Development of electrochemical reactors for CO2 electroreduction-the viability of an electrochemical CO2 plant in Brazil

Abstract

Our global economy based on burning fossil fuels reached a turning point in the 2020s as problems arising from climate change are becoming increasingly evident. An important strategy to decrease anthropogenic CO2 emission relies on carbon capture and storage (CCS). However, the challenges associated with long-term storage of CO2 in the gas phase highlight the need for a viable Chemical Fixation of CO2. In this scenario, electrochemistry gains prominence since electricity from renewable sources can provide the electrons needed for CO2 electroreduction. The main drawback is the high stability of CO2, the most oxidized form of carbon. Our intention in this Perspective is to give a concise overview of CO2 electroreduction, focusing on why working in the gas phase may help overcome mass transport limitations due to the low solubility of CO2 and how the chemical environment can affect selectivity and activity. We also explore a carbon-emission analysis applied to a CO2 electrochemical system. To do so, we assumed a Brazilian scenario, that is, the carbon footprint associated with electricity generation in the country. Since Brazil relies on more renewable energy sources, an electrochemical reactor that converts CO2 to oxalate with a conversion efficiency (CE) of 20% is enough to result in CO2 abatement, that is, an oxalate production with a negative carbon footprint. Compared with the United States of America, such a system would need to operate at higher CE, 50%, to produce similar results. These results evidence how intricate the implementation of an electrochemical plant is with the carbon footprint of the electricity source.