Energy Explainers: What is Geothermal Energy? (Exeter City Futures)
Energy Independence 2025, by Exeter City Futures - a Community Interest Company, identifies the options for increasing renewable energy generation within the Exeter region. In this Energy Explainers blog they introduce Geothermal energy, giving a very good explanation and touting its potential to power the south-west of England.
While many people consider heat pumps to be a source of geothermal energy, the heat they transfer is actually heat from the sun which is stored underground. So technically they are classed as solar power. To harness the full power of geothermal we need to dig a little deeper.
There’s a huge potential for generating energy from hot rock granite sources. The technology for capturing this energy still needs to be validated, but solutions are being tested including a geothermal power plant at the Eden Project in Cornwall.
To access the heat that’s trapped in gaps between granite in the ground two holes are drilled. Each hole is very narrow, but goes several kilometers below the ground. Cold water is pumped down one hole into the gap where it’s super hot – around 180°C. The hot water is then pumped back up the other hole where it runs through a turbine to make electricity.