Analysis of the Geothermal Energy Potential of Deep Mining Operations in the Nigerian Basement Complex for Hybrid Power Applications

Deep mining operations intersect geothermal heat flows that represent an underutilised energy resource, and their potential to support hybrid renewable energy systems at remote Nigerian mining sites has not been evaluated. This study analyses the geothermal energy potential of deep mining operations in the Nigerian Basement Complex, focusing on operations in Zamfara and Plateau states that reach depths below 200 metres. Geothermal gradient was measured in four deep boreholes using a downhole temperature logging tool, and rock thermal conductivity was determined for core samples from each borehole. Heat flow density was calculated at each location. An engineering assessment of mine water geothermal heat pump technology for space cooling and electricity co-generation was conducted using the measured thermal parameters. Thermodynamic modelling was performed using Engineering Equation Solver software. Results indicate geothermal gradients of 28 to 38 degrees Celsius per kilometre in the studied basement complex locations, with heat flow densities of 55 to 75 milliwatts per square metre. Modelling demonstrates that a mine water geothermal heat pump system at the deepest studied operation could contribute 180 kilowatts of thermal energy for mine cooling, reducing ventilation cooling loads by an estimated 35 percent. Hybrid integration with on-site solar photovoltaic enhances overall renewable energy fraction to 62 percent. The study recommends pilot installation and monitoring at the most thermally favourable site. Keywords: geothermal energy, deep mining, Nigerian Basement Complex, hybrid power, mine cooling.