Improving the Performance of Solar Thermal Power

The US Department of Energy granted a US$1.37 billion loan guarantee to Brightsource Energy last week which could help clear the way for over 15 gigawatts of solar thermal power projects in California. Brightsource built a pilot plant in Israel to prove their technology and has tested it over the past 18 months. Their flagship Ivanpah project in California got a big boost when construction giant Bechtel agreed to build the plant.

Solar thermal is a way of harnessing the largest source of energy available to us, so in this post I'll have a look at the upswing in interest in the use of this technology for power generation in recent years and look at some of the approaches being pursued to make it economically competitive with coal fired power generation.

Photo credit:
One-time Australian solar thermal company Ausra was the leader in terms of publicity a couple of years ago when I last covered this topic, but the company seems to have slipped off the pace, failing to build a large scale facility and recently being purchased by French energy company Areva.

Interest continues to bubble away in solar thermal power in Australia, with energy policy advocacy group "Beyond Zero Emissions" launching their "T10" campaign to switch Australia to 100% renewable power in a decade, largely using solar thermal power, and the Desertec Asia proposal also featuring concentrating solar power (CSP) heavily. At one point Prime Minster Kevin Rudd was promising to build the world's largest CSP plant here but that idea hasn't had any media airtime lately - and neither has Worley Parsons' proposal to build a large scale plant in north west WA. The most active plans to build a local CSP plant seem to be coming out of ERM Power, who are proposing gas / solar hybrid plants to be built in Queensland and/or NSW in conjunction with Siemens.

The company making the most waves from a technology point of view lately is Californian company eSolar, founded by IdeaLab's Bill Gross. eSolar has been in the news lately as a result of their partnership to construct turnkey CSP systems with German company Ferrostaal in Spain, the United Arab Emirates and South Africa. eSolar has also received attention for Chinese plans to build 2000 MW of combined solar/biomass facilities using their technology.

Gross was recently interviewed for Yale Environment 360 and outlined his vision for improving the performance of solar thermal power generation, with some of his key points being :

* Use software to analyse and optimise performance of plants

The biggest lesson that we brought was — I don’t know if it was a lesson, but it was a philosophy — which is Internet-enable everything and put monitoring into everything. So we have a microprocessor in every mirror and we have statistics second-by-second on the status, position, reliability, pointing accuracy — everything — of every single mirror. We structured ourselves almost like an Internet company from the beginning to have logs of everything — every revolution of the turbine, every control from the control room, every Web cam image captured — so we could do data mining and data analysis on everything. We want the ability to make software upgrades and impact every power plant around the world. That’s probably one of the biggest differences between our technology and all other solar technology. If you [have] a big field of [photovoltaic] panels, those PV panels are there for 25 years. They’ll have that same performance, and there’s nothing you can do to change that. We can make a software upgrade and every power plant in the world can suddenly put out 3 percent more power potentially. And we found already a number of software improvements that we can make even over the past six months, which significantly boosts performance of an already-constructed power plant. There’s new improvements we can make to the actual hardware, too, but even without changing the hardware there are software changes that can make more power, so we’re really excited about that.
* Don't build plants, get utilities (customers) to.

For renewable energy, about 80 percent, maybe 90 percent, of the cost is upfront and there’s no fuel costs and the only cost over the years is operation and maintenance, which is small. The biggest bottleneck is that these things cost big dollars, and you’re limited how fast you can grow by how much money you can raise to build plants. Our particular strategy to deal with that is to not have us be the bottleneck for raising that money. Our customers raise that money. If we want to renewably power this planet, it’s going to take a lot of capital, and that capital has to be spent upfront.
* Avoid environmental conflicts and transmission line costs by building smaller plants on brownfield sites near cities.

We have a strategy at eSolar to never impact pristine land. And the way we address that is several-fold. First, we have a higher output per acre, so we take a smaller footprint. Second, we’re economical at a smaller size. We can be fully economical at our 46-megawatt size. Those two things combined let us use a small enough footprint that we can locate on private land closer to population centers. So rather than needing 2,000 acres contiguous to make the economics work — which you almost only can find far away on pristine land or [federal] land — we can locate on only 200 acres very close to a city and we can buy previously disturbed farmland or other properties that’s already been developed so we’re not causing any disturbance to natural habitat. And that’s an important part of our philosophy. It gives us an economic advantage because we’re locating closer to transmission. That’s probably even a bigger factor. It takes years and years to build the transmission out to the pristine lands. [But] the power plant, for example, in Lancaster [California], is across the street from a transmission line. We didn’t have to build miles and miles of transmission, which takes years and years to get people to approve.
* Leverage energy storage and volume of scale in manufacturing to reduce costs.

I feel we still need to get almost another factor of two in the reduction of energy costs to potentially compete with coal. We’re already close to competing with natural gas. It depends on the sunshine and the region. Another factor of two is going to require two things to make that happen: Approximately 25 percent of that can be gotten by adding [energy] storage, and 25 percent can be gotten by increasing efficiency and lowering costs by volume production. We produced 500 mirrors two years ago, 24,000 last year, and this year we’ll produce a million. So we’re going to get a quantity break just by going to a million mirrors from 24,000. And everything gets more efficient in the supply chains as you get up to those volumes. Anything that we buy in our lives that has dramatic cost reduction has seen a million — a million cars, or a million iPhones, or a million laptops. So far there’s only been thousands of heliostats. So finally this year we’ll cross the million number and that’s when we can get the price reduction to really be competitive with fossil fuels.
Google recently announced they have developed a prototype for a new mirror technology that could cut by half the cost of building a solar thermal plant, with both eSolar and BrightSource expressing interest in using the technology.

Previously at The Oil Drum :

Concentrating On The Important Things - Solar Thermal Power

Concentrating Solar Power

Cross posted from Peak Energy.

New World Record Set For Solar Efficiency: 31.25%

The solar thermal power industry is growing rapidly with 1.2 GW under construction as of April 2009 and another 13.9 GW announced globally through 2014. Spain is the epicenter of solar thermal power development with 22 projects for 1,037 MW under construction, all of which are projected to come online by the end of 2010. In the United States, 5,600 MW of solar thermal power projects have been announced.

Source: Wikipedia, List of solar thermal power stations

Improving the performance of combined cycles with solar thermal energy


Dragos Parausanu-Sprinceana

Two times zero is still zero! I'm sure 5600 MW will make a HUUUUUGE dent in our thermal energy usage, no?

"The greatest shortcoming of the human race is our inability to understand the exponential function." -- Albert Bartlett

The greatest shortcoming of solar energy is its inability to expand exponentially!

The greatest shortcoming of modern man is believing BAU will continue.

Wow, is that world capacity? 'Cause speaking of "concentrating solar power," this one is just the U.S.:

How many trees (nature's "solar collectors") had to die, I wonder, for all those solar panels to be installed?

You're pushing Biomass, but are concerned that Solar is costing us Trees?

A great amount of Solar can be installed on existing structures, and as the article stated, can reclaim disused Brownfield sites, etc..

Thanks for continuing to respond sensibly to this stuff - its just an endless stream of red herrings being trotted out.

The post does note the Chinese are pursuing a combined solar / biomass strategy (while many in the middle east build combined solar / gas plants) - but the obvious drawback with biomass is that it only scales so far before you start chopping down anything that grows to feed the machine - just as bad an idea as large scale biofuel production.

The great thing about solar is that you can put CSP on brownfield sites or PV on rooftops - or you can go out into the desert and build huge facilities - it scales really well (across a range of technologies).

Thanks, Gav.

It seems so obvious to me, I'm just kinda baffled when someone kicks in with such a roundhouse objection to anything solar.

Wasted Energy's 'Wannabe' post that he linked to somewhere here seems to show a strong distaste for anything that would be popular with environmentalists.. if you totally resent Hippies still, it's a little tough to embrace Solar, I think. They never owned much, but they still own that.

Yeah - that could explain it :-)

Speaking of hippies, they are (part of) the topic of today's post...

Every time I see a chart or table of wind or solar capacity installation I immediately wonder if the numbers are for nameplate and what is the real average output.

My guess above is that those are nameplate numbers and that the real average output is a third or less. If so, then solar maybe added the equivalent of 5 nukes in 2008.

It is worth noting that 1 GW of nameplate capacity in Germany will produce far less than 1 GW of nameplate in Arizona.

The capacity factor only scales the exponential, is does not change the fact that it is a rising exponential. Given enough time a rising exponential will overwhelm other factors.

Of course it can -- far more simply than many technologies, since the fab and installation industries are already vast, compared to nukes for example.

Amazing that higher-latitude countries with less sun have the most extensive solar installations!
Hmm it's probably to do with the available money supply, not the sunshine supply...
I'm eagerly awaiting hybrid Solar-Geothermal power here in Oz, so that we can tell people that the sun shines out of our borehole!

Not just the most extensive, but also the most expensive!

As a resident of the tropics I have often pondered theses facts myself as I swelter under the heat of my concrete slab roof (currently 30.1C/86.2F at 12:30 p.m., well on target to beat yesterdays peak of 33.1C/91.6F at 6:30 p.m.). I am not aware of any research going on in my neck of the woods surrounding putting this abundant source of energy to good use. Around here LPG is used to produce heat for industrial and commercial needs. The local cement plant uses coal to fire it's kilns. The power company uses "bunker c" fuel oil to run it's steam plants and gas for it's combined cycle and other gas turbines. A local glass recycling plant and steel recycling plant went out of business a couple decades ago when rising energy costs made them uncompetitive with plastic bottles and imported steel. Why?

I guess the answer is that all the available industrial equipment is built up north in the lands where exploiting cheap FF has been the status quo since the dawn of the industrial revolution. I guess a solar revolution is in order but, as long as cheap FF is available there's no incentive to do it. As often pointed out on this site, after the cheap FF is gone, there probably will not be enough money(energy) to build the required solar infrastructure. Again, I am inclined to point my accusing finger at the agencies that should be telling the world that future FF prices are likely to be a lot higher, well within the lifetime of all the proposed renewable projects, making them all cheaper than FF powered options in the long run.

An interesting case is my own island nation. The power company's installed capacity is getting really long in the tooth and much of it will be up for replacement soon. There is also the matter of demand growth, which I question since current rates are already too expensive for many customers (two 0f my neighbors have had their supply cut off, in one case since December and the other since last month). The big debate is whether the new capacity should be coal fired or NG with at least on newspaper column saying that renewables will be too expensive. Fortunately the only announcements I have heard recently are for 10MW of renewables which would constitute approximately 1% of peak demand. I keep sending links to stories on CSP and Peak Oil to a contact I have who has close ties to the minister of energy, in the hope that such information might stymie any attempts to acquire any large scale FF powered electricity generating plants. it is my considered opinion that rising energy prices and reduced supply will hit countries like mine very hard. Why do I stay here? For now i would rather be where solar energy is abundant all year round, than where it is scarce in winter.

Alan from the islands

"Hmm it's probably to do with the available money supply, not the sunshine supply..."

With the continuing credit unwind, the rise of sovereign debt, and the proliferation of PIGS, it will be interesting to see where all this phantasmal funding is going to come from. BAU is dying get over it and move on..

I dunno, I think solar "energy" might be just a tad overrated:

That's a really confused polemic promoting bio-fuels. It makes several starts to criticise solar-thermal generation and then immediately reverts to reasoning against PV. What the heck does the availability of arsenic and galium have to do with solar thermal? And it's inuendo that solar thermal generation produces electricity "5 to 6 times more expensive" than fossil is simply flat wrong. Present costs are in the range of 12.5 cents / kwh, and that would be very competitive with gas if it were reduced by perhaps 50% to 100%. Sargent and Lundys Engineering of Chicago contracted a study for NREL recently which concluded that after the world builds "2.8 GW of solar thermal", volume efficiencies and technical improvements will make it competitive with gas peakers. Get to 12 GW, and it will compete with coal.

I'm a big proponent of solar (since I live on it), yet how can solar compete with the 24/7 production of fossil fuels? Until the storage problems are worked out, it can only augment these other sources and offset peak demand. Economies don't play well with intermitancy.

The storage "problems" are already worked out technically and economically. Simply using excess collectors to heat up large insulated boxes of sand and gravel work very well and is cheap, according to NREL scientists.

Only real issue with storage now is that installing it makes NO SENSE as long as the utility is still running any Nat. Gas peakers, since all of solar thermal's normal generation happens in peak hours when electricity is most expensive.

Utilities are a) very conservative and b) worried about loosing money on their investments in esisting generating stations.

Such a statement is completely absurd. The Andasol 1 molten salt storage CSP plant in southern Spain has a capacity factor of 40.7% even with storage-- meaning it doesn't work 59.3% of the time. Molten salt storage does nothing to ameliorate seasonal fluctuations or long expanses of clouds. It just allows diminishing power production several hours into the night in spring and summer, a far cry from baseload. Furthermore, this is the thirstiest of all energy sources, and the most expensive. It costs 58 cents per kilowatt hour compared to coal or nuclear at 2 cents. The mirrored arrays need to be washed down every 5 days-- and water is scarce in the desert. This is just a red herring; a chimera. It will never provide even 1 percent of our energy. All the solar capacity in the world is just 13.4 gigawatts-- equal to just one coal or nuclear plant, since the capacity factor is so low. The U.S. gets 0.02% of its electricity from solar even after decades of promises and subsidies. We also can't make the construction materials without fossil fuels, and if we tried to store it using lead-acid batteries or compressed air it wouldn't even yield net-energy, like ethanol, the EROEI is so low. Storage kills EROEI since it lowers efficiency and requires even more construction. Even without storage, the energy return is negative if desalination of seawater is used to wash off those mirrored arrays every 5 days and truck the water into the desert so they don't cloud out. Look at how much power those hydro dams generate; moving water is hugely energy intensive. Like ethanol, this is a scam that will just compound our fossil fuel problems, engaged in at our own peril as the peak oil and global warming clocks rapidly run down.

So the obvious question is, if CSP is a scam and PV is too expensive and wind is too intermittent, what are we going to do? Personally I've got enough PV to take care of my less than 120kWh per month electricity consumption but what about all those (most) people, especially Yanks, who don't have any PV or wind power and can't afford to buy any but, would shudder at the thought of using less than 600kWh per month (for a 4 person household)? This is going to be very interesting!

Alan from the islands

What are we going to do? That's what they asked Howard Hayden after he wrote "the solar fraud." His response: "Know nukes."

There is an interesting post starting out today's drum beat which talks about how solar is good for "low entergy" tasks like heating pool water or cooking food. It can also be used passively for light and drying clothing. However, it just can't produce electricity. According to Scientific American's January 2008 "The Solar Grand Plan," it would take 30,000 square miles of CSP to provide just 35% of U.S. energy in 2050. To do this we would need to cover two square miles a day for 40 years-- all the solar panels in the world a week. That's just ridiculous, and the cost, storage, water, and EROEI problems are each individually insurmountable, let alone a perfect storm of all four.

"However, [solar] just can't produce electricity."

Sorry, it powers my net-metered house, taking up on roof space. Like Island Boy, I use far less than the typical US house. Passive solar also provides about 40% of my space heat. It's that simple...

What happens at night? What happens in the parts of the U.S. that don't get much sun?

""What happens at night?""

It gets dark you moron, and then all the morons should be in bed....

Sorry to be so harsh, but as a woman on this site for a short time, reader for years, I am truly amazed at the level of incapacity in men. Grow up. Life is changing and your Momma of FREE ENERGY, ain't around to wipe your butt anymore.

Learn to live with the flows of Nature. Because you really have no choice.

You tell him, Drifter. (Him? Probably)

He's only from the 'Sunshine State', after all.

It just made me wonder, has anybody ever seen a PV powered Tanning Salon? That would be the most absurd thing I could imagine, but I think Arizona or Callie would beat FLA to the punch.

Exactly. In a post peak world, few of us will live life by the clock. We'll live by the sun and the weather.

Hey Drifter, some of us aren't old, and like to stay up and party at night sometimes!

I believe the best way of "keeping the lights on" at night is the same way it always was: campfires! Of course, this time, we might just be able to upgrade to biomass power plants...assuming fools don't steal all the best power plant materials to build solar towers!

They use wind power. Wind is, on average, a little stronger at night, and in the winter. A nice synergy with solar.

Yes, wind has some intermittency, but that's exaggerated.

Geographical diversity, a bit of long-distance transmission, a little storage, a few milllion EVs charging when wind is strong, and supplying power when it slows down, a little FF backup for the rare times when all the wind and solar output is low for an extended period, and you're good.

There is less demand and we use a combination of wind, wave, hydro and nuclear power. Is this so ridiculous?

Hey Will, guess who paid for your solar-powered house? That's right, WE ALL DID!!!

Wrong yet again, this was before the current subsidies (1999). If you want to refund my costs, I can arrange that.

All I got was a sales tax exemption from the state of Arizona for my off-grid PV system. I even bought PV panels back in 1990 when they cost about $10 / (rated watt) with no incentives. Now I can buy them for $2.69 / (rated watt) and still get only a sales tax exemption.

"However, it just can't produce electricity."

Ha! Every time some bozo makes this comment my mind screams "Stupid f'n idiots!" Ten's of thousands of people have been proving this as false for years now, yet the lies persist. The truth of it is that folks like you can't conceive of a lower energy lifestyle, and have no clue how easy it is. You are so invested in the habits of consumption and convenience that you ignore a reality that already exists. WE CAN LIVE WELL ON MUCH LESS ENERGY AND I AM PROOF.

It amazes me how people can change their lifestyles, their habits. They'll do it for a job. They'll do it for a mate. They'll do it to look better or feel better. They'll do it for social gain. But they can't seem to do it if it involves forming habits like consuming less stuff, thinking before they drive, making responsible purchases, or simply turning things off.

The long term costs of nuclear are enormous, and the price of not bearing those costs is unthinkable. Until you can convince me that we are not kicking the dirtiest, nastiest can down the road to our grandchildren, I can't support it. We need to teach our children to make more responsible choices or we are truly doomed.

Solar will never be a panacea. It's just part of a more sustainable mindset.

Rant off. Sorry!

Keep going, I'm loving the rants today.

I'm sick of those tired complaints on PV, too.
It's 'upside the head' time. I'm ready..

"It's 'upside the head' time. I'm ready.."

Sounds kuhl to me, jo!

Speaking of dolts, I'm tired of people promoting "PeeVee and "Ee-Vees" at the expense of Waste to Energy!

WAKE UP PEOPLE AND LOOK AT LIFE AROUND YOU. Do you really want to pay 65 cents per KWH? I know I don't, even if my electric bill this month was only $11 (who can beat that?)

Pro Tip: High capital costs usually mean LOW net energy! And you have to count them subsidies too!

I'm using solar and I don't pay 65 cents per kWh. Where on earth do you get your numbers??

"High capital costs usually mean LOW net energy"

Absurd, wind and solar both have fairly quick energy paybacks.

And every rooftop could have solar PV; rooftops without have zero net energy, the greatest wasted energy of all...

Although you are absolutely correct that most people living in North America can live on a lot less energy and material goods while maintaining a good quality of life, if everyone did that the economy would collapse. Even with no peak oil and no financial crisis, if everyone in North America stepped off the consumption treadmill and started living more sustainably, the economy would fail for lack of exponentially growing consumer spending.

Just a thought.

"the economy would fail for lack of exponentially growing consumer spending."

Look around. The economy is failing, though I have no doubt that we'll keep spending. And the idea that so many of us make our living off of pure consumption matters little, because we're running out of stuff. Better learn to live on less. You'll be ahead of the curve if you start now. Spend wisely!


I wasn't suggesting that consuming more stuff is the answer to our problems. I was describing a situation where the financial system was working (or appearing to work) normally and oil was plentiful and people simply stopped spending. I know the economy is failing.

People in North America are probably going to find themselves living with a lot less fossil fuel energy even if we are still producing roughly as much oil in 40 years time as we do today...

I don't know. It looks like the US has a lot of cheap coal, and a lot of medium expensive gas.

I think we're going to have to choose to end FFs that quickly, not have geology do it for us.

Really? Link please.

Ok. I assume you're really asking about coal, given that gas has been dealt with pretty thoroughly on TOD lately.

One could ask several questions related to coal.

First, why ask the question? Don't we want to reduce or eliminate coal because of climate change?

Yes, we do. For better or worse, however, it's important to be realistic about the availability of coal. If we're not running out of it, we have to make a conscious decision to eliminate it, not rely on geological limits. Also, it's good to know whether or not we'll face energy shortages due to coal scarcity. If not, we have more options - if we face an emergency, we will have the option of using coal. Of course, that may be expensive and difficult to do without excessive CO2, but options are usually good to have. In that vein, we should note that if we have coal to spare it's actually easier to sequester CO2 - sequestration consumes a fair amount of energy, and if things are tight it will be much harder to pay for something whose necessity isn't obvious to all .

So, do we face limits on our coal production, as a practical matter?

No. Coal is unlike oil - we have enormous reserves, we know exactly where they are, and there is no significant increasing marginal cost to their extraction, except for temporary costs of expansion.

Do higher energy prices raise the costs of extracting fossil fuels?

It depends on the individual case. Coal has a high E-ROI. For instance from a recent survey by Heinberg ( from ): "Consider the case of Massey Energy Company, the nation’s fourth-largest coal company, which annually produces 40 million tons of coal using about 40 million gallons of diesel fuel—about a gallon per ton" .

That's a very high E-ROI: a gallon of diesel is about 140K BTU's, and a ton of coal is very roughly 20M (see ), so that's an E-ROI about 140:1! Now, diesel costs very roughly 10x as much per BTU (reflecting it's scarcity premium), so the cost ratio isn't quite as favorable, but it's still well above 10:1. So, the price of diesel rises by $1 (roughly 25%), and the cost of coal rises by $1, or very, very roughly 2% - not a big deal. Also, we should note that coal mining (and transportation) is often electric even now (especially underground), and that it's pretty amenable to further electrification - in other words, coal mining can power itself using a small fraction of it's production.

Will higher coal prices make a substantially larger fraction of the coal available for extraction?

Yes, but only slightly higher prices are needed. Here's what Heinberg has to say: "if Montana and Illinois can resolve their production blockages, or the nation becomes so desperate for energy supplies that environmental concerns are simply swept away, then the peak will come somewhat later, while the decline will be longer, slower, and probably far dirtier.". The Montana "production blockages" he talks about are relatively trivial, and Illinois doesn't really have them. The pollution he refers to is CO2 and sulfur - the sulfur costs about 2 cents/KWH to scrub, and the CO2 might cost out at $80/ton of CO2, which IIRC would add about $30/ton of coal, should we choose to internalize this cost.

Illinois coal simply couldn't compete with Powder River coal with a 2 cent premium for sulfur scrubbing - it's as simple as that. UK and German coal became a bit more expensive, and they couldn't compete with cheap oil.

The same general rule applies to US, UK and European coal: only under Business As Usual is coal declining - people who say otherwise are misinterpreting the data. I discussed this at length with one the often-quoted authors on this subject, David Rutledge, and we came reasonably close to some kind of agreement on this. If there are serious energy shortages, the old reserve numbers will apply, for better or worse.

So, would a doubling in coal prices substantially increase recoverable coal reserves?

Yes. Now, "recoverable" is tricky: the normal distinction used by the USGS is "economically recoverable" - that includes economic assumptions, and Illinois coal (and much other coal in the world), at a slightly higher cost as discussed above, is currently uneconomic. But, that's under Business As Usual - if we have a true energy scarcity, Illinois coal will very, very quickly become economic.

What about the "Law of Receding Horizons"?

That applies only to low E-ROI sources of energy. Coal is high E-ROI, unlike Canadian bitumen (tar sands) or Colorado kerogen (oil shale). I would note that the importance of this "law" has been enormously exaggerated, as it's confused with temporary capex issues and scarcity premia, which are allocating temporarily scarce capital resources.

More coal gets extracted from the ground each year as measured in tons, but hasn't the quality declined so much that net energy content is lower now than 10 years ago?

Powder River coal is lower energy density (sub-bituminous), but it's sufficiently cheaper to mine that the difference doesn't matter. Again, this is a purely economic shift from Illinois coal, which is higher energy density (bituminous). This shift has caused endless confusion to analysts unfamiliar with the coal industry (OTOH, people inside the industry understand this).

Aren't coal prices rising?

This is due to the temporary costs of expansion. Oil & gas are much more expensive per BTU due to a scarcity premium, and so demand has increased for coal. Most coal is on long-term contract, not on the higher spot market (unlike oil). But it's important to be clear that the long-term marginal cost of extraction isn't increasing, as it is for oil.

Mmm, my question was more about the word "lot", as in "a lot of cheap coal" and "a lot of medium expensive gas". As I understand it, coal may be fairly near (as in a decade or so) to peak, in the US, at least in terms of energy content. Maybe the poorer quality stuff is cheap and maybe it's more abundant but a larger quantity is needed, and it's dirty. Heinberg has a recent book on coal, though I haven't read it yet.

As for gas, I see that the monthly dry gas production estimates from the EIA appear to show a stagnating (if not slightly trending down) supply since the last peak in March 2009, following a fairly long rise against earlier trends.

As I understand it, coal may be fairly near (as in a decade or so) to peak,

Yes, that's addressed above - we have many decades of coal. Here's more info:

A new report by the US Geological Survey looks at the recoverable reserves of the Gilette field in Wyoming, currently the largest producer in the US.

It found that at current low prices, about $10/ton, that only about 6% of the coal in the field could be economically produced.

On the other hand, if the minemouth cost of coal rose to $30/ton, the retail cost of coal-fired electricity would increase only 10%*, but economically-recoverable coal reserves would increase six times. At $60/ton, 77 billion tons would become economic, enough to singlehandedly maintain US coal consumption for about 75 years. And, that's without Montana coal (Powder River), or the Illinois basin, which I discussed previously.

Will Peak Oil make diesel too expensive to transport coal?


A $100/bbl increase in the cost of oil would increase the cost of transporting a ton of coal by $100/bbl x 1bbl/42 gal x 2 gal/ton** = $4.8/ton. That's a 2.5% increase in the cost of electricity, which means that railroads will be easily be able to out-bid other potential users, like trucks.

Coal transportation by rail can also be converted in a relatively straightforward manner to use electricity instead of diesel, meaning that reduced oil supplies are highly unlikely to have a significant direct impact on the ability of the US to transport coal.
We're going to have to make a conscious decision to eliminate coal - it's not going to run out, and make the decision for us.

A spirited discusion of the report can be found here (you'll have to watch out for the tone of pessimism, which is endemic on the site).

What about this report?

"Despite significant uncertainties in existing reserve estimates, it is clear that there is sufficient coal at current rates of production to meet anticipated needs through 2030. Further into the future, there is probably sufficient coal to meet the nation’s needs for more than 100 years at current rates of consumption. However, it is not possible to confirm the often-quoted assertion that there is a sufficient supply of coal for the next 250 years. A combination of increased rates of production with more detailed reserve analyses that take into account location, quality, recoverability, and transportation issues may substantially reduce the number of years of supply." From Coal: Research and Development to Support National Energy Policy

There's no real disagreement here - what disagreement there is, comes from a different frame of reference.

1st, they say "it is clear that there is sufficient coal at current rates of production to meet anticipated needs through 2030". I would argue that's probably all we need, for the transition to renewables.

2nd, they say "there is probably sufficient coal to meet the nation’s needs for more than 100 years at current rates of consumption". I would argue that's certainly all we need, for the transition to renewables (or fusion, for that matter - in 100 years things will be very different).

Finally, they say that there are risks beyond 100 years: the coal is there, but that 1) the US might dramatically increase it's rate of consumption - I think that's highly unlikely, 2) other issues may get in the way. Well, if we really were to face a situation where our economy's collapse could be prevented by digging up our national parks...the national parks wouldn't stop us.

All in all, I'd say that report supports my perspective: In the US, there's no realistic prospect of inadequate electricity caused by real, physical limitations.

*Electricity in the US is about $0.10/kWh, and US coal generates about 2,000kWh/ton. That gives a retail price of electricity of $200 per ton of coal used, so a cost of $10/ton for coal represents only 5% of the overall retail price.

**Rail transportation is about 440 ton-miles/gallon on average, and coal is at minimum 500 tm/gallon (Coal trains are probably even more fuel efficient, because the ratio of load to tare weight is greater than most other rail freight (particularly intermodal). 600 tm/g might be a good guess). Low-sulfur coal in the US travels roughly 1,000 miles before being used. Dividing these tells us that transporting US coal requires roughly 2 gal/ton.

Just think of all that coal north of the Brooks Range that would need a relatively short rail trip to an increasingly ice free port on NW Alaska coast. It could keep China pumping for a long time. When you start talking 100 years and new climate configuration and much, much, much more expensive oil a lot of stuff can happen. Right now Red Dog Mine stockpiles zinc and led concentrates indoors on the Chuchki Sea and ships them during the July-October season. With the arctic seas' freeze up occurring an average of three days later every year-this trend will eventually decline and stabilize as the arctic will freeze at some point every winter-the shipping season from a northern port could be much extended. Of course the volumes of coal that could/would be shipped would likely make indoor storage in that more than breezy region unlikely. Right now the relatively small stockpiles of coal shipped to Chile and Asia from the year round ice free rail terminus port of Seward are a contentious issues. I can't imagine how much coal dust would blow off the black mountains stockpiled in the northwest--especially if the economies have been weakened enough to cancel all environmental regulation in energy production related industry, but remain strong enough to keep extracting and shipping resources on gargantuan scale.

Of course it might be more profitable and cleaner to liquify and pipeline Alaska's wet coal in a couple directions--we are talking a 100 year in the future pipedream/nightmare here now.

From your 2nd link: Alaska has an estimated 5 trillion tons of undeveloped coal reserves

Good god, 5T tons?? That's a 5,000 year supply for the US. Could that be right?

Edit: A bit of searching at the Geophysical Institute, University of Alaska Fairbanks website that provided your 3rd link found this:

"A few years ago, estimates of Alaska's coal resources placed them at approximately 130 billion tons. Now, largely because of better knowledge about the coal beneath the North Slope and the offshore area beyond, the estimates range from 1,860 billion to 5,000 billion tons.

This, of course, is a huge energy resource if it could all be recovered for use. Full recovery is unlikely because much of the coal is deeply buried, of not the best quality or is at locations where transportation is lacking.

In estimating what portion of an identified coal resource is recoverable, experts considering reserves elsewhere in the United States pick figures ranging from one percent to over twenty percent. And that percentage generally is applied only to known resources, not those which are hypothesized to exist on the basis of surface outcrops or sparse drilling information. Nor does the percentage apply to resources speculated to exist, such as off Alaska's northern coast, on the basis of even less information. The 1,850 billion to 5,000 billion ton estimate for Alaska includes these hypothesized or speculated resources.

But suppose Alaska really does have a coal resource amounting to the lower figure, 1,850 billion tons, and suppose that 10% of it is recoverable. That means Alaska could recover 185 billion tons."

So, the 5T figure is an upper limit for resources, not a reserve figure. Of course, 185B tons is more than enough...

Thanks for parsing that out Nick, I only skimmed the first part of the second link and didn't see the 5 trillion number until you mentioned it. Obviously we are nowhere near out of coal if we have only done the most cursory cataloguing of a resource of that size. Lets hope we are doing a much better, cleaner job of it before we get to that chunk.

Lets see Seward negotiated the purchase of Alaska from Russia for $7.2 million or about 2 cents an acre back in 1867. That comes to about $110 million 2010 dollars (for comparison the state legislature just passed an $8.2 billion dollar operating budget this week). I wonder if the US will ever make out on that deal?

Really Russia didn't get a bad deal since they didn't really own Alaska, but that was the way of the colonial world.

That's talking about gross withdrawals. Dry gas production is a better figure to discuss, as it is much closer to the true amount of gas available to the gas producer's customers. Dry gas production is still below the peak of 1973, and hasn't increased for a year.

30'000 sq miles = 77,700 km^2 of CSP at 25% efficiency and 25% capacity factor corresponds to 5400 nuclear power plants (1 GW each).

Considering the fact that uranium mining cannot even cover 70% of the demand of all the 375 GW nuclear power plants, it's doubtful that enough uranium can be imported to power 5400 GW in the US alone.

Even the costly US military may not be able to force foreign uranium miners to produce that much uranium.

Building highly automated thinfilm PV factories will be the far cheaper option (producing silicon PV-modules at $0.7 per Watt compared to $8 per Watt for new nuclear) and create jobs in the entire country.

And PV doesn't depend on uranium imports, doesn't require any cooling water and can be placed on existing roofs. After all over 120,000 km^2 of the US is built already.

What are we going to do? We're going to stop using power for stupid things, like televisions, and start using our wood, not to mention metals, more wisely!

p.s. no really, for those who think solar energy can just run on sand alone, have you ever been able to generate electricity from a bowl of glass? I haven' least not yet...

Right now I can buy a 270W panel from $659, add a micro inverter from SWEA for about $250 (Americans can use Enphase for about the same) and for about $900 plus the cost of installation, I've got myself 250W of grid tied power! if I get nameplate capacity for the estimated average sun hours per day in my neck of the woods, I can generate electricity for about 7c per kWh. If I assume that these micro-inverters are junk and have to be replaced every 5 years, I'm still only at 14c per kWh. My latest electricity bill has me paying 26c per kWh for the first 100kWh and almost 36c for every kWh over that so if I'm offsetting the first 100kWh, my payback period is less than 6.5 years and if I'm offsetting yhe higher rate it's a little over 4.5! If it's on the "new inverter every five years" plan, the payback time doubles. No use telling me that PV can't work.

On the other hand we've got this strange problem of people setting fires at the local municipal dump here, whenever the largely unemployed strong arm men who live nearby are desperate for some cash. lots of old tires and other nasties make for some pretty spectacular smoke. Lots of equipment time and money need to be expended to put these fires out. I think it would be great if you could convince the Jamaican government that energy from trash is something that needs to be given priority. To be fair there is an invitation to tender for energy from waste at said municipal dump but (yawn) somebody wake me when anything happens on that front. At 26c per kWh for retail electricity, on the low end, it should be a cinch.

Alan from the islands

There's sort of a low hanging fruit principle where the grid can be used as a storage battery by selling low voltage power back into it. However, if everyone did this, it wouldn't work. Using lead acid batteries, it would be vastly more expensive and wouldn't even produce net energy.

How much energy do you think is required to manufacture a lead-acid battery from raw materials and recycled materials?

Table 1 in Impacts of EV Battery Production and Recycling (Linda Gaines and Margaret Singh, Argonne National Laboratory, Symposium Date: April 29 - 30, 1996) indicates:

energy to manufacture a 25 kW·hr lead-acid battery: 11.7 million BTU.
energy to recycle a 25 kW·hr lead-acid battery: 2.5 million BTU.

My off-grid PV system uses 8, 390 A·hr, 6 V batteries, storing a total energy of 18.7 kW·hr.

11.7 million BTU * (18.7 / 25) / 3413 BTU/kW·hr = 2,560 kW·hr to make my entire battery array.

My PV system has a rated power of 662 W and produces 3.0 kW·hr / (sunny day). Assuming cloudy days 75% of the time with no power output on cloudy days, the energy payback time for my entire battery array is 3 years and 42 days. If recycled batteries are used, the payback time would be a little over 8 months.

My last battery array lasted 14 years. One of my PV panels is 20 years old, 8 are 19 years old, one is 9 years old and the newest is less than 1 year old. None of my PV panels have failed yet.

Have you seen a similar life-cycle analysis for lithium-ion batteries?

Not yet, but according to Lithium-Ion Battery Recycling Issues (May 21, 2009) on page 4, Linda Gaines has that assessment scheduled for first quarter of 2010.

Well that has come a long way. Norris's description of the enless upstream loops indicates to me the system has been thought out thoroughly enough.

Interesting that the SA author mentions 'flooring of sustainable bamboo.' Bamboo flooring is very 'green in' right now, but hardwood forests are very sustainable. Just look at depictions of Massachusetts in the early 19th century and fly over it now--now it is 85% forest cover, very close to the inverse of what is was back then. Any bets on whether bamboo flooring or native hardwood flooring installed in the US gets the better LCA score? Third world labor has a lot to do with the 'green' of the former, in more ways than one. I wonder if any manufactured product from the west can compete when its share of the total chain supplying western life is brought in--just a thought. I can see an insidious angle to almost everything, I guess that ancient marketing ed back at the U affected my world view more than I'd like.

Ah, I found a source for the energy inputs for batteries. It turns out they're mighty small - small enough to show that those who worry about the additional energy needed to manufacture batteries for HEV/EREV/PHEVs don't need to worry any more.

109,700 joules per KM for Volt battery manufacture
44,500 for Prius

or in watt-hours:
Volt: 30.5
Prius: 12.4 page 17

That's much, much smaller than the energy needed either for liquid fuel, or for electricity to power EVs.

The value given in Table 7 for the energy to make a battery in a PHEV64 (PHEV battery with a 64 km range) is presented in misleading units, the distance traveled per year even though some of that travel is powered by the generator. The footnote for Table 7 states:

We divide by the annual kilometers of use of the vehicle. It may be more reasonable to divide by the estimated kilometers of CD mode operation.

"CD mode" means "Charge Depletion mode," that is, traveling while the battery in the PHEV is discharging.

The annual distance driven appears to be derived from the following statement on page 19:

The average daily per vehicle driving distance in the U.S. is approximately 60 km [25]....

Thus the annual distance driven appears to be:

60 km * 365.24 days/year = 21,900 km / year

And the energy used to manufacture a 17.0 kW·hr Li-ion PHEV battery (i.e. for a Chevy Volt) is:

109.7 kJ/km/yr * 21,900 km/yr = 2.40 GJ = 667 kW·hr = 2.28 million BTU

This is 3.5 times less energy than used to make a comparable lead-acid battery. Since the battery in the Chevy Volt is cycled between 30% and 80% charge or about 8.5 kW·hr, the energy to manufacture the battery is equivalent to 79 discharges of the battery.

I think they're using lifetime miles:

"For those interested in doing some sensitivity analysis computations concerning our current estimates of the energy and emissions impacts of the batteries, we provide this separate table (Table 7) of the energy use and emissions due to the battery packs alone, for one battery serving the entire vehicle life."

From section 5.2, page 16.

I agree, it's contradictory, but annual miles doesn't make sense to me.

I would use 150,000 miles, as that's the Volt battery warranty.

If the footnote of Table 7 is a misprint and the lifetime distance the vehicle travels is 150,000 mi (241,000 km), then the energy used to manufacture a 17.0 kW·hr Li-ion PHEV battery is:

26.7 GJ = 7,340 kW·hr = 25.1 million BTU

This is 3.2 times more energy than used to make a comparable new lead-acid battery, or 864 discharges of the battery as used in the Chevy Volt, a bit more significant. If the vehicle is driven 40 miles / day for 10 years and 3 months, the energy used to manufacture the battery is 23% of the energy used to power the vehicle. Assuming the battery is 70% efficient in storing energy over its lifetime, the energy used to manufacture the battery is 16% of the energy used to charge the battery. These values would be doubled if the battery is replaced once during is expected lifetime.

Li-ion should be 90+ efficient, but there are other losses. Overall, the Volt is expected to use .25KWH/mile.

These values would be doubled if the battery is replaced once during is expected lifetime.

Well, probably we shouldn't, given that we're just calculating backward from Gaines' numbers - if she assumed 2 batteries, then I presume she'd have amortized the energy per mile over half as many miles.

I'd like to know the composition of the input BTUs: process heat from natural gas or LPG would count roughly 1/3 as much as electricity BTUs (given that it takes 3x as many heat btus to generate electricity BTUs, and electricity BTUs can be converted to 3x as many heat btus with a heat pump).

Americans use twise as much electricity as Europeans

And I know that in the netherlands we are living well and we could reduce demand for electricity by 30-40 % without loosing any comfort.

Think about all the money wasted on new power plants which could have been used different...

Half your consumption and solar is getting more and more attractive

In teh netheralnds the average houe hold uses 3500 kWh per year, easily reduced to 2000 kWh per year. to cover this for 30 years with solar (950 W/kWp/year) you need to install approximately 2000 WP on your roof. Cost for thsi Appr. EUR 8000 installed and for the next 30 years you should have to replace the inverter once.

Although not cheap it's definately not out of reach for most people in the Netherlands and it is getting cheaper every year.

Cost for electricity in the netherland includeing tax transport etc. EUR 0.23 kWh

Molten salt? "Sustainable nuclear?" Holy cow guys, have you ever heard of this thing called "toxic waste?"

Here's another Pro Tip, from someone who actually works in Solid Waste: it exists.

Solar thermal power plants that use molten salt for thermal storage typically use a mixture of Sodium Nitrate and Potasium Nitrate. It is not toxic and will not burn.

It doesn't burn but is a strong oxidizer - and can make things burn/explode. Just a thought.

It is a strong oxidizer when mixed with sulfer and carbon in gun powder. But in most situations it is simply a corrosive material. Most metals will not burn or explode when they come in contact with molten salt. Therefore a spill at a power plant will not cause a fire or explosion.

Actually, despite the fact that nuclear as opposed to renewables has received far more subsidies for decades, nuclear is still producing less energy than renewable options do.

Nuclear power has dominated government spending on energy research and development, accounting for over US$159 billion between 1974 and 1998. Although its share has fallen, it still accounts for 51% of the OECD energy R&D budget:

Austria has 995 MW of free fuel wind power but no kWh producing nuclear power plant and yet its taxpayers pay 40 Million Euros every year on Euratom while only paying 24 Million Euros on its kWh producing free fuel wind farms:

The Energy Department recently concluded that waste storage needs for existing nuclear power generation will cost $96.2 billion more than anticipated, in part because of the inability to advance the Yucca Mountain (Nev.) disposal site in a timely manner. A waste solution won't come cheaply.

The cost of cleaning up existing waste is higher than previously thought. The UK's nuclear waste clean-up programme could cost more than £70bn, according to the Nuclear Decommissioning Authority (NDA).

$24 billion for 2 new nuclear reactors and consumers have to foot the bill in advance:

Progress Energy spokesman Buddy Eller says that because of those high costs, if it weren't for the Florida law, passed in 2006, his firm wouldn't have considered the project.

President Barack Obama, acting on a pledge to support nuclear power, will propose tripling U.S. loan guarantees for new reactors to more than $54 billion, an administration official said.

And as opposed to wind, nuclear power requires expensive taxpayer dependent organizations such as EURATOM and IAEA to promote nuclear power.

And yet despite all this tax-payer support nuclear power keeps on losing market share, while wind has added 37.5 GW of new capacity last year.

You don't need water to clean mirrors or PV. A good sized puff of air can do the trick as demonstrated by the Mars rovers. They could use a large vacuum cleaner to suck the dust off the mirrors using a small fraction of the plants electrical output.

You cite the moon? No moisture, no wind, no pollution, no acid rain, no dew and the only dust raised is by a passing moon buggy.
You need to get out more, the TV is not the world.

when did they move the Mars rovers to the moon ?- )

oops sorry Mars................but similar.
Still, I have solar panels and I need water to clean them.
Dust blows and rain does the rest. I clean them fairly regularly.
Dew and rain makes dust stick.

They talk of magic materials, or coatings or ionization or some combination of some such that will make that less of a problem, but...I'll go with the Missourans on that one, 'show me.'

My neighborhood isn't much for solar in winter-mid Nov to late January a low ridge about a half mile south hides the sun completely at my house-summer we have long, long hours of sun and some sticky dust (super fine loess) intermixed, especially of late, with some world class forest fire smoke. Blow a little ash and tree sap around with that and I'm betting water rinse will be required. But lately it has just about stopped raining here :-( and dew is rare...I'll have to drop by the Cold Climate Housing Researh Center and see what they have found in this last year. Their arrays are vertical and some track the sun, which might be the only way to go in these low angle parts.

Still, I have solar panels and I need water to clean them.

So what?

The US has no problems washing 250 Million cars regularly.

Why would it be a problem to wash 100 Million PV-roof-systems, which NEVER drive on dirty, salty roads at high speeds?

Besides, how many windows are never washed and yet the sun still shines through?
Even a PV-system with dust on it will produce power.

Roof mounted photovoltaic panels do not require much water for washing. Dirt buildup on the glass does not reduce the efficiency much. Rain usually is enough to wash them off. Because their efficiency is much higher, solar thermal systems are much more sensitive to dirt accumulating on the glass or mirror. I use vinegar and a paper towel to wash off my solar hot water panel every one to two weeks. Water use with solar thermal systems is a larger factor.

PLUS, if you're in a really water-constrained environment, you can gutter the water running off your panels and reuse a great deal of it.

It's a tiny issue, compared to the alternate road we're currently driving down..


Only real issue with storage now is that installing it makes NO SENSE as long as the utility is still running any Nat. Gas peakers

That isn't necessarily the case. Think of a solar thermal plant with three compnents with significant capital expenses.
(1) The mirrors, and collecting component.
(2) The generator, which turns collected heat into electricty.
(3) If present thermal storage.
If you build (1) and (2) to the same capacity, there is no point in (3), as any heat generated can be converted into product real time.
But try reducing the size of component (2). The excess can then be stored and use later on. This implies that for an undersized generator, that storage increases its usage. Undersizing the generaator, and adding sufficient thermal storage means you still get as many KWhr per day, but have spent less on the generating plant. Of course the savings on (2) have to be greater than the cost of (3) for this strategy to pay.

You are correct but the problem is that the generator (plus auxiliary equipment) only accounts for about 15% of the cost of the plant. So the saving you get for utilising this component for a few more hours a day is minimal. In most cases it won't offset the additional cost of storage.

The big benefit of storage is that you can shift electricity generation from the midday period of peak sun to the late-afternoon and evening period of peak demand — when the power is worth considerably more.

Wouldn't shifting the demand earlier with time-of-day pricing be cheaper?

They complement fossil fuels. Fossil fuels will continue to be around . . . the point is to reduce dependency on them. Sure, the ultimate goal is to eliminate dependence on them but that is 100 years away. Start small.

And solar PV's schedule matches perfectly with peak demand.


If we reduce utilization of coal plants by 90%, that's good enough. Keep the plants around for backup, for the rare times that wind and solar output are low for an extended period.

12.5 cents per KWH? Please, do your homework:

And what do you suppose solar thermal panels are made from? Just sand? By the way, these things don't save as much water as you think once you account for manufacturing!

p.s. read the actual article! It's not promoting "biofuels," it's promoting "biomass!" Might want to brush up on your thermodynamics ;)

I believe you're confusing photovoltaic solar with thermal solar. PV solar is still expensive (although costs are dropping), requires exoticish materials and has a pretty difficult manufacturing process. Solar thermal is something else. If you're building a solar thermal plant, then the materials aren't exotic - all you need is a bunch of mirrors (think polished metal)and a dark colored collector to heat up and a method to use that heat to run a heat engine (be it a steam turbine, or a sterling engine).

As for costs, $0.12/kwh is about what California utilities are willing to pay for solar power and it is on that basis that the solar energy companies are building their plants here. Whether they can actually achieve this is another question, but the people who are building them seem to think that they can.

And what do you suppose solar thermal panels are made from? Just sand?

Yes, actually. The primary high-tech item is glass mirror (sand).

The following astatements are taken directly from Executive Summary: Assessment of Parabolic Trough and Power Tower Solar Technology Cost and Performance Forecasts - Sargent & Lundy LLC Consulting Group Chicago, Illinois . These are independent power engineering experts using their own VERY CONSERVATIVE assumptions, and historical costs of eg. turbines, generators, etc. etc.

• Assuming the technology improvements are limited to current demonstrated or tested
improvements and a deployment of 2.6 GWe of installed capacity by the year 2020, tower costs
should be able to drop to approximately 5.5¢/kWh
• Assuming the projected technical improvements are achieved by an active R&D program
combined with incentives and deployment of 8.7 GWe, the tower costs projected by Sunlab of
about 3.5¢/kWh could be achieved.

And I'm sure the desert plants won't miss having all that land...p.s. how you gonna transmit all them holes?

that's right with COPPER YOU DON'T HAVE

Aluminum is the metal of choice for utility power lines because it is corrosion resistant and a good electrical conductor. It is the most abondant matalic element on earth (8.3% by weight). Who needs copper?

Its not like copper is rare either.

And one point made in the post is that you don't *have* to put plants out in the distance and build new transmission capacity - put them on brownfield sites near cities and you save time and money and transmission losses...

So that's it? 3 completely off-topic comments on an engineering study whose topic is directly on the issue of the article.

1) I'll bet not one of you posters read even the executive summary.

2) It looks to me like this site si simply being used by people to endlessly re-iterate preconcieved positions.

I may not be back.

Errr - I'm not sure why the 2 replies to WE's useless comment count as 3 off-topic replies.

I thought your link was very useful and appropriate - if you go you'll be missed...

I also just was replying to WE useless comment. I have no problems with the link you posted. However it is my personal belief that Solar Therema power will grow at a much faster rate than indicated in many reports.

Until 3-4 years ago PV panels were made with silicon chip reject material. Chip level silicon is expensive, therefore so is the reject material. Silicon substrates used purposely for PV can be a much lower quality and therefore cheaper. This has been the biggest change in PV silicon price reductions. There is also thin-film to consider, but it is still magnitudes less efficient.

I understand thermodynamics very well, I recommend one takes 5 minutes to read up on solar energy systems. Until such time, you may be Wasted Breath ;-)

The common crystalline solar PV doesn't require exotic materials. The most common element in the earths crust (after Oxygen) is silicon. Fancy super efficient multijunction cells, and moerate efficiency -but cheap thin film use exotic materials that may present scaling problems.
BTW, the thin film stuff has efficiencies of around 10%, versus 14-18% for the more expensive silicon only varieties, I wouldn't describe them as much lower quality. And new tricks are being invented all the time that need less and less silicon.

Until a bit more than a year ago, solar silicon was in short supply, which meant it was expensive. Since then the Chinese have opened up lots of new solargrade silicon manufacturing, and the price has dropped severalfold. I think some Chinese plants can manufacture PV panels for under a dollar a peak watt, but damand is great enough that they can sell them for multiples of that price.

There is pretty much an endless stream of news about optimisations for both PV and thin film solar production - it will be interesting to see what happens to prices over the next decade...

The usual problem with comparing energy rates with newer [sic] solar technologies against existing FF generation is understanding marginal rate of new generation. An existing NG CC plant may be producing at ~4.5 cents per kWh, but that plant was constructed with a) cheap money, aka Greenspan low interest rate years, and b) with NG contracts at $1.50 per MBTU (or 1,000 cu ft.) - honestly, I forget the NG market unit most days.

Recent engineering studies have demonstrated a newly constructed NG CC plant in the 50 to 250 MW range would produce power at 12.5 cents per kWh. This price does not factor in risk to supply and/or market volatility. Nor does the price include GHG costs, should they be implemented in N. America.

The other missing link in power generation is consideration of scale and utility, (the ratio of "on time" per 24 hours, or days per year). Presently we maintain the efficiency idea that power generation plants are situated remotely from the load centre and produce one source of usable energy. Electricity is delivered from these remote locations via transmission and distribution networks. This is a dichotomic structure with the power sources centralized and the distribution decentralized.

Article A: We could dig very deep into the N. American social structure psyche to determine the underlying cause for the nature of this paradigm. Think "individualism", "rugged frontiersman", "Calvinism", etc.

So, instead we construct a 500 kW neighbourhood solar collector system in a chunk of common land. Electricity is distributed to the local customer base and interchangeably with the grid, and the heat is used in a neighbourhood energy system. [Pun warning] Nothing new under the sun here..., as my European counterparts would blandish. But why can't N. Americans get their head around this?? I return to Article A.

But in California, they insist on sticking the SCP (Solar Collection Plant) out in the desert, connect to the grid and deliver energy when the sun shines on a net 50% utility with ~30% efficiency, and BAU life goes on without any annoyances to disturb their little world. Heaven for fend! Should anyone disrupt the sacred Convenience.

("Yes, yes, you are right, I do need a Soma - my apologies...")

The rant is not even very valid about photovoltaic. It says many panels are made from gallium and arsenic.
Gallium arsenide cells are used on space vehicles, They are almost unknown for terrestrial applications.
Something like 95% of terrestrial cells are made from silicon in one form or another

Indeed, I've installed a few hundred PV modules on rooftops and have never seen a Gallium arsenide cell in my life.

I dunno, stick around for another 100 years or so and I think you'll find that solar (wind, hydro, wave, biomass/biofuels) energy is all we've got ;-)

Alan from the islands

Not true - there's geothermal and tidal power as well :-)

Amazingly, tidal power is sourced from the rotational energy of the Earth. Earth's rate of rotation slows down slightly as a result, and the Moon is actually being accelerated about 4cm farther away from the Earth every year.

How long before the moon reaches orbit escape velocity ?-)

First story in latest Drumbeat...

Solar just ain't the way to go.

There's really not much to that article. As an engineer, I yawn everytime I hear someone make claims by simply handwaving. I get my electricity for my low-energy house with photovoltaics on my roof. I laugh every time someone says it can't be done.

You could always point to the SEGS CSP plant in California which has been operational for almost 40 years now as well.

Its not like this is even particularly new technology - its just that we are now starting to pay attention to it and work towards the production volumes required to make it cheap.

Sorry Avg, but I think Greer's points are hollow. It's like the salient reminder above that Floridian offered reminding us that the Sun goes down at night. What was I thinking?!

No, Solar electric (AGAIN) is one of numerous BB's that can be very well applied when it's applicable, and we hear from several owners of PV here at this site, myself included, who use it, know it's ups and downs, and clearly see it as a valuable tool to continue to push.

Because somebody else has done a spreadsheet and the numbers didn't seem to 'pencil out' doesn't change the fact that I've now got a guaranteed source of watts from a decent range of panels, right down to my pda, which has now worked off the 'windowsill adapter' for 21months, saving Lord knows how many AA battery purchases, or countless annoying searches for the Wall-adapter to charge it up. The point in that is partly that there are a lot of advantages that will simply never show up in a typical or even a supposedly 'thorough' Cost Benefit Analysis. These work on Normal days, they work during emergencies, they can be tiny and portable, huge and stable, extremely simple to use, and highly durable.

The diffuse distribution of Sunlight is very appealing to me since it seems it would tend to preclude the kind of energy monopolization and concentration of wealth and power that has come from the traditional 'big guns' .. That '100 square miles' is probably easily found by putting a bit on our homes and businesses.. letting the existing structure save us the cost of building that 100 mile project in Nevada, and using the PV to shield and shadow the roofing as well.

If you had simply a Neighborhood grid, with a dozen houses all generating a kw or 5 apiece, then it's quite possible for members of that group to lean on this system when they have a need for an excess burst of power.. so the diffusion argument seems to me to be a plus, not a minus in this.

We still need to use far less than we do.. I don't think Solar should be assumed to bring us up to today's expected numbers of KWH/capita..

A major point of Greers article was that solar (water heating) IS the way to go! Sheesh...

...Internet-enable everything...

Sounds great. Bad idea. These plants will take on more and more of the production of electricity. And now they want to open them up to hackers? Security had better be a much bigger piece of the up-front costs. There is a reason the financial system has its own network.

My thought also.

Talk about Peak Complexity..."monitoring into everything. So we have a microprocessor in every mirror and we have statistics second-by-second on the status, position, reliability, pointing accuracy — everything — of every single mirror."

What proportion of todays financial transactions happen on IP networks (Internet)? If IP networks like todays had existed in the 1980's, would the banks have used it for ALL their stuff? Certainly.

Security is a simple and well-known issue. Almost all security breaches today happen because an insider deliberately breaks the rules, which is no different than a private network would be.

Wow, Len. We've been looking for another person to teach our information security courses at the U. Sounds like you have all the knowledge needed. Interested in a job?

Nevertheless he's right - there are plenty of financial transactions being done across the internet...

In any case, "internet enable" in the article didn't mean put your CSP plant online - it meant apply the techniques for developing web sites to the development of control software for the plant - log everything, analyse everything and use the data to optimise the process.

90+% of the attempts come from outside....most fail due to existing protections. 75% of the successful intrusions come from inside, but many of those are through accidental compromising of security than intentional. Infected flash drives, mobile devices/laptops, unsanctioned wifi portals, written passwords, stolen equipment -- all can enable "inside" access without it being an "inside job". All this might fall under "deliberately breaking the rules", but that's different than "purposefully facilitating a security breach".

Many breaches are "human caused" simply because average users balk at the demands of IT security rules, and most IT security rules ignore the limitations and frailty of human brains, lack of training, other demands set by their organizations, and pragmatic cost-benefit analysis. IT security is not as much a technology issue as it is a human factors issue.

average users balk at the demands of IT security rules, and most IT security rules ignore the limitations and frailty of human brains,

To me, the classic example of this is IT security rules that require a new password monthly (or even more often). People can't remember them, so they write them on sticky notes on their monitor.

A password changed annually (or never) would be far more secure.

Allright this is long and getting off topic, but I am going to try and steer this back on topic.

First, I am an information security architect and have years of experience. That doesn't mean I'm perfect, but I have had the opportunity to learn from many mistakes.

The password problem is significant because it illustrates a cultural blindspot in thinking and how that makes change difficult.

A password changed annually (or never) would be far more secure.

This is only true if the password is reasonably secure. You are assuming that the only attack vector is someone finding the written password. There are other possible attack vectors. Depending on the authentication protocol some attacks can be done offline and significant portions can be precomputed. Since most users don't naturally pick reasonably secure passwords, security architects have to apply password change controls based on the risk of compromise for that environment.

The obvious answer here is to require stronger passwords. However the rules that are usually implemented do not necessarily increase the attack complexity enough, especially in light of Moore's law. The stronger passwords don't do enough to decrease the password crackability and thus users are left with passwords more complex than they can remember short term, but changed too often for them to get used to.

The next obvious step is to measure the strength of a proposed password at the time of change, and then adjust the duration of the passwords life in accordance with the strength of the proposed password. This rewards the users who choose strong passwords. Yet with proper choices, can allow passwords that are easier to remember in addition to being stronger and thus reduce the need to write them down.

Why hasn't this obvious step been taken? Complexity, entrenched systems, resistance to change, Microsoft. Organization security policies are all designed around the old paradigm and would have to be changed. Companies that control the user interface to a large proportion of the password changes being made see no need to change. Etc. This logical next step causes many folks to recoil in fear as soon as they start thinking about what it would take to actually implement it and nothing changes.

Change is hard even when it makes perfectly logical sense. Complexity makes change harder.

All the complexity of the mirror controls is supposed to make changes easier, but that is focused on changes in regards to tracking. The additional complexity will make changes in other areas, such as security or communications a greater challenge.

I don't know about the mirror micro-controllers, but the network devices that connect them all have passwords on them. Even though such devices are usually tied back into some central Authentication Authorization Accounting (AAA) system, often they will have a backup local account configured just in case the network is down. How often is that password changed? ;)

And many such systems have engineering back-door passwords too, or at least a factory-reset mechanism. What fraction of Wifi routers have remote management enabled and the factory password remains?

Yikes! Does this apply to home wifi routers? How does one check one's own??

Yes. If you haven't changed your router admin password, get your manual out and do so...

I remember doing so on our first one, but it's been replaced twice (once due to lightning strike), and I'll have to check on the latest...

Back on topic for a second, thanks for the key post BG, as the subarctic sun arcs higher and higher in the sky I get more interested in solar power progress aroung the globe.

On the router passwords: Is there much reason to change them on a regular basis? The printed manual that came with my router was worthless and the software packed was bugged up and not Vista compatible so the first time I got it working about a half hour (and three times as much hold time)of conversation with a very helpful Spanish accented tech was required, the second time (can't remember why it was necessary) was a little quicker (as my memory did kick in a little) but the Indian accented tech wasn't near as friendly or helpful, I'm not looking forward to a third try. I did enter my own access password and other computers cannot access my router without it--is that good enough?

I don't think you need bother changing it often unless you have some data you particularly want to protect and you have a lot of people trying to access your systems - just don't leave it on the default setting.

Ahah! I called AT&T to get the IP address of my router, and checked: I did indeed change the password when I installed our latest router.



Your point is well taken, but I think he meant that in more of a marketing sense than a literal having every mirror microprocessor sitting at an Internet accessible IP address. OTOH, it would be real cool to take control of all those mirrors and fry low flying aircraft that got too close. :)

Seriously, while they could have really messed up the security architecture, there is nothing in the system that would require that it stay messed up. Given the project size and budgets, the necessary processes to put in appropriate security controls would not be cost prohibitive. That would be allowing data out of the control network, but command control of mirrors only from air-gapped internal systems. Heck, without using IPv6, there are not enough IP adresses to allow them to make these systems routable.

As already pointed out I think the complexity is much more of a problem. How are those microprocessors going to hold up in the elements? How is all that data made searchable and accessible and how much infrastructure is required for that? What level of expertise is required to troubleshoot a problem mirror?

It could be the physical tracking system, the microprocessor generating errors, the software exhibiting bugs, the software configuration containing errors, the network incorrectly transmitting data, the collection system incorrectly recording data..... So they'll need a robust trouble ticketing system and a whole set of program management processes around that...

Is the complexity cost worth the efficiency gains? I suppose time will tell. I sure hope someone is also working on some comparable dumb systems.

And if man were supposed to fly he'd have been born with wings.


I agree. I was just picking on one obvious flaw. I teach embedded systems design and programming at the U. and had designed some of the earliest microprocessor-based controllers for solar systems back in the '80s. I've been keeping up with the problems and supposed solutions, and technically all of this fancy control is feasible, but as you say, is it worth it.

Joe Tainter wrote about the marginal return on complexity in "The Collapse of Complex Societies". Very good, if somewhat subtle, point about these claims.

To clarify, there's a big difference between "internet enabled" as in connected and routing traffic to the internet, and "Internet Protocol" enabled, as in using the standard IP stack to build a communications network with. I imagine the article means the latter and not the former.

I bet they're using SCADA over TCP/IP collect the data.

Thanks for pointing out the difference wob. For Len's sake, the article also includes this:

It is good security engineering practice to avoid connecting SCADA systems to the Internet so the attack surface is reduced.

Unfortunately, vendors, technicians, and engineers all like remote access to their projects, and it is a perpetual battle to keep such systems independent.

Though it's getting better, the vast majority of SCADA systems have no modern protections -- no denial of service protections, no encryption, no robust authentication/anti-spoofing, firewalls, virus filters, or anything. They are protected by being a bit arcane and physically inaccessible.

Since these systems are new, at least some weaknesses can be rectified (most systems are hard to maintain, let alone replace, and there is typically zero budget for security enhancements).

Security guys always run into usability issues -- the goals are often diametrically opposed, and at best orthogonal. Hardly ever is a more secure system easier and cheaper to build, manage, troubleshoot, maintain, or enhance that a low-security version. Security only makes good business sense the day after the intrusion happened!

I am certainly not disagreeing with the larger security argument when talking about any type of computer network. Of course any network setup that does not follow standard Internet security practices is still vulnerable. But if done right, your attack vector is extremely limited. Just because SCADA does not have authentication/encryption/firewalling built into it, does not mean you can't apply typical IP security practices. On the flip side, just because you have a firewall in between your typical company network and your SCADA network, does not mean it's configured correctly and monitored. Human error again...

As you mentioned, the biggest security factor will always be the human one. Social engineering is way easier than actually cracking a system. All the big name hackers in the media were much better at the social engineering than the real security engineering (example, Kevin Metnick).

There was a great infosec story about a pentest that went on at a bank. A member of the pentest team hung out in the smoking area of the bank dressed in typical vendor schwag. He gave out free USB thumb drives to everyone from "XYZ vendor". Typical vendor gifts. Little did the employees know that the USB drive had some scripts on there to start logging passwords, crawling the network for information, etc as soon as the thumb drive was plugged in. Mailed all the results back to the pentest company. Simple.

Also, I completely agree with the overall theme of more complexity = more stuff to fail.

Perhaps a point I should have amplified rather than leave to imaginations is that putting all your eggs in one basket and making life easy on yourself to manage is really risky business these days. We have foreign nationals (possibly sponsored by governments) who are actively probing security weaknesses of many of our infrastructure systems. Risk is measured by the probability of loss times the $ value of the loss. For a major energy installation like these, or a nuclear plant where additional physical damage should be considered, the risks are quite high, even if the probability by itself is not seemingly that high. That is because the potential for loss is so great.

I hope they can get the large-scale solar thermal systems to be very efficient.

I like residential PV systems. Admittedly, they are expensive. However, one has to keep in mind a couple of the really big advantages of residential PV systems:
1) They generate the most power when the most power is needed: during the daytime and on hot sunny days when everyone and their brother fire up their AC systems. PV systems are automatic peak-demand systems.
2) They deliver the power right where it is needed . . . right where it is consumed. No expensive long-haul, difficult-to-permit, high-voltage power lines needed. (Coal, natural gas, and nuclear can't do that!)

So even though PV is expensive, it provides special advantages.

"So even though PV is expensive, it provides special advantages."

"Expensive" is subjective. As I often post, many people think nothing about spending $50+K on a car, $10K on an annual vacation, $?K on toys, toys, toys. They won't spend $30K on PV or even $4K on a solar water heater. It's peoples' priorities that are expensive. It's going to cost our society in ways we can barely imagine.

Right. Think what people are willing to budget for an ATV, a Motorboat, an RV, a Vacation, a 'Theater Quality Entertainment System', Kitchen Renovation, Swimming Pool ...

but while I think PV is worth it, I'd say it IS expensive, too. It's a big pill to swallow, when we've been inundated with an uninterrupted (mostly) supply of cheap watts. We won't value it properly until that regular supply is less regular, and so, more appreciated.

Yes, solar is still a trifle expensive.

That's why the sensible thing is to use affordable wind power for the bulk of our needs, and solar for peaking power.

"Yes, solar is still a trifle expensive."

$1.37/watt (plus BOS and install). How cheap does it need to get?

You could roof your whole house with these things. With incentives your investment may be minimal.

BOS and install

At $1.37, those costs are more important. If the overall cost is $3/Wp, you're still looking at $.15/KWH. That's fine for peaking, but not for the bulk of power. No, I think wind needs to be the bulk of power, at least for the moment.

To be clear, I'm allowing that it's a bit expensive, and yet is still completely sensible.

Like college, it can be a heavy investment, and in some ways the payback isn't altogether written in stone.. but with a couple well-placed choices is a pretty solid choice with a range of benefits you can barely guess at beforehand. It's worth paying when you perceive real value.

No problem with wind as another of the essential BB's as well, and agreed, it can do a lot more heavy lifting, where I see PV as the more agile little brother. The Quarterback, maybe?

While I like how we can use electricity well for a wide range of heavy physical and heat process work, I think some of it's most critical value uses draw relatively lighter levels of power, for communications, control systems, timing, sensors, micro-tools, video/graphics for which few or no other power-sources are at all practical.. in this sense, I place a high value on such dependable and portable, albeit modestly powered electrical sources.

There's lots of ways to heat water and cook dinner.. but only one thing will run our radios, phones and microcontrollers, and it usually doesn't have to take much actual power to do it.


I'm occasionally struck by the performance of my solar-powered calculator - no battery replacements, and flawless performance for 20 years...

That's one of my favorite examples. That level of calculation, which we can totally take for granted with the help of a tiny scrap of PV a half the size of a postage stamp.

My little HP 200lx is a simple Palmtop from 1995, and I glommed a flashlight PV panel onto it with just a diode for discharge protection.. and I've got all that data and those tools, spreadsheet, lotus, word processor, Numerous DOS apps, data duplicability, IR interfacing, serial interfacing .. all on a $5 piece of PV the size of a day/runner.

It's hard to remind most folks of the level of power that this very simple little rig represents, since it looks lame today next to an I-phone..

I always struck by the lack of RPN in modern engineering calculators. I should make a solar charger for my HP-41C.

I am a real fan of residential/commercial PV. It does have all those advantages you state. Also until it becomes pervasive, it reduces average and peak loads on the transmission/distribution system. But I think getting solar for widescale generation will require the development of large scale solar thermal sources. I also think we as a society need to spend whatever it takes to get those first few GW of solar thermal built. Until we get enough of the infrastructure and engineering done and paid for, the early plants will of course be uncompetitively expensive. Thats why subsidies for development make social sense. They are designed to allow the considerable learning curve for new tech to be overcome. If the first Nuclear plant had had to pay the full development price of the technology, it never would have been built, woulda bankrupted the utility.

Mirrors are a very effective way to transfer heat. I place four mirrors on my deck this winter at day break. When the temperture outside was forty degrees I could maintain a temperture of 75 degrees in my den. As the day roled on I would have to open doors to keep the den at a comfortable temperture. I had to step outside several times to move the mirrors during the day but it was free heat. It seems to me, and I admit I'm just an old man, that someone could develope the use of mirrors on a small scale for homes.

Well thank Heaven for old men, then, Hotrod! Sounds great.

I've been playing with designs for 'decorative' Heliostat Mirrors that can stand on little towers in people's northside yards and toss beams of sunlight into windows on the 'cold' side of the house.

(Doesn't work in the Southern hemisphere, because all Heliostats spin backwards down there, apparently)

These could be considered Heat AND Light sources, and speaking of Internet Enabled, they could be programmed to target any old thing you liked, like your Iced-up back steps, a Glass-roofed Shed where the woodpile is drying, an insulated Compost Pile that you want to keep warm.. It could move to the window of whichever room you happen to be using then.. Just hit a preffered target button when you're leaving the house, or have it set to give a half-hour to the 'Tomato Dehydrator' box, the solar oven and the compost-bin every day.. etc.

My solution to the potential 'Neighborhood Nimby' thing is to make all my Alt-energy experiments look like really tacky, tasteless Yard Art.. like my Oversized Rooftop windmill could be a big Nylon New-Age Peace and Love Sign, with Groovy Doves, man. Those inclined to whine may hate it, but it falls neatly then into the 'Our Freedoms and Lifestyle shall be NonNegotiable!' If that doesn't work, maybe I can make 'political speech' out of it. Times have been so raw, I'm really spoiling for a good scrape anyway!

.. but I do really like the Mirror Idea.. and programming it could be fun, too!


The 1.5 MW Maricopa solar plant with 60 25 kw Suncatchers looks ready to go.

It looks like the units are being built by auto parts suppliers. Making a million of these things instead of a million or so gas guzzlers would be 25 GW.

Holy Mackerel! A whole megawatt and a half! We're all SAVED!!!

Ah, get back to your pick and coal shovel.

Thanks for pointing that one out majorian - good to see they are making progress with those things.

Hate to rain on your parade Bill, but you should data mine your tracking data. Seems that there are a progressively increasing number of brain dead mirrors in the background as you proceed through your promo presentation video!

A second question comes to mind: How do you propose to automate the necessary cleaning operations on the mirrors given the dense array and lack of access? If they are not cleaned, how much performance degradation will result? If water is used, what is the annual requirement?

At the moderate plant size chosen is thermal storage, (molten salt, saturated steam) economical or will e-solar be restricted to cyclical output?

There is a lot to admire in the e-solar design, and like most technologies it has its own particular set of problems to overcome.

From what I read it is clear to me than reprogramming their system after building them is an indication of poor optimisation in first place. Also, concentrated solar loose rapidely its performance in presence of a diffusive layer: cirus, dust and volcanic cloud. Flat panel system are much less sensitive due to their insensitivity to diffusion.

Flat panels suffer from not being able to achieve the high temperatures that concentrating systems allow. Without the high temperatures you cannot get the thermodynamic efficiencies needed to justify running a generator.

I have a question for anyone reading with knowledge of solar thermal power plants. The main objection I've heard so far, aside from their cost and their novelty, is that they consume large amounts of fresh water in operation. Is this true? If so, why, and how would it compare to the water use of a conventional coal plant or a nuclear reactor. Gallons per watt? Anybody? My two cents is that solar thermal seems like a great idea - relatively low tech, few exotic materials, and can be scaled up or down to match the market and the location. Go solar!

I think the criticism regarding water use may have some validity. The steam circuit, running at lower temperatures and efficiencies than modern coal boilers, will need probably 15% to 25% more water than coal plants in an evaporative condenser circuit to maintain vacuum behind the turbine. Trade off a bit of efficiency for less water use. Also some amount of water used to wash the reflectors on some schedule, though any of this which doesn't evaporate should be recoverable.

I'd suggest, in a ambitious plan, (which to me seems justified in SouthWest US) is to pipe seawater inland to the plant sites, using it directly for washing and to cool the condensers, then when it gets too salty, release it into the inland salt flats to replentish their water tables.

That depends on the technology. Sterling engine based solar plants use essentially no water. Other thermal solar plants work by boiling water to make steam and running it through a turbine, which is exactly what coal power plants do and their water needs are similar to a coal plant. The drawback of thermal solar where water use in concerned is that you really want to locate them in deserts (where its very sunny) and thus often have little water available. The other drawback is that in the U.S. solar thermal power plants only make sense in a fairly small area (basically the California, Arizona and Nevada desert) where there is lots of sun and little cloud cover.

It Depends on how you design the plant. Solar Thermal power plants use Steam turbins. Yes they use water, but this water is highly purified and continously recycled because of the purification costs. The same is true for Nuclear, coal, and some natural gas power plants.

The main water use is however in the system selected in the design to remove the waste heat. In most Nuclear and Coal power plants the waste heat is carried by water (a seperate water loop from the steam turbin) to an evaporitive cooling pond where it cools (the ponds are often at the base of large cooling towers). In the process of cooling some water is lost to evaporation. To make up for this water is continuously draw form a river, lake, or other water source. This replacement water accounts for most of the water demand in a power plant. Other power plants simply draw in water from a lake or river and then return all of it after one pass through the power plant back to the lake or river. Either way water is lost to evaporation. They are cheep easy ways to cool power plants.

A third way to remove the waste heat is to use a dry cooling system. In dry cooling systems hot water passes through radiators that transfer the heat to the air without evaporation. The cool water leaving the radiator is returned to the power plant to be reheated. Without any evaporation very little new water is needed. Only water lost to leak or spills has to be replaced. All cars use dry cooling systemss. Dry cooling systems generally need fans at the radiators to get the air moving and larger water pumps to overcome friction losses in the longer pipes. So dry cooling system generally cost more to operate and use some of the power generated by the power plant.

Water use for cleaning the mirrors has been found to be trivial at existing solar thermal plants.

What you have said is basically correct but there are a few refinements that people need to be aware of.

There are three types of solar thermal plants currently being built, solar trough, linear fresnel and solar tower.

The solar trough plants have been in service for more than 20 years. They are still undergoing improvements to the design to decrease collector manufacturing costs. They have the advantage that the deployment of solar collecting surface area is relatively cheap. The drawback with their basic design is that the level of concentration is limited and thus they only achieve steam temperatures of around 300 degC.

The linear fresnel collectors are similar to the troughs in that they also have limits to their solar concentration levels although it is marginally better and can achieve steam temperatures of around 380 deg C. These devices have the cost advantage in that they utilise flat mirrors reather than the very expensive preformed curved mirrors used in the solar troughs.

Solar tower plants use an array of heliostats concentrating on a single point collector. Theoretically they can achieve solar concentration factors that provide for supercritical steam temperatures of 580 deg C but have only been used up to about 540 degC to date. The disadvantage of this type of plant is that the mirror surface area is quite a bit more expensive because it has the be controlled and directed in two planes.

The above operating temperatures are critical when it comes to the plant water usage. The overall thermodynamic efficiency is governed by the differential temperature between the collector and the condenser temperature. The condenser being used to condense the steam after it passes through the steam turbine. Wet cooled condensers can achieve temperatures around 40 deg C whereas dry cooled condensers operate at a much higher 60 - 80 deg C. The higher temperature of the dry cooled condensers make them unsuitable for use with either the trough or linear fresnel solar collectors. The reduced temperature differential makes this combination unacceptably inefficient. Although having said that there are some operational plants configured in this way. Solar towers on the otherhand can be fitted with dry condensers without too much of an impact on their performance.

As a rough guide (a lot of factors such as ambient conditions etc. come in to play) a wet cooled plant will utilise around 5000L of water per MWhr generated. A dry cooled plant will use about 50L per MWhr. Not including mirror washing.

Thanks for providing some facts phoenix - a bit of a rare commodity around here when people start worrying about water consumption.

Its not like these things are a novelty - you (those spreading FUD about water) could just go and get the data for the long-running SEGS plant - which is presumably an upper bound for water consumption given it was the first generation plant using this technique...

Hi Gav,

I'm disappointed that so many people are looking for reasons for csp to fail rather than for it to succeed.

Most of the arguments Against aren't really applicable if one stops to consider the day to day ereality of our energy situation and the time frames involved in the real world of construction, depletion, and finance.

It seems to me that it is perfectly obvious that all the power that can be generated with csp plants that can realistically be expected to be built over the next decade or so can be used in real time.This is likely to hold true as far into the future as the plants will last before they are due for replacemebt with new mirrors, generators, etc.Therefore storage is a non issue for at least a decade.

It also seems to be a sure bet that as electricity inevitably becomes more expensive, and smart appliances more common, that it will be possible to easily shift a good bit of demand to times when csp is cranking-there is no reason a refrigerator should not have a water ice reservoir built in that would enable it to function as an old time ice box for a day or so, excepting a tiny bit of power used for an air circulation fan.

If things fall part and society goes mad max in a short while,all these discussions are academic anyway. But if as seems more likely to me at least , we stagger along in some semblence of bau, all crippled up but still on our feet,we can make good use of csp without any worries at all about storage or convenience-people will be very glad to be able to run thier washing machine any time at all , ditto recharging thier electric golf cart cum commuter car etc.We have decades, technically, to transition to renewables and reduce our lifestyles-this is not something that has to happen overnight.

What may happen in respect to the economy and energy couild of course be a real show stopper of course-but that just gets us back to the academic, rather than the realistic consideration , of the issues.

A house with ac could be slightly overcooled in the afternoon to partly shift the ac load to an earlier hour,etc, or a water reservoir used to store site collected solar heat in the cold season could be chilled by the ac system during the summer during peak csp production and used for cooling at night.

A great many jobs could simply be done at different times of the day too even without smart appliances-a retired person could verily easily do her laundry at 2 pm to benefit from a lower peak rate, and time based rate structures seem to be a coming thing.

The readers as a whole seem to be missing the fact that csp is really on a cost reduction roll.Maybe the engineering types are just taking this for granted and not saying much in this respect.

The people who are whining the loudest about a few relatively minor changes in life styles aere more than likeli the ones imo who contribute the least to our economy in real terms while extracting a better than average living from it.My guess is that they are in for a few lessons in the school of hard knocks before too long.

But maybe the biggest thing of all that is being overlooked is the fact that as renewables come on line , they not only extend the supply of ng that can be used for load balancing at night and on bad days; renewables can and do help hold down the prices of ff energy.I strongly suspect tht every dollar spent on renewable subsidies will be repaid to our society several times over as a result , over a period of a decade or two.

This does not mean of course that we should not be directing more money into conservation and efficiency and less is to renewables for the moment.An d we certainly need to to be supporting the renewables that hold the most promise for large scale scalability at the earliest date rather than the ones that don't seem to be as suitable for large scale ff savings.

To me this seems to indicate that wind and csp are most deserving of subsidies for actual production capacity at the moment.Pv should be generously supported with research money. if there is then a pv cost breakthru it should get more installation subsidy money.

Here's my lead-in, so here's my lead.

I work on improving csp using stirling engines. Blll Gross first looked for stirlings for his system, didn't find any and went to nice conventional steam. I like his system concept so spent some more time on dedicated solar stirlings. What I came up with was a stirling that did nothing but pump water, making it much cheaper than other stirlings. The water from a field of stirlings goes to a big water turbine, which is totally known tech, and highly reliable and efficient.

Of course pumped water can store energy, another totally known tech, and widely used. This water is used only as an energy transfer/storage, and is not blown out to atmosphere.

The stirling/pump costs about $150/kW to make. It is a very simple machine that uses nothing but steel and aluminum, and nitrogen working fluid. It has about 15 years of life and almost no maintenance ( see NASA space stirlings for confirmation)

At this point the usual suspects will dollop out the usual expletives. I am not gonna answer. Let the market decide.

PS- So why not just open the fridge to the fridged air when it is frigid, and use a little fan to blow coolth into the fridge instead of a lot more juice to run the compressor to pump heat to a heated room??

And, use a coldstore hole and a hotstore hole to cool and heat the house (old, old idea).

And-- solution to all energy problems- make the price equal the cost--all of the cost.

I like solar thermal energy and wind energy, but I don't expect miracles.

I'm with a lot of other posters here in doubting solar energy is going to save us from PO .. but I do think longer term it may become a more relevant part of our energy mix.

The problem in Australia is that our government seems completely oblivious to PO and the planning we to do to mitigate its effects, instead wasting our tax dollars on misguided 'green schemes'. One of the worst examples being the silly subsidies being paid for residential solar hot water systems - draining money away from wind and solar plant research.

And while I'm on the subject of hot water and dumb government grants, here's another classic: subsidies given to sports clubs to install (conventional) hot water systems for virtually nothing. Koondrook Barham Footy club installed 17. As an Aussie Rules side has 18 players on the field that's nearly one hot water system per player !!!

Luckily most clubs were not this stupid, looks like they realised how expensive they would be to run (and completely waste energy).

Metal, I agree with your POV entirely. PV is actually quite useful for disparate locations, such as if you need a radio transmitting station in the desert or something. In that case, you'd actually save net energy building PV rather than connecting to the grid.

But it DEFINITELY is not as useful as many people seem to think, and will always be a less important part of the "grid mix" of fuels than wind, biomass, smart hydro, and of course, good ol' trash! Or at least it would be, if people would just open their eyes and see what their minds already know, were they not too closed-off to realize it. You would think people familiar with peak oil would be more willing to consider the consequences of "peak solar!"

By the way, there was a great repost here on this same topic on TOD today from Energy Bulletin. Everyone here should read it!

"Peak solar" ?

Fossil fuels deplete - solar energy doesn't (not in any timeframe meaningful to humans anyway).

So I wouldn't worry about it too much if I were you...

I wonder if the loan guarantee to Brightsource will soften objections to nuclear loan guarantees though I doubt it. A general vibe I get about the likely approach to CSP in different countries is
US - production tax credits, green energy quotas
Europe - feed-in tariffs and sale of carbon credits
Australia - gas backup will be deemed honorary renewable.

It would be good if former junkyards or extensions to industrial estates could economically produce a few MW. I think the main help will have to come from high carbon taxes.

It would be nice to see a carbon tax but it doesn't look like happening any time soon.

In the meantime the RET is the best we can hope for...

At the moment the RET (Renewable Energy Target) is so corrupt, that in its current form it's a negative factor.

Many things like Coal seam methane contribute to RET now. Also REC (Renewable Energy Certificates) where given away with programs like the residential solar hot water systems subsidy. Way too many for the contribution the systems actually make.

So there is a glut of RECs, meaning their value has collapsed. This has put real investments into limbo causing real economic damage. One example is sugar mills. Some in northern NSW have been investing in burning mill by-produces to generate electricity. This requires the associated RECs to be priced at a particular level. Government mismanagement has caused several 10s of million of investment to be put on hold and left existing investments as lose producers for the grower owned cooperatives that made them.

This is an inherent risk involved with making investment decisions based on government programs and subsidies. Use government programs, but get the money up front.

OK - the RET is a mess but it will get sorted out and as long as the target is significantly greater than current capacity we'll be building new renewables plants.

Yer, hope it gets sorted out. But will require both increasing the target over time and removing things like coal seam gas from qualification.

Don't see it happening, governments, particularly the states are addicted to coal & gas royalties. No royalties, no money to pork barrel city seats. All the states, even more decentralised Queensland, are now so urbanised that government is won and lost is the state capitals alone.

Update: As of just over a fortnight ago (26/02/10), the federal government addressed the residential solar hot water systems RECs issue. The market has rebounded from under $30 to $43.

I do say, some of the comments posted here today make me wonder if people have ever heard of this little thing called a "direct fired biomass power plant." Solar thermal energy at its finest!

And best of all, it's cheap!

And it scales !

Oops - oh well...

I do say, some of the comments posted here today make me wonder if people have ever heard of this little thing called a "direct fired biomass power plant."

Yes I rather think we have - ever run the numbers on efficiency?

Biomass is only about 2% efficient at catching the solar energy at best and that allows nothing for the energy required to plant or harvest it.

You need to compare electricity with electricity to get a fair comparison so you need to burn the biomass to make the electricity. This could be maybe 40% efficient if just burnt or ~85% if a CHP system is used - provided the energy to transport the biomass to somewhere where the heat could be used is small.

Thus the biomass sunlight conversion efficiency is unlikely to exceed 1.5% at best and could be much lower.

Compare that with PV or solar thermal @ say 10%, even if you stored the electricity by conversion to synthetic gas or oil at about 50% efficiency, then burned that in a power station @40% to allow energy storage you would still get ~2% assuming none of the waste heat were captured and ignoring that this is a worst case storage method you would only use once immediate demand was saturated and if everything else was fully charged.

Even that neglects that solar thermal works best on desert land where biomass won't grow anyway (and think of the water needed for biomass vs solar).

Actually with 1 ha of Miscanthus (one of the most productive biomass option currently available) you get 300,000 MJ/ha.

With an efficiency of 40%, that's 23,150 kWh per ha.

With a PV system at 15% efficiency and 1500 sunhours per year you get 2,250,000 kWh per ha.

For a given area you get almost a 100 times more electricity than with biomass!

For a given area you get almost a 100 times more electricity than with biomass!

Yes indeed - I was quite deliberately comparing the worst solar electricity system I could think of to the best biomass. The only advantage biomass has is that it is storable as harvested, assuming electricity to storable synfuel is 50% efficient (I cannot remember where that number came from) and 40% when you turn it back to electricity then you have a 20% efficient storage system so your 100x would still be 20x even if you wanted to store the energy for months.

Also the usual comments on CHP and heat pumps apply - if you use your stored synfuel via electricity for winter space heating you get something like 20% x3 (for the COP) + 30% heat = 90% of the solar system's original output back as on demand heat (i.e. about 13% overall solar conversion and storage efficiency for a 15% panel). No way biomass can match that however you try to spin it although the difference won't be 100x.


So, kids, what did we learn today?

PV is great, as long as you don't try to make it too much more than zero percent! And of course, the best forms of Concentrating Solar Power are, in descending order, trash, biomass, water, and wind!

'PV is great, as long as you don't try to make it too much more than zero percent!"

It's about 80% for me. Definitly not WastedEnergy. Good luck when your lights go out.

Thanks for snagging my tax dollars. Oh well, at least it was a better waste of energy putting solar panels on your house than digging for oil in Iraq. Your panels probably didn't get anyone killed...unless we're talking about your Flat Panel once you "recycle" it!

p.s. I bet I save a lot more energy just by turning off my "TV" than you ever will with your "PeeVee Herman"

Learn to conserve resources the right way...and OPEN YOUR EYES!!!

Waste and biomass are fine as far as they scale -probably a few percent of total consumption. It represents just another greenish BB, not a solution to the whole problem of powering an advanced society. The reality is that wind, solar PV, solar thermal, nuclear, biomass, are all complementary sources. We need not think of as competing with each other (though they do compete for research resources).

The other pathway to getting to solar thermal is hybrid plants. Already several are in the planning stage. A NG fired powerplant, that substitutes solar heat when available for some of the fuel. Then the next step would be to bump up the solar contribution so you don't need NG during the sunniest times. Then bump it up still more, and add thermal storage. This way a plant can transition from getting minor fuel savings via solar thermal, to getting most of its energy from solar thermal. As the price of NG grows over time such a "hybrid" plant can evolve to needing less and less NG.

Don't worry, WastedAssumptions. I didn't spend one cent of your precious tax money. I figured this stuff out long before your govt did. It seems some folks never will, though.

Here's to highly efficient, low power homes with un-interuptible power supplies..

"Learn to conserve resources the right way...and OPEN YOUR EYES!!!"

ps: WastedWords, I'd be glad to compare my resource conservation strategy to yours anytime. Prepare to get your conservation but kicked. (Hint: Our PV, solar thermal and passive solar systems paid their energy debt off years ago.)

I could go on, but the sun is up and the PV panels are already producing 3.6KW and the solar heated water is hot, so I'm going to run the dishwasher and the Maytag washing machine and start the bread machine while I watch a lecture on the big screen TV. I better warm my coffee up in the microwave first.

How do you think that this was the message today?

You're pushing Biomass awfully hard, and pronouncing conclusions that I didn't hear except from you.

The Biomass waste stream does make sense to use well, but like with the Waste Vegetable Oil that quickly has become constrained as so many companies formed to make Biodiesel, a 'raw material' subject to the vagaries of the restaurant industry, consumer demand and preferences and other things, it seems clear that we'll be vulnerable to 'Peak Waste' long before we'd have a likelihood of seeing 'Peak Solar' ..

I'm curious how you arrived at these responses.

"We are like tenant farmers chopping down the fence around our house for fuel when we should be using Natures inexhaustible sources of energy — sun, wind and tide. ... I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that."- Thomas Edison, 1931

Shortened version of above is recycled on TOD every now and then.

Old Tom was right. And, sorry, we're too late. And we allowed our population to explode to 7 billion in the meantime. Stupid humans!

John Michael Greer had a few things to say about solar energy. Here's a sample:

Still, the problems with net energy and economic triage both ultimately rest on thermodynamic issues, because the exergy available from solar energy simply isn’t that high. It takes a lot of hardware to concentrate the relatively mild heat the Earth gets from the Sun to the point that you can do more than a few things with it, and that hardware entails costs in terms of net energy as well as economics. It’s not often remembered that big solar power schemes, of the sort now being proposed, were repeatedly tried from the late 19th century on, and just as repeatedly turned out to be economic duds.

With all due respect to this guy, he is not a scientist or engineer, and does not have any training or expertise in these areas. His wikipedia page states he is an "author, independent scholar, historian of ideas, cultural critic, Neo-druid leader, Hermeticist, environmentalist/conservationist, blogger, novelist, and occultist/esotericist".

In other words, a kook.

I quite like JMG but it would be handy if he quantified what he thinks the net energy for solar thermal (or PV) is.

Most accounts show it to be substantially positive, and the numbers get better every year....

JMG goes on to say this:

it makes more sense in an energy-poor society for people to gather relatively diffuse energy right where they are, and put that to work instead.

I agree. Solar thermal (water heaters) and PV can be installed at/near the points-of-use, requiring no investment in additional infrastucture. This idea of distributed deployment is an old one.

crobar, even though a person's background may influence your emotional response to what they say, you should really address what they say, rather than who they are. JMG seems to be well respected, is very well read and has a knack of explaining what he writes well. He usually makes many good points.

I would really like renewable energy to succeed but I'm sceptical that solar thermal will ever come near wind power in terms of cost and total delivered power.

Why? Look at the feed in tariff required to make a profitable large scale investment in solar. In Europe it is around 0.30 Eur/KWHr.

That is over 5 times what Wind Power operators get in Australia (around 0.08AUD$/KWHr) and ten times what a coal-fired generators gets (0.04 AUD$/KWHr).

Then you look at the technology. Somehow there has be a factor 5 improvement in cost to be comparable with wind, and 10 times to be comparable with coal. Basically there is not much room to make that much improvement. The limit is the cost of the mirrors and the mechanical tracking systems.

I think there is more hope in PV where one can keep searching for new improvements in the Quantum Mechanics of direct conversion of photons to electricity.

The basic problem with solar is that it has to make a device that is at least 15% efficient, costs the same as concrete ($80/ square meter) and is about at durable (30 year lifetime).

You can't really look at the subsidies - you have to look at the costs.

Wind is about 50% of the cost of the best PV installations ($2/Wp and 30% capacity factor, vs $3/Wp and 20% CF). That's a big advantage, but it's not 5x.

Does a .2 millimeter layer of concrete really cost $80/sq M? :~}

And, of course, CSP should be cheaper - do we have current costs in any of these articles?

Wind is about 50% of the cost of the best PV installations ($2/Wp and 30% capacity factor, vs $3/Wp and 20% CF). That's a big advantage, but it's not 5x.

Hi Nick, those feed-in tariffs are real numbers but taken from two different locations. Maybe it is not fair to compare them. Australian wind operators definitely get around $AUD 80 per MWhr. We have a bipartisan mandate in Australia to increase renewable energy generation to 20% of capacity. This will be achieved via tradable Mandatory Renewable Energy Certificates. There was a controversy after about 2-3 GW (Peak) of wind installations was put on hold because these certificate decreased in price to around $AUD 36 per MWHr because solar hot water heaters could compete for same certificates. Once this was fixed, the certificates increased to $41 and the projects are going ahead. The average wholesale feed in price is around $40 per MWHr in Australia so that makes the effective feed in tariff around $80 per MWHr.

According to google 1 AUD = 0.66 Eur so that $AUD 80/MWhr becomes 52 Eur/MWHr, which is more than 5 times smaller than the 300 Eur/MWHr for CSP quoted in the linked article.

The link I quoted looks believable and matches numbers I've heard from presentations I've seen on European CSP projects. I don't know if PV gets the same feed in prices but if they did one could expect Europe to be flooded with PV installations.

Does a .2 millimeter layer of concrete really cost $80/sq M? :~}

Almost certainly not but it wouldn't last 30 years of people walking on it either :-)

Again, you can't compare subsidies - you have to compare costs.

Let's give an arbitrary example. Let's say coal costs $.05/KWH, wind costs $.06, and solar costs $.10. In order to equalize their costs wind would need a subsidy of $.01 and solar would need $.05. The solar subsidy would be 5x as large as the wind subsidy, even though solar cost only 1.7x more.

Furthermore, subsidies don't even give us the kind of information about underlying costs that the above example suggests: if developers know that a subsidy is coming, they will wait for it even if they don't need it - why build without it, if you know it's coming?

The numbers 56 Eur/MWHr and 300 Eur/MWHr aren't subsidies on top of whatever extra price developers can get for their electricity. They're the amount developers get paid to produce electricity. Presumably those numbers are close but above the actual cost of production. If the numbers were substantially above production costs (say a factor of two) the technology would expand too fast to be sustainable.

This has actually happened with PV subsidies in Australia for example. I believe something like this happened with PV subsidies in Spain too.

So I think the profitable feed in tariff (but not too profitable!) is a good way to estimate total levelized costs. In the case of CSP vs Wind it is 300 Eur vs 56 Eur which this factor of 5 difference. That is a lot for a rather mature technology to bridge.

You raise a really good point with this.

if developers know that a subsidy is coming, they will wait for it even if they don't need it - why build without it, if you know it's coming?

I do wonder how governments will handle this. What incentives exist for developers to actually pass on potential lower costs to rate payers if they can get governments to set a guaranteed high price for their goods? (Electricity)

Some thoughts:

I think European feed-in tariffs you're looking at are for PV, not CSP.

I don't think you can compare costs in Germany or Italy to Australia or SW US, given the difference in insolation.

The 300 Eur/MWHr figure is an initial/current amount, which declines with time.

What incentives exist for developers to actually pass on potential lower costs to rate payers if they can get governments to set a guaranteed high price for their goods?

Not much. Governments have to figure out the real costs. I suppose they can use trial-and-error, but as we've seen, that's painful.

costs the same as concrete ($80/ square meter)

Actually First Solar has reached around $80/m2 production costs with its PV modules.