They would be great for RVs. Electricity, charging batts, and fresh water as a byproduct. (No cryo stirs though, please)
Hydrogen is tough stuff to keep contained. Notorious for leaks. I think it also has to be kept at cryogenic temperatures as well.
I thought peeps were working on Propane, CH4, gasoline and JetFuel/Diesel fuel cells.
I’ve heard the H2 molecules are very, very small.