Scale-Dependent Techno-Economic Analysis of CO₂ Capture and Electroreduction to Ethylene

Abstract

The decarbonization of the chemical industry is essential to mitigate carbon dioxide (CO2) emissions. Ethylene (C2H4) is the highest production petrochemical globally. When powered by renewable electricity, the electrochemical conversion of CO2 to C2H4 offers a promising route to low carbon C2H4 production. We perform a detailed techno-economic assessment (TEA) of the CO2 reduction reaction (CO2RR) process, converting CO2 from an industrial point source to polymer-grade C2H4. We pair the CO2 electrolyzer with industrially mature upstream and downstream separation technologies in an Aspen Plus model. This comprehensive approach enables us to assess the valorization of both gas and liquid byproduct streams at commercial specification and assess the viability of these processes as a function of scale. We demonstrate that a minimum plant size of ∼3,000 tonne C2H4/year is needed to achieve economies of scale among the upstream and downstream processes. This minimum plant size is ∼200-fold smaller than that of conventional C2H4 plants, coincides with that of typical utility-scale solar installations (∼25 MW), and could enable a more distributed model of chemical production going forward. We further highlight technical and economic enablers that would increase the profitability of the CO2RR to C2H4 technology.

From CO2 to Sustainable Aviation Fuel: Navigating the Technology Landscape

“…Nevertheless, the ethanol in the cathodic liquid product stream could be further separated and dehydrated to form C 2 H 4 , which could then be fed into the oligomerization process to enhance the yield of C 8 –C 16 hydrocarbons produced by this route. Ethanol can be separated with an approximately 95 wt % purity via double- or triple-column extractive distillation from the azeotropic mixture of H 2 O, CH 3 COOH, and CH 2 O 2 . ,− This is followed by ethanol dehydration to produce C 2 H 4 . Ethanol dehydration is a mildly endothermic reaction (Δ H 0 = 45.6 kJ/mol) that can be catalyzed by acid-based catalysts such as silica and alumina .…”

“…This technology is still in an early stage of development, with low TRL. However, it has been reported that enhancing certain short-term technical and economic factors could make direct CO 2 electrolysis a more profitable method for C 2 H 4 production . Therefore, the pathway through the C 2 H 4 intermediate produced by direct CO 2 electrolysis is also compelling and, thus, selected for further investigation.…”

A simple evaluation of adiabatic proton tunneling across the electrified double layer

“…[1][2][3] Such reactions can facilitate more sustainable routes for chemical transformations, potentially reducing the carbon footprint associated with processes related to climate change mitigation efforts. [4][5][6][7] Identifying rate-limiting steps for processes involving CPET steps remains a key challenge to elucidating the complexities of proton transfer processes and improving existing chemical transformation technologies. 3,[8][9][10][11] Recent advancements in electrocatalysis theory and developments in methods for density functional theory (DFT) have revolutionized our understanding of CPET reactions at the atomic level.…”

A Simple Evaluation of Adiabatic Proton Tunneling across the Electrified Double Layer

“…Coupled Proton–Electron Transfer (CPET) reactions are a fundamental process where a proton and an electron are transferred simultaneously in a single kinetic step. − Such reactions can facilitate more sustainable routes for chemical transformations, − potentially reducing the carbon footprint associated with processes critical to climate change mitigation efforts. Identifying and reducing rate-limiting steps for processes involving CPET steps remains a key challenge toward improving existing chemical transformation technologies. ,− Recent advancements in electrocatalysis theory and developments in methods for density functional theory (DFT) have revolutionized our understanding of CPET reactions at the atomic level. ,− These developments have not only provided fundamental insights into reaction dynamics but also improved our ability to predict trends in their rates more accurately, a crucial step toward optimizing the use of such processes in energy conversion and storage.…”