Life cycle assessment of biofuels in China: Status and challenges

Biofuels using as transportation fuels represents great potential for reduction of fossil energy consumption and mitigation of greenhouse gases (GHG) emissions. China has undertaken ambitious targets and relevant policies to promote the development of biofuel industry. But a general picture showing the environmental sustainability of biofuels in China has been lacking. A comprehensive review of life cycle assessment (LCA) of bioethanol and biodiesel in China is presented in this study. Most of the surveyed studies have not gone beyond energy and GHG emission assessments. A high variability of fossil energy consumption and GHG emissions has been observed, especially for bioethanol. Cellulosic bioethanol has the best performance on reduction of fossil energy consumption. Bioethanol produced from corn, wheat, sweet sorghum and sugar crops are more energy intensive and less competitive for fossil energy saving. Significant disagreement and controversies exist regarding the GHG benefits of bioethanol, especially that of the starch- and sugar-based bioethanol. In contrast, biodiesel using as a substitute of conventional diesel can generally ensure net reductions of fossil energy consumption and GHG emissions. LCA results exhibit strong dependency on methodological choices such as system boundary and allocation method. The study identifies methodological constraints in surveyed studies and concludes with future challenge and recommendations.