<P> Autostudi S.r.l's H - Due is a hydrogen - powered quad, capable of transporting 1 - 3 passengers . A concept for a hydrogen - powered tractor has been proposed . </P> <P> Companies such as Boeing, Lange Aviation, and the German Aerospace Center pursue hydrogen as fuel for manned and unmanned airplanes . In February 2008 Boeing tested a manned flight of a small aircraft powered by a hydrogen fuel cell . Unmanned hydrogen planes have also been tested . For large passenger airplanes, The Times reported that "Boeing said that hydrogen fuel cells were unlikely to power the engines of large passenger jet airplanes but could be used as backup or auxiliary power units onboard ." </P> <P> In July 2010 Boeing unveiled its hydrogen - powered Phantom Eye UAV, powered by two Ford internal - combustion engines that have been converted to run on hydrogen . </P> <P> In Britain, the Reaction Engines A2 has been proposed to use the thermodynamic properties of liquid hydrogen to achieve very high speed, long distance (antipodal) flight by burning it in a precooled jet engine . </P>

How much is hydrogen fuel for a car