Biogas and bioethanol production from pinewood pre-treated with steam explosion and N-methylmorpholine-N-oxide (NMMO): A comparative life cycle assessment approach

In this study, the lignocellulosic biofuel production from pinewood, pretreated with steam explosion and N-methylmorpholine-N-oxide (NMMO), was investigated from a life cycle perspective in Sweden. To perform this study four scenarios, i.e. ethanol and biogas production by NMMO (Sc-1) and steam explosion (Sc-3) pretreatments, and biogas production by NMMO (Sc-2) and steam explosion (Sc-4) pretreatments, were developed. The consequential life cycle assessment (CLCA) methodology with a cradle to gate approach was employed and two functional units, i.e. 105,263 tonnes pinewood input to the biofuel plant and 1 MJ energy produced, were selected in order to assess the environmental impacts of pinewood-based biofuel production. The results revealed that bioenergy production with NMMO-based pretreatment method was more environmentally friendly than steam explosion process in terms of human health, ecosystem quality, resources and climate change. Moreover, it was shown that the Sc-2 in which methane was the single outcome of the plant (the main product) outperformed the other scenarios in terms of environmental performance and energy balance. (C) 2016 Elsevier Ltd. All rights reserved.