Systems Analysis Approach to Polyethylene Terephthalate and Olefin Plastics Supply Chains in the Circular Economy: A Review of Data Sets and Models

The environmental and economic impacts of implementing a circular economy in plastic waste supply chains are not well understood. The proposed systems analysis framework assesses environmental, social, and economic impacts of plastic waste supply chains in a circular economy. The first objective of this article is to identify data sets, models, and knowledge gaps associated with waste plastic supply chain processes, mainly in the U.S. Our literature review indicated that the best data sets exist for virgin plastic resin production, mechanical recycling, landfilling, and incineration, with the materials recovery facility being intermediate, and with chemical recycling the lowest. The second objective of this perspective is to develop an illustrative application of the framework by conducting a preliminary systems analysis of PET bottles with closed-loop recycling. The preliminary systems analysis of polyethylene terephthalate (PET) bottles utilized a linear programming optimization method. Our optimization model indicated that both chemical and mechanical recycling processes are needed to achieve a true circular economy of PET bottles with the least greenhouse gas emissions, specifically reductions of 24% when compared with the linear economy. Good quality and standardized life cycle assessment and techno-economic analysis studies are needed to better understand the environmental, economic, and social impacts of advanced sorting and chemical recycling technologies.