GeoCubed selects RSE (Ross-shire Engineering) to Provide EPCC Support for The United Downs Pilot Plant and Deep Geothermal Assay Results Confirm Expected Lithium Concentrations

11th Januray 2022

GeoCubed, the joint venture between Cornish Lithium Limited (“Cornish Lithium”) and Geothermal Engineering Limited (“GEL”), is pleased to announce that RSE (Ross-shire Engineering) Ltd. (“RSE”) has been selected to provide engineering, procurement, construction and commissioning (“EPCC”) support for GeoCubed’s Pilot Plant (the “Pilot Plant”). The Pilot Plant is due to be commissioned at United Downs in Cornwall by the end of March 2022.

The £4.0 million Pilot Plant is being supported by the Cornwall and Isles of Scilly Local Enterprise Partnership (“LEP”) with £2.9 million from the UK Government’s Getting Building Fund.

GeoCubed have appointed RSE due to their previous experience in supporting the development of innovative new technology from pilot plants through to commercialisation along with the fact that they are a full-service contractor, able to deliver the majority of the requirements of the Pilot Plant in-house. Their timely support will be invaluable in designing and integrating the Direct Lithium Extraction (“DLE”) technology module, provided by GeoLith, into an operational plant.

Deep Geothermal Waters Results

In August 2021 Cornish Lithium and GeoCubed worked together to collect a bulk sample of geothermal water during the Electrical Submersible Pump test conducted by Geothermal Engineering Limited (“GEL”) at its United Downs Deep Geothermal Project (“UDDGP”). The fluid collected will primarily be used to feed the Pilot Plant for the purposes of evaluating DLE technologies.

Lithium concentrations averaged 263 mg/l over 63-hours of pumping, with a maximum grade of 296 mg/l recorded. These concentrations were in line with those obtained from an airlift test in August 2020.

In addition to the encouraging lithium concentrations, other key by-products such as caesium, rubidium and potassium were shown to be at elevated levels. Importantly deleterious elements, which can negatively impact the processing of waters through DLE technologies and the quality of the final lithium product, were exceptionally low. Magnesium levels were below 5 mg/l, transition metals such as iron were shown to be negligible, and silicon concentrations were low.

DLE Technology Module

GeoCubed is also pleased to announce that the DLE technology module, provided by GeoLith, has now arrived at RSE’s site in Darlington, UK and RSE are now integrating the DLE module into the Pilot Plant ahead of its delivery to the United Downs Geothermal Testing Facility, where the Pilot Plant will be commissioned by the end of March 2022.

Jeremy Wrathall, CEO and Founder of Cornish Lithium and a Director of GeoCubed, said: “We are pleased to announce the appointment of RSE as EPCC contractor. The GeoCubed team has established a strong relationship with the team at RSE and we look forward to working with them to successfully deliver this Pilot Plant, which will provide vital operational data to inform and enable the construction of a commercial scale plant. This will place Cornwall at the forefront of lithium production, as the UK strives to secure a domestic supply of this critical battery metal.

“It was also reassuring to see that the assay results from the Deep Geothermal Water samples confirmed the lithium concentrations observed in earlier test work. The continued low levels of deleterious elements is also good news and will be beneficial as we utilise the Pilot Plant to establish the most appropriate processing technologies for Cornish geothermal waters.”

Ryan Law, MD and Founder of GEL and a Director of GeoCubed, said: “This is another step forward towards the establishment of geothermal lithium extraction in Cornwall.  We look forward to seeing the results of this next stage of the project as we move forward towards full scale, commercial Direct Lithium Extraction.”

Mark Duddridge, Chair of the Cornwall and Isles of Scilly LEP, said: “We share the ambition for Cornwall to lead the domestic production of lithium as part of the UK’s energy transition. The LEP has committed £2.9 million of Getting Building Fund investment towards the Pilot Plant and we look forward to seeing it commissioned in the next few months.”

Mark Livingston RSE Director of Products, Technology and Modular Solutions said: “RSE are really excited by the opportunity to continue our collaborative working relationship with the GeoCubed team in the next development stage of this new innovative lithium production process. We pride ourselves in being a business at the forefront of embracing new technologies which support the sustainable and secure growth of the UK economy.”

Notes to Editors

About GeoCubed

GeoCubed is a collaboration between Cornish Lithium and GEL, the developer of the United Downs Geothermal Power Project, established to design, procure and build a pilot plant to trial Direct Lithium Extraction (”DLE”) technology to extract lithium from the geothermal waters, which circulate naturally at depth in the granite rock that underlies Cornwall. This £4 million project will be part-funded by the UK Government’s Getting Building Fund.

For more information about GeoCubed, visit

About Cornish Lithium

Cornish Lithium is a highly innovative mineral exploration and development company focused on the environmentally-sustainable extraction of lithium from geothermal waters and hard rock in the historic mining district of Cornwall. The Company has secured agreements with the owners of mineral rights over a large area of the County and is using modern technology to re-evaluate the region for its potential to produce lithium and other vital technology metals in a low carbon and low impact manner. A secure domestic supply of such metals is considered vital to the industrial strategy of the UK, as it moves towards Net Zero 2050 and the production of electric vehicles.

For more information about Cornish Lithium, visit

About GEL

GEL was founded in 2008 and is currently developing the first deep geothermal power plant in the UK, a £28 million project at the United Downs site in Cornwall. Two deep geothermal wells were successfully drilled in 2019. The project concepts are of European significance and there are currently 27 universities across Europe linked to it. The production well is the deepest, hottest well ever drilled in the UK, at 5.275 kilometres. The Company has recently proved that the geothermal reservoir it has developed at United Downs will support power production.  The power plant is expected to come online in late 2022.

About RSE

RSE is an engineering group that specialises in the Design, Build and Maintenance of Water Treatment and Water Recycling Equipment along with specialist Technology integration.  The company has become a market leader in time, cost and carbon efficient modular solutions across various sectors. Its 1,000 + staff are skilled in the design, engineering and delivery of MEICA projects and services (MEICA: Mechanical, Electrical, Instrumentation, Controls & Automation).

About the Getting Building Fund

On 4 August 2020, the UK Government confirmed the list of more than 300 successful projects that will receive a share of £900 million from the Getting Building Fund.  The full list of projects is available on GOV.UK.

The Getting Building Fund is investing in shovel-ready infrastructure projects to create jobs and support economic recovery across the country. Projects funded include:

  • regeneration of town and city centres
  • green infrastructure and clean energy
  • transport and digital connectivity improvements
  • unlocking of housing and business sites
  • support for SMEs and learners.

The successful projects are expected to deliver up to 85,000 jobs, over 1,500,000 square metres of commercial floor space, unlocking 45,000 homes, almost 1,000,000 square metres of public realm or green space improved or created, over 50,000 new learners assisted, and 65 million kilogrammes of CO2 emissions saved.

All projects have been selected by Local Enterprise Partnerships and Mayoral Combined Authorities in each area and endorsed by the Housing Secretary.

For further information about GeoCubed, please contact Jilly Easterby at Curlew PR;; 07743 164434.

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