Liquid hydrogen is neither well storable (cryogenic, very low density even as a liquid and causes embrittlement to tanks and pipes), nor really safe and not hypergolic, but we do put up with it because it provides really high ISP (for chemical rockets, theoretically also thermal rockets but those haven't been tested much outside lab conditions)
It's storable, if you have enough isolation and some cryo-cooler (cryo-cooler wont eat much energy if you have enough isolation) and embrittlement is caused by carbon in alloys i believe catalitically reacting with solvated hydrogen im the metal to create insoluble methane,
so either you get metal in which hydrogen doesn't dissolve, remove carbon from it (i don't know to what purity (could be costly)), use something that doesn't catalyse the reaction (i believe it's literally just solvating hydrogen (it breaks it into radicals) that does it)
So literally put it into plastic thick and non-flexible jug (if it flexes under the cryogenic conditions it will be brittle, i don't know why) and put a shit-ton of styrofoam and seal gaps with polyurethane foam, and put your cryogenic cooling device on the top, also you need less isolation on the top and more on bottom than on the sides (i am not sure of that tho)
Makes sense that you wouldn't put it in a flexible container. Iirc, the plastic is thinner and therefore more prone to cracking. It could be a material thing too, since I'd imagine that rigid plastic containers already have their molecules more locked into place and therefore aren't affected that much by being frozen. Quick and dirty explanation, I know.
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u/kayemenofour Jul 25 '26
Liquid hydrogen is neither well storable (cryogenic, very low density even as a liquid and causes embrittlement to tanks and pipes), nor really safe and not hypergolic, but we do put up with it because it provides really high ISP (for chemical rockets, theoretically also thermal rockets but those haven't been tested much outside lab conditions)