Types of Hydropower
An impoundment facility, typically a large hydropower system, uses a dam
to store river water in a reservoir. The water may be released either to
meet changing electricity needs or to maintain a constant reservoir level.
A diversion, sometimes called run-of-river, facility channels a
portion of a river through a canal or penstock. It may not require the use
of a dam.
When the demand for electricity is low, a pumped storage facility stores
energy by pumping water from a lower reservoir to an upper reservoir.
During periods of high electrical demand, the water is released back to
the lower reservoir to generate electricity.
Sizes of Hydropower Plants
Facilities range in size from large power plants that
supply many consumers with electricity to small and micro plants that
individuals operate for their own energy needs or to sell power to
Although definitions vary, DOE defines large hydropower as facilities that
have a capacity of more than 30 megawatts.
Although definitions vary, DOE defines small hydropower as facilities that
have a capacity of 0.1 to 30 megawatts.
A micro hydropower plant has a capacity of up to 100 kilowatts (0.1