Many urban areas are underlain by abandoned mine workings that offer the potential for exploitation using heat pumps to provide space heating and cooling. This is achieved either by using existing shafts or drilling boreholes to intercept workings. The process of coal extraction enhances the permeability of the subsurface, which provides pathways through which water can flow. When mines are abandoned, pumping to dewater the workings ceases and groundwater rebounds, flooding the workings. Shafts and tunnels may remain open and provide major pathways for groundwater flow. This offers a resource that is generally warmer than the near surface and typically around 15°>C at depths of around 200 m below surface.
BGS has created a detailed three dimensional model of the geology beneath Glasgow that incorporates old mine plans and the locations of shafts and access tunnels. Such detailed models are necessary when planning exploitation of the mine waters to optimise system design. Initial calculations have revealed that mine waters present beneath Glasgow have the potential to provide up to 40 per cent of Glasgow's heating requirements with the potential for cooling during summer months.
Clearly the UK's legacy of abandoned mine workings offers a huge potential resource, much of which is located beneath major towns and cities. BritGeothermal intends to continue this research and promote the potential of this low carbon resource.