煤电大气汞驱动因素、排放预测和减排策略研究:以辽宁省为例

煤电是我国汞污染的重要来源,旨在控制汞排放的《水俣公约》也将煤电列为重点管控源.因此,我国急需提出科学合理的策略以指导煤电汞减排工作.明确煤电汞排放的驱动因素以及预测未来趋势是制定污染控制政策的基础.鉴于此,本文以辽宁省为例,综合运用对数平均迪氏分解法、环境学习曲线和情景分析模型,辨识了燃煤电厂汞排放的主要影响因素,并预测了未来十年的大气汞排放量.结果显示:2006—2017年排放从5009kg(-57.8%,79.1%)大幅下降至1419kg(-61.1%,80.2%),排放因子、煤炭消耗效率和电力行业结构是汞排放的主要抑制因素,而电力需求拉动了辽宁省大气汞排放.在基准情景下,燃煤电厂大气汞排放从2017年的1419kg下降至2030年的1243kg.在环境规划和严格控制情景下,2030年燃煤电厂大气汞排放分别下降了1200kg和1274kg.最后,本文针对辽宁省汞减排提出一系列政策建议:①通过优化电厂污染物控制设施,提高洗煤比例等措施降低汞排放因子;②继续淘汰低效燃煤电厂,并推广节能技术以提高煤炭消耗效率;③推进风能、光能等可再生能源替代煤电.

Drivers, Projection and Mitigation Strategies of Atmospheric Mercury Emissions from Coal-fired Power Plants: A Case Study of Liaoning

The coal-fired power plants (CFPPs) are one of the crucial contributors to mercury pollution in China. The Minamata Convention, aiming at mercury mitigation in 2013, has listed CFPPs as key regulatory targets. Thus, China urgently needs the scientific and reasonable strategies to guide the mercury reduction from CFPPs. Identifying the driving factors and projecting future mercury emissions are fundamental for mercury control policy design. Given that, this study selects Liaoning Province as the case to evaluate the key determinants of historical atmospheric mercury emissions from CFPPs and draw the emission evolution trajectory from 2020 to 2030, by using the logarithmic mean divisia index (LMDI) and the learning curve combined with scenario analysis, respectively. The results show that during 2006-2017, atmospheric mercury emissions of CFPPs in Liaoning continuously decreased from 5008 kg (-57.8%,79.1%) to 1419 kg (-61.1%,80.2%). The emission factor, coal use efficiency, and power industrial structure are main inhibitory factors of Liaoning''s mercury emissions, while the power demand plays the major role in the growth of mercury emissions. Additionally, under business as usual (BAU), average atmospheric mercury emission of CFPPs in Liaoning Province will change from 1419 kg in 2017 to 1243 kg in 2030. Under the environmental planning scenario (EPS) and strictly controlled scenario (SCS), atmospheric mercury emissions of CFPPs will drastically reduce by 1200 kg and 1274 kg in 2030 based on the 2017 level. Finally, this study provides insights for mercury mitigation policies of Liaoning Province. Measures such as updating air pollution control devices of CFPPs and increasing the rate of coal washing to decrease the mercury emission factor are recommended. Decommissioning the inefficient CFPPs and promoting energy-saving technologies should be enhanced to increase the coal use efficiency. Last but not least, the government should accelerate the development of the renewable energy, such as wind and solor energy, to replace the CFPPs.