BMW H-Bomb: Extreme Alternative Fuel

The process involves generating hydrogen from water onboard the vehicle, which removes the need to store hydrogen in a tank. Fuel-tank design is one of the main challenges facing hydrogen car designers, and at present involves serious difficulties. The insulated cryogenic tank in BMW's Hydrogen Seven demonstrator car, as an example, will lose its entire contents to boil-off in matter of days. This doesn't just strand the vehicle (or compel its driver to use the backup petrol tank): it also means that a fuelled-up Hydrogen Seven can't be parked in an enclosed space, lest a dangerous buildup of explosive gas develop.

But boffins led by Professor Jerry Woodall of Purdue University reckon they've managed to sidestep this snag. In their process, water is combined with an alloy of aluminium and gallium. The aluminium oxidises, releasing gaseous hydrogen which could then be used to fuel a conventional car engine as in the Hydrogen Seven. The role of the gallium additive is to prevent a skin of oxide forming on the surface of the aluminium and allow all the metal to be used.

Woodall came across the reaction by accident in the course of research into semiconductors.

"I was cleaning a crucible containing liquid alloys of gallium and aluminum," he says. "When I added water to this alloy - talk about a discovery - there was a violent poof."