The inclusion of geothermal in the energy mix for the UK, particularly for heat, would make a significant contribution to the ‘green recovery’ and meeting our emissions targets and low-carbon economy goals.

The UK has not traditionally been thought of as a geothermal country but it does have geothermal resources. The granites underlying Cornwall and west Devon have abnormally high geothermal gradients that make electricity generation possible.

​Elsewhere, in other granitic rocks and in sedimentary basins, there are geological and thermal conditions that allow the production of renewable heat that could meet the needs of large residential and commercial developments or specific industrial and agricultural applications. In the depth range 500m to 2500m, rock temperatures of 30°C to 100°C can be found in many places and they can be accessed with readily available drilling technology.


Even low to moderate ground temperatures just below the surface can be harnessed for heating (and cooling) using ground source heat pump systems. This section of the UK market is well established, with xxxx systems installed over the last 20 years or so.

Flooded mines also represent a very significant source of low grade geothermal energy that could be harnessed for both heating and cooling.

See below for more details on the different types of geothermal energy used in the UK.


Heat flow in the UK, (BGS, 1986; this version from Busby, 2010).

Red areas show heat-producing outcrops of granite in Cornwall

Types of geothermal in the UK



Ground Source Heat Pumps

Mine water

Deep geothermal

Ground Source Heat Pumps:

  • Heating & Cooling

  • Commercial & domestic applications

  • Depths of 0 - 100m

  • Temperatures range from 10 - 25ºC

  • Open-loop or closed-loop systems

  • Available across 100% of the UK

Mine water:

  • Heating & Cooling

  • Commercial & domestic applications

  • Depths of 0 - 900m

  • Temperatures range from 10 - 40ºC

  • There are 23,000 abandoned mines in the UK, many of them close to urban areas and heat loads


  • Heating & Cooling

  • Commercial & domestic applications

  • Depths of 0 - 2500m

  • Temperatures up to 100ºC

  • May be drilled specifically for geothermal or re-purposed abandoned exploration holes

  • Hot water co-produced with oil or gas in operating fields

The benefits of Geothermal Energy:

Very low to zero carbon emissions when in operation

Small footprint on the surface

Baseload power - no intermittency issues

Green, sustainable and renewable energy source

Deep Geothermal/EGS:

  • Electricity Production

  • Heating & Cooling

  • Commercial applications

  • Depths of 2000 - 5000+m

  • Temperatures range from 100 - 200ºC

  • Available in areas with high heat production granites. 

Wherever you are in the world, the rocks get hotter with depth.

This is known as the geothermal gradient