We Should Use Jatropha as the Feedstock for Producer Gas Production Rather than Biodiesel Production

Net energy analysis (NEA) of Jatropha biodiesel production has been extensively carried out, but the net energy ratio (NER) is very low due to the high energy input consumption for seed pressing and oil processing. Gasification technology is an alternative that can avoid seed pressing and oil processing. This study intends to compare two system boundaries of Jatropha bioenergy production per hectare plantation for a 20-year life cycle. System boundary 1 includes shell producer gas, biodiesel, and seedcake producer gas; while system boundary 2 integrates shell producer gas and seed producer gas. The results highlight that the net energy balances (NEBs) of system boundaries 1 and 2 are 2,449 GJ and 3,552 GJ, respectively. Surprisingly, the NER of system boundary 2 is 49.5, while the NER of system boundary 1 is 3.5. The CO 2 emissions of system boundaries 1 and 2 are 574 tonnes and 636 tonnes, respectively, which implies that the CO 2 emission of system boundary 2 is 10.8% higher than that of system boundary 1. The NEB of system boundary 2 is 41% higher than that of system boundary 1. Correspondingly, system boundary 2 is more efficient than system boundary 1 for energy conversion and utilization