Towards the Electrochemical Conversion of CO2 to Formic Acid at an Applicative Scale: Technical and Economic Analysis of Most Promising Routes

Abstract

In the last decade, the electrochemical conversion of CO2 to formic acid, FA, using Sn-based cathodes, was widely investigated. In this work, the technical feasibility and economic viability of this process were evaluated considering the most promising electrochemical routes reported in the literature. Five case studies, based on the utilisation of gas diffusion electrode (GDE) technologies or high CO2 pressures, were analysed. The cost for producing FA by the electrochemical route was compared with that of the conventional chemical route. Several scenarios were envisioned finding the target figures of merit, the potential bottlenecks (including low FA concentration, GDE cost and high energy consumption) of each technology and the challenges that need to be faced. It was shown that the performances of these processes are not still adequate from an economic point of view and the improvements that should be achieved were identified. To be suitable for the commercialisation, the process should reach simultaneously high current density, faradaic efficiency and actual FA concentration as well as good stability with time and a limited cost of electrodes. In addition, it was shown that the utilisation of the excess electric energy generated from renewable sources could significantly reduce the costs of the process.