Life Cycle Land Requirement, Energy Consumption and GHG Emissions of Biodiesel Derived from Microalgae and Jatropha curcas Seeds in China 2014-01-1964

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. The feedstock growing stage of microalgae and Jatropha curcas was found to be the most fossil energy-intensive stage. The WTW results showed good performance for MBD100 on petroleum consumption and GHG emissions. The high fossil energy use for microalgae BD100 was attributed to the large inputs for microalgae growth, including fertilizer and process fuels. Among feedstock, fuel and vehicle operation, the vehicle operation stage had no contribution to BD100, but had great contribution to BD20 blends. At the current technology situation, microalgae based biodiesel should break through many obstacles to make algal based biodiesel more feasible in the future.