That amount of hydrogen will also make a nice boom / fire should it run into the ground or other immovable object.
Figure out a way to turn liquid hydrogen into something that is stabilized with something else - say ammonia (nh3) or methane (ch4) - that sounds like a practical and usable fuel, given that it is created via renewable electricity.
That's a caveat whether we're talking hydrogen, ammonia, methane, or some other of liquid energy.
The recent ground test of a hydrogen jet engine was done using much more expensive green hydrogen because they didn't need much of it and they wanted to make a point that it was "green". This is just to get their foot in the door so they can use fossil fuel derived hydrogen when push comes to a shove.
The technical problem of making green hydrogen safe to store is a small part of the problem compared to the economic barriers. When planes crash, the survival rate is already very low, the solution is to crash less. But how many people would still fly if a typical ticket on a plane using green hydrogen cost 10 times as much?
If using hydrogen in its pure liquid state, generating the hydrogen is just part of the equation, it still needs to be chilled to -423 F to liquify it and stored in insulated tanks to keep it from boiling. They need to be actively cooled for longer term storage because, as it boils, it must be allowed to escape to the atmosphere. Using hydrogen in its gaseous state requires extremely high pressures to store it, even then the volumetric energy density is very poor.
Using hydrogen attached to other compounds greatly reduces the gravimetric energy density of the fuel from while simultaneously increasing the cost beyond its already impractically high price.
The solution to green flying is the same as for green cars, it just needs to wait for a battery with a higher energy density, likely a solid-state battery. Because a practical battery will almost certainly precede that of cost-effective green hydrogen flight. In the interim, I would suggest a carbon tax on long-distance flights that would reduce the current situation created by cheap fossil fuel technology in which anyone with a middle-class or better income is able to fly around the globe on a whim on a regular basis. Perhaps the proceeds of the carbon tax could be invested in a combination of hydrogen research (in case we are over-looking a solution that is economically feasible) and solid-state battery development.
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