Comprehensive Assessment of Soybean Biodiesel Environmental and Combustion Characteristics

The study presents a comprehensive life-cycle assessment of soybean-based biodiesel compared with conventional diesel fuel, focusing on carbon footprint, physicochemical properties, and combustion emissions. Experimental transesterification was carried out in a microwave reactor at 65°C for 90 minutes, yielding biodiesel with a density of 877 kg/m³ and a viscosity of 4.65 mm²/s. Combustion tests revealed lower hydrocarbon (13 ppm) and carbon monoxide (0.023%) emissions with biodiesel, whereas nitrogen oxides were slightly higher at 410 ppm than with diesel. Life cycle analysis indicated that soybean biodiesel had a total carbon footprint of 106.2 g CO₂-eq/MJ, approximately 13.5% lower than diesel fuel (122.8 g CO₂-eq/MJ). The main contributors to emissions were cultivation and fuel combustion. Despite the relatively modest reduction in greenhouse gas emissions, the research confirms the potential of soybean biodiesel as a partial decarbonization strategy in the transport sector. The findings highlight the necessity of full-cycle accounting to estimate climate impacts and optimise production processes realistically.