Anything that moves in nature has power behind it. This includes wind, waves and even evaporating water. Recently, researchers at Columbia university set out to find ways to harness the power of evaporating water and put that power to work.
In a report published online in Nature Communications, the researchers demonstrated two different methods of generating power using bacteria and evaporation. At the moment these methods are generating only small amounts of power, enough to power a small electric light and a toy car.
The researchers think, however, that these methods can be scaled up to generate much larger amounts of power. Eventually floating power generators could be located on resevoirs or bays producing electricity for cities and towns.
“Evaporation is a fundamental force of nature. It’s everywhere, and it’s more powerful than other forces like wind and waves,” said Ozgur Sahin, Ph.D., in a statement.
Sahin is an associate professor of biological sciences and physics at Columbia University and the paper’s lead author.
Both approaches to evaporation-power involved using double sized plastic tape, similar to the tape used in audio cassettes. Spores, which expand in high humidity and shrink when dry were placed in patterns onto the tape. The tape was then placed into a plastic case with shutters to control the influx of water vapor.
As the bacteria absorbed or released water it pulled on the tape, which in turn pulled on whatever it was attached to, generating power.
“When we placed water beneath the device, it suddenly came to life, moving on its own,” said Xi Chen, a postdoctoral fellow in Sahin’s lab.
In one case the tape powered pistons which, in turn powered a small light. Even given its current, small, power output the team believes that it could be used to power floating lights or sensors on the ocean floor.
In the other case, the tape was used to power a wheel which drove a small toy car. According to Sahin, in the future the “Moisture Mill” could be used in the design of a full size engine which wouldn’t require an engine or a battery. An even larger version could be used to generate as much power as a wind turbine.
While the technology is still in its infancy, it could eventually make a nice addition to the mix of renewable energies. The ability to store the tape in its moist condition until the energy is needed it is relatively easy to envision “evaporation batteries”, charged on warm days and stored until they are needed.
