Electricity generated from water evaporating from lakes could be the next step in renewable power.
Lakes and reservoirs in the USA could generate 325 gigawatts of power, nearly 70% of what the United States currently produces, according to figures from Columbia University.
Unlike wind and solar power, energy from evaporated water can be gathered at any time of day – regardless of how sunny or windy it is. Of course, in sunnier places there is likely to be more evaporation so the authors say drought-prone states like California, Nevada and Arizona may have the most potential for this green technology.
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“We have the technology to harness energy from wind, water and the sun, but evaporation is just as powerful,” said the study’s lead author Ozgur Sahin, a biophysicist at Columbia. “We can now put a number on its potential.”
The authors estimate up to 325 gigawatts of power is potentially available from evaporation from existing lakes and reservoirs larger than 0.1 km2.
The experiment is contained to a lab for now but it works using a shutter that opens and closes. Inside, spores contract and expand as they are exposed to changes in the humidity or the air. The contractions of these bacterial spores are hooked up to a generator, which creates electricity.
“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.”
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“It has the potential to do a lot of work,” said Klaus Lackner, a physicist at Arizona State University who was not involved in the study. “It’s nice to see that drying and wetting cycles can also be used to collect mechanical energy.”
Not only does the system generate clean electricity, but it might also save water. In the study, researchers estimate half of the water evaporating naturally from lakes and reservoirs into the atmosphere could be saved during the energy-harvesting process.
They said this comes 25 trillion gallons a year, or about a fifth of the water consumed in the USA.
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