First off, please forgive me, I am a chemistry novice!
- Fuel for the system is distilled water
- Split water into Hydrogen and Oxygen (electrolysis or similar process)
- Exhaust Oxygen
- Burn Hydrogen to power a generator/engine
- Generator/engine charges battery
- Battery powers Step 2 as well as whatever else we want to power
- Energy gained needs to be greater than the sum of lost energy in all steps, as well as the energy required to perform electrolysis
- We could compress the exhaust oxygen and use that as an energy source?
- Is there a danger of running out of hydrogen? (Forgive my naivety, but I've heard about a helium shortage...)