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Geothermal Energy image
Geothermal Energy

What is geothermal energy?
Geothermal energy is natural energy which comes from the heat of the Earth’s core. Have you ever seen pictures of a volcano or a geyser? If so, then you’ve seen examples of geothermal energy in action! It has been used for thousands of years in some countries for hot water, cooking and heating.

"Geo" means "from the Earth," and "thermal" means "heat," so this type of energy is found under the Earth’s surface. The hot lava from a volcano comes from underground heat – and we can use that same type of heat in our homes.
Geothermal energy is a renewable energy source because the heat is continuously produced inside the earth.

Geothermal energy throughout the world

Deep within the Earth it is very hot and when water flows over hot rocks, hot water and steam are created and escape to the Earth's surface. In places like Iceland, Russia and New Zealand, bubbling mud pools, hot springs and geysers are examples of geothermal energy. Volcanoes are very violent examples of this type of energy.

The hot water and steam created underground can be used to create electricity (by turning turbines) to heat homes and other buildings. The steam is collected, and used to power a generator, in the same way it is used in a coal fired power station.

Around the world people also swim in warm natural springs to help soothe body aches and pains.

Geothermal energy in the UK
Although the heat from deep within the Earth’s core can be used in some places around the world, in the UK, we can make use of the fact that just a few metres below the ground there is a constant temperature between 10-12°C. For most areas, this means that soil temperatures are usually warmer than the air in winter and cooler than the air in summer.

This picture shows the pipes underground in a Ground Source Heat Pump
This shows a Ground Source Heat Pump

Ground source heat pumps use the Earth's constant temperatures to heat and cool buildings. The heat pump is a device that moves heat from one place to another. Some very familiar ones are fridges and air conditioning units.

Some heat pumps use pipes to take the heat from the ground to the building in winter and from the building to the soil in the summer. These can be fitted vertically where a hole is drilled deep down (a borehole) or horizontally where long trenches are dug just a few metres underground in a field or garden (ground loop).

One thing to remember about heat pumps is that they use electricity to change the heat from the ground into heat which we can use in our homes and schools.

As well as ground source heat pumps there are also air source heat pumps which, as the name suggests, work by taking heat from the outside air and turning it into energy for a comfortable temperature inside the house as well as supplying the energy needed for hot water.


  • The energy from the Earth is a renewable resource.
  • Most of the equipment that is fitted with a heat pump is underground which means that it is quiet.
  • The technology is very energy efficient so hardly any of the energy is wasted.


  • Heat pumps can take up space underground if they are fitted horizontally.
  • Heat pumps use electricity which produces carbon dioxide. However a renewable electricity source like Eco Energy or a wind turbine or solar panels can provide their own renewable electricity.