rickn - That estimate must be skewed towards the end of that range because as of now there are NO Commercial aircraft using hydrogen, except spaceships.
The last Commercial Hydrogen Aircraft crashed in 1937.
Too bad it has NOTHING to do with PLUG. We had a plane they were working on, but I guess they ran out of funds. Also, something with Airbus that never amounted to anything more than a PR. With them ceasing production plants now not even a supply possibility.