Asking as someone only remotely familiar with hydrogen as a fuel: Don't you have the problem of tanks and pipes becoming brittle from hydrogen diffusing into the material? Are there existing/upcoming solutions for this? I was under the impression that this is a pretty fundamental problem with hydrogen being just a proton essentially..
Aluminum is supposed to be pretty tolerant of extra protons in its matrix. You might passivate the surface to be electropositive, to repel the ends of the H2 molecules as they try to weasel into the gaps. Liquified hydrogen is anyway much less mobile than gaseous hydrogen, and when used at atmospheric pressure, nothing is trying to force the molecules in.
Gaseous H2 at the extreme pressure people try to use is a much greater nuisance.
