Little drops of energy

Green power is becoming more and more popular. Now one scientist thinks we could soon be generating energy from yet another natural phenomenon—one familiar to everyone.

  Photo Otsuka America Pharmaceutical

It was a milestone. In the past six months, for the first time, more electricity was generated in Germany from green sources than from coal. Renewable energy from wind, sun and biogas promises confidence. Another source could soon join their ranks. Ozgur Sahin, a biophysics professor at Columbia University, has an idea.

Sahin actually investigates the mechanical properties of bacteria, testing their strength and adhesion. When Sahin observed that some bacteria could absorb and repel water, he considered whether these properties could be useful. “When a stiff object changes its shape, it generates energy,” he explains. So he decided to utilize this law of nature. His result: the evaporation power plant.

The principle is quite simple. A rubber pad is coated with bac­terial spores, and if the air humidity is high, they absorb water and stretch the material. If the humidity drops, the bacteria release the water again, and the rubber pad curls back up. The movement is much like that of a muscle. “If you connect a turbine to it, such as the one behind the rotors of a wind turbine, the movement can be used to generate electricity,” Sahin says.

His idea is practical. Humidity can be used continuously—which doesn’t hold true for wind and sunlight. Sahin even finds the energy output persuasive: “Depending on the scale, the power plant could generate more energy per year than a wind turbine.” Furthermore, it could also store energy and ration it because, as Sahin explains, humidity can be captured. The material is ­cheap ­and environmentally friendly because the bacteria are recyclable. In places where evaporation strains water supplies, the power plant could have a twofold purpose: protect water supplies and produce energy.

Put into practice, the power plant could be installed above lakes or rivers. “You filter the evaporated water through the power plant and generate power before releasing it back into the atmosphere,” Sahin explains. The hitch: each of the facilities would be a massive encroachment on the landscape.

Sahin’s idea is only that at the moment, just an idea, and further research is necessary in order to actually test the power plant in a natural setting. The biggest hurdle is the material. As Sahin explains, “To generate a relevant amount of energy, a lot of bacteria would have to work together, to stretch and contract simultaneously.” It won’t be until he’s figured out a solution to this problem that his idea might one day have a long-lasting influence on the future of energy production.