You’ve heard of steam power—now, there’s evaporation power.
A team of scientists at Columbia University have figured out a way to generate electricity from harnessing the forces generated by water evaporation, not heated water, but water at room temperature.
In a steam engine, the mechanical energy from the rise of the heated water is transformed into electricity by a electromagnetic generator. An evaporation engine also harnesses electricity from mechanical energy, but it’s not from the upward pressure of the vapors, but the contractions of bacteria.
The engines are called HYDRAs, or hygroscopy-driven artificial muscles, and they work by harvesting the lengthening and contraction that grass bacillus spores experience when exposed to different levels of humidity.
“Changing size this much is highly unusual for a material that is as rigid as wood or plastic,” said Ozgur Sahin, the lead engineer on the team. “We figured that expanding and contracting spores can act like a muscle, pushing and pulling other objects. We noticed that we could harness the motion of spores and convert it to electrical energy.”
The spores are placed on pieces of plastic strips, which expand and contract, pulling on a cord that transforms that mechanical energy into electricity. Spores can expand by up to 40 percent in length when exposed to moisture.
The energy that the evaporation engines produce isn’t very much, with prototypes churning out power in 60 micro-watt bursts. However, to put that in perspective, that’s evaporation from a thin 3 x 4 inch sheet of water, and it’s enough to power LED lights.
“The subtle phenomenon of evaporation has big potential. This may be an opening for a completely new energy platform,” says Sahin.
