Three-step procedure for early-stage evaluation of CO2 utilization technologies based on TRLs.

The reduction of CO2${\rm CO}_{2}$ in an electrochemical reactor using electrical energy is a promising approach to implement a more sustainable carbon economy and to replace fossil fuels with renewable carbon sources. Conventionally used solid plate electrodes are limited by poor mass transport of the reactants. Gas diffusion electrodes (GDEs) can overcome this limitation and have gained industrial relevance during the last decades. A comprehensive understanding of transport and conversion phenomena within such porous electrodes is not yet well developed. Here, we report a one‐dimensional steady state model of the GDE to investigate the influence of relevant operational parameters and GDE properties on CO2${\rm CO}_{2}$ reduction. The results indicate the importance of controlling the local reaction environment, that is, the reactant concentration and the pH value, by tuning the electrolyte and gas composition, and flow rate as well as the catalyst layer properties.

Reducing carbon dioxide to value‐added chemicals by electrolysis is a promising strategy to substitute fossil‐based processes. Research on CO2 electrolysis has vastly progressed, focusing on catalysis and electrode design, leaving an essential question on the central part of the electrolyzer: Which type of ion exchange membrane is best suited for CO2 electrolysis from an economic perspective? To address this question, holistic process optimization of CO2 reduction and product purification is applied. The findings demonstrate that CO2 electrolysis with an anion exchange membrane shows competitive production costs for CO of 796 €/tCO, outperforming cation exchange and bipolar membranes. Unlike often described, the CO2 pumping effect does not significantly impair the economics but offers an efficient indirect regeneration of dissociated CO2. Furthermore, the results emphasize selective reduction of CO2 rather than co‐electrolysis of CO2 and H2O. While pointing to a positive economic perspective, life‐cycle assessment highlights the need to minimize CO2 emissions related to electricity consumption and incomplete CO2 utilization.