My plan was to compress the H2 into a propane tank at perhaps 100 PSI. Stove burners that are set-up with the proper air-mixing ratio for natural gas will work just fine with H2 (I'm told).

I think on-demand generation as an engine fuel supplement would work best with a constant RPM diesel generator with a governor. As gas supply varies, the amount of diesel fuel that is injected will be automatically throttled. An alternator from some 18-wheelers will have two pulley grooves. By adapting it into the stock location, the original engines alternator can be bracketed to accept a second belt (run by the first alt). This way the stock alternator and voltage regulator will function normally and the other alternator is free to supply the hydroxy cell.

The plastic tub (squarish?) should have 6 plastic dividers glued in to make seven thin cells with a couple small weep-holes near the bottom so the water levels stay the same.

Each cell should have two stainless steel plates (square inches depend on how many amps you wish to pump, bigger=more gas) If the plates are connected in series and fed 14 volts, then each plate-set will see about 2 volts. A plate-set will try to flow the voltage from the edges, so the edges should be covered with plastic, forcing the voltage to pass across the plate faces.

The plate sides that face each other should be rough-sanded (it helps, I don't know why). Since the plates should be kept as parallel as possible, and kept 1/8" apart, and edged in plastic, you might take finger-thick strips of plastic and cut two parallel slots on one side (1/8" apart) perhaps with a hacksaw blade, then 4 of these would make a "frame" for one plate-set.

The top of the tub will be the gas outlet, it should feed a "bubbler" similar to a radiator overflow catch-can. It is a container of convenient size with two openings on top. One outlet has a tube connecting the top of the tub to a tube stub that extends down to the bottom of the can (half-filled with water). The other outlet has a tube connected to the intake manifold.

This bubbler will act as a check valve and will also stabilize the moisture in the gas. When the engine is running, there will be a partial vacuum on top of the can water. Then, when the tub produces any gas, it will flow to the bottom of the water can, and "bubble up".

As the electrolyte water gasses away, you have to add distilled water (tap water has an inconsistent mineral content). One way is to have yet another container alongside the tub (the two water levels will stay equal). Make a float valve similar to what's in the back of a toilet tank. Connect the two bottoms with a tube and a check valve so the water can only flow one way.

An elevated distilled water store feeds the float valve, which keeps the "leveling container" at a water level above the plate tops in the tub.