Closed Cycle Hydrogen Fuel Cell Question

[johndallman]

Originally Posted by Anaraxes

Used in a number of WW II fighter aircraft, for instance. But, as you say, not as fuel.

And several jet engines since then. The actual effect is that the heat which goes into turning the water into steam reduces the temperature of the air that makes up the working fluid of the engine. That allows greater thermodynamic efficiency, if you're willing to burn the necessary additional fuel.