Deep geothermal heating system in Cornwall
Overview
The Eden Project has embarked on a geothermal energy initiative that promises to significantly advance its sustainability goals. Partnering with EGS Energy and Bestec UK, the Eden Project has formed Eden Geothermal Ltd to tap into the Earth's natural heat, utilizing the granite beneath its site. This innovative project involves drilling a 5.3km deep well into the rock, creating a geothermal plant that will supply heat to the iconic Rainforest and Mediterranean Biomes, as well as a new state-of-the-art plant nursery called Growing Point.
The Eden Geothermal Project marks a significant step towards the Eden Project's ambition to become a net-zero and climate-positive organization by 2030. The geothermal plant will not only replace fossil fuels used for heating but also provide valuable data for future geothermal projects in Cornwall. The project's research, conducted in collaboration with the University of Exeter, aims to enhance understanding of deep geothermal resources and geology, potentially unlocking further geothermal development in the region.
Technical details
The geothermal system uses a vacuum insulated tube (VIT) inserted to a depth of 4,000 meters. Hot water is pumped to the surface using a submersible pump and passes through a heat exchanger, delivering heat at 85°C. The cooled water is then recirculated to be reheated, in a continuous coaxial system. This £22 million project has been made possible through funding from the European Union, Cornwall Council, and Gravis Capital Management.
Drilling of the UK's deepest geothermal well, EG-1, began in May 2021 and reached completion in October of the same year. The well extends to a vertical depth of 4,871 meters, with a total length of 5,277 meters, employing conventional rotary drilling with muds. Following the successful drilling, a series of well tests were conducted to assess the hydrogeological characteristics of the target rock zone. These tests, designed in collaboration with the University of Exeter, focused on understanding the permeability, fracture distribution, and geomechanical conditions at depth.
The implementation of a single well heat exchanger and a 3.8km heat main has been a critical component of the project. This system links the geothermal site with the Eden Project's heat loads, ensuring efficient heat distribution. The heat main consists of two steel pipes, heavily insulated, that transport hot water to and from the geothermal plant. At the Eden Energy Centre, plate heat exchangers extract the heat for use in Eden's heating circuits.
Summary
Depth: 5.3km
Temperature: 85°C
Investments: £22 million