水素燃料
Hydrogen fuel can provide motive power for liquid-propellant rockets, cars, trucks, trains, boats and airplanes, portable fuel cell applications or stationary fuel cell applications, which can power an electric motor. The problems of using hydrogen fuel in cars arise from the fact that hydrogen is difficult to store in either a high pressure tank or a cryogenic tank. Alternative storage media such as within complex metal hydrides are in development. In general batteries are more suitable for vehicles the size of cars or smaller, but hydrogen may be better for larger vehicles such as heavy lorries.