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.<p>If you&#x27;re trying to liquify hydrogen, you&#x27;ll find out that most - almost all - impurities in the gas become liquid or solid before hydrogen becomes liquid. That&#x27;s a good way to clean hydrogen, so you won&#x27;t have an odd mixture as the result.