(432a) Systematic Assessment of Alternative Low-Carbon Ethylene Production Pathways

Widely used as an essential building block for making resins and plastics, ethylene is a key platform chemical with a relatively large carbon footprint and production concentrated in the United States, Middle East, and China. Today, ethylene is manufactured through steam-cracking of ethane and naphtha, which has CO₂ emissions of 1~1.6 tonne (t) per t of ethylene. As material demand for ethylene is anticipated to increase with economic growth in various regions, there is an urgency to develop and deploy sustainable production routes and avoid “emissions lock-in” from the deployment of existing production routes. Possible options under consideration include: a ) direct electrification to substitute fossil fuel for heating during steam cracking, b) use of low-carbon hydrogen to provide heat for the cracking process, where the hydrogen is produced via alternative approaches including byproduct methane reforming with carbon capture and storage (CCS), c) dehydration of ethanol produced from sustainably available biomass resources as well as d) less mature, but potentially transformative approaches based on electrochemical conversion of ethane or methane. These technological options span alternative feedstocks, novel interactions with the other energy infrastructure, like the electricity grid and hydrogen infrastructure, and have different scaling properties, which must be considered when performing a comparative analysis.

The objective of this work is to perform a systematic techno-economic and environmental analysis of alternative low-carbon ethylene production routes that consider the above-mentioned factors. Our approach is based on: a) developing detailed process simulations for each process to allow for characterizing mass and energy balances and unit sizing, b) techno-economic analysis (TEA) to compare the cost and economic risks of each process according to various types of energy system interactions and c) life cycle analysis (LCA) to quantify the greenhouse gas (GHG) emissions impact spanning cradle-to-gate system boundary, that considers co-product disposition and energy infrastructure interactions. The results will provide insights for research and development teams and industry stakeholders by identifying key process drivers that will help reduce costs, emissions, and investment risks for each process.