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.
PeterF says:
July 2, 2013 at 3:21 am
Peter, first, thanks for a very interesting citation. However, I fear you’ll have to be more specific. The key with hydrogen is what they call “volumetric capacity”, the amount of hydrogen in grams per litre. The density of liquid hydrogen is 70 g/l, which is listed as their “Ultimate” target. I didn’t see anything in the citation that showed a greater volumetric capacity than that of liquid hydrogen.
It appears that their figures are “whole system”. That is to say, for liquid hydrogen they include the volume of the insulated tank. And that is a valid and useful measure, indispensable for real-world applications. That drops the volumetric density of liquid hydrogen down to around 35 g/l.
We, on the other hand, were discussing the volumetric capacities of the substances themselves (liquid hydrogen versus high-surface-area metal hydrides which adsorb/desorb hydrogen from their surface).
I was unaware of the research into aluminum hydride (AlH3)n. In solid form, it contains about twice the hydrogen content as liquid hydrogen. (it is 10.1% hydrogen by weight and has a density of 1490 g/L, giving a hydrogen density of 150 g/L. However, I wasn’t talking about solid hydrogen compounds. I was discussing the adsorption and desorption of hydrogen to and from the surface of such a compound. To do that, it can’t be in one solid block. It has to be shot through and through with pores and channels. This is both to give it the greatest possible surface area so that more hydrogen can go into and out of storage, and to provide channels for the hydrogen to pass to and from the surface. And that need for air channels and high surface area is bound to cut down on the volumetric capacity. That’s why I put the density of liquid hydrogen (70g/L) at the very top of the list … as have the people in your citation.
Regarding aluminum hydride, as a result, it appears that in a useable form, which they report as some kind of experimental “alane slurry”, the hydrogen density drops to about 50g/L, which is well below that of liquid hydrogen (70 g/l) itself. (It is also above the performance of liquid hydrogen if you include the volume of the dewar flask needed to store the liquid, which is not our topic but which is critical in the real world.)
So I fear my claim still stands, that regarding hydrogen storage for use as energy, liquid hydrogen contains the most hydrogen per litre. Well, except solid hydrogen … plus I learned about alane along the way.
Finally, all of their figures were lab results, not actual practical systems. Doesn’t make them less interesting or valid, just that they need to get discounted some for the real world.
Thanks again for a fascinating citation.
w.
Karl says:
July 2, 2013 at 8:17 am
Thanks for an interesting study. However, it doesn’t show what you claim. To the contrary, it shows that with the largest interconnected network studied, the continuous baseload was … well … zero. As you’d expect, because while the wind does blow all the time somewhere, sometimes its not blowing on any of your windmills. Same is true for coal plants. Sometimes they break down, nobody guarantees 100% continuous base load.
Instead, the study presented a curve in Figure 3 showing how much generation you could depend on for how much of the time. Coal plants are down for unscheduled maintenance maybe 5% of the time. If you want to be able to guarantee power 95% of the time, for example, with their selected sites you can only guarantee a measly 10% of nameplate capacity. Or to quote the study:
OK, by eye from Figure 3 I’d said 10% of nameplate capacity, they say 11%. Not the 33% you claim.
And even if were 33%, color me unimpressed … you talk blithely, for example, of providing a thousand megawatts of baseload from 3,000 megawatts of wind. A thousand megawatts, that’s a really big coal or hydroelectric plant. Typical large windmills are on the order of 3 MW, so you’d need a thousand of them … can you imagine the logistical nightmare of maintaining and replacing a thousand huge pieces of delicate machinery perched a hundred metres in the air? The Stanford folks totally left out that part …
To summarize: The study says that if you build a nightmare of 19 windfarms with huge interconnecting transmission lines covering five states, you can guarantee a whopping 11% of nameplate capacity as baseload, if you ignore the maintenance of wind turbines. To replace one 1,000 MW fossil fuel or nuclear plant, you’d need 10,000 MW of nameplate capacity, which is about 3,300 typical large wind turbines.
But wait, as they say on TV, it gets worse … typical area required for each turbine is about 250 acres per megawatt, so it will be spread out over two and a half million acres (a million hectares) of land, not counting the easements required for the high-voltage interconnection lines … good luck with that one.
Wind for grid-scale electricity only works in special situations, and even then only when subsidized.
w.
jkanders says:
July 2, 2013 at 6:38 am
To reforest Sahara would probably need a climate change which brings much more rein to the region, and I don’t think that is within reach of our technology.
I think it is. You just need enough cheap powersource for you to be able desalinate water for it. Then you plant trees which you irigate intensively and in turn they’ll keep the water in the ground. In Tunisia for example they have a tight law how many trees you must plant for you to be allowed plant crops between them. There’s 80 million olive trees and almost same amount of palms there, which are especially good for subdesert, because they have very massive profound roots, keeping the water. If you have water, you can expand this further into the desert and gradually also add other species.
You need 2.6 MJ to vaporize 1 kg water which had 20C before. I would not say you need the 4th gen. nuclear. For this the wast solar energy there could be used quite effectively and on the spot, you just must bring the sea water. Instead of electricity producing solar cells trees, which are quite costly, ineffective and with very limited life, you would use the simple mirrors an the solar energy for desalinization – you can get close to 100% effectivity, inject the water into the root systems and your benefit will be that you make the land between the trees arable so actually habitable – getting the resources to make your living.
Something like that actually happened last half of the century at the Djerba, although not using solar energy, where besides couple of villages was just desert. Now half century later the bulk of the isle inland is planted. Just have a look at the google maps. You can see the progress at the satelite photos and It is quite impressive. Also have a look around. If you want to change climate from the desert conditions, your first priority is to retain water in the ground, which is moreover quite sandy so very permeable. Best way how you can do it is to plant suitable trees as the date palms, which will also serve as windbreakers.
I think that instead of building megalomaniac solar powerplants for feeding Europe it would be better to develop the region for itself to the state before ancient Carthagins destroyed the forests. And the example from Tunisia shows it can be done relatively quickly even without our advanced technologies. Imagine, how fast it could be using it.
The bonus there is that under the dry Sahara there is the remnant after the forest there – the largest fresh water aquifer in the world. Although the water is definitely not enough to restore the forests, it can help you. Again, you can use solar energy on the spot to pump it out. Again, mirrors and stirling engines can do the job, you don’t need to bring the electricity powerlines, not even there, not speaking about the Europe. -Which anyway would be much better off not seeking the renewables development (which anyway hasn’t the capacity to substitute for the high fossil fuels consumption there, no way, and anyway only significant effect which it has here are the energy prices and declining food selfsustainability stemming from the biofuels mayhem), but the development of the real energy technologies as the 4th generation nuclear. It is about time. The CAGW nonsense should be over now when we look at the temperature record and the solar activity record. So now the Europe and whole the west should concern about the real problems as the fast depleting energy resources and what we do about it. Before is too late. Unsubstituted general fossil peak would almost surely lead to global malthusian catastrophe, most probably as soon as 2050, and the west, due to its high energy consumption would be the one part of the world hit most heavily.
tumefaisdubien says:
> Then you plant trees which you irigate intensively and in turn they’ll keep the water in the ground.
Oh-oh. Where I live, trees suck so much water from the ground that its loss causes destructive subsidence of the nearby buildings. I kid you not. I learnt that from my landlord, a plant scientist specialising in trees. I am surrounded by the stumps of huge trees that had to be cut to preserve the house.
All good points, Willis, but how about some balance? What about the advantages of H2 over electricity? For instance; You can use solar power to produce both, but only one can be burned in an internal combustion engine.
Further to my comment above, here’s the must-see video: http://www.switch2hydrogen.com/
Barry Cullen says:
July 1, 2013 at 6:22 am
——————————–
I scanned this thread looking for your contribution and was disappointed to find that you only offer pointless criticism. And that i do not understand.
I will not clarify my humble (on topic) points since they are contained in the contributing posts in this thread. And i expect it was my politic opinions that confused you; these being off topic will not be clarified.
tumetuestumefaisdubien1 says:
July 1, 2013 at 5:28 pm
Dan in California says:
July 1, 2013 at 4:19 pm
“H2 is a powerful greenhouse gas”
No it isn’t. H2 has no absorption band at mid-IR 288 K spectra. Moreover it has very short life in atmosphere, because it its highly reactive.
——————————————————————————-
Well, dang. I don’t remember where I got that, but you are right. Of course, the H2O(g) emitted has greater greenhouse properties than CO2, but nobody is stupid enough to try to regulate H2O emissions.
Willis, an excellent rundown on the problems of using hydrogen as a practical fuel. I know you are aware of metal hydrides/unit volume containing more than liquid hydrogen/unit volume. However, no one needs to lecture you on human ingenuity in solving problems (yourself being a rather good example), and some of the ones you have pointed out may not be problems in the future. Recent research with lithium hydrides carried in carbon fullerine structures have reached 6H atoms/atom of Li and apparently they have also considerably resolved the problem of high temp (several hundred C) needed for releasing the hydrogen from conventional metal hydrides. Here is some research going on seeking to solve the problems you raise.
http://techportal.eere.energy.gov/image.xhtml?id=423&techID=538
http://newscenter.lbl.gov/feature-stories/2011/03/14/breakthrough-in-hydrogen-storage/
I’ve been an ultra believer in the effectiveness of R and D for two reasons:
1) In the summer of 1957, as a logger in Jarvis Inlet in British Columbia (I was earning my tuition into engineering) we were shooting the breeze about the new space program. My fellow workers to a man protested by assertion that there was no question that man would reach the moon and beyond. Naturally wagering started and I recklessly bet $100 each that in 20 years man would accomplish this. When I got back to University that fall, I only had to wait a month before Sputnik 1 shocked (and thrilled depending on where you lived) the world. The belief got a tremendous boost when, without focusing on space (they were focusing on missiles), the US changed course immediately and after one failure in December, 1957 a successful launch into orbit was achieved in January 31st, 1958
2) I read about 30 years ago or so that IBM had a larger R and D budget than the entire R and D budgets for Canada!! Having a company whose business is making money spending all this money sealed the deal. My belief in the ability to find solutions is of the kind that if we were forced to run cars on ice cream, we would find a way. Oh, and I never collected on my remarkable bet.
”
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 don’t think there is all that much ammonia around which is naturally occurring compared to methane. Making ammonia to transport hydrogen means transporting a deadly gas that is a serious inhalation danger if it gets out. Methane burns but it’s not deadly when inhaled in moderate concentrations.
@ur momisugly Willis
Yes it is yearly averaged, not nameplate capacity. Regardless it falsifies the BS that wind cannot provide baseload power. 11% of nameplate where the average wind speed was 6.9 m/s — becomes (roughly) ~ 33% when the wind speed averages 10 m/s (like offshore) due to the fact that the power incident in wind increases as the cube of wind speed. e.g. 10 m/s wind has 3 times more energy than 6.9 m/s wind.
Nor does the study incorporate any of the myriad advances in energy storage that can be used for load levelling. But that is a discussion for another time. Lets just say that the adiabatic heat of compression can be very useful if applied correctly. We can also say that efficacious use of solar thermal energy need not be limited to high temperature concentrators.
After all, V1*P1/T1 = V2*P2/T2. As Messieurs Boyle and Charles were so astute to point out.
Karl says:
July 3, 2013 at 5:59 am
First off, you don’t necessarily get more baseload power with increasing windspeed. The amount of baseload is determined by the regularity of the wind, not the strength of the wind.
Second, when you have to install a hundred megawatts of wind to get 10 MW of baseload power, that means you will have to build another 90 MW of conventional power … run the numbers on that before you declare victory.
Third, offshore wind is the most expensive power commonly used. The maintenance of wind systems is bad on a good day—instead of maintaining one 300 MW power plant down on the ground where you can get at it in an indoor location, you have to maintain a hundred three megawatt power plants stuck a hundred meters in the air outdoors in the rain.
Now, under this new blindingly-brilliant plan, you suggest the same thing, except you advise spreading them out over five states to give baseload power … yeah that’ll help.
But that’s nothing compared to the same system offshore, where you have to take a freakin’ boat out to each of the one hundred power plants, get all your tools and gear off the boat, climb a hundred metres into the air, oil the bearings or whatever, climb back down, load your gear back into the boat, and head for the next one …
The crazy thing about the Stanford study is that they said “Well, baseload isn’t baseload, because 5% of the time you have unplanned outages, and then there’s scheduled maintenance.” Fair enough.
Then, when they calculated the windpower side, they assumed that there would be NO unplanned outages and NO scheduled maintenance on the windpower side … gotta love professors.
And offshore, the maintenance and repair side is an absolute nightmare. Consider that you need a gigantic crane to install or replace a wind turbine generator or turbine blade. Now consider replacing a broken turbine blade offshore … with a fairly constant wind blowing (hey, you picked the windiest spot around).
Just waiting for a calm day could take weeks …
Wind power is a pipe dream. Like solar, there is no place that folks are using grid-connected wind power without subsidies, and for a very good reason.
It’s just about the most expensive power source in the mix.
SOURCE
w.
@ur momisugly Willis
Firstly, the distribution of wind speed over time closely matches a weibull distribution about the average wind speed, so IN FACT, an increase in average wind speed WILL direclty lead to an increase in baseload power.
Second, you have to build 1000 MW of wind capacity to meet 100MW baseload, you need build nothing else. Now ask yourself “how much newly contructed nuclear capacity has come online Worldwide in the last 5 years, vs. how much wind capacity?” — the answer is 190,000 MW vs maybe 1 or 2 plants. Even at 11% nameplate, that a 20 fold advantage to nuclear.
Thirdly, why not utilize un-utilized flooded real estate, instead of co-opting perfectly good non-flooded real estate, more often than not creating a toxic waste dump (coal, gas, nuclear, – pick one it does not matter) — we have had 2 coal fired plant waste holding ponds rupture and spill.
As to the chart — it proves the point for wind. 10 cents per kilowatt hour — that’s less than the retail cost of electricity in every single US state. I can put a wind turbine up by myself, I can’t do the same with a gas or coal plant.
Off shore maintenance and repair = jobs.
Karl says:
July 3, 2013 at 10:31 am
We’re not talking about the distribution of wind speed over time. We’re discussing how much overlap in wind regimes there is between geographically separated areas, because that’s where you get your baseload.
In any case, you can’t solve the problem by waving your hand and assuming more wind. The Stanford study was placed where they thought the most wind was, you don’t get to just imagine higher winds to solve your problem.
Well, if all you want to supply is 100 MW of base load, that’s true. And in that case … all you need to do is ask why you’re paying for a 1,000 MW of capacity and only getting a tenth of that as base load.
I don’t understand this at all. Yes, more wind has come on line than nuclear in the last two decades … what’s your point?
Why not use wind on unused real estate? BECAUSE IT COSTS WAY MORE THAN ANY OF THE MANY ALTERNATIVES!
What chart are you talking about? My chart? It shows the normalized COST, not the sales price you are blithely comparing it to.
And yes, the costs are near to that of coal … unless you factor in the reliability, which you have to factor in. When you include that, as you just pointed out, we need to install 1,000MW of nameplate to get the equivalent of 100MW of coal power … which means that our windpower costs are about ten times what the chart says.
This is not just dumb, it is dumb squared. Read up on the “Broken Window Fallacy“, there’s a good fellow. You’re just exposing your ignorance with claims like that one.
w.
PS—I don’t understand the statement that
Gosh, I feel sorry for your disability, it must be tough to live with. Me, I’m considering putting in a gas power plant at my house for generation when the power fails (which given California’s green lunacy is happening more and more often).
But you say you can’t put one in by yourself, and you definitely have my condolences if that’s true.
w.
Willis E. said:
“the hydrogen flame is colorless and invisible in sunlight …”
A hydrogen flame is not colorless, but blue. And many blue flames, like those of methanol and carbon monoxide, and like methane flames often are, are invisible in sunlight. Same for flames of natural gas mixed with enough air for them to burn blue. Indy cars were required to use methanol through the 2006 season.
Since acetylene is more explosive than hydrogen and has a wider flammability range in both directions than hydrogen, I think the hazards of hydrogen are overstated.
It appears to me that the main debate on hydrogen should be on comparing to batteries for storing energy that gets used in a clean way where it gets used.
Donald L. Klipstein says:
July 3, 2013 at 7:17 pm (Edit)
You are right that indoors or in the darkness, hydrogen burns with a faint blue flame. But as I said, in the sunlight, hydrogen flames appear both nearly colorless and almost invisible.
You are free to think so. People who work with hydrogen are not nearly so sanguine … the difference in flammability is trivial (2.5%-82% for acetylene, vs. 5%-75% for hydrogen). But given a choice between the hazards of a 10,000 psi tank filled with hydrogen and a 300 psi tank filled with acetylene, I know which one I’d take.
One huge problem is that unlike many gases, hydrogen heats up when it escapes from pressure. Most gases cool when they expand, but not hydrogen. It can get hot enough to ignite spontaneously just from leaking … which means that in a 10,000 psi tank, even the smallest leak is a big hazard.
Is hydrogen less dangerous than acetylene? Depends on what kind of danger, better on some scales, worse on others, so overall I’d say about the same … but even if it were less dangerous, saying that something is “less dangerous than acetylene” isn’t saying much.
Storage? We’ve already been through this. The only way to store it is compressed, which loses 15% of the energy. It can’t be pumped compressed to the storage pressure, so every time you have to move it, you need to reduce the pressure and then pump it up again at the other end, with the consequent energy losses. It requires heavy expensive tanks. Even compressed it takes up six times the volume that an equivalent amount of gasoline would occupy. It leaks like a bitch through every tiniest hole, heck, the tank specs for hydrogen storage tanks for automobiles specify an acceptable loss of 2% per week. It passes right into (and at times through) metals, and embrittles them in the process. And it’s difficult to turn it into other useful forms of energy (chemical, etc).
Donald, I have bad news for you. There is no debate on using hydrogen for energy storage. There are very good reasons why nobody anywhere stores energy as hydrogen. We store energy in a wide variety of ways, from springs to batteries to pumped storage to thermal storage in phase changes to heat exchangers to compressed air to hydraulic storage to flywheels … but I’ve never heard of anyone storing energy as hydrogen in the real world.
Why not? Well, like I said … lots of good reasons, many of which I gave above.
w.
Robin Hewitt says:
If the only sensible way to store energy is to pump water up hill, maybe the windmills should be pumping water rather than generating electricity. Skip two inefficiencient energy conversions.
Electrical generators need to be run at constant speed and in sync with the rest of the power grid. This is in itself a complex engineering problem.
A wind driven pump can perform useful work over a wide range of wind speeds and does not need to be synchronised with any other pump.
If this means that a wind driven pump is a less complex machine than a wind driven generator then it should be cheaper to build and maintain.
Mark says:
July 6, 2013 at 10:02 am
Interesting thought, guys, and it would work. There are a couple of problems, however.
First, as you might imagine, the places with wind resources are of two kinds—flatlands, and mountain passes.
Flatlands are a non-starter for pumped storage … which just leaves the mountain passes. But if you’re already at the elevation of the mountain pass, the altitudes above you are going to be steep pointy mountaintops … again, very poor turf for pumped storage.
The problem with pumped storage is friction. Unlike electricity, where you’re just moving electrons, with water (as with hydrogen) you need to move the molecules. And although with hydrogen friction is one of the few problems it doesn’t have, with water friction is a huge issue. This is in part because friction goes up rapidly with pumping speed, and rapidly becomes the limiting factor. And this in turn means your reservoir wants to be right next to your pumping station, whether it’s windmills or not … and this is a very tough requirement, very few sites have that possibility
So while you are definitely on the right track, cutting out two lossy energy transformations, the logistics are still working against you.
Thanks for your comments,
w.
jdallen,
I think it needs to be said that no one has it out for solar, wind, hybrids or hydrogen. It is just looking at it without subsidies like feed-in tariffs or creative uses of the word externalities, they just don’t pan out. Costs, intermittency, diffuseness and other factors make them impractical at this point for most situations. But if you live in the boondocks, solar panels and propane refer might make sense. If you want to spend $100,000 extra to save a few bucks in heating or lighting with a LEED or passive house that might work for you. I have no problem with a utility having a program to conserve energy to put off the next powerplant a few years, but I do with a government. It boils down to letting the technology stand on its own. If you need an example of my openness to such technologies, I give you my car. I’m tryng to figure out a way ,without using a window mounted unit, to vent the hot air in my car outside with a solar driven fan or at least circulate it enough to make a difference.