(147x) Evaluating Impacts of Carbon Taxes on the Economic Viability and Carbon Footprint of Plastic Production Pathways

Plastics are indispensable in modern society due to the exceptional properties of lightweight, good durability, and inexpensive production cost. Most plastics used in our daily life are manufactured from fossil fuels, including petroleum, coal, and natural gas. However, the reliance on the non-renewable fossil fuel resources could cause the problems of resource depletion. Moreover, the use of fossil fuel will result in substantial greenhouse gas (GHG) emitted to the atmosphere. Therefore, several new production methods using renewable resources have been proposed to avoid the usage of fossil fuels.

Among them, one way is to use biomass as feedstock due to its renewability and ability to absorb carbon dioxide from the atmosphere. Recently, researchers have successfully converted various biomass feedstocks to petrochemicals for further polymer processing. However, most bio-based products are still not economically feasible nowadays, and the mature technologies for producing fossil-fuel based chemicals render them lower production costs. To address the problem, one way is to advance the technologies of biomass conversion to increase product yield. Although this can decrease the production costs of bio-based products, it requires significant time and effort and cannot be achieved in a short term. Another way is to incentivize bio-based products and punish fossil-fuel based products through government regulations, such as imposing a carbon tax, making bio-based products more economically competitive.

In my research, we solve an optimization problem for determining the production schedule of various plastics from either fossil fuels or biomass. Our objective is to find out the production schedule with minimized production cost while satisfying the global demands for various plastics. At the same time, the overall GHG emission is calculated. We will start with the analysis without the carbon tax imposed in the system. In this scenario, most products are produced from fossil fuel feedstocks in the optimized schedule. In addition, the GHG emission contribution from each plastic is obtained. As the carbon tax is imposed, the feedstock for making some plastics will be changed to biomass under the optimized schedule, decreasing the overall GHG emission. We will increase the carbon tax to different levels and solve the optimization problems. When the carbon tax increases to a certain level, carbon neutrality can be achieved. In other words, the net GHG emission will be zero under the optimized production schedule. Governments around the world are committed to achieve carbon neutrality by 2050 to attain the goals of the Paris Agreement. This work can be a preliminary guideline for policymakers to determine the carbon pricing system.

My future work on this project will focus on the study of other environmental impacts (e.g. land use, eutrophication, and fossil resource depletion) from the plastic industry after imposing the carbon tax. In addition, more types of plastics will be incorporated into the optimization framework, making the study more holistic and comprehensive.