Russell we still need fuel of some kind to keep aerospace airborne, after we quit fossil fuels.
Hydrogen meets this need, Rolls Royce at least have tested it with full on aero engines in flight on test planes, and it works.
Also all Ice vehicles are convertible to hydrogen, saving a lot of expensive future manufacturing of EVs.
There is a school that claims batteries will fly big commercial aircraft one day but it's impossible, unless they end up being reversible fuel cells which would be hydrogen powered anyhow. There is no other material that could comprise a battery with the energy content of hydrogen.
Metal embrittlement only happens significantly at very high pressure, beneath a threshold, It doesn't happen at all after liquefaction, but so far we only liquidise it at very low temperature. As said there appears a hole in hydrogen research around this - try and find any research at all that confirms liquefaction at room temperature was tried and failed. Even hydrogen reference text books malign it, claiming imperfect conversion processes generate "pollution", when we look to see what the pollution is, it's water. Since when was water ever pollution? it's been nobbled by the fossil fuels industry, who "funded" (defunded) nearly all research on it.
As said it comes into its own when generated from solar because then losses are no longer of consequence, given the energy is for free, because the heat of losses can never exceed the potential heat of the input solar energy, so whatever is produced, at whatever efficiency, is creation, reduction of the potential heating effect of the sun, reduction of entropy, which is the direct reverse of what happens when fossil fuels are consumed.
The point is that we have to do a lot of creation to reverse the damage done by consumption of fossil fuels, if we accept that the temperature rise is direct increase of entropy, which we should do, now we see the lie of a blanket effect in the adiabatic atmosphere, the lie is needed to do business for profit appearing to be fixing or addressing the problem, classic creation of bullshit business (Graeber - bullshit jobs, extended).
We should see what was lost in fossil fuels was stored energy, which was a kind of historical heatsink, it was all thrown to heat, the heat of increased entropy that we are measuring now. We need something to replace that heatsink, and hydrogen is there, so again it fills another need.
We need something to assure, filtrate, and circulate water supplies, hydrogen fills yet another need.
We need some kind of directly solar powered food of our own supply independent of the conventional food chain, to relieve a little of our load, and we see "Solein". We do a little research there and see the input energy component is hydrogen.
With all the other needs fulfilled by hydrogen, the deal is sealed, but this final one assuring the food supply of all humanity looks like a direct rubber stamp by God, if there could be such a thing, it's screaming at us to use it, we would be crazy not to see it, it has god signs all over it.
Hydrogen is a positive multiplier, ChatGPT 3.5 is showing how to use it to get massive power from the sun infinitely scaleable as money-fuel tree architecture which I describe in Medium.
I explain what energy multipliers are in this book:
https://www.amazon.com/Interview-Ai-Part-Multiplier-Framework-ebook/dp/B0CHGFKQVB