Process simulation based life cycle assessment for bioethanol production from cassava, cane molasses, and rice straw

The process simulation technique is integrated into life cycle assessment (LCA) in this study to reduce biased parameters in process data collection and perform a fair comparison among different processes. Bioethanol production processes from cassava, cane molasses, and rice straw are studied as an example, to show the usability of process simulation. The simulation results are compared with actual bioethanol plant data to validate the reliability of the technique. The study is a comprehensive LCA comparison, based on unbiased process data from simulations, and minimum variations in other settings, i.e., process fuel type, waste recovery options, etc. The results show that cleaner process designs, using simulations with renewable process energy and sustainable waste recovery, improve the energy efficiency, renewability, and environmentally-benign aspects of the three bioethanol feedstocks. Bioethanol from cassava shows the best values of net energy ratio (1.34), renewability (5.16), and reduced greenhouse gas emissions (410 kg CO2 eq/1000 L). The unbiased LCA results from net energy analysis, and environmental impact assessment, including emissions/hotspot identification and sensitivity analysis, are comprehensively discussed. The simulation technique in this study is also adaptable for future LCA of new/modified processes.