Even when cryogenic (and hydrogen needs to be deeply cryogenic to remain liquid. 20K compared to liquid nitrogen's 77K) it is not particularly dense. It barel

Even when cryogenic (and hydrogen needs to be deeply cryogenic to remain liquid. 20K compared to liquid nitrogen's 77K) it is not particularly dense. It barely makes sense to use it in rockets since it has such poor density, causes embrittlement, and requires a great deal of insulation if you want to store it for any reasonable amount of time. If it is a chore to use the stuff for rocket science, I don't see it becoming a reasonable power source in more casual applications. If I am factually incorrect about anything here, I honestly do want to be told so.