A Highly Resolved Mercury Emission Inventory of Chinese Coal-Fired Power Plants

As the largest coal consumer in China, the coal-fired power plants have come under increasing public concern in regard to atmospheric mercury pollution. This study developed an up-to-date and high-resolution mercury emission inventory of Chinese coal-fired power plants using a unit-based method that combined data from individual power plants, provincial coal characteristics, and industry removal efficiencies. National mercury emissions in 2015 were estimated at 73 tons, including 54 tons of elemental mercury, 18 tons of gaseous oxidized mercury and 1 ton of particle-bound mercury. Pulverized coal boilers emitted 65 tons, mainly in the coastal provinces and coal-electricity bases. Circulating fluidized bed boilers emitted 8 tons, mainly in Inner Mongolia and Shanxi Province. The average mercury emission intensity over the Chinese mainland was 18.3 g/GWh, which was similar to the limit for low-rank coal-fired units in the United States. The overall uncertainty of national mercury emission was estimated to be -19% to 20%, with the mercury content in coal being the major contributor. In most provinces, monthly mercury emissions generally peaked in December and August. However, monthly partition coefficients of southwest China were obviously lower than other regions from June to October due to the high proportion of hydropower generation.