A hydropower plant (HPP) converts the energy of moving water into electricity using turbines and generators, with types including dammed reservoir, run-of-river, and pumped storage facilities. While HPPs offer benefits like cheap electricity and renewable energy with no atmospheric pollution, they also present challenges such as attachment to water sources, potential negative environmental impacts on ecosystems, and significant construction costs.
There are three types of hydropower facilities: impoundment, diversion, and pumped storage.
Although not all dams were built for hydropower, they have proven useful for pumping tons of renewable energy to the grid. The other dams are used for recreation, stock/farm ponds, flood control, water supply, and irrigation.
Hydropower plants range in size from small systems suitable for a single home or village to large projects producing electricity for utilities.
Impoundment
The most common type of hydroelectric power plant is an impoundment facility. An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. The water may be released to meet changing electricity needs or other needs, such as flood control, recreation, fish passage, and other environmental and water quality needs.
Diversion
A diversion, sometimes called a “run-of-river” facility, channels a portion of a river through a canal and/or a penstock to utilize the natural decline of the river bed elevation to produce energy. A penstock is a closed conduit that channels the flow of water to turbines with water flow regulated by gates, valves, and turbines. A diversion may not require the use of a dam.
Pumped Storage
Another type of hydropower, called pumped storage hydropower, or PSH, works like a giant battery. A PSH facility is able to store the electricity generated by other power sources, like solar, wind, and nuclear, for later use. These facilities store energy by pumping water from a reservoir at a lower elevation to a reservoir at a higher elevation.
When the demand for electricity is low, a PSH facility stores energy by pumping water from the lower reservoir to an upper reservoir. During periods of high electrical demand, the water is released back to the lower reservoir and turns a turbine, generating electricity.
Source: energy.gov
