17.3. Energy Resources http://www.ck12.orgRenewable Energy Resources
Renewable resourcesare natural resources that can be replaced in a relatively short period of time or are virtually
limitless in supply. Renewable energy resources include sunlight, moving water, wind, biomass, and geothermal
energy. Each of these energy resources is described inTable17.1. Resources such as sunlight and wind are limitless
in supply, so they will never run out. Besides their availability, renewable energy resources also have the advantage
of producing little if any pollution and not contributing to global warming. The technology needed to gather energy
from renewable resources is currently expensive to install, but most of the resources themselves are free for the
taking.TABLE 17.1: What are the pros and cons of using each of the renewable energy resources
described here?
Renewable Energy Resource Example
Sunlight
The energy in sunlight, or solar energy, can be used to
heat homes. It can also be used to produce electricity in
solar cells. However, solar energy may not be practical
in areas that are often cloudy.Solar panels on the roof of this house generate enough
electricity to supply a family’s needs.
Moving Water
When water falls downhill, its potential energy is con-
verted to kinetic energy that can turn a turbine and
generate electricity. The water may fall naturally over
a waterfall or flow through a dam. A drawback of dams
is that they flood land upstream and reduce water flow
downstream. Either effect may harm ecosystems. Water flowing through Hoover dam between Arizona
and Nevada generates electricity for both of these states
and also by southern California. The dam spans the
Colorado River.
Wind
Wind is moving air, so it has kinetic energy that can
do work. Remember the wind turbines that opened this
chapter? Wind turbines change the kinetic energy of
the wind to electrical energy. Only certain areas of
the world get enough steady wind to produce much
electricity. Many people also think that wind turbines
are noisy and unattractive in the landscape.
This old-fashioned windmill captures wind energy that
is used for pumping water out of a well. Windmills like
this one have been used for centuries.