Originally Posted by
Winemaker
Again, this requires large amounts of electricity - at least the same amount as that produced by the fuel cell when it recombines the hydrogen with oxygen to produce water.
Electrolysis has an efficiency of about 70%, fuel cells about 60%. Overall that is just under 50%, not taking into account losses due to compression, liquifaction and heating and/or cooling (which is an issue with fuel cells).
I feel that especially due to logistical challenges liquid hydrogen is practically unusable for anything else than rocket propulsion. And even for that it is not exaclty ideal.