Energy nation

Geothermal

Status: Renewable, but overuse can damage boreholes for many years

What is it?

Heat comes from deep below the surface of the Earth in a layer called the mantle. Molten rock from the mantle can rise, bringing heat nearer to the surface. In some places, water deep beneath the Earth’s surface is heated up. This water returns to the surface as natural hot springs and can be used for geothermal energy.

How is it used to generate electricity?

Man-made holes are drilled down to a hot area beneath the surface so that water can be pumped down. It is heated and then drawn up again. It can be used to heat homes, or if really hot, to drive steam turbines to generate electricity.

Where can you find it?

Volcanic places, like Iceland.

Advantages and disadvantages of using geothermal energy to generate electricity

Advantages

  • Geothermal energy does not produce any pollution
  • Running costs for a geothermal power station are very low

Disadvantages

  • It is difficult to find suitable sites to put a geothermal power station
  • If not carefully managed, a borehole can ‘run out of steam’ and may not be useable for several decades
  • Dangerous gases and minerals can come out of a borehole, which may be difficult to dispose of

How many stations in the UK?

There are none in the UK that produce electricity, but one in Southampton supplies heat.

The future?

The potential for electricity generation is limited because the UK is not volcanic, but geothermal energy may be used for heating on a small scale.