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While electric vehicles have enjoyed a lot of recent attention, hydrogen fuel cell vehicles have somewhat fallen to the wayside. Sure, we can build FCVs. Honda has begun commercial production of its FCX Clarity, fuel cell busses are on the road, and there are even hydrogen filling stations being opened in California. But the general sense out there is that hydrogen will “always be ten years away”, as I once heard it put (by an EV advocate, it should be noted).
One reason some people feel this way has to do with the problem of hydrogen storage. Because hydrogen’s energy density is so low compared to gasoline, the equivalent of a tank of gas amounts to an enormous volume of hydrogen. Fuel cell vehicles today solve that problem by compressing the hydrogen gas into heavy metal tanks. These tanks, however, could use improvement. Much energy is lost simply compressing the gas, and some are concerned about the safety of a tank of highly pressurized, explosive gas .
For this reason, scientists are investigating alternative means of hydrogen storage. One chemist, Tom Autrey from Pacific Northwest National Laboratory, has been experimenting with a compound called ammonia borane (AB), which consists of hydrogen, nitrogen and boron – all relatively light elements. When AB is heated, it releases hydrogen gas for use in the fuel cell. When all the AB is “spent”, hydrogen gas can be pumped in to regenerate more.
The breakthrough for Autrey came when he discovered a more efficient way to synthesize AB – something that could make or break a technology’s ability to go to scale. He is also looking into ways to recycle solvents in order to make the entire production process economical (and clean).
Other researchers are trying to do similar things with ammonia and metal hydrides. This guy uses tiny spheres of titanium, which hydrogen adheres to. As long as the material is light, hydrogen dense and feasible to produce, it is a good candidate. And if we manage to come up with some decent hydrogen storage devices, hydrogen cars may eventually NOT be ten years away.
Via H2Daily
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written by Doug, September 25, 2008
The real problem is twofold: (1) massive energy losses (ratio of 4:1 or so) in creating the hydrogen, especially from electricity (the loss due to compression for storage is minor in comparison); and (2) lack of existing hydrogen-transportation infrastructure.
Infrastructure becomes less of an issue if you adopt the model of generating the H2 at each fillup point, drawing the energy from the electric grid. But that still leave the huge inefficiency -- an electric car charging at that station would ge 3x to 4x the miles from the same electricity going into the station vs. filling it with hydrogen.
But if battery technology hits a wall in the next 10 years or so, causing a relatively permanent need for hybrid vehicles (especially for large, long-haul motor-driven ones like semi trucks or ocean freighters), then hydrogen may have a role to play as the secondary fuel source, as its inefficiencies are nowhere near as bad as biofuels (well, cellulosic ethanol anyways; I don't know about biodiesel from algae)).
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written by Adam St. John, September 26, 2008
This also leads to discussion about efficiency and energy losses as Doug has mentioned.
Some storage methods perform well, but you have heat them to over 300 C. Some methods require cryogenic temperatures. Some methods require chemical reactions. Most are impractical, but serve as good starting points.
My main point is that there are and will continue to be many new "discoveries" in hydrogen storage materials, but rarely are the disadvantages pointed out in any general article.
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written by Uncle B, September 26, 2008
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written by Nick, October 01, 2008
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written by dalmuti509, October 02, 2008
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written by Gary Brown, October 28, 2008
Using that same locally generated solar electricity to charge the batteries in EV cars gets us four times as many cars filled up that week, for a total of eight, when what we need is a thousand. Local power generation just isn't going to get us anywhere, unfortunately. We have several desert areas in the country now going to waste however, which probably could use a little shade, and nary a snail-darter in sight.
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Oh, so it's easy to synthesize AB from its decomposition residue and hydrogen?
(Hint: no, it's impossible.)
The breakthrough for Autrey came when he discovered a more efficient way to synthesize AB
This is a clue that synthesis has been difficult, and thus confirms that the easy method of hydrogenating the residue gets you hydrogen and residue.
So if people were determined to have hydrogen cars, and determined that the hydrogen should come from onboard ammonia borane, they would ship the residue -- which ideally would be boron nitride, an innocuous powder sometimes used in cosmetics -- to power plants, and these power plants would ship back ammonia borane.
Ammonia borane is highly combustible. See my website for an alternate proposal involving boron, but no hydrogen.