Hydroelectric power is generated by the use of gravity, using falling or flowing water as a source of energy. Hydropower is the production of electrical power through the use of gravitational force. As the most widely used form of renewable energy, it accounted for 16 percent of global electricity production in 2010 - 3,427 terawatt hours. It is expected to increase by about 3.1% annually for the next 25 years. Approximately 32 percent of the world's hydropower is generated in the AsiaPacific region, which produces hydropower in 150 countries. The Chinese hydroelectric industry is the world's largest, producing 721 terawatt-hours of energy in 2010, which represents 17 percent of domestic energy consumption. Currently, there are four hydroelectric power plants that are larger than 10 GW: the Three Gorges Dam and Xiluodu Dam in China, the Itaipu Dam in Brazil, and the Guri Dam in Venezuela. Hydroelectricity is relatively cheap, making it a competitive source of renewable energy. An average hydroelectric station with a capacity over 10 megawatts costs between 3 and 5 cents per kilowatt-hour. Furthermore, the amount of electricity produced by the station can be adjusted up or down very quickly to meet changing energy requirements. Damming However, disrupts river flows and harms local ecosystems, and people and wildlife are often forced to move when large dams and reservoirs are built.In contrast to fossil fuelpowered energy plants, hydroelectric projects produce no direct waste and emit considerably less carbon dioxide (CO2) than those that are powered by fossil fuels.

Keywords : Hydroelectric, Renewable Energy, Hydropower.