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.
Red areas show heat-producing outcrops of granite in Cornwall
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 2000 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.
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.
Heat flow in the UK, (BGS, 1986; this version from Busby, 2010).