Bill Gates thinks the modern-day flush toilet isn’t good enough. Most of the developing world can’t afford to use it, and poor sanitation spreads diarrheal diseases.

So the Gates Foundation is challenging universities to build a better toilet—latrines that are hygienic, generate energy and don’t require running water or a septic system. The foundation is giving $41.5 million toward that end, and proposals include toilets powered by solar panels, heat, or microwave.

Supposedly the microwave method works pretty well but the spinning makes everybody sick.