An optimal and low-emission off-grid renewable hybrid energy system for the provision of low-cost residential electrification

This study investigates the techno-economic and environmental feasibility of a hybrid renewable energy system for the electrification of an off-grid rural community in Dagai, District Swabi, Pakistan. Despite the growing interest in hybrid renewable systems, limited research has been carried out on completely renewable systems, including biomass-integrated hybrid configurations tailored to local resource availability in this region. To address such a gap, this work proposes a novel integration of solar photovoltaic (SPV), hydropower (HP), biogas generator (BG), and battery energy storage system (BESS) to ensure a reliable, sustainable, and fossil-fuel-free energy supply. The system is modelled and optimized using HOMER Pro software by incorporating site-specific resource data, including an average solar irradiance of 5.31 kWh/m \(^2\) /day and biomass availability of 2.83 tons/day. The optimized configuration achieves a 100% renewable energy fraction, entirely eliminating dependence on conventional fossil fuels, thereby differentiating it from existing hybrid systems reported in the literature so far. The proposed system demonstrates strong economic viability with a cost of energy (COE) of \($0.0913\) /kWh, a net present cost (NPC) of \($198{,}043\) , and an initial capital cost of \(\119,504\) , with a relatively low annual operating cost of \(\6{,}075\) . The biogas generator consumes approximately 15 tons of biomass annually, ensuring efficient utilization of locally available organic resources. From an environmental perspective, the system exhibits exceptionally low emissions, including CO \(_2\) (2.36 kg/year), CO (0.248 kg/year), unburned hydrocarbons (0.0108 kg/year), particulate matter (0.00150 kg/year), NO \(_x\) (0.233 kg/year), and zero SO \(_2\) emissions, highlighting its superiority over conventional energy systems. The findings confirm that the proposed SPV–HP–BG–BESS hybrid system is not only economically competitive but also environmentally sustainable. In summary, this study presents a region-specific, fully renewable hybrid energy model integrated with biomass utilization, offering a practical and scalable approach to address energy poverty in the remote areas of Pakistan.