Researchers at Columbia University have recently created a unique engine that is powered by evaporation. Evaporation unlike other types of renewable energy is constantly occurring, and the device created at Columbia contains bacterial spores, Bacillus subtilis, that respond to even the slightest changes in humidity. The spores expand when they absorb water and contract as they begin to dry out; the device uses the energy created by the contractions and expansions of the spores to power rotary or piston engines. Scientists can then control the amount of moisture in the air to help regulate the rate at which and the amount of water that the spores are absorbing or releasing.
Currently the size of the engines are too small to produce a practical amount of electricity (a water surface of 8×8 cm produces about two microwatts of electricity). However the creation of the device is what’s promising as Ozgur Sahin, the lead researcher, has said that it is possible to make the engines 100 times more powerful with adjustments to the engine. One method is to increase the size of the spores or adjusting the placement of the devices. Sahin suggested putting the devices on the surface of a body of water to have a consistent source of water for renewable energy but conceded that they are years away from being able to do so. While impractical at the moment, the device can eventually help revolutionize the field of natural energy.