Life cycle assessment of bio-based and fossil-based plastic: A review

This review assesses the state-of-the-art in comparative Life Cycle Assessment of fossil-based and bio-based polymers. Published assessments are critically reviewed and compared to the European Union Product Environmental Footprint (EU PEF) standards. No published articles were found to fully meet the standards, but the critical review method was used to classify the articles by their level of compliance. 25 articles partially met the PEF standards, giving 39 fossil-based and 50 bio-based polymer case results. Ultimately, it was possible to compare seven bio-based polymers and seven fossil-based polymers across seven impact categories (energy use, ecotoxicity, acidification, eutrophication, climate change, particulate matter formation and ozone depletion). Significant variation was found between polymer types and between fossil-based and bio-based polymers, meaning it was not possible to conclusively declare any polymer type as having the least environmental impact in any category. Significant variation was also seen between different studies of the same polymer, for both fossil-based and bio-based polymers. In some cases this variation was of the order of 400%. Results suggest that a large part of this variation is related to the Life Cycle Assessment methodologies applied, particularly in the end-of-life treatment, the use of credits for absorbed Carbon Dioxide, and the allocation of multifunctional process impacts. The feedstock source and processing method assumed for bio-based polymers were also major sources of variation. The challenges of Life Cycle Assessment, particularly in a complex, geographically diverse and young industry like bio-based polymers, are recognised. It is proposed that the PEF standards should be adopted more widely in order to homogenise the methods used and allow meaningful comparison between LCA studies on fossil-based and bio-based polymers, and between studies of the same polymers.