UNIT 5: Earth and Space, Part 2
Lesson 3: Alternative Energy Resources
Hydroelectric Energy
Hydroelectric energy
is also an alternative energy resource.
Hydro- is a prefix meaning water. Moving water contains
energy. The amount of usable energy in moving water depends
on how s
wiftly the water moves. Most often, a hydroelectric
plant uses a dam to produce or generate electricity.
Think about—
A river flows toward the ocean.
A dam is built on the river.
The dam holds back the water in the river.
The water is collected in a reservoir.
Photograph by Karen Thompson
Lake Travis, Austin, Texas
Water is released from the reservoir. The moving water quickly
flows through turbines at the base of the dam. The force of the
moving water causes the turbines to turn.
Remember the pinwheel? Moving water caused the blades of
the pinwheel to turn. As the turbines at the base of the dam
turn, a generator converts, or changes, the energy of moving
water into electricity.
