Environmental system analysis on formic acid synthesis from captured CO₂and green H₂using life cycle assessment methodology

Hydrogen (H2) is highly promising as an alternative energy source because it does not emit CO2 when used; thus, H2 utilization is a potential solution to fossil fuel depletion and global warming. In our previous studies, green H2 was developed through biomass pyrolysis. Meanwhile, the development of carbon dioxide capture utilization technologies to recycle CO2 gas from fossil fuel is being considered. Moreover, formic acid (FA) synthesis is among the candidate procedures for utilizing captured CO2. FA is a vital chemical substance with numerous industrial applications. As the simplest carboxylic acid, FA produces various chemical products. The demand for FA will continue to increase, mainly due to recent technological advancements in fuel cells and renewable energy. The primary pathway for FA synthesis involves the hydrolysis of fossil fuel-derived formic acid methyl. In this study, we investigated FA synthesis using CO2 from fossil fuel and green H2 from biomass as raw materials. Subsequently, we evaluated the environmental impact of the synthesized FA compared with the conventional fossil fuel-derived FA by applying the life cycle assessment methodology. The evaluation focuses on Japan, aiming to reduce environmental impact as an evaluation metric while considering the constraints on CO2 emissions and H2 production scale. Furthermore, we sought to identify the conditions that would reduce the environmental impact of FA synthesis.