中国燃煤电厂大气污染物排放研究进展

Research progress of air pollutant emissions of Chinese coal-fired power plants

中国是世界上最大的煤炭生产国和消费国,燃煤电厂是大气污染物主要排放源之一。为持续改善环境空气质量,中国制定和实施了逐步严格的排放标准和控制措施以减少燃煤电厂的大气污染物排放。准确量化燃煤电厂的排放特征和长期趋势对于深入认识煤电行业环境影响至关重要。回顾了20 a来我国燃煤电厂的控制历程与排放标准,对燃煤电厂大气污染物排放的研究进展进行综述,旨在提升对我国煤电行业大气污染控制进程和排放演变规律的认识,并为其环境污染治理提供科学依据。2000—2020年,我国燃煤电厂经历了排放增加、污染缓和、政策加严和超低排放改造4个阶段基于逐步完善的“自下而上”排放清单研究方法,三大常规污染物(PM_(2.5)、SO_(2)和NO_(x))的排放量分别在2004—2005、2005—2006和2011年前后出现拐点并稳步下降。其中,细颗粒物年排放量由百万吨级下降至十万吨级,SO_(2)和NOx年排放量由千万吨级下降至百万吨级。由于对污染治理信息掌握不足,部分全球及亚洲排放清单对我国煤电行业排放水平存在高估。在西电东送等国家战略影响下,我国东部高电力需求区域煤电行业排放占比逐渐下降,而西部能源富集区域排放占比逐渐增加。此外,基于卫星观测的“自上而下”方法也被应用于评估煤电行业排放控制措施的实施效果。过去20 a间,我国煤电装机容量和发电量占比显著下降,但与欧美等发达国家相比仍相对较高。未来应在提高非化石能源利用占比的同时,进一步加强煤炭清洁利用,充分发挥其在电力安全和供应保障中的基础性作用,并持续降低大气污染物和温室气体排放强度,实现减污降碳、协同增效的目标。

China is the largest coal producer and consumer in the world, and the coal-fired power sector is one of the major sources of air pollutants. In order to improve ambient air quality continuously, China has issued and implemented some staged-stringent emission standards and control measures to reduce air pollutant emissions from the sector. Accurate quantification of emission characteristics and long-term trend of coal-fired power plants is essential for deeply understanding the environmental effect of the coal-fired power sector. This paper reviews the control stages, standards and the research progress of coal-fired power sector emissions over the past two decades. It aims to improve the knowledge on air pollution control process and evolution of emissions for the coal-fired power sector and to provide a scientific basis for environmental pollution prevention in the sector. The coal-fired power sector in China has experienced four stages, namely emission growth, emission restraining, policy tightening, and ultra-low emission retrofit for 2000—2020. Based on the gradually improved “bottom-up” methodology, the emissions of three typical pollutants, PM_(2.5),SO_(2)and NO_(x),were estimated to reach the peak around 2004—2005,2005—2006,and 2011,respectively, followed by continuous declines. The annual emissions of PM_(2.5)decreased from million tonnes to hundred thousand tonnes, and those of SO_(2)and NOxfrom ten million tonnes to million tonnes. Attributed to insufficient information on the emission control measures, some global and Asian emission inventories overestimated the level of China coal-fired power sector’s emissions. Influenced partly by the West-to-East Power Transmission Project, the fraction of power sector emissions declined in the eastern provinces with a large demand of electricity, and increased in the western provinces with a large abundance of energy. Besides, the “top-down” method based on satellite observation has been also applied to evaluate the effectiveness of emission control for the coal-fired power sector. For the past two decades, the shares of installed capacity and electricity generation for the coal-fired power have dropped clearly, but they are still at a relatively high level compared to that in European and North American countries. Along with the increase of non-fossil energy in the future, the clean use of coal should be further strengthened to continuously play a basic role in power security and supply and to achieve the target of synergetic control of pollution and carbon emissions.