Geothermal Energy (Cambridge (CIE) IGCSE Physics): Revision Note

Geothermal energy

• Tectonic activity causes areas where the rocks below ground become heated

• Energy in the thermal store of the rocks can be obtained by:

  • Drilling shafts into the Earth's surface to expose the heated rocks

  • Injecting water into the shaft which is heated by the rocks

  • The water is returned via another shaft as steam or hot water

  • The steam turns a turbine, powering a generator that produces electricity.

  • The hot water can be used to heat homes and provide a hot water supply to households

Advantages of geothermal energy

• Geothermal energy is renewable — it comes from the long-term continuous decay of radioisotopes in the Earth's core that will outlive the Earth

• Geothermal power stations do not produce greenhouse gases (such as carbon dioxide) during operation and do not contribute to global warming

• Generating electricity from geothermal energy does not release acidic gases (such as sulfur dioxide) into the atmosphere and does not contribute to acid rain

• Geothermal power stations are reliable because the rocks remain hot for thousands of years so they can consistently produce electricity

Disadvantages of geothermal energy

• Geothermal energy depends on tectonic activity, so there are few suitable locations on Earth

• Drilling can release gases trapped underground, including methane, which is a powerful greenhouse gas

• The initial cost to build the geothermal power station and drill deep into the Earth is extremely expensive

• Most geothermal power stations are smaller than fossil-fuel or nuclear stations