Technical, Economic, and Environmental Comparison of Closed-Loop Recycling Technologies for Common Plastics

Abstract

Over 400 million metric tons of plastic waste are generated globally each year, resulting in pollution and lost resources. Recycling strategies can recapture this wasted material, but there is a lack of quantitative and transparent data on the capabilities and impacts of these processes. Here, we develop a data set of material quality, material retention, circularity, contamination tolerance, minimum selling price, greenhouse gas emissions, energy use, land use, toxicity, waste generation, and water use metrics for closed-loop polymer recycling technologies, including mechanical recycling and solvent-based dissolution of polyethylene, polyethylene terephthalate (PET), and polypropylene, as well as enzymatic hydrolysis, glycolysis, and vapor methanolysis of PET. Mechanical recycling and PET glycolysis display the best economic (9%−73% lower than competing technologies) and environmental (7%−88% lower) performances, while dissolution, enzymatic hydrolysis, and methanolysis provide the best recyclate material qualities (2%−27% higher). We identify electricity, steam, and organic solvents as top process contributors to these metrics and apply sensitivity and multicriteria decision analyses to highlight key future research areas. The estimates derived in this work provide a quantitative baseline for comparing and improving recycling technologies, can help reclaimers identify optimal end-of-life routes for given waste streams, and serve as a framework for assessing future innovations.

Method to Develop Potential Business Cases of Plastic Recycling from Urban Areas: A Case Study on Nonhousehold End-Use Plastic Film Waste in Belgium

“…To date, different methods have been investigated in previous studies, , which require further analysis of the technical properties (e.g., melt flow index, viscosity, etc.) of rPE basic/advanced . − …”

Three ways to solve the plastics pollution crisis

“…The technology remains costly. One 2023 estimate by Gregg Beckham, a chemical engineer at the US National Renewable Energy Laboratory in Golden, Colorado, and his colleagues suggest that enzymatically recycled PET might currently cost around twice as much as the virgin product, and around four times as much as the mechanically recycled one; it also uses more energy and emits more greenhouse gases than does mechanical recycling 4 .…”

Circularity in polymers: addressing performance and sustainability challenges using dynamic covalent chemistries

“…228 Over the last few years, several TEA and LCA studies have been published on the recycling of commercial polymers. 33,[229][230][231][232][233][234][235][236] In a recent example, the LCA of an exploratory, lab-scale synthetic process for the upcycling of poly(acrylic acid) revealed a 10-fold decrease in global warming potential (kg CO 2 kg −1 ) and cumulative energy demand (MJ kg −1 ) when an acid-catalyzed hydrolysis approach was employed vs. a base-mediated route. 237 The study revealed key method optimization parameters to minimize the impact on the environment at an industrial scale, which may have been overlooked in a lab-scale study that excluded LCA.…”