Optimal plastic recycling system and technology development could accelerate decarbonization: A case study from Japan

This study provided a geographic and technical matching approach supporting low-carbon style recycling systems, demonstrated using polyvinyl chloride waste (PVCW) generated in 2018 in Mie Prefecture, Japan. From a carbon dioxide (CO₂) emission basis, mechanical/material recycling (MR) and energy recovery facilities were all allocated full capacity; however, parts of chemical recycling facilities were excluded in the optimal solutions. From the spatial distribution of the allocated result, we confirmed a trend that to achieve the minimum total emissions, the matchings from pretreatment to recycling facilities were done based on a nearby priority rule. From an emission reduction basis, MR accounted for the major proportion of total reductions which was similar to that accessed from an emission basis. Thus, the promotion of MR should be prioritized at the current technical level when optimizing emissions of the whole lifecycle. The number of facilities allocated were substantially reduced; meanwhile, the averaged emission reductions per ton of PVCW disposed were increased from the current level (2.93) to the near-future level (4.99 t-CO₂ t^-1). Thus, we concluded that this optimization under a higher technical level was effective to make the current recycling system with more emission reductions (low-carbon environmental effect) and require fewer disposal facilities (cost-saving economic effect). Meanwhile, certain long-distance routes found in solutions implied that technical parameters were more important than geolocation parameters to achieve maximum emission reductions.