Atmospheric emission inventory of SO3 from coal-fired power plants in China in the period 2009-2014

Sulfur trioxide (SO3) pollution is becoming another severe problem in coal-fired power plants after SO2, NOx, and PM, however, the characteristics of SO3 emission in China remains unclear. In this paper, we established a refined activity data, and summarized the removal efficiency of different control technologies according to the literature review and field test results. An emission inventory of SO3 from coal-fired power plants in China between 2009 and 2014 was developed, which indicated the SO3 emission increased from 199.7 kilotons (kt) to 314.6 kt at an average annual growth rate of 9.7%. The results show that Neimenggu, Shanxi, Jiangsu, Shandong, Guangdong and Guizhou were the largest emitters, accounting for 49.7% of the total SO3 emissions in 2014. We analyzed the historical data with ArcGIS system, which allocates the emission into 36 km x 36 km grid cells. In addition, the result shows the unevenly spatial distribution. Combined with future economic development as well as implementation of policy, three different scenarios were set to project SO3 emission in coal-fired power plants in 2020, which represented the potential of SO3 emission reduction. Compared with scenario A, SO3 emission can be reduced to 83.9 kt in scenario B, and in scenarios C, SO3 emission can be reduced to 38.4 kt. Coal-fired power plants should adopt different technology routes to meet the ultra-low emission requirement and reduce the SO3 emission according to the boiler type, sulfur content, and the emission standard.