重污染天气下电力行业排放对京津冀地区PM2.5的贡献

利用CAMx(区域空气质量模型)中的PSAT(颗粒物源示踪技术),分析了重污染天气下分区域、分行业的污染物排放对京津冀地区PM_2.5的贡献,设计了分行业排放的环境影响效率系数(EESCR)计算方法,并对“电能替代”(以电力行业产能替代民用能源消耗)情景方案下的排放进行模拟分析. 结果表明:在重污染天气背景下,电力行业排放对京津冀地区ρ(PM_2.5)的贡献率较低,各地均低于10%,并且区域排放的贡献次序为京津冀以外地区>京津冀其他城市>当地,这与电力行业高架源排放的特征有关,而工业和民用行业对区域排放的贡献次序相反. PM_2.5主要组分和前体物的分行业EESCR计算结果表明,电力行业ESSCR值均在y=1/2x趋势线之下,远低于其他行业,因此优先控制其他行业排放才是改善京津冀地区空气质量的关键.电能替代的情景模拟结果表明,电能替代是有效降低京津冀地区ρ(PM_2.5)的可行方式. 研究显示,充分利用电力行业高架源排放的特点和便于集中处理的行业优势,尽力降低因产能增长带来的排放增量,实施电能替代可成为改善区域空气质量的有效途径之一. 

Contribution of Power Plant Emissions to PM2.5 over Beijing-Tianjin-Hebei Area during Heavy Pollution Periods

Abstract: PM_2.5 contributions from different emission sources and source regions over the Beijing-Tianjin-Hebei area were analyzed by implementing a simulation of the Comprehensive Air Quality with extensions (CAMx) model equipped with Particulate Source Apportionment Technology (PSAT) technique during a period when heavy pollution happened frequently. By utilizing the PSAT results, a method to calculate the efficiency of environmental impacts (EESCR) using source contribution ratio for each emission sector was designed. A scenario analysis using power plant energy to replace domestic consumption (electric power alternative) was conducted in the present study. The results showed that emissions from the power plant sector made a rather low contribution (less than 10%) to PM_2.5 during the heavy polluted periods over the Beijing-Tianjin-Hebei area. The contribution of the power plant sector from regions other than the Beijing-Tianjin-Hebei area was greater than that from other cities over the Beijing-Tianjin-Hebei, which was greater than that from local sources. This was attributed to the power plant sector being an elevated source. Meanwhile, the sequence of contributions from both industrial and domestic sectors corresponding to regions showed the opposite trend. EESCR calculated for PM_2.5 components and the major precursors showed that the EESCR value of the power plant sector was less than y=1/2x, and much lower than the other sectors. Thus, emission mitigation of sources other than power plants should be the key to improving air quality over the Beijing-Tianjin-Hebei area. The scenario analysis of electric power alternatives showed that it is a feasible way to reduce PM_2.5 over the Beijing-Tianjin-Hebei area. Therefore, by taking full advantage of high stack emissions and the efficiency of centralized disposal in the power plant sector, while alleviating the emission increment caused by the growth of energy capacity, electric power alternatives should become one of the effective ways to improve the regional air quality.