Eden Geothermal Project – Phase One

The project is building on knowledge of the deep geothermal resource in Cornwall by providing greater understanding of the geology at depth, enabling resources in the region to become characterised as reserves.  

When testing of our first well, EG-1, is complete, there will be a period of heat production from this single deep well.  The hot water produced will be used to provide direct heat to the facilities at Eden, demonstrating the benefits of greenhouse gas (GHG) savings achievable from this specific project, while also indicating the long-term level of GHG savings that can be achieved from a two-well system. 

It is anticipated that this will provide a pivotal first step in the creation of a new renewable and industry sector for the county and for the UK, as the greater understanding of the conditions deep in the granite will enable the subsequent development of another 4,500-metre well (EG-2) and a combined heat and power plant. 

Phase One project programme

The main stages of phase one of the Eden Geothermal Project are: 

  1. Preparation and finalisation of design and procurement of specialist services; 
  1. Site works;
  1. Drilling, completion and testing of the first deep well;
  1. Installation of a heat main to Eden;
  1. Heat production / supply to Eden, with greenhouse gas savings calculation, from the first well. 


This stage, now complete, included finalising the site and well design, recruitment and the procurement of the main services required for the Project.  

Site works 

The enabling works required to prepare the site for drilling were undertaken by a specialist contractor. This work included: ground levelling; erection of a perimeter fence; creation of site access; construction of roadways, drill pad, wellhead cellars and lagoons; site drainage and flood alleviation; erection of site buildings; installation of seismic monitoring network; installation of services and conductor pipe. A dedicated public viewing area was also created. 

Drilling EG1 

Drilling started in May 2021 and was completed in October the same year. It took 162 days. The first deep well (EG-1) is a deviated well drilled to a vertical depth of 4,871 metres (measured depth or total length of 5,277m) using conventional rotary drilling with muds. The upper three sections have been lined with steel casing, but the bottom section has been left as an open hole.  

Eden Geothermal Phase One wellbore diagram

For more detail about how we developed and are testing EG-1, visit our Drilling and Operations page.

Well testing 

Our well testing programme is providing, essential information on the hydrogeological characteristics of the target rock zone. It has been designed by the team in conjunction with University of Exeter, in response to the conditions encountered during drilling, with the aim of maximising the level of understanding of the petrography, hydrogeology and geomechanical conditions of the rock at 4,500m. The principal technical aims are to:  

  • characterise the permeability/impedance of the target zone;  
  • evaluate the spatial extent of fracture distribution and orientation in the target zone;  
  • characterise the flowing zones and evaluate the ‘far-field flow contribution’;  
  • use acquired data to generate models to understand the regional geothermal resource.  

You can find more detail about our well testing programme here.


The information obtained from the drilling and testing of the deep well will enable us to understand the characteristics of the target zone and the viability of the proposed development of the full-scale geothermal CHP plant at Eden. 

Heat supply to Eden Project 

The final step in this first phase of the project is the installation of a heat main from the geothermal site to the Eden Energy Centre. This will supply geothermal heat from the well to the facilities at Eden, providing a demonstration of the greenhouse gas savings.

In Phase Two of the project (a second well and a small combined heat and power plant) the CHP plant will continue to supply heat to Eden using the heat main, and will also produce power. 

Project delivery partners

Eden Project Limited, a wholly owned subsidiary of the Eden Trust, a registered charity in the UK.


EGS Energy Limited, a leading geothermal development and consultancy group with experience on commercial scale projects in Cornwall and around the world. The EGS Energy team have significant experience and expertise, having been part of the Hot Dry Rocks geothermal programme in Cornwall in the 1980s, the follow-on EU programme in Soultz-sous-Forêts, France and the subsequent commercial power generating projects in Landau and Insheim, Germany, among others worldwide.


Bestec (UK) Limited, which is affiliated with Bestec GmbH  based in Germany and the team has over 70 years of direct experience in the deep geothermal sector, both in the UK and internationally, including extensive experience of drilling deep wells in granite.


University of Exeter is a delivery partner providing research services to Eden Geothermal. The University of Exeter combines teaching excellence and high levels of student satisfaction with world class research at campuses in Exeter and Cornwall. It is a member of the Russell Group of leading research-intensive universities.



European Regional Development Fund

The ERDF has provided £13.4m under its Priority Axis 4: “Supporting the Shift Towards a Low Carbon Economy in All Sectors”. The investment comes under the categories:

  • ​Investment Priority 4a
    Promoting the production and distribution of energy derived from renewable resources.
  • Investment Priority 4f
    Promoting research and innovation in, and adoption of, low-carbon technologies



Cornwall Council​

Cornwall Council has provided £1.4m in support of both its economic development programme and its vision for a low carbon energy future, which aims to:

  • Reduce fuel poverty to 5%
  • Meet 100% of electricity demand from renewables
  • Retain 30% of energy spend in the Cornish economy
  • Develop 50% locally owned generation
  • Reduce fuel bills by 20%
  • Create 4000 green jobs
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Gravis Capital Management

Gravis Capital Management has contributed £5.5m to the project through GCP Infra. GCP Infra is a FTSE 250, closed ended investment fund traded on the LSE, which invests in UK infrastructure projects with long-term, public-sector backed revenues.

The fund is managed by Gravis Capital Management, an investment management firm with £3bn of AUM. It launched its first product, A UK-listed fund focused on proving debt for UK infrastructure projects, in 2010. Subsequently, it has launched five further funds, including two closed ended funds (a student accommodation REIT and another infrastructure debt fund) and three OEICs focused on listed infrastructure, clean energy and listed UK real estate investment trusts.

Gravis has 44 staff and is headquartered in Savile Row, London. Gravis is authorised and regulated in the UK by the Financial Conduct Authority.

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