Feasibility analysis of using mine water from abandoned coal mines in Spain for heating and cooling of buildings

In 2017, renewable energy accounted for 19.5% of the total energy used for heating and cooling in the European Union. This paper analyses the technical and economic feasibility of using mine water from flooded underground coal mines in Spain to provide renewable thermal energy to buildings located in surrounding areas. High efficiency heat pump system is proposed to provide sustainable energy for district heating and cooling, leading to a reduction of greenhouse gas emissions to the atmosphere. The results obtained show that 20 MW of thermal energy is available for heat recovery from mine waters, compared to 4 MW of electrical power committed for pumping from inside the mines and heat pump consumption. The economic model that has been developed indicates that the feasibility of the geothermal plants depends on the amount of thermal energy demanded, the efficiency of the system and the distance from the abandoned mines to potential users. A mine water geothermal plant with 10 MW of power provides energy for about 1,700 households at a distance of 2 km with an investment cost of 3.25 M€. Regarding the reduction of CO2 emissions, the emission factor is reduced to 0.048 kgCO2 kWh−1 using this approach.