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Hydroelectric power stations in the United States are currently the second largest producer of renewable energy in the U.S. after biomass, but the largest renewable source of electricity. Hydroelectric power produced 51% of the total renewable electricity in the U.S. in 2013, and 6.8% of the total U.S. electricity.〔United States Department of Energy, Energy Information Administration, Monthly Energy Review, February 2015〕 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. The amount of hydroelectric power generated is strongly affected by changes in precipitation and surface runoff.〔US Energy Information Administration (January 2010) (''Electric Power Annual 2008'' ), DOE/EIA-0348(2008), p.2-3, PDF file, downloaded 24 January 2010.〕 Hydroelectric stations exist in at least 34 US states. The largest concentration of hydroelectric generation in the US is in the Columbia River basin, which in 2012 was the source of 44% of the nation’s hydroelectricity.〔US Energy Information Administration, (“The Columbia River Basin provides more than 40% of total US hydroelectric generation” ), Today in Energy, 27 June 2014.〕 Hydroelectricity projects such as Hoover Dam, Grand Coulee Dam, and the Tennessee Valley Authority have become iconic large construction projects. ==History== 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.〔Engr. W. E. Herring, U. S. Forest Service, ''Applications of Water Power''. Included in the ''Preliminary Report of the Inland Waterways Commission'', submitted to Congress by Theodore Roosevelt, February 26, 1908. "The application of great water powers to the industrial wants of distant cities is less than ten years old and is still in its infancy, yet in this short space of time stations supplying a large number of cities in the United States with a combined capacity of hundreds of thousands of horsepower have been installed. To reach these industrial centers the water power is electrically transmitted, and in many cases the distance is over 100 miles. This method of utilizing water power has been made possible only by long distance transmission. Fifteen years ago 10 miles was the limit to which electrical power could be transmitted, but at the present time 150 miles is very common and in one case a line of 200 miles is in use. This fact has been the greatest incentive to such water-power developments."〕 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.〔(Energy Timelines Hydropower ), Department of Energy〕〔(History of Hydropower ) Wind and Water Power Program, Department of Energy〕 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 F. 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;〔(Hydroelectric Power ) "The first commercial hydroelectric power station was built in 1882 on the Fox River in Appleton, Wisconsin, in order to provide 12.5 kilowatts of power to light two paper mills and a residence. Paper manufacturer H. F. Rogers developed the station after seeing Thomas Edison's plans for an electricity power station in New York."〕 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 stations 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.〔 Recognizing that the great hydroelectric potential of the Falls exceeded the local demand for electricity, a large power company was established nonetheless at the 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 an alternating current system. The station 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 stations 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 in 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 stations 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hydroelectric power in the United States」の詳細全文を読む スポンサード リンク
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