From pp 378-9 of THORIUM: energy cheaper than coal...Hydrogen can power airplanes.
With extensive development, hydrogen may become a possible commercial airplane fuel. For the same amount of energy, hydrogen fuel has only 1/3 the weight of petroleum XE "petroleum" jet fuel, very advantageous to aircraft performance. Containing compressed hydrogen at 350 atmospheres of pressure (5000 psi) is possible with lightweight carbon-fiber tanks, but higher densities would require heavy steel tanks. At this pressure hydrogen’s energy density XE
"energy density" of 2.8 MJ/liter compares unfavorably to jet fuel at 33 MJ/liter, so the volume occupied by hydrogen tanks will be 12 times more than jet fuel tanks, reducing cargo or shortening flights.
Experimental Tupolev TU-155
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Russia demonstrated an airplane fueled by cryogenic, liquid hydrogen in 1989. Boeing XE "Boeing" used internal combustion engines on a hydrogen-fueled unmanned aircraft.