Assessing the Environmental Benefits of Technology Pathways for Plastic Recycling

The United States remains the world's leading generator of plastic waste, with per capita waste generation five times higher than the global average. Current technologies and infrastructure do not allow for high circularity of plastics, resulting in low recycling rates. For instance, the U.S. plastic recycling rate is about 5% to 9%. Recent engineering developments in plastic recycling promise to help increase this figure. The environmental benefits of novel recycling processes have been studied in the literature via life cycle assessment, but the results are highly variable and uncertain. In this work, we created a comprehensive database featuring the greenhouse gas (GHG) emissions of virgin plastics production and recycling technologies from a product perspective. Waste-to-product recycling pathways are defined for various technologies and chemical products. Using this database, we developed a computational framework to quantify uncertainty in the reduction of emissions by each pathway. The results show that mechanical processes and solvent-based technologies using temperature reduction for precipitation have the greatest potential to reduce GHG emissions, with up to 60% savings. Pyrolysis pathways also have the potential to reduce emissions by up to 53% compared to the virgin production of ethylene. Solvent-based processes using antisolvents for precipitation yield unfavorable results; most pathways are estimated to increase emissions. As the plastics life cycle assessment literature grows, future work could expand upon this study by creating a larger database and including other novel technologies, such as enzymatic recycling and other depolymerization pathways.