Unlike wind and solar resources, which are more dependent upon weather fluctuations and climate changes, geothermal resources are available 24 hours a day, 7 days a week. The temperature at the centre of the Earth is around 5000 degrees Celsius – hot enough to melt rock. Even just a few kilometres down the temperature can be over 250 degrees Celsius. In general, the temperature rises one degree Celsius for every 30–50 metres you go down, but this varies depending on location.

At the time of writing geothermal power is in its infancy, with the US and Japan leading the way in terms of production. Iceland is totally self-sufficient in geothermal power and electricity and is already heating a large number of homes with this power ...

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