Photos: Hydrogen hits the road

Honda says that its FCX, a car powered by hydrogen fuel cells, is the only such vehicle certified by the Environmental Protection Agency as meeting federal emissions standards. Here it is on display in Berkeley, Calif., in September as part of the California Fuel Cell Partnership's 2005 Road Rally.

Honda's fuel cell stack provides power to the compact car. It can operate at temperatures as low as 4 below zero and as high as 203 degrees.

Honda isn't the only automaker working at the low end of the periodic table. General Motors' Hydrogen 3, a compact minivan that seats five, operates on liquid and compressed hydrogen. It can store the hydrogen at up to 10,000 psi, at which pressure hydrogen is a liquid, and can power the vehicle for 250 miles.

Vehicles don't have to be compact to run on hydrogen. This bus, which is used in Perth, Western Australia, runs on fuel cells. (Its exhaust is steam.)

English company Intelligent Energy calls its ENV the world's first purpose-built fuel-cell motorcycle. The hydrogen-powered two-wheeler is said to hit speeds of 50 mph and run for four hours without refueling.