Recycling of waste CO₂ to bulk chemicals has a tremendous potential for the decarbonization of the chemical industry. Quantitative analysis of the prospects of this technology is hindered by the lack of flexible techno-economic assessment (TEA) models that enable evaluation of the processing costs under different deployment scenarios. In this protocol, we explain how to convert literature data into metrics useful for evaluation of the emerging electrolysis technologies, derive TEA models, and illustrate their use with a CO₂-to-ethylene example. For complete details on the use and execution of this protocol, please refer to Barecka et al. (2021a).

The chemical industry needs to significantly decrease carbon dioxide (CO₂) emissions in order to meet the 2050 carbon neutrality goal. Utilization of CO₂ as a chemical feedstock for bulk products is a promising way to mitigate industrial emissions; however, CO₂-based manufacturing is currently not competitive with the established petrochemical methods and its deployment requires creation of a new value chain. Here, we show that an alternative approach, using CO₂ conversion as an add-on to existing manufactures, can disrupt the global carbon cycle while minimally perturbing the operation of chemical plants. Proposed closed-loop on-site CO₂ recycling processes are economically viable in the current market and have the potential for rapid introduction in the industries. Retrofit-based CO₂ recycling can reduce annually between 4 and 10 Gt CO₂ by 2050 and contribute to achieving up to 50% of the industrial carbon neutrality goal.

Electrosynthesis of ethanol from carbon dioxide (CO2) is a promising route to generate a sustainable fuel and a convenient feedstock for chemical manufacturing. While significant progress has been achieved in boosting the selectivity of CO2 to ethanol, the subsequent ethanol separation remains a bottleneck, which prevents leveraging the laboratory results into large-scale systems. Here we report vacuum membrane distillation as a method that efficiently concentrates dilute ethanol streams produced by CO2 electrolysis (CO2R), yielding up to ∼40 wt% ethanol in pure water. In our design considerations, we include previously underappreciated thermodynamic properties of the catholyte (salting-out effect) and propose strategies allowing a more precise estimation of energy inputs to the separation processes. Our work provides the basis for the detailed design of complex systems which integrate flow reactors and liquid separations and supports scaling of the systems previously considered not optimized for industrial use.