UK’s first operational deep geothermal project in 37 years turns on the heat

Credit: Toby Smith, Eden Geothermal Ltd

A landmark moment took place at the Eden Project in Cornwall on 19 June as the UK’s first operating deep geothermal heating plant since 1986 was opened and is now generating heat.

The process of drilling deep into the granite was finished in 2021, and Eden Geothermal Ltd (EGL) has now completed the heat main and plant and is ready to supply heat to the Eden Project and its new nursery, Growing Point.

Gus Grand, CEO of EGL, commented: “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 well has a vertical depth of 4,871 metres (just over 3 miles). The measured depth – the actual length of the well – is 5,277 metres (nearly 3.3 miles), making it the longest well under UK soil.

The geothermal heat system is a single well coaxial system. A 4000m vacuum insulated tube has been inserted into the well, lifting hot water from deep below. This is passed through a heat exchanger and the cooled water is then re-injected into the well via the outer ring.

Richard Day, Chairman of EGL, commented: “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.”

Credit: Eden Project

The heat is delivered via a 3.8km heat main, at around 85 degrees Centigrade, which will supply Growing Point and Eden’s Biomes and offices.

The geothermal project has been delivered by Eden Geothermal Limited (EGL), a three-way partnership between Eden Project Limited, EGS Energy Limited, a geothermal development and consultancy group, and BESTEC (UK) Limited, affiliated with BESTEC GmbH, the specialist geothermal developer and drilling advisor.

Glenn Caplin-Grey, Chief Executive of the Cornwall and Isles of Scilly Local Enterprise Partnership, added: “This is a landmark moment in the development of geothermal energy in Cornwall and the UK.

“It is further evidence of its huge potential role in the energy transition away from fossil fuels, and how Cornwall is leading the way in the development of renewable technologies, from floating offshore wind to critical minerals for domestic battery production.’’