In real life, those are the hard parts. Given that you want high storage
pressures to get sizable amounts of gas into small tanks, the temptation
is to run the electrolysis cell at high pressure (since it's a lot cheaper
to push water in against a high pressure than to compress gas), and that
ups the ante on things like keeping the GOX and GH2 100% separate. (At
1atm, you can actually get away with generating and using mixed GOX/GH2;
this is done in some little welding systems aimed at jewelers and such --
Google "Brown's gas" for details. At high pressure, that's suicidally
dangerous.)
