Extracting Energy from Flooded Coal Mines for Heating and Air-Conditioning of Buildings: Opportunities and Challenges

Extraction energy from flooded coal mines for heating and/or air-conditioning applications could provide a low-carbon and sustainable technology for the future. In heating applications, the implementation normally utilises heat pump technologies to upgrade the temperature of water from a nominal value of normally about 12 to 20 °C to a level above 45 °C. For cooling applications, the water could be used directly or via a heating pump for the cooling process, depending on the temperature of the water. This paper outlines two case studies implemented in the UK at Caphouse Colliery and Markham Colliery. The paper highlights the opportunities and challenges of the technology; it compares between the two systems in terms of configuration, water quality and the need for maintenance. The paper also outlines the commercialisation aspect of the technology and the potential challenges and opportunities captured via a technical workshop and an online survey. The paper also discusses the geohazard prospective of coal mines when used for extracting the thermal energy. The results show that extracting energy from flooded coal mines is unlikely to create any significant geohazard risk, but has the benefits to develop and regenerate the former coal mining areas. The technology can be used to provide low-carbon sustainable energy to homes and businesses in the UK towards zero-carbon future. However, more effort is needed to enhance public awareness and encourage future investments to allow the technology to be utilised in new and existing residential and commercial buildings.