Health risk analysis of nitrosamine emissions from CO2 capture with monoethanolamine in coal-fired power plants

• Nitrosamine emissions during CO2 capture process were reviewed.
• Health risks, namely, dimethylnitrosamine and diethylnitrosamine were assessed.
• Tolerant exposure concentration was calculated under 10−4 and 10−6 risks.
• The safety distances for the five scenarios were investigated.

Monoethanolamine (MEA)-based chemical absorption is extensively used in the capture processes of coal-fired power plants from flue gas. However, chemical carcinogens, such as nitrosamine, are released during MEA degradation, especially at the top of the absorber. This study analyzed five CO2 capture power plants with various capacities, and investigated nitrosamine exposure concentration at downwind direction. Tolerant exposure concentration was calculated under 10−4 and 10−6 risks during the health risk assessment. Safety distances D′ for the five scenarios (365, 3000, 40,000, 146,000, and 1,000,000 t/a) were calculated as first screening under the typically meteorological conditions over North China Plain (mixing height 1000 m, wind speed 5 m/s measured at reference anemometer height of 10 m, and atmospheric stability D). The emission rate and discharge height will affect the safety distance D′. When nitrosamines are directly emitted from absorber, the values D′ are 0, 0, 0, 1580, and 5700 m based on 10−6 risks. When nitrosamines are emitted from stacks of power plant, the health risks of nitrosamines can be negligible. Although the results were very uncertain, the health effects of nitrosamine emissions should be concerned and further studies are necessary to thoroughly investigate the emission rate of nitrosamines.