Geologists at the British Geological Survey (BGS) published a research paper on Thursday mapping out regions in central and southern England with the greatest potential to generate geothermal energy.

The paper maps formations of Early Carboniferous limestones (ECLs) that host active geothermal systems which naturally heat up water deep below the Earth’s surface. It covers central and southern England at depths of over 4km below ground.

Equivalent rock formations have been successfully developed to harness geothermal energy in Belgium and the Netherlands. There, they supply heat networks, but the ECLs have yet to be fully assessed as a geothermal resource in the UK.

Low- to medium-temperature geothermal resources are known in the UK, because water rises to Earth’s surface in places such as Bath Spa. However, “little is understood about the wider extent and reach of these limestones, which lie deep below the surface of the ground, and about the potential to recover heat from their deep thermal waters,” Dr Timothy Kearsey, BGS sedimentary geologist, explained in a press release.

The BGS team used 3D modelling methods to assess the depth, distribution, and geothermal potential of regions in England, producing maps that demonstrate the total heat in place, enabling an estimation of recoverable heat distribution.

According to the paper, there lays the potential in these regions to recover thermal heat equivalent to between 106GW and 222GW. The largest resources sit underneath the East Midlands and Greater Manchester, as well as the Humber and Cheshire regions.

Dr Kearsey said: “This is very exciting. Until now, Early Carboniferous limestones had yet to be fully quantified as a geothermal resource in Britain. Our research shows these limestones could play host to many active geothermal systems across central and southern Britain”.

However, further research is still required to understand the resource fully, and to identify areas with sufficient flow rates for successful development of geothermal infrastructure.

“What we do know is that the Early Carboniferous limestone may offer significant potential as a resource for deep geothermal energy across large parts of central and southern Britain. These maps are very encouraging, particularly as large-scale exploitation of heat is critical for the successful decarbonisation of the UK’s energy mix,” Dr Kearsey concluded.