Evaporation Engine Harvests Energy From Water Vapour At Room Temperature

Bioengineers at the Columbia University have succeeded in harvesting energy from water evaporating at room temperature. The team led by Ozgur Sahin has developed a tiny, $5 evaporation engine that can drive a small buggy or power an LED. The engine practically uses nothing but water as the fuel and room temperature to function. Following is the photo of the functional engine that measures just about 4" on each side. 

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This tiny engine is indeed a breakthrough innovation. The engine has been designed and developed to harvest the energy from natural phenomenon that was mostly ignored so far. The functioning of the engine is even more interesting. Sahin's team employed hygroscopy-driven artificial muscles aka HYDRAs to power the engine. The HYDRAs are very tiny plastic strips that expand and contract based on the humidity in the air. A small band of HYDRA can have about a million+ expansion/contraction cycles without noticeable degradation of the material.

Sahin has been working on employing this expansion and contraction of HYDRAs for over a decade. Using advanced imaging techniques, he studied the characteristics of grass bacillus bacteria with respect to humidity in the surroundings. After lot of experiments, Sahin figured out a way to duplicate the spore's responses. He succeeded in getting the HYDRAs to expand and contract in one direction with response to moisture. 

As you'd notice in the video above, the engine rests over a puddle of water at room temperature. As water evaporates, the humidity inside the HYDRAs chamber increases, causing the HYDRAs to expand. This expansion triggers a small electromagnetic generator. The expanding HYDRAs also open a flap at the top so that the humidity inside the chamber drops - causing the HYDRAs to shrink; and the cycle repeats. 

The warmer the water, the faster is the engine. Sahin found out that water at 60 degrees allow the flaps to open and close once every 40 seconds and about once every ten seconds at 90 degrees. Sahin and his team also developed a small turbine-style buggy powered by evaporating water. Check it out in the video below -

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