The potential of agricultural and livestock wastes as a source of biogas in Vietnam: Energetic, economic and environmental evaluation

Many economies, including Vietnam, have substantial potential for producing energy from agricultural waste. However, the analysis of using agricultural waste as a renewable energy source and its associated economic and environmental benefits remain unclear. This study aims to a) estimate trends in greenhouse gas (GHG) emissions from livestock and crop residue burning; b) evaluate the environmental benefits of using biogas in substitution for coal, wood, and liquefied petroleum gas (LPG) under various scenarios; c) assess the economic viability of a household-scale biodigester, and d) propose recommendations for the effective exploitation and utilization of biogas. GHG emissions were calculated for livestock and crop residue burning (CRB) using activity data and emission factors. The environmental analysis was conducted to understand the role of biogas in reducing GHG by assuming 100 % exportation of biogas in substitution for fuels for electricity and heat generation. The economic benefits were assessed through internal rate of return (IRR), net present value (NPV), payback period, levelized cost of electricity (LCOE), and levelized cost of heat (LCOH). Results indicate that, between 2000 and 2050, CO2-eq emissions will rise from 38.5 to 95.2 Mt. Environmental analysis shows that replacing coal or wood with biogas can bring more benefits than LPG, in reducing GHG emissions by 68.2 and 67.9 Mt CO2-eq in 2020 and by 148.4 and 147.9 Mt CO2-eq by 2050. Economic analysis shows that investment in biodigesters is most viable when replacing LPG with biogas, with NPV = $4878, IRR = 57.2 %, PBP (simple) = 1.7 years, and LCOH = $0.029/kWh.