Life Cycle Assessment (LCA) of Wood Flour and Pellets for Manufacturing Wood-Plastic Composites (WPCs)

Abstract

This study is expanding the previous studies that were focused on the material properties and transportation costs of the two alternative feedstocks for manufacturing wood-plastic composites (WPCs): wood flour and pellets. Besides the material properties and cost analysis, life-cycle assessment (LCA) is equally important to assess the environmental impacts of these two alternative wood feedstocks to manufacture WPCs and gain the knowledge of influences from the manufacturing and transportation processes. The main goal of this study was to compare the environmental impacts from the production and transportation of wood flour and pellets utilized in WPC manufacture. The environmental impacts on air, water, soil and human health, as well as the cumulated energy consumption for one tonne and one truckload of the two wood feedstocks were compared. The case-study was based on a commercial wood pellet manufacturer in the state of Maine (ME). The cradle-to-gate approach was considered including the processing of mill residues, manufacturing of the two feedstocks and transporting them to commercial WPC manufacturers. LCA analysis showed that transportation of both feedstocks had the highest impact on the environment as opposed to the inputs associated with production. The global warming potential (GWP) from one tonne production and shipment of wood flour was higher by 8% compared to the pellets. One tonne production and shipment of wood pellets appears more environmentally friendly. Normalization results of one truck load of wood flour (22 tonnes) and pellets (30 tonnes) showed similar environmental impacts. Based on this study, from an environmental perspective, it is inferred that besides use as bio-fuels, wood pellets could be a better alternative feedstock for the manufacture of WPCs.