Scale-Dependent Techno-Economic Analysis of CO<sub>2</sub> Capture and Electroreduction to Ethylene
Théo Alerte, Adriana Gaona, Jonathan P. Edwards, Christine M. Gabardo, Colin P. O’Brien, Joshua Wicks, Loann Bonnenfant, Armin Sedighian Rasouli, Daniel Young, Jehad Abed, Luke Kershaw, Yurou Celine Xiao, Amitava Sarkar, Shaffiq A. Jaffer, Moritz W. Schreiber, David Sinton, Heather L. MacLean, Edward H. Sargent
Abstract
The decarbonization of the chemical industry is essential to mitigate carbon dioxide (CO 2 ) emissions. Ethylene (C 2 H 4 ) is the highest production petrochemical globally. When powered by renewable electricity, the electrochemical conversion of CO 2 to C 2 H 4 offers a promising route to low carbon C 2 H 4 production. We perform a detailed techno-economic assessment (TEA) of the CO 2 reduction reaction (CO 2 RR) process, converting CO 2 from an industrial point source to polymer-grade C 2 H 4 . We pair the CO 2 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 C 2 H 4 /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 C 2 H 4 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 CO 2 RR to C 2 H 4 technology.