Economic analysis of atmospheric mercury emission control for coal-fired power plants in China.

Coal combustion and mercury pollution are closely linked, and this relationship is particularly relevant in China, the world's largest coal consumer. This paper begins with a summary of recent China-specific studies on mercury removal by air pollution control technologies and then provides an economic analysis of mercury abatement from these emission control technologies at coal-fired power plants in China. This includes a cost-effectiveness analysis at the enterprise and sector level in China using 2010 as a baseline and projecting out to 2020 and 2030. Of the control technologies evaluated, the most cost-effective is a fabric filter installed upstream of the wet flue gas desulfurization system (FF+WFGD). Halogen injection (HI) is also a cost-effective mercury-specific control strategy, although it has not yet reached commercial maturity. The sector-level analysis shows that 193 tons of mercury was removed in 2010 in China's coal-fired power sector, with annualized mercury emission control costs of 2.7 billion Chinese Yuan. Under a projected 2030 Emission Control (EC) scenario with stringent mercury limits compared to Business As Usual (BAU) scenario, the increase of selective catalytic reduction systems (SCR) and the use of HI could contribute to 39 tons of mercury removal at a cost of 3.8 billion CNY. The economic analysis presented in this paper offers insights on air pollution control technologies and practices for enhancing atmospheric mercury control that can aid decision-making in policy design and private-sector investments.

Radon natural radioactivity measurements for evaluation of primary pollutants.

Radon is naturally released from the soil into the surface layer of the atmosphere, and by monitoring the natural radioactivity data of radon and its shot-live decay products we can get valuable information about the dilution properties of the lower boundary layer. This paper explores the dispersion characteristics of the lower layer of the atmosphere in Lanzhou, China, and the close relationship with the patterns of primary pollutants' concentrations. Measurements were conducted from July 2007 to May 2008 at one station and a fifty-day campaign was carried out at two stations in Lanzhou. The interpretation of radon radioactivity measurement showed that the measured atmospheric stability index (ASI) data at two stations in Lanzhou had statistically significant correlation, and well described the lower atmospheric layer mixing property in the area. The temporal trend of PM10 data was consistent with the temporal trend of ASI, with almost twice as high values in December than it in August. The results show that the ASI allows to highlight the dilution factor playing an important role in determining primary pollution events, and the mixing properties of the lower boundary layer is the key factor determining PM10 concentration in urban areas.

Synergistic mercury removal by conventional pollutant control strategies for coal-fired power plants in China.

China's 11th 5-yr plan has regulated total sulfur dioxide (SO2) emissions by installing flue gas desulfurization (FGD) devices and shutting down small thermal power units. These control measures will not only significantly reduce the emission of conventional pollutants but also benefit the reduction of mercury emissions from coal-fired power plants. This paper uses the emission factor method to estimate the efficiencies of these measures on mercury emission abatement. From 2005 to 2010, coal consumption in power plants will increase by 59%; however, the mercury emission will only rise from 141 to 155 t, with an increase of 10%. The average emission rate of mercury from coal burning will decrease from 126 mg Hg/t of coal to 87 mg Hg/t of coal. The effects of the three desulfurization measures were assessed and show that wet FGD will play an important role in mercury removal. Mercury emissions in 2015 and 2020 are also projected under different policy scenarios. Under the most probable scenario, the total mercury emission in coal-fired power plants in China will decrease to 130 t by 2020, which will benefit from the rapid installation of fabric filters and selective catalytic reduction.