Sustainable process design for lignocellulosic-based bioethanol using life cycle assesment technique

Abstract

This study focused on the sustainable process design of a bioethanol conversion process using lignocellulosic biomass as a raw material for fuel ethanol (99.5 wt%) production. The process simulator, PRO/II 8.2, was used to generate the base case design of the bioethanol conversion process using sugarcane bagasse as a feeds tock. The sustainability analysis tool, SustainPro, was used in the analysis of indicators, sustainability metrics, and safety indices, which are further analyzed to provide directions for improvements. The life cycle environmental burdens associated with the bioethanol conversion process was performed by using Life Cycle Assessment software, SimaPro 7.0 with the CML 2 baseline 2000 and Eco-indicator 95 method, to quantify the impacts in various categories such as global warming, acidification, eutrophication, and energy resources. Four new design alternatives were generated based on suggestions from SustainPro, both in the process aspect (Alternatives 1, 2, 3, and 4) and the energy efficiency aspect (Alternative 5). The comparison between base case and new design alternatives was conducted to indicate the improvement for sustainability. Using the heat integrated design, Alternative 5 was shown to be the best option as seen from the lowest impact in all categories studied. The results showed that the greenhouse gas emission mainly come from the recovery and pretreatment stage in the bioethanol conversion process.