Empirical constraints on the virgin-substitution potential of mechanically recycled PET, PE, and PP in Europe: quality-loss substitutability (cascading pathways and maximum recycled content) and market absorption of large recycled supply

Eriksen et al. (2020) showed with a 50-year dynamic material flow analysis that mechanically recycled PET, PE, and PP could cover 40–65% of European plastic demand under combined circularity initiatives, but only under assumed quality-loss parameters: cascading recycling pathways, per-sector maximum recycled contents, and a fixed rule for handling surplus recyclate. Whether recycled plastic can actually substitute virgin material at that scale depends on three empirically unresolved quantities: how recycling-induced quality loss constrains substitutability by product group and sector, how markets absorb a large increase in recycled supply, and Europe-wide product-level collection, sorting, and reprocessing efficiencies. The problem is to replace these assumptions with empirical characterizations and thereby determine the virgin-material displacement achievable by mechanical recycling for Europe's three most recycling-relevant commodity polymers (PET, PE, and PP), on the basis of measured rather than assumed quality-loss and market parameters.

Background

Polyethylene terephthalate (PET), polyethylene (PE), and polypropylene (PP) are, from a recycling perspective, the three vital commodity polymers in Europe: PE and PP account for about half of European plastic production while PET represents only about 8%, and collectively the three represent more than 85% of the plastic packaging produced in Europe and between 26% and 67% of the plastic produced in other sectors. They are used in packaging, agriculture, automotive, building and construction, electrical and electronic equipment, textile fibers, and other consumer products. Material flow analysis (MFA) is the industrial-ecology method for tracking stocks and flows of a material through an economy; in a dynamic MFA, the flows evolve over time according to product lifetimes and demand growth. Eriksen et al. (2020) built such a model for European PET, PE, and PP flows (EU-27 plus the UK, Norway, and Switzerland), calibrated on a 2016 baseline and projected over 50 years. The model reconciles empirical data into transfer coefficients (TCs), which describe the partitioning of mass input to outputs for each process in the system, obtained by dividing the mass output from a process by its mass input, and which were defined for all processes from European production and trade quantities together with collection, sorting, and reprocessing efficiencies; and it represents quality degradation of mechanically recycled plastic in two ways. First, cascading pathways specify which sector(s) and product group(s) each waste flow may be recycled into: if a flow of a specific product group from a specific sector is recycled into the same product group and sector, the pathway is closed-loop, whereas recycling into another sector and/or product group with lower or similar quality criteria is downcycling, the progressive loss of material quality through reprocessing and reuse. Second, a maximum recycled content, $RC^{max}$, caps the share of recycled material acceptable in each product group and sector so that functionality is not compromised; when the recycled supply in year $n$, $R_n$, exceeds what RCmax-limited demand can absorb, $C_{n+1}\cdot RC^{max}$, the surplus is either further downcycled into low-quality applications or disposed of.

Under baseline conditions the model finds recycling rates of only 13–20% after 50 years, with virgin plastic supplying 85–90% of annual demand. Combining initiatives — constant demand, managed waste exports, design-for-recycling, improved collection, and improved recovery and reprocessing — raises recycling rates above 55%, with 75–90% of recycling closed-loop and 40–65% of annual demand coverable by recycled material; these relative outcomes are obtained both with increasing and with constant demand, the highest recycling rates arising with increasing demand while the closed-loop and substitution shares perform considerably better with constant demand. Absolute reductions in virgin-material consumption additionally require total demand to be stabilized: with increasing demand, virgin material consumption grows dramatically regardless of the recycling and substitution levels reached. Crucially, the quality-related parameters — the cascading pathways, the per-sector $RC^{max}$ values, and the fate of surplus material — were assumptions rather than measurements: the paper states that the consequences of quality reductions, the market conditions of downcycling, and the availability of surplus recycled plastic are poorly understood, and that data on how waste-management systems handle individual product flows were scarce, country-specific, and weakest for non-packaging products. Later work confirms the gap: a review of 49 life-cycle-assessment studies finds that substitutability of recycled for virgin material is still quantified with borrowed, non-harmonized assumptions, often without considering the recyclate's final application (Sanabria Garcia et al. 2023), and even the terminology of downcycling was only standardized in 2022 (Helbig et al. 2022). The open question is therefore what the true virgin-substitution potential of mechanically recycled PET, PE, and PP in Europe is, once quality loss and market absorption are characterized empirically rather than assumed.

Problem Statement

For the European PET, PE, and PP system modeled by Eriksen et al. (2020), determine empirically and at system level: (i) how quality loss through mechanical recycling constrains the substitutability of recycled for virgin material — that is, the cascading recycling pathways and the maximum recycled contents ($RC^{max}$) per polymer, sector, and product group, including for hard-to-recover streams such as black plastics (items pigmented with carbon black, which absorb the near-infrared light used by industrial plastic-sorting scanners and therefore evade automated detection) and fibers (textile filaments that mixed-waste sorting cannot separate); (ii) the market dynamics that follow a large increase in recycled-material supply — specifically, the fate of surplus recycled material when supply exceeds RCmax-limited absorption ($R_n > C_{n+1}\cdot RC^{max}$): whether reduced raw-material prices expand low-quality markets, whether the material is further downcycled, or whether it is disposed of; and (iii) the harmonized, Europe-wide, product-level data on collection, sorting, and reprocessing efficiencies (transfer coefficients, particularly for non-packaging products) needed to constrain (i) and (ii). The common scientific objective uniting these deliverables is to replace the assumption-driven components of the mass-balance model — cascading pathways, $RC^{max}$ values, and surplus handling — with empirically characterized ones, so that the virgin-material displacement achievable by mechanical recycling for these three polymers in Europe becomes a measured quantity rather than a scenario assumption. Deliverables (i)–(iii) jointly constitute this boundary: empirical characterizations of the quality-loss-to-substitutability parameters, of the fate of surplus recyclate, and of the product-level transfer coefficients, each expressed in the model's own definitions, together with the displacement of virgin material that these imply within that model frame, reported under the source study's combined-initiative scenario separately for the constant-demand and the increasing-demand trajectories (the displacement depends on the demand trajectory). A mechanistic forecast of future plastic production lies outside the boundary, as it does in the source study. The related but distinct question of the political and behavioral feasibility of stabilizing or reducing total polymer demand, which the source study flags as a prerequisite for absolute reductions in virgin consumption but explicitly excludes from its mass-balance scope, is adjacent context rather than part of this completion boundary.

References

1. Eriksen, M. K., Pivnenko, K., Faraca, G., Boldrin, A., & Astrup, T. F. (2020). Dynamic Material Flow Analysis of PET, PE, and PP Flows in Europe: Evaluation of the Potential for Circular Economy. Environmental Science & Technology, 54(24), 16166–16175. DOI: 10.1021/acs.est.0c03435. https://doi.org/10.1021/acs.est.0c03435
2. Helbig, C., Huether, J., Joachimsthaler, C., Lehmann, C., Raatz, S., Thorenz, A., Faulstich, M., & Tuma, A. (2022). A terminology for downcycling. Journal of Industrial Ecology, 26(4), 1164–1174. DOI: 10.1111/jiec.13289. https://doi.org/10.1111/jiec.13289
3. Klotz, M., Haupt, M., & Hellweg, S. (2022). Limited utilization options for secondary plastics may restrict their circularity. Waste Management, 141, 251–270. DOI: 10.1016/j.wasman.2022.01.002. https://doi.org/10.1016/j.wasman.2022.01.002
4. Kahlert, S., & Bening, C. R. (2022). Why pledges alone will not get plastics recycled: Comparing recyclate production and anticipated demand. Resources, Conservation and Recycling, 181, 106279. DOI: 10.1016/j.resconrec.2022.106279. https://doi.org/10.1016/j.resconrec.2022.106279
5. Sanabria Garcia, E., Huysveld, S., Nhu, T. T., De Meester, S., & Dewulf, J. (2023). Technical substitutability of recycled materials in life cycle assessment: A comprehensive review and framework for quantification. Waste Management, 171, 324–336. DOI: 10.1016/j.wasman.2023.08.032. https://doi.org/10.1016/j.wasman.2023.08.032
6. Roosen, M., Tonini, D., Albizzati, P. F., Caro, D., Cristóbal, J., Lase, I. S., Ragaert, K., Dumoulin, A., & De Meester, S. (2023). Operational Framework to Quantify "Quality of Recycling" across Different Material Types. Environmental Science & Technology, 57(36), 13669–13680. DOI: 10.1021/acs.est.3c03023. https://doi.org/10.1021/acs.est.3c03023
7. Peragin, L. (2025). Recycled and Virgin Plastics Prices Dynamics: Towards Substitution Effects? Environmental Modeling and Assessment, 31(2), 289–316 (published online 10 December 2025; print issue April 2026). DOI: 10.1007/s10666-025-10089-z. https://doi.org/10.1007/s10666-025-10089-z
8. Gao, Y., & Cabrera Serrenho, A. (2025). Evaluating the potential to reduce the global demand for polymers. Resources, Conservation and Recycling, 223, 108518. DOI: 10.1016/j.resconrec.2025.108518. https://doi.org/10.1016/j.resconrec.2025.108518
9. Gao, Y., Liu, X., Chen, W., Cabrera Serrenho, A., Cimpan, C., & Liu, G. (2025). High-Resolution Mapping of the Nordic Plastic Cycle Suggests Capacity Expansion for Both Mechanical and Chemical Recycling. ACS Sustainable Resource Management, 2(11), 2024–2034. DOI: 10.1021/acssusresmgt.5c00143. https://doi.org/10.1021/acssusresmgt.5c00143
10. Cimpan, C., Bjelle, E. L., Budzinski, M., Wood, R., & Strømman, A. H. (2023). Effects of Circularity Interventions in the European Plastic Packaging Sector. Environmental Science & Technology, 57(27), 9984–9995. DOI: 10.1021/acs.est.2c08202. https://doi.org/10.1021/acs.est.2c08202
11. Stegmann, P., Daioglou, V., Londo, M., van Vuuren, D. P., & Junginger, M. (2022). Plastic futures and their CO2 emissions. Nature, 612(7939), 272–276. DOI: 10.1038/s41586-022-05422-5. https://doi.org/10.1038/s41586-022-05422-5
12. Schmuck, A., Belé, T. G. A., Withoeck, D., Van Geem, K. M., Ragaert, K., & De Meester, S. (2026). Analysis of trade-offs of post-sorting plastic packaging. Nature, 654(8118), 383–390. DOI: 10.1038/s41586-026-10606-4. https://doi.org/10.1038/s41586-026-10606-4
13. Kawecki, D., Wu, Q., Gonçalves, J. S. V., & Nowack, B. (2021). Polymer-specific dynamic probabilistic material flow analysis of seven polymers in Europe from 1950 to 2016. Resources, Conservation and Recycling, 173, 105733. DOI: 10.1016/j.resconrec.2021.105733. https://doi.org/10.1016/j.resconrec.2021.105733
14. Auer, M., Schmidt, J., Diemert, J., Gerhardt, G., Renz, M., Galler, V., & Woidasky, J. (2023). Quality Aspects in the Compounding of Plastic Recyclate. Recycling, 8(1), 18. DOI: 10.3390/recycling8010018. https://doi.org/10.3390/recycling8010018
15. Kawai, M., Nakatani, J., Kurisu, K., & Moriguchi, Y. (2022). Quantity- and quality-oriented scenario optimizations for the material recycling of plastic packaging in Japan. Resources, Conservation and Recycling, 180, 106162. DOI: 10.1016/j.resconrec.2022.106162. https://doi.org/10.1016/j.resconrec.2022.106162