Renewable Energy

1 Have you ever seen steamspoutinghigh into the air froma geyser?Geysers are poweredby geothermal energy. (Thewordgeo=earth and theword thermal = heat, so geothermal = earth’s heat.) This heat energy can be used to make electricity. Here’s how it works: The earth has many layers. The center (core) is extremely hot. Heat transfers from thecore toanearby layer of rockcalled themantle.When temperatures andpressures becomehighenough,someof themantlerockmeltsandbecomesafluidcalledmagma. Insomeplaces,magmarisesintocracksintheearth’souterlayer,orcrust.Geysersform when the hot, flowing magma heats underground water. Geothermalpowerplants drillwellsintoareaswherewaterisheatedbynearbymagma. The wells capture the hot water and steam, and use it to run turbine generators. Under pressure Advantages • Geothermal energy does not produce CO 2 emissions. • Geothermal energy generation is less expensive to build and operate than fossil fuel power plants. Challenges • Finding good geothermal sites can be difficult. • Drilling geothermal wells can be costly, although new drilling methods could bring these costs down considerably. In the illustration of the earth at the right, use four different colors to drawand label thelayersof theearth: thecore, themantle, the magma, and the crust. If you want, include a geothermal geyser! Bonus: Use the Internet or your school library to find out where geothermal activity is found in the world. Where is it harnessed to produce electricity? Layer It On Geothermal 13