Hydrogen Won't Save Our Economy

anaesthetica writes "Physorg.com is featuring a story asserting that hydrogen is economically infeasible as a replacement for our current energy sources. The premise is that isolating and converting hydrogen into a usable energy source takes up a great deal of energy to begin with, and that subsequently converting that hydrogen fuel into usable energy results in an overall efficiency of only about 25%. Apparently, the increasing scarcity of water is going to make hydrogen too costly and just as politicized as oil." From the article: "[Fuel cell expert Ulf Bossel's] overall energy analysis of a hydrogen economy demonstrates that high energy losses inevitably resulting from the laws of physics mean that a hydrogen economy will never make sense. The advantages of hydrogen praised by journalists (non-toxic, burns to water, abundance of hydrogen in the Universe, etc.) are misleading, because the production of hydrogen depends on the availability of energy and water, both of which are increasingly rare and may become political issues, as much as oil and natural gas are today."

Comments

Well, yeah, wasn't that obvious?

[Colin Smith]

The hydrogen economy was an idea dreamed up by those with a vested interest to divert attention and money away from more promising and immediate technologies which compete with their own investments. Still, the government got to spend lots of money.

Re:hydrogen may be inefficient BUT

[frankzeg]

As some one who works with hydrogen on a daily basis let me assure you that it is a true pain to deal with as compared to many other gases. It diffuses through many polymers and leaks are extremely dangerous due to its wide combustion mixtrue ratio range. WIth an invisible flame you can walk right into a large hydrogen fire. To get decent densities for storage you are working with either very high pressures or liquified H2. Both of these are problematic. One imposes hydrogen embrittlement issues, large heat of compression losses and many materials are useless and the other demands exquisite thermal control and imposes many other materials limitations. Hydrogen is a great fuel but only for certain uses and I would not say that everyday transport is one. It MAY be acceptable for fixed-base use in industry and less possibly in homes.

Transport batteries ( I think we all agree that is what we are discussing here) require a few things to be practical: low cost of materials and ease of fabrication, high energy density, ease of movement of the material from one vessel to another and finally ease of synthesis and also conversion efficiency. Non-toxicity is important as is the effect on the atmosphere. There are very few materials that can match or better liquid hydrocarbons.

There is one candidate that should at least be considered. Nitrous Oxide. N2O is a saturated fluid under about 750psia at room temperature and it has a density the same as hydrocarbons. This means that vessels to store it are efficient. It is non-toxic although it is an anesthetic gas. It is very safe to handle and compatible with nearly all materials. This means that the devices to handle it are cheap to make. It is a liquid so heat of compression losses for movement are minimized. If it leaks it has a distinct odor and will generally not pose an explosion hazard- at least compared to H2.

N2O is a monopropellant- in other words it will decompose to N2 and O2 when passed over a heated catalyst. It reacts very completely and almost no NOx species are produced- good for pollution. Better still it has a high flame temperature which makes for high thermodynamic efficiency. So a turbogenerator running N2O does not have to have a compressor- it can work at least part of the time off of the storage tank source pressure. Heat from the environment or directed waste heat from the exhaust can help keep the remaining N2O warm and vapor pressure high. N2O has a decent energy density but more importantly you can add any fuel and increase the power release enormously. So you power with N2O when you can and add fuel when you need to accelerate. The power increase is rapid and significant.

It does have problems though- synthesis is complex and not presently at large scale. What would be great is to develop a catalytic system that could take atmospheric N2 and O2 and under proper conditions directly synthesize N2O which could then be stored. Sounds hard to me but you never know. In any case there is no shortage of the precursors. It is however a nasty greenhouse gas. This could be its worst issue- lareg releases of unreacted N2O could be worse than CO2. But at least these are accidental and incidental- not part of everyday operation.

Anyway it is something to ponder. I always thought that a N2O vehicle with ethanol fuel assist sounded pretty good- and what a party car!

Re:FRAUD Alert?

[Cyno]

Yes, but I can still extract Hydrogen from mud, so what's your point? Why are you commenting on the lack of clean water for hydrating animals as if its relates to energy economics? Its a completely different problem altogether. Once the energy problem is fixed, then I think getting clean water everywhere will be a lot easier by truck than by foot, don't you?

So by your logic its too hard to distribute clean water and too hard to extract "industrtial levels" of hydrogen from probes in the middle of the ocean, so what, just die when the oil runs out? Gee thanks, brilliant. Got any other ideas?

Re:House of Cards

[Rei]

Hydrogen is not an alternative fuel. That's the problem. So far, whatever source of energy you're using to make the hydrogen - electricity, natural gas, etc. - can be better used directly instead of pissing away half of it using hydrogen as an intermediate.

You seem to be missing the two fundamental points of a hydrogen economy.

1) A hydrogen economy is not bound to a specific liquid fuel. Ultimately, a hydrogen economy is an electric one. Not many are predicting "peak electricity" any time soon.
2) A hydrogen economy is very efficient. That is, to say, electric vehicles (which is what hydrogen-fuelled vehicles are) can easily recover energy, electric engines are very efficient, fuel cells are up to ~70% efficient, electrolysis of water is ~90% efficient, etc.

Of course, in the mean time, until thermolysis of water (say, from nuclear power) or farmed hydrogen (say, from genetically engineered bacteria) is available, producing the hydrogen is a somewhat wasteful stage that's reliant on natural gas. Only "somewhat", however. Natural gas reforming produces H2 and CO. CO can be burned for heat. As a result, apart from incomplete combustion, all of the energy of the natural gas either goes to H2 or heat. Heat can be used to do work. Indirectly (subject to carnot cycle losses), it can generate power. More usefully, however, is it can heat processes that need heat inputs -- industry or even home water/house heating. In such a case, you only "lose" a tiny amount of the natural gas's energy.

Of course, even if you consider all of non-H2 energy wasted, as this article does, you're left with the following possibilities:

1) 30% efficiency on your typical ICE gasoline engine.

OR

2) 25% efficiency on your typical natural-gas derrived hydrogen engine, which is automatically a "hybrid" and can thus save power by regenerative braking. And, since it uses natural gas for the hydrogen, which is currently more available than oil, it reduces stress on the oil market. If natural gas prices rise too much, pressure on natural gas markets can be allieviated by switching from natural gas power plants to coal/nuclear (as happened with the oil-driven power plants in the 70s).

Is the second option really that bad -- present day? Especially with some of the new high-density hydrogen storage systems hitting the market? I think not.

As an aside, I ran into an interesting proposal for hydrogen storage that costs 1/3 as much as conventional storage tanks: commercial-scale wind turbines. They're huge hollow shafts. The extra cost to make the turbine able to hold hydrogen is something like 85k$, and an equivalent-sized tank costs something like 250k$.