School of GeoSciences Research

Galleries to Calories (G2C)

Galleries to Calories demonstrates the use of legacy mine workings as recycled heat storage and transport networks.

The Galleries 2 Calories project logo, reads "G2C" in red and blue text

Galleries to Calories (G2C), comprising industry, academic and national research partners from Scotland, USA and Ireland, demonstrates for the first time the use of legacy mine workings as recycled heat storage and transport networks to provide managed sustainable regional recharge of low enthalpy (< 40°C) geothermal heat present naturally in the subsurface, to make it available for regional heat pump extraction. G2C demonstrates the storage, transport, and recycling of waste industrial heat in extensive legacy mine workings southeast of Edinburgh, Scotland, and assesses its potential application in European and US coal and mineral mines. 

A primary aim of G2C is to install a field test site where the hydraulic and heat transport characteristics of the legacy mine workings can be investigated in detail through the provision of both an injection and extraction borehole at two different locations within the mine workings, and the establishment of a demonstration of the technology. The project design is based around the need to provide a working prototype of up to 9 MW of cooling for a national computer facility. The heat geobattery concept is that the cooling is provided using mine water in a closed loop heat exchanger at the surface, and an open loop heat exchange in the mine workings. Once this heat is distributed and stored in the subsurface, various heat pump technologies in different surface geographical locations can be employed to recover it. The recycled heat will augment the natural geothermal heat present and sustainably replenish the natural heat extracted through the heat mining using heat pump technology.


You can find out more information about the project from the Galleries to Calories project blog.


Diagram summarising the G2C concept and showing heat transport through the mine
The generic heat geobattery concept of recycling excess heat from cooling demand and using legacy mine workings to store and transport the heat to users down gradient.

G2C undertakes a full feasibility study of heat injection and subsurface transport, including in-depth geological, hydrogeological and geochemical site characterisation, quantitative assessment of the dynamic processes initiated by the widespread temperature changes to the subsurface, assessment of the sustainable thermal resource management for different development scenarios, determination of the best techniques for monitoring heat distribution, development of socially based economic models, investigation into the legal aspects of subsurface heat ownership as a basis for facilitating the establishment of equitable and sustainable business models and technical consideration of its wider application to European and US coal and mineral mines.

Project targets

1. Demonstrate the feasibility of the heat geobattery concept as a low-carbon, resilient, commercially viable, and environmentally acceptable method of creating a regional circular heat economy.
Our project will provide storage of waste and harvested heat, heat extraction through heat pump technology and subsurface heat transport over kilometre-length scales under the urban environment using the hydraulically connected legacy mine workings.
2. Demonstrate the viability of the withdrawal of fluid and injection of 9 MW into regionally connected mine workings.
Focussing on the cooling/coolth requirement of the ACF.
3. Create a regional hydrogeological, thermal, mechanical, biological and geochemical model of the heat geobattery exemplar site.
Reducing uncertainty in subsurface flow and heat transport, evaluating potential geochemical impacts and ensuring due diligence with respect to environmental impact. 
4. Construct two injection/extraction boreholes targeting the mine workings and a monitoring borehole within the workings.
The boreholes will access different seams within the same workings to be used for field testing to characterise the hydraulic, thermal, biological and chemical response of workings.  

5. Identify source-pathway-receptor combinations for future risk assessment.

For instance, through acid mine water drainage leading to environmental impact.

6. Augment the established monitoring networks of the Coal Authority and the Scottish Environmental Protection Agency.

G2C will integrate a number of telemetrical real-time monitoring devices for water quality, micro-seismic detection, surface deformation measurements and the use of drones for large scale ground deformation and temperature mapping.  

7. Use numerical modelling techniques to simulate non-isothermal fluid flow, tracer and heat transport and distribution through the system.

This will include identification of preferential flow paths, tied into the source-pathway-receptor assessment, and the prediction of measurable geophysical monitoring thresholds, thereby identifying geophysical techniques to determine the spatial extent and rate of transport of heat.

8. Investigate the social and economic assessment framework necessary in order to ensure that the risks/benefits are understood.

This will facilitate successful engagement with local communities undertaking the changes necessary to implement the emerging technologies.  

9. Establish best practice methods for determining heat ownership.

This will form the basis for viable economic and commercial models for the supply, storage, and use of the heat. 

10. Ensure knowledge exchange in the form of a best practice-style publication.

This will facilitate the development of the technology under established planning, permitting, and legislation. 

11. Establish a field site for future generations’ training in hydrogeology, heat storage and heat extraction technology in urban environments.

This will include its use for training students in different engineering and hydrogeological disciplines at BSc, MSc, and PhD level, and also enable training for technical installation staff for low-enthalpy (40°C) heating & cooling technology. 

12. Investigate the potential of the heat geobattery concept for other mine sites.

This is including selected coal and mineral mines of Europe, and the world-class Zn-Pb Irish mines, in particular.

Proposed location

G2C mine plans implemented into numerical model
Galleries to Calories demonstrates the use of legacy mine workings as recycled heat storage and transport networks.

Project partners

Graphic displaying the logos of the Galleries 2 Calories partner organisations
Galleries to Calories comprises industry, academic and national research partners from Scotland, USA and Ireland.


Additional information about Galleries to Calories may be obtained by contacting:  

Prof Christopher McDermott    Personal Chair of Hydrogeology and Coupled Process Modelling

Mr Ben Morse    Manager of Teaching-related Industrial Engagement and Strategic Relations

  • Email:
  • Address: School of GeoSciences, University of Edinburgh, ECCI, High School Yards, Edinburgh, EH1 1LZ