Edit: I misunderstood context... My comment is regarding liquid hydrogen storage vessels. Gaseous can be stored indefinitely with proper seals. It doesn't leak

Edit: I misunderstood context... My comment is regarding liquid hydrogen storage vessels. Gaseous can be stored indefinitely with proper seals. It doesn't leak; it has to be vented. Hydrogen cannot be a liquid, no matter the pressure, at ambient temperatures, and there will always be heat leak. So your liquid hydrogen is always boiling, and with a good vacuum jacked dewar you'll lose 1-1.5% of the vessel's volume a day.