Uncertainties in estimating mercury emissions from coal-fired power plants in China

Abstract

Abstract.A detailed multiple-year inventory of mercury emissions from anthropogenic activities in China has been developed. Coal combustion and nonferrous metals production continue to be the two leading mercury sources in China, together contributing ∼80% of total mercury emissions. However, many uncertainties still remain in our knowledge of primary anthropogenic releases of mercury to the atmosphere in China. In situations involving large uncertainties, our previous mercury emission inventory that used a deterministic approach could produce results that might not be a true reflection of reality; and in such cases stochastic simulations incorporating uncertainties need to be performed. Within our inventory, a new comprehensive submodule for estimation of mercury emissions from coal-fired power plants in China is constructed as an uncertainty case study. The new sub-module integrates up-to-date information regarding mercury content in coal by province, coal washing and cleaning, coal consumption by province, mercury removal efficiencies by control technology or technology combinations, etc. Based on these detailed data, probability-based distribution functions are built into the submodule to address the uncertainties of these key parameters. The sub-module incorporates Monte Carlo simulations to take into account the probability distributions of key input parameters and produce the mercury emission results in the form of a statistical distribution. For example, the best estimate for total mercury emissions from coal-fired power plants in China in 2003 is 90.5 Mg, with the uncertainty range from 57.1 Mg (P10) to 154.6 Mg (P90); and the best estimate for elemental mercury emissions is 43.0 Mg, with the uncertainty range from 25.6 Mg (P10) to 75.7 Mg (P90). TheCorrespondence to: Y. Wu (ywu@tsinghua.edu.cn) results further indicate that the majority of the uncertainty in mercury emission estimation comes from two factors: mercury content of coal and mercury removal efficiency.

Impacts of the Minamata Convention on Mercury Emissions and Global Deposition from Coal-Fired Power Generation in Asia

“…To estimate the impact of technology choices on emissions, we combine assumptions about the mercury removal efficiency and speciation effects of technologies with projections for future coal use. Following Streets et al 15,26 and Wu et al, 27 we calculate total mercury emissions from CFPPs in a given region as…”

“…Conventional coal cleaning targeting ash (which lowers the energy value of coal and combustion efficiency of boilers) and sulfur can also reduce mercury content by ∼30%. 24,27,47,48 However, a wide range of removal efficiencies has been reported (0−78%), as efficacy depends on coal source and characteristics. 24,27,47,48 Coal blending, additives, and beneficiation are discussed in the SI.…”

“…24,27,47,48 However, a wide range of removal efficiencies has been reported (0−78%), as efficacy depends on coal source and characteristics. 24,27,47,48 Coal blending, additives, and beneficiation are discussed in the SI.…”

Anthropogenic atmospheric nickel emissions and its distribution characteristics in China

“…In this study, Monte Carlo simulation is used to quantify the uncertainties in the anthropogenic atmospheric Ni emission inventory based on available activity data and emission factors distribution. Most of the input parameters of activity levels and emission factors, with corresponding statistical distribution, are determined depended on the authors' judgment, or referred to the related references (Wu et al, 2010;Zhao et al, 2010;. Table 6 shows the uncertainties (95% confidence interval around the arithmetic mean value) in Chinese anthropogenic atmospheric Ni emissions by sectors in 2009.…”

Characteristics of Mercury Emissions from a Coal-fired Power Plant

“…Specifically, there are lacking actual measurements of Hg emission rates, Hg species profiles from Chinese combustors and the capture of Hg in Chinese emission control devices [10]. There are even higher uncertainties for the speciation profiles.…”