I would not have thought the super-powers of evaporation would save us from ourselves, but here we are. From Nature Communications and Ahmet-Hamdi Cavusoglu, Xi Chen, Pierre Gentine & Ozgur Sahin:
Abstract
About 50% of the solar energy absorbed at the Earth’s surface drives evaporation, fueling the water cycle that affects various renewable energy resources, such as wind and hydropower. Recent advances demonstrate our nascent ability to convert evaporation energy into work, yet there is little understanding about the potential of this resource. Here we study the energy available from natural evaporation to predict the potential of this ubiquitous resource. We find that natural evaporation from open water surfaces could provide power densities comparable to current wind and solar technologies while cutting evaporative water losses by nearly half. We estimate up to 325 GW of power is potentially available in the United States. Strikingly, water’s large heat capacity is sufficient to control power output by storing excess energy when demand is low, thus reducing intermittency and improving reliability. Our findings motivate the improvement of materials and devices that convert energy from evaporation.
I think this is a calculation of potential. Consider this:
Recent advances in water responsive materials8,9,10,11 and devices12,13,14,15 demonstrate the ability to convert energy from evaporation into work. These materials perform work through a cycle of absorbing and rejecting water via evaporation. These water-responsive materials can be incorporated into evaporation-driven engines that harness energy when placed above a body of evaporating water (Fig. 1a–c). With improvements in energy conversion efficiency, such devices could become an avenue to harvest energy via natural evaporation from water reservoirs.
A quick glance through the paper did not reveal any consideration of negative consequences of actually harvesting this energy.
[EDIT 10/23/2017 fixed typo]
