Proceedings of nanoGe Fall Meeting19 (NFM19)
DOI: https://doi.org/10.29363/nanoge.nfm.2019.287
Publication date: 18th July 2019
Electrochemical CO2 reduction is championed as a technology which will play a role in the global energy transition away from fossil fuels. Inherently, this implies that the technology will be scaled to large enough sizes to impact global energy consumption (~TW) and measurably offset carbon emissions. Given these prospects, an extremely large number of researchers have focused on developing new catalysts, novel devices and predicting the uses of CO2 electrolyzers within our society with the long-term goal of making the technology commercial. But what would this endgame for CO2 electrolyzers actually look like?
While electrochemical CO2 reduction is very much in its infancy, it is worthwhile to discuss what a commercial CO2 electrolyzer plant will necessarily look like if we are to succeed with our current lines of research. Specifically, given the need to capture CO2 prior to electrochemical conversion, up convert most CO2 reduction products, and operate on renewable electricity, it is essential that we start thinking about CO2 electrolyzers as part of a larger system, rather than as an independent technology. Such a back-of-the-envelope analysis provides valuable feedback to researchers at nano‑, micro- and macro-scales looking to understand and improve the technology, while providing constraints that can help eliminate untenable design options.
In this work, we consider the use of CO2 electrolyzers as one technology in the ‘air-to-barrel’ production of 10,000 tons methanol/day, the size of today’s mega plants. Looking at the role of the CO2 electrolyzers in the process, we highlight the distribution of energy resources required, the potential for process integration and the importance of increasing the current densities of CO2 electrolyzers even further. This analysis then allows us to determine the physical scales of solar panels, direct air capture units and CO2 electrolyzer catalyst area that will be needed to run a plant in the future. A key conclusion finds that a 6 order-of-magnitude gap exists between catalyst areas in current CO2 electrolyzers and industry-sized applications, emphasizing the need to begin research on scaling CO2 catalysts and electrolyzers immediately if they are to contribute in the timeframe needed for the upcoming energy transition.