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What is geothermal energy and how does it work?

Geothermal energy is the thermal energy that comes from the natural heat in the earth’s core.

Geothermal energy

The core of the Earth can reach temperatures of up to 6,000˚C. Even just a few kilometres beneath the Earth’s surface temperatures can reach up to 250˚C. So even if the ground feels cool, there’s valuable heat energy there. Innovative geothermal energy technology helps to harness this heat.  

It works in three main ways:

  1. Direct geothermal energy: where hot water is pumped directly into buildings from hot springs or geothermal reservoirs and used for heating.
  2. Geothermal power plants: where hot water and steam from deep beneath the earth is piped into wells and used to generate electricity in a power plant.
  3. Geothermal heat pumps: a small-scale source of renewable energy for homes and office buildings. This is also known as a ground source heat pump.

You might be surprised to learn that even here in the UK, there’s potential to generate a lot of heat.

The most popular domestic geothermal technology is the third kind; ground source heat pumps. These work by using pipes that are buried in the garden to extract heat from the ground. The pump circulates a mix of water and antifreeze around the loop of pipe (a ‘ground loop’), which absorbs the heat, which is then passed back into your home for use in central heating or warming water tanks.

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