Planetary Boundaries Assessment of Flue Gas Valorization into Ammonia and Methane

Abstract

Carbon capture and utilization (CCU) has attracted growing interest to potentially curb CO 2 emissions while generating valuable chemicals. These emerging technologies will coexist with their fossil analogs soon, creating opportunities to combine both. In this context, flue gas valorization from power plants can play a role in this transition. The success of CCU technologies will ultimately depend on its environmental sustainability, which should be evaluated based on global indicators such as the Planetary Boundaries (PBs). Here we assessed the absolute sustainability level of an integrated facility producing ammonia (NH 3 ) and synthetic natural gas (SNG) using hydrogen (H 2 ) from water electrolysis, and nitrogen (N 2 ) and CO 2 from flue gas from a combined-cycle natural gas power plant. The LCA-PBs assessment showed that the alternative technologies could contribute to operating the Planet safely by significantly reducing the impact on the climate change and ocean acidification Earth-system processes, compared to the fossil Haber-Bosch (HB) and conventional steam reforming processes. Overall, the investigated process could smoothen the transition towards low-carbon technologies. More broadly, the application of the PBs to quantify the environmental performance of the integrated system opens up new avenues for the absolute sustainability assessment of emerging low-carbon technologies within the chemical sector and beyond.