Michael Hoffmann's solar-powered toilet meets all requirements to make it usable in the Third World. It needs no running water, electricity or septic system. It doesn't discharge pollutants and costs just pennies to operate.
The toilet's electrochemical reactor breaks down water and human waste into fertilizer and hydrogen, which can be stored in hydrogen fuel cells as energy. The treated water can then be reused to flush the toilet or for irrigation. Hoffmann's team was awarded $100,000 for their design.
"The current design has a real problem. It uses a lot of water, requires a very expensive system to bring in very clean water, then you make that water dirty. You have a very expensive system to take it away," said Bill Gates.
Caltech's proposal was one of eight that had received grant money last summer from the Gates Foundation. The team built a prototype, and after a year of designing and testing, they showed off their creation.
Loughborough University in the United Kingdom won the $60,000 second-place prize for its toilet design, which produces biological charcoal, minerals and clean water.
Scientists say proper sanitation could prevent many deaths around the world and the spread of deadly diseases.