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China’s Air Pollution Control Calls for Sustainable Strategy for the Use of Coal Jinnan Wang, Yu Lei,* Jintian Yang, and Gang Yan Key Laboratory of Environmental Planning and Policy Simulation, Chinese Academy for Environmental Planning, Beijing 100012, China indicated that a minimum of 10 million metric tons (MMT) reductions of SO2 and NOX emissions is needed in China to avoid air quality nonattainment.4 Most emissions of air pollutants in China are associated with coal consumption. In 2010 China contributed 48% of global coal consumption. Coal consumed in China, including those burned in the boilers and used in the kilns, accounted for more than 90%, 70%, and 60% of national-wide emissions of SO2, NOX, and primary PM10, respectively. There is no alternative for China except to significantly reduce emissions from coal consumption in order to improve air quality. End-of-pipe technologies have always been the top choice in China to abate emissions from boilers and kilns. For example, great efforts have been made to promote flue gas desulfurization (FGD) in order to hit the 10% reduction target of SO2 emissions over 2005−2010. The penetration rate of FGD in Chinese thermal power plants increased from 12% in 2005 to 82% in 2010. The significant growth of FGD resulted in a 29% reduction of SO2 emissions, from 13.5 MMT in 2005 to 9.6 hina has achieved 14% reduction of sulfur dioxide (SO2) MMT in 2010, despite a 50% increase of coal consumption in emissions over 2005−2010 in spite of 35% growth in coal power sector. Since installation of FGD has shown great use. However, emissions of air pollutants in China, including effectiveness in reducing SO2 emissions, some other end-ofSO2, nitrogen oxides (NOX) and particulate matters (PM), are pipe technologies, such as selective catalytic reduction (SCR) still twice as high as those in the United States (Table 1). and selective noncatalytic reduction (SNCR), have been recognized as promising options to achieve 10% reduction of Table 1. Comparison of Area, Emissions and Coal NOX emissions over 2010−2015. Consumption in 2010 between China and U.S.a Despite the great success and prospects of the end-of-pipe b c technologies in emissions reduction, China is still facing critical China U.S. challenges to address the emissions from coal consumption. area (million square kilometer) 9.6 9.8 The first one is the increasing coal consumption in the near SO2 emissions (million metric tons) 21.9 8.6 future. China’s annual coal consumption increased from 1.4 NOX emissions (million metric tons) 22.7 12.4 billion metric tons (BMT) in 2000 to 3.1 BMT in 2010. PM10 emissions (million metric tons) 18.8 10.2 Another 1 BMT increment is expected in the next 5 years, if the coal consumption (million metric tons oil equivalent)d 1713.5 524.6 a energy intensive industries, such as cement, iron and steel Emissions of PM10 in China is estimated for 2005, derived from Lei et making, maintain rapid growth. The second challenge lies in al., 2011.1 bSO2 and NOX emissions data of China is from Chinese limited potential from the end-of-pipe technologies. Success of official statistics cEmissions data of U.S. is from U.S. Environmental Protection Agency’s National Emissions Inventory dCoal consumption SO2 emissions control over 2005−2010 is attributed to rapid data is from BP’s statistic of world energy 2011. growth of FGD. However, there is only 10% of existing power units left for FGD installation. New approaches have to be applied to achieve further reductions. The third challenge Substantial emissions lead to severe air pollution. The annual comes from the small and dispersed emission sources. To date average PM10 concentration of Chinese cities is 5 times as high there are approximately 500 000 industrial boilers in China, 2 as the World Health Organization’s guideline. The satellite consuming 0.6 BMT coal annually. Smaller coal-fired boilers observation indicates that the PM2.5 concentration in some 33 tend to be technically infeasible and economically incapable of regions could be as high as 90 μg/m , which is 1 order of magnitude higher than that in most cities in the United States Received: March 28, 2012 and Europe. Therefore, emissions of primary PM and the precursors of secondary PM, such as SO2 and NOX, have to be Accepted: April 3, 2012 Published: April 6, 2012 considerably reduced to improve air quality. Some study has
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dx.doi.org/10.1021/es301226n | Environ. Sci. Technol. 2012, 46, 4263−4264
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(2) World Health Organization (WHO). 2011. Database: outdoor air pollution in cities; http://www.who.int/phe/health_topics/ outdoorair/databases/en/index.html (accessed March 18, 2012). (3) van Donkelaar, A; Martin, R. V; Brauer, M; Kahn, R; Levy, R; Verduzco, C; Villeneuve, P. J. Global estimates of ambient fine particulate matter concentrations from satellite-based aerosol optical depth: development and application. Environ. Health Perspect. 2010, 118 (6), 847−855. (4) Pu, H, Eds. Sustainable Development and Utilization of Coal and the Environmental Implications; University of Mining and Technology Press: Beijing, China, 2010 (in Chinese). (5) U.S. Energy Information Administration (USEIA). Annual Energy Review; http://www.eia.gov/totalenergy/data/annual/ showtext.cfm?t=ptb0703 (accessed March 18, 2012).
deploying advanced emission control technologies. In addition, emissions from the dispersed boilers are hard to be supervised. To address the above challenges, a sustainable strategy on coal consumption has to be highlighted in China. First of all, a cap of coal consumption needs to be considered. Chinese government has set ambitious national target for emissions control of SO2 (8% reduction) and NOX (10% reduction) over 2010−2015. Although the mandatory target demonstrates Chinese central government’s resolution, the local government’s desire for economy’s development always encourages the energy intensive industries which cause more coal consumption and emissions. Therefore the cap of regional coal consumption is necessary to guide the local government, especially those in heavily polluted areas such as Beijing/ Tianjin/Hebei, the Yangtze River Delta and the Pearl River Delta, toward a more sustainable development approach. Coal dressing and washing are important as well. Generally speaking, most raw coal in China is of low quality. The sulfur content of one-third raw coal is over 1%. The average ash content of coal for power generation is at 28%, much higher than the level in the U.S. (8%). Low coal quality leads to extra burden of SO2 and PM emissions abatement from the flue gas. Fortunately, coal dressing and washing could separate sulfur and ash from the coal, hence lower SO2 emissions at approximately 10% cost of FGD approach. Out of 2.3 BMT steam coal consumed in 2010, only one-third was dressed and washed. By increasing the percentage of dressed and washed coal to 70%, which is the average level of developed countries, the SO2 and PM emissions due to coal consumption are expected to be substantially reduced. Furthermore, shutting down small industrial boilers is also essential. Past U.S. experience shows that reduction of SO2 emissions from industrial boilers is mainly attributed to less coal consumption. For example, the U.S. reduced its coal consumption in industrial sector from 169 MMT in 1970 to 63 MMT in 2010,5 consequently lowered the SO2 emissions by 70%. Meanwhile, combined heat and power (CHP) in the power sector was developed to reinforce the heat demand from industrial plants. Following this experience, lots of small boilers in large Chinese cities such as Beijing are gradually replaced by CHP or large boilers. Overall, higher energy efficiency from larger boilers could reduce industrial coal consumption while it is less costly to install and operate emission control equipments. It will bring both energy and environmental benefits to China if a full-scale shutting down of small boilers is carried out.
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AUTHOR INFORMATION
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[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This work is supported by China’s National Environmental Commonweal Research Project (201209001) and the Energy Foundation (R-1011-13568).
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REFERENCES
(1) Lei, Y.; Zhang, Q; He, K; Streets, D. G. Primary anthropogenic aerosol emission trends for China, 1990−2005. Atmos. Chem. Phys. 2011, 11, 931−954. 4264
dx.doi.org/10.1021/es301226n | Environ. Sci. Technol. 2012, 46, 4263−4264
