I remember reading an article a while ago about this being done in high-rise hotels. Could not find my original sources, but a quick google found this article:

I remember reading an article a while ago about this being done in high-rise hotels. Could not find my original sources, but a quick google found this article: http://bigthink.com/design-for-good/hydro-power-turning-toilet-wastewater-into-electricity http://bigthink.com/design-for-good/hydro-power-turning-toil...