Global Warming Potential and Fossil-Energy Requirements of Biodiesel Production Scenarios in South Africa

Life cycle assessment has been used to investigate the global warming potential (GWP) and fossil-energy requirements of the production of biodiesel from canola (oilseed rape), soybean, and sunflower oils in South Africa. The effect of scale and transportation of raw materials and products was investigated, as well as the effect of ploughing grassland and using irrigation to grow oil crops. This research shows that the GWP and fossil-energy requirements of biodiesel produced in South Africa vary widely, depending upon predominantly the crop yield, the requirement for irrigation, and the ploughing of uncultivated land. For the best case scenario, where no uncultivated land is newly ploughed and irrigation is not required, biodiesel has a GWP 20−36% lower than that of the fossil diesel mix currently used in South Africa and a fossil-energy requirement 50−62% lower. However, in the worst case scenario, where oil-seed crops are grown on newly cultivated land requiring substantial irrigation, this paper concludes that biodiesel can have a GWP significantly higher than South African fossil diesel. The scale of operation and transport distances involved are shown to have little influence on the GWP and fossil-energy requirement of biodiesel produced in South Africa.