Transforming geothermal hazards in mines into sustainable power generation for energy conservation and thermal environment management

The high geothermal temperatures in deep mines pose significant operational challenges by creating severe underground heat hazards. Converting this geothermal energy into a useable resource represents a critical pathway to mitigating these adverse conditions. This paper introduces a paradigm shift through an innovative geothermal sustainable power generation and energy storage system (GTPS) tunnel, which integrates thermal regulation with geothermal energy storage and power generation. This dual-purpose strategy enables the in-situ conversion of geothermal energy into readily accessible power resource, simultaneously harnessing a natural resource while controlling the underground thermal environment to reduce heat hazards. To evaluate the feasibility of this concept, a multi-physics numerical model was developed, integrating dynamic heat transfer from the surrounding rock, non-isothermal airflow, and thermoelectric conversion. Results show that the GTPS tunnel can generate substantial electricity under a significant temperature difference between the airflow and the surrounding rock, while also reducing wall heat flux compared to conventional tunnels. In contrast to an insulated tunnel (IT), the GTPS system provides active airflow temperature regulation by absorbing heat when airflow temperatures are high. Under conditions of an initial rock temperature of 50 °C and an airflow temperature of 15 °C, the system achieved a peak power density of 4.53 W/m2, stabilizing at 1.20 W/m2 after prolonged ventilation. The power output increases linearly with the rock-air temperature difference. Heat sinks attached to the thermoelectric modules (TEMs) play a vital role in enhancing output by enlarging the temperature gradient across the modules. Furthermore, power output follows a negative exponential growth function with respect to the Seebeck coefficient of the TEMs, indicating that performance gains diminish as the coefficient increases. This study presents a viable approach for the utilization of geothermal energy in mining, contributing to both energy sustainability and improved thermal management in deep mining.