Life cycle assessment of biodiesel from soybean, jatropha and microalgae in China conditions

Increasing demand for transport fuels has driven China to attach great importance to biodiesel development. To evaluate the environmental impacts caused by producing and driving with biodiesel made from soybean, jatropha, and microalgae under China conditions, the LCA methodology is used and the assessment results are compared with fossil diesel. The solar energy and CO2 uptake in biomass agriculture and reduction of dependency on fossil fuels lead to a better performance on abiotic depletion potential (ADP), global warming potential (GWP), and ozone depletion potential (ODP) in the life cycle of biodiesel compared to fossil diesel. Except for ADP, GWP and ODP, producing and driving with biodiesel does not offer benefits in the other environmental impact categories including eutrophication, acidification, photochemical oxidation, and toxicity. Jatropha and microalgae are more competitive biodiesel feedstock compared to soybean in terms of all impacts. By using global normalization references and weighting method based on ecotaxes, the LCA single score for the assessed 10 mid-point impact categories of soybean, jatropha, and microalgae based biodiesel is 54, 37.2 and 3.67 times of that of fossil diesel, respectively. Improvement of biomass agriculture management, development of biodiesel production technologies, bettering energy structure and promoting energy efficiency in China are the key measures to lower environmental impacts in the life cycle of biodiesel in the future. Various sensitivity analyses have also been applied, which show that, choice of allocation method, transport distance, uncertainty in jatropha and microalgae yield and oil content, and recycling rate of harvest water of microalgae have significant influence on the life cycle environmental performance of biodiesel.