Harnessing the Power of Humidity Whenever water evaporates, it takes energy with it. A team of researchers has found a way to tap into this energy, using humidity-sensitive bacteria. Their method could lead to large-scale generators that create abundant energy from moisture in the air above sun-warmed ponds and harbors. The researchers coated a latex rubber sheet with a strain of bacteria called Bacillus subtilis, which shrivel into hard spores when their surroundings run dry and swell back up to their original sizes when moisture returns. The bacteria’s expansions and contractions added to the rubber’s own expansions and contractions as the surrounding air grew alternately drier or more humid, and this propelled an adjacent magnet to power an actuator and generate electricity. Evaporation is the largest power source in nature, says lead researcher Ozgur Sahin, associate professor of biological sciences and physics at Columbia University. Even tiny bacteria are powerful when they wield it. In his first experiments, Sahin placed spores on a silicon plank. As soon as he breathed near it, the plank began bending back and forth with a thousand times as much force as a human muscle and 10 times as much force as many industrial-grade materials. By his calculations, moistening a pound of dry spores would create enough thrust to lift a car off the ground. Even more force generation might be possible with genetically engineered bacteria, he adds. nature/nnano/journal/v9/n2/full/nnano.2013.290.html
Posted on: Thu, 06 Mar 2014 11:51:01 +0000