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Geothermal energy is a type of renewable energy that uses the Earth’s natural heat to heat homes and businesses or generate electricity.

In this article you can learn about:

• What geothermal energy is
• How it can be used to generate electricity
• Where in the world geothermal energy is used
• What the advantage and disadvantages of geothermal energy are

This resource is suitable for energy and sustainability topics for primary school learners.

In this short video, find out how geothermal energy works and what the advantages and disadvantages of geothermal energy are.

Geothermal power plants are built where there are underground reservoirs of water around fault lines in the Earth’s tectonic plates.

The gaps between the plates allow magma to heat up the water.

Learn what tectonic plates and fault lines are here: Tectonic movement

In a geothermal power plant:

• The steam created from the heat of the water is drawn up to the surface.

• The kinetic energy from the steam turns turbines in the power plant.

• The generators then turn this energy into electricity.

• The cooling tower cools the steam and it becomes water again and then the water is piped back into the reservoir where the process can start again.

Most geothermal power plants are located in parts of the world that sit on fault lines between tectonic plates. They have lots of volcanic activity and the Earth's crust is thinner, which helps create the conditions needed to capture geothermal energy more easily.

Countries like Iceland, New Zealand and Indonesia can use geothermal energy because they are on these fault lines.

Geothermal power plants work best in places where there are fault lines between tectonic plates and less drilling is needed to reach underground stores of hot water.

Building geothermal plants in the UK could work but would be more expensive to set up. Pipes might have to stretch hundreds of metres or more underground to reach sources of hot water.

Two projects in Scotland (in Shettleston in east Glasgow and Lumphinnans in Fife) already work in a similar way. Instead of drilling new pipes, each use the heat from water in abandoned mines to heat a small number of homes.

Countries like Scotland can also benefit from geothermal energy by using ground source heat pumps. These use shallow underground pipes to warm water that can then be used to help heat buildings.

The lower you go underground, the warmer the ground is, so pumping fluid through underground pipes can heat it up. We can use this to provide central heating and hot water for our homes.

This is another example of geothermal energy.

Advantages of geothermal electricity

• Geothermal power is more environmentally friendly than the use of fossil fuels and its carbon footprint is low.

• It is a source of renewable energy that will not run out. The hot reservoirs within the Earth are naturally refilled, making it both renewable and sustainable.

• There are a lot of geothermal sources we haven't yet explored so there is a lot more energy to find and use.

Learn about the difference between renewable and non-renewable energy: What is renewable and non-renewable energy?

Disadvantages of geothermal electricity

• Geothermal power plants can't be built everywhere. They are easiest to set up near fault lines, and become more expensive and difficult to set up the further down you have to drill to reach hot water.

• Greenhouse gases can be released from underground during drilling into the ground to build geothermal power plants. These gases are released into the atmosphere naturally but this happens more quickly near geothermal plants.

• Building geothermal power plants (which involves digging into the Earth) can trigger earthquakes.

Find out what causes earthquakes with Isla and Connor: Tectonic Movement: Earthquakes

Earth’s crust – The surface layer of the Earth. It covers the whole planet, both land and sea. It is made of rocks and minerals and can be anywhere between 1.5 to 70 km thick.

Tectonic plates – Large slabs of solid rock that form the Earth’s crust. They are like the pieces of a large jigsaw puzzle that fit together and are separated by fault lines. Tectonic plates slowly float around on a thick layer of hot, molten rock called the mantle. The movement of tectonic plates can create mountains and seas or cause earthquakes and volcanic eruptions.

Fault lines – Long cracks in the Earth’s crust. These cracks form gaps between huge slabs of rocks called tectonic plates. Earthquakes and volcanoes occur most along fault lines.

Mantle – The thickest layer of the Earth’s interior. It lies between the Earth’s core and the Earth’s crust. It is extremely hot and is mostly made up of molten rock.

Magma – Molten rock that is located deep below the Earth’s surface. Magma can escape when deep cracks in the Earth's crust appear or when volcanoes erupt. Magma that reaches the Earth's surface is called lava.

Natural disaster – An event that happens as a result of natural processes. A natural disaster cannot be caused by humans. Volcanoes, earthquakes and tsunamis are examples of natural disasters that can be caused by the movement of the tectonic plates.

Turbine – A turbine is a machine that turns the movement of liquid or gas into energy that can be used. In a simple turbine water or air push against turbine blades and spin them round. The spinning blades turn a long pole called a shaft. The shaft can then turn other pieces of machinery, such as a generator that is used to produce electricity.

Generator – A machine that is used to make electricity. When the generator head is turned, this energy is converted to electrical energy.

Cooling tower – A large tower that is used to cool the steam, turning it back to water, which is then returned to the reservoir.

Find countries that could most easily use geothermal energy

1. Find two maps online: a map of the world and a map of the world’s fault lines.

2. Use the maps to find countries that have the most potential to create power using geothermal energy.

3. Pick two or three countries : Do they currently have geothermal power plants? If they do, what is this energy is used for?