A complex systems dynamics investigation on mechanical and chemical recycling competition in closing the loop of plastic

Abstract The current deployment of recycling technology is insufficient to achieve a circular economy for plastics. While many studies acknowledge the potential of integrating chemical recycling (CR) into the plastic value chain, the competitive or synergistic relationship with conventional mechanical recycling (MR) remains unclear. This study employs a system dynamics approach to provide a techno-economic assessment of the effects of changes in sorting and recycling technologies over a 15-year period (2019–2033) within the empirical context of Lombardy, Italy. Results show that the integrated deployment of MR and CR can increase plastic recycling by up to 75% compared to business as usual. While recycling rates for sorted plastics increased by approximately 80%, the resulting secondary raw materials only partially offset a growing total demand that still necessitates raw material imports. In our simulations, fear of competition between CR and MR is not economically justified, as there is no scenario in which abandoning MR makes sense and achieving optimal systemic scale through a diversified portfolio of MR and CR is more critical for success than specific technology choices. These findings provide system-dynamics insights and actionable techno-economic pathways for practitioners and policymakers to optimize the MR-CR technological mix and suggest directions for future research.