Modelling and Analysis of CO2 Electrolyzers Integrated with Downstream Separation Processes via Heat Pumps

The electrification of chemical processes and carbon capture and utilisation represent two promising approaches to improve efficiency and decrease carbon emissions of the process industry. The development of electrolyzers has gathered momentum in the last decades, allowing for the possible introduction of renewable electrons into carbon dioxide-based chemicals manufacture. While the performance of the electrolyzers is subject to improvements driven by the experimental community, the generation of waste heat is unavoidable due to the electrical resistances and process inefficiencies within the electrochemical cells. The possibility of re-using this waste heat has not been investigated within the realm of carbon dioxide electrolyzers. Here we show the potential of upgrading this waste heat by means of a heat pump, for its utilisation in the downstream processing of formic acid obtained from carbon dioxide electroreduction. We found that the waste heat represents roughly 62% of the power input to the electrochemical cells and it can be upgraded from 35 �C to 112 �C to drive the extractive distillation of formic acid and water. For a system producing 25 kt/y of formic acid, this results in the electrification of 60% of the separation energy duty, yielding a decrease in carbon dioxide emissions of 39-58% for the downstream processing, while the addition of a heat pump has a payback period of ~4.4 years in the base case.