Aug 31 2011

The Coming Hydrogen Economy

Just a decade ago hydrogen fuel cells were going to change our world. We were going to have an infrastructure to distribute hydrogen and fuel cells in our cars that are so efficient and environmentally clean that you could use them to power your home.  So confident were the predictions of the “coming hydrogen economy” that car companies (like GM) banked on the technology, deciding to leap frog over hybrids. George Bush called for investment in the technology, and California’s govenator decided to get a head start on building the hydrogen infrastructure.

Now, a decade later, the hydrogen economy seems like just another false promise of future technology – like flying cars and jet packs. It turns out there were some non-trivial technical hurdles that needed to be overcome, and the assumption that they would easily or inevitably be solved was unjustified.

First, it needs to be recognized that hydrogen is not an energy or fuel source. There is negligible free hydrogen on the earth. That means that hydrogen has to be stripped from hydrocarbons or some other existing fuel, or hydrogen gas has to be made by putting the energy into it. So hydrogen is largely an energy storage system, not a source of energy.

The real killer to the hydrogen economy, however, is the storage mechanism of hydrogen. Filling a tank with hydrogen is problematic in that conventional tanks cannot hold much hydrogen. You can build tanks that can hold hydrogen under very high pressure, but then those tanks would be heavy. Further, there are significant safety issues in a car accident. Such tanks may be useful for stationary fuel cells, but not for cars.

So chemists have been searching for a form of bound hydrogen that has several desirable properties. The overall system has to be light, and has to be able to hold a high density of hydrogen (efficient in terms of both mass and volume). Further, it has to be able to both store and release hydrogen quickly, while still being stable. And it has to maintain these properties over a large range of temperatures.

Every now and then we read about a “hydrogen fuel breakthrough” that typically involves chemists coming up with a form of hydrogen that improves on one or a few of these properties. But we have not yet hit the “holy grail” of hydrogen storage for fuel – something that has all of these properties to an acceptable degree.

This is very similar to the battery situation – we keep hearing about breakthroughs in battery technology that typically represent improvement in one desirable property of batteries, but not others, or even at the expense of others. We need batteries that are simultaneously light, small, with a high capacity, and fast recharge and discharge rate, and many recharge cycles. What we hear about are batteries that may be impressive is one feature, but that are unusable in other ways – all we need is for the researchers to fix the limitations and the battery will be great. But of course, we never hear the follow up, because the limitations are not fixable (at least so far).

This post was prompted by yet another “hydrogen fuel breakthrough.” Researchers have figured out a way to make use of ammonia borane, (here is the original article) a stable solid that contains significant hydrogen. They developed a catalyst that will quickly release hydrogen from the material. They system is “air stable” and light weight.

This all sounds good. The paper primarily describes the new catalyst. The authors conclude:

This mechanistic insight may lead to the development of more efficient systems for AB dehydrogenation.

So – it sounds like a decent basic science development that might have an application in hydrogen fuel storage. But it also sounds like its a long way from developing an actual working hydrogen fuel storage system.

Still, that did not prevent the headlines from declaring yet again that we have a “Breakthrough in Hydrogen Fuel Cells.”

Don’t get me wrong – I think such advances are important, and this looks like good science. My real beef is the disconnect between the reporting of such research and the real implications. It does seem that often the researchers are partly responsible, speculating freely to the press about the potential future applications of their research. Press releases are also guilty.

But it would be nice if there were more of an effort to put such research into a realistic practical context. Maybe then we would not have so many false dawns, like the coming hydrogen economy.

16 responses so far

16 thoughts on “The Coming Hydrogen Economy”

  1. PharmD28 says:

    1-2 months ago I read an article in time magazine about newer upcoming fuel efficient vehicles….they made mention of a honda fuel cell vehicle in test drive now and that it will release likely in 2015. The article made it seem that a zero emission and practicle vehicle was just in reach now….it appears that is a stretch…. surpirse!

    This sounds like the same problem you mentioned before about the human genome where society gets all excited about hyped up shorter term successes from science, then are let down and feel that science is a hype because of false expectations….

  2. rezistnzisfutl says:

    This brings up a good point about something that’s been somewhat bothering me lately, which I feel this article is an example of, is how scientific studies are reported. The public perception of science and its usefulness, as far as I can tell, is at a low point in the US, and for them to sort of “bait and switch” with headlines like that is irresponsible, if you ask me. It gives fodder to the denialists that science isn’t reliable, and those that are reporting studies aren’t always doing themselves favors by the way they report things.

    Don’t get me wrong, I think reporting on what is important and newsworthy should be done, but too often the media, and like you said Dr. Novella, the researchers, seem to display a disproportionate amount of excitement and end up reporting on relatively trivial things, I suppose to try and garner excitement for science, but which from all accounts I’ve seen, often backfires.

  3. Matus1976 says:

    The ironic thing is, we all ready have a great hydrogen storage medium… it is called carbon. When combined with hydrogen it creates a fuel that has a high gravimetric energy density as well as a high volumetric energy density! Hmm I wonder what we should call this hydrogen+carbon energy storage system, a liquid at room temperature that’s very stable and has a high ignition point… maybe a hydrocarbon?

  4. daedalus2u says:

    I don’t even see that this is such a great advance (but I could only read the abstract). This paper shows better H2 (a lot better) release from the same thing using a Ni catalyst.

    The figure of merit is moles H2/min*mole catalyst. For the Ni, that number is 13.2. For the Ru catalyst it seems to be ~ 0.02.

    Ni is ~$10 per pound, Ruthenium is somewhat higher, ~$180 per troy ounce or $2625 per pound (av). On a molar basis Ni is $58.71 per pound mole, Ru is $26,539.

  5. rasputin-bot says:

    I am far more cynical about the prospects for hydrogen than I am about batteries. In particular the storage problem is far more intractable than is generally acknowledged. It’s not just a lack of technology it is the basic physics. Consider the porous materials being designed to adsorb hydrogen and lower the pressure of storage. I remember reading a review which examined the thermodynamics of hydrogen adsorption. Even if a material was developed which could bind hydrogen at a satisfactory pressure at liquid nitrogen temperature, the enthalpy of adsorption (the heat released when the tank is fueled), would be sufficient to boil off several hundred liters of liquid nitrogen. Note that this is a best-case scenario, for a material which has yet to be developed.

    Chemical storage methods, on the other hand, are limited by the low relative molecular weight of hydrogen. If you look at this paper, you will notice that even though they successfully released more than 70% of the hydrogen stored in the material, the total weight % released was less than 5%. And this doesn’t even take into account the weight of the tank and the heaters required to release the hydrogen. And this when they are binding the hydrogen to boron and nitrogen: if you look at a periodic table you will notice that there aren’t a whole lot of lighter elements out there. And don’t get me started about how you would “refuel” a chemical hydrogen storage tank.

    Battery development may be depressingly slow, but in my opinion hydrogen fuel cell research (at least for cars or other portable applications) represents a fundamental failure to accurately gauge the plausibility of any practical solution being found.

  6. Bronze Dog says:

    I remember being really excited in my younger days about all the various alternative fuel cars, probably with similar fervor to the days when people dreamed of those jetpacks and flying cars.

    It’s mostly worn off these days, especially with regard to hydrogen, when I put some thought and a little research into the ‘well to wheels’ processes. If, for example, you use electrolysis to make free hydrogen, why not just use that electricity to charge a battery and cut out hydrogen as a middle man? More steps would reasonably imply more energy lost to entropy.

    Right now, I think my higher hopes are on biofuels and batteries, but I try to keep them at sane levels. We definitely need to find something better.

  7. PharmD28 says:

    Hell, at this point I would fall over backwards if I could buy a diesel minivan – probably would get like 30mpg avg. At least I have my diesel wagon though 😀

    Have you all done much previous discussion on this site about electric cars, hybrids, and such? Gonna check it out when I get some time.

  8. robm says:

    While I’m a big fan of fuel cell technology, right now hydrogen cars seem as feasible as flying cars. Besides storing the hydrogen, the fuel cells that are practical for use in cars are very expensive, and there is currently no proven method of creating large quantities of H2 that doesn’t create a lot of CO2 in the processes. Hydrogen or electric cars will only make sense if electricity production is green.

  9. neilgraham says:

    I really appreciate this article. The one thing that keeps me interested in this blog – and, to a large degree the SGU – is the honesty of the presenter demonstrated by his willingness to critique ‘science’ as well as expose psuedo-science. The scientific method at work!

  10. nybgrus says:

    I had a roommate in college once who was from New Zealand doing an exchange program for his PhD work on fuel cells. He was very much of the same opinion – it is a bad middleman to use hydrogen for fuel cells of cars. One other esoteric consideration was hydrogen escape. Lets say we do have some perfectly green way to make electricity (say, great solar tech or something) and we hydrolyze water like crazy to be an energy storage medium and power the world with it. There would inevitably be leaks, accidents, and loss no matter how good the process was. The reason hydrogen is so rare to find on earth is because it is so light it readily escapes our atmosphere. So imagine a century or two of the world being powered through hydrogen via our water supply on earth and a (small) fraction of that escaping into space via hydrogen, never to return to the water cycle. We would literally be evaporating our planet. Although, it may end up being a way to combat rising water from global warming 😉

    Just a random thought.

    @d2u: I have institional access to the full article. I am not sure what the ethics/legality would be, or how exactly we would accomplish it, but I can in theory get you the full article if you really want to read it. Perhaps save it as a PDF and email it to you via your blogspot?


  11. daedalus2u says:

    You could mail it to me via my corporate email through my company,

    There is an email address for me there there.

    The real problem with hydrogen is that is is so dangerous, it has such a low ignition energy and it is such a small molecule that it leaks through any elastomer. It is nothing like any other gas. Air is trivial to seal compared to H2. So is natural gas. All connections would have to be metal-metal seals.

    You wouldn’t be able to take H2 fueled vehicles into below ground garages, into tunnels, or into garages attached to houses. It would be too dangerous.

  12. daedalus2u says:

    I misread the abstract. The paper Dr Novella reported on is about the anhydrous release of H2 from NH3BH3, the paper I cited is about the catalytic hydrolysis of NH3BH3 + 2H2O –> NH4BO2 + 3H2.

    I will read it more carefully.

  13. Daedalus does raise another feature of such technology I did not raise above – the cost and the materials, which includes disposal. It would be nice if our batteries and fuel cells were not made of rare and expensive materials, or toxic materials that will clog our landfills.

    So yet another feature to consider.

    It’s not easy to come up with a technology that meets all the requirements to a reasonable degree, and any one feature can be a deal killer.

  14. tmac57 says:

    Concept for a new magazine:

    ‘Popular Science in Perspective’

    What do you think Steve?

  15. ncbill says:

    Vehicle fuel cells (PEM fuel cells) are unfortunately burdened with the requirement that they can only use hydrogen.

    However, some types of stationary fuel cells can use common gaseous or liquid fuels directly, and are already being tested (e.g. the “Bloom Box”)

  16. daedalus2u says:

    I read some more about NH3BH3 and I am confident it will never be used to store H2 to power fuel cells for vehicles.

    NH3BH3 does have a very high hydrogen density. It is also unstable so that H2 can be released spontaneously via an exothermic reaction. That reaction gets fast (and self-accelerating) at ~120 C. There are two ways to get H2, decomposition and hydrolysis. Hydrolysis yields a bit more H2, but requires H2O and is more exothermic, meaning that there is more energy lost in the cycle of storing and liberating H2. The spontaneous liberation of H2 depends on the levels of impurities and the temperature.

    Neither of the two reactions are reversible, such that the material can be recycled via simply using H2, it requires more complicated chemistry with more energy losses. Boron is pretty toxic, and some of the boron-hydrogen intermediates in the regeneration of NH3BH3 are very toxic. Some of them are also pyrophoric. I think the combination of toxic, pyrophoric, unstable, requirement for offsite regeneration and high energy losses during regeneration will make this technology approach not feasible. It would require a large infrastructure to make, store, transport, deliver, recover the byproducts, return them to the central location to reprocess them.

    Electric vehicles with batteries are considerably more efficient than H2 vehicles due to the losses in H2 generation, storage and use in fuel cells.

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