Different types of hydroelectric power used in different parts of the world

There are three types of hydroelectric installations used in the world:
• Storage
• Run-of-river
• Pumped-storage facilities.


Storage facilities use a dam to capture water in a reservoir. This stored water is released from the reservoir through turbines at the rate required to meet changing electricity needs or other needs such as flood control, fish passage, etc.

Drawing courtesy of U.S. Department of Energy

Run-of-river facilities use only the natural flow of the river to operate the turbine. If the conditions are right, it can be constructed without a dam or with a low diversion structure to direct water from the stream channel into a penstock.


(Image taken from: http://www.nwcouncil.org/Library/2004/2004-1/Wanapum_sm.jpg )This Run-of-River project is in Idaho Falls, Idaho. Run-of-River Projects– utilize the natural flow of the river.

(Image taken from http://www.switchinggears.com/images/tazimina_small.jpg )
This picture shows The Tazimina Project in Alaska which did not require a dam.
Use of Diversion Hydropower– Channels a portion of the river through a canal.

Pumped-storage facilities, an innovation of the 1950s, have specially designed turbines. These turbines have the ability to generate electricity the conventional way, that is, when water is delivered through penstocks to the turbines from a reservoir. However, they can also be reversed and used as pumps to lift water from the powerhouse back up into the reservoir where the water is stored for later use. During the daytime when electricity demand suddenly increases, the gates of the pumped-storage facility are opened and stored water is released from the reservoir to generate and quickly deliver electricity to meet the demand. At night when electricity demand is lowest and there is excess electricity available from coal or nuclear electricity generating facilities the turbines are reversed and pump water back into the reservoir. Operating in this manner, a pumped-storage facility improves the operating efficiency of all power plants within an electric system.

Drawing courtesy of U.S. Department of Energy