Forget the sun and wind — evaporating water could be the next big source of renewable energy, said James Temple at Technology Review. So-called evaporation-driven engines "generate power from the motion of bacterial spores that expand and contract as they absorb and release air moisture." Evaporation continues 24/7, so the engines, which sit on the water's surface, could provide power nonstop — unlike solar panels. (Courtesy image) The technology is still in a prototype phase, but a new study in the journal Nature Communications notes that the power available from natural evaporation in lakes and reservoirs in the continental U.S.