Boeing's hydrogen-powered plane

Boeing has flown the first manned aircraft powered by a hydrogen fuel cell. It wasn't exactly an airliner, weighing only 800 kg and flying at 100 kph with just the pilot aboard, and indeed Boeing doesn't see a future for the cells in powering large aircraft. The aerospace giant does suggest, however, that "greener" and quieter general aviation fleets may result from further development of this approach. (Their press release didn't mention UAVs, but there's an obvious potential there, especially for military and police users who would appreciate having silent UAVs.)