Methodology and modelling approaches for assessing the potential of flooded abandoned mines to be used for production and storage of geothermal energy to feed Heating-Cooling Networks – example of the Liège case study in Belgium

Mines are usually flooded with large volumes of water after abandonment making them a hydrogeological and geothermal asset. At locations where urban areas developed directly above or near these abandoned mines, their coupling with new generation of heating and cooling networks matches perfectly. These mines can indeed be used as a primary energy source of heat or cold or as a medium for storing the excess thermal energy coming from these networks. The methodology for assessing the thermal potential of these abandoned mines and its adequation with the surface thermal energy demand and potential customers is presented here using as an example the case study of a potential site located in Liège, Belgium. The approaches used for mine network characterization and for thermal-hydraulic ‘TH’ modeling are discussed. For the latter, fast 1D pipe network and fully physical 3D TH modeling approaches are explored. These approaches allow to understand the role of the different features of the mine system (galleries, shaft, panels and surrounding high permeable and low permeable rock) and are essential for defining well locations and forecasting long term thermal performance of the system. Finally, the main challenges to consider when studying and developing these thermal systems are presented and analyzed.