Thermal energy recovery from abandoned mines

Underground thermal energy storage (UTES) is a technology that has been widely adopted in Europe, but has limited uptake in the UK. Most of the schemes are located in sandy aquifers in the Netherlands and, subsequently, the algorithms used in UTES calculations do not reflect the geology and hydrogeology of the UK’s hard-rock aquifers.

Funding from the Natural Environment Research Council (NERC) has enabled BGS to undertake new research at the UK Geoenergy Observatories (UKGEOS) in Cheshire and Glasgow. Project Thermal Recoverywill conduct experiments related to the efficiency of UTES, with the initial fieldwork phase already underway alongside parallel work developing a new calculator tool. The proposed calculator tool is being designed to assist in the feasibility planning stage for both mine thermal energy storage and borehole thermal energy storage schemes.

The experiments being conducted at the Glasgow Observatory are investigating how UTES efficiency is influenced by the storage period and repeated storage events, utilising both the Glasgow Upper and the Glasgow Main workings with heat injection alternating between the two mines. A range of storage durations, from 24 hours to 21 days, will be tested to simulate different demand scenarios. (Longer, interseasonal storage will not be tested in this project due to time constraints.)

Distributed temperature sensing (DTS), electrical resistivity tomography (ERT) and groundwater logger data from the mine-workings boreholes will be analysed to determine any changes in temperature in the mines and gain an understanding of the thermal plume movement and recovery efficiencies. This data will be fed into the development of the calculator tool.

This research is an exciting opportunity to increase the understanding of thermal energy storage and how this technology can be applied to the geology around the UK.

Vanessa Starcher, science and operations lead for the Glasgow Observatory.

At the Cheshire Observatory, the thermal storage properties of the Sherwood Sandstone aquifer are being profiled using active (heated) DTS and ERT.  Heat loss is evaluated as a function of the geology and groundwater flow velocity to understand the main heat loss pathways and how schemes can be designed to maximise storage efficiency.  The field data will be used to simulate the behaviour of model UTES installed at different depths with varying well geometry and hydraulic gradients.

These experiments are expected to be complete in early January 2027 and the data generated will be provided to the research community on an open-access basis, alongside an accompanying data report. The calculator tool will allow the idealised storage behaviour of both the Glasgow and Cheshire observatories’ geology to be compared to actual results from field testing, and identify features that influence storage performance.

For those interested in the data or finding out more about Project Thermal Recovery, there will be opportunities to discuss the project and final calculator tool in the New Year. In the interim, interested parties can contact UKGEOS enquiries (ukgeosenquiries@bgs.ac.uk) to find out more about the project.