Life cycle assessment of Jatropha curcas biodiesel production: a case study in Mexico

The potential of liquid biofuels (like bioethanol and biodiesel) to reduce greenhouse gas (GHG) emissions from the transportation sector has generated a great deal of interest in the last few years, with particular attention being given to Jatropha methyl ester (JME). Jatropha curcas (Jc)—a species native to Mexico—shows some promise as a source of oil for biodiesel. A few studies on biodiesel production from Jc have been conducted in Mexico, but just one study involved a life cycle assessment (LCA) of JME. At the international level, most studies dealing with Jc focus on the biodiesel industrial process, while in this paper we also look in detail at the agricultural production phase. This case study provides preliminary results on GHG emissions and energy balances of JME production in Mexico, applying the LCA methodology recommended by the European Renewable Energy Directive (RED). Four production systems (JME 1–4) were studied, resulting in GHG mitigation of between 41 and 53% with regards to diesel if no direct land-use change (dLUC) change occurs. However, when accounting for GHG emissions arising from direct land-use change (dLUC), total emissions increase from 40 to 508 kg CO₂e/GJ. The differences between dLUC on tropical dry forest and dLUC on grassland are of lesser importance than those between systems with and without dLUC. Using JME from plantations on lands, previously not cultivated, leads to GHG emissions three or six times higher than using fossil diesel. These results are an approximation to the environmental and energetic impacts of JME production in Mexico. Further studies should be performed before implementing more plantations to produce biofuel from J. curcas.