PUMPED STORAGE
Another type of hydropower called pumped storage works like a battery, storing the electricity generated by other power sources like solar, wind, and nuclear for later use. It stores energy by pumping water uphill to a reservoir at higher elevation from a second reservoir at a lower elevation. 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 and turns a turbine, generating electricity.
SIZES OF HYDROELECTRIC POWER 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 utilities.
LARGE HYDROPOWER
Although definitions vary, DOE defines large hydropower as facilities that have a capacity of more than 30 megawatts (MW).
SMALL HYDROPOWER
Although definitions vary, DOE defines small hydropower as projects that generate 10 MW or less of power.
MICRO HYDROPOWER
A micro hydropower plant has a capacity of up to 100 kilowatts. A small or micro-hydroelectric power system can produce enough electricity for a home, farm, ranch, or village.