The production pathways that motivate our modeling framework are shown in Figure . Here, we target seven main plastics as final products, including low-density polyethylene (LDPE), highdensity polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyethylene terephthalate (PET), and Nylon 66 (N66). The starting materials are selected from either fossil or biomass feedstocks, including natural gas (NG), petroleum naphtha (PN), corn stover, sugar beet, and sugarcane. We can immediately see that the production pathways show complex interdependencies, as they are connected via different technologies that use/produce common input, intermediate products, and final products. The interconnectivity makes it difficult to identify optimal pathways. For example, LDPE can be produced either through fossil or biomass feedstocks. For the fossil pathway, PN is first converted to ethylene (EL) through catalytic reforming, and then ethylene is polymerized to LDPE while, for the biomass pathway, sugar beets are converted to ethanol via fermentation, and then ethanol is dehydrated to EL and polymerized to LDPE. As such, dehydration is the key technology that couples fossil-and biomass-based pathways to LDPE.