(648a) Modeling Direct and Indirect Carbon Flows in the Chemicals and Materials Industry to Enable a Net-Zero Emissions Future

Adherence to the terms of the Paris agreement to limit the temperature rise, require shifting to net zero emissions within 1-3 decades and the deployment of negative C technologies thereafter. The ability to model the current and future state of emitting sectors is essential in this pursuit.

70% of all emitted GHGs are embodied in the products of chemicals and materials industry (CMI). ¹ Therefore, establishing a net-zero operation of the global CMI is of utmost importance in envisioning a net-zero world. Systematic methods of analyzing decarbonization pathways necessitate the compilation of data and models on current and emerging technologies in CMI. To this end, we extend on the recently developed C flow model for global CMI. ² We modify the model to map embodied C emissions, include data for emerging production technologies, calculate metrics to judge decarbonization potential of sectors, and illustrate the use of this framework for chemicals production in the US.

The C footprint of chemical products involves indirect as well as upstream emissions. While current research does analyze material flow under the adoption of various net-zero production alternatives, its effects on embodied C of products downstream remain largely unknown. ^3,4 For example, while electrolytic production of methanol may lower direct emissions, the total embodied emissions of methanol and products like formaldehyde that lie further downstream may increase depending on the C footprint of electricity used. ⁵ Moreover, current datasets consider only the transformation of resources to products, without distinguishing between multiple pathways of transformation. Thus, the complete network of processes is not represented, which leads to oversight of mitigation potential and miscalculation of emissions savings.

We use the previously developed C flow model to map the flow of embodied C through the network of processes within the chemical industry. ² Using this framework, we develop models of direct and life cycle carbon flows for the global and US CMI and describe how the approach may be used to develop similar models for other nations and for corporations. We also develop models of emerging technologies that are relevant to decarbonization on the input-side such as electrification of chemical processes or biomass-based feedstocks, output-side such as Carbon Capture, Utilization, and Storage (CCUS), and technologies that enable circularity. Finally, we calculate metrics such as carbon efficiency and carbon return on investment, to identify processes that could benefit most from decarbonization. The value addition to the economy is calculated under both conventional and emerging technologies, under the assumption that product prices do not change.

We use the LCA framework to model the chemical industry network at the process scale, at steady state. The transformation of products via processes, and resource use as well as emissions associated with the transformations, are represented as matrices. We outline an algorithm to calculate embodied C via allocation of resources and emissions, on the basis of C contained in useful products. Process data is compiled from life cycle inventories ^6,7, literature, government databases ⁸ and GHG inventories ⁹. Mass and energy balances, and stoichiometric information is used to reconcile missing data.

We represent the results of our analysis as Sankey diagrams showing C flows between natural resources and processes in the CMI. The resulting models provide the foundation for synthesizing net-zero networks, understanding the trade-offs between decarbonization and cost, and identifying areas that would benefit most from further work and innovation.

References

1. Circle Economy (2020) The circularity gap report
2. Sen, Amrita, George Stephanopoulos, and Bhavik Bakshi. "Mapping Anthropogenic Carbon Mobilization Through Chemical Process and Manufacturing Industries." PSE 2021+ Conference Proceedings (2022). https://pse2021.jp/
3. Gabrielli, P., Gazzani, M., & Mazzotti, M. (2020). The role of carbon capture and utilization, carbon capture and storage, and biomass to enable a net-zero-CO2 emissions chemical industry. Industrial & Engineering Chemistry Research, 59(15), 7033-7045.
4. Kätelhön, A., Meys, R., Deutz, S., Suh, S., & Bardow, A. (2019). Climate change mitigation potential of carbon capture and utilization in the chemical industry. Proceedings of the National Academy of Sciences, 116(23), 11187-11194.
5. Howarth, R. W., & Jacobson, M. Z. (2021). How green is blue hydrogen? Energy Science & Engineering, 9(10), 1676-1687.
6. Ecoinvent version 3.8. https://www.ecoinvent.ch Accessed 3 March 2022
7. United States Life Cycle Inventory (USLCI) https://www.nrel.gov/lci/ Accessed 9 Sept. 2021
8. Flowcharts- Lawrence Livermore National Laboratory https://www.flowcharts.llnl.gov/ Accessed 11 Sept 2021
9. United States Environmental Protection Agency https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks Accessed 3 March 2022