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Hydroelectric Energy: Classroom Activities

Locating Hydroelectric Power Plants


To develop a better understanding of where hydroelectric energy is generated in the United States.

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Background Information

Hydroelectricity is produced by converting the kinetic energy of moving water to electrical energy. The most common method for doing this is to build a dam across a large river. Flowing water from the river builds up in a reservoir behind the dam. The water level behind the dam is higher than the river below. The water falls through a large pipe, called a penstock, and applies pressure against the blades of a turbine, causing them to spin, which drives a generator to produce electricity.

The best sites for building hydroelectric power plants that use dams to generate electricity are fast-moving rivers or streams and areas with consistent rainfall. This ensures that the flow of water is sufficient enough to fill the dam. In addition, a strong flow of water compensates for water that is lost from the reservoir due to evaporation.

Hydroelectric power plants also require sites that are hilly or mountainous and with valleys or depressions for building a dam to create a reservoir. The large volume of water that is stored in a reservoir exerts enormous pressure on the walls of the dam. The walls of the dam must be strong enough to contain this force. The best location along the path of a river is a river canyon or where there is narrowing of the river. Additionally, the bedrock on which a dam is to be constructed should be stable and strong enough to sustain the weight of the dam and the pressure of the water stored in the reservoir.

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Activity Overview

Students analyze a map that shows the location of hydroelectric power plants and major waterways in the continental United States.

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Materials and Equipment

Hydroelectric Energy map (below) - color copies or projected

Hydroelectric Energy map
Source: The American Geological Institute, EarthComm: Project-Based Space and Earth System Science, 2nd Edition, Armonk, New York: It's About Time, 2012, pg. 731.

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  1. Provide copies of the Hydroelectric Energy map to students. Alternatively, project the map for the class to see.
  2. Have students examine the map and complete the following:
    1. Which parts of the country have the most hydroelectric power plants?
      The most hydroelectric power plants are found in the west and northeast. The eastern part of the United States has a fairly large number.
    2. Which parts of the country have few hydroelectric power plants?
      The central part of the United States has few hydroelectric power plants.
    3. Where does your community fall in terms of the locations of hydroelectric power plants?
      Answers will vary.
    4. Which states have the most hydroelectric power plants?
      Most of the big hydroelectric power plants in the United States are in California, Oregon and Washington.

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