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.
written by G.R.L. Cowan, September 25, 2008
written by Adam St. John, September 26, 2008
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