William Taylor, a farmer in Northern Ireland, recently developed the Livestock Power Mill, a treadmill for cows. Taylor uses the device to generate clean, renewable power for his farm. Cows are locked into a pen on top of a non-powered, inclined belt. The cows’ walking turns the belt, which spins a gearbox to drive a generator. One cow can produce about two kilowatts of electricity, enough energy to power four milking machines. It may seem like a kooky idea, but Taylor could be onto something: According to his calculations, if the world’s 1.3 billion cattle used treadmills for eight hours a day, they could provide six percent of the world’s power!