Without trying to hijack the thread....good info DM! The idea of using rebar and sodium carbonate is cheap and available materials. I'm not a chemist, nor do I play one on TV. I do know cracking hydrogen from water is an art.....I do know enough I caution people when using electrolysis.
Good lock with your work. My first job out of college was as the head chemist and engineer at an aircraft parts plating operation. Nasty stuff. Oh, I mentioned using an industrial detergent. If you do so, make sure that it does not foam. Foam will trap both hydrogen and oxgen and makes for a big, big boom.