nce on coal-fired power plants that emit climate-changing greenhouse gases.In all, undeveloped rivers and streams in the U.S. have 84.7 GW (gigawatts) of hydropower capacity, enough to generate 460 terawatt hours of electricity annually.Subtracting protected areas such as the Grand Canyon, the U.S. has 65 GW of untapped hydropower capacity, if all the streams with hydropower potential were eventua