Assessment of GHG emission reduction potential of an integrated community solar and biogas renewable energy system: a case study of Hakwata Green Village in Zimbabwe

Abstract Purpose This study analyses the greenhouse gas (GHG) emission impact of a combined community solar and biogas energy system, using the Hakwata Green Village in Zimbabwe as a case study. The primary aim is to evaluate the Global Warming Potential (GWP) reduction for carbon finance achieved by a 200 kWp/915 kWh solar mini-grid and a 540 m³ biogas plant serving over 12 500 people, relative to default alternatives (grid extension for solar; firewood for biogas). Methods A comprehensive Life Cycle Assessment (LCA) was conducted using SimaPro with the ReCiPe 2016 method, focusing on GWP as the key climate change driver and role in carbon finance. The study employs a dual functional unit system: kWh of electricity delivered from the solar mini grid and MJ of energy delivered from the biogas system over the project’s 20-year life. Avoided emissions were calculated from the replacement of national grid with solar, firewood with biogas and the replacement of synthetic fertiliser with biogas digestate. Results and discussion The solar PV system exhibits a life-cycle emission intensity of 145 g CO₂ eq kWh⁻¹, an 85% reduction compared to the Southern African Power Pool grid (SAPP) mix (980 g CO₂ eq kWh⁻¹). The biogas system, despite construction phase emissions, achieves a net negative carbon balance of 26,851.90 t CO₂ eq over 20 years once avoided firewood and synthetic fertiliser burdens are credited. When the two subsystems are combined and compared with the baseline, the integrated community energy system reduces GWP by 1,614 t CO₂ eq year⁻¹, yielding a cumulative net reduction of 33,408 t CO₂ eq over the 20-year project life. Conclusions The findings confirm that an integrated solar-biogas community energy system can deliver emission reductions of 8% against grid electricity and 9% against firewood, while avoiding 33,408 t CO₂ eq over 20 years. These verified reductions, combined with improved energy access, make such projects are strong candidates for carbon finance, offering a replicable rural electrification model beyond the Hakwata Green Village case.