As the imposed carbon price increases to $105 per tonne of CO 2 eq, we notice the production of p-xylene will then be shifted to pyrolysis of corn stover. This can reduce the carbon footprint of PET production with 31.7% lower of total GHG emissions in the system. Further increases of carbon price to $450 and $920 per tonne of CO 2 eq in the system can cause the production of propylene and ethylene from feedstock of fossil fuels to biomass, decreasing the carbon footprint of PP, LDPE, HDPE, PVC, and PET production. The largest reduction (-459 MtCO 2 eq) of GHG emissions can be achieved as the imposed carbon price is raised to $920 per tonne of CO 2 eq, which can cut 63.5% of total emissions in plastic industry. However, this will drive the total production cost in the system up by 65.5% to $890.8 billion per year, which is clearly unreasonable. It is interesting to observe that the limiting reduction of carbon footprint is 65.5% (it is not possible to fully decarbonize the system); this is because negative footprints of biomass feedstocks cannot offset the positive footprints of the corresponding technologies. We also used the model for analyzing the total use of fossil and biomass feedstocks at different carbon prices, see Figure . Similarly, we observe the five stages of usage for the feedstocks. As the carbon price increases from $0 to $920 per tonne of CO 2 eq, the usage of fossil fuels for the plastic production is reduced by 23.7% from 357.2 to 272.6 million tonnes per year, while biomass usage increases from 0 to 813.2 million tonnes per year. The total production cost and GHG emissions in the system as a function of carbon price are presented in Figure . The increased production cost is mainly due to the additional cost paid for the GHG emissions from either the technologies or the feedstocks. Thus, the total production cost increases linearly with the imposed carbon price. The total GHG emissions are reduced stepwise as the level of carbon price rises, introducing a direct trade-off.