Potential trade-offs between eliminating plastics and mitigating climate change: An LCA perspective on Polyethylene Terephthalate (PET) bottles in Cornwall

Abstract

The aim of this study is to investigate whether eliminating plastics entirely under existing waste infrastructure and management practices could have an adverse effect on climate change, using a case study on the hypothetical substitution of Polyethylene Terephthalate (PET) with glass as the material for bottling liquids in the domestic sector in Cornwall, England. A life cycle environmental impacts-based model was created using high resolution local data on household waste and current management practices in combination with Life Cycle Assessment (LCA) datasets. The model allows users to define key system parameters such as masses of materials, transport options and end-of-life processes and produces results for 11 environmental impact categories including the Global Warming Potential (GWP). The results from the application of this model on the case study of Cornwall have shown that the substitution of PET with glass as the material for bottling under the current waste infrastructure and management practices could lead to significant increases in GWP and hinder efforts to tackle climate change. A sensitivity analysis of the glass/PET mass ratio suggests that in order to achieve equal GWP the glass bottles need to become approximately 38% of the weight they are now. Increasing the recycled content and decreasing losses during the recycling processes could also help lower the GWP by 18.9% and 14.5%, respectively. This model can be expanded further to include more types of plastics and other regions to evaluate designs of new regional circular economy with less plastics waste and pollution. Our study suggests that it is necessary and crucial to consider the specific waste infrastructure and management practices in place and use science-based models that incorporate life cycle thinking to evaluate any solutions to plastics pollution in order to avoid problem shifting.