Life cycle assessment of bioethanol from corn stover from soil phytoremediation

Bioethanol is the most widely used biofuel in the world. Bioethanol production from biomass is a way to reduce crude oil consumption and the environmental pollution. This work aims to evaluate the potential environmental impacts of bioethanol production from corn stover obtained from phytoremediation, comparing four different acids (Sulfuric, Nitric, Hydrochloric and Acetic acids) to perform the biomass pre-treatment. The study follows a life cycle thinking perspective, accounting for all the life cycle stages from corn stover grinding, to biomass pre-treatment, enzymatic hydrolysis, fermentation, filtration and ethanol distillation, on a “gate-to-gate” approach. The life cycle inventory was developed using mainly primary data from laboratorial experiments, and complemented whenever necessary with information from literature and from the Ecoinvent V3.0 database available in the SimaPro 8.0.2 software. For the environmental impact assessment, the ILCD Midpoint 2011 methodology was used. Results show that in general, the sulfuric and hydrochloric acids have a better environmental performance than the acetic and nitric acids. Also, results show that pre-treatment, followed by enzymatic hydrolysis are the process steps with the highest relative contribution to the potential environmental impacts. Thus, an improvement analysis should focus on these process steps, for example to reduce fossil energy consumption by implementing renewable energy sources