How Does Hydroelectricity Work?
Types of Hydropower Facilities
Uses a dam to store water. Water may be released either to meet changing electricity needs or to maintain a constant reservoir level.
Channels a portion of the river through a canal or a penstock but may require a dam.
Pumps water from a lower reservoir to an upper reservoir at times when demand for electricity is low. During periods of high electrical demand, the water is released back to the lower reservoir to generate electricity.
The Hydrologic Cycle
Water constantly moves through a vast global cycle, in which it evaporates from lakes and oceans, forms clouds, precipitates as rain or snow, then flows back to the sea. The energy of this water cycle, which is driven by the sun, is tapped most efficiently with hydropower.