Closing the Loop on the Plastics Dilemma Proceedings of a Workshop–in Brief (2020) / Chapter Skim
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Closing the Loop on the Plastics Dilemma: Proceedings of a Workshop - in Brief
Closing the Loop on the Plastics Dilemma: Proceedings of a Workshop - in Brief
Pages 1-14
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Beckman continued that the low recycling rates have led to a dramatic buildup of plastic waste in the environment, some of which will persist for hundreds of years. About 10 million tons of synthetic polymer material enters the ocean each year; it is estimated that by 2050 the mass of polymers in the ocean will outweigh the mass of fish (WEF 2016)
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Although recycling rates are low -- and dropping -- mechanical recycling and chemical recycling offer promise as a way to "close the loop" by recovering materials and thereby reducing the need to produce new materials. Riise stated that mechanical recycling is particularly attractive because it uses only 10–20% of the energy required to make virgin plastics.
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Approaches to those challenges include improvement in mechanical separations, cleaning technologies, and analytic techniques; the use of additives; dilution of virgin plastics with recycled materials; and the use of recycled materials in the most appropriate applications. Although technical limitations and economic challenges remain, Riise concluded that mechanical methods can effectively recycle plastics from complex streams and bring us closer to a circular economy.
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Riise replied that the degree to which that is a problem depends on what products are created from recycled materials and their corresponding lifespans; chemical recycling methods or improvements in mechanical processing to stabilize recycled materials could also help. Robertson added that this issue also suggests a need for better analytic techniques to characterize material inputs, such as a "molecular barcode" reader, which Beckman theorized could identify the origin and properties of plastics as they enter the recycling pipeline.
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CHEMICAL AND BIOLOGIC RECYCLING OF PLASTICS The second workshop session opened with an overview of chemical and biologic recycling by Jeannette Garcia, global lead for Quantum Applications in Quantum Chemistry and Science at IBM Research. Garcia explained that current recycling methods fall into four categories: primary recycling or reuse (recycling products for the same use)
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He closed, however, with a warning that the systems are extremely complex and that one needs to review methods carefully to understand what the data mean and whether they are relevant to a particular system. Putting fundamental principles into practice, Jennifer Le Roy, research and development lead at BioCellection, Inc., described how her company is working to scale thermal oxidative depolymerization processes for converting plastic waste into new products.
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About 150 billion pounds of PET is manufactured each year, and only a small fraction is recovered and reused. Mechanical recycling methods are available for PET, but they require high temperatures, low or no contamination, and non-colored materials.
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Boyd and Allen emphasized the need for different funding mechanisms, especially ones that would support cross-disciplinary collaboration. Several speakers discussed the need to pursue synergies among mechanical, chemical, and biologic recycling methods; to integrate life-cycle assessment and technoeconomic analyses into the process; to create academic–industry partnerships; and to encourage a greater availability of industry data that would help to inform priorities and speed efforts.
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In his view, chemical recycling methods are the most promising for creating the circular economy. Key challenges, however, include minimizing energy inputs for depolymerization, maximizing depolymerization selectivity, and balancing recyclability and performance.
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With respect to research methods, Chen noted that computationally assisted design is useful for investigating infinitely recyclable plastic systems -- both to develop new materials and to improve chemical recycling methods. Modeling and Predictive Analysis Linda Broadbelt, Sarah Rebecca Roland Professor and associate dean for research in the McCormick School of Engineering and Applied Science of Northwestern University, discussed how computational modeling and data science can be used to advance chemical recycling strategies and polymer design.
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Susannah Scott asked about the challenges of designing polymers that have multiple ends of life and the difficulties that can arise when plastics intended for one process (such as mechanical recycling) end up in another process (such as chemical recycling)
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Xu noted that the selection of factors to include in the assessment has an important influence on the results and how they should be interpreted. Insights on Plastics Wang offered examples of how one LCA tool, the GREET model developed by Argonne National Laboratory,4 has been used to analyze alternative means of producing plastics and managing plastic waste.
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National Renewable Energy Laboratory Technical Report 5100-65509. Bremer, M
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The statements recorded here are those of the individual workshop participants and do not necessarily represent the views of all participants, the planning committee, the Chemical Sciences Roundtable, or the National Academies. To ensure that this proceedings meets institutional standards for quality and objectivity, it was reviewed in draft form by Carol Bessel, National Science Foundation, and Linda Broadbelt, Northwestern University.
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