A Comparative Life Cycle Assessment Study of Polyethylene Based on Sugarcane and Crude Oil

Artikel i vetenskaplig tidskrift, 2012

A potential strategy for tackling the negative environmental impact of conventional plastics is to produce them from renewable resources. However, such a strategy needs to be assessed quantitatively, by life cycle assessment (LCA) for example. This screening LCA is intended to identify key aspects that influence the environmental impact of sugarcane low-density polyethylene (LDPE) and compare these results against fossil-based LDPE. The study showed that the major contributors to the environmental impact of sugarcane LDPE are ethanol production, polymerization, and long-distance sea transport. The comparison between sugarcane- and oil-based plastics showed that the sugarcane alternative consumes more total energy, although the major share is renewable. Moreover, for their potential impacts on acidification, eutrophication, and photochemical ozone creation, no significant difference between the two materials exists. However, with regard to global warming potential (GWP), the contribution of land use change (LUC) is decisive. Although the range of LUC emissions is uncertain, in the worst case they more than double the GWP of sugarcane LDPE and make it comparable to that of fossil-based LDPE. LUC emissions can thus be significant for sugarcane LDPE, although there is need for a consistent LUC assessment method. In addition, to investigate the influence of methodological choices, this study performed attributional and consequential assessments in parallel. No major differences in key contributors were found for these two assessment perspectives.