Evaporation engine, a theoretical machine that aims to convert evaporation energy into electricity, takes advantage of the infinite expanse of evaporating water from sun-heated lakes and dams. “Evaporation has the potential to be greater than wind power and closer to solar power,” said Ozgur Sahin, a researcher from the University of Columbia.
The prototypes of the evaporation engine use materials that shrink when they get dried. Such is a fabricated tape covered with bacterial spores, which curl up as they dry. As a consequence, the tape shrinks. “They work like a muscle. They can push and pull with a lot of force,” explained Sahin.
The evaporation engine, when installed just above warm water, will make use of the changes in ambient humidity. In this way, the engine doesn’t have to get soaked in water repeatedly that will result in dirt accumulation and chemical contamination.
How the changes in humidity control the engine? When the machine’s shutters are closed, the tapes are exposed to high humidity, making the tapes stretch. When the tapes are stretched, the shutters will open, exposing the tapes to heat and allow them to dry up and thus, shrink.
Although there is less evaporation occurring at night, the evaporation engine is still expected to function. According to Sahin, water evaporation in US lakes and dams could provide up to 2.85 million megawatt hours of electricity annually, which is equivalent to two-thirds of electricity generated in US last 2015. The engine can be also installed in irrigated fields, greenhouses, and sheltered bays. Moreover, since the evaporation engine is to be made up of biological materials, it is projected to be much cheaper and easier to dispose of than solar cells.
The biggest challenge this new technology faces is the efficient conversion of evaporation energy into electrical energy. “The question is whether there is any practical way to capture that energy,” asserted Ken Caldeira of the Carnegie Institution for Science in Stanford, California. He has expressed his doubts about the mere possibility of efficient conversion of the evaporation energy.
[via New Scientist]