Evaporation to Produce Electricity



Man’s hunt for producing power for his rising needs is no wrong in any sense, as it is the need of the hour.  But many power generating sources (electricity) also produce greenhouse gas emissions. Hence, to overcome this sort of side-effect, the search is on for producing uninterrupted supply of clean energy.

Researchers in U.S. have found a way to harness evaporation of water to produce enough power to light up a small LED bulb and run a tiny car.

Lead researcher Ozgur Sahin from Columbia University said that “evaporation is a fundamental force of nature that is happening everywhere and is more powerful than wind and waves”.  He discovered that bacteria spores shrink and swell as a result of changing humidity and can push and pull other objects with surprising force.

Sahin and his team stuck Bacillus subtilis spores onto thin strips of tape, similar to cassette tape.  The tape shrunk or swelled depending on dryness and humidity of the air around. “Several of these strips together can contact with enough force to lift small weights of 0.2 lbs to 0.7 lbs [0.09 to 0.3 kg] – 50 times the weight of the strips themselves”, writes Kiona Smith-Strickland for Discover magazine.

The strips are named hygroscopy driven artificial muscles or HYDRAs.  A shuttered structure that floats on water will use these tapes to open up shutters when the tapes expand due to humidity. The opened shutters dry up the device and so the shrinking tape closes the shutters causing the open-shut cycle to repeat endlessly. When the opening and shutting action is used as a rudimentary piston and linked to a generator, enough electricity is produced to cause a small LED light to flash on and off.

Evaporation from a pool of water is converted to electric power.  With improved versions, if the technology can be scaled up, giant generators floating above  lakes, dams and rivers will silently generate clean energy.

A plastic wheel with the spore-covered tape was placed in such a way that half of it was exposed to a dry environment and the other half to a humid environment, the wheel turned producing enough force  to make a small toy car weighing 0.1 kg roll forward on its own.  If this can be scaled up, evaporation mills will provide renewable energy in abundance.