A recent study suggests that the solar energy that drives evaporation from lakes around the world could be captured, given suitable technologies, to perform useful work like generating electricity. The authors estimate that up to 325 gigawatts of power is potentially available in the United States, using natural evaporation from open water surfaces. The process could provide power densities “comparable to current wind and solar technologies,” they calculate.
Counterintuitively, while water used for cooling of thermal power plants competes with other water use in water-scare regions, the techniques suggested in this paper would provide an additional benefit by cutting evaporative water losses by nearly half.
How adding a suitable, yet to be developed technology to the surface of a lake could capture some of the energy lost to evaporation.
As an example, the authors consider converting the E.V. Spence Reservoir in Texas into an evaporation power plant. If the reservoir (38.0 km2 surface area in 2004) were completely covered by an evaporation-driven engine, it would generate an average annual power output of 178 MW. Moreover, the reservoir, which has been drastically impacted by a recent multi-year drought, could benefit from the potential water savings as a result of energy harvesting.
The authors note that respecting additional ecosystem concerns, such as maintaining oxygenation rates, could be expected to limit theoretical power generation potential, but the potential area available for open water energy harvesting is substantial—lakes and reservoirs cover at least square kilometres of the contiguous United States , not even counting the Great Lakes.
The study, “Potential for natural evaporation as a reliable renewable energy resource,” by Ahmet-Hamdi Cavusoglu, Xi Chen, Pierre Gentine and Ozgur Sahin, was published in Nature Communications.