See this link about energy density: http://www.aip.org/tip/INPHFA/vol-10/iss-1/p20.html http://www.aip.org/tip/INPHFA/vol-10/iss-1/p20.html Even liquid hydroge

See this link about energy density: http://www.aip.org/tip/INPHFA/vol-10/iss-1/p20.html http://www.aip.org/tip/INPHFA/vol-10/iss-1/p20.html Even liquid hydrogen doesn't come close to the volumetric energy density that seems like it'd be a solution for transportation. And the more compressed or cold you get it has a lot of attendant problems in terms of expansion effects of the gas, or the energy required to compress it. The permeability of hydrogen in containers, especially at high pressure, is also a real concern. Hydrogen escapes through container walls, and has bad (embrittling, usually) effects on them. A brittle 10,000psi H2 tank on board a car is something you really do not want. It seems to me the most feasible path to fuel cell power is to use non-pure-hydrogen fuels.