Techno-Economic Evaluation of a PV-Biomass-Diesel Hybrid Systems with Electric Heating and Thermal Heat Storage (TES) for Isolated Power Grids: Case Study; the 5 MW Mamfe Diesel Thermal Power Plant, Southwest Region of Cameroon

Diesel-based power generation remains the primary source of electricity supply in many isolated and weak-grid regions of Sub-Saharan Africa, including Mamfe in the southwest region of Cameroon. However, high fuel costs, logistical challenges, and environmental concerns necessitate the integration of renewable energy technologies. This study evaluates the technical and economic feasibility of retrofitting the existing Mamfe diesel thermal power plant with a hybrid energy system incorporating solar photovoltaic (PV), biomass generation, thermal energy storage (TES), and electric heaters. Hourly electrical load data were modelled in HOMER to represent both current demand and future projected demand using a load growth factor of 1.3. Component-level techno-economic parameters were defined based on regional cost data and HOMER default libraries. System optimization was carried out using a load-following dispatch strategy to minimize net present cost while meeting the electrical load reliably. Simulation results show that the optimized hybrid configuration reduces annual diesel fuel consumption by approximately, 35% compared to diesel standalone system. The hybrid system achieves a levelized cost of electricity of 0.30 USD/kWh, representing a 22% reduction relative to the diesel-only configuration (0.38 USD/kWh). The annual energy contribution of the hybrid system consists of approximately 38% solar PV, 27% biomass, and 35% diesel generation. The results demonstrate that integrating renewable energy and thermal storage into existing diesel power plants is a technically viable and economically attractive pathway for reducing fuel dependence, lowering electricity generation costs, and improving sustainability in remote power systems.