Feasibility of Fifth-Generation district heating and cooling using mine water in Belgium: A Multi-Site Techno-Economic assessment

• 5GDHC is recognized as a promising, challenging decarbonization solution. • Open operational, assessment questions on 5GDHC functionality are unexplored. • Focus on prosumer-centric and decentralized approaches of 5GDHC systems. • Connection of disused, abandoned coal mines with the 5GDHC methodological design. Decarbonizing heating and cooling remains a major challenge for a building stock still reliant on fossil fuels. Fifth-generation district heating and cooling (5GDHC) offers simultaneous heating and cooling at low temperatures with higher efficiencies. This paper presents the first techno-economic feasibility assessment of 5GDHC using mine water in Belgium, applied to three Walloon coal basins (Liège, Charleroi, Mons) under the Walloon Recovery Plan. We integrate technical simulations, financial modelling, and cartographic analysis to screen and size potential pilot sites. Results show that mine-water reservoirs could supply ∼ 1.69 TWh yr –1 of thermal energy region-wide, with site viability driven by demand density and match between demand and subsurface resource, renovation level, and governance model. Under balanced heating–cooling loads and adequate renovation, life cycle GHG emissions can be reduced by up to ∼ 50% versus conventional systems; however, subsurface data gaps, tariff structures, and fragmented responsibilities introduce non-trivial uncertainty. We formalize these as design risks and provide sensitivity bands for demand, COP, electricity price, and well placement, outlining customized 5GDHC–Geomine design rules for Belgian contexts. The findings operationalize the Geomine concept—linking flooded mines with 5GDHC—as a replicable pathway for urban decarbonization.