This article presents an ex ante life cycle assessment (LCA) of formic acid (FA) production on an industrial scale via the electrochemical reduction (ECR) of biogenic CO2 sourced from the incineration of wastewater sludge. Because renewable intermittent electricity is not suitable for continuous production and may be regulated by the EU, we model large-scale ECR-FA production using various power supply configurations, for example, by using the projected renewable electricity surplus for Germany in 2050 on an hourly resolution. The ECR-FA systems are compared to fossil-based FA production by using the 2020 and 2050 grid electricity mixes for Germany. Our LCA findings indicate that the most favorable system configuration in 2050 involves intermittent production with surplus renewable electricity, reducing GHG emissions by up to 83% relative to fossil FA, and also resulting in lower impacts than production with integrated battery storage or grid electricity. The main environmental impacts of ECR-FA production stem from the electricity demand in electrochemical conversion and purification. A cleaner electricity mix from 2020 to 2050 reduces climate impacts and nonrenewable energy use, yet it increases mineral and metal depletion. The materials used in the building of the electrolytic unit have a low environmental impact compared to the energy demands of electrolysis and purification. Future renewable grid power should be considered a constrained resource in the design of the upscaling of ECR technologies.
Nickel et al. (Wed,) studied this question.