The Thermal Resource of Mine Waters in Abandoned Coalfields; Opportunities and Challenges for the United Kingdom

Abstract

In the absence of high temperature hydrothermal zones, the most promising geothermal opportunity in the United Kingdom (UK) is direct use of low enthalpy resources. In order to advance understanding and knowledge of direct use the UK participates in Working Group VIII, “Direct Use of Geothermal Energy”, a collaborative task of the International Energy Agency Geothermal Technical Cooperation Programme (IEA Geothermal). The working group advances direct use knowledge through workshops and publications of good practice and case histories. This review paper contributes to this objective with a discussion on the geothermal potential of the heat contained within the waters of disused mines, which has particular relevance to the UK. It may come as a surprise that mine waters from abandoned coal mines represent a large geothermal resource and offer a number of advantages for direct use geothermal. Coal mining has created enhanced permeability in rocks of usually low permeability making available a large body of readily accessible groundwater. In some cases convection within the mine water network will allow warmer water to rise from depth to the near surface. In the UK, coal mining often resulted in the establishment of urban areas creating a ready market for this low grade geothermal heat. This legacy from hundreds of years of coal mining is just starting to be developed, but there are barriers to be overcome. This paper discusses, from a UK perspective, the opportunity presented by mine waters, the extent of the resource, legislative issues and the advantages and disadvantages of mine water geothermal systems.