Finding high-impact intervention points for plastic recycling using an exploratory stock-flow model

With the growing impetus to increase the recycling of plastic waste, a more detailed understanding of the impact of different interventions on improving material circulation in the plastic value chain is needed. This paper uses an exploratory stock-flow modeling approach to analyze the impact potential of critical intervention points and their combinations for increasing circularity and reducing linearity in the Finnish plastic recycling system. The results show that interventions at all our selected intervention points—demand, collection, sorting, and processing—are needed to reach the best outcomes in terms of linear material flows. With uncertainty regarding international flows, collection- and sorting-targeting actions are most effective in avoiding the most pessimistic circularity outcomes, whereas demand- and capacity-targeting interventions have the potential to achieve the best optimistic circularity outcomes. The results contribute to previous research on plastic recycling by improving understanding of the critical bottlenecks and synergistic effects of supply- and demand-side interventions, as well as by supporting policy and industrial decision-making by drawing attention to effective combinations of interventions under uncertainty. The analysis also highlights how the coarse resolution structure of the material flow system governs the impact potential of intervention points, while many system parameters are less significant.