At Maker Faire Africa 2012 in Lagos, Nigeria, four teenage girls showed a generator that ran on hydrogen extracted from urine. Urine goes into an electrolytic cell that separates out hydrogen, which is filtered, dried with liquid borax and fed to the generator. One-way valves guard against the explosion risk of hydrogen. They said one litre gave six hours of electricity.
Chemical engineer Gerardine Botte notes that extracting hydrogen from urine takes more energy than it returns. However, electrolysis of urea can make wastewater treatment more efficient while producing hydrogen as a by-product.
via Teens Create A Way To Use Urine As Fuel | Forbes (archived)