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Science

Generating electricity

Geothermal energy

You should be able to outline how electricity is generated from geothermal energy.

Volcanic areas

Several types of rock contain radioactive substances such as uranium. Radioactive decay of these substances releases heat energy, which warms up the rocks. In volcanic areas, the rocks may heat water so that it rises to the surface naturally as hot water and steam. Here the steam can be used to drive turbinesturbines: Revolving machinery with many blades turned by wind, water or steam. Turbines in a power station turn the generators. and electricity generators. This type of geothermal power station exists in places such as Iceland, California and Italy.

Hot rocks

In some places, the rocks are hot, but no hot water or steam rises to the surface. In this situation, deep wells can be drilled down to the hot rocks and cold water pumped down. The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators. The diagram below shows how this works.

cold water is pumped down and steam and water come up

How a generating station creates energy

Advantages

Geothermal energy is a renewable energy resource and there are no fuel costs. No harmful polluting gases are produced.

Disadvantages

Most parts of the world do not have suitable areas where geothermal energy can be exploited.

Back to Energy and electricity index

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