The environmental performance of pretreatment technologies for the bioconversion of lignocellulosic biomass to ethanol

Abstract

Ethanol production from switchgrass has the potential to reduce life cycle GHG emissions by 77–97% relative to petroleum based fuels. This study examines the environmental performance of the chemical pretreatment process employed during lignocellulosic conversion to ethanol in an effort to minimise the environmental impact of pretreatment processing techniques. The study quantifies the impact of four pretreatment chemical processes employing sodium hydroxide, ammonia, methanol and sulphuric acid on five environmental indicators, in order to identify the pretreatment process with the lowest environmental impact. Using SimaPrò life cycle assessment software the emissions output to air, soil and water contributing to the environmental parameters: global warming potential (GWP), eutrophication, acidification, photochemical oxidation demand and marine and human ecotoxicity were assessed.Pretreatment employing methanol exhibited the lowest GWP of the four chemicals analysed, with the highest GWP values observed for sodium hydroxide. In general, emissions output varied significantly between all four pretreatment chemicals when compared using selected environmental parameters. Pretreatment employing methanol was identified as having the lowest environmental.