Exergetic analysis of a biodiesel production process from Jatropha curcas

As fossil fuels are depleting day by day, it is necessary to find an alternative fuel to fulfill the energy demand of the world. Biodiesel is considered as an environmentally friendly renewable diesel fuel alternative. The interest in using Jatropha curcas as a feedstock for the production of biodiesel is rapidly growing. On the one hand, J. curcas' oil does not compete with the food sector due to its toxic nature and to the fact that it must be cultivated in marginal/poor soil. On the other, its price is low and stable. In the last decade, the investigation on biodiesel production was centered on the choice of the suitable raw material and on the optimization of the process operation conditions. Nowadays, research is focused on the improvement of the energetic performance and on diminishing the inefficiencies in the different process components. The method of exergy analysis is well suited for furthering this goal, for it is a powerful tool for developing, evaluating and improving an energy conversion system. In this work, we identify the location, magnitude and sources of thermodynamic inefficiencies in a biodiesel production process from J. curcas by means of an exergy analysis. The thermodynamic properties were calculated from existing databases or estimated when necessary. The higher exergy destruction takes places in the transesterification reactor due to chemical reactions. Almost 95% of the exergy of the fuel is destroyed in this reactor. The exergetic efficiency of the overall process is 63%. (C) 2012 Elsevier Ltd. All rights reserved.