Detander - a gas liquifier - can be pretty small and lightweight even for a big flow. Industrial hydrogen liquifiers are built routinely since 1950s if not earl

Detander - a gas liquifier - can be pretty small and lightweight even for a big flow. Industrial hydrogen liquifiers are built routinely since 1950s if not earlier. If you're trying to liquify hydrogen, you'll find out that most - almost all - impurities in the gas become liquid or solid before hydrogen becomes liquid. That's a good way to clean hydrogen, so you won't have an odd mixture as the result.