Guest Post by Willis Eschenbach
As a result of my post on energy storage entitled Getting Energy From The Energy Store, a few people brought up the idea of replacing our current energy sources such as gas and oil with hydrogen (often written as H2, because two hydrogen atoms make up one hydrogen molecule).
You see this on the web, that we could power our civilization on hydrogen, convert all the trucks and buses to run on hydrogen, they call it shifting to a “hydrogen economy”… and why not? You can burn hydrogen just like natural gas, you can run an internal combustion engine on hydrogen, what’s not to like? Here’s a typical intro to an analysis:
A Comparison of Hydrogen and Propane Fuels.
Hydrogen and propane have long histories of being used as fuel. Both fuels can be used safely if their physical, chemical, and thermal properties are understood and if appropriate codes, standards, and guidelines are followed. Although the properties of hydrogen have been compared to those of propane and methane, these comparisons were made to facilitate appreciation of the physical and chemical differences and similarities among these fuels. It is not possible to rank these fuels according to safety because plausible accident scenarios can be formulated in which any one of the fuels can be considered the safest or the most hazardous.
So what’s wrong with this comparison, between hydrogen and other competitive fuel sources like propane and methane?
What’s wrong is that people misunderstand hydrogen. Unlike say propane or methane, hydrogen is not an energy source. There are no hydrogen mines. You can’t go out and drill somewhere into a deposit of pure hydrogen and bring it back home to burn.
And why can’t we mine or drill for hydrogen and bring it home and burn it to power our cars?
The reason we can’t mine and burn hydrogen is simple … it’s all been burnt already. The nerve of nature! I mean, people are always warning that we’ll burn up all the fossil fuels, and now we find out that nature has already gone rogue on us and burned up all the hydrogen …
Figure 1. Burnt hydrogen, showing the hydrogen and oxygen atoms.
Most of the burnt hydrogen we call “the ocean”. Another bunch of burned hydrogen we call ice and rain and rivers and lakes. But there’s no hydrogen that is available for drilling or mining—it’s all bound up in other compounds. And as a result, hydrogen is not a source of energy—it is merely a way to transport energy from Point A to Point B.
[UPDATE April 17, 2023: It’s been pointed out to me that there is one small hydrogen well in Africa, and that there is hydrogen produced naturally by reactions with water in the depth of the earth. However, as far as we know currently, it only collects in commercial quantities under very unusual conditions. Most is constantly escaping in tiny seeps. In addition, the global annual geological H2 production, not usable production but total production, is estimated at 23 Tg/year, which contains energy equal to less than 1% of the world’s annual energy usage. A possible future energy source for the globe? Seems doubtful, but it’s early days, time will tell.]
And this in turn means that the main competition to hydrogen, what we should be comparing it to, is not natural gas, nor propane as the quote above says, nor any other gas.
Instead, the main competition to hydrogen, the true comparison, is to electricity, which is our current means of transporting energy. Saying that we could “power our civilization on hydrogen” is as meaningless as saying we could “power our civilization on electricity” … neither one is a source of power, they’re just different ways to transport energy around the planet.
This is not to say that hydrogen is not useful, merely to clarify what it is useful for—transporting energy from one place to another. It is not a source of energy, it is a way to move energy. This distinction is very important because it lets us make the proper comparison, which is not comparing hydrogen to propane as they did above, but comparing hydrogen to its real competition—electricity.
Now, compared to electricity as a means of transporting energy, hydrogen suffers from a number of disadvantages.
The first disadvantage results from what I modestly call “Willis’s Rule Of Small Stuff”, which states:
It is far easier to move electrons than to move molecules.
This rule has ramifications in a number of fields, particularly the transportation of energy. For example, consider the difference between moving a large amount of energy on a constant basis over say a hundred miles (160 km) by the two competing transportation methods, electricity and hydrogen.
For electricity, you just have to move electrons. So you string a pair of copper wires up on poles from Point A to Point B, and … well … that’s about it. You hook one end to a generator of electricity, and a charge appears at the other end of the wires. There’s not much leakage, not many problems of any kind. The system is robust and relatively safe, and able to withstand storms and temperature extremes.
Now, consider moving the same amount of energy as hydrogen. For that, you have to move molecules. First off, you need a pipeline. Now, we’re all familiar with pipelines for moving energy. The trans-Alaska pipeline is a fine example. Pump oil in at one end, add some pumping stations along the route to keep it moving, and oil pours out the other end.
Hydrogen, though, is a very difficult beast to pump through a pipeline. To start with, hydrogen has very, very low energy density. So you have to pump a huge amount of it, about 4,000 times the volume of gasoline or oil for the same energy.
Next, hydrogen is incredibly sneaky. Do you know how a rubber balloon filled with helium gradually loses its helium over time? The helium is small enough to go through holes in the rubber balloon, tiny holes that are too small for air to pass through. Well, hydrogen is even worse. It can escape right around a piston in a pump, and run happily out through the pipe threads in any pipeline connectors. It requires special gas-tight connections from end to end of the delivery chain. You can’t just stick the hydrogen pump nozzle into your gas tank like you can with gasoline or diesel. So moving the molecules of hydrogen turns out to be a much, much harder problem than moving the electrons with electricity.
The second disadvantage of hydrogen as a means of transporting energy is the low energy density mentioned above. In general, the energy content of fuels varies with their density. So for example, diesel has more energy per liter than gasoline, which is lighter. And alcohol is even less dense, so it contains less energy per liter than either gas or diesel.
Now, consider hydrogen gas. Figure 2 shows a chart comparing various materials regarding energy density in two different measures—megajoules per liter (MJ/L), and megajoules per kilogram (MJ/kg).
Figure 2. Energy density of selected materials. Vertical scale is in megajoules per litre, and the horizontal scale is in megajoules per kilogram. Hydrogen is at the lower right. Click to embiggen. SOURCE
This leads to an oddity. Hydrogen gas has a huge amount of energy per kilogram … but almost no energy per liter. Gasoline holds about 35 megajoules per liter (MJ/L). But even compressed at 700 bar (about 10,000 psi) hydrogen has only about 5 megajoules per liter. That means that you have to move a lot of hydrogen, or pack a lot of it into a car or truck fuel tank, to have enough energy for practical purposes.
Now folks are always claiming that this problem will be solved by adsorbing the hydrogen onto the surface of an as-yet-unknown sponge-like substance from which it can be recovered as hydrogen gas by heating the substrate. But that can’t possibly be as energy-dense as liquid hydrogen, and liquid hydrogen has only a measly ten megajoules per liter. So adsorbing it will not solve the problem.
Nor will liquefying it, seeing as how you have to keep liquid hydrogen at about 240 degrees C below zero (-405°F) … not practical.
And that means that if someone wants to store much energy, say at a hydrogen fueling station, well, they’ll need a whole lot of high-pressure tanks with special fittings, and they’ll need to be about six times as large as the corresponding gasoline tanks to contain the same amount of energy. Or if they are storing the hydrogen adsorbed onto the surface of some as-yet-undiscovered material, they won’t need to be high pressure, but they’ll need to be even bigger.
The third disadvantage of hydrogen as a transportation medium is safety. Yes, electricity is dangerous, of course. But electricity isn’t flammable, and hydrogen is extremely flammable. Hydrogen has an unusual quality. Most fuels only burn when there is a certain ratio of fuel to oxygen. But hydrogen will burn whether it’s a little hydrogen mixed with a lot of air, or a lot of hydrogen mixed with a little air. Not only that, but the hydrogen flame is colorless, smokeless, and invisible in sunlight … a very bad safety combination.
The fourth disadvantage of hydrogen is something called “hydrogen embrittlement”. Here’s a crazy fact. Hydrogen molecules are so small that they can leak out through solid steel. It can either react with steel, or it can leak right through the steel. But that minuscule slow leakage is not the real problem. The real issue is that hydrogen penetrating into and through the metal lattice weakens the steel, fatigues the metal, and decreases fracture resistance. In the long run, it can embrittle solid steel to the point where it cracks all the way through after only a slight impact.
The final disadvantage of hydrogen as a transportation medium is that after using hydrogen to transport energy from A to B, it is hard to convert the hydrogen back into other useful forms of energy. For example, electricity can be used to drive a crankshaft, heat a cup of tea, shoot a railgun projectile at supersonic speeds, energize a magnet, wash my clothes, power a laser, propel a train via linear induction, light up a football stadium, split water into hydrogen and oxygen, charge my computer’s battery, or to drive a chemical reaction against an energy gradient.
Out of all of those uses, hydrogen can drive a crankshaft with very low efficiency compared to electricity, and it can heat a cup of tea … yes, you can use hydrogen in a fuel cell to convert it back to electricity, but that kinda defeats the purpose.
I mean, isn’t it rather goofy to use electricity to create hydrogen, transport the hydrogen, and then convert it back to electricity??? What’s wrong with this picture? Why not just use the electricity directly?
All of this taken together, of course, is the reason that our civilization did not adopt the use of hydrogen as an energy transportation medium, and we settled on electricity instead … because, well, it’s kind of a no-brainer. For just about any purpose you can name, including transporting energy around for powering cars and trucks, hydrogen is well down on my list of good candidates.
Now, if I can just find out who burned up all the hydrogen and didn’t save it for the grandkids like Death Train Jim Hansen advised us to do …
w.
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Scott Scarborough says:
July 1, 2013 at 7:29 am
There seems to be alot of expertise in the comments of this blog. I have a question. What about spliting (cracking) ammonia to get hydorgen (NH4).
Since most ammonia is made by the Haber process which involves reacting N2 and H2 and the H2 is produced by steam reforming of hydrocarbons this would be rather pointless.
Dear censor:
Another datum non gratum for you to hide .
Willis is doubly wrong in categorizing fossil fuels as containing “burnt hydrogen” —
“Most of the burnt hydrogen we call “the ocean”. Another bunch of it is in the form of hydrocarbons such as propane and natural gas.
Because :
1. Carbon does not burn in hydrogen .
2. While ‘burning’ by definition liberates heat, the reaction of carbon and hydrogen absorbs it.
To Matt:
The Ariane 5 uses liquid hydrogen in the first stage. The Chinese
(it figures, doesn’t it?) use UDMH / N2O4 for the first stage of the Long March 4
rocket–still in service. However, the Long March 5, which last I looked was still in
development, is supposed to use kerosene in the first stage.
Chris:
That is why I said most, not all. Because there is many factors, payload size, rocket shape, design, weight distribution, where the rocket is launched. How high and how fast it needs to go etc.
In general, RP-1 (and its substitutes) are used because of a high energy content, and lack of special needs. ( Hydrogen needs special tanks, that are insulated and built for extreme pressure which means heavier. Which in a rocket weight means everything ). There are many sources and ways to do it. Solid fuels, mono fuels, hybrid ( different types ie gas, liquid, solid), liquid etc. There is no real gold standard. But most just copy what works.
That said, I am no NASA scientist, just an amature building a liquid propelled rocket lol
We forgot to mention hydrogen embrittlement as a disadvantage.
Hydrogen is in the metals column of the periodic table, and like mercury soaking into a penny, hydrogen can soak into the metals transporting it, especially iron or steel. This makes the metal more brittle, hence an accident waiting to happen.
Scott Scarborough says:
July 1, 2013 at 7:29 am
“There seems to be alot of expertise in the comments of this blog. I have a question. What about spliting (cracking) ammonia to get hydorgen (NH4).”
Ammonia is actually NH3, the NH4 is called ammonium. To make hydrogen from NH3 is much less energy costly than making hydrogen from water (standard enthalpy of formation for ammonia gas is -45.9 and -80.8 for aqueous, for liquid water -285.8 kJ/mol), but water is obtained at virtually no cost and can be easily handled, so the cost of the hydrogen production from water using simple electrolysis would be probably much lower in case you have unexpensive energy source for it. Ammonia costs several hundred dollars per ton and needs tens of thousands of cubic feet natgas to produce it – for example: The source for ammonia on the market (which purely theoretically also could be used for hydrogen production) could be for example anhydrous ammonium nitrate fertilizer, but it is about 800$/ton and needs ~33500 cubic ft natgas to produce it in the first place. (33500 cft natgas contains 34521 MJ – which is equivalent to the energy in 7.671 tons of liquid hydrogen…which you never can get from 1 ton of ammonia, because simply it is not there 😉
Without the unexpensive energy source the hydrogen production for purpose of energy storage anyway makes no sense neither from water nor ammonia.
Just add hydrogen to finely-divided nickel in the presence of a secret catalyst and the proper electrical waveform and voila! Energy Catalyzer-styled cold fusion!
By turning H2 into He in a crystalline metal lattice, you’ve got one of the most powerful, safest, and least contaminating energy sources known to man.
That will be your “hydrogen economy”. And you’ll only need grams of the stuff.
Scott Scarborough says:
July 1, 2013 at 7:29 am
sorry I meant of course cubic meters of liquid hydrogen not tons. Sorry for the mistake.
Good article overall W. When looking at water, hydrogen is only a means of storing energy (and transporting). Starting with hydrocarbons, one can extract the carbon and be left with a hydrogen energy source. However, the gain in energy per mass tends to be offset in most cases by other problems. Not only is the hydrogen atom tiny so it can leak through just about anything, it is also capable of moving into the container walls and this tends to turn metal walls brittle. Hydrogen can feed fuel cells so stripping down the hydrocarbons into hydrogen atoms for direct conversion to electricity. So far though, I’ve never seen a fuel cell capable of generating anything close to the amount of energy it takes to make one – or put another way – it costs far more to make than the value of the energy is worth except where no other source is available – like manned space missions.
As for the safety, pressures must be very high, almost anything leaks, concentrations of something like 3% to 97% explode, and a flame from a burning tank may not be visible to the eye. Having pressure tanks or pipelines become brittle and fragile further add to the problem. In other words, if we had a source of hydrogen (and available carbon), we’d probably be better off converting it to methane for transportation. LOL. Since the hydrogen atom is so small and the problems exist due to its size, there is a good possibility that the best solution to hydrogen’s problems is to make it into a larger molecule – like methane.
Electricity is nice but you cannot store it effectively. It transfers fairly readily over wire but you have to use it when you produce it. Fortunately, it is readily produced by generators running with fuels like natural gas, coal, or diesel and by nuclear power reactors so we are not limited to simply the supply of fossil fuels.
“…using hydrogen as an energy source.”
——————————————–
Oh the humanity!!!
Another advantage of electricity is that it can be used to generate hydrogen and oxygen from water. Then you can reburn the hydrogen and oxygen to produce electricity. With 100% efficiency you have a perpetual system producing nothing. I think we are much better off using those fuels that nature has stored.
The point about those damned windmills is that the pollies insist we have them. Having got them, sometimes they produce power, sometimes they don’t. When they do, sometimes they produce more electricity than we need. This is ‘waste’ energy and since it would otherwise be discarded it comes near-free. Electrolysis of water is from 70 to 77% efficient – losses occur in resistance, and probably some in impedance. So you have a source of hydrogen and oxygen, the latter being discarded unless you can sell it.
Now, storing hydrogen at high pressure is problematic as you have to expend energy in compressing it, and as people have pointed out it leaks, and makes metals brittle. If you store it at low pressure, just a lb or so above atmospheric, the energy used to compress it that much is small, and at low pressure it will not force into metals so easily, less embrittlement. It is possibly feasible to find surfaces which will not absorb the gas – glass, perhaps, so a structure coated with glass may be not subject to embrittlement. And if you store it with a view to using it within a few hours or so you are not really worried about leaks. If you store the hydrogen when there is surplus electricity, and use it to power a boiler or turbine when electrical demand is high then you are reducing your peak load generation requirement.
Yes, windmills are inefficient and costly and not viable as compared with coal or uranium fuels. But if you can shift the surplus energy via a hydrogen separation and storage system to a time when it is needed you could well be improving the finances of a wind/coal power system. As someone put it re the storage of “coolth” you are shifting cheap electricity from a time when you cannot otherwise use it to a time when you can sell it at a price which could cover all the costs in so doing and make a profit. Better than pumped storage, you don’t need a nearby mountain.
And this applies just as much to sunlight, indeed, given that in many inland locations (think Australian inland) you can pretty well guarantee plenty of sunlight, it is plausible that the above process would work even better.
This is a silly post. Start with this: It is far easier to move electrons than to move molecules.
Lots more energy is moved in the form of molecules than electrons, as in oil tankers (ship, road and rail). oil and gas pipelines, coal barges.
The rest of your article consists of showing that, if the technical difficulties can be solved cheaply, they haven’t all been solved yet. Or the odious “H2 is not a panacea”.
Hydrogen is not an energy source? Neither is an automobile battery, which was the stimulus for the last post.
One little problem of hydrogen storage was omitted… that of spontaneous ignition.
Efficient storage and transport/distribution of hydrogen does indeed require pretty high pressures, and the hydrogen does have a nasty inclination to escape, especially at those high pressures. Hydrogen is fairly unique, in that when released from high pressures it will heat up instead of cool. The effect is significant enough that leaks from high pressure hydrogen systems can ignite with no other source of ignition. And with a flame that is really difficult to see in the best of conditions, you’ve got the potential for some really serious problems.
The logistics and economics of a “hydrogen economy” are simply mind-bogglingly difficult. Even if you can assume away the worst of the materials-handling issues, hydrogen can only work if the energy needed to produce it is really, really cheap. And at that point an all-electric economy starts looking very attractive, including even those big batteries to run our cars.
Scott Scarborough says:
July 1, 2013 at 7:29 am
There seems to be alot of expertise in the comments of this blog. I have a question. What about spliting (cracking) ammonia to get hydorgen (NH4).
I should have mentioned above that another major use of Hydrogen is to manufacturer fertilizer. Mostly, natural gas is used along with steam to produce Hydrogen in a process that is called steam reforming. Naphtha can also used instead of methane, but I have never see such a plant. That does not mean they do not exist.
Without methane (natural gas) we would not enjoy the food production that we currently enjoy.
Of course the downside is that some of that methane is used to make fertilizer that is used in abundance to grow corn, which is used to make ethanol, and all the runoff is making a dead zone in the Gulf of Mexico. That’s abuse of natural resources.
Hydrazine is nasty; but the Titan missile used it in its first stage, and there are several other missiles that do so as well. It’s a heck of a reducer.
DaveK says:
July 1, 2013 at 9:37 am
One little problem of hydrogen storage was omitted… that of spontaneous ignition.
Efficient storage and transport/distribution of hydrogen does indeed require pretty high pressures, and the hydrogen does have a nasty inclination to escape, especially at those high pressures. Hydrogen is fairly unique, in that when released from high pressures it will heat up instead of cool. The effect is significant enough that leaks from high pressure hydrogen systems can ignite with no other source of ignition. And with a flame that is really difficult to see in the best of conditions, you’ve got the potential for some really serious problems.
It’s interesting that for many years the UK supplied a gas for domestic use which was mostly H2 (~55%) mixed with CO. This was supplied at low pressure and explosions weren’t a hazard, the greatest risk was poisoning by the CO, in fact the gas was a frequent means for suicide. When replaced on a national scale by natural gas explosions became a major factor necessitating a national program to line the old pipes which were the source of leakage. One advantage of hydrogen is that although it has wide explosion limits it diffuses away to a safe composition very rapidly.
In Wyoming we have a substantial number of gas wells that produce H2S. This is separated from the “natural gas ” components, and then typically flared. However, flaring it leads to bad air quality, and there is some idea now of instead reforming it to separate sulfur from hydrogen. This would provide a source of H2, but only a very limited one.
Re: “reducing your peak load generation requirement.” this relates to the fuel you would have to burn to get the power you want, not to the actual boilers and turbo alternators, which would be the same.
It’s always about energy density. That’s why solar and wind power will never, never, never be viable sources of power.
All of this taken together, of course, is the reason that our civilization did not adopt the use of hydrogen as an energy transportation medium, and we settled on electricity instead … because, well, it’s kind of a no-brainer
Hydrogen in the 1850’s powered all the lights and heat in New York city.
Using your context electricity itself is an energy storage medium.
When I was very, very young about 5 years ago I brought up hydrogen as a fuel source right here on WUWT. I learned enough in about 30 minutes from comments by engineers , and I am one albeit civil, to realise it was a really bad idea.
Thanks for the post Willis. People need to be reminded why they shouldn’t bark up this particular tree and spend their thinking more profitably.
As an energy source, hydrogen clearly is impractical with today’s technology. However, I don’t think it is unreasonable to expect that sometime in the not terribly distant future it will become feasible, with the development of fusion reactors that can power electrolysis, and with sufficiently portable cryogenics for transporting hydrogen safely as liquid. And given that we have at least 200-300 more years before fossil fuels are depleted, there should be plenty of time for this.
Sigmundb says:
July 1, 2013 at 4:31 am
Sigmundb, I fear you just skimmed my writing, since you missed where I talked about what you claim I “conveniently forget to mention”. I discussed exactly that, what you call “the lattice of suited materials”, saying:
So no, adsorbing the hydrogen does NOT give it an energy density in MJ/l comparable to gasoline, that’s not correct. That system of adsorbing the hydrogen in a lattice can never give an energy density greater than that of liquid hydrogen … and that is far below the energy density of gasoline.
And regarding the “oil mafia” and what fifty litres? of palladium might or might not do, you need to turn down the credulity control on your information input, Sigmund … there’s no free lunch when it comes to energy. In any case, the commercial source of hydrogen is natural gas … so the oil companies would like nothing more than for someone to find a way to run the planet on hydrogen plus palladium, they’d still be in the driver’s seat …
w.
Several commenters have pointed out the ability to store hydrogen at high density by bonding it to some sort of nanodot or nanorod. Carbon nanorods can be fabricated (and sometimes even found to be naturally occurring!) with hydrogen atoms attached in many locations along the rod. One popular configuration uses a nanorod comprised of 8 carbon atoms. Perhaps, one day, the various surface adsorption technologies may approach the storage density of hydrogen-loaded nanoparticles.
Some years ago I realized that my old Ford Explorer can run on this nanotechnology-based hydrogen fuel. It is liquid over a wide temperature range, can be easily handled by a lay person with no special training or tools, and has virtually no self-discharge rate.
My bumper sticker says-
This vehicle powered by hydrogen-loaded carbon nanorods
🙂
Comparing liquid hydrogen with electricity is completely off. Hydrogen is not a way to transfer enregy, it is a way to store energy for later use. And current electricity storage systems are not that much more efficient than storing hydrogen.
“It is far easier to move electrons than to move molecules.”
Problem solved, isn’t it? Just build me an electron tank, attach it to a car and we’re ready to go. Or not.
And mind you, with AC your electrons are not going anywhere and with DC they’re travelling at speeds of several millimeters per second. Fill a hose with tennis balls, then add one ball at one end. Immediately another ball will fall off the other end. Energy was transferred but balls did not travel very far. It’s the same with electrons.