A group of African students built a small generator where with
1 Liter of urine gives you 6 hours of electricity.
It's not 100% clear how much energy you can get out of that liter (you insensitive Imperial clod) though.
It's also not 100% clear whether the main aim of the setup is to purify water or to generate energy thanks to electrolysis.
In any case either aim would be a great thing in a continent like Africa. And the whole world as well.