A landmark moment for renewable energy took place at the Eden Project in Cornwall today, Monday, June 19, 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 at the home of the world-renowned Biomes in Cornwall 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 state-of-the art nursery, Growing Point.

The well has a vertical depth of 4,871 metres (just over three 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.

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.

To fund the research project, EGL secured £24-million 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.