Tom Broadbent, a student at De Montfort University in Leicester, UK, built a machine that harvests the kinetic energy of water that is flushed down a toilet. It's called HighDro Power and can save about £926 in a seven-storey building:
He added: “HighDro Power works by using the water discharged from appliances such as showers, toilets and sinks in high-rise apartments. The water goes down the pipe and hits four turbine blades that drive one generator.
“The whole thing was influenced by traditional waterwheels to ensure that any solids passing through had limited effects on whether they could function.”
Link via Popular Science | Photo: Creative Boom