The Future Perspective: Geothermal Energy in Nigeria – An Option to be Explored

Abstract As the transition towards a green energy future intensifies, cleaner energy sources are expected to drive the decline in the demand for fossil fuels. This creates room for renewable energy sources such as geothermal. Geothermal energy is generated from the earth's crust which is transported through cracks and fractures in the host rocks and its natural fluids at temperatures above the ambient level. The rate of heat flow in the crust is estimated to be 59Mw/m2 [1.9*10-2 Btu/h/ft2]. In mature continental cratons, the geothermal gradient can be as low as 10 °C per kilometer. However, in active volcanic areas, it can exceed 100 °C per kilometer. A typical geothermal gradient of 25 °C km− 1 gives a conductive heat flux of 60 mWm− 2 for electricity generation. Considering the Nigerian basement complex, the estimated geothermal gradient of Borno and Sokoto States, both located in the Northern region are 1.1 to 5.9°C/100m with a heat flow of 8.9 to 117.8mW/m-2 and 0.9 to 7.6°C/100m with a geothermal heat flow of 52.11 to 130.28mWm-2 respectively. In addition, in eastern Nigeria, Anambra State, the estimated geothermal gradient is 2.5 to 4.9°C/100m with a heat flow of 64.4 to 97.3 mWm-2. Geothermal energy has the potential to improve Nigeria's current poor energy dynamic. Enhanced Geothermal System would exploit heat energy that is trapped in the subsurface host rock by creating an open system of connected fractures along which water can flow down the injection wells and get heated through contact with the rocks. This is then recovered to the surface in production wells to form a closed loop. The idea is an extrapolation that emulates a hydrothermal circulation system – which produces electricity that can be applied commercially.