Hydroelectric power in the United States is currently the largest producer of renewable power in the U.S. It produced around 66.8% of the total renewable power in the U.S. in 2008.[1]
In 2008 hydroelectric produced 6.4 % of the nation's total electricity. According to IEA the United States was the 4th in the hydroelectricity power in the world in 2008 after China, Canada and Brazil. Produced hydroelectricity was 282 TWh (2008). It was 8.6 % of the world total hydropower. The installed capacity was 100 GW in 2007. In 2008 the United States produced total 4 344 TWh electricity (21.5 % of the world total) and imported 33 TWh.[2]
The amount of hydroelectric power generated is strongly affected by changes in precipitation and surface runoff.[3]
Hydroelectric plants exist in at least 34 US states. Hydroelectricity projects such as Hoover Dam, Grand Coulee Dam, and the Tennessee Valley Authority have become iconic large construction projects.
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The earliest hydroelectric power generation in the U.S. was utilized for lighting and employed the better understood direct current (DC) system to provide the electrical flow. It did not flow far however, with ten miles being the system's limit; solving electricity's transmission problems would come later and be the greatest incentive to the new hydroelectric water-power developments.[4]
The first DC powerhouse was in Grand Rapids, Michigan, where the water turbine at the Wolverine Chair factory was attached to a dynamo using a mechanical belt drive to illuminate sixteen street lights.[5][6] This occurred in 1880, the same year Thomas Edison produced the long-lasting incandescent filament light bulb, which was a safety and convenience improvement over existing candles, whale oil lamps and kerosene lamps inside buildings. In 1881, also using DC for lighting at Niagara Falls, Jacob Schoellkopf diverted part of the output from his waterwheel-powered flour mills to drive one of Charles Brush's improved generators to provide nighttime illumination for the tourists. Previously the attraction had been illuminated by burning bright calcium flares but arc-lights proved a better and cheaper alternative. In 1882, the world's first commercial central DC hydroelectric power plant provided power for a paper mill in Appleton, Wisconsin;[7] just months later the first investor-owned electric utility, Edison Illuminating Company, completed the first fossil fueled electrical power plant in New York City, to compete with hydroelectric power close to an area of high demand. By 1886, between 40 to 50 hydroelectric plants were operating in the United States and in Canada, and by 1888 about 200 electric companies relied on hydropower for at least part of their generation.[6]
Recognizing that the great hydroelectric potential of the Falls exceeded the local demand for electricity, a large power company was established nonetheless at a prime location for development; it awaited the prospect of an effective long-distance power transmission system. Westinghouse Electric won the competition, developing their plans around Nikola Tesla's 1888[8] alternating current system. The plant was completed in 1895 and in 1896, electricity transmission 20 miles away to Buffalo, New York began. This event also began the rise to dominance of the AC system over Thomas Edison's direct current methods. Multiple permanent hydropower plants still exist on both the American and Canadian sides of the Falls, including the Robert Moses Niagara Power Plant, the third largest in the United States.
The need to provide rural development in the early 20th century was often coupled to the availability of electric power and led to large-scale projects like the Tennessee Valley Authority which created numerous dams and, sometimes controversially, flooded large areas. In the 1930s, the need for power in the Southwest led to the building of the largest concrete construction in the world at that time, the Hoover Dam. The Grand Coulee Dam was both a power and irrigation project of the 1930s that was expanded for military industrial reasons during World War II which also saw other dams such as the TVA's Fontana Dam built.
Dam building peaked in the 1960s and few dams were built the 1970s. The growing awareness of environmental issues with dams saw the removal of some older and smaller dams and the installation of fish ladders at others. Instead of new dams, repowering old plants has increased the capacity of several facilities. For instance, Hoover Dam replaced its generators between 1986 and 1993. The need to alter downstream waterflow for ecological reasons (eliminating invasive species, sedimentation, etc.) has led to regulated seasonal drawdowns at some dams, changing the availability of water for power generation. Droughts and increased agricultural use of water can also lead to generation limits.
Another application of hydroelectricity is Pumped-storage hydroelectricity which does not create a net gain in power but enables peak demand balancing. Water is pumped from a lower elevation source into a higher one and only released through generators when electric demand is high. In 2009 the United States had 21.5 GW of pumped storage generating capacity, accounting for 2.5% of baseload generating capacity.[9] Bath County Pumped Storage Station is the largest such facility in the world. Other plants of this type include Raccoon Mountain Pumped-Storage Plant, Bear Swamp Hydroelectric Power Station and Ludington Pumped Storage Power Plant on Lake Michigan and previously the largest in the world.
| Name | Year of completion | Total Capacity (MW) | Max annual electricity production (TW-hour) |
Area flooded (km²) | |
|---|---|---|---|---|---|
| 1 | Grand Coulee | 1942/1980 | 6,809 | 20[10] | |
| 2 | Chief Joseph Dam | 1958/73/79 | 2,620 | ||
| 3 | Robert Moses Niagara Power Plant | 1961 | 2,515 | ||
| 4 | John Day Dam | 1949 | 2,160 | ||
| 5 | Bath County PSP | 1985 | 2,100 | 3.32 | |
| 6 | Hoover Dam | 1936/1961 | 2,080 | ||
| 7 | The Dalles Dam | 1981 | 2,038 |