Global warming footprint of the electrochemical reduction of carbon dioxide to formate

Carbon dioxide Capture and Storage (CCS) is an important technological option for climate change mitigation. Utilization (U) of this captured CO2 as raw material for Electrochemical Reduction (ER) has been suggested as a valorization option to produce organics such as formate-based products. Previous work has focused on the influence of operating conditions or the selected cathodic material on the faradaic efficiency and distribution of products. The environmental sustainability of formate production through the ER of CO2 has been assumed rather than investigated. In this study, we perform a life cycle assessment, focusing on resources and greenhouse gas (GHG) emissions. Even though the processes reported in the literature result in a wide range of GHG emissions for the ER of CO2 to formate-based products from 32 to 519 kg CO2-eq.·(kg HCOO−)−1, this is higher than the current commercial production processes (3.1 kg CO2-eq.·(kg HCOO−)−1). The consumption of chemicals by the electrolysis and of steam in the purification of the final formate products are found to be the dominant causes of environmental burdens of the integrated process. A future scenario under very optimistic conditions suggests 0.33 kg CO2-eq.·(kg HCOO−)−1 thus presenting a potential pathway to an environmentally sustainable CO2 utilization option.