An approach for ranking abandoned mines by the efficient use of their geothermal potential

Abstract

Purpose. To develop an approach for ranking abandoned mines in terms of the efficiency of mine water heat recovery by geothermal systems through applying the set of basic criteria; they allow considering geological and mining conditions in first approximation and preliminary assessing the performance of the systems located on them. Methodology. The proposed approach includes the ranking of mines by five basic indicators usually available or easily calculated such as the conversion factor of heat pumps COP, energy balance, thermal capacity, profit of operation, and reduction of CO2 emissions. The energy balance introduced by the authors earlier is defined as the relation of thermal energy produced to the thermal equivalent of electricity required for operation. These indicators are integrated in the complex rank to compare the expected performance and generate the priority lists for industrial installations in mines. Findings. We ranked 27 abandoned coal mines in Donbas with available data by five indicators separately and the complex parameter defined through averaging their contributions. The top promising sites for open non-circulation, circulation, and closed loop systems in terms of efficient heat recovery were identified. These sites refer to mostly deep mines in the central part of Donbas with the enhanced geothermal gradient over 0.03 °C/m. Originality. Firstly, an approach to evaluate the geothermal potential and ranking the mines regarding the efficiency of thermal energy use based on existing and introduced performance indicators has been substantiated and validated for a group of abandoned mines. The developed technique allows-analyz and preliminary quantify the feasibility of geothermal installations of different design. Practical value. The proposed approach for ranking post-mining sites enables generating the priority lists with regard to recovery of low-grade energy from mine water, thus, identifying the geothermal potential and most promising sites for further detailed feasibility studies and operation of geothermal systems of various types.