How a hydroelectric plant works
Hydroelectricity cannot really be considered an alternative form of
energy because it produces a significant amount of U.S. energy. Dams are
used to trap and store water. See Figure 5-12. A gate lets the water in.
When the gate is open, the water rushes through a tunnel known as a
penstock. At the end of the penstock is a water turbine. The turbine turns
as the water comes rushing in, causing the generator to spin. The mechan-
ical energy that spins the generator is converted into electricity. The elec-
tricity is then sent off to power companies through electric lines and
distributed to customers. This process is described in much greater detail
in Chapter 8.
Undershot
waterwheel: A
waterwheel that
does not require a
significant eleva-
tion change and
primarily makes
use of the force of
flowing water.
Hydroelectric
energy: The use of
flowing water from
waterfalls and
dams to produce
electricity.
Penstock: A dam
tunnel through
which stored water
rushes to a water
turbine.
107
Figure 5-12. Hydroelectric power generation. A—Very large dams, such as
the Hoover Dam in Nevada, impound huge amounts of water for use in
electrical generation. (U.S. Department of Agriculture) B—This schematic
shows how water stored behind a dam is used to drive turbines and electrical
generators.
Gate Dam
Penstock
Generator
Turbine
Water in
To customer
A
B
Renewable and Inexhaustible Energy Sources