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The aim of this study is to evaluate the land requirement, energy consumption and GHG (greenhouse gases) emissions of microalgal biodiesel (M-BD) and Jatropha curcas seeds (J-BD) based biodiesel from the perspective of life cycle assessment (LCA). Mass and energy balance was used through the whole LCA calculation for each process. Two types of biodiesel (100% biodiesel: BD100, and 20% blends of biodiesel: BD20) were assumed to be combusted in the suitable diesel engine. Displacement method was adopted to measure the co-products credits. The results showed that the land requirement of producing 1 kg biodiesel from microalgae was about 1/31 of that from Jatropha curcas seeds. The well to pump (WTP) stage for microalgal biodiesel had higher fossil energy requirement but lower petroleum energy consumption and GHG emissions compared to Jatropha curcas and conventional diesel (CD). The WTP energy efficiency for J-BD100 and M-BD 100 were 26% and 17.4%, respectively.

This study provides an LCA of coal derived DME vehicle fuel cycle. Two DME production systems were evaluated, one is single DME production system, and the other is DME/IGCC cogeneration (polygeneration) system. The effects of CCS technology on energy use and GHG emissions were analyzed. For single DME production design, WTW total energy use and fossil energy is about 80% larger than that for petroleum diesel production, and increases life-cycle GHG emissions by more 200% relative to petroleum diesel. Results for DME/IGCC production design pathway from displacement method are almost the same with the petroleum diesel pathway. CCS incurs an energy penalty of 7-16%.