Geothermal Energy (Cambridge (CIE) IGCSE Physics)

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 can be used to turn a turbine and generate electricity

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

Geothermal power station

Cold water is heated by the rocks and returned as hot water or steam, which can be used to generate electricity

Advantages of geothermal energy

• Geothermal energy is renewable

• 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

• Methane (natural gas) is found in spaces between rocks and can be forced out when water is injected into the rocks (fracking)

  • Methane is a greenhouse gas which contributes to global warming (even without combustion)

• Geothermal power stations are expensive to build

• Geothermal power stations are small so they are not suitable for large-scale electricity production

• Geothermal power stations are not very efficient (around 12%)