Global Knowledge Exchange - Experiences and Outputs From The Iea Geothermal Mine Water Energy Expert Group

Net-Zero carbon emissions targets require significant progress to be made in the decarbonisation of heat, and many Governments have defined their ambitions to transform heating of homes to clean energy sources. Seen as a global leader in terms of Net Zero Strategy, the UK strategy sets out that key decisions on the decarbonisation of heat are to be made by 2026. The Heat and Buildings strategy indicates geothermal energy could be part of the solution to diversify the low carbon alternatives to fossil fuel heating, despite the low temperature resource available in countries like the UK. At the same time, legacy from a previous era of high-carbon heating still exists in many countries in the form of abandoned coal mines. Upon closure and with the cessation of dewatering, the mines have become naturally flooded with groundwater which contains a vast low temperature energy resource for heating and cooling, and thermal energy storage. The energy resource can be abstracted through schemes that pump groundwater from the mines via boreholes, and once passed through a heat exchange/heat pump arrangement, can provide space heating and cooling for homes and businesses, before returning the water within a sealed loop to a different part of the mine system. Low temperature shallow geothermal heat recovery and seasonal thermal storage in abandoned coal mines thus offer a sustainable energy opportunity in various countries around the world. Small numbers of successfully-operating mine water geothermal and heat storage schemes have proved the concept of using this energy source for heating and cooling of buildings. However, the very large resource potential has yet to be widely accessed. Economics, regulation, policy making, awareness and social acceptance have been identified as barriers to widespread utilisation, as well as appropriate management of technical and environmental risks. Such barriers can be overcome more quickly through knowledge exchange, scientific evidence and collaboration. The IEA Geothermal Technology Collaboration Programme has set up an international working group on mine energy within Working Group 14, starting in March 2022 and open to all interested in mine water thermal energy. The rationale for setting up this group is to use the UK’s growing industry, academic and regulatory expertise and current interest to leverage global collaborations in the field of mine energy. Following international symposia on mine water energy in 2021 and 2022, topics of interest have been identified: a repository of case studies of successes and failures, gathering best practice workflows, and documenting regulation and policy in different countries. According to recommendations for developing mine water energy set out in a White Paper published in July 2021 that highlighted cost and risk as some of the biggest barriers, it is hoped the outcome of these studies will encourage further deployment of the technology. The aim of the paper is to encourage participation in the working group and present initial findings. We will summarise global and UK implementation of mine water geothermal in 2022, share the methods used to develop this international task on mine energy, and present the initial outputs gathered.