Researchers at Columbia University found that U.S. lakes and reservoirs could potentially generate 325 gigawatts of power through evaporation as a renewable energy source, almost 70% of what the United States currently produces. Their findings were published in the journal Nature Communications.
While these experiments are still confined to the laboratories, evaporation-harvested power could potentially be made on demand, day or night, sunshine or cloudy, overcoming the irregularities of wind and solar power.
“We have the technology to harness energy from wind, water and the sun, but evaporation is just as powerful,” says the study’s senior author Ozgur Sahin, a biophysicist at Columbia. “We can now put a number on its potential.”
Sahin has previously demonstrated how the simple process of recycling water between land and air can be exploited to produce energy through the use of one machine developed in his lab, the “Evaporation Engine”. By controlling humidity with a shutter that opens and closes, prompting bacterial spores to expand and contract. The spores’ contractions are transferred to a generator that makes electricity.
Unlike solar and wind power that require batteries to supply power when the sun isn’t shining and wind isn’t blowing, evaporation-harvested power can be generated only when needed, on demand.
“Evaporation comes with a natural battery,” said study lead author, Ahmet-Hamdi Cavusoglu, a graduate student at Columbia. “You can make it your main source of power and draw on solar and wind when they’re available.”
Evaporation technology can also save water. In their study, researchers estimated that 25 trillion gallons a year, or about a fifth of the water Americans consume could potentially be saved during the energy-harvesting process.
States with growing populations and sunnier weather can best capitalize on evaporation’s capacity to generate power and reduce water waste, in part because evaporation packs more energy in warm and dry conditions.
“Evaporation has the potential to do a lot of work,” he said. “It’s nice to see that drying and wetting cycles can also be used to collect mechanical energy.”