Abstract
The purpose of this study is to assess the energy and environmental performance of a mechanochemical method for preparing cellulose nanofibers (CNF) from woody biomass using a life cycle assessment approach. The energy requirements and greenhouse gas (GHG) emissions from CNF production were compared to those of petrochemical polypropylene (PP) production. The functional unit used in this study was 1 kg dry CNF. The background data (emission factor of industrial steam and water, wood density, and grid emission factor etc.) were collected from the Inventory Database for Environmental Analysis (IDEA) and published literature. The foreground data (power, heat, and water requirements in CNF production plant) were obtained from pilot plant experiments. The energy requirements for preparing CNF were 11.1〜30.2 MJ/kg, which were lower than that of PP (63.4 MJ/kg). The GHG emissions of preparing CNF ranged from 1.2〜3.7 kg CO_2 eq./kg, without accounting for carbon fixation of biomass. Water consumption for producing CNF was 17.8〜19.4 L/kg, which was much lower than that of PP (258.6 L/kg). When the CNF were used to produce composite with PP, the maximum GHG reduction was 2.4 kg CO_2 eq./kg, taking into account carbon fixation of biomass. The results showed that the utilization of CNF prepared from woody biomass using the mechanochemical method could contribute to saving energy and mitigating GHG emissions.
