly in 50 MW units so they can be shipped up on one piece, probably cascaded to get the efficiency up and the amount of heat radiated down.
Can you read CAD drawings? (I.e., do you have the software?)
Your system cost comparisons were based on PV costs on the ground. Looking back at the top article, I don't see any cost estimates, other than launch cost per kg and the mass of the system per kw. Lots of hand waving, just not totally based on PV at GEO.
When I was working on a project for the ISS design, I used DesignCAD running in DOS, which was a low cost alternative to AutoCAD. Later versions of that program would convert several common file formats for viewing. I purchased a more recent version of DesignCAD for Windows, but have not activated it...
E. Swanson
Can you read CAD drawings? (I.e., do you have the software?)
Tell ya what - post the URL where it can be DLed and I will make sure they get translated into a format Black dog can use.
That should be able to be done in the next few days before this thread locks because they should have already been done.
Remember that those operate at high pressures to achieve the efficiency, so a single leak would be catastrophic.
Given the leak would introduce a force on the space boondoggle - the direction it would head would be uncontrolled.
Esp. if the leak came from a collision from a small micrometeorite.
http://curious.astro.cornell.edu/question.php?number=470
That's a whole lotta small bits wizzing about there E. And what sized thing at what speed hitting the proposed boondoggle will cause the leak?
No rotating coupling it is a phased array, gravity gradient stabilized, that points down.
At least, Keith_Henson understands what I was referring to. You missed the point entirely...
E. Swanson
You might want to explain what you're talking about for the benefit of other readers, rather than looking down your nose at the commentator and being cryptic.
Am I correct in reading your comment to mean that you were talking about the coupling between the collector/generator assembly, which tracks the sun, and a separate transmitter assembly (or individual members of a phased array of transmitters), which tracks the Earth's antenna site?
I note that a phased array of transmitters doesn't need to move with respect to the target, as long as it presents an adequate cross-section to the beam direction to form the beam. And it can be a three-dimensional structure so it can present an adequate cross-section in any direction. If you want to build it tight to the collector and not have the beam occluded when the target is sunward of the array you can put some of the transmitters on supports some distance sunward of the array, positioned so the shadows fall between panels (though this costs you extra transmitters).
However, as Keith points out, getting gigawatts of electric power is a solved problem, so why bother?
Getting microwaves through a rotating coupling is also a solved problem. Radar antennas use it all the time, with continuous rotation through a full cricle: Circularly polarized waveguide along the axis of rotation, split so the ends rotate freely with respect to each other, with a non-contact choke joint at the split to keep the microwaves from leaking out there. Not appreciably more lossy than any other section of waveguide. If you want a rough aiming antenna on each transmitter of your array that's one way to do it.
The only trouble I see with mechanical contraptions, even when they are "solved problems", is that they have a nasty way of requiring constant maintenance and replacement. Wearout is not desirable in high orbit; for that matter it's not even desirable in high ceilings down here on earth, as per a discussion on lighting in yesterday's DB. Also, bearings and the like don't always work the same in high vacuum as they do down here in the atmosphere.
The collector portion of the system must point toward the sun. That implies that the collectors must rotate once a year in the Sun centered inertial reference frame about an axis which is perpendicular to the ecliptic plane. At the same time, the transmitting antenna must also rotate once a day in an Earth centered reference frame, in order to face the rectenna on the earth. These rotational axes are not parallel and thus there must be some sort of rotational coupling between the two segments of the satellite.
The necessary cooling of the various parts of the system add further complexity. PV cells in a 1x configuration can be passively cooled and some distributed PV systems using concentrators also may be passively cooled. A higher concentration system, be it PV or thermal, requires plumbing to remove the thermal energy and the radiators must be oriented pointing away from the Sun, which would likely result in their being attached to the first segment.
If the power conversion electronics were located on the second segment, the cooling system must also be mounted via some rotating coupling, else the radiators would periodically face the Sun, with negative consequences. If the power electronics were located on the first segment for cooling, the joint with the transmission antenna would need to carry microwaves, which might preclude the use of a phased array antenna. I'm not an electronics person, but I understand that the proposed satellites include phased array antennas.
The functional success (and the cost) of the power satellite rests on the design solution(s) for the thermal control system, as well as the design of the solar collection portion. That's why I wanted to see something more than words from the author of this piece...
EDIT: Another way to visualize the SBSP system is to think in terms of an Earth fixed coordinate system. Given that the satellite is in a GEO location, the resulting motion would appear as if the first segment which collects the sunlight is rotating around the second segment (with the antenna) at a rate of one revolution per day. The second segment appears stationary relative to the surface of the Earth below. But, that appearance misses out on the fact that there are actually two rotations in progress, since the yearly motion is less than 1 degree per day. Given that there are two axes of rotation, it would appear that a third segment (or other adjustments) would be required to connect the other two segments mentioned above. The same sort of problem arises in Earth based solar collection systems using concentrators, which have resulted in the use of 2 axis gimbaled tracking devices. Higher concentration (a requirement for high efficiency) requires more precise solar tracking accuracy as well...
E. Swanson
The difficulty of designing power satellites pales in comparison to the lift cost problem. Even if you go the lunar or asteroid mining route, lift cost is still a huge problem and will be until something like nanotechnology can put a seed industrial base in the size of a coke can.
Even so, I have thought about it.
Space is really flat out at GEO. Still a one ton mass and 600 km of kite string will produce a 1 newton radial force on the string. You attach the string to a bridle 20 km or so out from the transmitting antenna and from there to the edges of the transmitter disk. (The "kite string" would actually be one of those redundant ladder tethers to resist micrometeorites.)
With slight adjustment of the lengths of the bridle strings you can point the transmitter to a spot on earth as needed. The transmitter disk is now fixed in orientation and resistant to being pulled out of alignment up to where a bridle string goes slack. Around the N/S axis, it can generate a respectable 500 Nm of torque. All you need to keep the solar collectors pointed at the sun is a clock drive motor with enough torque to overcome the bearing friction.
The whole power satellite can still rotate around the axis established by the string. The earth's magnetic field is weak out that far, but a small current flowing in a big loop of wire might be enough to keep the satellite oriented (I have not run the numbers). If not, there are low mass consumption thrusters and light sail effects to keep the N/S axis aligned.
One can ignore the yearly rotation and control the collectors using the rotation about the N/S axis parallel to the Earth's rotational axis. That works for PV, although there's a penalty in that the output varies with the cosine in the angle between the two axes (which is 23.5 degrees) and thus there can be a fluctuation of up to +/-0.91 as the satellite orbits. However, if your system is to be a thermal concentrator system, the second axis can not be ignored. That's the result of the high concentration required for efficient operation of the collector. (I went thru the design process for a concentrator system about 35 years ago.) In either situation, your design will still require a rotating joint of some size to transfer the energy from the collectors to the segment with the antenna.
As for gravity gradient, I think there's the possibility of undamped oscillations due to the pendulum effect. There's likely to be unbalanced forces due to solar pressure on the combination of the collectors and the antenna. Some proposed designs are symmetrical, but we don't know whats in your head or system model. Given that the antenna is probably a phased array system, I understand that some correction for tracking errors is possible, but that's beyond my experience...
E. Swanson
No, you also need a system to counter induced torque which will end up at some sort of thrusters. Even reaction wheels need to be de-spun from time to time.
NAOM
"Gravity-gradient stabilization is a method of stabilizing artificial satellites or space tethers in a fixed orientation using only the orbited body's mass distribution and the Earth's gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction wheels is the low use of power and resources."
http://en.wikipedia.org/wiki/Gravity-gradient_stabilization
Perhaps I don't understand this. As I understand it, the sunlight collecting part of the power sat is spinning in inertial space once a year. The transmitter is spinning in inertial space once a day to keep pointed at the earth. If they were not connected with a bearing, they would go on doing this more or less forever.
If there is a motor on the bearing that just overcomes friction, where do you get induced torque?
Sorry, no intent. The article was about lowering the cost of parts to GEO, not about power satellite design. Presumed people can get basics from Google/Wikipedia.
Yes.
I have a vague memory that someone showed this would have problems. Something like it took both careful phasing and a flat surface to reach the beam quality needed.
I don't think that has been proposed for a power satellite before. At least I don't remember it. Might be an idea to look into. Might be a problem at this power level.
Commenting on: phased array of transmitters
Perhaps this was the comment which you recall:
http://anz.theoildrum.com/node/5314#comment-494960
Roger Arnold wrote that one and has also offered similar comments in this discussion as well...
E. Swanson
It doesn't require a flat surface. Curved surfaces work just fine. But to avoid lots of sidelobes, you need a relatively continuous surface. A spherical SPS skinned with PV panels incorporating slot antennae on the earth-facing side and driven in the proper phase relationship would be able to generate both power and tight, accurately-pointed output beams.
But just how lossy the rotating joint? If the loss is only 0.01% of 10 MW you are still talking of 1 kW into the joint. Anything near 1dB would be very bad news.
NAOM
Newsflash: The vast majority of our future energy will necessarily come from contemporary solar captured by leafy plants.
As such, we should be investing in the 'technology' used to harvest this energy -- healthy soil & perennial vegetation.
All else is empty techno-masturbation at this point.
See http://www.energybulletin.net/stories/2011-05-31/perennial-imperative-br...
Plant photosynthesis is extremely inefficient. We can build solar energy receivers now which are orders of magnitude more efficient than photosynthesis and thus use far less land area; require no irrigation, fertilization or tilling and harvesting machinery or fuel; last for multiple decades; don't exhaust the cropland we need for growing food; provide their output energy in high-quality electricity rather than nearly usless wet biomass requiring extensive further processing.
When 1 hectare of (poor soil quality) earth-bound solar-electricity generation can provide exactly the same net output as 300 hectares of intensive energy crops on top-quality farmland, why are we even discussing this? Oh, I know, someone's got a buck in it.
Hey, I'm with you on solar, but don't you see that these "solar energy receivers" just won't be built on any scale that matters?
We've had 40 years to build them & we haven't. And we won't.
They require a cheap-fossil-energy infrastructure (physical & socio-economic) that just won't exist much longer. Broken & non-existent solar receivers are 0% efficient.
But the infrastructure of soil & perennial vegetation WILL still exist & we WILL use them again as our primary energy source. No choices here.
It's time to accept the biophysical rules of the industrial endgame & adjust accordingly.
I think Dan meant that we will use plants again "as our primary energy source", not in the biofuels for SUVs sense, but in the old fashioned mostly-food sense. In other words, we'll have and use a lot less energy in total. Because when we had the chance to use our one-time endowment of fossil fuels to build a sustainable energy infrastructure, we used it instead to go "weeee" in our SUVs. Now it is too late to change that trajectory significantly.
I also think that the fixation with "efficiency" is misguided, perhaps a symptom of our "growth" religion. At this point, when the vast majority of roofs have no solar panels on them, why do we need to worry about whether, for a given wattage, we need to cover, e.g., 2% of the roofs (at low "efficiency") vs. 1% (at high "efficiency")? The watts per dollar are a lot more important than the watts per square meter. And in that department, those biological solar panels that reproduce themselves are surely the best.
Regarding major projects that require a massive re-focusing of national priorities, note that there are much simpler and cheaper things that we could have done (and still can do), that would give us huge yields in "negawatts", but we spend the money (i.e. remaining fossil fuels) on military toys instead. And some subsidies for net-energy-losers such as corn ethanol. As has been said here before, Peak Oil is not a technical problem, it is a social problem.
Concerns about efficiency arrive because some people are talking about covering 10% of the roofs with solar collectors, while you are talking about covering 10000% of the roofs with solar collectors. At that levels of efficiency, area and harvesting start to be quite important.
Installation cost is 3 $/sq m on a residential roof. That is regardless if it is 10% eff. or 20% eff. But of course what we care about is the cost to install per watt $/W. So higher eff. is lower installation cost. By a factor of two in this example.
50 years ago, PV cost hundreds of dollars a watt for cells and the best was 6-8% efficient.
http://en.wikipedia.org/wiki/Solar_cell#Bell_produces_the_first_practica...
Now modules are pushing a buck a watt and efficiencies range from 6% (cheap a-Si) to ~10% (Cd-Te and CIGS thin-film) to ~15% normal crystalline silicon to 20+% high efficiency silicon to 35% (multi-junction). Can you say "learning curve"?
Oh, and last year there was "only" 17.5 GigaWatts of PV installed worldwide.
http://www.renewableenergyfocus.com/view/15219/solar-pv-installations-re...
That's total installed capacity of something like 37.5 GW.
Using a conservative 5 hours a day of full sun, that's 188 GWh of electricity a day,
68 TWh/year.
188 GWh/day is 7.8 1 GW coal and/or nuclear plants running 24x7.
"no scale that matters" ???
Last year 2% of all German electricity came from PV (and they have less-than-good insolation).
http://en.wikipedia.org/wiki/Solar_power_in_Germany
Just ten years ago, it was essentially zero.
This Solar Energy Industries Association PDF has 27 GW of utility scale solar operating/under construction/in development in the U.S.
http://www.seia.org/galleries/pdf/Major%20Solar%20Projects.pdf
n.b. did you catch the growth rate? 17.5 GW installed in 2010, adding to a base of 20 GW.
The implication is that PV manufacturers basically doubled their capacity last year.
Could they do it again? Well, they've done it before... The issue is the market size.
With a 1 to 3 year (and falling) energy payback, and 20-25+ year life, PV can breed if/when it comes to that.
I'm NOT saying BAU can proceed on PV, but PV is capable of providing a lot of electricity and is ramping rapidly right now.
Wood from a wood lot captures 0.1% of the sun light energy.
Corn captures 1% of the sun light energy.
PV captures 18% (cheap) to 40% (expensive) of the sun light energy.
I will go with the 18%. You can work on the 1%.
Well Mr. 18%, that all depends on if you're gonna be able to GET functioning PV's in 10 years.
I'm not confident in that assumption.
"...So do ya feel lucky? Well do ya, punk?" :-)
I think the 1% is the safer bet.
predicting is hard especially about the future ;)
I do not know. I will just wait and see.
PV will come down. People will install it. Bill Gates actually said people would not buy computers and we are all using laptops.
I feel more confident that factories will build x amount of PV or solar thermal systems once every 25 years in future than I do that someone will come up with a magical fairy-dust method of supplying you with sufficient phosphate fertilizer and agricultural machinery to re-plant 300x area of crops. And you should reduce your claims of plant photosynthesis preformance to account for fuel and nitrogen fertilizer used in your costly machinery. Or are you talking horses, oxen and more taxpayer-supported magic?
Wood from a wood lot captures 0.1% of the sun light energy.
Corn captures 1% of the sun light energy.
Got a reference for that?
I think you will find that both crops can harvest significantly more than 0.1 or 1%.
Not the 18% of panels, to be sure, but you are lowballing the biomass numbers.
We can back-of-the-envelope the corn. For corn, Wiki says 3000 liters/hectare, and even in Iowa they crop once per season. (Note that Brazilian ethanol is only 7500 liters/hectare, so given all that tropical sun it's hardly a magic elixir.) Iowa State says 23MJ/liter. So that's about 71GJ.
That hectare receives nearly 10MW in full summer noon sunlight, and likely averages somewhere around 1.25 to 1.5 MW year-round 24/7. IOW it receives around 39000 to 47000GJ per year. So at best we convert 71/39000 of that sunlight to ethanol, or 0.18%. Now, there's more energy in the cellulose, and some of that could be useful burned in stoves locally. OTOH we can't take it all away and expect to keep growing crops indefinitely.
So from the back of this envelope I don't see how we quite get to 1% in practical terms, and what we do get is only chemical energy, around three-fifths of which will unavoidably be shed as heat on the way to doing useful work, unlike electricity from solar panels. It seems to remain that biofuels can be a significant niche product especially in good farm country, but not much more, absent some process at least as complicated as solar panels and probably finicky and vulnerable to biological plagues (e.g. algae in tubes.)
Well, my back of the envelope is that a forest, managed as an energy/pulp crop, can produce 20t/ha of dry matter per year. Actually, many produce twice this, but those are outliers.
The energy density of dry wood is 20GJ/t, so we have 400GJ per year.
if we assume a solar insolation of 5hrs/day (temperate regions) @ 1kW/sqm we have 1825 full sunlight hours equivalent per year, or 18,250MWh per ha per year. There are 3.6GJ per MWh, so this is 65700GJ
As a %, we then have 400/65700 = 0.6% captured by the trees.
For corn, the amount they capture is higher, C4 plants are very efficient, but they don;t do it all year - but you could double crop,in some places.
The 1% is probably right, but the 0.1% for forests is not.
BTW, the best practical yield for algae, in real open ponds, is about 3-4%.
How we use the energy is a different question, of course. Biomass has the special property that it is stored energy, PV is not, so biomass can do some things that PV can't.. Of course, we can take it further to make liquid fuel, but we lose more than half the stored energy in doing so.
The equation for biomass compared to solar gets more favourable the higher the latitude and rainfall. Temperate zones are only average for solar, but they are great for forests! And there are things that live and grow in forests that you can eat - this is not true with PV.
Newsflash: The vast majority of our future energy will necessarily come from contemporary solar captured by leafy plants.
Newsticker: all human energy comes via this path.
Newsticker: PV mounted to the previous unused buildings makes more sense than trying to make buildings "healthy soil & perennial vegetation."
Except for solar PV, solar thermal, wind, nuclear, hydropower, tidal power, geothermal, nuclear....
Yeah, if you ignore all the rest, you can say that's true.
I think his point was that people are solar powered as essentially all our food comes from plants. Therefore, civilization, being the totality of humanity, is also solar powered at the most basic level...
E. Swanson
From the Wikipedia article:
See: O'Neill, Gerard K.; Driggers, G.; and O'Leary, B.: New Routes to Manufacturing in Space. Astronautics and Aeronautics, vol. 18, October 1980, pp. 46-51.
Note 3 things:
Before you conclude that I must be a kook for suggesting such a far out proposal, I further suggest you read this.
Thank you for posting such an interesting article.
I think you are making life a little bit too hard on yourself by trying to compete with coal in the USA at 2c per KWh.
In the UK our wholesale black power prices (delivered at some notional point on our power grid) are about £50/MWh with the forward curve looking more like £60/MWh. On today's exchange that is more like 8 to 10 c per KWh. OK that price is slightly inflated by the European carbon scheme but it is actually mainly driven by the high price that we pay for imported coal and gas.
That price is for black (non-renewable) power. Renewable energy benefits from additional subsidies of about another £80/MWh for solar (130c per KWh). Strictly speaking your scheme should not qualify for that as it they have to be located on UK territory, but believe me, the UK government would be more than willing to negotiate with you on that.
The situation is similar across most of Europe. Why are you wasting your time in the US? Your idea will be 10 times (literally) easier to pull off in the UK. Welcome.
"making life a little bit too hard on yourself by trying to compete with coal in the USA at 2c per KWh."
I am trying to make this project still make sense even if someone comes up with some other really low cost energy.
"Why are you wasting your time in the US?"
I don't expect it to be done in the US, at least not before it becomes the major energy source for Japan, China and maybe the EU.
I have been asked to discuss it in Europe this summer.
"I am trying to make this project still make sense even if someone comes up with some other really low cost energy."
I have mixed feelings about that. If you really believe in this, you will seek the shortest and easiest path to making progress. Worrying about future competition is someone else's problem. As far as society goes, I would class that as a "good problem to have", although your investors might take a slightly dimmer view.
Can I just say, I really admire the way you have calmly and rationally responded to some pretty vitriolic doubters. We need people like you who think and dream big; we also need the doubters to keep our feet on the ground, make us smell the coffee and just occasionally install a sense of pathelogical desire to succeed just to prove those b******s wrong, without which no one has ever achieved anything really special. The two sides are in balance, but I think you've conducted yourself in a way that is truly several cuts above the other side today, very nice to see.
I am more concerned with solving the energy problem than this particular way of solving it.
I took about a year and a half off this power satellite to look into www.stratosolar.com
It looked like it might be able to be built for $1.2 B per GW, which translates into 1.5 cents per kWh.
It's still possible since while we found lots of problems we found solutions to them. But it reached the stage where the engineering problems were worse than power satellites.
Amateurs. I have been subjected to much worse.
yes, I for one was never a good salesman. That's probably because I have great respect for the truth.
As for your "Stratosolar" system, I suppose you did do aerodynamic calculations of the drag on the tethering cables. The drag coefficient for a round cross section cable is quite large, thus the horizontal forces due to wind integrated over a 20km length cable are likely to become rather large even without storm conditions. The design wind speed on my house is 80 mph and that is at ground level and within the boundary layer...
E. Swanson
It's not just a cable but a 30-50 meter diameter light pipe. The horizontal force is millions of newtons, even with rotating aerodynamic shrouds. But that's not a problem as long as the excess buoyancy is 4x the maximum wind force it will not lean over more than 15 deg. I almost wrote an article about it for The Oil Drum, and might still do one but there are even more engineering uncertainties than power satellites. And then you get to the governmental objections. Aircraft can fly through a microwave beam. They can't fly through 1/4 square meter of steel wire or the equal in Spectra cable.
It's a *much* smaller program to get started, but still way beyond the means of those who are working on it.
I am more concerned with solving the energy problem than this particular way of solving it.
Really?
Then why do you not comment on other topics on TOD?
Todd, Ghung, Darwinian and others have all put in their input on other topics and thrashing out the "energy problem".
Your track record is on TOD is about using space based power.
Really. I spent a year and a half on StratoSolar before getting bogged down in engineering problems worse than power sat transport.
Would it accomplish anything useful?
Do they know what to do? If so, where is it?
Not exactly. They have been on ways to get the economic and energy cost of getting to GEO down to where power satellites make sense.
Your track record is on TOD is about using space based power.
Not exactly.
The users of TOD can read your posting history to make their own determination if you are lying or not.
Given the bulk of your posts show up to post optimistic observations about space based power - others can decide for themselves how honest you've been.
I agree that using lunar material might be a better approach.
It's largely a psychological problem in that beyond a certain number of steps it's hard to get investment in a project.
In any case, a low cost transport to GEO (and beyond) will make everything, including moon mining and Mars missions easier to do.
Incidentally, a lunar elevator out through L1 looks like it might be a better approach than a mass driver.
Certainly, Earth launch is critical and anything to bring that cost down is urgent.
For the limited case of lunar materials, hopefully the Google Lunar Prize will overcome the main psychological barrier: "Access to the moon must involve a national program!" Moreover, if something like the E-Cat comes along and offers $0.01/kWh baseload electricity, it may be necessary to do both the laser launch and lunar space elevator in order to compete. (Your point being well-taken about the mass-driver.)
My skepticism echos, loudly, some of the above views on this, and my direct experience with lasers, microwaves, energy conversion, vacuum systems, and general engineering let's me point out some of the probably deal-killing challenges, despite it being an idea that has a good deal of gee-wiz technical appeal for me.
But let's stipulate for now that it works, economically and technically.
What does that do to our total population number and its impact?
For example, would it mean we could go to 20 billion people with such an abundant energy input? I do not think the over consumption and choking waste problems from abundant fossil fuel use is something we have figured out how to avoid or mitigate. An order of magnitude increase in our energy supply would seem to bring with it comparable increases in impacts.
Yes, you are right. The root issue is human population levels and how to control them.
Accepting that argument makes all technological improvements meaningless.
That only leaves the nightmare or truly magical solutions.
I point out a significant overall problem in principle with a particular, huge, technology. Lots of other technologies -- basic, advanced, and yet to be discovered -- can have clearly net positive outcomes. But not all of them. We need to chose our mega-projects wisely, if we go that route.
Your concluding assertion reads to me as a mix of the fallacy of the excluded middle and a set up of false choices.
So is the problem that this is an energy source for humans? Clarify please.
Yes, I think that abundant energy from such a technology would be a problem. That assessment is based on our specie's previous behavior with new energy sources and on our numbers already at least around carrying capacity.
That technology would solve a problem different from the main ones we and our children now face.
No, it leaves a global no population growth policy enforced by the UN or some other global organization with enough teeth to make it stick. Are you placing this in nightmare or magical or not considered?
I would say the nightmare would be 80 million people starving to death each year. I would say magical is we leave it to mother nature expecting the garden of Eden. I would say humane is a global forced two child policy enforced by a military force. A global force that has the authority to remove national governments that are not in compliance and impose a national government that will be in compliance.
"What does that do to our total population number and its impact?"
Not having some way to replace fossil fuel is likely to have a rather negative affect on population number, wars, famines, epidemics and such ending with a population of perhaps a billion and a rather radioactive earth.
"we could go to 20 billion people with such an abundant energy input?"
It doesn't look like this would happen, for reasons that are not entirely clear the population looks like it will peak under 9 B.
"An order of magnitude increase in our energy supply would seem to bring with it comparable increases in impacts."
If it were done by burning fossil fuel, I agree. But as energy sources go, this is about the cleanest you can imagine. With enough energy, we could sort out the waste from civilization into useful materials and considerably reduced the impact of humans on the planet.
If the transport cost gets down low enough, people could move off the planet. If enough did it, it would ruin the real estate market.
The cleanliness of the energy technology itself is of course important, but what is done with energy matters as much or more.
Suppose we switch to an energy source without a carbon problem, and we peg the population near 9 billion. My understanding of the resource numbers is that if we raise most people's living standard to a modest western european one, then perhaps we have the acreage for just some few billion. Thus, 9 billion reaching for a higher economic level seems like it could easily get into plague-of-locusts territory.
We have exactly one planet, with no backup. Running an uncontrolled experiment near plausible limits of carrying capacity just strikes me as profoundly foolish.
And many of the carrying capacity arguments aim at finding the maximum sustainable. This unsettles me as it seem prudent to throw in at least an engineering-factor-of-two as a safety margin to account both for what we do not know and for fluctuations. I actually suspect that a factor-of-ten margin may in fact be more reasonable.
"We have exactly one planet, with no backup. Running an uncontrolled experiment near plausible limits of carrying capacity just strikes me as profoundly foolish."
For sure. Problem is that we are almost certainly way over the carrying capacity limit without using mega amounts of fossil energy that *will* run out.
Clean, cheap energy would let us make fresh water out of salt and pump it inland a thousand miles to grow food.
If the transport cost gets down low enough, people could move off the planet.
Here's where Keith tips his hand. Move off the planet to where? And who would be willing to do that?
Reality is complex and messy and interwoven and, yes, REAL. Beaming electricity down from space is never going to be anything but a gimmick, if that.
9th Grade Science Club project plans aren't going to save us, alas.
Rotating cylindrical habitats about 5 miles diameter and 20 miles long. A good place to start reading is here.
I have no reason to believe that the global population will stop at 9 billion if we can provide clean air, water and land to all and good housing, food, water, medical, education to all.
From FERTILITY IN ISRAEL: IS THE TRANSITION TO
REPLACEMENT LEVEL IN SIGHT?
Dov Friedlander
* Department of Population Studies, The Hebrew University of Jerusalem, Israel.
"Hence, the socioeconomic structure of the ultra-orthodox population, its internal educational system and its
political power within Israel’s society, are conducive to its survival as a high fertility group whose
families conform to community norms of early-universal marriage and high continuous fertility."
The fertility rate of this group is 7.0
Religions are evolved behaviors that contribute a great deal to the evolutionary fitness of those who practice them-when the crunch hits, the more numerous the ultra orthodox, the greater the likelihood of SOME of them pulling thru .
The fact that a crunch IS coming, from the "viewpoint " of evolution is irrevelant.
Evolution doesn't possess a value system, or give a damn about what happens, being a non living statistical phenomenon.
Going for it, population wise, is pretty much par for the course for all living things.
Humans have long since reached the stage at which most of our competition for survival is intraspecies.
This is not likely going to change-even after the crunch hits.
We are likely to continue to be our own worst enemy.
I will take this opportunity to point out the fact that my extended Baptist fundamentalist family has over the last three generations reduced family size from about six per woman to somewhat less than two currently.
We are going to die out pretty soon unless we get serious about going forth and multiplying.
I don't know whether this cause me to should laugh or cry.
Evolution's experiment with intelligent tool users has reached an interesting point. We've managed to invent civilization and for the most part we cooperate remarkably well. But beneath the veneer, we are still "naked apes". We pursue our own advantage relentlessly, but are adept at rationalizing. We find reasons to justify war on those who occupy lands or control resources that we covet for our own.
What's fascinating, however, is that in honing our abilities as tool users, we've invented the arts, science, and philosophy. We actually have the capacity to experiment, analyze and understand what makes us tick -- though precious few of us are inclined to go there. But the capacity to understand is in us. And with technology, also the capacity to change ourselves. It's taboo, but we have, or soon will have, the ability to become the next step in evolution: "self-designing man" -- whatever the Latin for that would be. We could choose to make ourselves truly civilized, not just pirate apes sailing under a false flag of convenience. If we do that, then uncontrolled population growth will not be an issue.
Whether we'll manage that transition is by no means certain. It's possible -- even likely -- that the evolutionary experiment that will fail, that the war god will triumph, and that our vaunted civilization will fall to the four horsemen. I don't know. But one thing I am fairly sure of is that we cannot go back. We can't return to the ways of our great grandparents, however much we might think we desire it. There are too many of us.
I'm less certain of it, but still pretty sure that we also can't go forward directly to the sort of post-oil, energy-efficient "ecotopia" that the Greens are hoping for. That might be a fine target eventually, but I don't think that that style of living can accommodate the billions now on earth, and the billions more who will soon be joining us. The only direct road to the Green's dream runs through massive dieoff, and that way is the death of all dreams. It's not in our natures to go peacefully, and the raw savagery that dieoff will engender will not spare dreamers.
When a woman is screaming in the pains of labor, she may strongly wish that she had never become pregnant. But it can't be undone. The only way out is to complete the process and deliver the baby. In my opinion, the only hope we have of avoiding destruction and breakdown is to press on, into the post-human future that awaits us on the other side of the birth canal. We need to develop energy resources that will enable the world's billions to feed themselves. We need to raise education and living standards worldwide, promote universal justice, and eliminate as much as possible the causes of war and what we conveniently label as "terrorism". We need to create worldwide the conditions that have led to demographic transitions in the advanced nations.
It's in that context that I view satellite solar power. We need abundant energy if we are to stand a chance of building the kind of world that will see us through E. O. Wilson's "bottleneck" of the coming years. Yes, there's a huge potential to reduce energy consumption through better efficiency in heating, cooling, and lighting our buildings, and in transporting our goods and our selves. But those reductions pale in comparison to the increases we will need to address the food and water crises and improve living standards worldwide. So the question is, how can we supply that energy most efficiently, with the least impact to the land and life around us. Satellite solar power is a possible answer, but hardly the only candidate.
Well said.
Well stated.
It is one of only a few that scale into the range of human needs.
That we know about that is.
David MacKay discusses the problem in _Sustainable Energy — Without the Hot Air_.
http://en.wikipedia.org/wiki/David_J._C._MacKay
StratoSolar might do it, but it seems to be a harder engineering problem than power satellites.
It is one of only a few that scale into the range of human needs.
The last time you showed up to 'discuss energy solutions' it was shown PV gets 170 W/m2 and the space boondoggle at 300 W/m2.
I also pointed out small black dots on the globe to use PV to capture ALL of Man's energy needs.
http://www.theoildrum.com/node/5306#comment-494573
PV can scale. But Man can lower the energy demand also.
The beauty of ideas that "threaten" to provide cheap, low environmental impact energy is that it brings into sharp focus the problem of civilization:
Unlike a sexual organism, civilization is a meta-organism that simply grows to consume all available resources.
I've been around environmentalist for almost my entire life, starting as a ZPG member in 1969, so I'm more than familiar with the moral vanity infecting the culture -- moral vanity that is quite happy to play "church lady" but never get down to the nitty gritty of what their moral vanity really means to humanity.
Earth should be reserved to a state of nature, meaning that if humans want to live on Earth, they have to agree that anyone, not formally shielded by another individual, if challenged to natural duel must either enter at the opposite end of a sizable and varied wilderness area, to the challenger, there to kill or be killed, or -- if they decline the challenge -- simply be killed by mob action.
Space, on the other hand, is quite capable of supporting virtually limitless growth of civilization. Now, this doesn't mean I think that is a good idea, but its got to be a hell of a lot better than the world to which the church ladies of environmentalism will doom us with their self-indulgent moral vanity displaying their "Godliness".
Well, I know how annoyed people get with the Greens, and really do understand the resentment pointed at them.. but really anyone who is trying to pull things back together that seem to be falling apart has their own brand of "Godliness", don't they?
The assmptions of available power, technology and capital that this author has built into his assumptions of a 'doable' project, and then beaming this omnipotence down from the heavens with it, to bless us all.. I'm afraid the thought of 'Playing God' is heavily infused in this Rational Fantasy as well.
Some greens go too far, no less than anyone else.
"Character is Destiny" - Heraclitus
I recall when Pons and Flieschmann made their Pd+D anomalous heat announcement Paul Ehrlich said something to the effect that "This is like giving a 3 year old a machine gun." The recent news about the E-Cat's possible revival of such dreams is being met with the same responses.
That's OK so far as it goes. I'm with them. It is horrible to contemplate what a global civilization with 9 billion cells wielding unlimited personal energy would do to the planet.
OK, so now what?
That these children continue to play parent and refuse to grow up is what annoys me. It hardly matters whether or not the proposed energy solution is "Playing God". Let the marketplace decide who is having "Rational Fantasies". That's not the problem. The problem is the folks who pretend to be protecting the planet and refuse to deal with the real problem:
Civilization.
Its got to go.
'Children playing Parent' ??
What has BP been playing? Are they the adults? Did the Market choose these Gods wisely?
Tepco?
Massey?
The market is fine with them.. the market isn't the system which has to keep those -ahem, Children in line.
I think they're acting out cause they privately WANT a daddy and a mommy to shoulder some of the responsibility.. no?
Clarifying:
The "market" is a creature of "civilization" and "civilization has got to go".
The question is, "Where?"
At least Henson has an subtextual answer although he doesn't directly address what is to be done with the grey goo now eating Earth in the meantime. There are worse things than letting the market decide to go for a silly looking energy technology as long as it at least temporarily reduces the rate of the grey goo's destruction of Earth; and -- feasibility aside -- the argument for raining microwaves down on Earth as a temporary "fix" for the grey goo's growing energy addiction has some obvious short to medium term benefits. Its sort of like we have a junkie adolescent flying an F-16 looking for a fix. Maybe it wouldn't be a bad idea to feed his habit for the time being.
Thank you Keith for your article, and Gail for sponsoring it.
I find it good for TOD to explore the corners of the energy production/usage phase space, even if the topic at hand has an exceptional low probability of success.
At least Space-based power systems do not require any 'breakthrough physics'.
It is in the realm of technical possibility, but in my opinion far outside the realm of large-scale engineering and economical feasibility.
Skylon is a paper airplane, and its cargo bay is small. Although we have been clever about building small numbers of small-scale extensible, unfolding, unrolling gadgets (antennas, structural beams, solar panels) there is a RDT&E cost and an operational complexity risk associated with that approach.
As a previous poster said, perhaps a large payload volume rocket such as Sea Dragon would be more appropriate for lifting large structural components to orbit...if the costs were sufficiently low, and I doubt that will ever be the case.
http://en.wikipedia.org/wiki/Sea_Dragon_%28rocket%29
To really take no prisoners, one could look at the Orion concept:
http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29
Oops, there is that little issue of a nuclear exhaust!
Honestly, I agree with the numerous other posters here that the fielding ans sustainment challenges to this idea are legion, and insurmountable, when looked at through the lens of economic feasibility.
The O&M costs and vulnerabilities to natural and man-made havoc are enormous.
Self-replicating machines on the Moon and in orbit building and maintaining these systems? Not going to happen.
Take the $100T such a scheme would end up costing and spend a fraction of that to mass produce terrestrial PV systems to mount on residential, commercial, and industrial roofs....build many more wind turbines...subsidize insulation/cool roofs, better windows etc for buildings to cut energy use...LED lighting for all...upgrade the grid, etc.
"The O&M costs and vulnerabilities to natural and man-made havoc are enormous."
We have hundreds if not thousands of unit-years experience with communication satellites.
A few of them have had electronics fried by exceptional solar events, a larger number have failed for a variety of reasons. Most of them have operated beyond their expected lifetime. Far as I know, none have been damaged by natural space junk, none that I know about have been attacked, not even the ground antennas.
So why should power satellites have enormous O&M costs?
The size of SBPS dwarfs the scale of communications/GPS/science satellites.
Besides the infeasible launch costs, the on-orbit assembly and repair costs would be huge.
Although electronics can (and are) made rad-hard, people are not...there is too much radiation exposure in geosynchronous orbit for hundreds of workers...let alone for you concept of having families live there for years.
In concept,robotics could be use for assembly and repair, but the costs again would be huge.
You are greatly underestimating the complexity and costs costs involved in this proposed undertaking.
Here is what I don't grok: It is somehow infeasible to put PV on most roofs, but feasible to build hundreds of enormous space-based solar power satellites?
"Besides the infeasible launch costs,"
That's what the article is about. If we can't get lift cost down far enough, then power satellites make no sense at all.
"there is too much radiation exposure"
Drain the Van Allan belt, stay behind shielding during solar storms.
"Here is what I don't grok: It is somehow infeasible to put PV on most roofs, but feasible to build hundreds of enormous space-based solar power satellites?"
It's a matter of cost, and that largely depends on the amount of material you have to invest.
Power sats are *much* lighter than ground installations, they don't have to cope with gravity or wind and they get a *lot* more sunlight. If someone can get the cost of ground solar down to 2 cants a kWh (including storage) then they win and power sats loose. Simple as that.
PV probably isn't the best choice for power sats.
Where do electromagnetic accelerators stand in relation to shooting the required loads into space? The cargo could probably withstand the forces.
http://en.wikipedia.org/wiki/Non-rocket_spacelaunch
http://en.wikipedia.org/wiki/Mass_driver
http://en.wikipedia.org/wiki/StarTram
http://upload.wikimedia.org/wikipedia/commons/thumb/c/c0/Maglifter1.jpg/...
It is electric.
KalimankuDenku,
thank you for posting this...I am curious whether Keith considered this potential approach.
Perhaps EM launch, combined with a small on-board rocket to achieve LEO, then illuminate the payload module engine with LASER energy to achieve geo orbit?
At the launch rates he envisions, numerous of these launch systems would be required.
All this being said, I fear the costs of these launch systems would be a deal-breaker, in addition to the other costs of the entire geo space power sat enterprise.
Not good, attaining high speeds where where the atmosphere is thickest makes for very high aerodynamic and thermal loads wich makes structures heavy if they are to survive them and also gives high energy losses.
I prefer well run companies with traditional rockets such as Space-X and then I have the highest hopes for two stage systems where first the booster stage and then both are made reusable. It is not good enough for space based power but enough for more communication satellites and research.
If they would make sense anywhere, building power sats would be it.
Unfortunately they don't. It's been years since I worked out the numbers though so I can't give you the detailed answer as to why they don't, but it is the cost which is due to the extreme power they draw near the ejection end.
Something new every day - this bit is a new one on me. The Wikipedia article tacitly assumes that the rectenna array would be fenced off like an industrial site.
A power level of "1/4 of sunlight" (an obfuscatory formulation as irritating as the unit of electrical power called the "house") would be about 250W/m2, or 25mW/cm2. And that would be whole-body exposure, to a farmer working there. Now, the rectenna array will presumably absorb most of the radiation, since that's the point of building it. But some will get through, if the array is mostly empty space so as to let sunlight through. 5%? 15%?
By comparison the usual microwave oven standard, the subject of which is transitory incidental exposure to much less than the whole body, is 5mW/cm2 for the user, and in some locales just 1mW/cm2 for bystanders (see here). And IIRC there was or is a Swedish standard of a mere 50μW/cm2 for the (somewhat different) emissions from CRT monitors. And there's the issue of induction of cataracts in the eye. Enforceable occupational limits for microwave radiation in general are a real mess in some countries, but I suppose this sort of thing could finally force the issue.
Oh, and then there's all the fuss over "cancer" from cell phones.
Put all that together, and I'm having a lot of trouble picturing the local farmers working their land underneath such arrays. No, let's be honest, I'm having trouble keeping from falling off my chair laughing. There may be a real microwave hazard, there certainly are imaginary hazards, and the political gallery will go ape over both, guaranteed. Then there's the question of cluttering up the farmland with supporting structures, and the question of what happens, with all those live wires overhead, should a tractor, or combine, etc., ever accidentally snag one of the supports. (If the load is suddenly disconnected, the array presumably stops absorbing, and our farmer gets the full blast?)
If the rectenna arrays are simply treated as industrial sites and fenced off, as in the Wikipedia article, it might be a whole 'nother story. Though there would be roughly as much land to fence off as would be shaded by on-ground solar panels.
There is plenty of dead worthless desert in California. No need to put receivers on good farm land.
Right, and not my idea, but from the keypost:
...so there must have been some reason, such as some sort of political palatability, to propose putting them on farmland. We could certainly spare enough marginal land or desert for all the area we could ever need at 250W/m2, although somebody would for sure howl about it.
The point is that the rectennas are mesh structures that block microwaves to the ground below them, but don't block much sunlight. So it's perfectly feasible to use the land below for agriculture. In practice, they would be located wherever it was most economical to do so, considering transmission lines and cost of land leasing.
dead worthless desert
There are things there - things like Gila Monsters or Horned Toads that don't exist in, say Minnesota.
Just because these things (And others) are not as "valuable" to Man as say, Cows or veggies, that doesn't mean the land doesn't have some critters there and some level of genetic preservation is not needed.
Almost 0%. A mesh with holes much smaller than a wavelength appears as a solid conductor and transmits radiation as (IIRC) an exponential function of its net conductivity with a negative exponent.
You can see through the mesh in front of the window on a microwave oven; it's safe for bystanders, and the incident power level is tens of kW per m². A rectenna's job of shielding what's below it is far less difficult.
I don't understand how someone can remotely think that this thing might work. I have been an system engineer for instrument for weather satellite and I was one of the first to work on the James Webb space telescope concept. And, IMHO this space power will never happen this century.
-First, you need 3 order of magnitude reduction in space launch cost. To do that, you need a ridiculous launch rate. This launch rate means that a lot of stuff will be in orbit, which alone will create a huge problem of orbital debris.
-You need also a 3 order of magnitude increase in space power from the actual technology
-Radiation pressure is far from being a trivial problem. This does not cancel out over time, you must correct the orbit all the time. There is a gravity gradient at GEO orbit that makes satellite drift. In addition, you must track the Sun. This means that the whole thing must turn around.
-Mechanically, this solar collector will be a pure nightmare. In space, vibration do not dissipate easily. Vibration mode are awful and must be corrected.
-Energy transmission method is bound to have loss. This will create a huge thermal dissipation problem. In addition, energy transmission itself, will create a radiation pressure that would need to be compensated in some way.
-Lifetime of solar cell. In orbit, you are subject to radiation. This is even wort in GEO. Your solar cell age rapidly. This is not taking account of the orbital debris that will damage even more the solar collector.
-Going to the Moon might be cheaper in theory. But nobody as any idea how to work in the lunar environment.
This is pure sci-fi.
"First, you need 3 order of magnitude reduction in space launch cost"
Close, $20,000 down to $100, a 200 to one reduction. The Falcon Heavy launched once an hour would probably get to a 20 to one reduction, but that not enough for the target price.
"You need also a 3 order of magnitude increase in space power from the actual technology"
I am inclined to thermal type power plants at 60% over PV at 15%. Thermal units would probably not be much larger than 25 MW and those are already made in large numbers (aircraft turbines).
"Radiation pressure is far from being a trivial problem. This does not cancel out over time, you must correct the orbit all the time"
For very light satellites it is a problem, at near zero the light pressure would blow them away like a solar sail. But at 5 kg/kW, the accumulated acceleration is only a few hundred meters and it is canceled out over a year. The correction for light pressure on a communication satellite is nearly zero.
"In addition, you must track the Sun. This means that the whole thing must turn around."
Right. The concentrator must track the sun, the transmitting antenna must point at the earth. There are a number of ways to do this.
"Mechanically, this solar collector will be a pure nightmare. In space, vibration do not dissipate easily. Vibration mode are awful and must be corrected."
The biggest problem is the shock from going into the earth's shadow around the equinoxes. It's serious enough that Invar might be the material of choice, alternately active damping.
"Lifetime of solar cell. In orbit, you are subject to radiation. This is even wort in GEO. Your solar cell age rapidly."
A good reason to go with thermal designs. Also there are proposals to drain the radiation belts.
"This is not taking account of the orbital debris that will damage even more the solar collector."
There is very little dangerous debris at GEO. It's all moving the same way at low relative speeds.
Thermal/mechanical power systems?
Wow, now you really are tempting the vibration demons!
OK, you have now jumped the shark.
At first I gave this discussion the benefit of the doubt, but in your answers to posts here I see a lot of arm waving and no math/engineering.
When I see detailed, complete designs in CAD programs, with all the appropriate finite element analysis and dynamic analysis of loads/stresses, and material and design aging studies, and a thorough cost accounting vetted that is open-source, so that any number of folks can vette it, then I potentially may be interested.
"Wow, now you really are tempting the vibration demons!"
Why? Hubble has neon refrigeration compressor and I am sure it doesn't introduce much vibration.
" Also there are proposals to drain the radiation belts.
"OK, you have now jumped the shark."
It's not even my idea.
"The belts are a hazard for artificial satellites and are moderately dangerous for human beings, but are difficult and expensive to shield against.
"The physicists Robert P. Hoyt and Robert L. Forward proposed the concept HiVOLT (High Voltage Orbiting Long Tether) as a potential means to drain the radiation belt of high energy particles. The proposal involves deploying highly electrically charged tethers from satellites in orbit. Charged particles within the radiation belt encountering these tethers would be deflected by their large electrostatic fields onto paths that intersect with the atmosphere, where they would be harmlessly dissipated.[17] Simulations have suggested that the inner belt could be drained to 1% of its natural electron flux within two months of HiVOLT operation.[18]"
# ^ David, L. (2002-09-16). "Proposal: Removing Earth's Radiation Belts". Space.com. http://www.space.com/scienceastronomy/radiation_belts_020916.html. Retrieved 2010-03-09.
# ^ "High-Voltage Orbiting Long Tether (HiVOLT): A System for Remediation of the Van Allen Radiation Belts". Tethers Unlimited. http://www.tethers.com/HiVOLT.html. Retrieved 2010-03-09.
http://en.wikipedia.org/wiki/Van_Allen_radiation_belt#Removal
"At first I gave this discussion the benefit of the doubt, but in your answers to posts here I see a lot of arm waving and no math/engineering."
If you could, please point out where I have been asked a question that required more than grade school math.
Nobody has said a word about the effect of high exhaust velocity on mass ratio.
At GEO this issue is not radiation belt it is high energy proton from the Sun and cosmic rays. The only solution is shielding.
Hubble as a Neon refrigerator, which as a low thermal efficiency by the way, coupled with a thermal radiator. Obviously, you don't understand thermal engineering. PV could be made more or less self cooling with some care. But thermal power need huge heat sink. And to manage the power requirement, you will need some kind of cooling loop, that are leak trap.
"Obviously, you don't understand thermal engineering. "
I am an electrical engineer. Thermal problems are the bane of our existence.
However, I do know something about thermal engineering.
Henson, H.K., and K.E. Drexler: Gas Entrained Solids: A Heat Transfer Fluid for Use in Space Space Manufacturing AIAA 1979
The article was reprinted in the L5 News in 1979 if you want to read it.
"But thermal power need huge heat sink. And to manage the power requirement, you will need some kind of cooling loop, that are leak trap"
Indeed they do, two square km per GW (1/4 kW/m^2 is the engineering rule of thumb for space). That's less area than the solar concentrators. The system mass minimum for Carnot cycle engines with a top temperature of 1400 C is around 130 C. If you want to see the calculations I can send them to you or maybe figure out how to post a graph from Excel.
Most SSP designs collect the energy with PV.
Keith usually seems to envision mechanical systems for SSP energy collection. No satellites in GEO or cis-lunar space use mechanical systems for energy collection.
The only mechanical systems in cis-lunar space are used for refrigeration, attitude control, etc., not energy collection - too high a failure rate and you can't repair them in situ.
RTGs, which are mechanical, are only used in DEEP space probes beyond Mars orbit, such as Voyager or Cassini.
RTGs are not 'mechanical', if you meant to use the word 'mechanical' to signify a device which has moving parts. Thermocouples convert heat from a substance such as PU238.
Putting large numbers of gas turbines into geosynchronous orbit is impractical. The maintenance costs for hundreds of power sats with perhaps thousands of turbines over a 50-year+ lifespan would be unfeasible.
With a turbine / magnet alternator-half as the only (substantial) moving part aside from the working fluid, and that potentially suspended on non-contact bearings, I fail to see the maintenance issue. Such devices could easily have mean times to failure in the decades to centuries range. Further, the collector is modular. If one fails, it just quits. Then you replace it using the same technology you used to install it (and potentially tow the failed module to an in-orbit refurbishment site in lieu of launching a replacement, if that's easier than repairing it in-place).
A thermoacoustic heat engine could replace the moving part with a diaphragm flexing at well below the amplitude which produces substantial fatigue. (Unfortunately, current thermoacoustic designs aren't as efficient as gas turbines.)
The turbine / magnet alternator...suspended on non-contact bearings...has this technology been demonstrated on Earth?
Has a Mean Time Between Failure of decades-to-centuries been demonstrated?
Has anyone run a detailed design of a thermal solar space platform with enough capacity to beam huge amounts of energy down to earth through a dynamic analysis program? what are the vibrations? What are the torques involved on the orbiting platform?
Witness the fidadling NASA has gone through to keep the ISS running...look at the trouble with the 'Alpha' solar panel rotary joint. Also look at the Mx issues with the Ammonia coolant system.
Multiply these difficulties by 1 x 10^6 for the discussed fleet of geosynchronous space-based solar power platforms.
How much will ISS cost over its lifetime (through ~ 2025 at best)? $100 Billion USD? How much power does it generate? Does it beam any to Earth? Is it in geosynchronous orbit? Does it come with a kilometer-diameter ground rectenna?
Lookit...I am not saying that this cannot be done...but I fear the life-cycle costs are being WAY underestimated.
And if we are hooked on this system, then we are required to maintain it in perpetuity, as others have said...
I wonder how much power ~ 1,000 1-kilometer-diameter terrestrial solar PV installations could produce?
In addition to covering most rooftops with PV?
Build a bunch of flow batteries with all the Vanadium we will produce as a by-product of Venezuelan heavy oil. Adjust our lifestyle to live with the fact that we won't have as much power available during nighttime.
Someone do a comprehensive life-cycle cost-benefit analysis of the geosynch solar scheme vs. a terrestrial solar power scheme which generates comparable power, within the limites imposed by the diurnal cycle/weather, transmission loses etc.
Has anyone run a detailed design of a thermal solar space platform with enough capacity to beam huge amounts of energy down to earth through a dynamic analysis program? what are the vibrations? What are the torques involved on the orbiting platform?
And what is the effect of the current induction of a CME on the platform?
How about the micrometeorites which WILL strike it?
Last time 'round no one had a good answer to the micrometeorites. Lets see if this time the supporters do better.
Todays Satellites are subjected to micrometeorites they operate for a decade or more with, as far as I know, no ill effect.
Do you have some information on degradation of their performance?
I've no doubt that before anyone puts in the billions to deploy these things they'll put in the millions into designing them, those designers will study the sorts of points you raise in detail, though most of your points have already been addressed in todays engineering of thermal stations, or are irrelevant strawmen, for example: why shouldn't ball bearing be adequate?
I think you're suffering from what Asimov called the nightfall effect.
In space it takes only a VERY small part of a constant rotational movement transferred through the bearings to impart rotation to the structure, yet another force to be cancelled out. In a failure, which will happen frequently given the number of units involved, you will have large rotational forces applied to the structure needing cancelling.
NAOM
Angular momentum of the whole structure will remain constant, you seem to be suggesting that friction in the bearing will cause a problem with ever increasing angular momentum.
Why this obsession with bearing failing?? They last for decade in cars, and the forces on bearing with a structure in zero g are going to be very small
Today's thermal stations are not transported to, assembled in, and operated for 50 years in geosynchronous orbit.
Large PDF warning: ISS Solar Alpha Rotary Joint Anomaly
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20100003841_2010003...
Article about ISS Ammonia cooling system leak and repair:
http://www.cbsnews.com/network/news/space/home/spacenews/files/8d365873b...
The minimal moving parts and minimal plumbing in a PV-equipped powersat strikes me as a big plus.
The fact that terrestrial PV does not have to be lifted up the gravity well and can be installed and maintained by reasonably skilled folks who are not either astronauts or robots strikes me as a plus as well!
I 'suffer' from years of seeing contractors and government program managers over-promise and under-deliver, poo-poo risks, make unsubstantiated, overly-rosy assumptions, and greatly exceed budget and schedule and end up having to accept lesser performance, for the programs that don't get axed first.
I notice that Keith Henson as nothing to say about the ISS joint problem. Perhaps it's just another technical hurdle to him, one which will be easily solved by those great aerospace engineers out there hiding behind their DOD clearances.
But, looking at the NASA report on the rotating joint problem, consider this. The size of the space power satellite can be expected to be considerably larger than the ISS (we don't know, do we?), thus it's reasonable to assume that the necessary bearing assembly(s) would need to be proportionally larger. The ISS joint is 3.2 m (10.2 ft) in diameter and has a mass of 1,161 kilograms (2,561 lbs). The payload bay in the proposed Skylon ship is 4.8 meters in diameter. Thus, a slightly larger joint assembly would not fit within the Skylon cargo bay. Next???
E. Swanson
I thought someone else's comment about bearings was hugely entertaining!
"Why this obsession with bearing failing?? They last for decade in cars, and the forces on bearing with a structure in zero g are going to be very small"
Obviously someone who has never, ever worked with bearings in high vacuum.
I look forward to your words of wisdom as to why slow rotation joints are such a problem in a vacuum
Lubrication, wear, sticking
Use gold or ceramic or fluorine polymers or moly disulphide
Reconfigure design/eliminate bearing
https://project-wire-scanner.web.cern.ch/project-wire-scanner/Notes/Bibl...
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19640001328_1964001...
Probably the biggest challenge with bearings in space is the temperature range that they can be subjected to, on a SPS, because it's in constant sunlight, improved opportunities exists to use methods to protect bearings from such extremes, active temperature control, or insulation combined with light diffusers and reflectors.
You can buy one. Capstone gas turbines run on air bearings.
From the Space mission design and analysis and assuming 0.5 kg/m^2, I got 1,4 km/s per year. This is hardly trivial even with ion thrusters. This only cover the radiation pressure. There is also perturbation from the Earth gravitational field, Moon and Sun that need to be covered. And no, this is not cancelling out. Over a year, your orbit get more eccentric. You need to do orbital correct to avoid any drift.
If you have a thermal generator would will need a heat sink as large as the solar collector to evacuate the heat. This is not a trivial issue.
As for the launch cost, you have to use GEO cost, not LEO cost. GEO is around a factor 5 more expensive.
As for risk of collision in GEO even slower speed is still very fast. A few tens of m/s might not look much but this is more than enough to blew a hole in your solar cell. And that's to the virtue of radiation pressure and other orbital perturbation, fragments return at a similar speed.
Please reread the article. Getting the cost to _GEO_ down to $100/kg was the major point.
How many kg/m^2?
1.366 kW/m^2 x 60% efficient x 50% transmission loss, .4098 kW/m^2
So the area for a kW would be 2.44 m^2, the mass is 5 kg/kw so the sectional density of a power satellite that heavy is just about 2 kg/m^2, which gets your yearly velocity accumulation down to 350 m/s, or 30 m/s per month but the direction is radially out from the sun. Over the course of a year the forces balance out and the light pressure gets transmitted to the earth. In the context of a 3.07 km/s orbital speed it isn't much.
No, this is not averaged. This increase the excentricity of the orbit. And 350 m/s is a large fraction of the orbital speed. If not taken into account this you bring the excentricity around 0.1 on short notice.
I go for PV (40%) with Fresnel lens.
http://slasr.com/Papers/SpacePaper5.pdf 300W/Kg
http://greening-aiken.wikispaces.com/file/view/Solar+Concentrator+Arrays... 1000W/Kg
This is M. O'Neill not G. O'Neill.
"-Going to the Moon might be cheaper in theory. But nobody as any idea how to work in the lunar environment."
Well, until recently, you could have asked 12 guys how to work in the lunar environment. Unfortunately, Pete Conrad, Alan Shepard, and James Irwin have passed on, so that only leaves you with 9. Most of them have written books that told how they did it. Makes great reading, even for engineers.
Being on the Mooon for 48 hours collecting rock is not the same thing as effectively working there. My selves are full of space engineering book. I pretty much know how hard it si to do something in space.
"Is the surface of a planet the right place for industry?"
This was the question posed by Gerard O'Neil.
The answer is no.
Our industries blight the surface of our beautiful planet because we lacked the capacity to take them elsewhere.
But now we are running out of excuses. We have found a lot of water on the Moon. It is almost as though the Moon was placed there to encourage our baby steps away from the surface.
Meanwhile we are being whipped by the consequences of "Limits to Growth."
We have to leave. We either do it with a will, or a winge. But do it we must.
Orbital solar energy may or may not be our excuse.
Gerard O' Neil has lit the fuse.
We could go the path of a baby that refuses to be born, and there are an awful lot of people advocating for that.
Agree.
All, please find and read the short story 'Fecundity Unlimited' by Issac Asimov.
He used ludicrously optimistic/generous assumptions (space flight across the Universe, planetary/stellar engineering is a piece of cake, used C as the limiting element instead of P for humans, much more), and a rather low population increase rate, and calculated that the entire Universe would be converted to human mass by ~ 11,000 C.E.
Running off into space is NO escape from the tyranny of population growth.
Besides, running off into space en masse it is a net energy sink and infeasible with realistic engineering assumptions.
The only answer is zero-population growth and a total population within carrying capacity.
If one is of the mind that folks are going to transform into computer programs or beings of pure energy etc. then...have fun with those fantasies.
I wrote a paper just about that problem.
http://arxiv.org/abs/0711.1777
By the way, thermal pollution alone is likely to be an issue at the end of the century if the growth continue.
"Running off into space is NO escape from the tyranny of population growth.
Besides, running off into space en masse it is a net energy sink and infeasible with realistic engineering assumptions.
The only answer is zero-population growth and a total population within carrying capacity."
Yes. How do you see this happening on Earth? When do you see this happening?
OK, when you said 'Yes', can I infer that you agree that expanding completely throughout the known Universe is no escape from exponential growth? If so, we have a victory for logic!
Again, everyone read Asimov's 'Fecundity Unlimited' short science article, if you can find it. Unfortunately, being copyrighted, it is not to be found anywhere on the Internets and it was published many moons ago. I read it in a collection of short non-fiction works of Asimov.
Asimov used purposely ludicrously optimistic assumptions which have zero basis in attainable reality to make his point: Given the opportunity, humanity, increasing at any rate above zero percent population growth, would engulf the entirety of the know Universe in about 9,000 years. Fiddle with his assumptions all you want and the answers don't get much better, and realistic assumption indicate that the answer is much worse...
How and when do I see this happening?
Since most Humans cannot overcome their biological programming to pass on their gene's prolifically, I have little hope that we we adopt a zero-growth population paradigm.
Which means that we likely are doomed as a species to eventually overshoot and collapse, and experience some periodic repeat of this cycle until we go extinct.
I didn't say I was omnipotent...I just stated the obvious solution to the dangers of continuous growth...which is a zero-population-growth society.
Chatting about launching 60 tons per hour of mass to build scores of Terra watts of space-based electrical generation and transmission capability does not change the issues with unchecked population growth. In fact, pursuing such a venture would squander our dwindling resources and make things worse than they otherwise would be.
Oh? If my energy analysis is correct these things have an energy payback time of two months.
How can you say taking this course would make things worse? Are you making the case we should keep burning coal? Or are you saying my analysis is wrong? If the first I have nothing else to say, if the second, I would appreciate a reasoned argument against my analysis.
Hmmm...I owe you a little bit of clarification:
- If this concept would works as you describe, with a 2-month payback, and everything is feasible and hunky-dory, I would be all for it...I would be the biggest cheerleader the concept could find.
I am not making the case for burning more coal, oil, or even methane, nor for building more nuclear fission plants...at least until/unless we solve the issue of nuclear waste and make profound improvement is plant safety.
A caveat: I agree with others that even if we could engineer all the low-pollution energy we could want from orbit, we would still need to deal with zeroing out our population growth and our resource consumption and pollution production growth.
Also, my advocacy for a workable orbital solar power system in no way equates to any belief in or advocacy for the idea that humanity could colonize the Universe and therefore jettison any care about achieving zero population growth...see Fecundity Unlimited by Asimov.
I think the design and implementation of using microwaves to transmit the power with the losses you describe is possible.
I am not overly concerned about environmental harm from microwave transmission through the ionosphere and the rest of the atmosphere, nor would I lose sleep over the potential effects on people and animals, nor the use of land for rectenna arrays. It is conceivable that rectennas could be erected over farmland with little detriment.
I am not concerned about the embedded energy in the space-based power satellites...the metals, composites, etc, and the embedded energy in the rectennas and so forth.
I know that nothing you have proposed violates any laws of physics, or requires new materials such a miles-long diamond or carbon nano-tube fiber (see space elevators).
My objection is that I have not seen in your presentation, nor in supporting studies you have mentioned, anywhere close to sufficient engineering analysis details to convince me that the plan can be executed with the costs and commensurate payback period you describe.
Also, the nature of the exchange on this forum about this idea suggests that your vision is still formative...we seem to be talking about space-based PV, then mechanical turbines...first we talk of Skylons, then you say that 'any technology that can get the mass to geo orbit'...then the conversation bounced over to the idea of mining the Moon for materials...in some passages we talk of 500-1000 people in orbit, then we talk of 'well, we can use robotic systems if that proves to be the way to go'. This idea seems to be in the brain-storming stage, yet you respond to objections with great certainty of your solution expressed in vague terms.
Your characterization of people who have posted objections / criticisms to your plan as 'amateurs' is dismissive in a broad-brush way. Your statement implies that you have detailed knowledge the background and skill sets of all the people who have posted here with criticisms, and also implies that you are the professional in this subject. Your remark to Black Dog asking whether he could read CAD files...came off as somewhat flippant...I would bet that there are TOD members who can indeed read and analyze AutoCAD, Pro/E, SolidWorks, etc.
I will reserve judgement...perhaps you will prove to be the right man to lead a team of designers, builders, financiers, politicians, and construction personnel to advocate, design, and implement the construction and operations and maintenance of this idea.
However, the lack of sufficient engineering and programmatic details presented here do not yet provide confidence in the feasibility of this idea.
The comment was directed to "some pretty vitriolic", and my point was that I have been attacked by professionals, members and employees of a cult I should not name. If you look here, http://en.wikipedia.org/wiki/Keith_Henson you can probably figure it out. This also might amuse you http://www.kuro5hin.org/story/2006/4/21/171516/867
I was actually fishing for someone who could help.
Not a chance. I could lead a team of 25, having run a company of that size. But this thing would involve thousands, more likely tens of thousands, of engineers.
The *only* topic considered in depth in this article was combining two high exhaust velocity transport methods to get a substantial fraction of the takeoff mass to GEO and the cost down to $100/kg to GEO so the cost of power satellites makes economic sense.
Most of the comment has been directed at things that were just mentioned in passing or as background.
Keith,
Thank you for taking the time and effort to respond and help clarify.
Best of luck, and once again, thank you (and Gail) for providing this post and provoking interesting discussion.
Well I thought I was done, but "space armada vs. coal" is an impressive strawman.
And if those pointing out the infeasibility are amateurs, I may as well uphold the honor of amateurs by adding a little.
I already pointed out that 'effectively impossible' projects like this are magnets for scarce funding to actually solve the very real problems our world faces, and I have seen it happen, since "oldfarmermac's razor" is not widely practiced by the investor or granting community either. Expertise and appeals to authority, at this point in this culture, are primarily reductionist and thus probability-blind in a systems sense.
Since my teenage years, I've been a big fan of big zoomy things, scifi and masturbation, so I'm not down on the post per se. Nor do I condemn any religions which depart from reality - as they generally must - to give their adherents comfort, even crypto-religions with the trappings of engineering verisimilitude. I just think one needs to file that stuff separately in one's mind from, y'know, actual plans.
Payback time of two months? Woof? Starting from when and paid back when? We seem to be ignoring some rather conspicuous thresholds here.
But rather than pick nits, I'll just add a scifi quote that springs to mind as relevant. It's the concept of "crazy eddie" from "Mote in God's Eye", a particular sort of insanity brought about in reductionist minds by impending civilizational collapse.
"it was difficult to work with creatures who might suddenly see an unreal universe and make judgements based on it. The pattern was always the same. First they wished for the impossible. Then they worked toward it, still knowing it to be impossible. Finally they acted as if the impossible could be achieved, and let that unreality influence every act."
But in the end the cycles did end and Crazy Eddie had his victory.
Indeed. A scifi victory, a fine and enviable madness suitable for publication, in which exponential growth continues via wormhole and colonization. I was going for the archetype, not the wormy plot device.
Deus ex machina endings are great for literature, less so for planning purposes.
It's detailed in the text. Straightforward analysis. If you have any problems with it, tell me where you have the problem. Like rooftop solar cells, you only count the energy needed to make and transport (install) them, and in the case of power satellites, the energy to make them is small.
You don't count the energy used for making the Skylons because they get used at least 500 times. But you do count the fuel they burn. Same as counting the fuel a truck burns but not the energy cost of making the truck because it is (presumed) to be spread over a very large number of installations.
People do things like the Moties. They go irrational when faced with a bleak future because in the stone age it was in the interest of their genes to do irrational things like attacking neighbors.
Let's see. You have made no objections to my number of 254 kWh/kg
Round numbers 250 kWh/kg and 100 kg per person would be 25,000 kWh per person. Given that the average energy use per person in the US is around 10 kW, that would put them using 80,000 kWh per year. Considered as an energy payback problem, less than 4 months before the energy used by a person would equal that needed to get them off the earth.
Not bad.
Yes, I have read Fecundity Unlimited. I am unaware of any Asimov book that I have not read.
The answer is blindingly obvious. We cannot have as many babies as we want. Breeding will have to be regulated. No Nobel prize for that idea.
However that is no excuse for procrastination.
We have to go off-planet.
I anticipate that the endeavour will cost us millions of lives. Not going is going to cost us Billions.
This planet can only support 1.1billion without Oil. (assuming pristine soil and water).
Blanket assertions that it cannot be done reminds me of the blanket assertions made by the "experts" that heavier than air flight was impossible. Even after the Wrights succeeded they were ignored.
Such is the folly of the human Ego.
....sigh.....
look. I love space exploration & stuff. Grew up on Heinlein books, built model rockets, met von Braun, later met with O'Neill and helped push for his visions, worked with astronauts on various projects, joined the board of a space exploration NGO giving awards to space-based exploration and engineering projects to help the earth. Last time I went to the mainland, I stayed at NASA Ames. Heck, one of my larger tech/demo projects was personally funded by Arthur Clarke, and before his death I spent time in conversation with Dr. Bussard to see whether I could arrange for a much-larger demo of the polywell technique, on the off chance it might be interesting. My point is, I'm no Luddite.
And I enjoy good scifi still, which is why I enjoyed this post.
But.
There is a huge disconnect between "engineering concepts" and built reality. The first filter one must always look at is "is this project physically even possible?" And indeed, the physical universe wouldn't preclude something like this, if done competently, just as it might not preclude something like a dyson sphere built by dolphins.
However, there is a huge difference between "the set of things that are not physically impossible" and "the set of things the human race as it currently exists can do".
Many things come into play: a mechanism for diverting a huge amount of money to a chancy program with a long-term payback IF it works perfectly. The odds that no one will take some sort of political umbrage at what are conceptually tantamount to giant orbiting death-ray stations. The odds that nobody will sabotage them if they did get deployed. The odds of reducing lifting costs by a huge factor. The odds of ALL of the necessary breakthroughs happening in the nick of time as societies start to retrench and collapse from a permanent drop in petroleum energy. Etc Etc Etc.
So projects like this one, and many others which might make a good Popular Science 1950's magazine cover, don't pass the second basic filter. That filter is the aggregate probability of success. If it isn't obvious, it goes something like the so-called Drake equation. Just take the odds of each requisite element happening, and multiply them, and you have the odds of the project happening.
So the odds of driving down launch costs to orbit by a factor of 200 in the next few years, times the odds of scaling that up hugely, times the odds of getting hundreds of billions of dollars invested at a time when NASA can't even afford to keep its existing satellites happening, times the odds of inevitable crashes not affecting the funding, times the odds of "space death rays" not being banned by a vociferous public campaign, times the odds of developing a reliable way of assembling kilometer-sized structures in orbit and stabilizing their orbits against solar wind, times....
....which means that for a project like this, the real-world odds of it being done by the human race; the corporations, cultures and nations - the existing evolved systems - rapidly fall towards one in a trillion and far lower. Like winning a fair national lottery dozens of times in a row... AND having that be your main plan.
So again: first filter, is it physically possible. Second filter, does aggregate probability make it impossible in principle. No need to get to subsequent filters on this one.
A shame, but there it is. This concept is entertainment and should be appreciated as scifi. Nothing wrong with that. But it won't happen, and the venture capital it skims off (and I know of some which has been) will take us that much farther from stuff that might have a chance in the context of our evolving systems.
Bravo, a well argued dismissal. I like your 'dyson sphere built by dolphins' - instructed by Mark [Patrick Duffy]?
It must be highly frustrating for any well-educated engineer that schemes as grand as these seem within reach, technically, but will never substantiate by the closing window of opportunity on cheap energy and the financial and social upheavals this will cause.
It's for the better, I suppose. The future trend, as I see it, will be to small, smaller, very small, distributed energy generation on a human scale. The less money and energy we waste on grand schemes, now, the less waste we will leave behind for our children to live with.
For the US and possibly the western world I think you are right. I don't even try and as a matter of fact, might risk jail (ITAR) if I get down to detail work on it. But the Chinese could certainly afford it and the Japanese have a desperate need for an energy source.
I suspect that the energy poor children of the next generation who are beholden to the Chinese for their synthetic gasoline will revile your existence.
hi Greenish,
I just knew you would beat me to the punch;you probably remember when we had this more or less same discussion a year or more ago in respect to putting a large number of satellites into orbit.
I believe I beat you to it that time,iirc.
To add a bit of extra perspective:
We are used to seeing order of magnitude improvements all around us in various technologies.When i was a kid, transistor radios wewre huge and hugely expensive and would barely work within sight of the station, now a radio combined with a music library and high fidelity sound system will fit in your ear and costs only peanuts.
But this improvement came about INCREMENTALLY and each an d every incremental advance in the thousands of different steps involved paid its own way in the world of dollars and cents.
A space based power system simply won't get built within the forseeable future because the up front development problems and costs are unmanageable.
If bau were to continue "as usual" for another century or so(an impossibility) most of the problems would probably be solved while in pursuit of other goals, and then such a system might be feasible, as the larger part of it could be built with off the shelf , previously commercialized technology.
You did indeed. Perhaps the logical principle should be formalized as "oldfarmermac's razor" to give you the same level of attributory credit Occam enjoys.
Blindness to the limitations of aggregate probability is perhaps the most common fallacy among techy-engineer types proposing world-fixes. I've been long aware and leery of it, but had never seen it as succinctly elucidated as by you, so like all good formulations I've glommed onto it. Your 10 cent royalty payment will be in the mail.
Seriously, you should popularize it, and from here on I'll call it that in such discussions.
cheers
Rapid progress is seen only in one field: solid state electrical engineering, which is driven by progress in material science. In any field related to mechanical engineering the progress are minimal and driven essentially by progress in material. Agriculture dont growth exponentially either.
..with the possible exception of mechanical engineering feats which owe their existence not to 'advancement', as one might propose, but simply our ability to throw just gargantuan volumes of dispatchable FF energy at it, such as the massive earth-moving machines that are central to Coal and Tar Sands extraction. They might seem like technological growth, but are really functions of cheap and surplus energy availability.
Motto of the Industrial Revolution (according to William McDonough)
"If brute force doesn't work, you have to use more."
Somehow I can't get the words "cargo cult" out of my head... Sorry, not intended to be mocking, just the feeling that I'm listening to an impassioned sermon from a church I no longer belong to :-)
I'm always alert to any scheme that takes more farmland out of production, and it sure sounds like this is a guaranteed result of the groundside array siting. If nothing else, military and govt will insist that such facilities are essential to "national security" and must be fenced off, no? But I would also not be too sanguine about the effect on crops and livestock -- it might take a few decades for negative results to be (a) noticed (b) reported (c) denied (d) obfuscated (e) spun (f) buried (g) revived after overwhelming evidence became too inconvenient (h) finally admitted but regretted as inevitable and "the price of progress." Meanwhile, diminished food producing capacity.
IMHO food is becoming our most urgent issue, and we can't eat electrons. If "unlimited" energy enables BAU to continue then billions die anyway because we're undermining our own food supply (by ubiquitous toxicity, soil abuse, liquidation of species diversity etc). So forgive this old cynical ex-Trekkie, but "10x more energy really cheap" plus "huge ultra-complex high-tech project" plus "we'll need to occupy large swathes of farmland" for me adds up to "Uh-oh."
I suspect that engineers (an honourable guild of which I'm a card-carrying member) don't like problems that can't be solved by engineering. I suspect that our current problems are not just another nail, and the same old hammers are not going to work; but hammers are what we know and love, so we keep trying to make the problem nail-shaped. Our intentions are good, but... This sounds to me like a wondrous new improved steam-powered hammer... a delight to contemplate and would make a grand Chesley Bonestell painting, but it's still a hammer and we're facing, not a nail, but a Gordian knot.
OK I just ran out of metaphors and have real work to do involving human-power.
I no longer believe in Star Trek, sadly, in the same way I no longer believe in Santa Claus or the Tooth Fairy. Maybe the Technofaith will pull a technorabbit out of the terrestrial hat and reconvert me late in life, but I think the odds are low. Mostly I find myself agreeing with ol' Eric that "The chief cause of problems, is solutions." Esp solutions to the wrong problem.
Transitioning to SSP would greatly increase our available farmland.
Why? Because the downlink sites (rectennas) would be essentially electronic chickenwire, suspended ~twenty feet in the air, so cattle could graze or crops grown under it. It essentially uses no land and no water in operation.
Transitioning to SSP would greatly increase our available farmland.
Right - because farmland has nothing to do with the quality of the soil, the influx rate of photons, the temperature and water.
Farmland is *ALL* About:
Chickenwire suspended over some land.
By God, once you put Chickenwire over Land it's not BAM! farmland!
I'm not so sure about that. Archaea can use electrons to reduce carbon dioxide to methane (at 80% efficiency!), and there are methanotrophic bugs which eat it and produce sugars, fats and proteins (add a shot of electrolytic NH3 if needed). A couple trophic levels up and you've got something like anchovies or shrimp.
If you can make the power-to-calories system even 5% efficient, the 340 W/m² power beam becomes 17 W/m² of food. That's about 300 Calories (kcal) per day from a square meter.
A good corn crop is perhaps 200 bu/ac (~500 bu/ha). A bushel of corn is about 392,000 BTU, or 99,000 kcal. This is 4,950 kcal/m²/yr or 13.6 kcal/m²/day. Electrons to food looks a lot better.
"Power satellites are an idea that has been around since the late 1960s [1] but not developed commercially because we don't know how to build an inexpensive space transport system......"
And if we DID know how to build an inexpensive space transport system? Why litter the earth's orbit with satellites when they can be deployed to orbit the sun itself and use its intense solar energy to convert dissipated matter into an energy dense storage medium? Then humans would have unlimited energy in as high a concentration as fits their hearts desire. Then what? The population would explode until it is twice, three times, four times what it is now. Then what? All nature would be obliterated and the surface of the earth would be carpeted with an endless expanse of urban sprawl, until the earth resembled the Death Star from Star Wars.
Technological fixes must be abandoned until humans unlearn the habit of using them to create more problems.
Even if such advanced technology is within the reach of theory and practice, it is much better to condemn humankind to death by starvation, war and disease than to give it further license to continue with its rapacious growth. As things stand, we live in an adolescent culture. Why equip adolescent minds with further means to do damage? It is a hundred times better if, through hardship, this middling race graduates into a higher consciousness. All of its wealth and power came to it prematurely, before it learned to distinguish between things of transient value, like iPods, condos and Porsche's, and things of everlasting value, like Biodiversity and the human cultural heritage. It creates the former in superabundance, and is destroying the latter with no remorse, just like an adolescent would.
Energy allows us to colonize off planet. To no put all our eggs in one basket. To ensure the survival of the species. A good thing from my POV.
Who cares? Wake me up when every sunny-climate roof has photovoltaics and power plants are using mirror arrays to boil something.
OTOH, Nasa and the military/aerospace industrial complex probably smell another taxpayer scam, so I'm sure this turkey will get off the ground long before it makes sense.
In the meantime, everyone can conveniently forget the pressing issue is liquid fuels, not electricity.
It's one of the reason I set the cost goal so low.
Penny a kWh will make $30/bbl synthetic oil
Two cents will make $50/bbl.
There are already plants up in the billion dollar range that run on reformed natural gas but could use hydrogen from water and CO2 from the air to make gasoline.
At $8 an installed watt you are going to have a nice looooong nap.
Where do you get that? The article clearly states that the cost can't exceed $1,600 per kW or $1.60 per watt.
The closer we get and the faster we run towards the edge of the fossil energy chasm, the more vigorously we flap our arms and proclaim that we can fly.
Humans love stories, images, fantasy, magic and mythology.
We've all seen Wile E. Coyote chasing the Roadrunner over the precipice and hanging sheepishly in mid-air just before he plummets straight down and limps off to the next episode. We're amused, but we know that things don't really work out that way. It's only a figment of someone's imagination.
That cartoon image is no more or less a work of fiction than the idea of this orbiting solar collector or the myth of nuclear energy that's too cheap to meter.
In reality, the effect of gravity would be immediate and the coyote's fall to the desert floor would be fatal, just as the complex orbiting microwave system would be unmanageable and dangerous radioactivity and environmental damage would eventually trump the benefits of nuclear fission.
We need to back away from the cliff. Failing that, we must at least clamber carefully over the brink in the hope that we can survive the slide down.
Building Skylons, flying to GEO, massive structures, massive microwave transmitters, hugemongous laser driver arrays, massive receiver arrays, making vast quantities of hydrogen fuel, maintenance, replacements, huge grids to support the deep desert receivers, replacing pranged Skylons, reserve power for when the array tracking goes AWOL....
err what was the EROEI again?
NAOM
As recent DOD study said 1 year to pay back invested energy. So with a 20 year life time EROEI is 20.
Wind turbine do much bette.
I get an energy payback in 2 months. If that's right, then the EROEI for 20 years would be 120. If they last 50 years (why not?) the EROEI would be 300.
This is hard to believed. Ground based PV do 10 on the best sites. Space might provide you with better Sun but acces is expensive.
Skylon alternative?
A home-made rocket built by two Danes successfully blasted off from a floating launch pad off the Danish Baltic island of Bornholm Friday...
The nine-metre (30-foot), 1.6-tonne rocket and its small capsule have taken space enthusiast Madsen, former NASA employee Kristian von Bengtsson and an army of volunteers some three years to test and build.
Last year the group, which is financed by around 20 companies and 2,000 individuals, said they had spent a total of 50,000 euros ($73,000) on the prototype.
http://www.google.com/hostednews/afp/article/ALeqM5iMonN3M3klp1ZhoxhT-B9...
For a good comparison of the 1977 study versus the 2007 study see
Space‐Based Solar Power
As an Opportunity
for
Strategic Security
Phase 0 Architecture Feasibility Study
Report to the Director, National Security Space Office
Interim Assessment
Release 0.1
10 October 2007
A DOD study.
To an order of magnitude the transmit antenna is 3km and the receive antenna is 3km. You can make one bigger by a factor x and one smaller by a factor x. For example 1.5km tx and 6km rx. This is what sets the scale for the orbital leg of this system. The smart idea that Solaren had was you do not need to use one continuous tx antenna you can use several separate tx antenna just like radio astronomy on Earth uses an array of separate dishes. They will fly a constellation of PV+tx satellites. I do not know what separation they will use but if they can get a factor of 10 we can go to a 0.15km or 150m tx phased array. With a constellation of 4 this is a savings of a factor of 25 in tx array size/mass. This allow a constellation net electric of 200MW as planned.
"The smart idea that Solaren had was you do not need to use one continuous tx antenna you can use several separate tx antenna just like radio astronomy on Earth uses an array of separate dishes."
Maybe, but I'm not so sure, and I don't have the necessary simulation tools to check. Normally, with a sparse array, you get side lobes, and the sparser the array, the more ends up in the side lobes. The astronomers, if they're careful, can work around that by setting things up so the side lobes 'look at' quiet spots in the sky, which is most of it. And they can get by with reduced amplitude, which is just proportional to the actual area, as long as they get focus in the main lobe. Ditto for radars, dither the right way and smear the side lobes all across the sky if you want. But this thing can't take that shortcut. It needs the full amplitude - can't just throw the energy into off-target side lobes. So have they or anyone else got anything about that? (Obviously not on their blank web site.)
You say 'a DoD Study' as if the fact that DoD studied something is some kind of guarantee of success!
I am very familiar with the DoD...there are many thousands of studies which have been done about this, that, and thousands of other things, and many of the topics studied/advocated for/warned against have come to naught.
Sure, many DoD studies hit the nail on the head, and some even lead to action, and some of those actions even have positive consequences.
However, many studies sit in repositories and amount to nothing.
Edit: Writing studies, however, can be a profitable pastime!
I am just telling you DOD so you can place the study in its social context (i.e. know who paid for it).
Actually, DOD paid almost nothing for the study. It was four officers who got a lot of volunteer help over the internet. I think they "published" it on the net so they didn't even spend money on paper.
This whole article seems to concentrate on the details and ignore the main Problem: http://en.wikipedia.org/wiki/Wireless_energy_transfer#Timeline_of_wirele...
Wireless Power state of the art today is flying toy helicopters, and powering a TV at 20 inches.
Rectennas receiving significant power from 23,000 miles away is right there with warp drive and transporters.
From the Wikipedia page you point to:
# 1975: Goldstone Deep Space Communications Complex does experiments in the tens of kilowatts.[33][34][35]
"Between 1969 and 1975 Brown was technical director of a JPL-Raytheon program that beamed 30 kilowatts over a distance of 1-mile (1.6 km) at 84% efficiency."
I presume you are not a microwave engineer. I doubt you could find one in ten thousand of them who would have any doubt about microwave transmission from GEO working. It's based on optics principles that are over 200 years old.
There are problems with space based solar power, but getting the energy down by microwaves is not one of them.
Keith, keep up the good work. I am glad it is you taking the heat rather than me ;)
The case for may be settled in 2016.
The case against may never be settled.
Then of course there is falcon super heavy ;)
30 kilowatts 1 mile is impressive, what is the record of a test project in the intervening 35 years? How much consumables (cyrogenics) were used?. If microwave power transfer really is so easy, you would think there would be 1000's of applications in use today. Milliwatt level RFID is all I am seeing.
BTW, No I'm not a Microwave engineer, I'm a Telco engineer.
There were other tests around that time, helicopters and such. But it was one of those thing that just didn't find a use at the time.
There were no cryogenics used that I know about. I can't think of what they might even be used for.
I used to drive by the rectenna array set up on a hilltop at the Hughes facility on Jefferson Blvd in Los Angeles everyday. I believe there were loads, spotlights, interspersed for the demonstration of transmitted microwave power.
http://en.wikipedia.org/wiki/Thinned-array_curse
That 84% is the efficiency at which the rectenna converts the microwaves presented to it to DC. It doesn't include losses at the transmitter, or transmission losses(Rayleigh criterion).
PDF warning: http://www.leonardo-energy.org/webfm_send/2837
This 2009 briefing goes on to say:
It doesn't say whether that's 3KW input or transmitter output or the distance.
It also talks about failed attempts beaming power to remote Alaska and Hawaiian villages.
Sorry to keep harping on the Wireless Power Transmission problem, but to Me, the inability to make it work "point to point" on earth makes Space based power a nonstarter.
As someone else has already stated there are much better uses of limited research money.
I just hope some unwary politician or investor stumbles across this showstopper before it's too late.
The overall chain of loses is right at 50%
Which means that if you want to charge 2 cents on the earth, it can't cost more than one cent going into the transmitters.
That's because we have options, wires and taking the fuel to the villages.
Skylon is a UK project. Microwave power transmission is well understood by microwave engineers.
It's up front, always has been clear back to the 70s.
At what distance? Reference please.
From my link above:Grand Bassin project-"700 meters and delivering 10kW with an overall efficiency of 57%." Hawaii demonstration-20 watts over 148KM...possibly up to 64% efficiency.
Wires and fuel were poor options for Alaska and Grand Bassin, that's why they considered wireless power transfer.
GEO to earth surface
Page 20 here: http://nss.org/settlement/ssp/library/1981NRC-ElectricPowerFromOrbit-1.R...
Though there are references that go into more detail about the loss chain.
For rough engineering, loss of 1/2 is good enough.
This document makes very interesting reading, thanks for the link. I think everyone commenting here needs to read it fully! Note all the cautions. See the estimates of resources needed.
Mention of 100,000 30-50kw klystrons per antenna with several thousand needing replacement or repair per year.
Mention of large number of persons in GEO to perform constant maintenance.
Problems with shielding said persons from solar storms, etc.
Mention of potentially harmful interference to communication satellites.
Major changes needed in spacing, number and design of non-SPS satellites to accommodate the SPS satellites.
Major problems predicted with sharing geo-sync orbit with other satellites.
This does NOT give the rosy view of this system that's being presented here on TOD. It's also amazing to use a document from that long ago to produce cost estimates! Especially when it admits that they really can't be made.
As greenish said here http://www.theoildrum.com/node/7898#comment-810014
Perhaps that is why everybody and their monkey is working on it?
Asking that question shows that you don't have a good grasp of the issues.
Let's start with distance. Distance is only marginally relevant. The beamwidth of a circular uniform planar radiator is 1.22λ/D, where λ is the wavelength, D is the diameter and the result is in radians. This can be made arbitrarily small by increasing the diameter of the transmitter.
The real factor is how much air the beam has to go through, and a bit about the ionosphere. From the top of the atmosphere to sea level goes through about the same amount of air as 3 horizontal miles at sea level.
Details like optimal power density at the rectenna and safety margins outside the collector are fun exercises for the engineering student. The default uniform circular radiator has a far-field beam which falls smoothly in power density from the center peak to a null, rises again to a lower peak, hits a null, etc.; its beam profile looks like the frequency profile of the Butterworth filter here. A more sophisticated transmitter antenna can achieve a profile that's flatter in the main beam, lower in the sidelobes with a sharper cutoff. It looks like the elliptic filter profile in the same image. (If you're wondering why the beam-profile of an antenna has anything to do with the frequency response of a filter, it's because they are described by the same equations.)
There are no real mysteries in this stuff. It's all basic physics and optics, just arcane as all hell because we've never used it this way before. Should it become commonplace, it'll become as mundane as fuel-injection systems.
Bingo
I wonder how small a percentage understand them?
E-P, You could be right. I am just trying to put things together. Like this from my previous link.
Then you say "Distance is only marginally relevant."
I realize microwave beams can be tightly focused, but 23,000 miles is no walk in the park.
E-P, would you happen to know why the mentioned WPT projects "Grand Bassin - La Reunion" was stopped, or have any additional information on the "Alaska '21", or any other similar Wireless Power Transfer project?
θ = 1.22λ/D
When θL >> D, the diameter of the beam is proportional to distance (that's a given). You're also failing to grasp that this has been completely incorporated into the system calculations already. Another thing you fail to grasp is that if the transmitting antenna is big enough or the wavelength small enough, 23000 miles may still be less than θL. But that does not apply to this particular case of SSPS.
"The beamwidth of a circular uniform planar radiator is 1.22λ/D, where λ is the wavelength, D is the diameter and the result is in radians. This can be made arbitrarily small by increasing the diameter of the transmitter."
True, the calculations are very simple, I guess you're one of those that find it trivial to put theory into practice, in space no less. Let's see, multiple mile square transmitting antenna array, beamwidth on the order of 0.001-0.002 degrees at 2.54 GHz. Just to maintain a 1/10λ peak/valley surface you're going to need 1.25 cm or better positioning accuracy and stability over the entire array surface. And that won't be near good enough for the beamwidth you're requiring. Yes, you could compensate with phase changes at each transmitter for initial irregularities, but you then have to continuously measure and compensate for drifts over the entire array.
"Asking that question shows that you don't have a good grasp of the issues."
I shouldn't even bother responding any more to things on this subject as it'll never even be attempted, but this statement is just so far out there. Someone else doesn't have a good grasp of the engineering/manufacturing issues involved.
Phased arrays always have phase shifters. That is probably why they are called phased arrays. Rat-race switches and squiggled delay traces make digital ones.
http://en.wikipedia.org/wiki/Rat-race_coupler
http://www.microwaves101.com/encyclopedia/phaseshifters.cfm
Beam-forming and phase conjugation to hold a beam on target are just part of the deal.
This is not where the problem is.
I'm quite aware of the details of the phased array. Seems that so many of the supporters of this concept aren't able to back off and look at a larger picture, just at their own little one. This phased array is not only many orders of magnitude larger than anything we have ever built, it's in space, free floating and not on a rigid platform. This means that each of the millions of transmitters will have to have it's position measured and adjusted continuously. And every other system of this monstrosity has similar never-done-before problems.
Please refer to the post that oldfarmermac just made. He understands what I'm talking about.
http://www.theoildrum.com/node/7898#comment-811157
I should guess it is not millions of antennas.
It is perhaps not a phased array.
It could be whacking-great klystrons and high-gain antennas.
The separate beams need to be uncorrelated, anyway.
They were punching holes through tanks at a distance decades ago.
This is not the problem.
The lifting is the problem.
Humans can't bend space.
I assume you mean with high-power microwave beams. I also assume your reference to 'tanks' was of the variety such as the M-1, T-60, Merkava, Challenger, Leopard I, II, etc.
I cannot say this in any more of a straightforward manner: Poppycock! Incorrect!
Please do not make stuff up.
I can not find any references online.
These were not platform-mounted.
No, they were not spectacular demos.
About like this:
http://www.youtube.com/watch?v=XyTRhw8qmHE
But I remember those times well.
Are you speaking from personal knowledge gained from first-hand observation or participation?
Are or were you a government/military researcher?
I was in the business, yes.
This is a video of a USN/ONR ship-mounted high-power LASER.
This technology has been widely known to people without any type of security clearances for at least a decade.
Your original comment was referencing microwave beams, not IR, visible light, UV, etc. LASERs.
You also said 'burning through tanks' (such as the tracked vehicles with guns and heavy armor)...not through thin-walled outboard motors.
HPM are potentially good for crowd control at short distances (up to several hundred meters), and for upsetting or burning our electronics from short-to-medium (perhaps a few miles, maybe) distances...not for burning through several inches of steel alloy/ceramic laminate armor.
Area denial is a relativly low-power system.
Electronics can be taken out with capacitors, spark-gaps, and horns.
The demo is slow, and fun!, so enjoy! From about April.
___________________
The problem is getting the material into space.
The lift.
There's nothing magical about doing things in space. It's far more difficult to work with extreme beam intensities, like the laser-fusion folks.
Well, yes, you do. That's how the system is supposed to work; a pilot beam from the receiver provides the phase reference for the transmitter. Structural distortions and such are automatically adjusted out of the transmitted power beam. Mostly this requires an accurate time reference for each segment of the transmitter, and that's a solved problem (VLBI work is much more exacting).
What we'd probably want to do is to allow for smaller rectennas of lower power rating, say 1 GW instead of 5 GW. This would require each transmitter to create 5 separate beams, each one narrower to cover a smaller rectenna. A transmitter array covering a 3-4 km circle ought to do the job. Pumping 5 GW out of a 3 km circle only requires 700 W/m² out of the antenna; this is roughly 1 microwave oven per square yard.
That Wiki page is confusing because it conflates a number of different ways of transmitting power wirelessly into one apparently-linear time-line. (Insert apples-and-oranges lecture from X here.) The transmission method most in the general news lately has been what the page calls "inductive" or "resonant inductive", which, unlike microwaves, doesn't focus at long distances. The issues at hand here aren't as much with theoretical technical feasibility as they are with practical logistics (such as keeping a large crew indefinitely at geosynchronous orbit when the world seems to have nearly run out of steam keeping a small crew at the ISS in low orbit.)
In the context of a parts flow that will ramp up to 60 t/h and a transfer time of about 6 hours, I think it will be less trouble to keep a large crew at GEO than a small one at the ISS. For one thing, the habitat will be spinning.
Hi Keith, I posted this earlier, you probably didn't see it:
Are you aware of this possible alternative to GEO? You still get 24 hour sunlight and it's a much lower orbit.
http://www.earthspaceagency.org/space-articles/space-opinions/the-space-...
The DOD study says it would cost 9 billion dollars to put up a plot plant. We spent 20 trillion dollars on transaction guarantees that Noble Prize winner Stiglitz says we will be lucky to see 4 trillion repaid (16 trillion net cost) to keep the white shoe boys rich. So 20.0 versus 0.009 for either nothing or a domestic carbon free sustainable energy source. I think the first is a waste of money and the second is worthwhile.
I see this as nothing more than a thought exercise, but I would think that there would be easier/cheaper ways to accomplish this task.
The first thing that comes to mind, is that if one wants to launch a lot of tonnage, the easiest/cheapest way to do it would be from a smaller gravity well - such as on the moon.
Laser propulsion would still work on the moon, being fueled by solar power. The moons rotational speed of 28 days would also simplify this process.
If the materials needed to build such a collection system where cheap and common, would they not be available on the moon?
The largest expense and most difficult task would then become placing the manufacturing center on the moon, and we KNOW we can go there.
So - send equipment to the moon and build a solar collection array. Using solar power and equipment from Earth, build the refinery needed for raw materials. Once the refinery is complete, build the manufacturing base need for the solar collection system using local raw materials and power. Build solar collection array, beaming equipment, and launch vehicles, and send to GEO.
Lastly, bilk rate payers for $$$!
You are right. The question is how much mass needs to be brought to the moon to reproduce modern technological manufacturing? And how much time does it need to double its capacity? How many doublings are needed to get to a level to produce SPSs? How much will this cost?
It is a good solution. I like it. We need to prototype it here on Earth.
Keith,
I'm curious what you think of this concept for powering aviation?
It's not a new idea*, but I think it's fair to say that we simply really haven't needed an alternative to jet fuel up till now, and like all large industries aviation is very, very conservative about innovation that makes everything obsolete. But it would appear to be entirely viable 50 years from now when liquid fuels start to be truly scarce.
What do you think?
*"microwave-powered airplane" - dozens of hits. http://www.friendsofcrc.ca/Projects/SHARP/sharp.html was #1 but #2 was a Time article from 1964.
--
http://www.nytimes.com/1987/07/21/science/new-kind-of-aircraft-is-on-hor...
Nick, Flight is high on the list of reasons to develop wireless energy transfer.
http://www.defensenews.com/story.php?i=5043125&c=FEA&s=TEC
Zero fuel drones are very close to reality. LASER not microwave.
Oh, dear. The FAA is going ape over 50mW laser pointers, and we're going to point hundred- or thousand-watt lasers into the sky to power drones?
hhhmmm.
Lasers vs microwaves - which is better, and why?
Rectennas are cheaper than PV, right?
For the launch:
Lasers heat the propellent which exits at high velocity.
For the ground-station:
Rectennas are able to achieve high efficiency.
Here is one at 80%:
http://www.ece.umd.edu/~dilli/research/smartdust/power/antenna_rectifier...
The launch vehicle absorbs the laser energy to heat the hydrogen propellant through a heat exchanger, there are no PV involved. With aircraft a similarly simple system has been proposed in which the heat exchanger replaces the combustion chamber in a jet engine.
Back in the mid 70s at the Space Manufacturing conferences there were several presentations about powering aircraft from above with a laser that would not go through the atmosphere very far. So the planes would have to climb to 35,000 feet before they switched to being laser powered.
My thought is that if you have a really large space presence it is probably less trouble to bring the energy down as microwaves and make synthetic jet fuel.
There is a related business of powering rockets or rocket planes with microwaves. It's a possible alternative to the Skylon for a first stage.
http://www.foxnews.com/scitech/2011/01/25/nasa-exploring-lasers-beams-za...
hhm...
let's take off our space/satellite hats, and put on our aviation hats.
Let's assume for a moment we simply power planes from below, using ground based transmitters and $.06/kWh power. I wonder what the economics would be?
We could put PV on the top of planes, and rectennas on the bottom.
What do you think?
Compared to the advantages of an airliner with much greater useful load and effectively unlimited range? I suspect the opposite, and the several-fold cheaper energy delivered to the aircraft clinches it. It's the same thing Dr. Ulf Bossel said about hydrogen fuel cells: if the hydrogen is made from electricity, it can't compete with its own energy supply passed through batteries.
Also, the beamed-power aircraft doesn't have to slow down for the sake of economy over longer legs. Passengers will pay more for a faster trip.
an airliner with much greater useful load
I suspect that would be balanced by the need for batteries for 1) power surges on takeoff and landing, and 2) backup for safety's sake.
effectively unlimited range...doesn't have to slow down for the sake of economy over longer legs. Passengers will pay more for a faster trip.
That's a big deal: no need for refueling, much less need to worry about running out of fuel while circling the airport.
the several-fold cheaper energy delivered to the aircraft clinches it. It's the same thing Dr. Ulf Bossel said about hydrogen fuel cells: if the hydrogen is made from electricity, it can't compete with its own energy supply passed through batteries.
That's a big deal: both the solar power from above and the grid power from below would be low cost, perhaps $.10 per kWh. That's the equivalent of $1 jet fuel.
Jet fuel is about 40 kWh/gallon. So a gallon would be $4.00/conversion efficiency of perhaps 75% so $5.30 a gallon plus a capital charge of 25 cents. (plus taxes etc)
It could be done, but a lot fewer people will be flying.
You're thinking of conversion to synthetic jet fuel, right?
How did you come up with a capital charge of 25 cents per gallon?
Yes.
Based on what the Sasol plant in Qatar cost, $1 B, 34,000 bbl/day x 365 is ~10 M bbl $1 B/10 M is $100 per bbl of capacity.
Written off over 10 years, $10/bbl. $10/40 gal/bbl is 25 cents a gallon.
The CO2 extraction plant might increase it some, but surely not a factor of two.
What kind of CO2 extraction are you considering?
Remember, we're thinking of a world where the coal plants are all shut down, so we have to extract the CO2 from the atmosphere or the ocean, right?
Has anyone seen any cost estimates for that?
http://www.ucalgary.ca/news/september2008/keith-carboncapture
It seems there are several ways to get CO2 out of the air and none are very expensive.
It takes so little energy (2%) by comparison with making hydrogen that you can ignore it.
Capital equipment is big, but dirt simple.
That's in the long run long run where you have more energy than you know what to do with. Early stages you might use the coal we are mining and make it into syngas by heating it in steam. That gets part of the hydrogen as well as the CO you need for Fischer–Tropsch Synthesis.
The current mining rate of coal will make enough synthetic oil for the US to become an oil exporter (if they did it). But, of course, you have to shut down the coal fired electric plants to free up the coal. (And rebuild the plants as sinks of electric power that make synthetic oil.)
Don't use batteries. Use synthetic kerosene or liquid methane. They're far lighter and ought to be fully compatible with a laser-heated gas turbine system. That's also the backup.
Another possibility is to beam power from the ground for the takeoff and climb.
Don't use batteries.
Of course - we'd want to use an extended range EV model, with a relatively small battery, beamed power and liquid fuel for backup.
synthetic kerosene or liquid methane
Which would we prefer, do you think?
laser-heated gas turbine system
So you're thinking of a ground laser? Somehow that feels more sensible with a rocket, where all the activity happens around the launch site. Aviation routes would need a lot of infrastructure, and microwave transmitters would need less precision.
Somehow the idea of thousands of 50MW lasers following planes on a daily basis with millimeter precision makes me uneasy. It would certainly make for one heck of a weapons system.
Makes one wonder why the military are so interested in these schemes;)
NAOM
Jez - are such ideas still TOD worthy?
We needed a break from go-back-to-the-19th-century gloom and doom.
How much in total will it cost to get to the stage of the first 60t/hr flights, including all R&D and infrastructure costs, astronaut training etc?
How many years would it take to get to the first take-off point?
Do the costings assume current prices or allow for increased competition for resources?
How many new launch pads would be needed? Has this been included in costings?
Cost?
I have not put the numbers for this version through a business model. The previous time I did it it came in about $60 B, but this is much less expensive. $40 B perhaps. There may be even less expensive approaches.
Years?
Less then ten.
Prices?
If you built them using PV, it would use up a lot of production capacity.
Launch pads?
No launch pads, the Skylons take off from specially hardened runways on or near the equator with a lot of water to the east. Been included.
Keith,
I am curious..what does your cost estimate of $40-60 Billion U.S. Dollars and schedule estimate of ~ 10 years buy? Meaning, how much installed capability on-orbit, expressed in number of power sats, number of human habitats, number of on-orbit parts and station-keeping thrust fuel depots, and amount of electricity generated and transmitted through the antennas. Also, how many rectennas on the Earth, and how much power will rectified and provided to the terrestrial grids? Has your team determined possible locations for the rectennas?
Is this the cost for just the to-geosynchronous orbit launch costs, or is the cost for the entire implementation phase of the project?
Do you have a project plan in MS Project or Concerto or some other software? What is the Critical Path or Critical Chain?
Have you developed risk and sensitivity analyses?
How much is 'a lot' of PV production capability?
Have you conducted a trade-space analysis between PV and solar thermal designs, or to analyze the optimum mix between robotic assembly systems and human touch labor on-orbit? A trade study/analysis comparing lifting mass from Earth and implementing Moon-based manufacturing of structural materials would be useful as well. I would recommend an AoA (Analysis of Alternatives) between Skylon and other potential launch options. Have you identified a list of required technologies and assessed the TRL (Technology Readiness Level) and MRL (Manufacturing Readiness Level) for these?
Have you and your team developed RAM (reliability, availability, and maintainability) attributes and metrics and conducted a first-cut analysis of O&M (operations and maintenance) costs over the life of the systems?
Has analysis been accomplished to identify and estimate any potential negative unintended consequences of draining the Van Allen Belts?
Has your team consulted with the folks at the High Frequency Active Auroral Research Program to gain insight on transmitting microwave power, to include transmission characteristics through the ionosphere?
http://en.wikipedia.org/wiki/High_Frequency_Active_Auroral_Research_Program
Your proposal could possibly be the largest single engineering effort attempted by mankind.
I encourage you and your team and teaming partner organizations to further develop the details of your vision into an executable plan with acceptable cost, schedule, and performance risks and confidence levels.
Heisenberg wrote:
Responding to your reasonable questions and interest will take more time than I have today (hosting a party). If comments are left open, I will try to get something done after midnight or Sunday.
If they are not, send me an email.
I should mention that the fundamental idea of low power laser boost of a Skylon suborbital payload is only two months old. The previous article which proposed multi GW ablation lasers. Large ablation lasers are at a very low technology readiness level. This is still hard to do, but CW lasers exist into the 1/10th MW level. A scale up of 10 and installing 500 of them is a much more feasible approach at the current state of the art.
> Keith,
>
> I am curious..what does your cost estimate of $40-60 Billion U.S.
> Dollars and schedule estimate of ~ 10 years buy?
You might look at Figure 6 here: http://www.theoildrum.com/node/5485 and page 3 here: http://www.theoildrum.com/files/SkylonLaserAndCO2-2.pdf
This previous run had put ~75 GW in place by ten years and was producing new ones at ~10 GW per quarter.
> Meaning, how much
> installed capability on-orbit, expressed in number of power sats,
> number of human habitats, number of on-orbit parts and station-keeping
> thrust fuel depots, and amount of electricity generated and
> transmitted through the antennas. Also, how many rectennas on the
> Earth, and how much power will rectified and provided to the
> terrestrial grids?
Check out the spreadsheet. If you want a live copy, ask.
> Has your team determined possible locations for the
> rectennas?
No. We have no idea of what country would be making the things, though the US places low on the list.
> Is this the cost for just the to-geosynchronous orbit launch costs, or
> is the cost for the entire implementation phase of the project?
The whole thing, including developing the Skylons.
> Do you have a project plan in MS Project or Concerto or some other
> software? What is the Critical Path or Critical Chain?
No. I have MS project, but it isn't nearly as good (in my opinion) as Lisa Project that ran on the Apple computer that preceded the Mac.
> Have you developed risk and sensitivity analyses?
No.
> How much is 'a lot' of PV production capability?
If power sats are done using PV, it takes a buildup to being able to produce 100s of GW. Because of transmission loss, it takes twice as much PV in space as it does on the ground per peak watt. But you get upwards of 5 times as much power over a year because of higher sunlight intensity nearly full time.
> Have you conducted a trade-space analysis between PV and solar thermal
> designs,
Yes. That's the reason I prefer thermal designs. The Solaren design may be as good or better than thermal, but I have not looked deeply into it.
> or to analyze the optimum mix between robotic assembly
> systems and human touch labor on-orbit? A trade study/analysis
> comparing lifting mass from Earth and implementing Moon-based
> manufacturing of structural materials would be useful as well.
In the long run, that's true. In the short run, a lunar industrial base would cost perhaps $2 T, mostly for conventional rocket launch.
> I would
> recommend an AoA (Analysis of Alternatives) between Skylon and other
> potential launch options.
In fact, we are currently looking to see if a microwave powered first stage makes physical and economic sense.
> Have you identified a list of required
> technologies and assessed the TRL (Technology Readiness Level) and MRL
> (Manufacturing Readiness Level) for these?
For the Skylon part of the project, Reaction Engines has done extensive work in this area. The CW lasers are close, scale up of ten would be enough.
> Have you and your team developed RAM (reliability, availability, and
> maintainability) attributes and metrics and conducted a first-cut
> analysis of O&M (operations and maintenance) costs over the life of
> the systems?
Not yet. Much of this depends on the particular technology and that's not settled. For example, gravity gradient solves most of the attitude control problems and there is a chance that a large loop of wire interacting with the earth's field will deal with the remaining one of rotation around the tether.
> Has analysis been accomplished to identify and estimate any potential
> negative unintended consequences of draining the Van Allen Belts?
No. It's hard to imagine there being any consequences of substance.
> Has your team consulted with the folks at the High Frequency Active
> Auroral Research Program to gain insight on transmitting microwave
> power, to include transmission characteristics through the ionosphere?
>
> http://en.wikipedia.org/wiki/High_Frequency_Active_Auroral_Research_Program
No. We are using study results from out of the 70s.
> Your proposal could possibly be the largest single engineering effort
> attempted by mankind.
Money wise, it could be smaller than the Chunnel or Three Gorges Dam.
> I encourage you and your team and teaming partner organizations to
> further develop the details of your vision into an executable plan
> with acceptable cost, schedule, and performance risks and confidence
> levels.
I am retired, the others involvement is part time. So far we have kept it open source. Because of ITAR it's possible any US citizen who works on it might be jailed.
Thank you for taking the time and effort to offer your responses here.
ITAR...I am familiar, trust me!
There are a plethora of exceptionally tough challenges to this concept, and I am being rather diplomatic / understated. Note I did not say impossible, but the probability seems low.
If any country could make a run at this, it perhaps would be China.
They seem to have monetary reserves and other resources to gamble big, and they have an authoritarian government. Perhaps they could make a go at it with European and Japanese technical help.
I recommend pitching this to the Chinese...if they don't take the plunge, then I think that would be that.
I am not doing so. I am not even sure if I know any Chinese nationals, much less one I could pitch it to.
But it seems likely that someone is doing that or will be shortly.
Just wondering - which parts of this would pose huge problems under ITAR?
The problem is, you never know.
Quoting from a mailing list (not my personal experience):
Case Study from Personal Experience......
I once worked for a company who made CAD design tools for designing,
chips, boards and so forth.
All their work was privately funded, and they had never had any
government contracts.
One day out of the blue they got a letter from the DOC [Department of Commerce] (who had
jurisdiction at that time) telling them that their technology was
subject to export controls, and warning them that foreign nationals
were not be be permitted access the the sensitive technology.
Since the company had subsidiaries in several countries, and had many
foreign national employees working both on the US sites and overseas,
this was a major disruption to corporate operations.
The company responded to DOC basically telling them to get lost, and
they informed all employees of the company position (that is how I
knew about it). When I read the memo I scratched my head and had a
feeling I knew what was going to happen.
Sure enough, DOC were extremely miffed and put major heat on the
company. They had attorneys make threats of prosecution.
Finally the company took some proper legal advice, and realized that
they had to knuckle under and do what DOC said, or the executives
would face some serious jail time.
The company rapidly instituted an internal export control program, and
firewalled off foreign employees away from the sensitive technologies.
They sent another memo to all employees recanting the previous memo,
and advising all employees that we must strictly adhere to the new
corporate export control policy.
Export control over technical know-how originated in this country (USA) is an everyday reality.
For example, if you invent something in the USA and you want to get a foreign patent for it, you must first get what is called a "foreign filing license" before you can send (export) the know-how to a foreign patent attorney.
And you thought we lived in a free market democracy. Ha.
Whereas a foreigner could just read the USA patent and patent it for themselves?
NAOM
That's not how the system works (either here in USA or in other countries).
In the USA, patent applications are generally filed in secret.
Government agencies get 6 months to review newly filed and still secret patent applications for possible national security issues.
If none are found or the 6 months is up, you get a grant of a foreign filing license and you may then proceed to file in Europe or elsewhere while your US patent application remains secret.
If your USA application instead becomes published prior art before you file in Europe, you lose your right for a patent in Europe because Europe requires something called "absolute novelty". But now we're getting too hyper technical on this.
Bottom line is that you may not freely export new technical know-how out of the USA before it gets a security clearance in one way or another.
Keith,
Having been involved in planning of some large projects, and just observation of many, failure to cost things correctly is what kills many dreams.
From Wikipedia,
"The complete Skylon project has a projected R&D cost of over $10 billion and will continue for another 7–10 years"
If $10B disappears in just the R&D of the Skylon by itself, by the time 200? are built your budget has been blown out of the water. Why 200? If there is to be 3 flights/hr, then that is 72 take-offs per day. Even if on return there was only 1-2 days allowed for checking/fixing re-entry damage, and then re-fueling, 200 may still not be enough as there would be major maintenance needed every x flights that would take vehicles out of service.
Specially hardened runways are only part of the needs. Major maintenance infrastructure ,hangars, fuel tanks, methods of getting enormous quantities of fuel to the runway.
Those numbers would not get close. Skylon alone easily accounts for $100B+. If we start talking several hundreds of Billions we might get close, you need to do a lot more work on some real numbers.
I have had some experience working with costers on government projects...I will throw out a cost figure somewhere North of $1 Trillion dollars to achieve IOC (Initial Operational Capability)foe the entire space-based power sat system.
I have no detailed basis of estimate fore this...this is a 'gun to my head' WAG.
Heisenberg, I think you could be correct with the $1T+ figure. Just looking at the cost of the ISS of around $100B, and it only has a maximum Expedition crew of 7, then just to build the living quarters for 500-1000 workers will be massive. Of course there is also the logistics of all the food that will have to be taken up, displacing some of the room for the solar array equipment, then there is also construction tools etc etc.
I suspect that to get the number of Skylons happening and building the necessary space stations of size to accept the workforce would take 25 years and cost well in excess of $1T with todays availability of resources.
as Peak Oil and Peak other resources start to bite the costs will blow out from there probably by a factor of 2-3. This is of course all before a single array is installed and beaming power back to Earth.
As a means of providing power the costs are just "out of this world", however as a sci-fy afficianado I would really like to see the Skylon perfected, the laser enhanced propulsion work, the large space station in GEO orbit as a launch pad for further missions etc.
Unfortunately the realist in me sees a winding back of space programs. Governments cannot afford them as we pass Peak everything.
That seems reasonable, figure spending a trillion dollars on a TW of power which takes about ten years to put in place. Even at 2 cents per kWh, the utilities can afford $1.6 T, so your profit is $600 B.
Given the profit and the short time of energy payback, I think it would be considerably larger, maybe 2-4 TW and 2-4 times that much money spent on power satellites.
Keith,
Even in your scenario it will take 20 years to get 1TW in place, with the first units installed in 10 years time and the last in 20 years time. Companies wont look at profit of $600B in 20 years as $600B in todays money, there is this little thing called discounted cashflow that discounts the returns in 20 years time. You are also out by a factor of 10. The cashflow of 1TW @ .02/kwh x 23 hours x 365 days would be $160B, so the accumulated cashflow from year 20 to year 30 would be $1.6T.
To simplify the accounting, I have been assuming that the power sats are sold to power companies for ten times annual revenue. So the cash flow to the construction company building a TW/year would be $1.6 T per year--which sounds like a lot of money until you start thinking about the size of the oil market.
The reality is that power this inexpensive would result in a gold rush as it rapidly displaced other sources, starting with electric generation, but rapidly taking over transport either as electric vehicles or as input to synthetic fuel plants.
I think you would get market saturation in the 20-40 TW range.
Building an additional 15 TW and operating them for 20 years (300 TW-years) would provide enough energy to turn 100 ppm of atmospheric carbon into synthetic oil. Pumped back into depleted oil fields, it's the one way of sequestering carbon that seems to be safe for millions of years.
Spent oil reservoirs are subject to changes like subsidence and may not seal nearly as well as they originally did. If you're going to store carbon in them, heavy waxes are probably a better bet than oils. Waxes are also much less miscible with water if they do leak.
It happens that Sasol's F/T process makes heavy waxes which are then cracked for diesel fuel.
I think that 7-10 years is optimistic for even getting prototype engines flying, take some of the hypersonic test projects as examples. Just the support structures will take years, hypersonic, high altitude wind tunnels to test vehicles and you can count on prangs. Also Skylon is very sensitive to weight creep, wouldn't take much of an increase in skin thickness to wipe out the freight load.
NAOM
Oh, It does take that much and more. When this thing get going it cost $50 B a year to lift 500,000,000 kg at $100/kg.
But that's not a problem because the power satellites are worth far more. The only question from an investment standpoint is how deep you go into the hole before selling power satellites starts to pay off the investment. Once they do, the payback of the invested capital takes around two years. After that it coins money even with serious additional investment. You would kind of expect that from something with an energy payback of under two months.
I did an exercise on the Skylon numbers a while ago, deleting the Sabre engines. Interestingly, if you use the same propellant volume as the Skylon C3 (1440 m^3, derived from assuming the same LH2 and LOX mass ratios as given for the smaller C2 version), replace the Sabres with SSME’s and then change the mixture to the 6:1 ratio LOX:LH2 of the SSME’s, the higher LOX fraction of going all rocket means the runway mass increases to 525 tonnes. Keeping the structural weight the same but adjusting for the lighter SSME’s vs Sabres, and Using an Isp of 350s to 10,000m and 450s thereafter, in theory even with a 15 tonne payload, you still get to orbit!
It appears to me that the secret to Skylon's feasibility is in the weight of the dry mass excluding the Sabre engines, which is just 34 tonnes for a space plane that's 83 metres long, to illustrate, it's claimed that the aeroshell will be just 0.5mm thick.
Q1: Weather modification. Could additional sunlight be directed to low pressure areas to counteract tornado formation?
Q2: Orbits. Could near-sun orbits be used to collect energy?
We are currently already running an earth-changing experiment by releasing gigatonnes of CO2 in to the atmosphere, and the outcomes are not pretty or readily undoable.
Then I read an article like this about pouring microwave energy onto the surface of a planet that's already in trouble. I get very nervous.
We're just finding out that radio waves are not too good for us (cell phones as an intense example), and here we have a proposal to pour microwaves down n us from orbital antenna. When all is going well these antennae will have a lot of 'light-spill' outside the receiver array which will impact on the surrounding countryside's biota in unknowable ways.
And of course when we can no longer service these things reliably and they loose lock on their ground stations the down-rays will simply wander randomly around over the face of the Earth, illuminating what ever happens to be beneath them at the time.
And by then no one will be able to up to 'turn them off' or make them safe.
How do you de-orbit them?
I think its a very dangerous idea.
The finishing touch for me was to come across the phrase:
"Drain the Van Allan belt..."
This offered by the promotors without any obvious appreciation of the utility of the Van Allen Belt on life on Earth. Without the Van Allen Belt we are toast.
If the promoters of this system are able to talk about 'Drain the Van Allan belt' without the slightest recognition of the likely implications of this action, what other known unknowns are they going to ignore.
Sorry, but its nonsense.
Next!
Could you explain how the Van Allen Belt has an effect on life on earth? Note that I said the belt, not the magnetic field.
The Earth is protected by its magnetic field which is created by the rotation of the planets core, that field acts as a mirror in trapping energetic particles in the Van Allen belts, mainly protons in the inner belt, electrons in the outer belt.
The belts don't create the field, it's the opposite.
I Wonder how the numbers would look if we took into consideration the current and future biophysical costs of coal fired power generation emissions? Perhaps as a 'Coal: a climate change cost/benefit analysis'.
http://en.wikipedia.org/wiki/Ecological_economics#Nature.
There is work being done on rectifying antennas at sunlight frequencies, perhaps using plasmonics.
http://en.wikipedia.org/wiki/Visible_spectrum
http://en.wikipedia.org/wiki/Rectenna
http://en.wikipedia.org/wiki/Plasmonics
Nano-Rectenna For High Efficiency Direct Conversion of Sunlight:
http://www.mms2011.org/Presentations/03-Siciliano.pdf
Research and development of Plasmonic rectenna arrays for light:
https://www.fbo.gov/index?s=opportunity&mode=form&tab=core&id=a79d5d4fba...
They can be 80% efficient.
"The rectenna concept for solar energy collection rests on the dual wave/photon nature of light. The recent developments in nano-technology and manufacturing ..."
Keith,
Thanks for giving legitimacy to the idea of energy from space.
What shocks me more than anything is the talk upthread about "cheap" and "economics".
Eventually our Sun will run out of fuel and die.
If the human race had not by then spread its space wings and moved to other solar systems, then all our accumulated "money", all our so-called "wealth" will flame out in a puff of illusionary smoke as the Sun and the last of our hopes peter out.
It will be one of those cosmic "oh oh" joke moments like when a dying billionaire realizes on his death bed that he can't take any of "it" with him to the maybe-its-there after-life.
If "we" can't spread into outer space NOW, as our Oil Age comes to a close, then we may never after this be able to make that necessary-for-continuance leap. After the oil has run out, it will probably be too late (unless the cold fusion myth comes into reality) to do so.
As the Talmudic query goes: If not now, when? If not us, whom?
Three-way L5
As a post mortem to the above comment (if that is indeed the right description), I see our civilization as now caught up in a 3-way insanity tug:
1) Those who stoically prepare themselves for "The World After Abundance" ,
2) Those who cornicopiciously prepare themselves for "The Coming Technological Singularity", and
3) Those who are steeped in the religious belief that "money" is real rather than a pure fantasy fabricated by the human mind in order to hide our more vicious natures, namely, our under the table decisions regarding who "deserves" to live (if at all) and who to do so well [ i.mage.+]
_____________________________
As it is said: In the land of the blind, the one eyed man is ...
called a 3 marbles shy of sanity, kook job
That's the big picture.
So fear, hope, and reality?
I would see the Archduid's point of view (PoV) as beinga form of stoic despair and surrender. (Let's give up and scale down).
I would see the Singularity people as suffering from irrational over-exuberant optimism.
As for "reality", none of us can see it.
All we can see are the shadows of our Plato caves.
Well, that's odd. I see John Michael Greer's (the Archdruid's) view as one of facing up to reality. I don't think his suggested response to that reality is at all despair or surrender. You clearly have read little of his work if you think that.
This from his latest blog entry:
neltnerb provided this observation:
So I looked around and found this comment in Wikipedia:The operative term here (my emphasis) is "suggested." In a perfect world, microwaves would behave nicely and stay inside their fencelines.
Sure, you might be able to engineer this contraption to be a power station. OTOH, if, as neltnerb suggested, we were to promote this opportunity to the military ... better yet, Dick Cheney ... someone on the team might "suggest" that they secretly design in a little button for Dick to push so he can concentrate the beam if he ever gets mad at his hunting partner again. ("Oooops, sorry matey! That musta felt kinda hot.") Certainly the military-minded conscience will be relieved to know that they can move right in after their ray gun does its job: it's not going to stay hot and messy for generations to come, like those nasty nuclear weapons.
I'm amazed that, after 250 posts and still coming in hot and heavy, no one else in this erudite, analytic crowd has pestered our author or our peers to put meat on the bones of such claims (i.e., you can't possibly design it to focus to a lethal level, some x kW per square meter). I'm not from Missouri, but my grandmother was, and she'd be turning in her grave if she found out that I read this and didn't raise the question.
I'm amazed that, after 250 posts and still coming in hot and heavy, no one else in this erudite, analytic crowd has pestered our author or our peers to put meat on the bones of such claims
It was mentioned the last time the "lets build Solar based power IN SPACE!" was mentioned. Keith had no answer then, just like he's got no answer now to the micrometeorites or the observation that the 300W/m2 beam-down rate is less then 2X better the PV capture rate of 170W/m2.
Average power of terrestrial PV: 1 kW/m² peak * 0.25 duty cycle * 0.17 efficiency = 42 W/m².
Average power of rectenna: 340 W/m² * 1.0 duty cycle * 0.8 efficiency = 270 W/m².
If your critiques got anywhere close to the target, they would be worth addressing. But with your errors WRT Keith as WRT me, you fall into the category of "that's not right. It's not even wrong."
I'm not much of an E&M guy, but I believe that focusing a microwave beam is incredibly difficult to do. Not sure why, but everything I've ever seen is that the microwave beam is going to be hard enough to focus down to a 10km wide spot (requiring a 1km wide transmitter). So, I assume that it's something that can't be done easily. If it could, I imagine we *would* go with a narrow spot on the ground as it would be higher grade energy and presumably be easier and cheaper to extract. But I don't believe that's an option.
Not that space solar power is actually an option, mind you, I'm just playing along with the thought experiment.
Actually, it will require millions of transmitters, each beaming power on the order of a kilowatt from a sub-antenna a meter or so wide. This is about as difficult as making your average microwave oven. The rest of the work is just keeping them phased properly.
If you want to satisfy yourself, try integrating the complex phase (cosθ + i sinθ) of the transmitted waveform over the visible width of a multi-km receiver and see how it works out. There are no surprises here, it's not even particularly difficult math; basic integral calculus will do if you aren't afraid of complex numbers.
The diameter of the beam is proportional to three things: the inverse of the diameter of the transmitter, the distance from the transmitter, and the wavelength of the beam. There's no way any of those can be decreased significantly by some secret design modification.
Just a thought
I wonder if this system would be more practical if instead of building huge arrays, could you use clusters of small arrays. Each one small enough to be launched in a single payload. This eliminates some of the obstacles like:
• the extremely high up front costs of a single huge array, you could add to the clusters over time,
• forget maintenance, just de-orbit defective arrays and send up new ones
• Problems with vibrations etc would be must easier to deal with in smaller system
As much as I'd love to see this, I doubt I will in my lifetime, human nature and politics are the biggest obstacles. If we just took 25% of the military spending and pushed it into this and other alt energy plans the human race would be fine, but it won't happen.
Nice job thinking of alternative constructs!
Two concerns come to my mind:
1. Station-keeping between swarms of small powersats
2. Can all the powersats in a cluster focus their microwave beams on the same rectenna independently, or do the beams all have to be in phase with each other...if so, then I suppose the cluster could be configured as a distributed phased array transmitting system, but I am not sure of the complexities involved with that.
My limited understanding is that this is exactly what Solaren plans to do. Phase a constellation of small satellites together. Where the separation between the satellites allows a smaller spot size on the Earth than possible using one big antenna.
http://en.wikipedia.org/wiki/Thinned-array_curse
"The thinned array curse means that while synthesized apertures are useful for receivers with high angular resolution, they are not useful for power transmitters. It also means that if a filled array transmitter has gaps between individual elements, the main lobe of the beam will lose an amount of power proportional to the area of the gaps. Likewise, if a transmitter comprises multiple individual transmitters, some of which fail, the power lost from the main lobe will exceed the power of the lost transmitter, because power will be also be diverted into the side lobes.
The thinned array curse has consequences for microwave power transmission and wireless energy transfer concepts such as solar power satellites; it suggests that it is not possible to make a smaller beam and hence reduce the size of a receiver (called a rectenna for microwave power beaming) by phasing together beams from many small satellites.
A short derivation of the thinned array curse, focusing on the implications for use of lasers to provide impulse for an interstellar probe (an application of beam-powered propulsion), can be found in Robert Forward's paper "Roundtrip Interstellar Travel Using Laser Pushed Lightsails"
Note that the thinned array curse applies only to mutually coherent sources. If the transmitting sources are not mutually coherent, the size of the ground spot does not depend on the relationship of the individual sources to one another, but is simply the sum of the individual spots from each source."
In other words, the "thinned array", the individual satellites or propulsion lasers , can not advantageously act as a single phased array with its hoped-for ability to focus tightly. The individual sources are best scrambled relative to each-other. They will then illuminate the target like that many flashlight beams all flooding the same spot.
http://en.wikipedia.org/wiki/Robert_Forward
http://www.transorbital.net/Library/D001_AxA.html
(machine read, OCR, and reproduced...)
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http://en.wikipedia.org/wiki/Laser_weapons
On March 18, 2009 Northrop Grumman announced that its engineers in Redondo Beach had successfully built and tested an electric laser capable of producing a 100-kilowatt ray of light.
http://en.wikipedia.org/wiki/MIRACL
"It can produce over a megawatt of output..."
Chemical lasers are the other choice: Good old hydrogen-fluorine or the more modern oxygen-iodine. Hydrogen and fluorine are hypergolic. When introduced into a resonator, the chemical reaction pumps the lasing action. Adaptive optical systems can be used to keep the beam focused on the target despite the trails of shifting lenses formed as the air roils turbulently and tries to get out of the way. Adaptive optics can also stabilize the mode of the resonant cavity. It is hard to beat chemistry for delivering power.
http://en.wikipedia.org/wiki/Chemical_laser
http://en.wikipedia.org/wiki/Adaptive_optics
(These are both terrible articles.)
MTHEL CIWS demo. Uses adaptive optics:
http://www.youtube.com/watch?v=9V1pkTMCZ0M
http://www.youtube.com/watch?v=cCBwLJjzDJQ
Not practical.
Kirk Sorensen at
http://energyfromthorium.com/
started out trying to promote this idea as a NASA engineer. That's when he became converted to nuclear and then liquid thorium fluoride reactors.
If you like nuclear, continue to promote this idea. Just getting everything into space let alone fixing it would be astronomical(no pun intended).
The question of how many watts you get per square meter on the ground is a fundamental one, since the question is almost always asked about the power rate rather than the amount (power per day or per month). Since ground solar has a capacity factor (operates) between about 5% and 25% of the time at the rated capacity of the collectors, that means the other 75% or 95% of the time (depending on the site) you are getting zero power and all of that billion dollar installation is sitting idle.
On the other hand, the space solar installation has sunlight essentially all the time, with a capacity factor of about 99%, so while the ground solar site does get in many sites about half the power rate of space solar AVERAGE, if you add up the kilowatt-hours or Gigawatt-hours over an average 24 hour day or 720 hour month you will see that a typical ground solar plant will get 1-6 hours of power per day while the space solar plant will get 24 hours of power per day (by switching to a spare satellite a few times a year.)
Since few or no utilities have attempted to use ground solar as a source of base load power, they have not faced the financial brick wall of the oversize collectors and giant power storage systems that would be required. A current estimate for a single Gigawatt of base load power in a southern US city is about 65 Billion dollars inlcuding the storage system, and that is just for a single average 24 hour period with an average amount of clouds during the winter.
What do you do when you have several cloudy days in a row?.
John
What happens when this solar array gets hit with meteors or space dust some of which would hit it with a lot of energy?
.. or gets hacked, or gets a virus, or the financing collapses, or the 'adapters' (pick your unexpected weak-link in the chain..) keep burning up, or cracking, or feeding back.
This requires a test, or a series of tests before most of this conversation can really even START.
"In theory, theory should work like the real world, but in the real world, it's almost never the case..."
Playing some more with the idea of frequency conversion.
The solar-thermal proposal draws fire related to vibration, wear, heat-sink/heat rejection, and leaking. The photo-voltaic has efficiency problems. The system function is to turn light into microwaves.
Light is an electromagnetic wave. It can be received by antennas and processed like any radio wave. Visible light is covers one octave of wavelengths centered at 550 nano meters. Infrared is even longer. AMD is fielding integrated circuits with 32nm features and Intel has its new 22nm transistor: very small structures are routinely fabricated.
http://en.wikipedia.org/wiki/22_nanometer
The light could be received with micro-fabricated antenna arrays, converted to microwaves, and re-radiated.
BIGGER and SMALLER:
There is an old antenna called the rhombic. It is typically 5 (five) wavelengths on a side. That is almost 4 microns long for visible light. That's huge! You could see it with a microscope! The rhombic is inherently broadband having over 100% bandwidth and it is very directional, having high gain. It points towards the target with that end being terminated and energy flowing out the other. One could put a reflector behind it to give any missed power another pass and take energy from the near end, too: an old dog trick (that's why their eyes are so reflective!).
There is a laser called the coated particle plasmon laser. It is 20 (twenty) times smaller in size than the wavelength of the radiation it produces. It has a gain of 10,000, so it oscillates easily. Such an approach could reduce the size of the microwave components.
CONVERSION:
Capture the broadband radiation with a broadband antenna array made of micro-fabricated rhombics or of log-spiral cones, say. Rectify to direct current and drive microwave oscillators. Couple the oscillators to narrow-band radiators.
Capture the broadband light with broadband antennas and block down-convert to the microwave region... a trick borrowed from cable TV! Radiate the energy using broadband antennas. Beam the "local oscillator" up from the receiving station. If the array wanders off-target, the L.O. or pump source goes away and the energy stops flowing.
HEAT SINK:
There would be no need to construct the "cold side" for a thermal engine.
All just for-instance examples, but the idea is presented?
http://en.wikipedia.org/wiki/Rhombic_antenna
Really, really fun paper:
The design and simulated performance of a
coated nano-particle laser
http://arxiv.org/ftp/physics/papers/0612/0612192.pdf
Errrr 1.5db path loss ?
This post should be bookmarked at TOD as a quick litmus test for gross systems blindness. It's a cognitive blind spot which very smart people can suffer from, and which has been exacerbated by the primarily reductionist/specialist definition of "expertise" and academia in modern western culture.
I take no particular joy in pointing this out; doing so is about as aesthetically pleasing as euthanizing an excess litter of kittens. I like kittens, and I like projects in space. There's a scorched hunk of the original skylab on my desk as I type this, as reminder of being present for the last Saturn V launch.
The thing is, the fine details of the design don't matter. The gross details don't even matter. Yes, it is theoretically physically possible to mobilize the fossil energies available to an industrial race to move into space, to loft huge structures into the skies and live and work in them. That would have been cool.
Yet this proposal is self-evidently impossible on its face for systems reasons. Can you see the number in the attached image? If not, you're color blind. Can you immediately see, on a quick skim, that this plan is effectively impossible in our existing context? If not, you're blind to the nature of probabilities in evolved interacting systems.
It is physically trivial to build a swine-rendering factory in Central Park. The tech is well-established, and quite clever design innovations could answer any technical questions. However, I'll go out on a limb and note that prior to a collapse of the economy, there will not be a swine-rendering plant built in Central Park, and it has nothing to do with the fine points of the design. Though the smart money would bet on the odds of that rendering plant over this space armada.
Mind you, I'm speaking as a fellow who earlier in life interacted with Gerard O'Neill and bought into his vision; which even in 1970 is was a huge longshot, but then we had people on the moon and a bit of cultural momentum going. Kids born since then will never look at another planet and correctly know there are humans there. Kids born now will probably live to see GPS stop working, and weather satellites fail and not be replaced, because that's the trend and we're on the cusp of cascading collapses; fast or slow, those collapses are baked into the cake at this point.
I've been with a team bouncing an ultra-strong laser off the reflector left at a lunar landing site, measuring the moon's distance to a fraction of an inch. Hugely cool, but there are limits to what actually gets built by our civilization, and giant lasers to launch payloads won't. I've also worked in the world of legislators, budgets, pressure groups, lawsuits, public policy, and treaties; humans as they exist and not as we might imagine them in a scifi novel. Good scifi writers know this well.
Someone on this list, several years ago - I think Nate - suggested a term, "The tragedy of the energy-investing commons", for the predictable rush of investment into utterly-impractical projects once it became clearer to the masses that our available energy will drop off a cliff. That is, there will arise a huge cry to "do something", and those who make the decisions for us (and for their own excess financial wealth) are spectacularly ill-equipped with the mental tools to sort the grain from the chaff, which is why TOD and a few places like it are potentally very valuable in that context. The value lies in doing that sorting, which is why I'm euthanizing this particular kitten.
In the real world, even in the flush of civilizational "peak net energy" before the cascading collapses it has been hugely difficult to get a tiny set of solar panels deployed on a hugely expensive space station in LEO with no real mission, even with the combined resources and nominal focus of the entire human race. The space shuttles blow up or crash about every 80 launches, so have been retired because that sort of thing bums out the public. After its current missions, the space station will probably soon stop being visited even by antique soviet boosters & spacecraft. It is a vestige of past times, a living fossil like the tuatara or coelecanth. One may wish humanity had made different choices; but we, like other species throughout deep time, are stuck with reality; which includes the path-dependence of evolving systems.
I don't doubt the pure motives of those sincerely pushing this kind of proposal, I share them, I'm one of them and I love them for it on a deep level. Just as I admire the faith of some family members in an angelic afterlife, I admire the pursuit of tech for good cause, and the rapture of losing onself in theoretical mental triumph over physical barriers presented by the straightforward laws of nature. Eating of that lotus is tempting, so tempting...
More crassly, there is a boatload of money to be made by milking the hopeful and idealistic as well as the simply naive, and that niche will certainly be filled. I could start a space power company tomorrow with a slick website and soon follow it with an IPO, and make myself bloody rich. I have the contacts, the track record, the cred, the experience to make such a company work... as a company paying me a salary. Hell, I could probably land lucrative government grants, even get laws bent, I've done it before. I could have gangs of fun with fancy plans, press releases, celebrities, eccentric billionaires, toy rockets.
But it would not be an ethical thing to do. We are on the verge of a terrible bottleneck that will revert our species to something like historic population levels on a despoiled planet, and are already well into a mass extinction event. To the extent any of that can be ameliorated, it will be by those who can get things done in the real world, using the scarce resources likely to be available.
This proposal is mind candy, nothing more. Yum.
What do you think of airborne wind turbines, or power kites
Personally, I love them. I've been playing with designs for them for years.
There are parts in your cell-phone so small, they can't be seen with even the very best optical microscope. How crazy is that?! They would be greatly out-gunned by a T4 bacteriophage.
Those pesky humans have been thinking about space-based power even before their first visit out there.
http://en.wikipedia.org/wiki/Space-based_solar_power
Issac Asimov wrote a story in 1941!
http://en.wikipedia.org/wiki/Reason_%28short_story%29
They even put up a mirror for a moment:
http://en.wikipedia.org/wiki/Znamya_%28space_mirror%29
Further, it's patented... meaning this fellow, Peter Glaser, who then worked at Arthur D. Little, Inc., as a vice-president, thought something might come of it soon.
http://www.google.com/patents?id=y9cvAAAAEBAJ&printsec=abstract&source=g...
And these folks will be really disappointed at your news. They have a contract to deliver 200MW from space to PG&E in California.
http://www.instablogsimages.com/images/2009/05/04/space-based-solar-syst...
http://en.wikipedia.org/wiki/Solaren
The monkeys think about all this stuff... then something comes along that surpasses their dreams, like the laser.
"Those pesky humans have been thinking about space-based power even before their first visit out there."
Lots of people have thought about things that couldn't happen or haven't happened.
"Issac Asimov wrote a story in 1941!"
They've also written stories about them.
"They even put up a mirror for a moment:"
Yes, try #1 sort of worked. try #2 failed and try #3 was abandoned.
"Further, it's patented... meaning this fellow, Peter Glaser, who then worked at Arthur D. Little, Inc., as a vice-president, thought something might come of it soon."
Having a patent means something? Really? List of crazy patents
"And these folks will be really disappointed at your news. They have a contract to deliver 200MW from space to PG&E in California."
Lots of people have had contracts to deliver something and haven't delivered. I bet they've been disappointed too.
What does the last turquoise diamond mean? ..with energy storage..?
My impression is that represents the cost of actually storing energy from the PV system rather than simply covering the lost amount with more panels but no storage.
The article:
http://www.greendiary.com/entry/solaren-to-capture-the-sun-raw-in-outer-...
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Here is the Japanese spaced-based power system JAXA
http://msnbcmedia4.msn.com/j/MSNBC/Components/Photo/_new/091202-space-ja...
The Japanese are even more interested in renewables after Fukushima.
http://axisoflogic.com/artman/publish/Article_62659.shtml
The race is on!
http://inhabitat.com/japan-plans-21-billion-solar-space-post-to-power-29...
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Here is a blog on space-based solar power:
http://billionyearplan.blogspot.com/2010_08_01_archive.html
And another blog on space power:
http://powerfromspace.blogspot.com/2011_04_01_archive.html
There is a video there on SSPS: Space Solar Power Systems
More of the Solaren story:
http://spot.us/pitches/445-is-solar-power-from-space-the-next-big-thing-...
Here's another link to a JAXA report, dated 2004:
http://www.on-orbit-servicing.com/pdf/OOS2004_presentations_pdf/OOSIssue...
The link about SOLAREN quotes "Darel Preble, a Georgia Tech University physicist and chairman of the Space Solar Power Workshop", who has offered comments on this post...
E. Swanson
Thank you, greenish, for a very succinct post. All through my life I've been one of the "techno-geeks" that like to think about things like this. But I can see that we have virtually no chance of even starting on this type of journey. Why can't some people begin to see that there's no way we can even begin something like this when we're already sliding down a slope of resource depletion? What makes you blind to the fact that our cities can't even keep their sewer systems maintained and our electric companies are deferring maintenance on their infrastructure? We're having huge conflicts over paying for Social Security and Medicare, ballooning deficits and you think that you'll get something like this boondoggle financed? This would be by far the biggest, most complex system ever attempted by humans.
Didn't anyone watch the problems getting the last set of solar panels deployed on the ISS? Multiply by a bazillion! You want multiple flights/day for years when there are complaints about the pollution and ozone layer damage of just one shuttle launch?
Those like the one downthread who keep saying that "we have 6.7 billion mouths to feed" "what are your solutions", well, I read something recently that I can't remember where. Maybe on TOD, maybe some book. Sometimes what we face is not a "problem" but a "predicament". You can solve the problem, but you face the predicament and just have to deal with it. Not every unpleasant situation you face is a problem that can be "solved". Maybe it was a problem several decades ago when there were things we could have done to solve it, but now we've already jumped off the cliff.
Same thing with saying "we need to get off the planet and colonize space". Sure, start a journey with all resources supplied from an earth with the same resource depletion problem.
Yes, thank you greenish.
We are so accustomed to inexorable technical progress and exponential economic growth that we tend to forget what made it all possible: cheap and plentiful petroleum products and energy.
Almost all of our modern habits and assumptions are based on these resources. Without oil or natural gas, many things we take for granted would not be possible or would be greatly reduced... rockets, satellites and moon landings, aircraft & air travel, automobiles and asphalt, worldwide warmaking, chemical and mechanized agriculture, nuclear power, advanced medicine, micro electronics, plastics and composite materials, automatic space heating, etc. Not to mention our planetary population of almost seven billion humans.
The resource situation has changed, and it's taking us a while to adjust our expectations. Masses of orbiting solar collectors beaming microwave power to a vast electrical reception and distribution grid are the kinds of things we might have been willing to imagine and develop when we thought we had unlimited oil and gas to burn. From now on, we'll have to content ourselves with more modest proposals.
Ironically, it's the perceived shortage of fossil fuels that prompts us to consider things like space-based solar power. Back when we could have conceivably built such a system, we didn't think it was all that important because oil and gas were so easy to find and use.
Cheap and portable petroleum fuels have encouraged us to believe we are awfully clever and powerful, when actually we are just very lucky to have been born during the age of oil discovery and extraction. Now that this short historical era is almost over, our cleverness is about to be fully tested if we are to maintain even a semblance of our present technological civilization.
I've followed the peak oil debate closely, and I fully appreciate the limits of a finite world, I recognize that we face serious challenges over the next 50 years and that if we get it wrong, things could go very badly for us. There's something else that I recognize though that you seem to have overlooked. I don't know everything, you don't know everything. What actually happens over the next fifty years is yet to be determined, and all paths are possible that aren't excluded by the laws of nature or by human nature.
I doubt several aspects of this plan that Keith has outlined are realistic, but there's more than one way to skin a cat, so it or a version of it remains possible, and only someone overcome with hubris would claim certain knowledge of how things will unfold over the next few decades.
I haven't overlooked it. This path IS precluded by aggregate human nature, as long as we're talking about nations anything like those which now exist.
I certainly don't know that you can't break the bank at Las Vegas starting with a $5 chip, but I have a pretty good guess that the odds are low.
So you think that some other version of a huge microwave space armada may be more practical than this one? I'd disagree on probability grounds, but I'll be happy to look at the plan.
Doing a rough probability estimate isn't hubris; ideally, it's part of seeing the world as an adult. A quick logical filter to avoid waste.
You're indulging in a logical fallacy. "Everything is possible, so this thing might happen". Well, no, we're not talking about a quantum wave-function here. Any proposed societal project which falls below one-in-a-trillion odds of success on cursory review is impossible for all practical purposes.
I certainly DON'T know everything. Just the basics to be a functional human. I recommend them.
It'll swing on the economics, I doubt that the great leap Keith hopes for is practical. If it happens, SBP will become feasible after launch costs come down as a result of private companies finding a demand for such services for other customers, the most likely course to me is the steady expansion of space tourism as costs are brought down. The most likely route for that is TSTO HTHL, such a system if operated as efficiently as current air services, could take one tenth of the payload mass to orbit as is now carried by long haul flights with a given amount of fuel and hardware. That would make ticket prices in the low tens of thousands of dollars possible. At that price the market size gets into the hundreds of thousands of passengers a year.
That obviously has nothing to do with the actions of "nations anything like those which now exist" which just illustrates that you haven't looked at even the most obvious of the possible ways by which it could happen.
Economics IS one facet of aggregate human nature.
So... space tourism will drastically drop launch costs to orbit? I hope so, really. As for TSTO HTHL, my Klingon is a bit rusty & google doesn't recognize it either. So how long until the first orbital passenger flies on anything other than an old soviet rocket? And how long after that will it take for the launch cost to come down two orders of magnitude - one won't do it. Oh, and we'll be in a fiscal depression soon.
Hundreds of thousands of paying passengers going into orbit every year, now you're talking! Unlike my planet, where airlines are consolidating in a frenzy not to go bankrupt from $100 oil, and mostly WILL be bankrupt at $150 oil. I guess that will free up a lot of passengers to go somewhere.
Yep, I reckon that's the most obvious way, all right. Millions of intrepid space tourists every decade, each deciding to pay tens of thousands of dollars to be ferried to low earth orbit for some reason, undeterred by week-long projectile vomiting and spectacular crash footage with charred body parts raining down every month or so.
And THEN we can start building the giant microwave power-station armada with our extra money. Got it. The invisible hand of the marketplace.
Well on my world the airlines move around 5 billion passengers and 80 million tonnes of freight a year, so I'm only talking space tourism numbers of 0.01% of what the airlines carry, so I'm glad I don't live on your world.
Perhaps you need to enter some other key word, maybe "rocket" or "spaceplane", that's the best I can do since I strongly believe TANSTAAFL.
I like you, you're silly.
If you can't be bothered to post a link, I'm not sure why I should try random google searches.
Ironic, considering your line of argument, that you'd invoke tanstaafl. But I hope you get that free launch, courtesy of the space tourists.
Over and out.
Andrew;
The ONLY thing that would allow a 'Space Tourism' industry to survive, much less flourish, is the imbalances in our Global Economic models that has created a class of Ultra-rich, some of whom might be viable customers.. and yet their ability to pay is directly predicated on a system that has been making our global economy stagger into overload, with the largely intentional sacrifice of the Middle-classes.
Just because you can reach escape-velocity, doesn't mean you won't still come crashing back down. You have to follow the whole trajectory.
Those "imbalances" are what allowed the airline industry to get established and to evolve to the point that even middle-class commoners like me can afford a ticket.
Well if you've reached escape velocity you won't come crashing down as long as you don't run into anything. Are there uncertainties? Yes, that was the point I was arguing with Greenish about, he seems to think his great wisdom allows him to see years into the future, I wonder if he saw the development of shale gas? I doubt it.
Andrew said: 'Those "imbalances" are what allowed the airline industry to get established..'
No they aren't, the 'Mainstream air transport' industry Grew WITH the middle class, and with the emerging apex of cheap FF. Now, cheap FF are flat to declining and the soon-to-be-ex-super-wealthy are hoarding with every trick imaginable and then some. The airlines for 'everyman' are hanging on by their nails. Remember the good old days last year when you could get a packet with about 4 peanuts in it?
The Wealth margins today are not those of the 90s or the 70s.. the Ponzi Scheme has metastasized and is quickly and blindly eating the host. Space Planes and Weddings on the Titanic are not long for this world, I think.
TSTO: Two Stages To Orbit http://en.wikipedia.org/wiki/TSTO
HTHL: Horizontal Takeoff, Horizontal Landing http://en.wikipedia.org/wiki/HTHL
Easy to find, they even have there own wiki pages for Pete's sake. I often come across acronyms I don't know, faced with the choice of whining at the person using them, or looking them up, I just look 'em up, horses for courses I suppose.
Greenish argued that all these hundreds of thousands of people would just be going into orbit to vomit. Surely it's obvious that as tourist numbers grow and you move from the pioneering stage to true tourism, the facilities evolve to cater? One of the important and obvious steps would be rotating habitats.
He also suggested that the launch systems would be unsafe, but again, as systems evolve safety improves. What's proposed is simply the same process that occurred with the evolution of the global tourism that's already happened.
No. I think the group-vomiting experiences of the first few loads will be widely reported and will disincline others.
If you need to build the hotel first, that adds a large upfront cost and threshold. Ignoring huge thresholds seems the ostensible leitmotif of those disagreeing with my assessment.
Systems have evolved since the '60's; the odds of dying on a space shuttle flight are about 1 in 40, and on a russian missile on the order of 1 in 100 I think. You're proposing entirely new methods, done cheaper than NASA or Russia can do it. I think that in the initial years, the loss of a vehicle every 100 or so launches is probably charitable based on decades of data on trips to orbit. How will the media cover that? How will it affect demand?
If you're suggesting that a new design will be, out of the blocks, orders of magnitude safer than anything ever launched, great; state it explicitly upfront, so that claim can be examined for credibility.
I'm bailing on the discussion, because it devolves into the same form as debates over religious dogma, which are always useless.
The first would be pretty basic, just a couple of Bigalow space habitats, with a centrifuge.
Keep in mind that every time a new model of airliner is developed we don't go back to the type of design faults that doomed the Comet, new models continue to improve in safety on those before them. There's little that's new in what I'm talking about, we have reusable rocket engines, we have a winged spacecraft that lands on a runway, we have TSTO.
The main reason that the system I'm talking about isn't operating already has a lot to do with how space is now run, it's controlled by state agencies which are unfortunately just political footballs, there's no interest in catering to or encouraging tourism, in fact NASA has had real hostility towards space tourism, as seen in NASA's attitude towards Dennis Tito's trip.
Another problem is that 10:1 ratio I mentioned earlier, for a reasonably sized payload (say 20 tonnes)you need a winged vehicle (2 stages) with a combined take off weight of around 700 tonnes. That's a huge up front investment. There is a way around that though with aerial propellant transfer (APT), an existing airliner (probably an A380) could be converted to refuel an orbiter at 12,000 meters, that way the only entirely new vehicle that needs to be developed is the orbiter, which would only weigh about 40 - 50 tonnes dry.
APT isn't a new idea, and though 12,000 meters at Mach 0.85 doesn't sound like making much of a difference, that 1.2 km/s that it takes off the required delta V of the orbiter has a huge effect on the payload mass ratios.
LOL
Nice graphic.
Some would argue that it is incomplete because there is a second a$$et situated in that round glob above the shoulders.
That higher up a$$et is a bigger problem than the one located below the elbow.
At least with the lower a$$et you know what kind of sh*8 hangs around in there.
On the other hand (or elbow), the upper a$$et is full of unknowable unknowns that get us into much deeper sh*8.
greenish, you may be right for the US, too many people share your dismal mindset. But the US context is not the only one.
Re the paragraph starting: "More crassly . . . " I simply don't believe you have the ability to "start a space power company".
Re after "an ethical thing to do," it's a dirt cheap cop out. There is at least one way I can think of to get the whole population through the bottleneck, even for an earth with "scarce resources" that can support only a billion people. Heinlein saw long ago.
[Break to go read it]
I wonder how much of this doom and gloom is the result of people just getting old and realizing they don't have long to live?
Of course, that's not my problem even if I am older than most of you.
Keith;
I do appreciate your persistence with those that you see as bringing doom and gloom. I think their challenges aren't merely despair and denialism.. I'm also not convinced this is a workable system, though I'd be eager to see you who are convinced perform some sort of a Proof-of-Concept and have my errors repealed.. but I think this proposal is simply too top-heavy, which is what I think I hear Greenish saying about it as well. Too many plates spinning, way too high. Depends on so much high-end transport, a large crew living off-planet, a massive financial investment for a theoretical return that has more bottlenecks than you seem willing to entertain.
I mean, what if the market just can't sustain the price of a KWH? What keeps the supply and repair ships moving, the crews and ancillary industries paid up?
Like Nuclear, I have to guess that this would do less to generate stability, and more would simply depend on it in order to support the layers of complexity that are necessary for it all to function. I don't particularly buy a total collapse scenario playing out in 'Epic Movie Timeframes', but I do think we need to create systems with enough resilience to suffer wars, relocations, droughts and depressions.. I think these could be visited upon the 'Peaceful West' which has had an unusual 6 decades of calm (inasmuch as we were able to outsource much of the unpleasantness to our obliging poorer neighbors)
I'm pretty young (46), and I'm not hopeless about our situation.. just a bit scared.. and I just don't find your plan very plausible. Please prove me wrong.. it does sound like fun.
Bob
There's a difference between viable and competitive.
This plan is viable, but it's not competitive. Plain old wind, solar (and nuclear, etc) will be all we need.
I would have put it the other way around.
It's really competitive, 10-20 times less expensive per kWh than wind and solar, and 3 times less expensive than nuclear (before you count the cost of Black Swan events).
It's seemingly not viable due to a front end cost of less than ten 1 GW reactors.
Your point: this plan could be done.
My point: it could be done if it were really, really needed....but it isn't.
I would argue that if you include the cost of risk that this is more expensive than plain old terrestrial wind, solar, etc. This is a very large scale project that takes a while and requires the performance of a number of moving parts. The cost of risk caused by very large scale is real: it's what often kills 1GW reactors, and what makes 25-100MW reactors very, very attractive. So, if we quantify the cost of large-scale risk, we would find that plain old wind, solar etc was cheaper.
I think the difficulty of scale is what Greenish is really talking about.
There is a value in evaluating projects like this - it reminds us that we have a number of viable alternatives. That's sufficient to make such analysis worth doing, and why people shouldn't "dump on it" prematurely. Nevertheless...I don't think we're likely to need it.
It depends on what kind of world you want to live in.
Liquid fuels from electricity are roughly $10 capital plus $20 x cost of power in cents per kWh.
1 cent $30/bbl
2 cents $50/bbl
...
10 cents $210/bbp
20 cents $410/bbl
It's not like anyone is going to build a plant to make liquid fuels at $210/bbl for a long time. We will go after a lot of really low grade oil and make oil out of coal before we do that.
If you are concerned about carbon, this is not the world you want.
It will be a world where only the rich travel by air.
The risk element of scale is not the giant power sats, but the 25,000 flights per year with 20 ton payloads. It looks promising, but it's not obvious that can be done even with Skylon and lasers.
However, I don't think anyone can make a case that power satellites make economic sense with conventional chemical rockets.
Perhaps I should not be so dogmatic about it. If you can get the product of $ per kg and kW/kg under $500, and all the rest costs $1100 or less then power sats make sense.
I do feel that going much below 5kg/kW isn't going to be easy and going much below that number starts getting into light pressure problems.
It is worth noting that the energy cost to GEO, even at ten cents a kWh is only a $1.50. Over the present cost, there is lots of room for improvement.
I don't think liquid fuels are needed on anything like the current scale.
Wind power will provide all the power we need for about $.08 including the cost of managing intermittency and transmission.
Direct use of electricity is far cheaper than synthetics. Extended range electric vehicles are the sensible solution: use electricity for 90% of miles, and ethanol and synthetic liquids for the remaining 10%.
Aviation can be made 3x more efficient over the next 40 years, which will make $170/bbl liquid fuel perfectly affordable for middle class travel.
Finally, if we really want affordable synthetic fuel, it wouldn't be hard: if we overbuild wind power we'll have a lot of really cheap power most of the time - perhaps $.02/kWh - which we can use to synthesize fuel.
---------------------------------------------------------------------------
One thing we'll need to synthesize fuel is very large scale electrolysis of sea water - have you seen any cost estimates for such equipment?? Or perhaps a good breakdown of the current costs of electrolytic hydrogen?
At high energy prices I wonder if there will be any middle class?
It's dominated by the cost of electric power.
Round number, 50 kWh/kg or 50 MWh/t, 2 tons of hydrogen and 12 tons of carbon for 14 tons of fuel.
At high energy prices I wonder if there will be any middle class?
Oil will very likely be somewhat high priced, but electricity won't. An EV (or EREV/PHEV) at $.12/kWh will have a total cost of ownership less than an ICE at $3/gallon. Aviation at 150 passenger-miles per $10-gallon would cost 6.7 cents per mile, which is perfectly affordable. Industry will drop expensive oil like a hot potato, just as everyone dropped it for interior lighting 100 years ago, utilities dropped it for electrical generation 30 years ago, home owners are dropping it for space heating, and drivers will drop it for travel.
costs of electrolytic hydrogen? It's dominated by the cost of electric power. Round number, 50 kWh/kg or 50 MWh/t, 2 tons of hydrogen and 12 tons of carbon for 14 tons of fuel.
hmm. How much would electrolytic hydrogen cost if power was only $.02/kWh?
Dollar a kg.
Just above you quoted me saying 50 kWh/kg. Multiply by .02
But I have no idea of where you are proposing to get 2 cent power. I know of nothing current that will get there and there are good reasons to expect solar and wind won't.
It also makes me wonder about your other numbers.
I'm trying to get at the capital cost: the total hydrogen cost minus the energy input.
The 2 cent power is easy: just over build wind power, and use the excess power at cheap rates.
Conversely, we can charge an average market rate for the power sold to the hydrogen plant, and then we've solved the problem of windpower rates falling at times of excess production.
Either is good.
If you're only running the electrolyzers a fraction of the time, you have to divide its amortization cost per unit at 100% by the actual duty cycle. For a 15% duty cycle, multiply by 6.7.
Sure.
Wind farms produce more than average power levels from 40-50% of the time (all of the children are above average...). If we overbuild wind by, say, 25%, then wind power output will be more than the baseline average probably 67% of the time. There will be a minimum surplus needed, of course, but it seems likely that we'll get at least 50% utilization.
So, seen any costs for very large electrolyzers? Ideally, with capacity figures that would allow a $ per kg of H calculation?
If the price of a kWh from some other source went well below 2 cents per kWh, then the organization building power satellites would simply go out of business. Having the market vanish is one of the risks investors take when they invest their resources.
This is what happened with Iridium. The stockholders and debt holders lost everything when cell phones took over most of that market.
From a larger perspective, would really low cost energy be worse than what we have now?
Actually, I'm ardently pro space exploration and use of space, as stated. As much as you are. I'm not saying I don't like the idea of space power in principle, I'm saying that this proposal is unrealistic. I have never said any of this stuff on space power websites, I'm only saying it here because TOD exists largely to test ideas against reality. On a space power website I'd pick up the 'contact high' and suspend my disbelief.
So you think starting companies is difficult? Not so. I could pretty easily do as I stated, but that's irrelevant to the point. You may treat it as a rhetorical device if you'd rather.
You must misunderstand what I was saying. I don't think YOU are unethical. Hell, I said in a previous post I loved you. Rather, my doing it knowing that it would ultimately fail its stated objective would be unethical. I think you are admirable.
Heinlein saw a lot, I love him, too. Which way do you mean, he worked a lot of story angles.
Getting older really does bring you up against cascading collapse in a personal way.
However, I'd say that gloom and doom is a subjective thing ascribed to others, based on overly-rosy expectations of the universe. We simply didn't think about the downslope of the green revolution, or the finite nature of crucial resources. Anyone who has accomodated the real world seems doomy to those who haven't. Personally, I'm an optimist. I just don't seem like an optimist when compared to prevailing cultural narratives.
I sincerely wish you luck.
Space based solar power, if you can get it big enough and cheap enough, is a solution to peak oil.
I am making the assumption that you think the price tag and/or timeline is unrealistic.
I am a big fan of "design to cost." There isn't any reason not to extend that to investment though that is not normally explicitly done because it typically takes very large investments to get the unit cost down.
I don't think ~$40 B is a large cost in the context of an oil import bill of $12 B/day. It's no larger than the bail out of the auto companies, and much smaller than what the treasury put out to shore up AIG. But YMMV.
What level of investment and time do you think would make a compelling case to do it?
Or is there *any*?
Heh. There is a big difference between what I'd do if I were czar of the world, versus what I estimate can be done in the current situation. As I raised myself on a diet of Heinlein, my solutions would be similar to what I think his might be, and quite radical by current standards.
I was entirely committed to the L5 concept in the decade after I first met Gerard O'Neill, but that sort of thing - if possible at all - would take something on the order of either a brilliantly directed command economy, or a Liet-Kynes prophet-like merging of ecological goals with most of the planet's religions. (Neither of which is likely to occur while the complex infrastructure necessary to deploy a network of space power satellites still exists, which is to say the coming decade or two.)
There's a reason Heinlein remained a scifi writer instead of becoming planetary czar. (Though Spider Robinson wrote a nice story about an alternate timeline). Our society, our species in aggregate, is neither sentient, sapient, nor sane by any reasonable standards. Our evolved tribal-monkey imperative for egalitarianism has produced representative governments which stifle innovation, and only react after a crisis.
The financial marketplace is also ill-equipped to innovate on a large scale and generational timeline. Perhaps that's why Solaren has a less-impressive website, with far lower information content, than my wife's hobby dog-training business. They're going to deliver 800 gigawatt-hours of space power to PG&E by 2016? Really? Is there anyone on the planet who believes that? Sure it's a fun PR exercise, win-win for both parties to the contract, but it is misleading to the majority of people, and their elected reps, who have a simple set of mental tools.
Personally, I think it's ridiculous to require innovations to compete on a dollar basis, because so many real costs aren't included. The horrific cost of rising CO2 levels. The cost of degrading the earth's carrying capacity in other ways. The various war & paving subsidies to the culture of the automobile, the hidden subsidies to the existing scheme of fission reactors, a by-product of the cold war.
Yet, as a 60-year-old who has done some innovating and run a lot of companies, I've had to deal with the dynamics of what can and can't be done in the existing systems. I've pushed the boundaries far enough that I have a thick FBI and CIA file just from acting more like a sovereign nation at times than as a person running corporations. Like an outback aboriginal, I have become sharply attuned to the environment I've spent time in - in this case, the environment of competing systems and ideas which constitutes current human society.
I'm critical of unrealistic plans because I hope to see realistic ones emerge. As things stand, we're not on a track to build solar power satellites. Not the USA, not anyone. Certainly, there are many people in many nations who haven't yet "got the memo" about the impending liquid fuels shortage, or haven't looked at the implications of declining net energy on the feasibility of business as usual. But soon, governments and businesses will be in crisis-management mode more or less permanently, and looking for quick payback on fixes as their infrastructure crumbles. Any project plan which is not resilient to that sort of thing simply won't succeed; and will by its nature pull resources from some plan that might.
I presume you know who found the L5 Society.
But you didn't answer the question.
Or should I take it that you don't think it could be done even if it could make money with a chump change investment?
Reason I ask is that further application of the same method might be able to get cost down another order of magnitude and the time to a few years.
Political refugee and jail time because of a cult and corrupt courts.
Send me an email, my address is at the top. At least we can compare horror stories.
With a Google I see you have a colorful history.
Keith wrote:
Lets see, US imports of oil and oil products are about 10.8 million barrels per day. At about $115 for Brent these days, that works out to be about $1.2 Billion a day. Your calculation appears to be off by a factor of 10, if I understand what you wrote...
E. Swanson
Right, dropped a decimal point. So the investment would be just over a month of oil imports.
Thanks for catching my error.
That's a great comment, Greenish. And here I was thinking this thread was about played out, and that I wasn't likely to find anything more worth replying to. Glad I checked anyway.
I agree with you that it's important to recognize the difference between what is possible, in terms of physics and technology, vs. what is realistic. Your example of building a swine-rendering plant in Central Park is a good one. But I'd raise one large and important caveat: people's notions of what is realistic are almost always extrapolated from what they've experienced in recent history, and that's a very fallible guideline.
Recent history is a good guideline in a purely statistical sense. In the absence of specific knowledge, predict that tomorrow will look a lot like today and you'll most often be right. But ocassionally you'll be wrong. Sometimes very wrong. Sometimes something you'd have sworn could never happen, does. "A 9-plus magnitude earthquake and a tsunami that will overtop our sea wall and flood all our backup generators? Why that's totally unrealistic. We have records going back hundreds of years, and we've seen anything like that! Our reactors are perfectly safe!" That sort of thinking is also what made it so hard for people to believe that we could be approaching the day of peak oil. It's "the tyrany of the accustomed" in its influence on our thinking. It's also why the neglect of serious history study in our schools is such a tragedy.
You're quite right that SSP is a complete non-starter -- in our economic system as it works today. In a market economy, no one could possibly raise the hundreds of billions of dollars needed for a power satellite program. The horizon is way too long, and the risk way too high. The physics of the problem don't allow it to be tackled in small incremental steps. In a world where investment capital is supplied by wealthy individuals and banks looking for a good return, solar power satellites cannot happen. But is that the only way the world can be? If you think it is, aren't you perhaps as much a victim of the accustomed thinking as the deniers of peak oil?
Take a long view of history any you'll find that capitalism and our current system of working out what does and doesn't get done is an anomaly. Throughout most of human history, great projects were undertaken simply because the community, its rulers, or its priesthood, chose to do so. For one reason or other, they felt is was worth doing, and they proceeded to direct what had to be a huge fraction of their GDP into doing it. Stonehenge, the pyramids of Egypt, and the cathedrals of medieval Europe are the probably the most familiar examples, but there are a great many others. Not a one was done to return a profit to investors.
Capitalism is in crisis, though the denial around that issue is probably greater than the denial around peak oil. Given that crisis, along with the example of a flourishing economy elsewhere that is still committed to central planning and national goals, is it unrealistic to think that matters could change? If it turns out space solar power really would be the most cost-effective alternative to fossil fuels if you make the necessary investments in launch infrastructure, is it so unrealistic to suppose that a national -- or international -- committment to building it could arise?
Of course, that's a pretty big "if". As it happens, I think that an accelerated program of 4th generation nuclear power plants, possibly in factory-produced modules, is a lower risk and more workable alternative. But we'll see.
Given current technology and no advances, perhaps so. It has always seemed to me that reactors are the next best after power sats, though when they have problems, they are *big* problems.
With projected nanotechnolgy, even the radiation mess from Chernobyl and Fukushima could be cleaned up, though I expect that humans will just be made immune to effects of low level radiation and ignore it.
Post nanotech though, it's debatable if they should be called human or not.
Thanks for the comment. Obviously you don't know me, but I operate with a long perspective and long timelines, and my explicit awareness of the "black swan" dynamic preceded Taleb's by at least a decade.
I fully agree that projecting the recent past as "normal" is a trenchant human fallacy.
I speak not of the ways the world could be, but of the world as it is today, because that's a salient constraint. Evolving systems like, life, ecology, economy, politics are utterly subject to initial conditions. The frozen accidents of history, including our past decisions or ambivalance, have deposited us at this moment with certain evolved systems, a certain distribution of wealth, certain cultures, certain entities, etc.
This will certainly evolve, and nobody knows exactly what the exact status of the system will be in the future; it's not just unknown, it's unknowable in principle. However, it will evolve according to rules in a stepwise way. The window of opportunity for building out something like these satellites is quite short, and the process is fraught with complexity and unknowns. It isn't certain that even weather satellites or GPS will be replaced over the next 20 years. In 50 years, the likelihood of such a project even being possible is low. We couldn't rebuild a Saturn V now to save our lives. We could build something sort of LIKE it, but the vast network of expertise and sub-plans was lost when the program was cancelled, and downsized with automation, so we'd be starting from scratch.
As you say, we'll see.
Who takes horse-drawn buggies through geosynchronous orbit on pleasant Sunday afternoons?
The combination of geostationary platforms, massively large antennae and gigawatts of available electricity have revenue potential far beyond bulk electric supply dirtside. They have many other possibilities other than direct revenue. If we in the USA were really smart, we'd have taken that high ground first.
Here is the problem.
It is not going to go away.
We have 6.7 Billion mouths to feed.
Empirical evidence suggests that with pristine soil and water the planet can support 1.1 Billion in desperate circumstances without Oil.
So what are your solutions for the 5.6 billion who have no place. Kill them? What are you?
This is not mind candy.
If there were a very large supply of energy available to replace that from oil or the other sources of fossil carbon, there would still be the problem of limited area for crop production. Agriculture based on monocultures is unstable and requires constant management. Efforts to increase production per unit of land only acerbates the management and resource problems. With unlimited energy availability, population growth might continue until the next limit is hit, what ever that might turn out to be. At some point, it is reasonable to expect that mankind won't be able to overcome the next limit and the population will crash. But, energy may already be at a limit.
So, the only long term solution would appear to be to limit on population or force negative growth. Given mankind's genetic predisposition to procreate, achieving a limited population means that there won't be as many births as might otherwise occur, which suggests massive birth control efforts, including abortion and enforced sterilization, with the present level of science. Without that, the excess population will die before reaching their natural end.
It would appear that what must happen is that people must either die unborn in the womb or die in the streets and in the fields. Not a pleasant future, is it???
E. Swanson
Let us succumb quietly is a generalization that can be appended to any thread.
I think I would prefer the Euthanasia Parlor to the Geriatric Ward, should I live that long...
E. Swanson
I suppose that the cornucopian technomage solution will be to put huge farming colonies into orbit.
NAOM
Silent Running.
Is this a reply to my post? I take it as such, due to the "mind candy" quote, even though it was not correctly posted as one.
Your reply is constructed illogically, and your ad hominem baiting isn't appreciated.
In a simple rephrasing of your position: "The problem is dire, therefore this particular solution is reasonable." "And if you don't agree, you're in favor of murder and you may be evil".
Sorry to have to make a point of it Arthur, but you're babbling and frothing. Your argument logic could equally well argue for a proposal to run industry on synthesized unicorn poop, or to dedicate our remaining fossil energy to sending distress messages to friendly aliens.
I don't care for the existential predicament, which is why I've spent my life working to make it less dire. As I said, I take no joy in pointing out what should be trivially obvious, but that's why TOD exists.
So what are YOU going to do about the 5.6 billion? Something useful and practical? Please share.
If it is our primary goal then no one has to die from war or starvation this century.
A strict one-child policy would get us down to a billion people in approximately a century. With increased resource/energy efficiency, development of all available renewable resources, conservation and a reduction in living standards we would get there with room to spare.
Of course the real question is how many of the changes needed to meet this standard are actually achievable.
I think everyone can agree that an optimal solution is impossible. Millions of people will starve or be slaughtered this century. But a partial fix is better than none at all. Rather than worry about all that is not being done we need to focus on the achievable steps that will take us closer to a sustainable society.
The magic way of doing this is with an immaterial field projected from the planet.
Less advanced is a cloud of material points above the atmosphere. Each tracks, receives, converts, and redirects the sun's energy. It would be a homogeneous solution: Each payload into space would be the same. The system is operational immediately, growing in power with each launch. No assembly required. A swarm exhibits graceful decline as individual members fail. The commercial space ventures already under development are suitable for carrying a multiplicity of cargo rather than massive structural members: they might do. Perhaps ground-based lasers could supply the nudges and energies for functions like orbit maintenance.
It is good to explore such things. Come on out and play! There are things in this thread that have application right here on the ground. The final result will look nothing like the early chalk-board drawings...
http://images.usatoday.com/tech/_photos/2004/05-13-spaceshipone-main.jpg
As greenish, Black_Dog, and augjohnson point out, these guys are good to go:
http://www.metmuseum.org/toah/images/h2/h2_19.73.209.jpg
One need do nothing. The population will track resource availability all by itself.
Well, yes. They are ready to go straight up and straight back down.
They are missing the 28,000 kph horizontal vector.
Thats why SpaceShip One is the size of a 4WD, while anything that gets into LOE with a cargo worth mentioning like an Atlas V, Energia, Aeres V and Arieane is unbelievably huge by comparison.
And yes, you are right about the population and our general response to these difficulties; we are on track for a low-energy future, whether we do anything or not. There's no need to fret!
I'm glad that this is a technology which is being seriously considered. I would kill to be a project manager on this kind of job.
What are your thoughts on conversion efficiencies? Considering technologies like the carbon nanotube solar cell enhancements being developed by MIT could dramatically improve solar cell efficiency at incremental cost, it seems to me we could pretty rapidly reach a point (like in the next decade or so) where this is in fact the cheapest energy source around, if someone comes up with more efficient launch systems.
This is the kind of stuff that gets my spine tingling! Where do I send my meager resume?
When all is said and done, Kieth has done us all a big favor by writing and posting this article;and he has done a good job of defending the central thesis too.
But he only presents the whole ball of wax as being about "conceptual progress" iirc correctly what he wrote in the original post.
I doubt if he would put his OWN MONEY into any such scheme; he never says such a system WILL be built.
I have read this forum as extensively and as carefully as any member for a couple of years, in my own humble opinion, and I have learned a lot here, in addition to finding confirmation to a lot I learned other places.
I'm afraid those who believe we can actually build such an enormously expensive and incredibly complicated power system have failed to absorb perhaps the biggest single lesson to be learned here-BAU is a wobbly old man subject to shortness of breath, exhaustion, and at high short term risk of a stroke or heart attack-not to mention that he has a terminal case of resource depletion cancer which is going to kill him anyway within the next decade or two..
I used to describe myself as a conservative, but the crowd here is so ardently antirepublican, with good cause certainly, that i nowadays choose to refer to myself as a realist.
I get climate change, resource depletion, pollution, loud and clear-being technically and scientifically educated has everything to do with that, rather than politics.
Barring a miracle, the only vehicles that are going to be going into space in large numbers are ICBM's.
Get real, folks.
I have taken it on myself to try to disillusion some happy go lucky campers here who believe that we can feed ourselves from city gardens or by building skyscraper farms.
I'm a real farmer who has read a lot of great science fiction, as well as such classics as "Farmers of Forty Centurys".
Frost wiped out my fruit crop again this year, and excessive rain has prevented me from planting my row crops until this week-yields will be off drastically as a result.
And there is not a damned thing I can do about either problem.
Fertilizer and pesticides and containers cost more every trip to the farm supply.
Not a damned thing I can do about that either.
We will be importing at least two or three potentially devestating bugs or weeds every year from now on so long as international travel and trade continue. Someday one of them will turn out to be the agricultural equilavlent of the Black Death and wipe out the corn, wheat or soybean crop.
Can't do anything about that either.
The countryside is filling up with immigrants, mostly illegal, in my area , really fast.My own family is having children at about a 1.6 clip per female, but the local population is growing fast.
I think highly of my new nieghbors, they are fine hardworking people, and fully expect within the decade to have nieces and cousins and nephews with lovely Spanish names and features, but at some point enough people is ENOUGH.
Nothing will be done about this as the environmentally conscious elite of the country has decided to turn a blind eye to this problem, seeing immigration as a human rights and political issue trumping environmental considerations.
Anybody who cannot see where BAU is headed simply hasn't studied the problem with an open mind.
Faith is not confined to the religious people so often disparaged here.
People who actually believe in space power, or any of numerous other techno utopian schemes are exhibiting either a lack of understanding of applied elementary probability theory or else simply ignorant of the state of the world we live in or both.
I am not arguing that such a system could not be built-EVENTUALLY, IF bau and eternal growth are accepted as givens.
Technically, it might be possible, as I remarked earlier-engineers, manufacturers, and entrepeneurs build on the shoulders of thier predeccesors.
I am saying that in a time and resource constrained world, it isn't going to happen due to the simply mind boggling number of interlocking problems that would have to be solved at simply mind boggling and entirely unmanageable expense.
OK, I ask the same question I asked of greenish: How far down would the cost of this project have to get before you would consider it worthwhile?
Perhaps you could put it in multiples (or a fraction) of the daily cost of oil imports.
HI Kieth,
I'm afraid i must refer back to your title for the article - no doubt there has been a great deal of "perceptual progress".
The problem is that it has not been matched by actual engineering and manufacturing progress.
Hardly any of the hardware necessary to put such a scheme into practice actually exists, and when it does exist, it is simply totally inadequate in present form for the job.
You are talking about solving literally tens of thousands of problems that are ALL individually very tough nuts-a lot of them will prove to be totally intractable after ten years of work-necessitating the scrapping of large portions of any previously developed subsystem involving that particular problem, and maybe going back to the lab-not the engineering dept-for a new solution.
There aren't enough engineers, inventors, entrepeneurs, scientists, and capital in the world to solve all the problems within a meaningful time frame.
Perhaps a simple example will suffice to gert my point across.There are literally thousands of people spending billions of dollars trying to solve just ONE such problem-achieving a self sustaining fusion reaction.
After several decades, they have not yet achieved the equivalent result of banging two rocks together-and if and when they achieve the reaction, then the apparatus they are using will be to a working fusion reactor as that campfire started with rocks is to a fine diesel engine or a computer chip fab plant.
The point is that there was a market for any workable diesel, or any workable chip-that sort of development paid its own way and bootstrapped itself.
After many years with generous funding, the Pentagon still doesn't have a decent laser weapon-the ones that they have are so overloaded and overstressed that they self destruct with a single use within a millisecond-they MIGHT still manage to knock down a mussile or an aircraft of course within that millisecond.
I'm not an engineer, but I did take a math course once upon a time that included basic probability.
When many, many cutting edge problems must be solved silmantaneously, the odds of achieving a successful outcome of an engineering project approach zero pretty fast.
You aren't talking about just finding a solution to a problem-such as creating a few grams of some suitable alloy or compound in a lab-if it is needed in any quantity, you must also create a whole new manufacturing process and scale it up just to have that one alloy or compound available.
We would need literally hundreds of new industries to be created from scratch to manufacture or process materials that haven't even been invented yet.
Bau is a sick old man.The days of eternal growth are over.
If throwing money at this problem would solve it, I would be on board with you.
But we don't have it, and we can't divert it from oil imports-in that respect, we are damned if we do, and damned if we don't.
Anyway, it is not possible to buy what does not exist-namely enough talent to solve ALL OF THE COUNTLESS PROBLEMS within a meaningful time frame.
Well fought, OFM.
This topic just makes me shake my head.
If I heard they were testing some of the key challenges for real-world functionality, I'd tune in and watch a bit, but I'm with you.. there's just too far between here and there, and not a great convincing argument that there's even a there to get to.
Time for some 'show us', Keith.
Conceptional progress. New approach, combining the projected suborbital payload of the Skylon with a laser boost to get the cost to GEO down under $100/kg. (At least in theory.)
Skylon has been worked on for a long time. The extremely high performance heat exchanger in the engines is the only part that didn't have an existing example. Reaction Engines has manufactured big samples of the heat exchanger and verified that they don't frost up.
Fundamentally I am talking about a rocket with an exceptionally high exhaust velocity that comes from getting hydrogen really hot. How hard can it be to use a laser to heat hydrogen? What else does it take? Pumps? We know how to build pumps and these are not at all exceptional.
May I remind you that it took about 4 years to go from nothing to nuclear weapons dropped on Japan.
Fusion is a fundamentally different kind of problem. This is relatively simple engineering mostly with mechanical parts. The really hard parts with respect to the laser, large solid state devices, already exist.
You are two years out of date.
"Firestrike High Power Solid State Laser Fires 105kW Beam
"Northrop Grumman has claimed a world record achieved by its high-power solid state laser, firing over 105 kilowatts (kW) laser beams from its scalable Firestrike laser building blocks. The test was performed as part of the final demonstration milestone of the U.S. military's Joint High Power Solid State Laser (JHPSSL) program (Phase 3). A government team reviewed results of the demonstration during a System Test Data Review held Feb. 10 at Northrop Grumman's Directed Energy Production Facility in Redondo Beach, Calif.
"The achievements included turn-on time of less than one second and continuous operating time of five minutes, with very good efficiency and beam quality. Leading to this achievement, Northrop Grumman reported last year reaching a JHPSSL Phase 3 power level of 15.3kW in March and a power level of 30kW in September."
There is no reason this design will not scale to a MW. Then we buy 500 of them.
I see. So how did the US succeed with the Manhattan Project?
And this is bad how?
For the has been country called the USA, maybe so
It's a minor point actually. If the US doesn't solve the problem, someone else will.
There are an awful lot of under or unemployed engineers. Friend of mine works as a security guard and tells me of a dozen he knows who are doing that. And the number of problems certainly countable, and probably less than Boeing faced building the 747.
One question: What do you consider "a meaningful time frame"? Before starvation hits the US?
The government of the United States of America is down to its last manned space mission. This is an image of failure that is every bit as powerful as the propaganda of success and the true exuberance that followed John Glen's first flight. Perhaps this is why there is such dismal response to any discussion of a bright future.
It is plainly over in the U.S.. Like Warren Buffet said, “There’s class warfare, all right, but it’s my class, the rich class, that’s making war, and we’re winning.”. The Evangelicals are on the rise, too. There is plenty of money to be made right here riding the system into the ground. The End-Times are coming, anyway. Why bother?
Only hope, and now, need, is new. Things like this could have been done instead of building the useless and soon to be abandoned space-station*. The technology was in place thirty years ago.
Perhaps future presentations should feature just the lifting means. Reference everything else to demonstrated works? There was a lot of research done on focused microwave weapons. There were successes. Hughes Electron Dynamics had its broadcast power work in 1976-1981. The main fellow continues on elsewhere. The Northrup laser work I gave youtubes for takes out artillery, mortars, and rockets without, itself, degrading. It solves the phase conjugation problem with a quite Victorian mechanistic approach called adaptive optics. To present all of these other system aspects along with the lifting means overwhelms the audience and invites empty commentary deriding already proven prior art.
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*The space station that was made is not a stepping-stone into space. It ate all the money for "big science".
I guess I'll reply to this here, since Keith thinks I haven't answered.
First, if it hasn't been evident - and perhaps it hasn't - I love the stuff Keith Henson does, has done. I tip my hat. I think the L5 vision was wonderful, and I've long been emotionally invested in space engineering, conceptually, to alleviate the problems caused by industrial humankind on earth.
However, the fact that I'm emotionally invested is cause for caution; humans have a tendency to have a lot of blind spots in their thinking, and indexing those blind spots is an ongoing process at best.
Life, and complex systems which arise downstream of it in what we might call the extended aggregate phenotype, such as our economy, politics, culture, narratives, built infrastructure, etc, go through a stepwise process of evolution in which each step must be viable in its existing context. A system doesn't just tunnel into existence fully evolved, it's an iterative process of trial and error in which no nonviable evolutionary states can be occupied.
Perhaps the biological concept of "fitness landscapes" could be useful to help visualize this, I'm sure it's googlable for those unfamiliar with it. Anything which, given initial conditions, is expected to evolve to a given end point generally doesn't; and the landscape can contain many barriers.
A swordfish couldn't evolve into a genetic dragonfly, and it would take a bloody long time for its descendents to occupy anything like a similar place in fitness space through convergent evolution, even though in principle, you could get dragonfly-like descendents from swordfish progenitors, and the dragonfly piece of fitness-space is quite viable.
Why? Because the sequence of successive contexts necessary to turn a swordfish into a (phenotypic) dragonfly, with the intermediate creature continuously triumphant against fierce tooth & claw competition in all of them, is fantastically unlikely.
Moreover, such context-dependent iterations take finite time for the intermediate states to exist.
I realize that swordfish & dragonflies may not seem a great metaphor for space power, I'm just putting some basic concepts out here, and one never knows what will bubble out of my brain before coffee.
Here's why I use it: It is technically possible for swordfish to evolve into phenotypic dragonflies. Even straightforward, just a matter of shuffling DNA and sorting it. That's the reductionist view, and it is not incorrect. No new technology needed, it's all on the shelf or demonstrated. However, from an evolutionary perspective - which is a systems approach - swordfish evolving gossamer wings and chasing mosquitos are self-evidently not ponies to bet on.
It has been suggested that the space power satellites can evolve into existence in the free market if a few thresholds become lower by several orders of magnitude, such as the cost to get a kilogram to GEO. Even if one ignores the fact that something like that - which consists of a huge number of problems which have never been solved in such a way - may be framed as a single conceptual constraint in verbal logic, one still is faced with the time for the system to iterate/evolve to gigantic geosynchronous microwave power stations. If that process would take 50 years - and it well could, this stuff has been an exciting but "fringe" idea since I was lecturing small groups on it in the early '70's - then that will take us into a different era, into a time when the only jet contrails in the sky are military aircraft, after current nations have dissolved and realigned, after probably 1-4 billion humans have died off through accelerated causes including wars, disease, and famine.
I'm saying that space tourism - which is at best a niche demand currently, even with a vibrant world economy coasting on the infrastructure built over past decades with millions of years of fossil fuels - will not evolve, of its own accord, in the time available, into giant microwave power stations in GEO. It's a swordfish/dragonfly deal. Even if a benificent deity pictured that end state and wished it to happen within 20 years, She could not achieve it through evolution.
I note this since space-power proponents seem to sometimes get the "free market" entangled in their minds with a "command economy" situation, which is a different kettle of swordfish. Yes, the Manhattan Project did a lot in a short time. It was absolutely an existential, budget-no-object, war-footing balls-to-the-wall, get-nukes-before-the-Nazi's-do dynamic, decided by fiat. And even so, when it comes down to it, you can get a fission explosion by banging rocks together, if they're the right rocks. Half a critical mass of U235 in each hand, clap 'em together, and there you go. Once refining the material, which is also straitghtforward (if expensive) due to mass differential, you could build one in any machine shop. The plutonium bomb was more sophisticated, but was mainly a timing problem. The problems had no high physical-reality thresholds other than the straightforward process of using fossil energy to concentrate U235, and the process could ignore being viable in the short term because it was incubated, like an egg under a penguin's butt.
Thresholds are a big deal, and something we're going to become more aware of. It's hard to evolve past them. Looking at the natural living world through fitness-landscape glasses, even looking at human civilizations that way, and you see that they exercise a lot of control over what happens and what doesn't. Orbit is a big threshold; not a lot of stable states short of it.
Launching payloads to orbit with rockets is a mature technology. No, it isn't the only way, it's just the most simple, robust, straightforward. There are definitely better/cheaper ways possible in technological fitness space. However, their evolution is at an early stage still. If we weren't facing collapse, they might evolve; then again, if we weren't facing collapse, there might be no societally-perceived need for them; and evolution is always about the current generation, not a hundred generations out. Evolution has no preferred direction.
So to answer Keith's question: I think it would be hugely worthwhile to have clean, functional, flawless microwave power stations in orbit, and financial cost be damned. It's not a question of "worthwhile". It's a question of whether there is ANY remotely plausible sequence of events which could cause that to occur while it's even remotely physically possible with the energy and materials available. I don't see one, and I've been looking since the early '70's. We're farther from it than we were then, by a longshot, in evolution-space.
The money cost of this project, at this stage, in this time, is only one parameter. One can't get to a pre-decided target state in the human/earth system by tweaking a single threshold. Moreover, it isn't a foregone conclusion that it would be possible even with unlimited funding, as I think oldfarmermac correctly points out.
I realize I won't convince anyone who doesn't see it immediately for themselves; just trying a different tack to clarify my perspective. All best to Keith, and those like him.
Excellent comment Greenish, one that cannot be left without reply.
The reason I see space tourism as a route to SBP is based exactly on the reasoning you use.
The biggest step is getting that first few tourists up, and that's been done, between them the first half-dozen have paid around $150 million for their flights.
The evidence is strong that NASA has become an organisation strangled by bureaucratic red tape, what they do, using the rockets they use could be done by organisations competing in a freeish market for a quarter to a tenth of the price NASA does these things for, and that's based on what NASA estimates it would cost them to do what SpaceX has done.
NASA has always been hostile to space tourism, if you go through the history of that opposition to allowing paying tourists to fly on NASA spacecraft, the arguments against it, it's not surprising it's been so slow to get off the ground. Killing space tourism seems to be as important to many NASA administrators as killing weeds to a gardener, it's like they know if it's not killed it could take over.
There are routes for a steady progression from a few super rich tourists to mass tourism, cost can go down enough as new systems are developed to cater for increasing demand. The energy cost of putting one person and half a tonne of ship into orbit is only about $750, and starting with aerial propellant transfer, (cost less than $50,000) a ticket, introducing rotovators (cost goes down to less than $10,000 a ticket)it could happen in the current economic climate. As far as the time for it to happen, I'd liken the potential growth rate to that which occurred in air transport between the two world wars, in America only 6,000 air passengers were carried in 1926, but in 1941 (the tail of the depression) American air services carried 3 million passengers.
http://www.answers.com/topic/air-transportation-and-travel
I am not one of the people who think that.
And chemical rockets will not get into the cost range you must have for power satellites to make economic sense.
The best we have, hydrogen/oxygen rockets has an exhaust velocity of 4.5 km/s. To reach LEO takes 9 km/s. That's a delta V factor of two, a mass ratio of 7.4 and the empty mass can only be 13.5 % of liftoff. Reusable takes 15% structure. So you can launch a chemical rocket to LEO, but you can't reuse it and it carries no payload.
Skylon cheats because up to when they run out of air, they have an equivalent exhaust velocity of 10.5 km/s.
That's a non answer if I ever saw one. Obviously if it could be done for a million dollars it would be. The fact that you can't see a "plausible sequence" doesn't mean other can't.
We know we can get to GEO, been done at least 100 times. The problem is to reduce the cost, that needs a first stage you can get back that lofts a substantial second stage as a payload and an effective way to get most of that to GEO. The key for doing that came out of the solid state laser business where they were into cutting steel.
There might be an even less expensive way, and no, I don't expect you, or anyone in the US to do it under any circumstances. This is being written for other eyes and they are looking.
Just being pedantic but they're actually aiming for 35km/s equivalent during the air breathing phase of the flight (and because of the weight of the Sabres they need all of that).
I back calculated it and got 10.5 km/s
Normalized by thrust in rocket mode, how do the SABRE engines compare in mass to SSME?
This from the SKYLON User Manual on the Reaction Engines website:
Working from the 14:1 T/M ratio that's often given for the Sabre's by Reaction Engines, the mass of the two engines combined is around 19 tonnes.
That unladen mass of 53 tonnes minus the engines doesn't leave much for the rest of the (83 meter long) vehicle.
There's nothing particularly surprising at such a high calculated Isp given that it's just the thrust per kg of fuel used, and in air breathing mode the H2 fuel will only constitute about 1/35th of the propellant (assuming a 6:1 O2:H2 ratio).
My email is up at the top of the article.
If you are serious, there is a need for an informal program manager right now.
Unpaid unfortunately.
But it might not take all that much for it to reach the stage where people are putting in money.
Or maybe bit coins.
Laser demo using atmosphere:
http://www.youtube.com/watch?v=Q07kZS13DEc
Space elevator games, 2009, Dryden:
http://www.youtube.com/watch?v=zO1EV6A76ZE
http://en.wikipedia.org/wiki/Elevator:2010
The Space Elevator is great science --- Fiction! There are so many reasons it won't work that it's laughable that NASA is still considering it. Here are a few problems:
1. Lightening, which could strike the tether and burn it up. Were one strike to break the tether, the balance mass would pull the tether into a new orbit, like a slingshot. The tether extends thru the atmosphere and would provide an easy path for lightning between the ground and any storms overhead, especially once it gets wet.
2. Power vs weight. To lift a 2000 pound mass against gravity at the Earth's surface at a reasonable speed, say 100 mph, requires 533 hp. So each 2000 mass of the climber must include a 533 hp motor and a PV power source and electronics large enough to provide the required electric power. Not to mention the structure to hold that 2000 pounds together and the drive system to deliver that power to the interface with the tether. Or course, as the climber ascends the tether, the gravitational force is reduced, but so too is the distance over which the laser drive must pass and there will be distortions going thru the atmosphere. I doubt there would be much payload available, once the mass of the drive system is calculated.
3. As the climber ascends, there must be a transfer of energy to the climber to increase it's tangential velocity. That acceleration will the result of the force from the lateral offset of the tether toward the West, as the climber lags behind the launch site due to the rotation of the Earth. If the climber maintains a steady rate of ascent, upon attaining GEO, the climber will be some distance behind the launch site with the tether at an angle to the vertical. There will still be a force on the tether, which will accelerate the climber toward the East and as the climber passes over the launch site, it will have a greater velocity than the desired tangential velocity. Thus, the climber will continue toward the East, with the force due to the tether now retarding that motion. At some point, the climber will lose enough velocity that it begins to move back toward the West. There's no way to damp the resulting oscillation without thrusters, IMHO.
3. Then there's the problem of building the tether, layer upon layer, since attempting to deploy the tether in one operation would require a single launch of hundreds of tons mass to GEO. Adding each layer of thin material requires bonding the layers chemically, which then requires evenly tensioning both the tether and the added layer under controlled conditions for a period of time long enough for the bond to reach maximum strength. For example, at a climb rate of 100 mph, a 10 second bond time would require a mechanism capable of containing 1470 feet of tether within the controlled environment. The process must be executed perfectly all the way to the balance mass, which might be located at twice GEO or 50,000 miles above the surface.
4. A heavy climber must grip the tether between some sort of wheels or rollers. The grip is a function of the friction between the tether surface and the wheels, which may be reduced as each pass tends to polish the surface. How fast will the tether wear with each pass and how will it be repaired?
E. Swanson
And yet... they persist!
_________________
I saw an open-source technique for making robot parts. Alternate layers of aluminum foil and polypropylene film or non-woven cloth are stacked, compressed lightly, and heated with an induction hotplate. The foil heats, the film/cloth melts, and the result is a stiff, strong composite material. (The rest of the technique has the foil and film cut on cutting plotters, like vinyl cutters, loading inserts like bearings or nuts into pre-cut holes, facing with texture molds if used, draping over a mandrel, compressing, and then heating. This allows making complex parts without owning a machine shop.)
The tether components could be lofted in several groups and then stacked and bonded as they issue past rollers at deployment.
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You might enjoy reading biographies of Werner Von Braun. I found this one, "Dr. Space: the life of Wernher von Braun" in a used book store. He was the American space program.
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http://www.astronautix.com/lvs/skylon.htm
http://en.wikipedia.org/wiki/Skylon_%28spacecraft%29
SKYLON Spaceplane: Mission Animation:
http://www.youtube.com/watch?v=3bkjiGGy0gc
Skylon space plane gets a thumbs-up (images):
http://news.cnet.com/2300-11386_3-10007900.html
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Having fun:
JAXA RVT
http://www.youtube.com/watch?v=-irOfrXy4N4
MKV! With bang-bang servo:
http://www.youtube.com/watch?v=KBMU6l6GsdM
Japanese DACS with linear servo:
http://www.youtube.com/watch?v=63gqPvWbkMg
Rocket V.S. Rocket used to be considered impossible...
Like hitting a bullet with a bullet. Forged round:
http://www.youtube.com/watch?v=OAaw3S56nhc
http://www.youtube.com/watch?v=c5dIaDGUfLI
I am not an advocate of space elevators for the earth (the moon is a different problems).
I am fairly sure that a nanotube cable would be more conductive than copper so lightening shouldn't be a problem
Re powering the thing, the only way that makes any sense is to use a loop of cable and power it from the ends, Coriolis effect keeps the strands well separated.
Traffic of 100 t/h takes 1.5 GW of power. I suggest 1000 mph so you can get to GEO in less than a day. 25 ton loads 4 times an hour.
With a steady stream of loads coming up, the cable will lean to the west (minutely slowing the earth's rotation) and stay there. The loads would be taken off at GEO where they would be turned into power satellites.
The elevator would have a station at 50 miles where the loads coming up the acceleration cable would transfer to the main cable.
It's possible to have a constant diameter cable that effectively tapers by going through pulley systems. Thus the whole cable could be inspected and patched on the ground
There is still the problem that all satellites crash into the cable eventually. A big ablation laser will clean out the space junk and I suppose the rest could dodge at the cost of station keeping fuel.
Even if we never build them they are useful to compare other methods of getting to GEO since they are ~100% efficient in turning electrical power into energy of position.
Such shuck and jive as not to be believed.
The tether design is a ribbon, such that the rollers/wheels can grip it, just like a tire against the flat asphalt on a road. At the surface, the tether is in tension, a tension which increases all the away to GEO (and beyond) as the tether at GEO must support the weight of the entire tether down to the Earth plus the tension at the surface. Thus, it's likely that the tether would be tapered, with the thickest section at GEO where the stresses are greatest. One consequence of the tether system is that the maximum mass which can be lifted is limited to the tension at the surface. Only one such mass can be moved along the tether at any one time, since no more lift capability is possible, once the added weight of that climber is subtracted from the total tension below.
1.5 Gw of power for a drive system? Are you serious about that? Have you thought about how difficult it would be to build a laser drive, combined with PV conversion to electricity used to power the drive motors? The laser driver would need to be perhaps 4X larger than the drive motors. Worse, with a PV system, the energy from the laser drive which is not captured to electricity must be dissipated to space with radiators, which reduces the payload yet again.
And yet you cheerily suggest this is at all possible...
EDIT: Of course, as the climber rises, it's downward force on the tether is reduced as both it's distance from the Earth increases and it's tangential velocity increases, yet, the maximum lift loading can't be repeated until the climber reaches orbital velocity at GEO.
E. Swanson
Obviously to maximize the total mass carried to GEO each individual load would be much less than the maximum possible load so that several could be on the elevator at once.
Apart from that I agree the elevator to GEO isn't high on the list of possible systems for getting into space.
That's what it takes. 15 kWh/kg x 100 t per hour.
No, no, it's an electric drive motor on the surface. 900 RPM and a 31 foot diameter drive wheel for 1000 mph.
The payloads are just clamped to the fast moving loop of cable and up they go (takes an acceleration secondary cable up to ~80 km.)
Takes better than 63 GPa cable to use a constant area cable loop. But you can have pulley way stations that let the size of the cable increase.
And I don't "suggest this is at all possible." Even if you had the cable, the problem of satellites hitting the cable is not solved.
Here's another show stopper for yah. Last time I looked, no one had been able to build a tether which was strong enough to hold up it's own mass at GEO.
http://en.wikipedia.org/wiki/Space_elevator#Cable
Add this one to your cable loop design problem. At the top of the loop, the cable must bend around some sort of pulley. As the Earth rotates each day, the loop will twice be exposed to the direct rays of the sun and twice to deep space with no heating. A composite loop after facing the extreme cold of deep space may experience very cold temperatures and may be too stiff to bend around the top pulley...
E. Swanson
Graphene is a candidate material for a geosynchronous skyhook cable.
Don't take anything from Wikipedia as gospel; the claim in the article about the required "characteristic length" is not accurate, and you'll note that it's not supported by a citation giving actual calculations.
You might want to edit the wikipedia article.
If you don't have to time to make it perfect, just improve it by noting disagreement or deleting the incorrect material.
Well, perhaps the Wikipedia reference wasn't so great, but I gather you have no better reference to point to. Be that as it may, finding the right material is only one of the problems. There are others, many of which I have mentioned, which preclude the space elevator from becoming reality.
Keith's segway to a looped belt system is even less likely to work than the single ribbon cable, since neither can be installed in one launch and must be built up over some period of time. That's because the mass of the completed tether and 2 reels plus the rest of the deployment system is so large that it can not be launched to GEO with any vehicle likely to be available. The balance mass must be quite large and it must be placed a considerable distance beyond GEO. The loop cable can not be tapered and will at least double the tension force at GEO, compared to a single tapered ribbon, which would then require that size of the balance mass be similarly doubled...
E. Swanson
That's not the case if you allow step tapers.
If you go to slide 47 here:
www.nss.org/settlement/ssp/library/CO2andSpaceResources.ppt
You can see how to do a continuous, constant diameter, step tapered cable. It's a tall picture so mess with the browser bar to see the top and bottom.
I couldn't describe it, I couldn't even sketch it, so I had to make a model.
The orange electric cord was just to keep the rollers separated while I strung the rope through it. I should have removed it.
If someone were to actually *do* this, they would rig the whole thing in space at GEO and start extending it both ways, inserting the pulleys as they went. The total length came out to be around 100 times the distance to GEO and the initial thread was almost too small to see. Charge the cable so electrostatic repulsion would separate the strands, once it is moving the strands stay separated by Coriolis effect.
Once the earth end touched down, the thread would be cut and a new and heavier thread attached. *If* the design speed was such that a trip to GEO was a day, then the stronger cable would come back to the earth end in 100 days, whereupon you attach the next heavier thread. Starting with 100 kg/day to GEO, and going to 100 tons per day is a factor of 1000 which is close enough to ten doublings. 100 days x 10 is 1000 days or around 3 years to build from a thread to something useful. And other than the initial thread, all the cable and power comes up from the earth end, 99.9% of it.
Of course it would take longer because you would have to be lifting stronger pulley segments and stopping the cable to insert them.
There might be ways to save this thing from a cut cable since there are multiple strands, but the whole thing has considerable inertia so it might not be possible.
You don't have to tell me there are a lot of problems with this concept. Like it needs real time adjustment of all the pulley diameters to keep them in place.
But it served the purpose of getting me to looking for unconventional ways to get enough cargo to GEO to build a meaningful number of power satellites.
All of the "Forget it, kid." responses remind me so much of the movie "October Sky"
Trailer:
http://www.youtube.com/watch?v=qHyWE7s_lGA
The amount of naivete and desperation to grasp at this straw is amazing.
Only exceeded by the amount of smoke and mirrors and hand waving.
The Cold Fusion believers have more than met their match.
One last time: Sell the idea to the Chinese...if they can't/won't do it, then it ain't getting done.