In Brief
Energy harvested from the evaporation process could provide the bulk of the United States' power requirements, according to a new study. What's more, it could simultaneously help regions affected by droughts retain water held in lakes and reservoirs.

Water Works

Researchers investigating the potential for evaporation to be used as a source of renewable energy have found that the United States’ reservoirs and lakes could produce 325 gigawatts of power. That’s equivalent to almost 70 percent of the energy that the country currently generates.

“We have the technology to harness energy from wind, water, and the Sun, but evaporation is just as powerful,” senior author Ozgur Sahin, a biophysicist at Columbia University, stated in a press release. “We can now put a number on its potential.”

Sahin has previously demonstrated the process he’s proposing using a device dubbed the Evaporation Engine. This machine controls humidity using a shutter than opens and closes, prompting bacterial spores to expand and contract. That motion is then transferred to a generator, which produces electricity.

With this methodology in place, the researchers set out to see how much of the country’s energy needs could be met by evaporation. They determined that it has the potential to be a primary source of renewable energy, with solar and wind contributing as secondary sources when available and necessary.

Dry Spell

Power harvested from evaporation is still being tested for feasibility, but many are hopeful it could provide another avenue for renewable energy. It has a distinct advantage over solar and wind power because, in theory, it can be produced on-demand with no restrictions related to weather or the position of the Sun.

Aside from providing clean energy, harnessing evaporation in this way could also help regions affected by drought. As much as half of the water that evaporates into the atmosphere could be saved while the harvesting process is taking place.

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The researchers hypothesize that this could amount to 25 trillion gallons of water a year. Essentially, drier regions that already maintain reservoirs to hold water in case of a drought could benefit twice, retaining more of that supply while producing energy at the same time.

Another advantage of this method is the fact that, unlike solar or wind energy, it doesn’t require battery storage. Batteries are expensive, and in the case of solar, producing models with sufficient capacity is a limiting factor now that panels are cheaper and more efficient than ever before.

Now that evaporation’s potential is known, the researchers behind the Evaporation Engine are working on ways to make their spore-studded materials more efficient. Moving forward, they hope to test their process on a lake, reservoir, or greenhouse to further test evaporation’s ability to produce clean energy.