Eden Project starts up UK’s first deep geothermal plant in nearly four decades

E.R. Images / Shutterstock.com

THE UK’s first new deep geothermal project to begin operations in 37 years has come online in Cornwall, providing heat for the iconic Eden Project.

Drilling was finished in 2021 and Eden Geothermal has now completed the heat main and plant. The project uses a single well coaxial system. A 4,000-m vacuum insulated tube has been inserted into the well, which lifts hot water through a heat exchanger. The cooled water is then reinjected back down the well through the outer ring of the tube. The heat is supplied at around 85°C and will be used to warm the Eden Project’s biomes, offices, and a nursery where it grows plants for the site and the food it sells to visitors.

Gus Grand, CEO of Eden Geothermal, said: “This is a big moment for Eden Geothermal and renewables in the UK, but we’ve only just begun: in the race to decarbonise, progress has been slow for heat technologies, behind electricity and transport, but geothermal energy, with its small surface impact, can be used in urban areas and for large institutions, factories, hospitals, universities, and schools. This project is a great demonstration, heating a whole rainforest and commercial nursery, with hopefully a distillery on the way.’’   

The project is the country’s only deep geothermal well currently in operation. There is a system that was installed in Southampton in the 1980s that supplies around 40 GWh/y of heat through an inner city district heating network, including to a hospital and shopping centre, but it is currently offline for repairs.

The UK’s installed capacity lags behind other European countries, including Germany, the Netherlands, and France. In 2020, France produced 2 TWh of heat while Germany has a target to produce around 10 TWh/y of heat from deep geothermal by 2030.

UK geothermal opportunities

A study published last month by member of parliament Kieran Mullan reviewed the opportunities for deep geothermal heat in the UK. He noted that there is a lack of geothermal temperature data for the country as a whole but the data that is available identifies 45 local authority areas that are known to have strong potential. These include areas around Cornwall, Teesside, Yorkshire and the south coast. The report says that it is estimated that with the right support, the UK could have 360 geothermal plants producing 15,000 GWh/y by 2050.

Mullen concludes in his report that one of the reasons the UK has lagged behind Europe is that the country’s drilling and geological expertise has been concentrated in the oil and gas sector. He says that geothermal “provides a unique opportunity for the UKs oil and gas sector to transition their jobs and economic activity to a net zero compliant technology.”

Richard Day, chairman of Eden Geothermal, said: “Geothermal offers a real opportunity for the oil and gas industry to transform itself and become part of the solution. Not only are the expertise and technology for geothermal directly transferrable, but coaxial systems like this could be used to repurpose oil and gas wells.’’

Joerg Baumgaertner, technical delivery partner for the project and CEO of geothermal firm Bestec, said: “The deep single well coaxial heat exchanger which we start today [19 June] is in itself an exciting experiment, which will provide insight and valuable data of this specific technology which we expect to become an important addition to the wide spectrum of geothermal clean energy applications.”

Geothermal energy can also be used to tap valuable byproducts, including the minerals contained in geothermal brines. Last year, Cornish Lithium commissioned the UK’s first pilot plant to directly extract lithium from brines but the future of the company has been cast into doubt after it warned that it would go bust unless it could secure fresh funding by the end of June. Earlier this year, Weardale Lithium announced it had successfully extracted lithium carbonate from geothermal brines using a proprietary direct lithium extraction and crystallisation (DLEC) process.

Lawmakers in the UK are set to debate the government’s plans for geothermal heat and power next month.