A 2011 study by the National Renewable Energy Laboratory concluded that hydroelectric plants in the United States consumed between of electricity generated, through evaporation losses in the reservoir. The median loss was , which is higher than the loss for generation technologies that use cooling towers, including concentrating solar power at for CSP trough and for CSP tower, coal at , nuclear at , and natural gas at . Where there are multiple uses of reservoirs such as water supply, recreation, and flood control, all reservoir evaporation is attributed to power production.