A hydrogen vehicle is a vehicle that uses hydrogen as its onboard fuel for motive power. Hydrogen vehicles include hydrogen fueled space rockets, as well as automobiles and other transportation vehicles. The power plants of such vehicles convert the chemical energy of hydrogen to mechanical energy either by burning hydrogen in an internal combustion engine, or by reacting hydrogen with oxygen in a fuel cell to run electric motors. Widespread use of hydrogen for fueling transportation is a key element of a proposed hydrogen economy.
Hydrogen fuel does not occur naturally on Earth and thus is not an energy source; rather it is an energy carrier. As of 2014, 95% of hydrogen is made from methane. It can be produced using renewable sources, but that is an expensive process. Integrated wind-to-hydrogen (power to gas) plants, using electrolysis of water, are being explored.
Many companies are working to develop technologies that might efficiently exploit the potential of hydrogen energy for use in motor vehicles. As of November 2013 there are demonstration fleets of hydrogen fuel cell vehicles undergoing field testing including the Chevrolet Equinox Fuel Cell, Honda FCX Clarity, Hyundai ix35 FCEV and Mercedes-Benz B-Class F-Cell. The drawbacks of hydrogen use are high carbon emissions intensity when produced from natural gas, capital cost burden, low energy content per unit volume, low performance of fuel cell vehicles compared with gasoline vehicles, production and compression of hydrogen, and the large investment in infrastructure that would be required to fuel vehicles.
Vehicles which have been demonstrated to run on hydrogen are buses, trams, bicycles, motorcycles and scooters, quads and tractors, airplanes, fork trucks and rockets.
Hydrogen fuel cells are relatively expensive to produce, as their designs require rare substances such as platinum as a catalyst. By 2010, the cost had fallen 80% and that automobile fuel cells might be manufactured for $51/kW, assuming high-volume manufacturing cost savings. The service life of fuel cells is comparable to that of other vehicles. PEM service life is 7,300 hours under cycling conditions.
