Cornwall's Eden Project has launched the UK's first operating deep geothermal heating plant since 1986.
The visitor attraction near St Austell will heat its biomes and nursery using the new 4km geothermal system. The process of drilling deep into the granite at the site was completed in 2021 and Eden Geothermal has now finished the heat main and plant.
The well has a vertical depth of 4,871 metres. The measured depth is 5,277 metres, 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.
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.
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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.
To fund the research project, EGL secured £24m funding from a combination of European Regional Development Fund, Cornwall Council and commercial funding from GCP Infrastructure Investments Limited, an investment trust advised by Gravis Capital Management Ltd.
The Growing Point nursery has been built between the geothermal site and the biomes. It serves as a demonstrator of regenerative sustainability and a circular system in both its construction and operation, eliminating the need for a pre-existing off-site nursery, reducing food-miles and dependence on fossil fuels.
Sir Tim Smit KBE, co-founder of the Eden Project, said: “Geothermal is the sleeping giant of renewables: lying not under our noses, but literally under our feet. The Netherlands’ geothermal industry started with heating for greenhouses, and they are now aiming for it to contribute to a quarter of all their heating by 2050.”
Gus Grand, chief executive of EGL, added: “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.’’
Growing Point will enable Eden’s Living Landscapes Team to produce all the plants for the Rainforest Biome, Mediterranean Biome Outdoor Gardens and retail, as well as food for the hundreds of thousands of visitors Eden welcomes every year.
Rob Chatwin, chief executive of the Eden Project, said: “We are developing new ways to grow and new ways to encourage people to think differently about plants and the planet.
“We have built a landmark sustainable nursery - a pillar of our wider ambitions for the future impact and expansion of the Eden Project - and it will help us accelerate massively our mission towards a climate positive future.”
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