Emergy evaluation of biofuels production in Thailand from different feedstocks

• Emergy evaluation of seven alternative fuel productions in Thailand was presented.
• Sustainability between oil palm and jatropha systems were compared in this study.
• Simulation models were performed to optimize the systems efficiency.
• Wastes were utilized to reduce non-renewable consumption within the systems.
• Sustainability was controlled by imported and non-renewable resources.

Energy demand in Thailand has steadily increased over the years. The aim of this study is thus to investigate whether the use of biodiesel, as an alternative transportation fuel, can provide a sustainable solution for future energy supply in Thailand. Seven different production cases have been classified in two main groups, three actual systems and four proposed systems. These were then investigated using emergy analysis. In the actual cases, the emergy indices indicated that case study B (biodiesel production from palm oil in industrial scale) gave the highest sustainability with emergy yield ratio (EYR), environmental loading ratio (ELR) and emergy sustainability index (ESI) recorded at 1.19, 5.18 and 0.23, respectively. Moreover, industrial scale biodiesel production appeared to be more practical in real-world operation when considering production yields. In the simulated cases, Case G (biofuels production process with steam and electricity generation zones), which utilized all waste residues to produce power and heat, was the best case with results for EYR, ELR and ESI of 1.17, 4.89 and 0.24. The best case in this study can slightly improve the emergy sustainability index. The system sustainability is still insufficient since a high portion of imported and non-renewable sources have been consumed. In pursuing sustainable development, current biomass production and biofuels conversion technologies should be improved to minimize energy and raw materials consumption. Then, the biodiesel from biomass can be considered as a suitable sustainable alternative fuel.