The most common type of hydroelectric power plant is a dam. A dam, typically a large hydropower system, uses a dam for storage. A dam, typically a large hydropower system, uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine and rotates it, which in turn activates a generator to generate electricity.
The water can be released to meet changing electricity needs or other needs such as flood control, recreation, fish passage, and other environmental and water quality needs. Hydroelectric power plants were built in certain coastal areas, such as the mouth of the River Rance in Brittany, France, to take advantage of the rise and fall of tides. In general, the greater the water flow and the higher the delivery head, the more electricity a hydroelectric power plant can generate. Since the source of hydropower is water, hydroelectric plants are usually located at or near a water source.
Hydroelectric plants range in size from small systems suitable for a single house or village to large projects that generate electricity for utilities. Once a hydropower complex is built, it produces no direct waste and almost always emits considerably less greenhouse gas than fossil fuel power plants. Hydropower plant is the Whiting plant in Whiting, Wisconsin, which was commissioned in 1891 and has a total generation capacity of about 4 megawatts (MW). Although definitions vary, DOE defines large hydroelectric plants as plants with a capacity of more than 30 megawatts (MW).
Hydroelectric plants are usually located in dams that seize rivers, raising the water level behind the dam and creating as high a height as possible. Four years later, the first facility for a system of residential and commercial customers was opened in Wisconsin, USA, and within a decade, hundreds of hydroelectric plants were in operation. The Energy Information Administration publishes electricity generation from pumped storage hydroelectric power plants as negative generation. Electric plant in power generation capacity, is the Grand Coulee water dam on the Columbia River in Washington with 6,765 MW of total generation capacity.
The electricity for pumping can be supplied by water turbines or other types of power plants, including fossil fuels or nuclear power plants. Because hydropower uses water to generate electricity, facilities are usually located on or near a water source. Although definitions vary, DOE defines small hydropower plants as projects that generate between 100 kilowatts and 10 MW. Approximately 1,450 conventional and 40 pumped storage hydropower plants are in operation in the United States.
1900, hundreds of small hydroelectric power plants were in operation as the emerging technology spread around the world.