Environmental life cycle assessment of polypropylene made from used cooking oil
Christian Moretti, Martin Junginger, Li Shen
Abstract
Used cooking oil (UCO) has received much attention as feedstock for the production of renewable fuels and bio-based materials. This study aims to assess the environmental impact of UCO-based polypropylene (PP) by a cradle-to-factory gate Life-Cycle Assessment (LCA). 16 impact categories were assessed. The results were interpreted with normalization and weighting steps. For several multi-output processes, different allocation procedures were scrutinized. On a normalized and weighted basis, the environmental impacts of UCO-based PP are dominated by climate change (28%), fossil resource use (23%) and water use (11%). The following environmental hotspots are identified: the polymerization process (38%), the production of hydrogen (21%), the production of LPG (18%) and the combustion of LPG (8%). Compared to petrochemical PP, cradle to factory gate impact reductions of 40–62% for climate change and 80–86% for fossil fuel resource use can be achieved by UCO-based PP, depending on the allocation approach chosen. For other impact categories, the environmental footprint of bio-based PP is strongly influenced by the choice of the allocation method.