Uchechukwu Nwaiwu

Increasing local energy access in developing countries, particularly in off-grid regions where mini-grids are often overloaded, remains a critically underexplored area in energy transition. These regions often face significant technical and economic challenges, such as low generation capacity, high energy costs, limited energy access, and heavy reliance on diesel fuels. This study explores capacity expansion by integrating small-scale geothermal energy into such a mini-grid system to enhance the local energy supply. Unlike commonly studied solar-wind hybrid systems, this study evaluates the largely untapped potential of decentralized small-scale geothermal energy in providing a clean, reliable baseload complement to the variable solar PV system at Eka Awoke, Ikwo, Ebonyi State, Nigeria, at a minimal cost. The linear programming (LP) model presents the first in-depth analysis of the integration of small-scale geothermal energy into an existing mini-grid in sub-Saharan Africa. It evaluates the energy system under four realistic demand scenarios: Baseline, suppressed demand, increased connection demand, and increased connections with eCooking demand scenarios. The results obtained show that the geothermal capacity increased by 21.21% and 77.71% for the increased connection and increased connection with eCooking, respectively, while it decreased by 37.7% for the suppressed demand scenario. These findings provide valuable insights for energy providers and policymakers seeking to decarbonize and design more capacity and cost-effective strategies for increasing local energy access in mini-grids.

Geothermal resource assessment is crucial for the rural electrification of Nigeria. A comprehensive set of criteria was used to appraise promising geothermal sites in Nigeria. The evaluation of the sites was performed using the multi-criteria decision analysis (MCDA) method and taking into account evidence of a wide range of criteria from a set of geological, geophysical, well log, environmental, remote sensing, and geochemical datasets to appraise promising geothermal sites and to add to the current debate on the needed criteria for geothermal development. To gather relevant data, various sources such as bottom-hole temperature (BHT) data from different boreholes and oil and gas wells, aeromagnetic maps, reduced-to-the-pole, magnetic, heat flow, seismic, and geothermal gradient data from aerogravity maps, Bouguer anomaly maps, earthquake epicenter maps, satellite images, and geological maps were obtained from the literature. A case study of the thirty-six states of Nigeria, including the federal capital territory, Abuja (FCT), was conducted to illustrate how these criteria would reveal the technical aspect of the geothermal energy situation. A model was developed to show that the application of a wide range of criteria to the six datasets identified and analyzed in this study reveals that the datasets complement each other and should not be used independently. It can be found from the overall suitability map that more than 20% of the study area is suitable for geothermal energy development. It can also be observed from the map that some of the promising sites in Nigeria may include but are not limited to Bauchi, FCT, Taraba, Ebonyi, Adamawa, Oyo, and Nasarawa states in Nigeria. The opportunities for the further application of the approach are discussed, including the use of the model to help policymakers decide where to invest in the future.