Floating Solar: Win-Win for Drought-Stricken US Lakes

Worried about our languishing Southwestern dams and reservoirs? Floating solar arrays, or "floatovoltaics," can help in two ways, generating major new increments of clean power while reducing surface evaporation on drought-stricken water bodies like Lake Mead and Lake Powell, on the Colorado River.

In an article I just wrote for Yale Environment 360, I survey the emergence of floating solar arrays in places as diverse as a sewage treatment plant in South Australia, a hydroelectric dam complex in the Brazilian Amazon, and drinking water reservoirs in India, Japan, and the UK. My primary focus, though, is on a floating solar frontier that has yet to be reached: the shrinking reservoirs that feed two of America's largest hydro dams, the Glen Canyon Dam on Lake Powell and the Hoover Dam on Lake Mead. By covering just 6 percent of Lake Mead with floating solar panels, I argue that the benefits would be twofold: significantly greater power-generating capacity than the Hoover Dam offers today and as much as a 90 percent reduction in surface-water evaporation on that portion of the lake.

Is this a panacea for the diminishing water supplies sourced by the Colorado River? No, but it could be one piece of a multi-faceted strategy for bringing the Southwest's water supply and demand into a more sustained balance. In addition, at a time when we urgently need to curb US greenhouse gas emissions, opening up our waters to solar development can help us make the shift toward an economy based on clean, renewable energy instead of polluting fossil fuels.