The production of base chemicals by electrochemical conversion
of captured CO2has the potential to close the carbon cycle,
thereby contributing to a future energy transition. With the feasibility
of low-temperature electrochemical CO2conversion demonstrated
at lab scale, research is shifting toward optimizing electrolyser
design and operation for industrial applications, with target values
based on techno-economic analysis. However, current techno-economic
analyses often neglect experimentally reported interdependencies of
key performance variables such as the current density, the faradaic
efficiency, and the conversion. Aiming to understand the impact of
these interdependencies on the economic outlook, we develop a model
capturing mass transfer effects over the channel length for an alkaline,
membrane electrolyser. Coupling the channel scale with the higher
level process scale and embedding this multiscale model in an economic
framework allows us to analyze the economic trade-off between the
performance variables. Our analysis shows that the derived target
values for the performance variables strongly depend on the interdependencies
described in the channel scale model. Our analysis also suggests that
economically optimal current densities can be as low as half of the
previously reported benchmarks. More generally, our work highlights
the need to move toward multiscale models, especially in the field
of CO2electrolysis, to effectively elucidate current bottlenecks
in the quest toward economically compelling system designs.