Modeling atmospheric impacts of amine emissions from post-combustion carbon capture systems

• A photochemical puff model, SCICHEM, to simulate the impacts of air emissions associated with amine-based post-combustion CO 2 capture (PCCC) at hypothetical natural gas combined cycle and coal-fired power plants. • Atmospheric chemistry of monoethanolamine (MEA), 2-amino-2-methylpropanol (AMP) and piperazine (PZ) was added to the model in addition to its current photochemical mechanism. • Three representative amine solvents (PZ, MEA, and CESAR 1, a blend of PZ and AMP) were studied, and configurations with water wash and with acid wash were used in the modeling. • The results show that with water wash, the long-term annual average air concentrations of nitrosamines + nitramines for all three solvents are well below the exposure limit established by the Norwegian Institute of Public Health (NIPH) but short-term exposures may exceed this limit. • Using acid wash resulted in significant reductions in nitrosamine + nitramine concentrations, as well as in total fine particulate matter (PM2.5). This paper describes the application of a photochemical puff model, the Second-Order Closure Integrated Puff Model with Chemistry (SCICHEM), to simulate the impacts of air emissions associated with amine-based post-combustion CO 2 capture. Amines react in the atmosphere with the hydroxyl (OH) radical and other oxidants to form potentially harmful products, such as nitrosamines and nitramines. Amines can also form particles with sulfuric acid that may be present in the amine absorber or in the atmosphere. Nitrosamines can photolyze back to the amino radical. Simulating these processes requires the use of a photochemical model that can provide concentrations of the oxidants that influence amine chemistry. In this work, SCICHEM was adapted to include the chemistry of three amines: monoethanolamine (MEA), 2-amino-2-methylpropanol (AMP) and piperazine (PZ). These solvents were chosen since more thermodynamic and kinetic data are available for these amines than for other proprietary amines. The model was applied to the Midwest and Gulf Coast regions in the United States to evaluate the air quality impacts of amine-based post-combustion carbon capture (PCCC) systems applied to natural gas combined cycle (NGCC) and coal-fired power plants. Three representative amine solvents (PZ, MEA, and CESAR 1, a blend of PZ and AMP) were studied, and configurations with water wash and with acid wash were used in the modeling. The results show that with water wash, the long-term annual average air concentrations of nitrosamines + nitramines for all three solvents are well below the exposure limit of 0.3 ng/m 3 established by the Norwegian Institute of Public Health (NIPH). However, the 98 th percentile of the 24 h averages of nitrosamine + nitramine are above the exposure limit, indicating some health concern from short-term exposure. Using acid wash resulted in significant reductions in nitrosamine + nitramine concentrations, as well as in total PM 2.5 . For PZ and MEA, using acid wash reduced the peak 24 h and 98 th percentile 24 h nitrosamine + nitramine concentrations to below the limit. However, for some of the CESAR 1 solvent scenarios, the threshold is still exceeded when acid wash is used.