5.7. Renewable Energy Resources http://www.ck12.org
FIGURE 5.19
This large machine is harvesting and
grinding plants to make ethanol.Geothermal Energy
Geothermal energy is thermal (“heat”) energy from below Earth’s surface. It can be used to heat homes or generate
electricity. A geothermal system pumps water underground where it is heated and then pumps the warm water back
to the home or power plant (seeFigure5.20). The thermal energy of the water can be used directly to heat the home.
Or it can be used to produce steam and generate electricity. Installing a geothermal system can be expensive because
of the need to drill through underground rocks, but the energy it uses is free.
FIGURE 5.20
This power plant uses geothermal en-
ergy.