Researchers have created a new kind of generator that uses bacterial spores to harness the untapped power of evaporating water . Scientists from Harvard and Columbia universities have created small, prototype generators by coating a sheet of rubber with a soilbacterium, Bacillus subtilis, that greatly expands and contracts with changes in humidity. Building a generator out of Legos, a miniature fan, a magnet, and the spore-covered sheet of latex, the researchers used the humidity-driven flexing of the rubber sheet to drive the movement of the magnet, which generated electricity. The developers of the potential renewable energy technology said that large electrical generators could one day be powered by changes in humidity from sun-warmed ponds and harbors. The scientists said that moistening and then drying a pound of the spores produces enough force to lift a car one meter. “If this technology is developed fully, it has a very promising endgame,” said Columbia University researcher Ozgur Sahin.