Got Storage? How Hard Can It Be?

This is a guest post by Tom Murphy. Tom is an associate professor of physics at the University of California, San Diego. This post previously appeared in Tom's blog at Do the Math.

The recent city-wide power outage in San Diego made me appreciate my small off-grid photovoltaic system using four golf-cart batteries to store energy for use at night. Unlike most San Diegans, I did not immediately eat the ice cream in my freezer, which trucked along under stored solar energy just like it does every night. Energy storage becomes more important as we transition away from fossil fuels—already its own energy storage medium—to more intermittent sources. But besides batteries—which offer a limited number of cycles and for some types require monthly maintenance—what other non-fossil in-home energy storage alternatives might we consider, and how much energy might we expect to store in each case? We will look at gravitational storage, flywheels, compressed air, and hydrogen fuel cells as possible options. Some might even cost less than $100,000 to implement in your home.

Four golf-cart batteries used in my off-grid home PV system. Each is 12 V, 150 A-h, thus 1.8 kWh of storage apiece.

Setting the Scale

We should first establish a meaningful scale and appropriate units for energy storage. Any household will use energy at a certain average rate, or power. The average American household (of which there are about 115 million) uses 30 kWh per day of electricity—equivalent to 1.25 kW average power. Additionally, the average American household uses 35 kWh of natural gas energy per day, generally for heating applications (natural gas is usually billed per Therm, which is 29.3 kWh).

Substantial variation can exist in these numbers in any given house. For example, my wife and I use an average of 10 kWh/day in our house for electrical and natural gas energy combined, in roughly equal measure. Storage requirements will therefore vary according to usage. Conversely, the same storage will last longer in some houses compared to others. We will restrict our attention in this post to storing enough energy to cover electrical usage only.

For off-grid applications, the rule of thumb is to have enough storage for three days of zero input. Not to be taken literally, this is effectively the same as 4 consecutive days at 25% of break-even, or 6 days at 50% of break-even—in each case running a deficit of 3 days. The spirit of this post is to establish storage independence within a home, rather than rely on external infrastructure to do it for you. To the extent that you want to rely on the outside world to provide for you, the targets established here can be scaled down accordingly. The ideas explored here are plausible options that might come to mind first in a “why couldn’t we just…” sense.

Since we are trying to fit a storage solution into a home, let’s allocate a fixed volume for each of the solutions. A reasonable choice would be one bedroom-sized space. Let’s say it’s 3 m on a side, and 2.5 m tall (about 10 by 10 feet, 8 feet tall). The total volume envelope is then 22.5 m³.

Battery Reference

Since we are comparing to batteries, let’s establish a reference case. Batteries are characterized by how many amp-hours they can generate. A 100 A-h battery can put out 1 A of current for 100 hours, or 10 A for 10 hours, for instance (though the rating typically declines for high currents). The electrical power exerted by the battery is just the current times the voltage. So a 12 V battery putting out 2 A is delivering 12×2 = 24 W of power. If rated at 100 A-h, this battery would go for (100 A-h)/(2 A) = 50 hours, producing (24 W)×(50 h) = 1200 W-h, or 1.2 kWh of energy. A rechargeable AA battery holds about 2300 mA-h (2.3 A-h) of charge, which at 1.3 V turns into 3 W-h of energy.

As detailed in the Nation Sized Battery post, large lead-acid batteries occupy 13 liters (0.013 m³) of volume, and 25 kg of mass per kWh of storage.

Practically speaking, we would not fill 100% of a bedroom’s volume with batteries, because we need physical access for maintenance/replacement. If we filled 10 m³ of the available volume with actual battery, we would end up with about 750 kWh of storage, and a mass of 19 tons (better reinforce the floor!). This bank would provide about 25 days of storage for the average American electricity demand.

The lesson is that batteries are a can-do solution in terms of fitting into a house envelope. A more practical few-days of storage is that much easier. Although at approximately $150 per kWh of storage, three days of storage for the average American house will cost about $15,000 to cover electricity demand, with the cost recurring every five years or so. But let’s not worry our pretty little heads over mere economic concerns at the moment.

Since lead-acid batteries require monthly equalization and topping-off with water, have a limited number of deep cycles (500–1000 typically), and do not tolerate extended periods at low charge, it would be nice to identify better options.

Gravitational Storage

Hydroelectric dams and pumped storage solutions rely on the gravitational energy stored in an elevated mass. What could we do in a home environment? Could we get much out of our personal pumped storage tank on-site?

Let’s start small by considering the 3 W-h of energy stored in a AA battery, as computed above. One kWh of energy is 3.6×106 J of energy, so our AA battery stores 10,800 J of energy. A mass of m kilograms, hoisted h meters high against gravity at g≈10 m/s² corresponds to E = mgh Joules of energy. If we were willing to hoist a mass 3 m high, how much mass would we need to replace the AA battery? Have a guess? The answer is 360 kg, or about 800 lb. A battery the size of your pinky finger beats the proverbial 800 lb gorilla lifted onto your roof!

The lesson is that gravitational storage is incredibly weak. A volume of water the size of our bedroom raised even 10 m above our home in a precarious threat to the neighbors would store 0.625 kWh. That’s enough for 30 minutes of typical household electricity consumption. You’ll forgive me if I ignore efficiency losses. It’s not even worth the effort. It’s over.

Flywheel Storage

Let’s put a massive spinning disk in our energy-storage “bedroom.” These might end up being popular in Malibu, as the gyroscopic stability inherent in the spun-up system could be very handy in a mudslide—keeping the house level on its way down the hill, mimicking the surfers it’s been watching all these years.

The kinetic energy stored in the rotation of a cylindrical-shaped solid disk is ¼mv², where m is the mass of the spinning cylinder and v is the velocity at the outer edge. For a fixed mass, it is better to put as much of the mass as possible on the outer edge, in a hollow cylinder (supported by spokes, for instance), which can deliver a factor of two more energy per mass. But in the case where space, not mass, is the constraint, the solid disk has more mass than the hollow version would, making it a net win to just go solid.

How big do we make this thing? Let’s give it a diameter of 2.5 m and a height of 2 m (need room for mounting, and surrounding container/structure) yielding a 10 m³ volume. At the density of steel—about 8× that of water—we get 80 tons (now even more important to reinforce that floor!).

How fast do we spin it up? Let’s pick the speed of sound—345 m/s—and see where that puts us. Go big, or go home! We get 2.4 GJ, or about 650 kWh of energy stored in this scary flywheel. That’s somewhat comparable to a similar volume of lead-acid batteries (though four times as massive). We would want to evacuate the air around the spinning disk or we will suffer a drain rate of something like 1 kW (consuming 24 kWh/day just to keep it spinning; the room would also get warm-ish).

The acceleration at the outer radius is about 10,000 times that of gravity, and it turns out the geometry and speed we picked indeed approaches the yield strength of steel. Structural weaknesses then risk breakup, which would dump the unwelcome energy equivalent of half a ton of TNT in your house. We would need to slow to a speed of 250 m/s at the outer rim to provide an adequate material safety factor, resulting in 250 kWh of storage. Another safety concern: if the flywheel comes off its support, it could barrel through the neighborhood, popping through houses like they weren’t even there. Not ideal in earthquake country.

Obviously, we can afford to scale things down a bit, since our first cut provided three weeks of storage capacity. The same cylinder spinning at 125 m/s (275 m.p.h.) at the edge gives about 90 kWh of storage, and may be somewhat more tolerable from a safety point of view. Scaling down the size/mass in addition to velocity begins to result in a less useful storage solution for the average house. If you’re going to go through the effort, expense, and sacrifice of space for a scary flywheel, you’d better feel like it provides enough energy storage to be worthwhile.

A recent $53 million flywheel storage facility in Pennsylvania uses 200 large units storing 25 kWh each, working out to $10,000 per kWh of storage capacity. Each unit’s vacuum chamber looks to be about 1.5 m in diameter and 3–4 m tall. If we raise the ceiling and squeeze four into our bedroom, we could get 3 days of electricity storage for the typical American house for a cool million bucks. But the frictional losses—while painstakingly minimized—likely preclude these units from being useful over periods of days.

Compressed Air

We could store energy in something akin to a spring by compressing air. A high-quality tank can store air at 200 atmospheres of pressure. If we make a big bedroom-sized tank in cylindrical form similar to the flywheel dimensions, it has a volume of 10 m³. The steel walls would have to be about 6 cm thick to withstand the stress, so that the tank would have a mass of approximately 12 tons. You did reinforce the floor, right?

We want to take a volume of air, V0, 200 times larger than our tank volume at atmospheric pressure (P0 = 105 Pa) and compress it to fit in the tank (adding two tons of mass!). If done slowly enough to maintain approximately constant temperature (several hours), the energy required is P0V0ln(P/P0), where ln() is the natural logarithm function. For our volume, this turns into 1 GJ, or almost 300 kWh—enough for 10 days of typical American electricity use. So we could get away with a smaller tank or simply charge it to a less extreme pressure.

The efficiency for compressing the air and later turning a turbine for electricity generation may be less than what one might find for a flywheel. The storage itself is not the hard part. I could go out today and get some lab-sized cylinders (~50 liters), which could store 1.5 kWh each—about like a golf-cart battery, although heavier and bulkier. But I would have a very difficult time arranging an efficient pumping and extraction/turbine system. If not for that, I would find compressed air to be an attractive system compared to batteries: minimal maintenance; no apparent cycle limitations, reasonably low-tech, and perfectly tolerant of remaining at low charge indefinitely.

Laboratories that frequently use compressed gas cylinders have strict safety protocols to prevent explosions from structural rupture due to mishandling. If houses across the land had high pressure vessels in various states of neglect/corrosion, we’d get the occasional boom. I might worry about having a gun in the house. But I’m guessing that house fires would still represent a bigger net threat.

Hydrogen Fuel Cell

What about electrolysis of water into hydrogen for later use either in fuel cells or combustion engines? I’ll ignore the combustion option, as the heat engine efficiency would be abysmal compared to the other storage options on the table. Batteries, gravitational storage, and flywheels can achieve better than 80% round-trip efficiency. Compressed air is harder for me to evaluate, lacking adequate knowledge on compression/extraction devices built for efficiency.

Electrolysis for the production of hydrogen tends to range between 50–70% efficient. Then the fuel cell converts the stored energy back into electricity at 40–60% efficiency for a round-trip efficiency of 20–40%. If you happen to want some of the waste heat, then you might boost the efficiency estimate (true for any of these storage methods, actually). But in a straight-up apples-to-apples comparison, the hydrogen method is a very lossy storage option. If it were dirt cheap and low-tech, I might be more excited about its potential, despite the poor efficiency. But since the opposite is true, I’m not revved up over hydrogen storage.

I spent some time searching for a hydrogen fuel cell that I could buy today with a rating in the 10 kW range (appropriate for a home). I saw some production models achieving efficiencies ranging from 40–53%, but never a price tag. If you have to submit a query to learn the price, you probably can’t afford it…

Other Ideas?

Have I exhausted all the possibilities? Certainly not. I picked obvious and representative techniques spanning gravitational, kinetic, spring force (in air), and chemical storage. These are the ideas that come to mind for me, each with some reasonable footprint in the panoply of relevant small-scale “solutions” often discussed. I stayed away from thermal storage because the round-trip efficiency will make hydrogen fuel cells look fabulous. I also stayed away from fossil fuels (gas generators, storing natural gas at home) for the obvious reason that we don’t generally need storage as long as we have a reliable supply of fossil fuels.

A short digression to contrast the miraculous energy density in fossil fuels: our 3 days of electricity storage at 30 kWh/day requires just 12 gallons of gasoline (1.6 cubic feet; 45 liters) burned in a 20% efficient generator (it seems like the other 80% is noise!). The Earth’s battery—a one-time gift to us—turns out to be vastly superior to any of these other “solutions” in terms of energy density and long-term storage, measured in millions of years. It will be sorely missed when it’s gone.

They’re All Hard

With the exception of the feeble gravitational storage example, each of the ideas presented here are technically challenging, expensive, and sometimes dangerous. I am left thinking that batteries look pretty good for home storage. And they already perform a key function in my household. But even the cheapest lead-acid solution is still expensive, high-maintenance, and requires replacement every few years. For $150, you get 1 kWh of storage. 500 cycles means 500 kWh of service (get about 1000 cycles if half-discharge, but still roughly the same total energy service). This comes to about $0.30/kWh, which makes it an expensive source of electricity. Even so, lead-acid is the most economic storage medium of choice for off-grid households, and loads better than no storage at all!

For short-term outages, we might get by with storage for critical functions only, like refrigeration and cooking. In a renewable-energy future, where storage must fill a larger role, the solutions are not obvious. As explained in the post on a nation-sized battery, we can’t simply scale up our trusty lead-acid, lithium, or nickel-based batteries to satisfy our current demands in a fully-renewable energy scenario because of resource limitations. Large-scale pumped storage, subterranean (or underwater) compressed air, and sodium-sulfur batteries may become important players. But these don’t help the independent spirit who wants personal storage, and by now is perhaps feeling—well—powerless.

The Easy Path: Ratchet Down

Many of the difficulties explored here become immediately easier with a simple reduction of scale. Because my household only uses 5 kWh of electricity per day, the 7 kWh of lead-acid storage I have in the form of four golf-cart batteries is enough to provide a meaningful service.

For me, the lesson is that adequate storage appears at first-blush to border on impossible under the current profile of consumption in the U.S. But cut consumption down by a factor of five or so, and I become optimistic. Such deep cuts are not impossible: I can personally still participate in a western lifestyle at a fifth of the energy cost at home. It’s a choice, and I’m happy with mine.

Got Storage? How hard can it be?......They're all hard......The easy path.....

The Techno-optimist's answer:

I must begin by asserting that hardly any research and development has been done at all in energy storage media. The little that has been done by auto manufacturers is merely a cosmetic show for the purpose of giving their customers the false impression that they actually care for the environment. Fuel cells and batteries are old and lazy solutions which were seized upon merely because they lay close at hand. Otherwise almost no intellectual energy, let alone money, has been expended on the problem. But one must have a rather fossilized mind to think that storage technology will remain stagnant in the primitive condition it is currently in even when hard times fall upon man and compel him to think or die. Remember Fritz Haber, a German physicist, who invented a way to create ammonia (which incidentally stores A LOT of energy), and did so when Germany was under the intense pressure of war? Remember Werner von braun, an aristocratic soul who single-mindedly (and rather belatedly) conceived of the rocket at a time when his German people were on the verge of defeat? If he had developed and refined it BEFORE Germany went to war, you and I would be speaking German, doing slave labour and never once troubling our souls with thoughts about global catastrophes. But the point is this: If there is one law of modern technological history, it is that desperate times like war or impending famine somehow bring people's minds to life and ideas flourish with an unprecedented superabundance. Right now, almost no one except a few perceptive souls actually understand the gravity of man's predicament. No one actually FEELS any pain. No one FEELS peak oil, climate change, species extinction or imminent human extinction. But when any problem finally does come vividly into the consciousness of the general population, and people do start to feel pain, and when they finally have a strong enough stimulus to think imaginatively, think of what man will create.

The design problem can be stated thus:
- Can a medium be created which will store energy and occupy as little space as possible, and be as versatile and easy to transport and to handle as petroleum is? Hec, why not do several notches better than petroleum and create a storage medium which is 1000 times as dense as petroleum? This will be a problem for the chemists and physicists.
- Do it's constituent elements exist in great abundance so that the raw material for it will be easy to obtain?

I can definitely imagine that a future human race with enhanced intellectual powers and with the aid of artificial intelligence, and most importantly with great breakthroughs in atomic physics, can conceive of such a form of matter. Next comes energy itself. I concede that the holy grail of fusion may perhaps be out of our reach given its extraordinary complexity. But I can envision satellites being deployed into space and capturing solar energy in much higher intensity and converting it into the aforementioned form of matter from its elements. This and many other ideas which are beyond the reach of our currently feeble and unimaginative intellects will surely become a reality in the future. I say this with confidence because the future will be a time when Necessity truly becomes the mother of invention, or when War truly becomes the Father of All Things (as Heraclitus once said).

So in conclusion, what we really need is not so much a new invention as some catastrophe to awaken our minds, to goad us out of complacence. Peace and plenty put the mind to sleep, and the human spirit becomes decadent. Fear and war bring the mind to life, and the human spirit resurrects its dormant powers. The men of Ancient Sparta knew this, and someday, so will we.

Glad to know I can rest easy, and that because nebulous solutions can be imagined, we can consider it a done deal. (Perhaps that's another form of mental laziness: no actual solutions proposed, for instance.) I hope you're right, but civilizations have failed the test before, despite engaged minds. Hoping we'll find something 1000x better than oil is little solace when currently we are not able to even do as well—and this against a backdrop of considerable technical expertise and attention that was comparatively nascent in Haber's or von Braun's time.


You can rest easy my friend ;)

I propose no solutions, but only reason for optimism. I bring you some thoughts about how much farther we might see once we have made intellectual supergiants of ourselves.

And there's no need to worry about mental laziness. In just 50-100 years, men will have flawless supercomputing memory chips implanted into their brains so that they will be able to think with unheard of clarity, depth, concentration and continuity, and will not be plagued with laziness, forgetfulness, headache, drowsiness, memory overload and other present day mental maladies. Like Neo from the Matrix, we shall be able to download knowledge in an instant. And I assure you, with such intellectual power, the "nebulous" solutions will virtually leap into our minds.

Civilizations have indeed failed the test. They have gone under.....And then been Resurrected. On the other hand, such a failure may be salutary. For our civilization has cramped the life of the individual. The individual matters most of all. Once the individual has been freed from the overlordship of civilization and the world is spread out into small villages, perhaps the mind will flourish again like it did in the Ancient Greek poleis.

It's important to remember that we don't need new tech: the tech we have is more than good enough.

The Prius was cheaper than a comparable ICE vehicle when gas was at $3. The Nissan Leaf is cheaper than a Sentra, over it's full lifecycle. A Chevy Volt is cheaper than a Cruze, over it's full lifecycle. Of course, consumers don't weight operating savings properly, and they're a little nervous about new tech, but the new tech is still cheaper.

Really, it is.

I must begin by asserting that hardly any research and development has been done at all in energy storage media.

Really? REALLY? From what I see, there has been a huge amount of R&D in energy storage since devices that rely upon energy storage are amazingly popular these days. I'm sure you have one if not several: Cell phones, laptop computer systems, tablet computers, portable video game devices, small GPS navigation systems, MP3 players, portable video players, etc.

And they have achieved some great results. I bet your cell phone doesn't look like this:

We all want better batteries . . . but we need to appreciate what science and engineering has accomplished for us.


It was not such a giant leap to get from a battery the size of a brick to a battery the size of a plum. In fact, the small electrochemical battery is still a battery and it is reaching the limit of its compactness. But the electrochemical battery is almost 200 years old!! Like many things invented long time ago, all that has happened in the way of innovation is further refinement and improvement in efficiency. The IC engine and Jet Engine, for example, have almost reached the limit of their efficiency. What we wish to achieve in replacing oil is a great deal more challenging. The material must be be literally invented, and this invention must be of the same order as the invention of the very first jet engine, or flight, or electricity - in other words, it doesn't yet exist at all. Before there was electricity, there was nothing akin to it. Similarly, there is now nothing akin to what will exist as an energy storage medium in the future.

The laws of physics are not changing. Nor the laws of thermodynamics. Those provide severe constraints on things that dreamers don't have to be bound by.

It was not such a giant leap to get from a battery the size of a brick to a battery the size of a plum. In fact, the small electrochemical battery is still a battery and it is reaching the limit of its compactness.

Do you actually have more PROOF for this or is this just more "faith"?

Because the batteries in that brick phone are not just a smaller version of the ones in the Android G1 developer model.

*(about halfway through, the propeller folds back and you're just gliding..)

I have to think this represents a few giant leaps, not the least of which is Power Density in the Batteries. A self-lifted RC Glider with a Video Recording of its flight.. yes, the amazing lightness of video sensors and data storage tech is ALSO central to making this possible today.. but LiPo and LIFEPO batts have helped a number of technologies cross the threshholds into viability.

LiFE PO's running Ebikes are another gamechanger.. it's just going to take a while for the considerable inertia of our Century-long Gas Habit to get eroded and unseated..

Hear hear.

An absolute mountain of R&D has been done on trying to find a better battery, over the past 30 years at least. Some of the best minds in that time have spent years trying to find better solutions.

It's partly because of that that I don't think we are going to find a miracle solution in the next 20. Just about every potential avenue of research has been mined, but either efficiency or cost, or power density, scuppers all of them beyond the x1 or x2 improvements.

We go to war with the weapons we have.

Yeah, too many people have an unrealistic view of science and technology and don't seem to understand the limits.

Pull out that Periodic table folks . . . we are already working with the lightest metal in the universe for batteries. It is hard to improve on that. Perhaps a breakthrough with a Lithium-air battery. But what we have right now can do the job . . . we just need to get the costs lower.

too many people have an unrealistic view of science and technology

That false view probably arises from the topsy turvy (upside down) rules of semiconductor technology where, strangely, small is big.

In most normal technologies (like energy storage/ generation): small is small.
A small battery is a small energy source. Period.
A small Photovoltaic (PV) panel is a small power panel. Period.

However, in the strange land of iPhones, iPads and other such game playing, informational technologies a temporary illusion is created that "technology" is marching forever forward by making things (transistors) smaller and smaller.

Indeed. People seem to think we can do anything because of what we have achieved with digital electronics. But with digital electronics, all we are implementing is data/information. Data has no inherent mass or size . . . so as long as we can reliably continue to represent the data, we can make it smaller and smaller and smaller. Thus, with shrinking transistors and magnetic representations, we have been able to represent more information and process it faster.

But in the real world, the amount of energy it takes to move a person around is not changing.

I dunno - going from 10MPG average in the 60's to 21MPG average (in the US) is real progress.

So is going to 50MPG with a Prius, and 100MPG (equivalent) with a Leaf or a Volt.

Yeah, too many people have an unrealistic view of science and technology and don't seem to understand the limits.


The only limit to technology is science. The only "limit" to science is the extent to which we have deciphered the laws of nature and the laws of the universe. With each new law that we discover and translate into our language, those limits are expanded. Therefore, I can assure you that in 1000 years (assuming that we don't go extinct before then) the "limits of science and technology" will be vastly greater than what they are now. Hec, in 50-100 years they will be enormously greater than what they are now.

We currently have "limits" to our energy usage. This is because we only know how to harness energy from fossil fuels, radioactive matter, moving water, wind, solar etc. I believe that all the current methods are fundamentally crude and primitive. Man in a conqueror and aspires to reach the other planets and eventually the stars. For that he will need an energy source which is thousands or millions of times more powerful per unit mass than anything that currently exists. But what TRULY limits his attainment of this elixir is that NO ONE ACTUALLY KNOWS WHAT ENERGY IS.

Let me digress into what I think is an apt metaphor. A long time ago, guano, bird dropping which is rich in nitrates, was a highly sought after commodity. On the coast of Chile there used to be enormous deposits of guano made by large flocks of seagulls. Would you believe that the Spanish colonists fought fierce wars for access to these deposits? Back then, chemistry was not a well developed field and the only way one could access nitrogen rich fertilizer was with bird droppings. The nation of Peru also had large deposits of guano, and they experienced what is known as "The Guano Era:"

The Guano Era refers to a period of stability and prosperity in Peru during the mid-19th century. It was sustained on the substantial revenues generated by the export of guano....

  • Doesn't this sound an awful lot like the Middle Eastern countries of the present day, having an bonanza from extracting oil made by nature?

    Would it not have been ludicrous if man had chosen to remain hopelessly addicted to bird shit, if the field of physics and chemistry had remained stagnant, so that today, we would be factory farming seagulls in order to get them to produce as much excrement as possible so that we could make fertilizer out of it? Imagine if we had a bird-shit based economy! Imagine Daniel Yergin writing a book called "The Prize: The Epic Quest for Bird Shit, Money and Power." Imagine the US invading Peru and Chile because it decided those countries needed a regime change, and all of it for what?....Bird shit!!!!! But physics and chemistry progressed, an element called nitrogen was discovered, and Fritz Haber created a way to fix it into ammonia in the early 1900's. From then onwards, guano was a relic of the past. Now that man understood that the essence of guano was a thing called nitrogen, and that nitrogen could be fixed in ammonia, which can be produced in seemingly limitless quantities, his limits were VASTLY expanded in comparison to what they were before. The key to his success was DEPTH OF UNDERSTANDING.

    In the present time, man does not understand what energy is, just as he did not understand what the potent essence of guano was. Therefore he has to harvest it from crude sources such as coal, oil, even the sun, just as in the past, nitrates could only he harvested from guano. Man knows that if a fire burns, "energy" is released in the form of heat. When water runs, "energy" can be harnessed in the form of kinetic energy. He even knows that at the atomic level, energy somehow transmutes into matter. But what "energy" is, he still does not know. For this, he will need eyes which can peer into "photons," electrons and neutrons.

    Therefore, the true HOLY GRAIL of energy is to define exactly what energy is. Once man understands what energy actually is, and can understand it in his own language, then the limits of science and technology will be fantastically expanded. No longer will man be dependent on the energy equivalent of guano - coal, oil, natural gas etc. He will know what energy truly is and will be able to make it himself.

    Let me guess. Not a scientist or engineer, are you?

    I'll let you into a little secret. There is very rarely something that TOTALLY OVERTURNS EVERYTHING YOU KNEW BEFORE, etc. etc. In general new knowledge puts a little kink, a special case or two, on top of what was known before. And generally is an order of magnitude harder to understand. And several orders more expensive.

    As such you shouldn't get your hope up for the superbattery - 1000x more storage, half the size and as cheap as corn flakes. It would be one hell of a 'special' niche case on the basics of energy storage, energy creation and what we know at the moment - which has been mapped fairly well.

    You especially shouldn't expect it in the next twenty years, in a scale that could make a difference. To be there then, it would have to be on the bench now. And there is NO sign, honest.

    Well, there is stuff on the bench that indicates 10X may be possible and there seem to be a lot of people working on those ideas.


    Like this, announced today?

    Researchers from the National University of Singapore's Nanoscience and Nanotechnology Initiative (NUSNNI) have developed what they claim to be the world's first energy-storage membrane, answering the need for cost-effective and environmentally friendly energy storage and delivery solutions.

    ... used a polystyrene-based polymer to deposit the soft, foldable membrane converted from organic waste which, when sandwiched between and charged by two graphite plates, can store charge at 0.2 farads per square centimetre ... cost involved in energy storage is also ... [reduced from] about US$7 to store each farad using existing technologies based on liquid electrolytes to about US$0.62 per farad.

    This annoucement is very suspect, IMHO. Graphite electrodes is not believable. Graphene is my guess as to what the research people actually intended. And as I have noted elsewhrere in this blog, no mention of breakdown voltage. EE-times is a marketing rag, not a refereed journal, etc.

    By using the term farad, they are obviously talking about some flavor of ultracapacitor. But at the atomic level, in an ultracap, the energy is efectively stored in chemical bonds, like it would be for a battery or a fuel cell. There is no reason to think you can have more storage per molecule than for these other systems, and stability of a large scale cap will probably limit your voltage to the weakest link (probably a defect). It reminds me of the extreme claims EESTOR was making a few years back. Now maybe they can build a better ultracap. That would be cool. But it wouldn't be a replacement for batteries, either in density of storage or in cost per KWhour of capacity. But, better ultracaps would have significant uses, including smoothing demand/charge spikes for batteries.

    Once man understands what energy actually is, and can understand it in his own language, then the limits of science and technology will be fantastically expanded.

    Um, ever hear of math and physics?! We know pretty darn well what energy is and we already have the language of mathematics with which to describe it. BTW its not the LIMITS OF SCIENCE that you should be concerned with but rather physical limits...

    The only limit to technology is science.


    The DMCA and even the new ACTA represent limits on technology that have nothing to do with Science!

    Therefore, the true HOLY GRAIL of energy is to define exactly what energy is

    Gosh, then that was met a long time ago.

    When Man defined units like the Watt. And later with things like E=mc^2.

    He will know what energy truly is and will be able to make it himself.

    Making matter is well beyond the Ken of Man.


    If you would kindly oblige, I insist that man does not know what energy is. And before you write my opinion off, I assure you I have had THOROUGH training in engineering, and yes I know my physics and thermodynamics.

    What is E=mc^2? I'll tell you what it is, with a metaphor:

    It says that if you apply twice as much guano, the crop yield will increase by fourfold. If you apply 4 times as much, it will increase sixteen-fold.

    What is a Watt? It means that if a current of one amp flows across two terminals separated by 1 volt, 1 Joule of work is done per second. In other words, if 5 tonnes of guano per day is shipped to the farming community, lets say 40 tons of crop will be produced.

    But what is E? What is a Joule? What is guano? We know what guano is. It's NITROGEN fixed in matter.

    But I guarantee you, we DO NOT know what energy is. We only MEASURE energy with Watts and Joules, just as we measure water in gallons. But if someone asked you what water is, it would be absurd to say that to cool an IC engine operating at a temperature of 3600 degF takes 10 liters of water per second. The volume or flowrate of water is merely a temporary transient property of water. But what IS water? Why of course, it's H2O.

    I hope you can forgive any vagueness in my metaphors. But I assure you the problem is very, very complicated. Man does NOT really know what energy IS. At the atomic level, electromagnetic waves which were once thought to have no mass are capable of altering the mass of atoms. After this was discovered in the days of Einstein, it became necessary to describe EM waves as discrete quanta or photons. It remains a mystery to this day how something that does not seem like mass is capable of adding to and subtracting from mass. But therein lies the secret, the Holy Grail. It is only at the atomic level that one will discover what energy actually IS, and how it seemingly transmutes from nothingness into matter.

    We do not wish to merely describe its superficial properties. We wish to know what it IS.

    Ask not, "Do we know what it is?" Ask, "Is it a useful concept?" Postmodern metaphysical waffling is not useful. You will never build a house out of metaphysical waffling. The concept of energy, on the other hand, builds civilizations.


    Ask not, "Do we know what it is?"

    In the witty words of one of my favorite philosophers Will Durant:

    You are as wrong as it is possible to be within the limits of one sentence.

    Referring to the guano metaphor which I described in my replies above, what you are saying is tantamount to this:

    Don't be a dreamy fool. Stop asking what guano is and get busy collecting as much of it as possible. Hark, over there!! Seize that coast, make those seagulls yours. Life rewards not thought but action. Stop wasting your time asking absurd questions and get to work, lazy bum!

    A few decades after these words were no doubt uttered by a lusty Spaniard, that lazy bum Fritz Haber studied metaphysically his entire life and fathomed a way to fix nitrogen, after which a hundred, a thousand, a million times as much "guano" could be produced. What a magnificent victory over the limitations of Nature!! But this was not Haber's only victory. He was called to duty during WW1. He could have be sent to fight in the trenches by some moron bureaucrat, to die a useless death. But instead he remained in his lab, where he fought battles of the intellect and created poison gas - more deadly than any infantryman could ever be. Here is one individual who is a magnificent testament to the infinite superiority of pure thought over utility and action.

    It is a grave mistake to put utility before understanding. It keeps us imprisoned in old and accustomed ways. Utility has its time. But understanding must precede overall. Action too has its time. But thought must keep its status as undisputed master.

    Your analogy is specious. If you think you're going to come up with an end-run around the laws of thermodynamics just by thinking real hard about what energy is, you're wasting your time.

    That's your take-away of Fritz Haber?!

    "...a magnificent testament to the infinite superiority of pure thought over utility and action..."

    His incredible amplification of the uses of Nitrogen into Nerve Gas, High Explosives, as Zyclon B, and even the perverse downsides of the overzealous application of artificial fertilizers since he brought it about.. these should serve as the ultimate warning against the fantasy of 'Pure Thought'.. when it has become so focused on a narrow goal that it permits itself to become blinded to the 'bycatch'.. the blowback, the unfortunate side-effects of the intellectual equivalent of MonoCultural Farming.

    Science is a great tool, but has shown itself to be just as dangerous when applied as an ideology, as any of the others. The 'Showers', the Trenches, and the Green Revolution.. all in one neat little basket. Ask his wife about these 'Battles of the Intellect'..

    "Neither you, Simon, nor the Fifty-thousand; nor the Romans, nor the Jews.. nor Judas, nor the Twelve, nor the Priests nor the Scribes, nor doomed Jerusalem itself.. Understand what Power is, Understand what Glory is, Understand at all..."
    ~ Jesus Christ Superstar

    artificial fertilizers since he brought it about

    The urban legend has that the US military used anhydrous ammonia to make the soil hard for runways - and people noticed the plant growth at the edges of the runway and thought "hey, what if it gets used on crops"?

    Did Fritz claim it was good for plants?

    Thesis and Antithesis ..

    Haber received much criticism for his involvement in the development of chemical weapons in pre-World War II Germany both from contemporaries and from modern-day scientists.[17] The research results show the ambivalence of his scientific activity: on the one hand, development of ammonia synthesis for the manufacture of explosives and of a technical process for the industrial manufacture and use of poison gas in warfare; but on the other hand, development of an industrial process without which the diet of today's humanity would not be possible.The annual world production of synthetic nitrogen fertilizer is currently more than 100 million tons. The food base of half of the current world population is based on the Haber-Bosch process.

    Gas warfare in WW I was, in a sense, the war of the chemists, with Haber pitted against French Nobel laureate chemist Victor Grignard. Regarding war and peace, Haber once said, "During peace time a scientist belongs to the World, but during war time he belongs to his country." This was an example of the ethical dilemmas facing chemists at that time.[8]

    His first wife Clara, a fellow chemist and the first woman to earn a Ph.D at the University of Breslau, committed suicide with his service revolver in their garden, possibly in response to his having personally overseen the first successful use of chlorine at the Second Battle of Ypres on 22 April 1915.[9] She shot herself in the heart on 15 May, and died in the morning. That same morning, Haber left for the Eastern Front to oversee gas release against the Russians.[10]

    What is E=mc^2? I'll tell you what it is, with a metaphor:

    Your use of 'metaphor' shows you do not actually understand.

    What is guano? We know what guano is. It's NITROGEN fixed in matter.


    guano fertilizer: fertilizer consisting of dried bird or bat droppings that is rich in nutrients, including urates, oxalates, and phosphates,

    Phosphorous. That is why guano was important.

    During the 1820s and 1830s European farmers were so desperate for ways to replenish soil nutrients that the Napoleonic battlefields of Waterloo and Austerlitz were reportedly raided to dig up bones for phosphate to spread over their fields.
    But by 1850, the Phosphorus shipped in by guano from the islands addressed the issue.

    But if you think you can show that guano mining was not historically done for Phosphorus - go ahead. Step up and prove me wrong.

    I hope you can forgive any vagueness in my metaphors.

    When one speaks in metaphors rather than clear words, one is attempting to appear as knowing when one does not.

    And you putting forth guano as being important for Nitrogen and not Phosphorous shows you do not know of what you speak. Unless digging up the bones of dead humans for the Phosphorous and being addressed by the importation of guano is a trifle not worthy of mention.

    (this ignores your ignorance that plant growth has such a tie to Nitrogen - I'm going to go for the low hanging fruit)


    Given the choice between truth and the desire to persuade, I choose truth, though it may prove me wrong. But neither you nor I are wrong about guano. It is necessary for both its nitrates and its phosphates.

    It has slightly more nitrates than phosphorous content. But historically, it was more important for its nitrates. Nitrates were used for both fertilizer and for explosives. This is why ammonia proved such an ideal replacement - it too could be used in the manufacture of explosives.

    Here is a page out of "The Origins of the Modern World" by Robert Marks, a reliable source which puts such historical developments in context:

  • Man is still very much dependent on naturally occurring ore for phosphates. He freed himself partially from the dependence on naturally occurring nitrates. (I say partially because it still requires enormous quantities of fossil energy to manufacture ammonia.) But he cannot continue this way for much longer can he? Naturally occurring material for phosphate will run out. I've seen an article or two on the subject on this site. Naturally occurring material for energy will also run out. The conclusion is inevitable. If man is going to free himself from dependence on naturally occurring materials he will have to find a way to manufacture it synthetically.

    Next, I must answer for "metaphors." Do you know that F = ma is a metaphor? Do you know that E = mc^2 is a metaphor? What is a metaphor? It is a depiction of one's experience of the world or some universal regularity in language which is intelligible to us. So for example, a savage from Melanesia who has never seen an airplane and sees it for the first time will describe it as a very large, very noisy bird. I have heard of accounts of primitive tribes in Africa who have never seen a bicycle, and who see it for the first time, calling it an "iron horse." Furthermore, metaphors provide a means with which to communicate. We conjure up shared imagery to communicate ideas. But a savage (or the average person for that matter) will not know what the concept of photon energy is, or what the speed of light is, therefore it will be quite impossible to communicate to him what E = mc^2 means until he has been given a dose of elementary physics. He must be introduced to the imagery and ideas in our minds. Likewise, I do not know how best to communicate the notion that energy has not actually been specifically defined at the elementary subatomic level, a notion that people here seem unaware of and averse to. Therefore I conjure up the imagery of guano and its history. It would appear that you hold me in contempt for such a simplistic metaphor because you are too sophisticated and find such communication lowly by your standards. But that does not mean I do not know what I am talking about. Perhaps we should start communicating in quantum physics instead? Quantum physics is after all the branch of science that deals with discrete, indivisible units of energy called quanta. Energy that is, at the subatomic level. But I know that neither you nor I will have the patience for such a mind consuming ordeal.

    Quantum physics is after all the branch of science that deals with discrete, indivisible units of energy called quanta. Energy that is, at the subatomic level. But I know that neither you nor I will have the patience for such a mind consuming ordeal.

    Hang on. Anyone who has truly had to suffer through getting their head around QM knows that the chief aspect is waves and probability distributions; not particles. Quantisation occurs through allowable eigenstates.

    As for metaphor, I don't think you understand the difference between metaphorical english and a scientific concept. Clue: one gets tested.

    I'm getting close to binning you with the green pen brigade. The unrestricted technological cornucopianism is turning into appeals to science where it appears you don't actually have any more knowledge than cod philosophy. "What is energy?" doesn't put fuel in the tank. In fact it's only useful if you follow it up with "I have this (testable) theory".

    But historically, it was more important for its nitrates.

    The phosphate rock is commercially available form is called apatite. Other deposits may be from fossilized bone or bird droppings called guano

    Give Healthy Soil with Phosphate Sea Bird Guano Fertilizers


    logo-indoguano INDOGUANO offer you Natural Ultimate Organic Fertilizer. We are producer of Phosphate Sea Bird Guano from the Indonesia. Phosphate Sea Bird Guano Indonesia is well known as a pure natural fertilizer in the world. places Guano as an important Phosphorous source

    The island of Nauru

    Extremely rich guano (accumulated bird poop) deposits were discovered in 1900 and phosphate production began in 1907. At the end of W.W. I, Australia, New Zealand and Great Britain jointly took over the island to exploit its phosphates reserves.

    Human bones ground up for Phosphorous - with the cultural taboo on disturbing the bones of the dead. But somehow the material is claimed to be MORE important for the Nitrogen.

    But read the citation to "prove" the statement mentions the multi-year accumulation of the guano.

    Then research what happens to "old guano" - as one of my links states - because it was formed so long ago, the Nitrogen is gone.

    by Robert Marks, a reliable source

    Why is he "reliable"?

    This comment has been picked over already, and I feel rather like a vulture tugging at scraps on the carcass, but I am nonetheless compelled to point out that the E = mc² analogy is wildly off: the quadratic dependence ascribed to the guano puts guano in the role of the speed of light, as this is what's squared. Energy and mass retain a linear relationship—not that this really applies to fertilizer and crop yield anyway.

    There's more to pick over - one could take up the banner that Law has or has no effect on the release of technology as mentioned in the DMCA (Digital Millennium Copyright Act) or the now signed ACTA (Anti-Counterfeiting Trade Agreement) with its new elements to the patent office as the original author claims that only science effects technology.

    Not to mention that an increase in plant fertilization as stated won't give the ^2 effect for any large selection of the volume of fertilization being squared.

    Shox is forgetting about something else. Pushing in one direction often pulls something else. More so as you reach limits. This is the underlying cause of diminishing returns.

    Would you really want to know the secret of infinite energy, if it cost all the energy on your planet to know it?


    It says that if you apply twice as much guano, the crop yield will increase by fourfold. If you apply 4 times as much, it will increase sixteen-fold.

    It would be realy nice if things worked like that...unfortunately metaphorical reality intervenes.


    What's really quite funny is the best energy storage scheme I've come across is to make ammonia (using the above mentioned haber-bosch process that ended the bird-shit crazy world), with nitrogen from the air and hydrogen produced by electrolysis using wind energy.

    I *could* put an ammonia tank next to my house and have enough fuel to heat (and power) it the entire winter. But this only works in rural areas where you can keep the tank a LONG way from the house, and probably keep the engine running on it outside as well, and pipe the power in with copper and heat in with insulated hydronic loops.

    If you've got about $4 million laying around, you can order the ammonia production part, and if you have enough money for that, you could probably afford a couple commercial ammonia fuel cells as well.

    And on a more metaphysical note, I do quite see the point in asking the question "what is energy".. And what Fritz Haber and Carl Bosch did that was not 'pure thought', but was thought followed with building pressure vessels, and watching them explode. Then thinking some more and building a slightly different pressure vessel design.

    Give me a testable thought-experiment, in plain language, like the ones Einstein proposed for relativity, about what *is* energy. The theoretical claims that we must *know* what it IS only serve to distract us from the immediate moment where we must manage what we know, and what we can observe... In other words, what is the energy-density of a particular storage media, whether that be lead-acid batteries, or ammonia.

    I'll propose a testable hypothesis: The question about what *is* energy can only be answered once the sentient beings that believe they depend on it can come to a consensus about how to responsibly and ethically use and manage it, free from coercion or control of any other sentient being. Until such time, the knowledge of what it is will remain hidden to protect the weak as well as the powerful who know not what they do.

    I really was not opposed to his raising that level of questioning.. 'What is energy?' .. but in doing so, I didn't find he was really bringing a useful point along with it.. Esoteric Thought is fine, but it's really critical to engage in a responsive exchange, and I think that was the downfall of those threads. (And has been the decline of a number of other Ex-posters here as well..)

    Ultimately, this is a social medium, and a breakdown of too many of our standard social expectations is going to fail. (IMO)
    Merely Talking AT people is one such malfunction.

    The comments here are much more civil and informative than some other sites I've seen. But yes, that did get off-tangent and neither side was willing to back down on the nitrogen/phosphate issue, which was just a lot of posturing on a side issue.

    I was expecting some discussion on perhaps zero-point energy from a vacuum, or other things not currently considered feasible (cold fusion, for instance). There very well might be some great energy source out there that we don't know about. But will it solve our problems with peak oil? Unlikely. I certainly can't plan on how to implement it into my house, which was the point of this whole article and subsequent comments.

    At a more practical level, there's a guy out there now with a fossil fuel engine that is theoretically twice (or more?) more efficient than the current ICE, is 1/4 of the weight and has fewer moving parts. But it's still in the laboratory. If it does become available, it could extend our oil economy for a decade or two longer than otherwise would happen.

    There is always "some guy" who has revolutionized the ICE. I personally think it's Bigfoot. He's smarter than most give him credit for. Why else hasn't he been found yet? Find Bigfoot, and you'll find the revolutionary ICE delivering the magic 100+ MPG. [I'm not making fun, just having fun. Please excuse the sarcasm.]

    You definitely have a point there. But this one has enough science behind it to convince ARPA-E to give him a grant (and he appeared on CNN! jk), so I had to track it down since I had forgotten the details. Apparently it doesn't have enough torque to drive a vehicle (or is variable RPM the problem?), so they intend for it to produce electricity in a series hybrid. They touting fuel efficiency improvements from 2x to 5x and lighter weight and fewer moving parts. But it's not yet in a vehicle, so we shall see.

    This reminds me of comments by Kenneth Boulding posted on ASPO USA by Dave Cohen on March 26, 2009 (at[emphasis added]. Boulding's third paragraph specifically mentioned batteries.

    A reader sent me a statement by Kenneth Boulding which I will use to put all that follows in context. Boulding was making an “individual statement” on pages 616-617 of the National Academy of Sciences study Energy in Transition, 1985-2010: Final Report of the Committee on Nuclear and Alternative Energy Systems. Remember as you read it that this was written in 1980 and it is now 19 years later.

    … The great uncertainties here are in the area of the future of human knowledge, know-how, and skill. There is a nonexistence theorem about prediction in this area, in the sense that if we could predict what we are going to know at some time in the future, we would not have to wait, for we would know it now. It is not surprising, therefore, that the great technical changes have never been anticipated, neither the development of oil and gas, nor the automobile, nor the computer.

    In preparing for the future, therefore, it is very important to have a wide range of options and to think in advance about how we are going to react to the worst cases as well as the best. The report does not quite do this. There is an underlying assumption throughout, for instance, that we will solve the problem of the development of large quantities of usable energy from constantly renewable sources, say, by 2010. Suppose, however, that in the next 50, 100, or 200 years we do not solve this problem; what then? It can hardly be doubted that there will be a deeply traumatic experience for the human race, which could well result in a catastrophe for which there is no historical parallel.

    It is a fundamental principle that we cannot discover what is not there. For nearly 100 years, for instance, there have been very high payoffs for the discovery of a cheap, light, and capacious battery for storing electricity on a large scale; we have completely failed to solve this problem. It is very hard to prove that something is impossible, but this failure at least suggests that the problem is difficult. The trouble with all permanent or long-lasting sources of energy, like the sun or the earth’s internal heat, is that they are extremely diffuse and the cost of concentrating their energy may therefore be very high. Or with a bit of luck, it may not; we cannot be sure. To face a winding down of the extraordinary explosion of economic development that followed the rise of science and the discovery of fossil fuels would require extraordinary courage and sense of community on the part of the human race, which we could develop perhaps only under conditions of high perception of extreme challenge. I hope this may never have to take place, but it seems to me we cannot rule it out of our scenarios altogether.


    Original 1980 NAS report at

    If Dave wrote this in 2009 then the article was, at that time, 29 years old, not 19. Anyway:

    There is an underlying assumption throughout, for instance, that we will solve the problem of the development of large quantities of usable energy from constantly renewable sources, say, by 2010.

    I remember reading such assumptions as near as 10 years ago. It was assumed, that once the price of crude oil got high enough then "renewables" would kick in and keep prices low. That one did not turn out too well.

    I hope most people realize by now that so-called renewables will never replace fossil fuels in either price or quantity. What we found, almost free, just lying in the ground cannot possibly be replaced by something that gleaned from the soil by farming with an extremely high input of money and energy. And you must add to that the cost to the environment and our food supply.

    Believing in renewables is a little like believing in the tooth fairy.

    Ron P.

    Seems like swinging from one extreme to the other. It is just as unreasonable to believe that technology will provide whatever we wish for as it is to believe that renewables don't constrain fossil fuel prices somewhat. Sure some people assumed the price of renewables would come down really fast. It has come down a lot, but not to fossil fuel prices yet. Maybe never to 1990s fossil fuel prices. But when we run out of fossil fuel then by definition renewables will be lower cost. Seems like you should start believing in renewables...even if they won't replace current fuels in all ways.

    It is just as unreasonable to believe that technology will provide whatever we wish for as it is to believe that renewables don't constrain fossil fuel prices somewhat.

    That is nonsense. The two are not remotely related to each other. Technology is not energy. And no one is talking about "constraining fossil fuel prices somewhat." The point made by those in the past, was that renewables will kick an and replace fossil fuels or at least not allow them to rise above a certain level because renewables would be produced cheaper.

    Of course I believe in renewables, the gas pump reminds me of it every time I fill up. "This gasoline contains less than 10% ethanol." But it neglects to tell us that this ethanol would not be there if it were not for government subsidies paying farmers to grow corn for ethanol.

    But no ethanol produced in the US has not reduced the world price of oil one whit. But ethanol does do one thing, it drives up the price of corn. This means less corn exported to third world countries and more hungry children. And palm oil production in Indonesia is driving orangutans, and a lot of other species, into extinction.

    Ron P.

    "The point made by those in the past, was that renewables will kick an and replace fossil fuels or at least not allow them to rise above a certain level because renewables would be produced cheaper."

    My quick response was probably not clear. The point above seems to me to be almost obviously true. At some point, renewables will be sufficiently cheaper than fossil fuels that they will replace fossil fuels. What else could happen when fossil fuels are running out and the sun continues to shine? The question is at what price that happens and what kind of a society can be supported with that price (which might be much higher than current fossil fuel prices). Maybe the future will have water wheels driving primitive machines or maybe it will have deserts full of photovoltaic panels, but it almost certainly will be dominated by what we now call renewables. You latch onto one of the least useful renewables in corn ethanol. If you apply 'believing in renewables is like believing in the tooth fairy' to a belief in wind generated electricity, you might see why that comment seems to me like jumping from one extreme to another.

    The point above seems to me to be almost obviously true. At some point, renewables will be sufficiently cheaper than fossil fuels that they will replace fossil fuels.

    If the price of renewable fuel is so high that people cannot afford to buy it then it is silly to say that renewables will replace fossil fuel. If you turn every acre into producing renewables with no place to grow food, then what's the point?

    My point primarily concerned quantity. We cannot possibly produce enough biofuel to replace fossil fuels. There is just not enough land on earth to replace fossil fuel with renewable fuel. The same land that is used to grow corn or sugar cane or oil palm for biofuel, can be used to grow food. As more land is cultivated for biofuel, less land is cultivated for food, and the law of supply and demand drives up the price of food.

    There was a claim during the Vietnam war that "You can't have both guns and butter". Well, you can't have both biofuel and butter.

    Of course you could take half the arable land on earth to produce biofuel, let half the people starve then you might pull it off. You would not need all that food because half the people would be dead and you would have enough biofuel for the more fortunate folks. Yeah, that's the ticket.

    Ron P.

    OK. I was just trying to reign in some of the extreme rhetoric. You clearly believe in (small amounts of) renewables in a way that is very different than a belief in (small amounts of) the tooth fairy. A livable path forward depends on careful quantitative understanding of our predicament and extreme rhetoric that is false on the face of it is not helping.

    Ganv, my point was that renewables will not save the world. We are headed for total economic collapse and that collapse will be caused, in very large part, by the decline of fossil fuel in general and liquid petroleum in particular. Call it extreme rhetoric if you desire but believing that renewables will save the world is a lot like believing in the tooth fairy.

    Catton wrote Overshoot in 1980. That was a book some might call extreme rhetoric. But every day world economics confirm that everything he wrote was true. But no one paid any attention because most, like you, believe that renewables would eventually save the day.

    David price wrote this short essay in 1995: Energy and Human Evolution. Extreme rhetoric if such a thing ever existed. But no one paid any attention because they believed that nothing that bad can really happen. Doomer porn some called it. Can't happen they said because either God, providence, technology or renewables will save us. Anyone who thinks different they say, because of their extreme rhetoric, are really not helping.

    So I guess not. Don't pay any attention to us guys who say God, providence, technology or renewables will not, in the end, save the day. Our extreme rhetoric is not helping.

    Just curious but what would help?

    Ron P.


    Thanks for the link to David Price. 16 years on we still have not learned. I agree with your view on renewables - they will not save us from the four horsemen.

    As for photons into fuel for the masses, it is at best wishful thinking. The continuing financial crisis is probably the start of Armaggedon as the giant Ponzi scheme called our banking system unwinds, even before the massive financial flows to the oil producers really begin to bite.

    Just an observation. Algae has gone quiet recently. Much less hype.
    I wonder if its a dawn of realisation.

    We don't have a disproof of the renewables will constrain fossil fuel prices. What we have is a demonstration that for a mild price increase in a short enough period of time, that they didn't have any real effect. That doesn't mean that at a much higher price point, they will. You could add PV to a hybrid car, and somewhat increase its average mpg, so at some gas price point, that starts to make sense. But, mostly until then PV and wind marginally effect demand for NG and coal, but only in the most marginal way do they effect demand for oil.

    Its really basic physics. The sort of densities required mean we have to rely upon chemical energy storage. That means we have to rely on electrochemical (batteries), or chemical storage. There has in fact been a lot of research done in these areas. One potential solution flow batteries. Another is air batteries, where one of the chemical components is Oxygen taken from the air. All of these potential solutions have drawbacks, suh as toxic materials, safety issues, like what happens if you short them. Cost issues. Lifetime issues, etc.

    So are are largely left with hydro (which can't be done at the household level), but depends upon local topography and availability of reservoirs.

    The sort of densities required mean we have to rely upon chemical energy storage. That means we have to rely on electrochemical (batteries), or chemical storage.

    Not to mention the stability of chemical storage.

    If I make a watt via the movement of a conductor through a magnetic field or via photons interacting with a semiconductor, that watt is gone by the time I type. Use it or loose it.

    I can store 80+ proof alcohol (A biological poison) for 100's of years. Propane should also store longer than a human lifespan (although I expect the container to fail 1st) Oil, be it rock or plant, can store for a number of years, as can sugar in a complex form like wood.

    Storing can lead to the impulse use of energy - be it gunpowder, a rocket, or other uses. The use and control of impulse power has moved Man forward, perhaps more than any other expression of "energy".

    Rudolph Diesel understood the harvest of dispersed energy for controlled release in his veggie oil powered engine. No longer would the farmer need the resource draining horse (you gotta feed it, comb it, take care of it on a daily basis) and the amount of land needed to feed your engine plant oil was less than the land needed to feed the horse.

    Techo. We will get AI. The problem is that it may not matter. All a hyperintelligence may tell us on certain subjects is that there is no practical solutions for certain problems.

    For example, It's possible to import hydrocarbons from Jupiter. It's not practical in any energetic or economic sense. It may never be, particularly if teleportation turns out NOT to be any kind of energetic free lunch.

    The assumption that a scalable humanlike intelligence can solve all problems in a way that matters to us as humans, even virtualized humans, is probably flawed. AI will undoubtedly improve our lot and perhaps even turn the vicinity of earth into something close to a paradisaical utopia, but even an AI will have limits. All known intelligences do.

    Remember Werner von braun, an aristocratic soul who single-mindedly (and rather belatedly) conceived of the rocket at a time when his German people were on the verge of defeat? If he had developed and refined it BEFORE Germany went to war

    Odd, very odd.  I remember that Konstantin Tsiolkovksy and Robert H. Goddard did the pioneering work in rocketry, and that von Braun's PhD thesis on rocketry was done in 1934.  He was technical director of the German army's rocket center by 1937.

    Have you, or I, suddenly wound up in an alternate reality?


    An error on my part, but not so substantial as to negate all the rest of my assertions, chief among which is that when competition - between nations, individuals and ideologies - intensifies, and vigorous individuals suddenly find themselves threatened by famine or enemies, there is a tremendous flourishing of ideas which would otherwise have remained dormant, underdeveloped or unknown. Without WW2 and later the Cold War and the space-race, von Braun would have studied Goddard and Tsiolkovsky's works as a curiosity, and written a few more papers, without ever developing the V2 and finally the NASA rocket concepts. But the situation presented itself, and suddenly, the vaguest germ of the idea sprung from image to reality on a magnificent scale.

    1300 BC -Chinese use of firework rockets becomes widespread.

    Rockets are hardly a new idea. You're acting like they were invented by one guy 85 years ago. Bologna.

    ...when competition - between nations, individuals and ideologies - intensifies, and vigorous individuals suddenly find themselves threatened by famine or enemies, there is a tremendous flourishing of ideas which would otherwise have remained dormant, underdeveloped or unknown...

    As Monbiot says in the upper right corner of the drum 'when the cheap energy is gone we will go right back to fighting like cats in a sack.' If that's what you're hoping for, you have a sick sense of optimism.


    My Cornucopian Bingo card had these squares on it:

    • No one's tried yet
    • The incentives aren't there
    • humans can solve any problem
    • Rockets!!eleven!
    • We can have something more energy dense, more versatile and safer than oil
    • we just need to go into space

    Yup, got 'em all.

    Sorry people. I just feel that this is the most appropriate response to such a ridiculous comment.

    Damn. You beat me to it.

    I was just waiting for "new paradigm".

    Perhaps the shifting to the new paradigm isn't possible because the clutch is bad?

    I must begin by asserting that hardly any research and development has been done at all in energy storage media.

    That's a fine job of asserting something.

    Got actual PROOF? Like numbers? Money spent? Money spent VS all other physical R/D and normalize it for shifts like CNC/CAD or 'nanotech'?

    Because of your weasel word of "hardly" - you may be right.

    But without actual PROOF - you are staking out a straw man.

    But the point is this: If there is one law of modern technological history, it is that desperate times like war or impending famine somehow bring people's minds to life

    That is also another fine assertion there. Calling something a "Law".

    Yes, residential storage of electricity has very few affordable options currently - basically they revolve around choosing between the different battery types, or going with a CHP unit with a propane tank (or NG if the grid is not out too long to affect pumping stations).

    This is one reason why microgrids and smart appliances are important, after significant application of conservation lifestyle techniques have been exhausted (which means few can afford a BAU PV/battery installation, nor would it be considered remotely sustainable in any regard). Of course, microgrids merely push the storage question one level up, though they also help levelize supply and demand amongst residential producer-consumers, especially when other types of producers (such as wind, pyrolysis, hydrogen storage, etc) are part of the microgrid network.

                                  AEP/CERTS Microgrid Testbed

    For those who are puzzled by the seemingly low hydro calculation, we can start with;

    Potential energy of water Ep = m*g*H
    Kinetic energy of water Ek = ½ * m *c2

    • m is mass of water (kg),
    • g is the acceleration due to gravity (9.81 m/s2),
    • H is the effective pressure head of water across the turbine (m).
    • c is the jet velocity of water at the intake of the turbine blade (m/s).

    So the potential for 22.5m3 of water is;

    1000kg/m3 x 22.5m3 = 22,500kg

    22,500kg x 9.81m/sec2 x 10m = 2,207,250 kg-m2/sec2 (Joules)

    2,207,250 Joules = .6131 kWh, which is relatively insignificant, as noted by Prof. Murphy above (scenario without losses).

    Tom, methinks you need bigger wires, if not for safety, for efficiency.

    Re: kWh storage in batteries....Usable battery storage is less than the stated Kwh (amp-hours * voltage), typically 50% - 60%. Below that point of discharge, battery voltage will drop below a usable level. Inverters will shut down, and more importantly, amperage goes up beyond the wires' rating (fire hazard or blown fuses). It also over-cycles the batteries, reducing their lifespan. Lightly cycled batteries can last years longer than the 4 - 5 years suggested in your article. My 52 Kwh rated battery bank is rarely cycled below 80% and I expect it to last 12 - 15 years (or more) with good care. A system I installed for a friend with eight golfcart batteries similar to yours just entered it's 9th year with little sign of degraded capacity. He's very frugal, electrically. More to come...

    "Tom, methinks you need bigger wires, if not for safety, for efficiency."

    Thanks for the tip. I seldom exceed 30 amps, and this only ever happens during sunshine hours when the attic fan runs AND the fridge decides to defrost (batteries barely involved in this case) so the #6 AWG can handle it. But indeed if I want to expand my PV empire, I'll be thickening up...

    I made my own as shown in this article, using 2/0 welding cable (tough and flexible) and copper pipe. After forging and soldering the lugs, I wrapped the connectors in tape and dipped the ends in plasti-coat. I expect them to outlast me. I have some suggestions to add to the article if anyone's interested.

    Woot, thanks for that. That seems a really useful way to terminate the cables.


    I'd agree with Gung and suggest that the more critical paths, at least, are changed. Change now while the price of copper is cheap :) Maybe you can pick up some short lengths cheap from a scrap yard for the jumper cables or even battery leads from a car scrap yard. Are the tags crimped or soldered? Solder would reduce resistance and protect against oxidation, use lead solder rather than tin.

    One thing that is not clear, from you photo, is if you are running 4 in series for 48V or 2x2 series/parallel for 24V. If you are running S/P then configure your end wires in a Y rather than the daisy chain that you have on the RHS. With equal paths the batteries are treated equally but the daisy chain gives an additional drop to the second bank so the first will be handling more of the load.

    Another point is that there seem to be intermediate take offs. If the load is not balanced then, again, some of the batteries will be working harder. The end result of unbalanced loading is that some batteries will die before others and you will end up with having to change out 4 batteries while some are still useful (use them in a 12V system).

    Further, there seems to be a lot of extra drop, er, I mean wire. A good cable shortening and tidying exercise seems to be in order here. Combine that with a wire upgrade and there should be a big improvement if efficiency. Put a little space between the batteries for air circulation, you seem to have a heat trap in the centre. Again, better efficiency and life.

    Interesting comparison of storage. How about the storage in the form of heat and cold? Electrical, storage room heaters and phase change material in fridges and freezers. Ice based air conditioning?


    Good point about the Y-geometry. I monitor currents on both parallel sets (2×2 configuration) and at least know that they both contribute equally. As for the extra wiring coild behind, these are not battery wiring, but go to the PV modules. Their current deployment is temporary and I will be moving them to a more profitable section of roof. Might as well keep the copper whole.

    "Another point is that there seem to be intermediate take offs."

    I call that center tapping. I have tapped my 24 volt string to provide 12VDC for some things. I use a 24/12 volt equalizer to balance the charge across the sub-strings, and as I mentioned below, I move the cells around periodically in the string. I also move the tap occasionally to the other side. Tapping is a useful tool if managed well. With my two volt cells, I can tap in 2 volt increments up to 24 volts. I've eliminated a few 'wall warts' (transformers) doing this.

    I would like to make two points in respect to cost and practicality.

    Welding lead cable bought at your local industrial supply is certainly not cheap, but it is very flexible , and insulated with a very good grade of rubberlike insulation highly resistant to abrasion, heat, and cold, etc.Standardized heavy duty plugs are are safe, fast, and easy to use.These cables and connectors meet all OSHA and other regulatory standards for use in shop and industrial and construction environments.

    How they stack up with building inspectors for permanent installation is a question I can't answer.

    But I can say this for sure;if you need heavy copper cable capable of efficiently conducting high currents at up to a hundred volts or so, there is nothing else that comes close, in terms of being able to buy it at competitive prices, locally, no shipping needed, and cut to exact length.

    The article itself is impossible to fault, in terms of thoroughness and honesty, rather than cheerleading or crying doom , with one minor quibble.My hat is off to the author.

    That quibble is that it is a common occurrence for those of us who live in the boonies to experience extended outages due to storms, forest fires, and so forth.Sometimes even those who live in major urban areas lose power due to storms too.

    As a general thing, it is not hard for most of us country guys to keep a few gallons of gasoline or diesel on hand, and the generator option is BY FAR generally the most economical option, especially if you need the generator occasionally for other uses, as I do.

    My own "goto" generator is a Big Blue(Miller) gasoline powered welder generator that can easily handle all our essential household and farm functions -including driving a 240 volt horse and a half deep well pump- for three days on thirty gallons of gasoline. By giving up all nonessential uses and running it intermittently, I could get by with ten gallons for three days.

    I don't need any inverters of other specialized equipment, either. Extension cords suffice very well, except for the well pump, electric range, and electric water heater.

    I fabricated a disconnect for the pump to isolate it from the grid by installing a double pole manual switch in the line, and putting a lock on it.I made up a length of 240 volt extension cord, which ties into the pump line with its own lockout, with the proper 240 male plug that hooks onto the pump supply wiring, and can plug that into the welder generator.

    This all cost about a hundred bucks a few years back, and took about half a day.

    We do without the electric range and electric water heater during outages.

    When we had an outage and my bedridden Mom was in a heated flotation bed, in a sunroom in August,here in the South, where "the sun knows how", that Miller kept the 12,000 ac cranking, continiously, for a day and a half, straight.

    Two rides in an ambulance to the hospital and back, and two days in the hospital would have cost as much or more than my welder generator.

    It cost three grand brand new five years ago, and I expect it to last forty years and/or eight to ten thousand hours, with some routine maintenance and repairs.

    I loaded the welder up on the truck and ran two nieghbors freexers for an hour each for them too., just in case the power didn't come back on quick enough.

    I mention these things as a PRACTICAL matter.

    AS I said, my hat is off to the author.

    As to why the bed had to be heated, it had to do with the mattress staying absolutely 100 percent bone dry, or else the very fine powder in it clumped and it quit floating her as if she were in water or quicksand.That dxxxxd bed cost forty grand, but it was worth it-no bedsores at all, once we got it.

    Yes, defiantly a good article. I've seen a few items around the net that recommend a welding generator over a normal one, same thing, that they last so much longer. I like your boonie approach to backup power, move it around and/or use extension leads. Particularly useful if you have a large property. Practical ideas are worth sharing. Thanks.



    I heartily agree with you that this was a very good article and written with humour. I liked the idea of the flywheel providing stability during the mud slide.

    Picking up on your welding generator and the 10 gallons of fuel (gasoline) lasting 3 days I thought about this.

    10 gallons is about 28 kg (sorry but metric units are easier)

    28 kg of gasoline contains (28 x 43 MJ energy) = 1204 MJ

    At 25% efficiency at the alternator that is ~300 MJ or about 100 MJ per day

    1 kWh = 3.6 MJ

    Therefore your energy demand was 27.5 kwh per day or about 1.1 kWh.

    By European standards that is quite high - about 2X average. I am not being critical but just putting it into perspective.

    The average person needs about 2500 kCal per day of nutrition. This is about 10 MJ ( I call it the 10 MJ man). Running your house for a day used the equivalent of 10 man days of work of electricity and 40 man days of work as gasoline fuel, and this was with some cutbacks. This gives us some idea of the energy density of liquid fuels and why energy storage is so difficult.

    Last year there was a BBC tv programme called the Power Station. a family unknowingly spent a weekend in a house that was powered by cyclists. A team of 80 cyclists worked in relays to power the house, without the family being aware. They operated like a normal family. The net result was that by the end of the day the cyclists were exhausted and could not keep up with the the energy demand.

    Somehow we are all going to have to do with less, a lot less. For years we have powered our economies with chemical energy which is going to prove to be impossible in the near future. Biofuels will not be an option for business as usual, and energy storage is going to be very limited. Moreover do not forget entropy. You will never get back what you have put in.

    OFM does state that he had a particular situation that required the extra power. From his other postings he does seem to run a tight ship. Also, his base load may be higher due to the farm.


    How they stack up with building inspectors for permanent installation is a question I can't answer.

    Many local building codes allow 48vDC and less to be done without inspection.

    48vDC was the standard at Telcos. I've never gotten a straight answer if Mother Bell influenced the building codes, or if Mom picked a standard the locals would ignore.

    Would that be 48V or 48V battery equivalent, ie up to 52.8V (not counting charging? If 50V is a hard break over point that may make a difference.


    You'll need to look in your local codes.

    (My memory is 90VDC and lower in my local code)

    Yes, people need to check the local code. I flagged it up in case people thought that 4 12V batteries would be ok when, in fact, they exceed 50V. Had a look in my books and can't find anything for down here, I'll have to plough through the reglamentos.


    Don't write gravity off completely. Lots of high rise hotels have rooftop swimming pools.

    Gravity can be a handy storage option; we've discussed utility scale pumped storage alot here, most municiple water systems are pressurized by gravity, at least in part, and our home's water system is solar/gravity. A small solar array runs a Sun Pump, pumping water from a spring well to a tank on the ridge above our house. Gravity does the rest; stored solar energy there, defered electrical usage.

    Speaking of utility scale storage(I know I'm getting a bit of subject here), but I've often wondered why gravity energy storage only deals with fluids. It seems like it should be possible to use solids as well. What if you used something like an electric train. You could load it up with weight and have it use electricity to go up an incline then latter have it generate electricity as it comes back down. If you had a lot of weight and a very long incline it seems like you could store quit a bit of energy this way.

    Grandfather clocks have been using gravity energy storage for hundreds of years. Again, though, weight and height severely limit this approach for anything other than minor loads.

    I can see that such a approach would be limited for home energy storage, but I'm going a little bit off subject here and talking about grid level storage. What if you had an incline that was a number of mile long? There would likely be a large height difference between the top of the incline and the bottom. Now imagine that you ran a track from the top of the incline to the bottom. On the track you used something similar to an electric train. On the way up the incline it uses electricity and on the way down in generates it. If the train weighed a lot and if the height difference between the top of the incline and the bottom was large it seems like it could store quit a lot of energy .

    Picking some arbitrary number lets say the top of the incline is 500 feet above the bottom, and lets say the train like thing weighs 20,000 tons. The stored energy when the train was at the top would be around 7,540 kWh. If you needed more then that you could add more trains storing them at the top in some kind of station. I seems like an idea like this is at least worth looking into.

    Picking some arbitrary number lets say the top of the incline is 500 feet above the bottom, and lets say the train like thing weighs 20,000 tons. The stored energy when the train was at the top would be around 7,540 kWh.

    If you have the incline, you might as well build a large tank/pool at the top and pump water. You probably won't get more cost effective with rail. Consider the cost of the rail, locomotive, wagons, 20000 tons of something, operating costs, ...

    I think you're right. On it's own it probably wouldn't prove cost effective. Although if, as bryantheresa suggested, it was used in conjunction with already existing train systems maybe that would change.

    Lets see, how about producing wheat & potash on the prairies at ~2000 ft & running it to sea level for export by ship? Oh right, we do that already. Production - done. Tracks - done. Trains - done. Electric propulsion - done. Electric braking - done. Returning all that infrastructure annually back up the hill - done.

    Overhead wires to connect to the grid - used worldwide, but not on these railroads.

    Vancouver exports
    30 million tons of coal.
    10 million tons of grain.
    10 million tons of fertilizer.

    I think that's 60 GWh of solar + geothermal powered profit (or at least it could be used to offset hauling Chinese plastic to Saskatoon WalMarts). That must be comparable to some hydroelectric stations.

    Here's to some Ferengi looking for a most profitable venture.

    I wonder how much energy is wasted by braking trains each year. Just based on the information you provided about Vancouver I'm guessing a lot. It would be worth while for someone to take the effort to preserver some of that energy. Given peak oil, all train system should probably be converted to electricity which would make preserving that energy a lot easier. I'm not really that knowledgeable about this type of thing, but I believe I've read other places on TOD that many places already use electric trains. This would seem to create an opportunity to do some fairly interesting things. If electric trains could both take and give energy to the grid(energy storage such as flywheels in key location would probably help with this exchange), and if both the electric grid and train schedulers were centrally controlled it seems like it would be possible to create a system that would help mitigate some of the problems caused by adding variable(or intermittent if you prefer) energy sources to the electric grid. I doubt if it can solve the problems by itself, but I think it could help. Though, I'm not an expert so maybe I'll find out latter that I'm completely full of it.

    You don't need fancy feed back mechanisms all you need to do is have a steep incline up into the station and a steep incline out this can effectively convert the kinetic energy into potential energy which is effectively turned into kinetic energy as the train leaves the station. This is what they do on many stations on the underground in London.

    That's a good idea, and it really should be implement wherever practical.

    It's a great idea, although I wonder about the cost of the extra digging needed: you'll need to go significantly deeper between stations to take advantage of as much gravitational potential energy as would be needed.

    Hmm, there are some potential problems.

    For one, trains are often held outside a station, waiting for the last train (and the slow passengers) to get moving. A rise up towards the station would mean crawling up the hill to the station, only to stop again.

    Second, the slope down from the station would make it difficult to stop if anything went wrong.

    Doing the back of the envelope KE=PE calcs, you end up with a delta height of ~20m for perfect energy conversion etc. Too much I think.

    What might make more sense would be a slight rise to the station (say 1-2m), with the station itself being on a gentle decline, continuing after the station. That way the train is held at the station by the equivalent of the handbrake, but PE would help break the initial resistance to motion and get the train moving again.

    Already standard procedure.

    Electric locomotives benefit from the high efficiency of electric motors, often above 90%. Additional efficiency can be gained from regenerative braking, which allows kinetic energy to be recovered during braking to put some power back on the line. Newer electric locomotives use AC motor-inverter drive systems that provide for regenerative braking.

    Oops, I guess I should have done some research before I started this Subthread.

    There is a somewhat odd proposal to move a large rock up/down a hole. The claim was that with modern mining technology that it might be feasible and affordable to do this. Another utility level idea was thermal storage, with a hot and cold tank. The later being 100s of degrees below zero C, so as to have decent carnot efficiency. But these are utility level storage, not home scale....

    Your right, it probably wouldn't be very good for home use.

    Nah, all ya gotta do is dig a deep hole, then go to the dump and scarf up a lot of unused DU ammo from all those retired M1 tanks lying around, and put that long heavy cylinder on a big pulley over the hole, and lift it up and lower it as you want to store or use energy.

    Of course you will need a hugely efficient infinitely variable transmission between pulley and alternator, but I have one of those too, if you are willing to shell out a mere couple of megabucks for a license.

    What we have here is a failure to imagine.

    If you took all the depleted uranium in the U.S. (480,000 tonnes and raised and lowered it in a 500 m deep hole (any deeper and you'll probably have trouble keeping the hole from collapsing), you get 0.6 gigawatt-hours, enough to power a small city for half an hour.


    I'm still holding out hope on breeder reactors.

    I thought we wuz talkin' about home use, I mean, like, right in my basement, where all that DU could keep me moderately warm all winter.

    Lapsing into humdrumity for a moment, I like pumped water, has millions of satisfied customers. And in time of need, you can drink it, like ethanol.

    And lots of properties are on hills or inclines.

    But unless you have a whole pond, and a quite steep drop, it is still not likely to supply very much storage.

    Really, his last point was the most important one--we have to do everything we can to minimize usage.

    Some storage can happen in the appliances themselves. If we have extremely well insulated freezers/refrigerators that open from the top so they don't loose all the cool every time you open them, and that always have 'cold storage' units in them that will thaw before other things, there is no reason that it could not keep most things cold enough for quite a long time. Really, these things should run directly on DC from solar--enough cooling should be available from sunny times to keep things cold through the rest.

    Candles are another way to store energy for lighting.

    All laptops have storage capacity, and these could be increased even as efficiency increases.

    What else is electricity needed for? Most of us could survive without watching tv for (more than) a few days.

    For energy storage in general, geothermal is a wonderful home-scaled way of storing heat in the summer to use in the winter and vice versa.

    Perhaps some of the brainiacs here could figure out how to use such geothermal storage to help on the electricity side of things?

    And why is the household level so important. Shouldn't there be block or neighborhood storage cells that could be more efficient?

    "And why is the household level so important.[?]"

    This is one area where I think doing things on a household level is useful. One can control one's own household consumption, while the neighbors (expect to) continue BAU. We do well off grid because we control our own production/consumption, and have a strong incentive to do so. Fooey on the grid weenie neighbors and their 60" plasma tvs.

    Well, I believe that an important part of future resilience will be working together, but as long as we assume that we're working against our neighbors, then yes, household-level storage makes sense.

    I don't assume I'm working against my neighbors, I just look in their driveway, or at the flood lights they leave on all night :-/

    A lot of us do work with our neighbors. I've loaned out one of my back-up generators to one neighbor as well as supplying water to another when he had trouble with his spring. People in my boondocks area do this as a natural thing to do.


    I think it's only fair to mention that this was my experience in NYC as well. There was a lot of mutual support in my street on East 62nd, tho' there were also other streets where people didn't connect as well. For me, I felt knowing as many people in my building as possible was my best security system, and there were countless other payoffs to making these friends as well.

    I was just told by someone still there in the '04 blackout that it was very similar to 9/11. People came out to the streets.. there was a lot of helping, and not a descent into fear or chaos.

    At Dancing Rabit EcoVillage, they follow a similar general strategy to the one that Tom uses in his home, but they also go with a partially collectivized organization. They use PV and an array of lead-acid batteries, and when I visited a year ago they were planning on cooperating in the installation of a large wind turbine, although that would require them to plug back into (if not draw from) the municipal grid. They certainly focus on cutting consumption, as Tom emphasizes. In addition to that, their largest storage array is in their common building, which villagers can access if they choose to belong to that co-op. There they have common areas for access to light, charging personal electronics, and electronic sound equipment, as well as a small computer lab. Many villagers do also have smaller storage solutions for their own homes, though.

    Don't write gravity off completely. Lots of high rise hotels have rooftop swimming pools.

    Gravity can indeed be useful, with the appropriate mass, height, and efficient conversion means. However, for residential storage, please see my calculation above - in most scenarios, it won't be helpful. If one has a large pond or lake nearby with a 40+ ft drop that can be converted into a hydrostorage facility (requires large pond/lake at the bottom, too), then there are possibilities.

    A hotel pool on the roof won't be able to make much of a dent in the hotel's electricity usage.

    I enjoyed reading your article. I found the part about compressed air especially interesting. In the past I considered the possibility of using 60 Gallon air Compressor for home energy storage, but at the time I had no idea how to evaluate its feasibility. Now that I’ve read your article I think I might have some clue.

    Using what I’ve learned from your article I decided to calculate how many 60 Gallon air compressors it would take to store 90 kWh. The air compressors I’m considering have a maximum pressure of 155 psi which works out to 1,068,725 Pa. That is 10.68725 atmospheres of pressure.

    Using the formula P0V0ln(P/P0)
    V0 = 2.4273385355689427992825 m^3 = ( 0.22712470799962037 m^3) ( 10.68725)
    P = 1,068,725 Pa
    P0 = 100,000 Pa
    100,000 Pa * 2.4273385355689427992825 M^3 * IN (1,068,725 Pa/100,000 Pa) = 575,049 J

    So the energy it takes to fill up a 60 Gallon air compressor is 575,049 J or around .16 kWh. If you need 90kwh for 3 days then you would need 563 air compressors. Looking on the internet I found a 155 psi 60 gallon air compressor selling for $430 dollars which means for 563 of them you would need $242,090 or $2,690 per kWr. This seems way too bulky and expensive to be practical. Good to know. Thanks for your help.

    Use a couple of 1000 gal propane tanks for storage and redo the math. BTW, if you need 90kWr for three days, you need to rethink things...

    Ok,I redid the math. I assumed 200 psi max for the tank. The tank can store 3.8 kWh. Looking on the internet I found a 1,000 gallon tank for $1600 which makes for $421 per kWh. Much more reasonable. If it lasted long enough it might be better than batteries, but in order to know for sure you would have to take efficiency into account. I don't think I really need 90kWh, but the author used that number for his calculations so I just kind of went with it.

    Right—and I use 9 times less than the number I used. I went for the typical American household usage to help illustrate how hard it will be to continue current practices in a storage scenario. If you want a truly scary number, the American 10 kW diet means 240 kWh per day of (thermal) energy!

    If the tank was well insulated, there would be some residual thermal storage there as well (heat of compression). This is usually wasted in most compressed air systems. It may also be possible to create a closed system using other gasses with different properties(CFCs?), though air is basically free ;-)

    The insulation seems like a good idea. I wonder if you could go even further and use heat from another source. I've heard of compost being used to heat water I wonder if you could use compost to heat the tank. The main problem that I can see is that you would have to be careful that it doesn't rust. A rusted tank filled with pressurized air doesn't seem safe to me. Also you would have to be careful that the heat doesn't raise the pressure over the safe limit. As for using different types of gas that seems a bit to advanced for me.

    Get a large water tank insulate it very well run a coil of high pressure tubing through the tank from the compressor too the tank. You can heat the water in the tank through a solar panel you don't have to warm the tank you only have too warm the air coming out of it to increase your efficiency

    Thanks for the suggestion, that would certainly be a lot easier and safer then heating the tank. I wonder if this could also be done by one of those solar thermal water heating devices people put on their roofs, or maybe by coiling the high pressure tubing through a "Jean Pain Mound". Both of these two methods might be somewhat more cost effective then using electricity to heat the water. Of course electricity would still be needed to fill the tanks.

    I've been looking into this idea, of and on, for a few days now. Apparently propane tanks are tested at 400 psi, but they generally operate at 100 to 200 psi. If the system could be ran at a higher psi it might be good, but I'm not sure how safe it would be. Another interesting things I learned is that water builds up in air compressors because, when air is compressed, it can't hold as much moisture. This water can be drained, but the moisture still causes rust which limits the useful life of the compressor. his leads to two questions. How much would rust limit the life of a propane tank used to store pressurized air (propane tanks used for propane seem to last a very long time), and is their any way to drain water which accumulates in a propane tank. I could maybe avoid this problem if, as Ghung suggested, I used a closed system with another type of gas, but I'm not really sure how I would go about doing that. Another interesting thing I learned is that used propane tanks can go for a lot less than new ones(yea, I know that kind of obvious). Many of them go for $1 a gallon or less. Unfortunately, none of these tanks seem to be anywhere close to where I live(I guess propane isn't popular here). Truthfully right now I don't have the money to try and do something like this anyway, but it's sill fun to dream.

    Why don't you just use second-hand compressor tanks you should be able to get them for scrap price you can tee as many as you like together start small and build up all have got water drainage vales you only need one small compressor for the lot, the size is dependant on how fast you want to charge it up. A small air motor and a second-hand dynamo and you are there

    Thanks, if I can find part for really cheep(or preferably free) I think I'll try this idea out. It would be interesting to see how well the concept really works. I'll have to look around my area and see what is available, but it might take awhile given my budget.

    Propane tanks should have a vacuum pulled on them before filing/after repair (called purging). This boils most of the condensation in the tank due to the low pressure (PV=NRT, yes?) in the tank and evacuates the 'steam'. Obviously works on any tank, it's just mandatory with propane...

    That is a good idea. If that was done to the tanks every so often they would last longer.

    I think I have a fairly good idea how this whole system might work. First you would need an air compressor. I don't think it would really need to be a big air compressor. Any 200 psi air compressor should work. I thought this one looked pretty good.

    From the air compressor the compressed air would move to a radiator. I've been giving the water problem some thought and I think the best way to deal with the problem is to keep the water from getting into the tanks in the first place. To that end the system should get as much water out of the air as possible. To do that the pressurized air would be cooled in a radiator. The radiator in this case would simply be a length of high pressure pipe. The pipe would be at a slight angle with the higher end of the pipe connecting to the propane tanks, and the low end connecting to the compressor. The lower end of the pipe would have a valve on it which could be opened to let out water when the pipe is not pressurized. Also one of these might help to get moisture out of the air. To deal with the moisture that still makes it into the tanks it would be a good idea for them to go through purging occasionally.

    Next the air would be stored in a propane tank or a number of propane tanks connected together. When the air is needed it will go from to some place where it will be heated in order to improve the systems efficiency and then it would go to make electricity. I've given some thought to how this would happen. At first I was thinking that air compressor tools could be used to turn a generator of some kind, but I think that there is a much easier way to do this.

    Looking at this diagram it seems like disconnecting the discharge tube and putting compressed air through the inlet valve would make the air pump into a compressed air engine, and the electric motor into a generator. With some modifications the same air compressor can likely be used for both compressing air and generating electricity.

    Next is the question of what to do with the electricity. There wouldn't likely be enough compressed air to keep this system running nonstop for too long a time (I haven’t actually tried to calculate this yet). In order to conserve energy a buffer would be helpful. Thinking about this two different types of buffer system occurred to me. One was a flywheel. I couldn't really find a flywheel that could be purchased to do this, so if someone wanted a flywheel they would likely have to build it themselves. The other idea is to use batteries. If someone already has a small battery system this might be a good way to expand their total amount of energy storage.

    Based on what I've learned so far I'm going to talk about what I think the advantages and disadvantages of this type of energy storage are. I've only been looking into it for a few days so I could be wrong. If so someone please correct me.

    Durability: The propane tanks in this system would probably last a lot longer than Lead–acid batteries.
    Cost: If you live in the right area you can probably pick up used propane tanks for pretty cheap. Especially if you are feeling adventurist.

    Not adventurist. $250 dollars or $263 per kWh at 200 psi.

    Somewhat adventurist. $200 dollars or $211 per kWh at 200 psi.

    Very adventurist. $100 dollars or $105 per kWh at 200 psi.


    Space: These tanks would take up a lot of space.
    Efficiency: Even with heating the gas I'm not sure if the round trip efficiency would be as good as a battery although I could be wrong.
    Location: Not everyplace is a place where people use a lot of propane, and also if you live in a suburb your neighbors might not like you doing this.

    This has been kind of a fun project so far. Thanks to all the people who have shown interest.

    Moisture in air is a very big problem, you will be increasing the partial pressure 14 times. If you have any more than 7% humidity at your inlet you will get water condensing inside the tank. We get issues in scuba and have to do some serious drying though we use a much higher pressure. You might well need some condensing and drying.

    Those tanks are usually assigned a service limit for the number of years they can be used. You really don't want old tanks especially as you do not know how they have been treated and what state they are in inside. If your 'Very Adventurist' one let go you could be in for some nasty problems that, if you were near it, might need resolving with a mop and bucket.


    Thanks for the information. In regards to condensing and drying do you know what the best way to do that is? I was thinking of something simple like running the air through a long pipe to let the air cool and release moisture, and also maybe surrounding the pipe with ice. Do you think that would be enough?

    In regards to tank life do you know how long the useful life of a propane tank is? I searched around for that information a little bit, but there were a lot of different opinions. Some people said that they had been using the same propane tanks for over 50 years. Is there some way to get a propane tank tested to see if it is still good? Also I've heard about burying propane tanks. Do you think it would be safe to use an old tank if it was buried? Sorry for all the questions. I don't really know that much about propane so I could use all the information I can get.

    Edit: I just found out about another potential problem. Residual propane in the tanks. If that isn't removed and you force a bunch of air into them it could be very bad. I'm thinking that tanks need to be purged and looked at by a professional before anything else is done with them.

    Edit again: Now I'm starting worry about people messing with old propane tanks and hurting themselves. Maybe this thread should be deleted.

    Radiator to ambient then cold water, not sure how you bleed out the water. Ice could result in icing and you use a lot more energy to create ice. You still need a water bleed in the bottom of your tank so water doesn't build up but if there is any water in there, your tank will rust through. Rusting is more aggressive at higher pressures as there is more oxygen available, that's why we inspect the inside of scuba tanks for the oxidation of the metal.

    You would have to go by current codes not what codes were 50 years ago, your code may vary. Hope those people don't get a nasty surprise, a pressure burst with a flammable gas... no I don't want to think. Burying will expose the tank to more moisture ie rust from the outside as well as from within. You would need some good construction with a largish tank. A bund may be simpler but remember Isaac when it comes to unsupported, heavy tanks at altitude.

    If you don't flush the tank first you deserve a Darwin.

    Yep, people need to take care playing with these toys, that's why I threw in a few possible issues to stimulate some thinking.


    Thank you for responding to my questions. Right now I'm feeling a lot less confident about trying anything with the ideas I've discussed. At some point I realized that turning a air pump into an air engine by disconnecting the discharge tube and putting compressed air through the inlet valve makes not sense at all. I can't figure out why I thought that was a good idea.

    Now the thinking is starting ;) Engines and compressors are similar but different. I suggest you do some googling and read up about the 2. I am not suggesting you don't play. Just suggesting you don't give someone else a mop and bucket job. There are a lot of us that try different things here but you need to appreciate the risks when you do that and plan for them. For example, if you want to play with lead acid batteries you need to pay attention to the word 'acid' and make sure you understand what is involved in handling an acid. If your cells are getting low then you need to top up by adding water but the golden rule is always add acid to water not water to acid, go figure :)


    n the Real World pressure vessels over a specific small size are regulated by law, requiring annual inspection and licencing since explosive rupturing due to a construction flaw or corrosion-induced cracking can kill and maim people (as it has in the past). Steam or compressed gases, it's the same stored energy with the possibility of rapid energy release and a resulting shrapnel field.

    Our research lab switched over from a conventional reciprocating air compressor plus reservoir tank system to a continuous-pressure vane-type compressor in part because it was cheaper to operate since the new tankless system didn't require the same levels of licencing, insurance and inspection.

    As for energy storage using compressed air, what is the EROEI (Energy Return Over Energy Injected) for such a system? Pumped-storage hydro in geographically-suitable locations returns about 65% of the injected energy but that's with short pipe runs between the upper and lower reservoirs hence low frictional losses. That's about as good as gravity-stores get and anything of suitable size (Dinorwic, Cruachan etc.) will be a major civil engineering operation to build with large upfront costs. The compressed-air storage projects I've seen mooted don't give much in the way of real numbers about the unrecoverable energy losses in the compression and regeneration processes. Only if they can match or beat that proven 65% round-trip figure for pumped-hydro are compressed-air systems likely to be considered worth building although their modularity, insensitivity to geography and lower capital investment costs per stored joule might give them an edge even with a much lower EROEI percentage.

    I looked up pressure vessel regulations and found this in the California Code of Regulations.

    (f) Air tanks having a volume of 1 1/2 cubic feet or less which have safety valves set to open at not more than 150 psi do not require permits to operate, but shall comply with all other provisions of these Orders, including construction. Air tanks used for self-contained breathing apparatus and having a volumetric capacity of 1 cubic foot or less and constructed, inspected, and maintained in accordance with DOT regulations do not require permits to operate.

    I wonder how many people in California have 60 gallon air compressors at home without permits who don't even realize they are breaking the law.

    In regards to efficiency I have no idea what it is. With all the steps involved and with loss from heat I'm guessing it's not that good, but I could be wrong. If I can find a cheep air compressor it might be fun to try and find out what kind of efficiency I can get.

    You'll find there is a drain valve in the bottom of your canary with instructions, in the manual, on how to drain the water that collects in the tank.


    Thanks, I'll be carefully to drain it regularly.

    If anyone is interested in the efficiency of air compressors this link might interest you.

    edit: Note the efficiency of air compressors has no bearing on the usefulness of CAES for grid level storage, and I'm not trying to imply it does. Also note that the usefulness (or lack thereof) of compressed air for home energy storage does not say anything meaningful about the usefulness of CAES for grid level storage, and if I accidently implied it did I apologize.

    I believe newer pumped storage can beat 80% round trip efficiency. Alan Drake reports Bath County pumped storage is 81% round trip efficient (real world #s, theoretical higher) and raccoon Mt is over 80% efficient, real world.

    CAES efficiency depends on heat capture and recovery, which can be very simple, just using gravel.

    Isentropic has designed a system that uses a "Isentropic heat pump" to store electricity in thermal form ("Pumped Heat").

    They claim:

    "The storage comprises two large containers of gravel, one hot (500C) and one cold (-150C). Electrical power is input to the machine, which compresses/expands air to (+500C) on the hot side and (-150C) on the cold side. The air is passed through the two piles of gravel where it gives up its heat/cold to the gravel. In order to regenerate the electricity, the cycle is simply reversed. The temperature difference is used to run the Isentropic machine as a heat engine.

    The round trip efficiency is over 72% - 80%. Because gravel is such a cheap and readily available material, the cost per kWh can be kept very low - $55/kWh - and $10/kWh at scale."

    Hi Nick, good to see you on TOD again!

    Your link to isentropic energy doesn;t work, try here:

    It is a very interesting, and wonderfully simple, storage scheme. It is all dependent on the efficiency of the air cycle engine, which, to date, has never been that efficient. Most industrial compressors max out at around 80% efficiency, and air motors at 50-60%. In this case the "waste heat" is not wasted at all, which is good, but I am skeptical of their round trip numbers until they have a working pilot plant.

    The great appeal of this system is that it can be put near the point of use, rather than near the point of generation, so load is added to transmission lines in off peak, and removed from them in on peak. This is something that pumped hydro generally can't do - it is normally away from load centres.
    In somewhere like southern California, the prices paid/received for peak power reflect this it is not worth much in Oregon, because you can;t get any more into Ca, but if you could do this in the LA basin, then it is very valuable.

    I'd like to see this thing pursued, but the fact that this, and other storage systems (other than pumped hydro) are not yet ready should not stop us from moving ahead with more renewables, and doing more DSM, with particular attention to "storing" the work done by off peak electricity

    As you say, many solutions we have in front of us are "good enough" , time to get going on them!

    Thanks, and yes, I agree with your comments.

    Except - I think it needs to be said that the only reason affordable forms of utility scale storage haven't been developed is that they just aren't needed yet.

    There are plenty of viable possibilities, including H2 in geological formations, or ammonia, ethanol or synthetic fuel. All could be burned in cheap thermal generators. Or, CAES would work. The fact that efficiency of all of these might be low doesn't matter because of the small scale of energy involved: 3 days per year would be less than 1% of total annual energy.

    Except - I think it needs to be said that the only reason affordable forms of utility scale storage haven't been developed is that they just aren't needed yet.

    That is generally true, but not in all areas. Southern Ca, which has sever transmission constraints, could certainly use them. But agreed, a modular, drop anywhere storage system has not had worldwide demand, until now.

    When you are talking about the three or ten day per year peaker, I don;t think you can beat a simple cycle gas turbine. Any of the other schemes require a lot iof investment, for only three or ten days of operation - they will never pay for themselves. Better to put that investment into things that will produce/get used every day of the year, IMO.

    For H2, I think the simplest way is to just produce it and add it to the natural gas pipe system. At low concentrations,5-7%, embrittlement is not a problem, and you get Hythane, which actually burns better than plain NG.

    5-7% of the NG used for electricity generation is a LOT of H2, without the expense of dedicated storage etc etc. And, like the heat system, it can be generated at the point of use, which is the NG turbine, and these can be placed in/near load centres.

    As long as the NG infrastructure is there, might as well use it. Dedicated systems can come later when the NG is too expensive.

    Excellent thoughts.

    Yes, storing H2 is very similar to storing NG, and can probably use exactly the same underground formations.

    I agree - dedicated systems can come later. Of course, I think Tom is thinking about the very long term, here.

    I wasn't actually think about putting H2 into the underground formations - you would need a lot of H2 to do that, and then it still has to be piped to wherever - not many cities have NG storage under/close to them. I was thinking that the electrolysis unit just compresses it and adds it into the pipeline system at the city end - maybe even at distribution pressure. This backs out NG at night and leaves more of it in storage to be extracted the next day. of course, this assumes the NG system isn;t approaching peak capacity like the elec grid. if it is, then we have just moved the energy from one bottleneck to another.

    What I would like to see is a designed and optimised modular home system, that emulates what Toms does. Kinda like a home sized UPS, but designed and programmed to be storing each night, and discharging each day in peak hours, to displace grid energy.

    Something that could store and discharge 12 kWh - for 1kW of continuous discharge for 12hrs. That is a nice slow charge and discharge rate for a lead acid battery.

    Combine this with some appropriate DSM measures and you could probably invert the demand curve for a typical house. Applied across a city, this would have a real effect on peak demand and transmission bottlenecks.

    Assuming, of course, the difference in peak and off peak prices justifies all this...

    In California, the differences can easily be more than 20c/kWh, (in summer) so a 12kWh swing can be $2.40/day. Most other places in the country have better managed electrical systems, so the charges are not that outrageous!

    I wasn't actually think about putting H2 into the underground formations

    Well, again, Tom is looking at the very, very distant future, when NG is very scarce. Of course, we're extremely likely to have a lot more options at that point, including much cheaper batteries, but this is a conservative approach.

    You've got a great point there - we could use "stranded wind" to produce H2 which could be injected into the current NG system - how far could this be seamlessly ramped up to replace NG?

    a designed and optimised modular home system

    Perhaps a PriUPS combined with a iPhone DSM app?

    we could use "stranded wind" to produce H2 which could be injected into the current NG system - how far could this be seamlessly ramped up to replace NG?

    I think this is better use of stranded wind than making ammonia. Going from Hythane's info it would seem up to 5% is no problem. After that, and for the high pressure lines, there may be problems with hydrogen embrittlement. BUt as I said, 5% is one hell of a lot of H2.

    Taking the idea a little further, you could do dedicated low pressure storage of H2 at an NG GT peaking plant. Since the storage does not have to be mobile, it is much easier to make, and make safe - the old style "inverted floating tanks" come to mind, as do inflatable "bags" held underwater.

    The prius thing could work, but I am looking for a dedicated house system, as in the future, I see more people going carless, especially in urban areas - which is where the worst bottlenecks are. They should not be required to have a car to do load shifting/DSM.

    A refrigerator sized box, that can sit outside any house, or on the roof of an apt building, is what I have in mind. For many apt buildings, the prius thing just won't work. BUT if the owner has a prius or equivalent then absolutely...

    Except - I think it needs to be said that the only reason affordable forms of utility scale storage haven't been developed is that they just aren't needed yet.

    That is a completely subjective assessment. It does not take into account intransigence and entrenched positions (often very profitable positions mind you) of the current energy providers, the unpaid for near fully externalized costs of fuels especially coal, and the just plain inertia that must be overcome to make a the shift to using more storage and less fuel. Tax policy can be a great tool for overcoming the above--we all most certainly trust our governments to make the most enlightened tax decisions...right.

    The economy is in rather poor shape and the current energy 'policy' or lack thereof is no small contributor to that. So my subjective assessment is that that affordable forms of utility scale storage are likely very much needed and have been for some time but our shortsightedness makes it seem they are not.

    By the way Nick I liked the response your post elicited that introduced the Prius/inverter hookup to the individual electric power backup system into the mix. That solution is so beautifully simple I would call it elegant.

    Speaking of inverters and inertia I live where an extended power outage would decimate my plumbing but I have been putting off buying a simple battery/inverter system to backup the very modest demands of my Monitor space heater (about 80w for the fans and minimal electronics) for better than a decade. I just haven't needed it yet--of course if/when I do need it will be to late to install one and my pipes will all have burst. I will remedy that--to paraphrase old Bullwinkle Moose 'This year for sure.'
    ?- )

    Please understand - I don't mean we don't need renewables yet. I strongly agree that we need to replace coal and other FFs ASAP.

    I just mean that we haven't yet implemented enough renewables to need a lot of utility-scale electrical storage.

    For the rest of your comments - I agree completely.

    Ahh, but you can convert your low watt human work via cycling to impulse power of compressed air to run an air tool for a little while.

    Pedal for 10 mins, use the air tool for a minute.

    What "we" are used to is how photons of old were converted into plants, the plants were buried and processed into what is now oil/coal. The potato you eat - it too is an expression of taking a diffused energy source and concentrating it.

    I think you are right that concentrated energy can accomplish many things that non concentrated energy can not. The simplest example of this being things like levers and knives. I don't think air compressors are useless. I'm just not sure they are the best way to store energy if your purpose is generating electricity during a black out. The 155 psi air compressor I was talked about has the energy storage complicity of about 61 AA batteries(ignoring inefficiency). While that is not useless it is probably possible to do better.

    Don't forget that the closer you get to the design limit for those compressors the lower the efficiency.


    Thanks for the thoughtful and thorough post.

    I'm reminded of a humorous sign posted on the wall of my local mechanic's shop:

    "We offer three kinds of service: Good, Fast, and Cheap. You can pick any two"

    I've often wondered of there is a similar "pick any two" matrix for battery technologies.

    In the case of batteries I think the three attributes are "Energy-dense, reliable, and cheap". In the case of home/grid storage, what we need is reliable and cheap.

    We have no problem developing reliable, energy dense batteries. I think about the Ni-H batteries on the Hubble telescope, surviving 15 years in the punishing environ of earth orbit. However they were by no means cheap. It's encouraging to see new investment in battery research going on in the automotive industry. But they miss the mark by being beholden to the energy-dense requirement.

    The mechanics sign is a version of the "infamous" engineering triangle.

    The engineering triangle goes like this, for every design, project or task there are always three variables:

    *System Requirements, i.e. performance, qualify etc. (your good)

    *Cost (your cheap)

    *Schedule (your fast)

    You can never optimize all three, they have to be balanced...

    If a bean counter comes and wants its cheaper you are supposed to ask...."what requirements are you loosening or how much more schedule are you giving me?"

    If a customer wants more features....."make it lighter and stronger cause I am a customer!" you ask for budget and schedule....

    Its a useful way to look at any project or task.

    Great article! Makes me think burning firewood is not so dumb after all and we have a really big problem going forward with present consumption...

    I fear we are going to have one hxll of a multifaceted problem burning firewood within the next couple of decades,probably sooner.

    The worst aspect will be depletion and deforestation ,the next three harvesting, processing , and transporting it efficiently.

    After that, the retrofitting of chimneys and wood fired stoves or furnaces, followed by air pollution, etc.

    I do have high hopes that community combined heat and power systems will come on strong, thereby bringing about great strides in overall efficiency.

    I also hope to be able to eventually afford a woodfired furnace with an associated steam or stirling powered electrical generator.I know that the efficiency, measured by the fuel per kilowatt hour metric, will be poor.But if I only run it when I need the heat, which is actually pretty often even in hot weather, since we are farmers and can use a lot of heat for hot water, drying crops, etc, that won't matter very much.Such systems exist already, but they are mostly custom engineered and built, and utterly unaffordable.Mass production could change that.

    I could use any excess juice from such a machine to charge up an electric car for instance, while heating the house , or feed it into the grid for credit..

    A few wheelbarrows of wood should be enough to keep the freezers properly cooled, the deep well pump running, etc, for a few hours a day, if the power goes off and there is no gasoline available for the welder.

    We have already seen the water rights to huge areas of land bought up by long term investors expecting to sell the water to nearby cities-I read about this right here on TOD iirc.

    I wonder how long it will be before we read about investors start going around buying up standing timber harvest rights a decade or two ahead from people who own tracts of forest land with substandard timber-meaning timber not suitable for lumber.

    I suspect that this might already be happening, quietly, in some parts of the country.It's very old news in some parts of the world.

    Most New England farms located close to cities a couple of centuries or so ago had hardly any trees on them- nearly all the land was cropped or pastured, and the farmer had to be pretty prosperous to be able to maintain a woodlot large enough to supply his own needs after a comfortable fashion.A lot of rural people lived in very cold houses because wood was unaffordable, or too valuable in the market place to burn more than the absolute minimum at home.

    In my grandfathers time, it was not possible to haul wood to town on a horse drawn wagon from our place and sell it at a profit. But lots of guys around here are supplementing thier income to some extent by selling firewood in town these days, using a pickup truck.I could earn a fairly respectable hourly wage- by local standards--by doing so, esprecially if I were to combine deliveries with other necessary trips to town.

    I expect to see eighteen wheelers hauling our forests away to electric power plants near Charlotte or Winston Salem and environs,if I live another decade or two.

    OFM, I know I have said this recently, but it bears repeating in this thread. I am playing around ( just that, don't have any real need for any of it, just a hobby) with an electric car (converted VW bug), 1400 watts peak PV, and an off grid fraction of my house, keeping the other fraction on the grid, totally separate.

    AND a 1kW wood fired stirling, which I snatched out of the warehouse where it had been sitting for close to 20 yrs after a failed commercialization effort. This thing is complete and ready to go, including everything. Put pellets or wood chips in, get 120VAC out. And it's actually fairly efficient- about 20% of the wood heat of combustion goes to the AC.

    So I plan to keep the car batteries up with PV and/or wood, and use them to run the fraction of house.

    What do i do when the car isn't where the house is? OMG, I hadn't thought of that.

    Actually, the purpose of this little game is to show folks around here what can be done, and also, maybe, get back at the bad guys who didn't fund that commercialization effort.

    BTW, the manufacturers cost estimate of that engine was $250, in large scale production, of course.

    OFM - That is how I see it as well, problems everywhere with energy.

    The company who builds an affordable CHP for homeowners might do well.

    A way of converting wood into electrical watts.

    And they give you the plans to make it ALL yourself - if that is something one wishes to do.

    I'm surprised the OP listed refrigeration and cooking as critical functions for electricity. Refrigeration is one of multiple food preservation methods. So the alternative to switch to another preservation method--such as canning, drying, smoking, adding salt or sugar, high heat processing, chemical preservatives.

    Likewise there are multiple ways to provide heat for cooking such as solar and wood. And of the fossil fuels coal will probably be around quite a while.

    But you also move energy from the preservation to the processing. There is also a further time element to be added for processing. Also, would you smoke a pint of milk or keep it in the refrigerator? I am not saying that there is no value in your methods but there are horses for courses. For example, canning (jars) is of no relevance to me here, they are not available in the stores. If you are able to pick up a couple of cases of them in your local market then it is a different ball game.



    Why use canning jars, just use jam jars, I use them all the time. When they are empty I just put them in the dishwasher with the lids. When they have been cleaned I just screw the lids back on and store them in the cellar. I use them for everything I usually make double or sometimes quadruple quantities when I cook. They are great for storing stews soups, etc. I made a big portion of stew last week the steak cubes were on special offer last week at the supermarket, down in the cellar six large gherkin jars, jars in a hot oven for 15 minutes filled the jars poured boiling water from the kettle over the lids and screwed the lids back on a label with date and content jobs done. I must have still 20 jars of pear sauce I made from last years harvest still in the cellar. You can even use the microwave.

    Pear sauce, yum! Yep, I do recycle jam jars in that way but I just don't get enough of them especially with a large stock of home made marmalade, to use up, in the freezer:) As I didn't have jars I used plastic containers that are readily available here but do not create a good enough seal so I put them in the freezer. It looks as is the new crop of oranges will be ready before the marmalade is used up though:(


    EDIT: Spilling.

    For those out there who do not can, a disclaimer is in order. Foods with low acid content require heating above 265 degrees (iirc - wiki/google it to be sure) in order to kill botulism spores. Otherwise, give it a couple weeks, and those popping jam-jars will be brimming with military-grade biological weapons. If you can it, and it doesn't look or smell like it did when it went into the jar, don't eat it, or peak oil is not going to be a concern for you.

    yorkshire - are you putting the whole affair in the oven or just the jar? I didn't think stew had much acid content. First time I tried canning beans (by boiling, so 212 degrees), after a couple of weeks, I had managed to fill the cupboard with a giant mess of exploded poison beans and glass. Not fun. That's my only bad experience, however. Did some reading, got a pressure cooker & mason jars (or jam jars) - does wonders after you get the hang of it.


    You missed the best known energy storage out there: fossil fuels. I could buy a diesel generator plus fuel that could provide power for 3-5-7 days for well under $1000. And if I need larger storage the incremental cost of adding more is almost negligible.
    Compare that to the figures above... a no-brainer.

    I am also a physicist and, like you, after analyzing all the options, I came to the same conclusion that golf-cart batteries represent the easiest, simplest, and most economical solution at the house-hold level for energy storage. What I would like to ask for your opinion is this: lead acid batteries don't like to be deeply discharged. If you buy deep discharge batteries they typically tolerate 50% discharge before adverse effects set in (according to the sparse info I can get). Do you think it would be sensible and/or economical to double the size of your battery bank to prolong its life significantly? As you say, deep discharge batteries give up after 500 to 1000 deep discharges. But if you make sure they're never discharged below 50% won't they last a whole lot longer? I haven't actually run the numbers on this because I haven't been able to find a decent graph that shows battery life as a function of discharges of varying degrees. (I.e., how many days of life do I get if I discharge my battery to 60% of capacity every day versus if I discharge it to 50% of capacity every day?)

    If you find the depth of discharge plot on, you'll see that you might expect 7000 cycles at 10% depth of discharge per cycle (thus 700 times the rated capacity of the battery); 3300 cycles at 20% (660×); 1150 cycles at 50% (575×); and 675 cycles at 80% (540×).

    So only 30% more lifetime juice out of a battery treated with kit gloves compared to a thrashing performance at 80% discharge. The trade-off is: fewer batteries more frequently replaced; or a monster bank that lasts 20 years. The monthly maintenance scales with battery bank size, so my calculus put me at a minimal battery bank, deeper discharge, and more frequent replacement. But I'm in a city with easy access to batteries and am grid-connected. Others will have different circumstances that may lead to different choices.

    From one of many great Homepower articles on living with batteries:

    Batteries can only supply a limited amount of energy before they are depleted. Some deep-cycle batteries may be discharged up to 80% for about 2,000 cycles, or at 50% for about 4,000 cycles. A battery-based backup power system may undergo 10 cycles per year—often less. So sizing a battery based on an 80% deep discharge rate is appropriate for this type of infrequently cycled system. (For an off-grid home that cycles batteries often daily, a more conservative approach may be necessary.)

    Once you know the desired days of autonomy, possible battery discharge level, and the energy requirements of your loads, you can size the battery. Start with the total Wh per day for backed-up loads and divide by 0.85 to correct for inverter loss (assumes an 85% efficient inverter). This results in DC Wh per day, which we will divide by our nominal battery voltage—usually 24 or 48 V (dictated by your inverter’s nominal DC input). That computes the total DC amp-hours (Ah) per day. Divide this by 0.80 to account for the maximum DOD of 80% (i.e., to leave our battery 20% full after a day of discharge). Then multiply this total by your days of autonomy to get the adjusted DC Ah total. has a good search function (some articles require membership), and Sandia Labs has done extensive research on lead-acid batteries if you can sift through their database. Lots of good stuff there.

    Also, maintenance, while not very time consuming, is critical. Sealed AGM and gel batteries are low/no maintenance but don't last as long as well maintained regular lead acid, and they cost more. For larger systems, go with big 2 or 4 volt cells (fewer cells to maintain/fail) such as 2 volt RE batteries or industrial (i.e.: forklift) batteries. Mainenance consists of periodically equalizing and topping off cells with water. Our old battery bank (Rolls/Surette 6 volt L-16) had 60 cells to maintain, our current batteries (Hawker 2200 AH, 2 volt) only have 12 cells total to keep filled/equalized. (24 volt system). I also added an automatic watering system. Regular lead acid batteries need to be vented (emit H2); not so with sealed/AGM types.

    Also, leaving lead-acid batteries in a depleted state shortens their lifespan. Keep'm charged! I top mine off at least every week, even if I have to use the generator. Folks connected to the grid shouldn't have a problem with this; set the charger to fully charge at night when watts are cheaper. Good inverter/chargers can be programed to perform these tasks automatically.

    Surprised Nickel-Iron hasn't entered the discussion yet. Don't own any myself (yet), but one of our older engineers turned me on to them. They seem to have the longevity part of the equation solved handily. Not sure about the price end - and zap I think both have pricing, perhaps someone can compare with lead-acid (I may myself when I'm on my own dime this evening) exotic raw materials either. I'm sure we can find a peak-nickel, peak-iron, and peak KOH analysis on TOD, to see how many of these we could practically stamp out...flow battery probably better at the utility scale, and I still think the economy is going DOA before we ramp up enough renewables, but there are some options for a graceful powerdown at least on a personal basis...

    non exhaustive list, btw.

    Price comparison.

    Zapp Star 1000 Nickle-Iron, 12 V, 12 kWh, $13,200
    Crown L16HC lead acid, 6 V, 395 A·hr, $304

    4 Crowns, 12 V, 9.48 kWhr: $1,216
    6 Crowns, 12 V, 14.22 kWhr: $1,824

    The Nickle-Iron batteries are 8.6 times more expensive. Ignoring amortization and the need to replace the electrolyte every 15 or 20 years, with my previous battery array of L16HC's lasting 14 years, the Zapp Star 1000 batteries are more expensive.

    A thought occurs.

    Is it possible/do people arrange for different types of battery in one home supply situation. Seems as if 1 days capacity of Ni-Fe battery would take advantage of its multiple discharge capability, whilst limiting its extra cost. You could then have Lead Acid, as a more base level - only discharged when needed, but giving cheaper capacity for the 3-4 day requirement.

    Do the varying voltage delivery aspects cause problems? I can see it would need careful control, etc. ?

    I think that suggestion is actually key, in my design philosophy.

    I like the idea of a diverse spread of interdependent parts, including the storage components.

    Practically speaking, I already have a bit of this going, where I've got bigger and smaller PV to Battery setups working independently, one for a PDA, one on Small Sealed Lead Acid for lights in the office, a larger one for an electric Scooter (under constr.) .. And a number of these cross-over with one-another.. some on a 12volt system, others (Flashlights/Portable radios) on a 4.5/5volt system, with these modular pouches of 4-Nicads that can come and go between different items.. and some adapters so that a laptop or a cell-phone could charge from the Lead Acid setup or thru USB on the 5v setup.

    Interchangable parts, and a few eggs in various baskets!

    I've been wondering if the cycles*DoD (Depth of Discharge) is more or less constant over a certain range of discharge ie the total life energy supplied is fixed. Many of the curves seem to indicate that.


    While there is variation among different batteries (types/brands), consider that the deeper one regularly discharges the batteries affects the amount of time that the batteries remain in a discharged (even partially) state. Longer discharged periods result in more complete sulfation of the cells (not good). This assumes a constant rate of discharge/recharge. Think overall average state of charge over time.

    One mistake some offgrid folks make is to oversize their battery bank compared to their PV array. If they have no other charging source (grid power, generator, etc.), they rarely get their batteries to a "hot charge" state or equalization charge, something important to the longevity of lead acids. I carefully overcharge my batteries several times a year. This causes the weaker cells to "catch up" with the stronger cells and stirs the electrolyte. Weaker cells tend to get even weaker over time with moderate use and recharging. Stirring electrolyte prevents stratification and reduces sulfation. During a good charge, I can hear the electrolyte bubbling in the batteries, a good thing as long as the cells are well covered and the H2 is safely vented. Uncovered (dry) portions of cells can/will overheat, causing a meltdown or fire. Always check that your cells are covered before equalizing, but don't overfill. Top cells off after the full charge. Use distilled or RO water.

    A cell that is using more water than the others tells me that cell may be developing a problem. I'll move that battery to a different position in the string; usually solves the problem. It's a good idea to shift the batteries around every year or two; helps keep the cells balanced. I test the individual cells at least anually with a hydrometer (after a full charge).

    These are some tips I've learned to make a battery set last much longer than most folks typically expect, part of my routine.

    Ghung, I've lived off-grid with lead-acid batteries for the past 10 years and appreciate your expert comments to round out this discussion. Add: I'm certainly not an expert in the field of off-grid electronics but have become familiar with the workings of my own equipment in its narrow range of educational opportunities. I just finished assisting a friend in town install a small auxiliary system in her grid-powered house, for emergency backup. It's wired separately from the rest of the house, accessed by a couple of dedicated outlets. The basis is 300 watts of solar panels complemented by a 400 watt wind generator for winter issues. Batteries are 4 Trojan L-16H, which are close to double the capacity of a golf cart battery. She can pretty much live off of this system indefinitely if necessary, sans electric heating appliance needs. This auxiliary power system is tun through a 1500 watt inverter to produce 120vac house current, so the usual appliances & lights can be used.

    What did you pay for the batteries?

    Nick, I don't remember what she paid for the batteries, maybe around $340 each (x 4). Pretty much the current going rate on Trojan L-16H batteries if you want to research that a bit. They're 6 volt batteries, each with 420 amp/hour capacity @ 6 volts. If you have a 12 volt system the battery bank would be 840 amp/hours gross, but as Ghung mentioned, you can't drain them all the way---a realistic estimate of storage bank size would be 50% of total rated capacity. Their life expectancy is also about double that of a golf cart battery (8-10 years vs 3-5 years for golf cart batteries).

    Have prices risen? I seem to remember Trojans going for about $90/kWh.

    Prices are still rising.

    year 2005: $76 / kWhr
    year 2011: $120 / kWhr

    Wow. Any idea why? Has quality/life gone up?

    Interesting points about swapping the cells around especially when using a centre tap. As for the sizing of the array people tend to forget that they need the power for immediate use + power for normal recharge + power for recovery charge after a cut + reserve for the not so sunny day. Thanks for the battery article too. Any thoughts on using copper pipe for buses or connections, not just for the terminations?


    "Any thoughts on using copper pipe for buses or connections, not just for the terminations?"

    Funny you should ask ;-)


    Our forklift batteries don't have threaded terminals so I had to come up with something: 3/4" type L pipe smashed flat. So far, so good. I also used copper plate for the pos/neg busses to attach my main cables for the three inverter breakers. Plenty of room to connect other stuff (I have an auxiliary 24vdc breaker panel for the trackers, battery vent fan, etc.)
    WARNING: Never use stainless for a conductor; has higher resistance and will overheat at high amps. I use stainless hardware, but not to actually conduct electricity.

    Heh, nice one, are those felt washers a big help? I needed an earth strip for a breaker box but the local stores don't sell them (whadda yer want that fer{in Spanish}). I got some copper bar, drilled and tapped it so that I could bolt on crimp eyes. Does the job. Keeping my eye open to find the local fork lift service co, not found them yet. Trojan golf cart batteries are 2x+ the price here than in the USA, Costco is about equal to USA Trojans and Autozone a little less.


    Those felt washers look like something that I have purchased at Sears for many years ( > 30y). Sears advertises that they contain chemicals that prevent corrosion built up on the terminals. For it to work the red must be on + terminal and green on -(minus) terminal. Different chemicals, I suppose. My experience is that the Sears colored felt washers really to do work as claimed. I hope these in the picture are the Sears version and not some fake.

    You might wish to look into the old Nickel Iron Batteries

    Thank you all for the plethora of information in your responses! Nickle Iron batteries look interesting and more reliable, but much more expensive. Lead-acid batteries are readily available and cheap. Now I can try and run a couple of simulations with different usages (urban backup system versus totally off-grid) and factor in the cost of the batteries. Should be relatively quick to see what the most cost-effective options are. Thanks again!

    Great article Tom and I agree completely with the take home message: "lower consumption".

    I have a longstanding question about truly off-grid power, more specifically about off-grid lighting.

    As I understand it, power is delivered to homes as alternating current because transformer losses for AC are much lower than for DC, making AC the better candidate for distributing power over long distances. (See War of the Currents for some interesting history.)

    In the kind of "resilient" home electric supply you are describing we have PV panels that produce DC, batteries that store and deliver DC and, let us assume, LEDs that use DC for lighting. Would it make sense for a "resilient" house have two sets of wiring: one for AC connection to the grid which would power appliances; and a second, entirely internal 12V wiring system for DC that ran off batteries and was used to power LED lighting and other DC devices.

    Then, even if the power went out you could at least have a well lit home. One could imagine always running the lights this way. Even when battery voltages dropped during extended cloudy periods most LEDs would still function, they'd just be dimmer. As it turns out, there is a group that already runs two sets of wiring in their living space: the RV crowd. From RV Basics: 12-Volt DC Systems:

    The basics of RV life—light, water, heat, fans and motors, refrigeration, entertainment, and safety—are provided by the 12-volt system.

    I'm thinking that running the systems listed above accounts for a lot of what we want from a home and that we really aren't that far away from having a technological solution that would keep these "energy services" up and running in an affordable, sustainable, distributed and truly resilient manner. If people accepted an RV as enough living space, how many PV panels would it take to run one off-grid? And, scaling up from there, how can we implement some of the RV solutions in a modern home who's roof is covered with PV panels? How close can we get to off-grid living with current technology?

    Sometimes I think we already have the technology we need and we just need to work on expectation management.

    Best hopes for simple, distributed systems.


    Would it make sense for a "resilient" house have two sets of wiring: one for AC connection to the grid which would power appliances; and a second, entirely internal 12V wiring system for DC that ran off batteries and was used to power LED lighting and other DC devices.

    While rare, some homes employ just this approach. It can complicate distribution a bit, with extra 'home run' lines and another subpanel, but reduces inverter losses (especially power factor) for large draw DC items such as refrigerator and well pump, as well as reducing one's exposure to the risk of an inverter failure and not having anything powered.

    115 volt LED lights are an abomination, LED are inherently low voltage, about 3V per individual dice. Separate 12V house wiring for lighting and other low power requirements makes lots of sense.

    Question for Ghung, last month you said you used off the shelf CC drivers for led's. Can I inquire as to your source?, I have 3 MR16's that the driver has gone south. I fixed 1 with a 500Ω 5W resister, not a very elegant fix.

    It may not have been me. I used some drivers salvaged from a set of LED grow lights, but try Grainger ($$$). Halifax is the goto guy on LEDs. Also, look at automotive sources, especially truck electrical parts or RV dealers. Many are going to LEDs for running and interior lighting.

    It may have been jokuhl. What I'm after is more like this:

    But a lot cheaper. Can't find the comment by searching.

    Sorry, not ringing a bell.

    I do use a number of low-volt LED's, but all are self-contained, never had to refit a driver crct.

    I've really been appreciating the sort of Low-rent SMT packages meant for the RV market that plug in like MR16's, and the adhesive Strip Lights, now that they come in Warm-White, Neutral, Cool White and Daylight.

    I've gotten a lot of interesting products from , and there are some (Surplus?) striplight deals from (around $1.75/segment when you get 10 or more segments..)

    They're not on fancy dies, as LEDs go today, but they're basic and seem very suited to simple, durable applications. (Under Counter, Car Dome Light, Nightlight, Closets, Tool Chests, Shed Light, etc..)
    These 10-led MR-11 setups have been great as desk-lights, and I have been going to goodwill and getting those Gooseneck Desk Lamps with a Transformer in them, built for like 20w Halogens, and using a 1.8 watt LED in it.. a very useful little fixture for about 2-3 bucks (the lamp is $8-15, though, so I do hope they last) - these fixtures would be easy to wire for dual use, as well, add a DC Connector and a selector switch, if you're setting your home up with both 120 and low-VDC sources. (To any not-yet-electricians, you would be connecting the Low-Volt connector and switch to the 'Lamp' end of the transformer, of course..)


    I have bought several of those 5 meter strips, (much cheaper off E-bay).

    I paid top dollar for the 9-SMT MR16's that the drivers are failing in, at

    Sorry to hear it.

    The only fails I've had from Superbright were their 'Rainbow' Nightlights, which have 5 different primary color LEDs in a Candelabra Screw base, 120 vac. They were set up to run too hot, and two have cooked on me.. ($4.95 ea)

    I've got the 10 smt Warm Whites running off of a 12v/12ah SLA batt., as my office lighting. Used these with volts up to 14.4 Nimh batts, harsh conditions (as video sungun lamps and worklights out in the weather,etc.), with no fails so far.

    I make sure to give them some breathing room, as heat seems to be the biggest hazard.


    The problem with feeding 12V around a house is the losses in the cable runs. A hundred watts of power for lighting distributed via a 12V supply needs 8 amps. On a 115V supply that 100 watts requires less than an amp. Remember losses go up as the square of the current so a 12V lighting circuit of the same length over the same type of wire (1.5mm2 twin-core plus earth, probably) will lose 60 times as much energy in the wires as a 115V supply will. The switches etc. also need to be beefier to handle the extra current.

    LED lamps used today for home lighting are usually of two types -- one is the cheap multi-LED unit with dozens or even hundreds of low-power LEDs. Careful design and series-parallel construction mean that they can be fed with "raw" 115V after simple rectification and some regulation to prevent blowouts from spikes etc.

    The other more expensive type of LED lamp uses a few high-efficiency high-output LED elements which require more careful voltage and current sources to feed them as well as active or passive cooling due to waste heat in confined areas. They could be run from a 12V supply but again since they have integral electronics to control the voltage to prevent burnout from positive temperature coefficients then it's no big deal to also design them to work with 115V AC.


    Thanks for the technical details. So what would be your favorite solution for the following problem:

    I want to live in a grid connected house with PV on the roof that may or may not feed into the grid. But I want easy (or automatic) conversion to "off-grid" mode for some minimal level of RV-style living that was powered by the PV array and some batteries in the garage.

    The starting point for this article was that off-grid mode would be used infrequently and for a maximum of three days.

    I'd like to design a house where you could be off-grid for much longer periods of time if you are willing to give up toasters and hair dryers. Ideally, you could switch to off-grid mode just to see what it would be like and then back to grid-connected mode if you got tired of it.

    It may seem silly, but it's what I want. ;-)


    That's not too silly, but it will mean making changes to the house's wiring and structure which will cost you thousands of bucks to do properly to code for safety and reliability as well as not avoiding the wrath of the local planning board. There's also the insurance situation as screwing around with the wiring in a house is a good way to have your coverage invalidated. An acquaintance of mine had that happen to him a long time back and coupled with an acrimonious divorce it resulted in him having to pay three mortgages at the same time -- one for the house that burned to the foundations which he still owed money to the bank on, one for the ex-wife to live in and another one for him to live in. He worked real hard for a decade to get out of that particular hole.

    You really need to talk to professional installers about what you want to do and how to achieve it -- it's money well spent to ensure what you get is up to code and won't kill you in your sleep. I really can't advise you from thousands of miles away, probably in a different country (my mains power is 235V 50Hz, for example) and my experience in this has been commercial setups (remotely sited radio and microwave towers and the like) more than home fitouts. It's worth noting the cost of the batteries was not the major price factor in such setups, even with regular replacements due to severe temperature cycles.

    I will say that the pics of the poster's battery setup worry me for assorted technical reasons, things like a lack of bunding around the batteries in case of acid spills or cracked battery casings. Ventilation is another worry; basically any serious battery setup should be housed in a separate building and not in a dwelling place or connected space like a garage. I'd really like to see at least one explosive gas detector head in that picture too, and ventilation ducting. The wiring is not that pretty either but others have commented on that. I presume Euan has removed the safety covers from the battery cluster to show the wiring off as dropping something large and metallic on those exposed terminals would otherwise be a bit of a disaster.

    The price of the copper for a DC system will surprise you. That is why Edison lost out to AC power. Long distant power lines are now designed to use aluminum to take advantage of the cheaper cost. In a house you have to have correct wire nuts and terminations to use aluminum otherwise you get a galvanic action.

    Professional electrician wholesalers have small power supplies that can be used for this and not expensive. Try searching on Ebay too, there are a lot of Chinese suppliers that sell them for mains and for 12V DC. From Nojay's comment below, my feeling has been that 24V or 48V is better for LED lighting but a lot of the support gear is aimed at 12V. Lower current and would be a better match for multiple LEDS.


    The LM317 IC has been around for a really long time and as such are dirt cheap.

    If you can't find them elsewhere, has a $5 fee for orders under $25, but they will sell you some.


    Thanks, but a LM317 is a voltage regulator not a constant current driver like you find inside a MR11.

    Yes it can also be used for constant current regulation, but there is no advantage over a 20 ohm resister for my purpose.

    Not to put too fine a point on it, but an LM317 is not a voltage regulator any more than it is a constant current source. It's an error amplifier and a transistor (a.k.a. a current controlled current regulator) in a nice package. What is does depends on how you connect it. *If* you have a constant voltage source already (as you seem to imply), then yes, a resistor is as good a current regulator as the 317. Follow up: I made what you are probably looking for out of an LT3756, but I know of no off-the-shelf source, unless Linear Tech is giving a really good deal on their eval kits, sorry. My materials cost was probably at least $50USD, but I wanted a 20W head & taillight for my bike, as it's my primary source of transportation and there's still alot of cars about in my neck of the woods, so I was willing to shell out. Problem is a voltage source is simple - either a transformer for AC, or a battery for DC. A switching power supply/DC-DC/buck-boost/PWM, or whatever you like to call it, on the other hand, is an engineered device, with 10-50 components, a pcb, etc. Just can't get that at wallwart+resistor-prices, as far as I've seen, even on ebay...this microcosm even seems relevant to the larger world. We have on one hand something cheap, with low efficiency, that consumes alot of resources to build (wallwart/AAA+resistor). On the other hand, we have a solution (switching LED driver) that's small, expensive, efficient, and requires a lot of economic input, technology, and supply chain to create...


    edit: not trying to sound like a jerk, just a geek, btw.

    A standard dimmer switch can be used to efficiently convert 120 VAC to low voltage DC. The dimmer switch contains a triac, which reduces the output voltage by only switching on during a portion of the AC cycle. Losses are minimal because the voltage is rapidly switched rather than throttled. Adding an RC T filter makes a cheap, reasonably efficient, sorta constant current, variable voltage DC power source.

    If you are making a fixed voltage power supply I would recommend swapping the control pot for a fixed resistor, after you get it dialed in.

    The advantage of desertrat's link is that the current will be constant from 14.2V charging to 11.2V must keep some light going. If you drive 1 LED (not 12V lamp) off a 12V battery with either a resistor or regulator+resistor you will be loosing 2.5 times as much energy as heat. Better 2 or 3 LEDs in series. Take a look on Ebay for what is available.


    I've heard this notion once before, that AC would be more efficient at transmitting electricity than DC.

    The opposite is true, and that is why really large, long-distance power lines are DC (such as the Inga-Shaba powerline across the republic of Congo).

    AC is popular because it is so easy to use - you simply transform it up or down in voltage, with simple equipment and very low losses.

    The key to low line loses is higher voltage, not the type of current, unless you are trying to cross continents.

    It's a bit more complicated than that (but I'm no expert).

    AC avoids electro-migration problems. That is where the substance of the wires, terminals, etc. physically move slowly over time because they are subject to a one-way current. While electro-migration issues are not evident in the short run they become a problem in the long run.

    On the other side of the coin, AC transmission lines are big radiating antennas that lose part of their energy as radiated away electromagnetism, even at the lowly 60 Hz frequency. That is one place where DC has the advantage.

    Bottom line is that there are tradeoffs and no utopian answer for the different problems one runs into in the real (and complex) world.

    How is that 30 kWh per day spread out over all the appliances? I don't think I -as a Western-European- have less luxury then an American, but use only 4 kWh per day and that includes electric cooking and some heavy computing now and then. There must be some very, very obvious savings possible... Even without reducing standard of living.

    The obvious savings reduce cost up to 90% and this can be reduces further significantly by only requiring the fridge/freezer and some LED-lighting to function during black-out hours. Good combi-fridges have 200+ liter space and use less then 200 kWh per year.

    If done well (reduce usage to the necessities), emergency backup could be done within a 1 kWh per day envelope. But I understand that is not where this article is about, this article is a good indicator that current American power usage and wasteful lifestyle is far from sustainable for most. Ratchet down indeed.

    "How is that 30 kWh per day spread out over all the appliances?"

    That does seem high for summer. I have an all-electric house and used 19 kwh/day last month. That includes a day a week with the 1.5 hp irrigation pump as well. Now if you have a baby and are washing diapers daily then you could go that high pretty reasonably.

    For a house to consume 30 kWhr/day, think of all the things that can be done with electricity:

    electric space heater
    air conditioner
    refrigerator / freezer
    second freezer
    electric clothes dryer
    electric water heater
    electric range
    microwave oven
    electric skillet
    incandescent light bulbs
    exterior flood lights running all night
    blow dryer
    electric dish washer (heats the water and runs the sprayer)
    electric power tools
    electric lawn mower
    water softener
    automatic sprinklers
    automatic garage door opener
    equipment that consumes power constantly even when turned off.

    The amount of wasted electricity in the U.S. is staggering some of which can be easily and less expensively replaced with other sources, such as a clothes dryer replaced with a clothes line, a dish washer with manual labor and hot water from a solar hot water system.

    electric space heater : well, there was a time where one was required for particularly cold mornings and a certain reason but it was very efficient with the thermostat, not in use now.

    air conditioner : well, heat index is in the 40s so I do use about 6kW a day, will be ending in a couple of weeks. Future plan is to run it all out on solar during the day and save the cold and lack of humidity for the night.

    refrigerator / freezer : switched to newer, more efficient one.

    second freezer : or do you mean first freezer? Planning to get one, electricity offset by raising temperature in fridge/freezer and adding insulation (can't find one with insulation in the lid around here). Extra efficiency coming from being able to prepare food in advance and freeze it, cooking 1/2 dozen portions takes little more energy than 1.

    electric clothes dryer : washing line seems to work as long as I remember to take in in before the storm or it gets a second rinse.

    electric water heater : stopped using gas when it was taking 100 pesos a month just to keep the water warm let alone what I was using. Water's warm enough to use without heating at the moment, probably get on with the solar heater in the next couple of weeks.

    electric range : gas down here, added extra insulation to the oven and slashed gas use.

    microwave oven : more efficient than warming by gas, probably build a new cookit when the rains end and use that for warming again instead.

    electric skillet : a what?

    toaster : occasionally toast over a gas ring.

    incandescent light bulbs : I may pick up a cheap 4 pack to trade them in for 4 CFLs that are being exchanged free, that will give me 4 spares.

    exterior flood lights running all night : occasionally use PIR triggered lights but I may add a few LED spots for some annoying areas.

    blow dryer : a what? At the moment I can't keep my hair dry for even 2 minutes with the heat and humidity anyway.

    electric dish washer (heats the water and runs the sprayer) : the domestica does not run on electricity

    electric power tools : please suggest how I can make holes in our local concrete without. I do use a Hilti gun for some fixings, how does that compare for energy with an electric drill?

    electric lawn mower : the chap up the road does not run on electricity.

    water softener : soft water is bad for the health. I need to get a water filter and purifier though, but there are purely pressure fed ones available.

    automatic sprinklers : 6 feet of water in August, didn't need to use my hosepipe, using it every couple of days for the pots now. The border won't get soaked with the hosepipe till December and then only monthly.

    automatic garage door opener : my hands do it automagically without electricity.

    equipment that consumes power constantly even when turned off. : Umm, off is off and I make sure of that.



    On another footnote:
    The lead battery system could be incredibly enhanced -both economic as durability- by using Nickel-Iron (NiFe) batteries. Initial investment is higher, but these are virtually indestructible and provide nearly unlimited charge cycles. They don't mind being kept at low charge levels, overcharged or frozen.

    "Buy once, replace never"

    Perhaps that's why there are hardly no battery makers providing these.

    You can learn about them here and buy them here.

    Your href didn't get posted somehow, Jonathan. Was the link supposed to point to

    Thanks NAOM. That is the one I had in mind.

    I don't know why, but when I clicked on the link to check prices, the only way I could close the page was control alt delete.

    Works fine for me. Are you on Windows, I am using Fedora/Firefox, that might be part of it. Sorry if you were inconvenienced.


    Ni-Fe, the Rodney Dangerfield of battery technology. Absolutely get Edison cells for your remote off-grid location.

    At the neighborhood level, Na-S batteries probably make sense over the long haul. No rare, poisonous, bad stuff in them.

    How about if we stop trying to plan one big central national battery to power a whole continent?

    I have no connection with Ian Soutar at but he seems to be a reliable information source for NiFe, and I think he lurks at TOD.

    Thanks! Very interesting.

    Although we do have a grid-connected PV system on our house, no electricity storage system passes a cost-benefit test for us. We lose power from ice storms in the spring every year or two, usually for hours, sometimes for days.

    With a well-insulated passive solar house, we can coast forever without freezing pipes. LED headlamps give light for hundreds of hours with a few AA batteries. A $30 inverter plugged into a car cigarette lighter plug can charge laptops and cell phones.

    Adding the cost and maintenance of batteries and/or a gas generator to avoid a few hours per year (average) of moderate inconvenience makes no economic sense.

    If our local grid becomes unstable, adding storage at a grid level will likely always make more economic sense than at a household level (however much that conflicts with the US "every man for himself" attitude and with the valiant doomer fighting off the zombie hordes meme). Pumped storage at utility scale costs about 10% of batteries at utility scale, let alone at household scale.(

    Rather than wasting money on purchasing a household storage system that will almost never be used, investing in household energy efficiency and passive/active solar give orders of magnitude better financial return on investment.

    I guess the most cost effective goes:

    1. No storage.
    2. Generator backup.
    3. Batteries.

    In that order in case of a big outage. Since most big outages seem to happen at least as regularly in every season and most PV arrays are probably best sized for maximum power relative to needs in the summer a generator would probably make the most sense. Even a 3KWA generator wouldn't be bad for keeping the lights on, the fridge going and the TV running until the power turns on if one can't possibly live without TV. (Wife).

    Are there any small batteries which would be suitable for say at most 1 hour power outages which are relatively cheap? I was thinking that one doesn't need a lot of them just enough to get the generator sorted out (if it exists).

    P.S. Theres another fringe benefit to having a generator. If the xxxx really hits the fan, you're instantly that McGyver type since you're the one was actually prepared. You can save a lot of lives with a portable generator. :-)

    Serendipity: our solar system just evolved. It's only a little bit passed the "toy" level at 400 watts name-plate. It keeps our electric bikes (2) charged and runs the night-lights.

    We have a battery bank of 6 - 12 volt gel batteries (95 ah). They came from our GEM electric car when they wouldn't any longer push it up our mile-long 10% hill but they still had (probably) 80% of their original capacity. I run the system at 24 volts. I use a 1500 watt sine inverter to run the chargers and lights.

    On the solar side all I have are three 135 watt 12 volt (nominal) panels in series controlled by a 15 amp Morningstar charge controller. We don't get much solar in Seattle but it works and will provide us with emergency power with a patch cable.

    As long as we keep the GEM we'll have a supply of batteries every three years or so.

    Some points to consider:
    Flywheels can be repeatedly rundown and runup without incident( more or less infinite discharge cycle life. I think you gave them short shrift in your analysis)- especially as a tool to buffer intermittant power supplies like wind and solar .The wheels themselves are made with composites and I don't know where you get the relatively high weights you cite. Their other strength is you get all the power you bargain for at whatever rate of discharge you need- you cannot treat a chemical battery as linear at high discharge rates- but you can discharge the whole flywheel if you need too in 5 minutes.
    Chemical batteries so far require large amounts of somewhat toxic materials to make, use and dispose of.
    Pumped storage is already used now--we have an entire resorvoir here in NJ ( Round Valley) which does this.
    In general each region will have a mix of the most appropriate and cost effective solutions- Livingston MT or Alpine Texas need nothing more than wind, and adobe plus pv and a couple of batteries work well for the southwest. and dry states.
    Most areas can cut their footprint handily by simply putting a solar hotwater tank up with a few pv panels--and if we required all houses to be oriented roofwise for easy south facing placement- we'd make a big dent right there

    Other ideas: Supercapacitors and Superconducting electromagnet.
    This is in response to request for other ideas.

    An electric capacitor stores electrical energy. For a capacitor having a capacitance, C, and charged to voltage, V, the energy E is

    E = 0.5 * C * V**2

    For an electromagnet, having magnetic inductance, L, and carrying electric current, I, the the energy stored in the magnetic field, E is

    E = 0.5 * L * I**2

    I see occasional mention of supercapacitors in investment opportunity news letters. The energy stored in large superconducting magnets is well known to the builders of elementary particle accelerators such as at FermiLab and CERN.

    I have never seen any discussion of the top voltage that can be applied to a supercapacitor, or what physical effect limits it. For supermagnetics, the limit seems to be a build up of a magnetic pressure that is manifest as an outward force on all the coils of wire. The engineering problem is building a mechanical structure that is strong enough to hold the wires in place, and also thermally insulating enough to allow maintenance of cryogenic temperature.

    The voltage limit of a capacitor is determined by the dielectric strength of the insulator.

    It's not clear why the message should be to reduce electricity use and not gas. After all gas will be gone one day (or prohibitively expensive) but 4th generation nukes could be giving plenty of power. By then we'll be using electricity for most home heating, hot water and cooking. That means doubling your PV and battery pack.

    Another issue is that of decentralised vs. central energy storage. I've seen estimates of the cost of pumped seawater storage of around 5c per kwh on top of generation and transmission costs. That's way cheaper than 30c per kwh for lead acid batteries. I guess a rejoinder to that is that there are millions of homes but few suitable sites for pumped seawater hydro. OTOH many households with badly behaved kids should not have battery packs.

    I think that people who worry and plan ahead will have electricity from their solar voltaic panels long after NG is gone. Storage of energy from PV panels will continue to be a problem so long as the Earth turns.

    When Earth stops turning there will be other, bigger problems, IMHO.

    October. Isn't it time for the E-Cat (Rossi/Focardi)?

    Why has no one mentioned NGK's NaS batteries, capable of storing 6.5 Mwh?

    Or prudent Energy's Va flow batteries that can be containerized?

    It would seem this topic needs revision.


    "Why has no one mentioned NGK's NaS batteries, capable of storing 6.5 Mwh?"

    Funny you should mention NGK and sodium-sulphur batteries...

    A 2MWh static NaS battery pack at NGK offices in Japan caught fire a couple of weeks ago. Who would have thought elemental sodium and liquid sulphur kept at 300 degrees Centigrade might catch fire?

    I've not seen any more reporting about this incident other than the TEPCO press release I referenced above. One wonders what the local fire brigade used to put the fire out with -- water is seriously contraindicated with this sort of chemistry, of course.

    Kudos, Tom, for a good article and for your efforts to promote numeracy. There's a sore need.

    My take-away is that we can't expect to see anything better than optimized lead-acid batteries anytime soon. Recycled Ni-MH or Li-ion battery packs from hybrid and EVs may soon begin to provide a better alternative, but it won't be radically better.

    But that's for storage at the level of a single home. Some options that don't look good at that level are more promising for use at the neighborhood level (i.e., distribution nodes). Even gravity power. There's a company promoting that approach: see

    The key to overcoming the weakness of gravity storage is a large height, courtesy of a 3-km deep shaft, and a very massive weight with very low specific cost. Even so, economic feasibility will depend on the development of automated machinery that can reduce the cost of excavating deep shafts.

    A technology that I like better for distribution-level energy storage uses compressed air in combination with thermal storage. Like Gravity Power's solution, it employs an excavated shaft, but gives nearly 10x the energy storage per cubic meter. I don't have a link for where one can read about it. It's one of my own pet projects, and I haven't finished a write-up that's suitable for posting.

    This is a perfectly good article, as far as it goes....but it's misleading.

    Batteries are far too expensive for use just once or twice per year: there's no way to amortize their expense over a large number of discharge cycles. In this case, energy costs, volumes and efficiency losses are unimportant: what matters is the capital cost of the system.

    So, if we want to move to intermittent renewables what we need are systems where storage is very, very cheap.

    This includes biomass: for home heating, wood (and dried hay, grass, and charcoal) are easy and cheap to store. For electricity, ethanol in a cheap (not especially efficient) generator. Biomass is limited in total annual production, but that doesn't matter, because we won't use this backup very often.

    This also includes synthetic fuel (synthesized hydrocarbons using renewable electricity to electrolyze seawater and combine H2 with atmospheric carbon), burned in a cheap generator. Synthetic fuel is perfectly doable right now, it's just expensive (maybe $10/gallon). But that expense per unit of energy consumed doesn't matter, because it won't get used much.

    For daily power shifting from day to night batteries might make a bit of sense. Li-ion at $400/kWh, 80-100% DOD and 10x the cycle life probably make more sense than $150/kWh lead-acid: if you really discharge to 80% DOD 365 times per year, you'll be replacing that lead-acid every 2-3 years, and that's expensive.

    Now, if you already have the batteries sitting around for another use, like transportation, then the capital expense isn't a problem: probably the most sensible thing is to use your extended range EV as a storage battery and generator (again, burning ethanol).

    Finally, no one should think that the same systems that make sense for a household would make sense for the grid: other methods would be much cheaper on utility scales, including modest overbuilding of generation capacity, diverse energy sources, DSM, V2G, etc, etc, etc. Biomass, synthetic fuel and electrochemical storage might be useful as well, but they would be pretty small components of the overall energy supply.

    What's even cheaper is adding an inverter to a Prius (search on PriUPS). I bought a pure-sine wave inverter, 750 watts, for my Prius in the event of a power outage. I can use it to power the fridge and a couple lights or the modem and a computer and a TV. Can't do the whole house by any means, but I just wanted a low-cost way to survive a day or so with minimal disruption. You can tap off of the main traction battery for greater than 1 KW systems, but I wanted a simpler approach, and tap off of the 12V battery (which means my amps are limited). This basically turns my Prius into a generator that is really quiet and runs a few minutes an hour (the traction battery supplies the 12V battery, and the ICE only turns on to recharge the traction battery). This is much more efficient than a stand-alone generator and you don't need another ICE around the house.

    The downside is if the outage goes on for a long time, your car is also out of gas, but I'm assuming temporary outages, not an end-of-civilization event. (Hopefully there would be some warning for that, and I can get home to my acreage in MN next to my uncle's farm - it takes a full tank of gas to get there).

    That's a great idea. It's the kind of thing I had in mind above when I said "probably the most sensible thing is to use your extended range EV as a storage battery and generator (again, burning ethanol)."

    A Prius works just great.

    In order to avoid speculation on the possibilities of storage capacity for the different type of batteries, I suggest to pay a look to the article written by Kurtz Zenz House, which is very telling, not only about present storage capacities of the most known batteries, but also the thermodynamic limits (we can hardly fight against these limits, despite of technolatry).

    And they are very, very far from being able to offer an alternative for massive energy storage.

    The title: The Limits of energy storage technology

    The link:

    Did you read my comment above?

    The maximum energy density of batteries isn't very important - they're dense enough.

    Dense enough what for?

    Did you read the article comment:

    'So the best batteries are currently getting 10 percent of a physical upper bound and 25 percent of a demonstrated bound. And given other required materials such as electrolytes, separators, current collectors, and packaging, we're unlikely to improve the energy density by more than about a factor of 2 within about 20 years. This means hydrocarbons--including both fossil carbon and biofuels--are still a factor of 10 better than the physical upper bound, and they're likely to be 25 times better than lithium batteries will ever be'

    Dense enough what for?

    Dense enough to create practical, useful, affordable transportation.

    Who cares about the theoretical energy density of fuels? We care whether our cars perform well, get us where we're going, and are affordable.

    The Prius was cheaper than a comparable ICE vehicle when gas was at $3. The Nissan Leaf is cheaper than a Sentra, over it's full lifecycle. A Chevy Volt is cheaper than a Cruze, over it's full lifecycle. Of course, consumers don't weight operating savings properly, and they're a little nervous about new tech, but the new tech is still cheaper.

    The weight of the battery is a benefit: it makes handling better.

    I do care aobut theoretical upper energy density in different type of batteries. I am amazed with the people still making calculations in dollars, when the value in dollars of a whole country can pass from zillions one day to zero or negative one year after. I am talking about physical limits, thermodynamical limits, not dollar games on chips.

    Perhaps you could explain to me where have you found the practicality, usefulness and affordability of the present electric cars. Spain had an official program (and Spain, a country consuming more or less like California, is world leader in renewable energies, with 17% of electricity demand covered by wind and 3% covered by solar PV) to manufacture and sell 20,000 electric cars for 2010, as per the renewable energies program. The balance made by the Ministry of Industry and the automotive sector (with a factory ouput capacity of 3 million cars per year and a park of 30 million private cars in a 46 million inhabitants population) was the terrific figure of....200 (two hundred!!!!) despite 7,000 $ subsidy per car, free and preferential parking in the streets and tax exemptions.

    Who cares then about your dollar per gallon comparisons?

    The balance made by the Ministry of Industry and the automotive sector (with a factory ouput capacity of 3 million cars per year and a park of 30 million private cars in a 46 million inhabitants population) was the terrific figure of....200

    I'm not familiar with that program. I think you need to investigate further. In Europe, most people drive many fewer miles than in the US, so it's harder to amortize batteries. Beyond that, I don't know.

    In the US, EVs are selling as fast as they can be made, with very, very long backorders.

    I'll grant you that hybrids aren't selling as fast as they should in the US: that's because liquid fuels are under priced: they don't include all of their costs.

    I'm not familiar with that program. I think you need to investigate further. In Europe, most people drive many fewer miles than in the US, so it's harder to amortize batteries. Beyond that, I don't know.

    Well, this is one of the most important programs in Europe and they missed the target of electric cars deployment by TWO ORDERS OF MAGNITUDE. This, despite all the incentives to the industry, which, as I have mentioned, in Spain has a capacity of 3 million units per year, which is not negligible.

    And I do not share AT ALL your opinion that more use (loner ranges in commuting) is better for anything that has to last as much as it is possible. The word "amortize" (for a price) is absolutely economicist in this context. I is a word very adequate for a consumerist world, not for thermodynamic calculations or for life cycle analysis.

    The world has an ICE cars manufacturing capacity of about 70 million units a year.

    In the US, EVs are selling as fast as they can be made, with very, very long backorders.

    This is very vague and does not prove anything. A long backorder of 10 units per year, when the manufacturing capcacity is 3 does not impress so much, does it? Figures will be appreciated. I gave you mine for a country like California in activity. If the batteries powering the EV's are dense enough now and very convenient, suitable and versatile, why the US industry has not yet turned their ICE's manufacturing capacity into electric? They are able, when they want, to change whole the production lines in one year.

    I'll grant you that hybrids aren't selling as fast as they should in the US: that's because liquid fuels are under priced: they don't include all of their costs.

    I do not buy the classic argument that EV's do not progress because the oppostion of a society maneouvering to underprice fossil fuels.

    Again, an economicist concept. What does it mean that fossil fuels are underpriced ? With respect to what? To Europe? Yes. To a just price? Who fixes 'just' prices in an eminently fossil fueled society? The economy and the industry and the financial world powered by wind energy, or solar PV or hydro or nuclear energy, for instance? (or, more sensibly is on the contrary?). How it comes that a basically fossil fueled society (over 80% is powered by fossils at world level) can underprice its very source of motion? It is like if I could subsidize or "underprice" my own breath to become more competitive.

    Only to the economy of hydrogen the EU and the US have spent several billion US$ in subsidies. Who provides this surplus of resources? Isn't a basically fossil fueled society and a basically fossil fueled economy?

    Pedro, EV production capability is just a couple times 10,000 per year, and has just been going for a few months. Perhaps your domestic program had too tight a time constraint. But even at a few tens of thousand per year, it is trivial as far as percentage of vehicles is concerned. But, it might be crucial as far as technological development is concerned.

    Fossil fuel are underpriced because they do not include the cost of sequestering their fossil carbon nor the cost of wars in the Middle East to stabilize the supply. The cost of global warming is externalized onto future generations and tax payers pay for the wars. Motorists do not pay those costs. They get a subsidy.

    What is the externalized cost to future generations for PV panels?

    Is the U.S. fighting wars for silicon?

    this is one of the most important programs in Europe...sell 20,000 electric cars for 2010

    Could you give me a name, and maybe a URL? A quick google found the European Commission with a relatively small program, with no targets for EV deployment:

    "Under FP7, calls have been launched in July 2009 and July 2010 to implement the Green Cars Initiative, with an overall budget of around € 200 million. These coordinated calls were implemented by the Commission's Directorates-General for Research and Innovation, Mobility and Transport and Energy, and Information Society and Media. The next coordinated calls are foreseen for July 2011 and the EGCI roadmap is taken into account for the definition of the topics."

    The word "amortize" (for a price) is absolutely economicist

    Yes, it is. You asked for possible reasons why consumers weren't buying EVs. Unfortunately, consumers look at the price tag first.

    As far as sales volumes go - don't forget, the Prius has sold 2M worldwide, and it has a full electric drivetrain, uses only 40% as much fuel as the average US vehicle, and was cost competitive at$3 gas.

    How it comes that a basically fossil fueled society (over 80% is powered by fossils at world level) can underprice its very source of motion?

    Easy - don't price in Climate Change; supply insecurity (if you blame oil supply problems for the recent Great Recession - well, that cost maybe $10T in lost equity valuations, and perhaps $1T per year in lost incomes - both costs are still with us; and a $3T war for oil.
    The movele plan is to put in the streets 250,000 EV's by 2014. There have been so many plans, among others to get 1 million cars by 2020. As I said, they have so far missed the target for 2010 by two orders of magnitude.

    Of course Climate Change effects and pricing will never be interiorized in the fossil fuel costs. Among other things, because trying to put price to Nature is a big mistake. If you internalize the envirnomental costs and try to use fossil fuels and then wipe the house and leave it as originally was before using them, you will never get the EROEIs that gave place to the world you know, enjoy and try to maintain at every cost. That is, the American (or European for the case) way of Life will not exist.

    The only social system that does not need almost any environmental cost internalization is the one of hunter gatherers, with an EROEI of about 5 or so. If you want mobility, bananas from Central America, wine from Australia or shoes from China and going for holidays to Cancun for just one week, that is a society with an EROEI of between 100 and 20. Then, pretending to interiorize the environment costs for this society is simply impossible, not with the fossil fuels, neither (or even less) with the myth of "green" technologies like EV's, which at the end are totally underpinned by this powerful (and of course polluting) fossil fueled society. Fossil fuels pollute, but if energy is the ability to make job, the creation of GDP is, in at least an 80%, the result of having available 10,000 million Toes/year of of fossil fuels. The GDP pollutes and the GDP growth increases pollution.

    El Proyecto MOVELE, gestionado y coordinado por el IDAE, consiste en la introducción en un plazo dos años (2009 y 2010), dentro de entornos urbanos, de 2.000 vehículos eléctricos

    2.000, not 20.000. This is a very small program.

    If you internalize the envirnomental costs and try to use fossil fuels

    Why the heck would you continue to use fossil fuels??? You'd switch to wind, solar, nuclear, wave, etc, etc.

    If you want mobility, bananas from Central America, wine from Australia or shoes from China and going for holidays to Cancun for just one week, that is a society with an EROEI of between 100 and 20.

    Wind has an E-ROI of about 50. Certainly above 20. More than good enough.

    "green" technologies like EV's, which at the end are totally underpinned by this powerful (and of course polluting) fossil fueled society.

    Not at all. Renewables/nuclear can power the manufacture and operation of green tech like EVs.

    20,000 for 2011, not 2,000. The ups and downs of the government in its attempts to promote the electric car have proved wrong. They have changed and accomodated programs for the EV to the reality (if you can not comply with the program, adapt the program to the reality) more frequently than changing their own shirts. 50,000 programmed for 2012 and as I quoted from IDAE, up to 250,000 for 2020.


    But do not worry, they may change again, if reality does not match with the programs. We had once in mind the one million EV cars program, similar to the one of Obama for the US, but being 15 times less economically powerful than the US. Now, they have hiden in the bednight table the 1 million EV's program, but they continue dreaming on developments, going even beyond the left and right limits of the table of elements. Technooptimists have no limits even in the table of elements.

    What they like most is the exponential growth patterns: see? 20,000 in 2011, 50,000 in 2014, 250,000 in 2020, 1 million in few years more and the 900 million circulating around the world by 2050, no more. Exponential growths provoke some kind of orgasm to many technobelievers.

    Interesting the quote of the El Pais newspaper:

    'In 1899, Henry Ford approached Thomas Edison and interrupted a speech on storage batteries to power electric vehicles. Ford showed to Edison the prototype of ICe car he was preparing. Edison listened to him and at the end he said to Ford: Boy, you are in the right path. This car has an advantage over the electric one, because it provides its own energy'

    Wind has an E-ROI of about 50. Certainly above 20. More than good enough.

    Oh, then there is no problem. If science has determined that wind has an EROEI of 50, and we have to believe it, then we can tell the Army to go and fight in the Afghan mountains with wind generators as a power source. Or fly the F-18, or power the merchant vessels full of containers or refrigerated fruit for one month with wind generators or kites. We are already late in preparing a wind powered world which is self breeding. I already see the 150 tons electrically powered cranes lifting the blades, the nacelles and the pole, the bulldozers preparing and pouring the concrete in the foundations or opening roads to the mountains to take the wind generators up. I can imagine the gigantic blast furnaces powered by electricty from wind and trucks or trains coming from mines with the mineral and trucks or trains going to factories to laminate, all of them powered with wind energy, be that directly or through energy vectors like hydrogen. After all, if we have 50 in EROEI of wind energy, we can afford to lose 20 and go to EROEI 30 in the transformation way for the energy vector, isn't it?

    No problem to power the 100 million tractors in the agriculture, with hydrogen as a vector of wind energy. Or the 200 million trucks and buses plus heavy machinery for civil works and mining with elecrticity. No problem, no problem. No need of fossil fuel energy to continue as we are today.

    You have definitely convinced me.

    According to that article, the price of the EV was roughly double the price of a comparable ICE.

    People do respond to prices...

    You know, sarcasm may seem fun, but it's really just annoying.

    If all you want to do is vent anger, go find a therapist.


    Here's a few electric transportation solutions:

    Here are electric UPS trucks. Here is a hybrid bus. Here is an electric bus. An electric dump truck. Electric trucks have much less maintenance.

    Kenworth Truck Company, a division of PACCAR, already offers a T270 Class 6 hybrid-electric truck. Kenworth has introduced a new Kenworth T370 Class 7 diesel-electric hybrid tractor for local haul applications, including beverage, general freight, and grocery distribution. Daimler Trucks and Walmart developed a Class 8 tractor-trailer which reduces fuel consumption about 6%.

    Volvo is moving toward hybrid heavy vehicles, including garbage trucks and buses. Here is the heaviest-duty EV so far. Here's a recent order for hybrid trucks, and here's expanding production of an eight ton electric delivery truck, with many customers. Here are electric local delivery vehicles, and short range heavy trucks. Here are electric UPS trucks, and EREV UPS trucks. Here's a good general article and discussion of heavy-duty electric vehicles.

    Diesel will be around for decades for essential uses, and in a transitional period commercial consumption will out-bid personal transportation consumers for fuel.

    Mining is a common concern. Much mining, especially underground, has been electric for some time - here's a source of electrical mining equipment. Caterpillar manufactures 200-ton and above mining trucks with both drives. Caterpillar will produce mining trucks for every application—uphill, downhill, flat or extreme conditions — with electric as well as mechanical drive. Here's an electric earth moving truck. Here's an electric mobile strip mining machine, the largest tracked vehicle in the world at 13,500 tons.

    Water shipping and aviation can also eliminate oil: see my separate post on that topic.

    Here's a terminal tractor that reduces fuel consumption by 60%.

    Farm tractors can be electric, or hybrid . Here's a light electric tractor . Farm tractors are a fleet application, so they're not subject to the same limitations as cars and other light road vehicles(i.e., the need for small, light batteries and a charging network). Providing swap-in batteries is much easier and more practical: batteries can be trucked to the field in swappable packs, and swapping would be automated, a la Better Place. Zinc-air fuel cells can just be refuelled. Many sources of power are within the weight parameters to power modern farm tractors, including lithium-ion, Zebra batteries, ZAFC's and the latest lead-acid from Firefly Energy, and others.

    It's very likely that an electric combine would be an Extended Range EV: it would have a small onboard generator, like the the Chevy Volt. Such a design would be 50-100% more efficient than a traditional diesel only combine, and would allow extended operation in a weather emergency.

    Most farmers are small and suffering, but most farm acreage is being managed by large organizations, and is much more profitable. Those organizations will just raise their food prices, and out-bid personal transportation (commuters and leisure travel) for fuel, so they'll do just fine. As farm commodities are only a small %of the final price of food, it won't make much difference to food prices. The distribution system, too, will outbid personal transportation for fuel. Given that overall liquid fuel supplies are likely to only decline 20% in the next 20 years, that gives plenty of time for a transition.

    Even hydrogen fuel cells could be used, though they're not likely to be cost-competitive soon with the alternatives. PV roofs certainly could be used to extend battery life, though the cost effectiveness of that will depend on how much of the year the tractor is in the field. Electric drive trains are likely to be much more cost-effective than liquid fuels, but locally produced bio-fuels would certainly work. Also, fuels synthesized from renewable electricity, seawater and atmospheric CO2 would certainly work, though it would be rather more expensive than any of the above.

    Any and all of these is several orders of magnitude cheaper and more powerful than animal-pulled equipment. One sees occasionally the idea that we'll go back to horses or mules - this is entirely unrealistic.

    The easiest transitional solution may be running diesel farm tractors on vegetable oil, with minor modifications. Ultimately, farmers are net energy exporters (whether it's food, oil or ethanol), and will actually do better in an environment of energy scarcity.

    Iron smelting currently uses a lot of coal, which isn't oil, but is a fossil fuel which we'd like to eliminate. Iron used to be made with charcoal, and iron oxide can be reduced with hydrogen from any source. Most of the steel used in the USA is reclaimed from scrap (and when industries mature, essentially all of their steel can be recycled) ; all it takes is an electric furnace to re-melt it, and the electricity can come from anything.

    The US Navy plans to go reduce it's 50,000 vehicle fleet's oil consumption by 50% by 2015. They plan by 2020 to produce at least half of its shore-based energy requirements on its bases from alternative sources ( solar, wind, ocean, or geothermal sources - they're already doing this at China Lake, where on-base systems generate 20 times the load of the base), and it's overall fossil fuel consumption by 50% by 2020 with EVs and biofuel.

    Some question the stability of the electrical grid, in an environment of expensive fuel. Utilities like the idea of "eating their own cooking". Here's an electric utility boom lift. Here's a consortium of utilities considering a bulk purchase of plug-ins (and a good article). Here's an individual utility buying electric cars. Similarly, utilities are buying hybrid bucket trucks and digger derricks. Here's a large commitment by two major utilities .

    Too many good links to look at them all, but a comment about the farm equipment, and the combine in particular. Doing an EREV combine seems like a very expensive solution for something that only gets used a month or two a year.

    Having grown up on the farm, I am always amazed at just how many things can be done with the humble farm tractor - it is possibly the most versatile single piece of powered equipment ever invented. I am, a fan of the EREV concept for a tractor, as they often do short run tasks, where electric only would suffice, and weight is not a real issue. And for the all day jobs, you can't beat a diesel generator for efficiency, so put them together and you have a good solution. So, if the farm has one electrified tractor, then the better way to go for a combine would be a return to the less sexy but very cheap pto combine - I have used these myself, and they are just fine - just not as fast and sexy.

    So, for an electrified farm, "put all your batteries in one vehicle" - the tractor - and then use that for everything.

    And if you follow no-kill farming techniques, you eliminate the plowing - the most energy intensive operation of all, and your tractor can be much smaller. Then for harvest time, mount a diesel gen on the front of the tractor for extra power to run the combine.

    This actually brings up the question of an "electric combine" where the various movements are powered by individual servo motors, instead of the labyrinth of shafts and chains that the current mechanical beasts use.

    an EREV combine seems like a very expensive solution for something that only gets used a month or two a year.

    I have the impression that some combines travel quite a long distance in harvest time from farm to farm and even region to region, for a sweep a somewhat longer than that.

    Some bigtime harvest crews go from April to November steadily moving north from Texas to Alberta.

    Times have changed since my grandfather fielded this crew for his threshing operation.

    Ahh, but it was powered by a biofuel!

    There are indeed harvest contractors who do that, and the same in Australia. My brother sold his combine years ago and decided to just use contractors. Problem is, you can't always get them when YOUR crop is ready, especially if there are weather interruptions.

    For a farmer to own his own machine, a low cost PTO one is the way to go. And if he is your modelk farmer with an electric tractor, then why not?

    I might add, those contractors use the biggest machines available - 300-500hp. That is a LOT of load for a battery system.

    What might become a feasible alternative is to separate (un-combine!) the reaping and threshing functions. Reaping (the actual crop cutting) obviously must be done in the field, but has a relatively low power requirement, and the threshing is what needs the power. It is more work to then bring in the whole plant - straw + head, but then an electrical powered unit can do the threshing, and since you have the straw right there, you could post-process that into bales or pellets.

    Many crops are windrowed, so the two functions are already separated. The windrows could then be collected and brought to a stationary (but portable) threshing unit at the side of the field. this sort of thing is already done for crops like sugarcane, where the processing is centralised, so it's not really that big of a deal.

    I expect that specialised electrical tractors for a farm might look a bit different to the current ones. Many ag tractors are built specifically to be heavy - to increase traction. Many have counterweights at the front, wheel weights on the wheels and tyres filled with water! Not unusual to have a ton or three of extra ballast weight! Three tons of forklift style lead acid batteries would be about 100kWh of useable capacity, and three tons of LiFePO4 would be about 300kWh.

    Would also cost about $120k for that Li battery pack, but then, a new 200hp tractor is $200k anyway, and then you have to fuel it. My brother's fuel bill is about $60k/year, and 3/4 of that goes into the tractor.

    Biofuel powered indeed.

    You might have noted the mule and reins to the driver sitting on the box of a wagon just visible in front of the smokestack. Not only did the boiler run on biofuel but all the men and the draft animals did as well.

    though it may have used a bit less fodder than this operation

    interesting idea un-combining the combine. I've another picture with an even bigger crowd lined up on the other side of the tractor with, I believe, the threshing machine off camera indicated by a long belt strecthed toward it from the big flywheel type PTO on the steam powered tractor.

    I wonder what sort of price diesel will have to reach before switching to mobile electric farm equipment becomes widespread? Well this key post is about energy storage possibilities for the household-almost but not quite full circle back to the biofueled steam tractor.

    Great photos!

    The second one is not too different from a piece of machinery that we operated on my family farm a couple of decades ago. It was a "chaff cutter", that took sheafs of oats - the old style, cut, rolled up and tied by a reaper and binder - cut them into 1/2" long pieces and bagged them for horse feed. The unit looked very similar to that, and was built around the turn of the century, powered by a belt from a stationary steam engine. We powered it from a belt from the tractor - our old 1950's era Fordson had a flat-belt pulley on it - something you NEVER see on a tractor these days!

    Took five of us to operate the thing, and if it wasn't the dustiest job in the world, then it was damn close!

    I think the un-combining will start to happen. My brother in Australia wanted to buy a pto combine to have at the farm, to be a cheap way to harvest if he couldn't get a contractor. This happened to him last year - cost $40k in weather damaged crops as the contractors were all busy, and he was sitting there with his two tractors and tip truck doing nothing! A pto combine is slower, but it can still do the job.

    But the return of the threshing machine poses some interesting possibilities;
    - It can operate 24hr, so can be half the capacity of the combine
    - it can be under a shelter, so can operate in the rain, and be cooler than the combine in the field
    - because it is staitonary, it can be designed more "open" to allow better cooling of moving parts.
    - the moving parts, and the frames that hold them, do not need to be built as robust, as they do not operate while driving over bumpy fields. For the same reason they are likely to have a longer life
    - the threshing system can have lower losses. most combine lose 1-2% of the grain - trying to get this last means going real slowly, and letting it go means you have volunteer seeds coming up the next year. The stationary unit can have more screening to get this last bit, and even it if doesn;t, it is not back in the field
    -the ability to then bale/pelletise the straw creates another easy income opportunity. An electric pellet mill can be attached to the end of the thresher for continuous production. IF you get one ton of straw per two tons of grain, and with pellets selling for about $200/ton (compared to wheat at $300) then you have a 33% increase in cash return per acre - not bad!
    -The windrower can easily be powered by a low power electric (or diesel tractor), as can the tractor/truck that brings the crop to the thresher. If the thresher can be located at the edge of the field, then the transport distance is minimal. In fact, it is not much different to what the tractor and grouper bin does today
    - it would be possible to have the a second battery pack at the thresher, rapid charging, while the first one is operating in the tractor. since the tractor is coming back to the thesher all the time, the driver does the changeover when he is ready for a drink break (coffee in the US, beer in Australia) which would be about every hour. The two minute changeover would have a minimal effect on productivity.

    When the harvest was happening last year, there was a 400hp combine operating, plus the 200hp tractor with the grouper bin. They would have been using about 120L diesel/hr (32 gal). With diesel prices at $1.30/L in Australia, that was $156/hr. The equivalent electricity would be $40/hr, and you don;t have the maintenance and depreciation of two expensive diesel engines, operating under the worst (hottest and dustiest) conditions.

    A really out there possibility, for irrigated areas, would be to have the mobile combine (doing the threshing) powered by electricity from the centre pivot irrigator! The cable can move in or out along the irrigator, and the combine would travel parallel to the slow turning irrigator - i,.e. it is going in and out radially. There would be some inefficiency by overlap towards the middle from doing this, but that would be an acceptable tradeoff for going electric. The irrigator could also have a "receiving tub" at the inner end, which the combine can discharge into while moving, and this then discharges into the waiting truck - eliminating the grouper entirely.

    The combine could also just drag the power cable behind it, over the ground, in rock and stump free fields, like a "water-winch" style travelling irrigator does with its hose. There are suitably armoured cables available for the mining industry. The combine would have to go up and back, rather than round and round, but that's entirely doable.

    if the farm is in a windy and/or sunny area, a good portion of the power could be provided by on farm generation too, though this is not necessary. That said, I think production of renewable energy is a bright opportunity for farms to make extra income over what they do today.

    There are lots of possibilities, it is just that no one in the farming, or ag equipment business, is looking at them - they are too invested in what they are doing today. There is a huge opportunity out there.

    {edit to add} A quick search shows that there are plenty of (smaller) stationary threshers available, mostly in India and China! but there are some being made here, like this one by Almaco, which is available with a 8hp gs engine or 5hp electric.

    Doesn;t say what the throughput is, though at that power it would be small.
    For a larger application, I guess the simplest thing to do would be to park a pto combine, or find a mobile one that has a dead/dying engine and just re-power with electric. When the thing doesn't have to move itself+ tons of grain over soft fields, there is a substantial reduction in power!

    Turns out there are a few companies that make stationary threshers, mostly for the certified seed growers.

    Interesting article here, from 1999, about small scale grain growing, and the Euro and Japanese machinery used to do it. This stuff would be easy to electrify as it is 10's of hp instead of 100's;

    The same place has a complete, and up to date listing of all sorts of Euro/Japanese equipment, including small reapers, threshers and combines, any of which could easily be electrified, and some refurbished pto combines.

    And, they have a battery-electric (walk behind) harvester - for salad greens, like spinach, where you don;t want exhaust fumes on them;

    So, electric can be done, today, at small scale - which is the appropriate place to start.

    Like the rest of farming equipment has, it can then progress to ever larger stuff.

    Nick - when do we get started?!

    You've got lots of really good thoughts there.

    Like the rest of farming equipment has, it can then progress to ever larger stuff.

    EVs certainly scale, like the electric mobile strip mining machine, the largest tracked vehicle in the world at 13,500 tons.

    when do we get started?!

    I would guess it'll happen when it becomes absolutely clear to Caterpillar and Deere's customers that current diesel price levels are permanent.

    Actually, I don't think Cat and JD will lead this charge. It will take some independents, or euro/chinese/korean mfrs to do it first, because their markets will be more likely to take it up. I think the US will be the last place to adopt electrified farming.

    And if it is started somewhere else, then that will make US farmers, and equipment makers, even more reluctant, as that would be admitting that "they were right" - you see this all the time in other mfr industries, plumbing, electric (why are we still on 120V?) and so on.

    There will be a bunch of EV conversions, just like with cars, and the JD's will, just like the carmakers, only do it when they are given scads of gov money to do what the backyard guys have already done.

    Just look at their refusal to do any work on co-fuelling their tractors with the one fuel their customers can make themselves - ethanol! Minimal modification required, can be adapted to existing machinery, and none of them want to touch it! I can't see them jumping into electric - this will be a disruptive shift, IMO.

    I would start with a maker of electric forklifts - many forklift co's make "off road" forklifts, though not electric - there would be a place to start.

    The leader in electric forklifts is a company called ... Toyota!

    Yeah, the manufacturers will resist.

    But look at the way I phrased it: this will happen when the customers realize it's necessary.

    Fleet buyers are very conservative: they're making big commitments in capital equipment; there are huge implications for operations and maintenance; and they're cogs in very big organizations, with huge amounts of disempowering hierarchy and after-the-fact accountability (scapegoating).

    Fleet buyers want uniformity, standardization, predictability and low capex and opex. They want low risk.

    So, fleets are the high-value target for EVs, but they're tough prey.

    You raise interesting points about stationary machinery. I have seen many people complain that current farming methods cannot be done using electricity and so electricity is useless for farming. The same for other industries. By changing the method of production from one suited to liquid fuel to one suited to being connected, by moving equipment from the moving to stationary system, that changes to usability of electricity. How many other things can be readily adapted by changing the model as to how they are used?


    Moving from trucks to trains is a clear example.

    Going from commuting in cars and flying in planes to telecommuting and high-resolution-video teleconferencing are pretty good ones.

    Gotta be creative, and think outside the box...

    There are probably lots of things

    if you were on a "farmable" desert island, and had abundant hydro electricity, and no diesel, I think you would come up with a way to electrify everything!

    The harvester is the best example of a mobile "processor" that can be made stationary and electrified.

    Other mobile jobs, like plowing, can be tackled by - not plowing! These guys in Australia doing no kill cropping, just seed directly into the pasture, no plowing OR spraying involved. By seeding into dry ground with a disc seeder, the power requirements are minimised (as is soil compaction) and they can do it with an electric pick up truck.

    This beast has a 150kW(200hp) electric motor and batteries for 50mi of hwy driving - the farmer in question lives 12mi from town, so no problem there.

    It is not that electrifying can't be done, it just needs some different thinking. IT can't compete with diesel for high power, all day long broadacre plowing//harvesting, so don't ! It is clearly better at smaller scales, though I can see larger scale stuff happening when fuel is expensive enough.
    And, once you do the work to "electrify" the farm, like running power lines to fields, it all becomes much easier...

    Would be interesting to do a comparison of an electric farm, and one that grows its own biodiesel. I think there might be some material for a future key post there, for someone who likes to "do the math"....

    It is not that electrifying can't be done, it just needs some different thinking.

    Yes, that is exactly the key. I think that if electricity had boomed while oil and coal lingered then the industrial age would have taken a different path.


    Some things would have changed. Obviously, aviation and highway travel would be rather smaller without oil, and rail would be much larger. OTOH, oil really wasn't needed for industrial civilization: consider that industrial civilization was well developed before the period of roughly 1915-1950 when oil took off.

    Electric vehicles came before ICE's, and were very successful before dirt cheap gasoline appeared. The Model T was designed to run on ethanol, and used soy fibers instead of plastic.

    Oil replaced coal for the English Navy in WWI because oil-fired ships could travel 20% faster. That 20% margin for top speed is enormous in time of war (it was the crucial difference in naval battles with coal-fired Germany), but how much difference does it really make for commercial freight?

    For the Navy ships it also made refuelling faster, and the oil could be stored in parts of the ship that coal could not. so more speed, more range and less refuelling time made for a great advantage. That said, the only major engagement between them, at Jutland, ended indecisively and was really nothing to do with the ships speeds - it was more that neither admiral wanted to lose any ships.

    For modern freighters, they could work with coal, but the same issues - refuelling time and hull space/volume - remain. If bunker fuel is expensive enough, or if the ship is carrying coal already, then it would make sense. Presently, I doubt it really does for shipping, especially since very few ports handle coal.

    I think the biggest thing is the "independence" that ICE vehicles gave individuals - very empowering.
    But now, that owning an ICE is very expensive, and you have to work at least one day a week just to pay for it, and then in your spare time you try to avoid driving it, they have become a chain around the neck for many people.

    A city with a good transit system, where many people have the choice to not own a car, is great place. A city where you HAVE to own a car - EV or otherwise - is not so good...

    For modern freighters, they could work with coal... I doubt it really [makes sense] for shipping, especially since very few ports handle coal.

    I agree. I'm simply making the point that oil wasn't essential to the development of trade. I would argue that batteries would work just as well as coal...

    I think the biggest thing is the "independence" that ICE vehicles gave individuals - very empowering.

    Yes. This is enormous, and can't be denied.

    now, that owning an ICE is very expensive

    That's simply a modern choice. If people kept their cars for 30 years, they'd be much less expensive. My last purchase was a 7 year old car, and it replaced a 20 year old car that had been crushed by a falling tree! Unnecessary (fashion-driven) depreciation is by far the largest expense for new car buyers.

    An EV, kept for 30+ years, would be far less expensive than your average new ICE vehicle.

    A city with a good transit system, where many people have the choice to not own a car, is great place.

    I agree. Good transit is a great thing, but it's mostly useful for commuting. Point-to-point travel requires personal transportation.

    Personally, I like and use car-sharing, like The best of all worlds.

    To notanoilman:

    I think that if electricity had boomed while oil and coal lingered then the industrial age would have taken a different path.

    Not much chance of that ever having happened. We already controlled fire so fossil fuels just fell right into the mix. As Tom said in the key post with high energy density (easily released), storable for millions of years, nature's battery is awful hard to beat. It is just that the recharge cycle is a bit long for us to ever count on such a windfall again. Which emphasizes Paul's point even more
    It is not that electrifying can't be done, it just needs some different thinking

    To Paul:

    Though it is very hard to see in the second photo I posted (I shrunk it to about 480width,310height to conserve bandwidth), that steam engine is on the same tractor as in the first photo. There is a man sitting on the front wheel just to my grandfathers right. The tractor looks very similar to some Case models I came across, but as stationary steam plants preceded the self propelled variety they likely looked very similar with the wheels off. I've been wanting to post those pics for a while but never had the time when the proper subject was in play. Now they are out in the public domain. Century old photos did seem to spark the discussion nicely. Are you more farmer or engineer at heart
    ?- )

    [edit add in]
    A few months back TOD regular from down under, scrubpuller, posted a link to a centrally pivoted electric till/harvest system that he had developed. He had a couple comments in the 'Flywheel' post threads on the current TOD page and might still be monitoring that one--it would take me quite a while to find the links, they included pictures of it in operation.

    I think you missed my point. What if fossil fuels didn't just fall right into the mix. What if they had not been found in sufficient quantity? What if developing them had been much harder? What if mining and drilling technology had hit obstacles? What path would industrialisation have taken place if the production rates of these fuels had never reached the peaks they did?


    There is an extremely high probability we wouldn't be typing to each other over the internet this century without millions of years of stored solar energy having been extracted by our economies in the last couple/few centuries. Remember coal and steel are joined at the hip, remove coal and you remove the availability of steel, remove iron and steel won't be there to extract and ship coal. Wood/arable land based economies have left a long trails of up and downs in the dust.

    Any point after the fossil fuel use/population explosion had travelled together for a while a sudden weaning from fossil fuels would have greatly curtailed time available to the population as a whole that was not dedicated purely to obtaining subsistence. That of course would limit the amount of human ingenuity that came to light and on and on. Optimists are hoping we maybe have moved far enough along technologically to have dodged that bullet at this point, doomers say there is no way in hell it can be dodged.

    I'm guessing some modelers might give all kinds of potential outcomes if fossil fuel access or even total availability peaked in or even hit a wall in 1800, 1850, 1900, 1950 or whatever. Their assessments would be little better than sci-fi though--that said those aren't particular bad settings to work a story from--decent novels have been made from less.

    But that still assumes that industry would have developed along the same lines and hit the same wall as the fuels. If more electricity and less fossil fuels been available would manufacturing have gone down the same road or would it have evolved differently. What alternative choices would have been made? Would a discontinuous process have been made more efficient while continuous processes abandoned? It is not just looking back to make a good story but, by looking at the past, looking to the future. What would have happened if we had never become so dependent on FF and can that lesson be applied to the future?


    apparently you missed my first sentence--there is a very high probability we would not be typing to each other over the internet this century--things moved pretty slowly before fossil fuel was added to the mix.

    But if copper wire grew from trees much like the spaghetti in this fine BBC April 1, 1957 production, it truly is hard to say just what path we might have taken with easily harnessable electricty
    ?- )

    Strange that Kurtz doesnt consider the massive energy storage that is used in most electric grids; hydro and pumped hydro, anything from a few GWh to >1000GWh storage.

    I suppose he did not intend to explain all the possible energy storage systems, being the harvesting of grain, or dried vegetables, or straw, to be used for human and animal food in an agricultural society, one of the bests, for instance.

    One of the things we are discussing now is the selling point of the car manufacuring industry, claiming that electric cars could be used as a buffer to store intermitent energies, when massively deployed and when the intelligent networks are working well. This is a silly argument, because if batteries are today the weakest link in the chain of the electric car, because the costs and limited life cycles, if we most likely duplicate the charge/discharge cycles for loading the car and offloading the batteries for the grid benefit/needs and for the car motion itself, then we are shortening or halving the battery life. And who on Earth of the electric car apologists or energy storage prophets has thought in this burden?

    We are currently pumping up in Spain with about 4 GW installed power (for 100 GW total generation installed power) and intend to grow to about 7 to 10 GW. So, I know very well this possibility, which losses about 30% in the process.

    We have currently peaks of wind generation covering over 50% of the national electricity demand and solar PV peaks covering 6% of the demand, and therefore, as you can imagine, we have studied and are studying very carefully these solutions, and costs and possibilities.

    But nobody would think that there is a free lunch, even for the pump up. Recirculating water is bad for the oxigenation of the fresh water flows and life in them. Europe, for instance, has over 80% of the big river basins already occupied/flodded by dams for hydroelectricty or irrigation. A little bit of top down analysis is always convenient.

    if batteries are today the weakest link in the chain of the electric car, because the costs and limited life cycles, if we most likely duplicate the charge/discharge cycles for loading the car and offloading the batteries for the grid benefit/needs and for the car motion itself, then we are shortening or halving the battery life.

    The most important use of vehicle batteries in the grid is for Demand Side Management (DSM, aka Demand Response). The battery charging is scheduled based on the needs of the utilities, within the constraints set by the consumer. This places no, repeat, no additional demands on the battery.

    V2G is different - it will be very useful someday, but DSM will be the important thing for a while.

    Imagine I set my own constraints by the so called Demand Side Management to the moment the price of electricity is low (valley) and, in effect, there is no additional demand to the batteries (no more charge/discharge cycles than expected in the life cycle). But then in the morning, when electricity price is high, the pregnant wife starts with periodical contgractions, while your battery is discharged, awaiting for the intelligent network to offer low prices. The minimum charging time is half an hour (in the best case) at 80 percent. This is one of the examples posed in an electric car conference in Madrid. The battery car does not suffer. Humans do not matter. The versatility density and suitability of oil is not so easily replaceable.

    The example I put in the previous mail was obviously for V2G or massive storage in car batteries. What you mention as DSM is only an attempt to smooth present transitions between valleys and peaks. That is another issue.

    then in the morning, when electricity price is high, the pregnant wife starts with periodical contgractions

    1) If you have a pregnant wife, you're not likely to set your EV charging profile in such a way that you won't have enough power to reach the hospital, are you???

    2) The hospital is only a few miles away for most people, and EVs will have greater range than present EVs: getting to the hospital would use 10% of the capacity of the EV, leaving up to 90% reserve for charging flexibility.

    3) Only a small percentage of the population has such constraints.

    4) This is what extended range EVs like the Volt are designed for. Use electricity most of the time, use fuel 1%-20% of the time, depending on your preferences and needs. Single vehicle households may stay with EREVs forever, and leave the EVs for the multiple vehicle households (which is most US households, by the way).

    This is a non-problem.

    The versatility density and suitability of oil is not so easily replaceable.

    If everyone in the US had an EREV like the Volt, liquid fuel demand for personal transportation would shrink from 140B gallons per year to about 15B - an amount which could be supplied by ethanol. For that matter, we could use synthetic fuel (from electrolized sea water and atmospheric carbon) - it might cost $10/gallon, but it wouldn't matter because we'd use so little.

    The example I put in the previous mail was obviously for V2G or massive storage in car batteries.

    Sure, and I disagree with you on the usefulness of DSM for handling seasonal disruptions: it would be an essential part of dealing with them. Remember, any rational grid planner will have a wide, diverse array of power sources, and the loss of one will not eliminate all power. So, the ability to easily reduce consumption by 20-40% without general disruption will be very, very useful.

    On the other hand, V2G will be useful someday: li-ion batteries have much longer useful lives than lead-acid: some designs allow up to 10,000 relatively deep discharge cycles, a number which is very unlikely to be exceeded in a vehicle's lifetime.

    Some of us are not gullible enough to believe manufacturers' longevity claims for products that have been in existence for only a few years.

    I want a PHEV battery that can be deep cycled 2 times per month, recharged over a 15 day period by photovoltaic panels, last for 30 years and cost about the same as a steel gasoline tank. Tall order?

    manufacturers' longevity claims

    Life cycle testing is easy, and reliable. Chronological life testing is harder, but there are accepted methods for accelerated life testing. You can be sure GM pursued these methods very, very thoroughly before giving a strong warranty for their battery pack.

    Tall order?

    The perfect is the enemy of the good.

    If one can not reduce the cost of an automobile by driving it less (because the battery degrades as the car sits unused), then EV's and PHEV's will be unaffordable for a lot of people who currently own cars.

    With the lead acid batteries in my PV system, there were decades of experience and books available to teach me how to care for the batteries. They made me confident enough to purchase the batteries. I wonder what the used market will look like for EV's.

    because the battery degrades as the car sits unused

    I think that the newest li-ion batteries are very stable, time wise. The Volt's batteries have an 8 year warranty - the battery should have at least 70-80% capacity left at that point.

    EVs and PHEVs will last a very long time, which will reduce annual depreciation costs. There will be plenty of used cars, eventually. That time lag is the kicker, of course. People who can't buy a new vehicle will just have to buy an older high-MPG vehicle, like a Civic.

    A Prius costs well below the average for new vehicles: depreciation is by far the biggest cost for the average driver.

    1) If you have a pregnant wife, you're not likely to set your EV charging profile in such a way that you won't have enough power to reach the hospital, are you???

    If I had a pregnant wife, which is not the case, these days with the state of the art in the automotive industry, I most likely will have an ICE car with more than half deposit ready, rather than an electric car that has received an unknown battery replacement in an electric refueling station (case study 1, for recharging vehicles). I can predict somehow my charges/discharges patterns in an EV, but I cannot predict if the contractions arrive when the car is less than half, or when I have just arrived from work with 10% charge and had just plugged it in. This is real life, not theoretical life.

    2) The hospital is only a few miles away for most people, and EVs will have greater range than present EVs: getting to the hospital would use 10% of the capacity of the EV, leaving up to 90% reserve for charging flexibility.

    It is clear that you are thinking in the US. I live in Europe, where the Social Security is excellent, but when thinking in EV’s, I am thinking in the world, with about 900 million private cars moving around, with huge infrastructures already created for ICE’s but not for EV’s; with petrol stations that will probably have to triple in numbers for the electric refueling stations, if equivalent functions are needed with the EV. I am thinking in many countries I have visited, where even the petrol stations have to be chosen carefully, because if you miss one, you run out of gas for sure, as they are sometimes every 400 Km. I am thinking in many of the 200 countries of the world, where hospitals are not so close, where having electricity for illumination (not only a private garage with a >16 Amp at 220 VAC breaker) is a luxury. I am thinking in a country, like Spain, where 70% of the 30 million private cars in a 46 million population sleep in the streets, not in private garages and the laying of infrastructure (trenches, ducts, thick –very thick- copper cables for supply in the streets to the charging points) implies a new city. I am thinking, for instance, in the ICE vans crossing the Sahara desert from Tripoli to Niger, with just the deposit and a couple of extra petrol cans in the cage. I cannot imagine replacement or density enough in the existing batteries. Nor for the Humvees patrolling Iraq.

    3) Only a small percentage of the population has such constraints.

    Very much the contrary. Only a small percentage of the world population has NOT such constraints. When Toyota thinks, for instance, about Middle East or Central Europe or Russia or China (important markets for them, for instance), they are thinking in extra radiators of bigger air filters, antifreezing devices or fluids, or ruggedized cars or shock absorbers for impossible roads. They have no even a road map for EV’s in most of the world. They are playing games in US and in Europe, just to keep in the marketing forefront and specially, to get the subsidies from the wishful thinking greenish governments. If EV’s are going to be attractive for Europe and the US only and with some many conditions or buts, they will never see life at global level.

    4) This is what extended range EVs like the Volt are designed for. Use electricity most of the time, use fuel 1%-20% of the time, depending on your preferences and needs. Single vehicle households may stay with EREVs forever, and leave the EVs for the multiple vehicle households (which is most US households, by the way).
    This is a non-problem.

    I agree that you have an extra problem with the ICE’s efficiencies in the US. In Europe, it is usual to have consumptions of 4 litres/100 Km (70 miles per gallon) and ranges of 700 to 1,000 Km in ICEs (430 to 620 miles).
    I repeat, if you solve only the problem (your problem) in the US in this interconnected and globalized world, where the big multinationals have the world as a market, while your market is declining and others are emerging, you will not get the EV’s or hybrids finally taking off or completely replacing the ICEs, before the oil is quite depleted and then, our discussion will have not interest.

    Pedro, you're coming up with some really extreme scenarios. There will be times and places where an ICE is more appropriate than an EV. Crossing the Sahara, living with nomads in Mongolia, visiting the bushmen in the Kalahari, maybe those aren't the best examples of where to introduce EVs. The third world is not known for being the bleeding edge of technology, and has relatively few car sales anyway. Besides, if you're in those places with a pregnant wife, you've got more problems than what kind of car you're driving, as their hospital system is not the greatest. Here in the states, if you can't drive your wife to the hospital (and believe it or not, many people don't even have cars here, yet they don't fall down dead somehow), there are ambulances available.

    ICE will be with us for a long time - long haul trucks, construction workers, those in rural areas. But maybe we can replace gasoline and diesel with cleaner natural gas. There is no one solution for the future. Having more options, including EVs, hybrids, plug-in hybrids, and natural gas vehicles will allow gasoline and diesel to still be available where it is needed most.

    BTW, the plug-in Volt isn't really an extended-range EV, since they changed their story at the last minute, and it is powered directly by a gas engine when the batteries are low or don't have enough power to meet the driver's needs at the moment. It's a standard PHEV, like the upcoming plug-in Prius.

    the plug-in Volt isn't really an extended-range EV, since they changed their story at the last minute, and it is powered directly by a gas engine when the batteries are low or don't have enough power to meet the driver's needs at the moment.

    Well, the Volt doesn't use the ICE at all until the batteries are low (unless you put it in mountain mode).

    Yes, when the battery is low, and when speed is high, the ICE connects mechanically to the wheels. But, that's a far cry from the Prius plug-in, which has only 1/3 the electric range, and uses the ICE immediately for both acceleration and all highway driving.

    I cannot predict if the contractions arrive when the car is less than half, or when I have just arrived from work with 10% charge and had just plugged it in. This is real life, not theoretical life.

    Yes, and I'm baffled as to how this is different from an ICE vehicle. If you're wife is pregnant, you don't let the gas tank get low. Same thing with your EV.

    You really need to start thinking about hybrids and EREVs, and not just EVs. Most people will use them for quite a while, over EVs.

    You also need to wrap your head around the external costs of fossil fuels and oil.

    What about the scenario where the ICE vehicle doesnt start because the interior light were left on overnight draining the battery. Is this an argument to go back to crank starting rather than unreliable electric start?
    I am sure some electric vehicles will become stranded with flat batteries just as ICE vehicles do when they run out of gasoline. I have had this happen to me on several occasions and many more almost running out of gasoline. I have also had my mobile phone running out of charge but dont consider this an argument to replace mobile phone batteries with a small ICE engine.

    Primarily, the battery systems for RE-systems and for EV's will generally get implemented with one or many controls to prevent over-discharge. Even many very simple charge controllers in the $50 range include an LVD Low-Voltage Disconnect circuit to disengage the battery when it hits its chosen 'safe-minimum' level, and this would generally still leave enough power in the battery to operate the car 'in the red', assuming it allows you to override the cutoff voltage.

    But I'm also sure that EV's will run out of power, as you say. I probably wouldn't be averse to having one of those little 1kw putt-putt gennies in the trunk as an emergency backstop, as long as there is a 120v charging option avail for the vehicle. (And I don't think I'd get and EV that didn't have that option..)

    And finally, I think EV's generally have a separate 12v system for the cars electrical system, apart from the traction batteries.

    EVs can certainly run out of power, but I think Neil was pointing out that all cars are fallible.
    EVs and HEVs tightly control the depth of discharge - and recharge for that matter - the regular Prius only cycles between 80% and 40% of full charge (most of the time it sits at about 65%) in order to maximize the life of the battery pack.

    I know the Prius has a 12V battery for the various extras, but it isn't used to start the car, so it is a little smaller than most automotive 12V batteries.

    We're agreed on the hopelessness of hydro pumped storage for individuals, but keep in mind that what's true for individuals isn't always true when you scale up. For individuals, the figure of merit is "can this storage system fit in my garage?". But if you want to store energy for a continent, the question -- as we learned in Nation Sized Battery -- is "Are there enough raw materials on Earth to build it?" And the great thing about pumped hydro is that nature has provided us with a hell of a lot of very cheap water, and some very large containers to store it in.

    Absolutely - indeed, it is arguably the best nation scale energy storage approach for those nations with good hydro storage potential.

    Another practical means of efficient energy storage (chlorine generation for disinfection) == energy storage plus clean water combined

    A different way to think about storing energy is to consider the many ways that energy is currently being used and to vary the amount of usage in such a way so as to generate a product that is required but on an intermittent basis (e.g. when power is cheap). A good example of this is the chlor-alkali process which is used to produce chlorine for chlorinated products such as PVC plastics, chlorinated organic chemicals and chlorine for water disinfection. Chlorine for water disinfection is a significant application on its own. There are "On-Site Generation" (OSG) systems for chlorine for disinfection, e.g. "hypochlorite generators".

    Here is where the energy storage issue comes in. Chlorine generation is a very energy intensive process. It requires about 3 kWhr per pound (6.6 kWhr per kg) of chlorine. Chlorine is usually added to all drinking water (including water in toilets). Water usage is profligate in the US. For example, the 6 million people in the Chicago area currently use about 1 billion gallons of water per day (about 4,000 kg Clorine per day or about 25 mWhr per day, at least). Since chlorine has a lifetime in water of about 6 months (at least a month), the energy content of the chlorination process is effectively STORED in the water. Storing water (with energy intensive chlorine in it) and then USING it later is a very efficient process (>95%). The USE of the energy to create chlorinated water can be effectively metered to produce the chlorine WHENEVER it is best. For example, electricity is much cheaper (and more available) in the middle of the night. It can be arranged to run the chlorine process at a higher current and time it to produce chlorine in the middle of the night.

    An even more exciting possibility is the use of renewable energy (e.g. wind, solar) to produce chlorine (or any other electrically driven production process) when the wind blows or when sun shines and then to STORE it for when it is needed.

    Although this is not likely to be a family by family or house by house possibility for high efficiency energy storage, it DOES offer SOME hope that energy can be effectively stored for real world, high priority applications.

    Not enough to allow BAU to continue, but HOPEFULLY enough to prevent die off.


    Here's an excellent article on energy usage for chemical manufacture, with a great section on chlorine:

    Some key facts relevant to your proposal:

    * Water treatment accounts for only about 6% of chlorine usage. It's mostly used to make PVC plastic and a few other chemicals.
    * U.S. chlorine manufacture requires about 200 petajoules of electricity per year: for comparison, US total usage is about 14,000 PJ/year. So changing the way we make chlorine can only affect our overall electricity picture by 1% or so.
    * Chloralkali plants, like most big electricity-using industries, *already* turn their plants on and off in response to changing electricity prices.

    So in short: your idea is already being used, and it doesn't make much of a difference to our national energy story.

    Probably the most interesting article for a while on TOD.

    Here's my experiences/views.

    Lead/Acid batteries.

    Something I am looking into as I will be moving into a new house this week is a small scale solar/lead-acid battery set up probably with 12V to start with. Maybe power a few LED lights and USB chargeable devices to start with.


    I worked on piece of mining equipment (diesel-electric) that used a flywheel to even out the load on the diesel (1800hp) motor over a digging cycle of 30-60 seconds. The flywheel could store about 10-30kWh and was 8 feet in diameter and turned at 1200 rpm max. It was a bit of a pain to deal with and as far as I know it is the only set up in existence. Also a bit unnerving having 7 tons of rotating flywheel close by. Friction losses not an issue over 1 minute and it took about 45 minutes to spin down by friction losses on its own when things went wrong so you could not use to store energy for a day. No fancy vacuum or magnetic bearings just white metal and behind a metal grill.

    Pumped storage

    A landowner friend asked me to come up with an idea to run wind pump - pumped storage for his rural 160 acre block in Queensland, Australia. It had a 70 metre (200 foot) hill very near. he already had the lower pond in the form of an irrigation pond there and would have needed a tank capable of holding 50 to 100 tons of water on the hill to give him 2 day supply and five wind pumps to pump it up there not to mention the cost of the hydro generator. I feel that pumped storage is best left for the large scale operations.

    Overall I like the idea of iron-nickel batteries or a diesel/biofuel generator best. I think all the links about batteries given in the comments will be very useful for my upcoming project.

    I'm new here, so forgive me if this is a stupid question.

    Is thermal mass also a part of the energy storage solution?

    I'm of the opinion that if we go back to real homes rather than frames designed to keep the aircon/heat inside, we're able to cut demand by half. The problem, obviously, is that that makes your home more costly.

    FWIW, the lowest energy use I ever experienced was when living in an apartment building, originally constructed in the 1940s and remodeled. It stayed cool or warm naturally much longer than I ever thought possible.

    I hope to build a home designed to take advantage of this in 10 years or so, but for now, I have to stay in my framed air box.

    Hi Noble Serf;

    Personally, I sure do think that Thermal Storage is a key form of stored energy, as is stored Coolth in the form of Oversized and Overinsulated Refrigerators and Freezers, and possibly the storage of extra compressed refrigerant, if that is a viable way to hold spare power for later. (I don't know the variables/equipment well enough to be able to judge..)

    But properly built structures is a terrific opportunity.

    I'm also playing with designing some kind of Solar Oven built right into a regular kitchen, which would allow it to double as a heat source for the house when there's nothing being cooked. In fact, it would double as this heat source even when you ARE cooking with it.. and as such it would probably be necessary to have the option to vent this heat right back outside during the warm part of the year..

    I also live in the Northeast, and it's just silly to be spending money for power to keep my fridge at 40f when the temperature right outside the wall is a good bit below that for Much of the year. Not only could you use the ambient cold WHEN it's cold, but it's not at all hard to envision some simple ways to store a bunch of that free Coolth through those warmer days inbetween, during spring and fall.

    (I have a whole ocean of Brine just down the hill from me, and could probably get away with snatching a couple hundred gallons of that for an insulated tank- which would handle pretty much all the Coolth I'd want.. Plus, we have people giving away their Oil Tanks when they switch over to Gas.. if I could figure out a good way to coat such a tank against the corrosion of the Saltwater, which I have to think wouldn't be all that hard.)


    I'm very interested in the storage of heat/coolth too. In fact, the house I currently live in in Alabama has an interesting "feature". It was built in the mid 1950's and the walls/ceilings had poor insulation. However they didn't use just lath/plaster. Over the expanded metal lath there is about 1 inch of concrete and then about 1/8" of plaster. This gives an amazing amount of thermal mass inside that holds the heat/coolth that we pull into the house with the whole-house fan. In the winter,, heat up the house with daytime heat using the fan and close it up at night. The reverse in the summer. BTW, the wood the house is built with is larger and amazingly tough, it's hard to drive nails into the studs and sometimes impossible to extract a nail without amazing effort.

    I'd be interested if anyone has links to methods of building heating/cooling efficient houses that don't just use super insulation and then have to use an active and power consuming ventilation/heat exchange system to make up for being super-airtight. Something lower-tech than high-tech methods.

    I also live in AL. NORBAM as I call it.

    Without learning to live without AC, we do have some challenges.

    The all in one commercial solution I read most about is Enertia Homes. I do not know if their claims pan out this far south, but I do like the ideas they use: ( Lately I have also started to look at a concrete form home for the future.

    Of course we still need to capture and store solar/wind energy if we want to keep our lifestyle similar to how it is now, but I think we (all of us) could easily conserve anywhere from 30-70% of the FF we use now if we just make minor changes. I also think that's the first step.

    Now off to read more about the magic of batteries :-)

    Noble Serf and Aug: You're on the right track. Our house with slab floors, passive solar, radiant heat, and a 450 gallon insulated plastic water tank costs little to heat. Water is heated with home built solar collectors and a heating coil in an efficient woodstove. Heat is stored in the thermal mass of the house and the water tank. Managing the thermal inertia of this system has become second nature for us. The house also stays quite cool in summer due to passive cooling. We're in North Carolina, similar climate to N.Alabama. Natural lighting, integrated thermal storage, solar/wood hot water (a simple copper coil in the water tank), solar pumped/gravity potable water, and careful design all combine to limit our external energy costs to a bit of propane (cooking and clothes dryer) and diesel for equalizing the batteries (very modest use). We use only deadfall for firewood. Earth berming to the north also aids the natural heating/cooling of the structure. We have enough PV production to run a small window AC unit in the bedroom when things get really hot, but use it sparingly. Cooling the house at night with fans normally keeps the house quite comfortable. Oh yeah,,, we had to get used to silly chores like opening/closing windows or thermal blinds.

    Sounds great!

    Design is so important. It doesn't cost much to design properly, and it makes so much difference...

    We're in North Carolina, similar climate to N.Alabama.

    I would doubt that. You said you are at 2500 feet, and also further north. I'd bet the combo is good for at least 10F cooler. Also the dew points are less. Taking in very damp air for cooling can be a problem, with condensation and possibly mold, and just generally being too humid. Thats one thing AC does for you, takes out quite a lot of the humidity. In much dryer N California, my outside AC unit, generates a stream of water when it runs.

    Yeah, I tend to be nonplussed with the "Ultratight" approach to home heating. I think that's based on a model of using the Air Plenum as the Thermal Mass, and not building materials.. I am eager to hear about designs that allow for more natural breathing, where the solid and possibly liquid masses within are the real Thermal Flywheels of the system.

    I wouldn't mind getting 'really pretty tight', and having some form of Heat Recovery Venting.. but I'm truly unconvinced that going to the extreme of tightness is really the answer..

    My place isn't ultra tight but it has begun to approach it as small additions were built much tighter and eventually nearly enveloped the original structure (eliminated over half of the old bearing walls). The building better than doubled in size while fuel consumption-with the exact same Monitor heater-actually dropped about 20%. The stack effect can really show up on a three story at forty below. I haven't put the HRV in yet but do duct it as I go.

    The CCHRC did some research on a common insulation upgrade in these parts-adding stryo to the outside of the home-and found it took something like 6 inches of it to avoid getting the unwanted double vapor barrier mold inducing effect.

    That's a great link, thanks.

    I'm eager to find more info on Insulation Retrofits, and have been looking at the exterior foam option myself, tho' I'm aware of the moisture concern. My initial response is to seek out ways to have the walls be able to breathe, ideally as an intrinsic element of their design, as opposed to something the owner needs to know and manually activate, unless it ties in with the natural behavior changes that would have things be opened up and breathing when nice fresh weather is in town.

    I liked their section on Masonry Heaters, too.. reminding me of a Rocket-Stove variant that just hit me the other day. Instead of building out all that masonry mass, to have the long exhaust/heat flywheel be built as an encasing water jacket instead, making the system possibly simpler and smaller. Better have good seals and good drainage, though!

    Useful reference for you, PDF warning
    I use a brine of 150g salt added to 1l of water, in strong plastic bottles, as a phase change buffer in my freezer. It melts around -10C so it keeps the frozen food cool enough when the power goes out. Helped me once this year already. Oh, that is also good for transporting frozen food in an icebox too.


    Thanks for the reminder. I keep forgetting that easy trick.

    Apartment buildings are a lot more efficient living spaces thermally speaking than standalone homes. They have much less wall and roof area for the number of inhabitants so the heat gains and losses per person are much less. Sadly everyone, including yourself by the tone of your last comment wants a standalone home in its own grounds which will by its nature take more power per person to heat and cool than an apartment will.

    The perfect answer to energy conservation in housing is giant apartment complexes with small windows and low ceilings. You can see pictures of this type of structure on old movies of the Soviet Union's new cities, the sort that are being abandoned since the events of the 1990s as the folks living there, thinking like yourself move out of the apartment blocks and into thermally less efficient standalone homes.

    I live in an tenement apartment in Edinburgh (built in the 60s -- the 1860s that is). The heating bills are low because we share floors and ceilings with other tenants (cooling isn't really a problem, not here in Scotland). The tenements are built in a row with no gaps between them so the east and west walls are also shared with other tenements further reducing heat loss.

    Very good points. I lived in apartments or multi-family dwellings for 90% of my adult life. My job kept me in urban/dense areas, oddly enough.

    Actually, that move was a system shock that eventually led me to read more about peak (insert resource here). I had no idea how far flung lifestyles had become.

    You must be referring to Stalinist architecture like this

    Single family can be fine with thick enough walls and good enough windows, but yes multifamily is a more efficient use of resources-when built thoughtfully. That requires proper envelope design linked with good air handling, and, though as you live in Edinburgh you might not be aware, good windows can work wonders for passive solar heat gain?- )

    I've still got a copy of the book, "THE $50 & UP UNDERGROUND HOUSE BOOK". It gives great low cost ideas on building a modest underground structure. Of course, building code does not approve, etc, etc, but if you are in a remote location - it gives you something to think about.

    Reply to all you good folk interested in thermal storage. I got interested long ago when I read Ted Taylor's great idea of putting two huge holes under central park in NYC. One would store summer heat, and the other would store winter cold. They would give heat and coolth to manhattan. Ted thought big, even tho his fame came from making little hydrogen bombs.

    ---gad! could it be that he was thinking up another use for those H2 bombs?? --Nah.

    I have a well insulated house, a big cold cistern, cooled by a heat pipe in winter, and a little water pump, heat exchanger, and fan. All this adds to fairly high level of comfort in hot sweaty summer days, and a lot of very easy dehumidification.

    As for winter, since we use a wood stove for many other things, we don''t worry about space heating or hot water. I have a big hot water tank up in the closet above the wood stove, so I can make a short hot fire in days like this when it is a bit chilly but gets a lot warmer in the afternoon. I can then use that hot water whenever I need some heat.

    We also made a little underground house for guests, worked wonderfully, but the ants ate holes in the roof, so we took the dirt off.

    And, why in the world don't they make fridges with a hole in the back so the thing could take in cold in winter with no or very little electricity? Seems so obvious.

    Excellent read Professor-great lead up to

    A short digression to contrast the miraculous energy density in fossil fuels: our 3 days of electricity storage at 30 kWh/day requires just 12 gallons of gasoline (1.6 cubic feet; 45 liters) burned in a 20% efficient generator (it seems like the other 80% is noise!). The Earth’s battery—a one-time gift to us—turns out to be vastly superior to any of these other “solutions” in terms of energy density and long-term storage, measured in millions of years. It will be sorely missed when it’s gone.

    especially since a drum of fuel and a generator loomed larger in my mind at every turn you took.

    Curious--about how long did it take for someone steeped in the material to bang off a gem like this post?

    No need to tell if it is a trade secret.

    I almost didn't read past the $100,000 price tag but I'm glad I did--of course extended out to 115 million US households and that comes up to a womping $115 trillion, a tad above the $25 trillion low ball number for the 'nation sized battery.' Didn't realize the big one was such a bargain
    ?- )

    Glad you liked it. Lead-acid is indeed the cheapest viable, scalable option. But it looks as if it can't be scaled all the way up, unfortunately.

    I'm keeping myself to a weekly schedule for Do the Math, and typically write 90% of a post one of the weekend days, then tweak and add over the next few days, mostly on my bus rides to and from work. I probably spend an average of 8-10 hours on a post. It's a pretty short leash, and a heavy demand outside my day-job activities. I think it's worth doing, but we'll see how long I can keep it up.

    You are doing a great job, please note that people like me take your work and spread it around all over the place. You are most certainly not wasting your time. I am also sure it is taxing on you. Lots of us appreciate it.

    PS. One of my regrets as I get to the end of my time is that I didn't properly thank all my very good profs I was so lucky to have had. Too dam young and oblivious. I hope they were wise enough to recognize that I was just a half baked kid, but might grow up enough sometime to recognize what they had done for me. I did, but awful late.


    What did you think of my comment below?

    Just exploring thoughts here. Convert sunshine to electricity at 15%, then at 50% for electrolysis to get hydrogen. Then get CO somehwere (not sure where from though) and use Fischer Tropsch at 60% to produce Cn H(2n+2). Then we have diesel or anything else you want. Overall efficiency around 3-4% of incident sunlight, maybe quite a bit less when you factor in every input but that's still not too bad. Of course not as cheap as natural gas gushing out of the ground but who said energy in the future will be cheap. Say this costs 4X more than today, well that's not horrendous considering how many efficiency improvements we could make.

    Power interruptions from grid are so rare that the effective efficiency will be close to 15% minus any losses of converting to A/C. Most of us store back-up power in a 9V torch battery and a few candles. Should be enough petroleum around to make a few billion candles for home back-up lighting.

    That's from 2007, when they were planning a prototype. I managed to find something from 2009, where they've successfully tested it:

    Anybody seen anything more recent?