Amine scrubbing for CO2 capture generates carcinogenic nitrosamine emissions

The dominant commercial technology for post-combustion carbon capture uses aqueous amine solvents (typically monoethanolamine or MEA) to absorb CO2 from flue gas. When these amines react with NOx compounds in the flue gas, they produce nitrosamines -- a class of compounds classified as probable human carcinogens. A pilot study at a waste-to-energy plant found measurable amine and nitrosamine emissions in the treated gas exiting the capture system. Plant operators face an impossible bind: they need to demonstrate carbon capture to qualify for 45Q credits and meet emissions targets, but operating the capture system may trigger additional air quality permit requirements, community opposition, and potential liability for a new category of hazardous air pollutant. This matters because nitrosamine formation scales with capture volume -- the more CO2 you capture, the more nitrosamines you produce -- creating a perverse tradeoff between climate goals and local air quality. The problem persists because eliminating NOx from flue gas before it reaches the amine scrubber adds cost and complexity (requiring additional SCR/SNCR systems), and alternative non-amine solvents that avoid nitrosamine formation are not yet commercially proven at scale.