- Just an idea - Here's the idea: If you use a staged liquid anaerobic/aerobic waste-water treatment system, one bi-product is Hydrogen Sulfide gas. The geysers at Yellowstone have a sort of bacteria that feed on sulfurous compounds in the water. If you bubbled air, and separately, the Hydrogen Sulfide gas up through some watery environment otherwise engineered for those bacteria, becoming partially dilute, soluble, or saturated in that watery mix, maybe the bacteria would be able to feed partially on that soluble sulfur, also having whatever else they need (air/oxygen and food) reducing its content, and a slightly purer hydrogen gas might result. Maybe This, together with oxygen could be fed through a crude Hydrogen Fuel Cell ? In this way, a waste-water treatment process could also provide electricity. - ?
It could also be a part of a dual system - (see also my other Hydrogen Sufide/Fryolator froth fuel topic)
Well somethings only a byproduct if its not put to good use is it?
The only two things that come to mind after giving this idea a few days thought is the very low amount of Hydrogen sulfide gas that will be given off by the anaerobic bacteria. If I'm not mistaken in a digester with a healthy bacteria population your gas should be 50% to 70% methane 30 to 50% carbon dioxide and less then 5% Hydrogen and Hydrogen sulfide displacing the 2 major gasses. In a very happy digester the hydrogen sulfide and hydrogen component is negligible. But i can see less then optimal conditions with a waste water treatment system. So that brings me to my first question. How do you plan to separate the hydrogen sulfide from the carbon dioxide and methane majority of the gas?
The other thing i was thinking. Well not so much a question but something i should point out. Any fuel cell that can be bought off the shelf is very quickly damaged by sulfur compounds. That's why fuel processors to prep fossil fuels for a hydrogen fuel cell cost as much as the fuel cell its self. And don't have a spectacular life span because of the sulfur compounds attack them as well. So you would need a fool proof plan to keep any lose hydrogen sulfide out of the fuel cell. Perhaps filtering lose hydrogen sulfide threw some KOH or better yet NaOH.
Do you have any advanced plans for the methane gas you would be getting from the digester? If not then i would use the methane gas its self to run the fuel cell after running threw a fuel processor to reduce it to hydrogen. And how i would do that is by first cooling the gas from the digester to help condense water vapor in the gas. Then use a off the shelf compressed air water trap to catch the condensate. Then i would filter it with KOH or the cheaper NaOH. The NaOH should take out all the remaining water vapor, Co2 and H2S in the gas. At that point you should have gas that's identical to natural gas they pipe into your home, if you live in north America. Granted that is not running on the hydrogen sulfide but it is using ideas that are already well known and using parts that can be had off shelf.