Hydropower is electricity produced from flowing water. As a result, hydropower output varies widely according to rainfall. Most hydropower is produced at large facilities built by the Federal Government, such as Grand Coulee Dam on the Columbia River in Washington State – the largest single electric power facility in the United States. Most of the largest dams are located on rivers in the western United States, but there are numerous smaller facilities operating around the country.
Hydropower production varies from year to year, depending on precipitation. In 2007, hydropower accounted for 6% of the net U.S. electricity generation. It also accounted for 36% of the renewable energy consumption, more than any other renewable energy source.
The newest “wave” in hydropower technologies is being developed to harness the energy in ocean tides, waves, and currents.
Source: Energy Information Administration