Life cycle assessment of biodiesel production from selected second-generation feedstocks

Abstract

Biodiesel has the potential to substitute conventional diesel and reduce global transport-related greenhouse gas emissions. In this study, the environmental impacts of biodiesel production from three East African second-generation feedstocks: Castor (Ricinus Communis), Croton Megalocarpus, and Jatropha, were assessed in comparison with petroleum-diesel. Inventory data analyzed was obtained from primary and secondary sources in Uganda and existing literature. Life Cycle Assessment methodology was applied in accordance with ISO 14040. Reductions in global warming and human toxicity potentials of up to 7% for B10 biodiesel blends relative to imported petroleum diesel were obtained. Similar reductions were obtained for the other assessed mid-point impact categories. Though relatively very low in absolute terms, this reduction rate is in sync with the target annual reductions of 7.6% and 2.7% required to meet the Paris Agreement temperature targets of 1.5 °C and 2 °C respectively. Transesterification accounted for about 70% of the biodiesel production carbon footprints. Sensitivity analysis revealed that feedstock seed yield per ha is a key determinant of biodiesel's life cycle environmental performance. This study established that B10 from second-generation feedstocks is environmentally more competitive than petroleum-diesel from a life cycle perspective.