Energy world

Energy sources: Geothermal

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

What is it?

Geothermal energy is a form of renewable energy that is not dependant on the Sun, but on heat that comes from deep below the surface of the Earth in the layer called the mantle. Molten rock from the mantle can rise in places bringing the mantle's heat nearer the surface and can sometimes even erupt onto the surface as volcanoes. In certain places, like Bath with its famous hot spring baths, natural mineral water can percolate deep down beneath the surface until it gets near to hot areas, is heated up and then returns to the surface as natural hot springs.

How is it used to generate electricity?

These natural hot waters can be used for geothermal energy. More often though man-made holes are drilled down to a hot area beneath the surface so that water can be pumped down, where it is heated and then drawn up again, and used to heat homes or (if really hot) to drive steam turbines and generate electricity.

Where can you find it?

Volcanic places, like Iceland.

Advantages and disadvantages of using geothermal energy to generate electricity


Geothermal energy does not produce any pollution

Running costs for a geothermal power station are very low


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 plants in the UK?

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

How much does it cost to produce?

No reliable figures are available at present.

What is the carbon cost?

The process does not produce any carbon dioxide.

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.