The UDDGP project is the first geothermal power plant in the UK. It is funded by a mixture of public and private funds to include the European Regional Development Fund, Cornwall Council and Thrive Renewables plc. The aim of the project is to produce power and heat from the hot granite rocks beneath Cornwall at the United Downs Industrial Site near Redruth. Two deep, directional wells have successfully been drilled; the production well to a depth of 5275m and the injection well to 2393m. Both wells have intersected the target Porthtowan Fault Zone located approximately 800m to the west of the site.

Project timeline

2009: Concept
The heat generated from the earth is far greater than that required by the world’s population. It is also constant and can therefore produce clean renewable power and heat regardless of the weather conditions at surface.

2010: UD Site Acquisition & Planning
The site was selected for the excellent geology, road access for the drilling rig, the connection to the grid and for being within an industrial landscape.

2012 - 2016: Secure Funding
It took 5 years to secure appropriate funding for the project from a combination of the European Regional Development Fund, Cornwall Council & Private Investors.

2017: Funding Agreements Signed
The project is expected to cost in the region of £30m.

2018: Procurement & Drilling
All contracts were Tendered and awarded using European guidelines to ensure that they were awarded fairly and transparently.

2019: Two Geothermal Wells Completed
The Innovarig used 38 drill bits to drill the wells. The production well is the deepest on UK soil at 5275m and the injection well is 2393m deep.

2020: Final Testing & Power Plant Order
A smaller rig was used to complete the wellhead and enable test equipment to be used to take core samples, temperature and flow test.

2021: Power Plant Commissioned
A ‘Binary’ power plant will be used. This means that there are no ‘plumes’ of vapour and very little to see on the surface when the plant is finished.

TECHNICAL

Drilling rig
The Innovarig is a new generation semi-automatic hydraulic rig constructed in 2007 by Herrenknecht vertical GmbH. It is the quietest rig of its size in Europe. Specifically designed for use in urban and noise sensitive areas.

Innovarig Technical Details: Height 51.8m, Maximum hook load 418 tonnes, Top drive 4,100 kN, Maximum trip speed 500 m/h, Drill pipe size 5 ½”.

Drill bits and casing spec
The drill bits were steel tri-cone with tungsten carbide inserts, Four sizes were used for the production well and three for the injection well. The wells are steel cased for most of their length with just the deepest section open to allow water to circulate.

Chipping analysis
All metals and minerals ever mined were found in this zone, these include metals being explored today such as wolframite (tungsten ore) and cassiterite (tin ore).

Binary power plant
The geothermal brine will not be fed directly into the turbine. Instead, the very hot brine passes through a heat exchanger to heat a secondary fluid that expands to drive the turbine (like steam) and is then condensed into a fluid again. The two circuits (geothermal and binary fluid) operate 24/7.

Community
GEL takes its responsibility to the local community very seriously and has ensured that the project is as transparent and engaging as possible. Many public Drop-In sessions and private group visits and talks have been hosted. Community groups receive regular visits and the project team have attended a variety of village and county shows. A community fund managed by Cornwall Community Foundation was set up by GEL with £40k to be awarded to local groups and projects.