SO_2 mitigation in China's coal-fired power plants: A satellite-based assessment on compliance and enforcement

摘要

Compliance monitoring plays an indispensable role in enforcing environmental policies for achieving compliance. This study examines the compliance and enforcement of SO2 mitigation policies in China's coal-fired power plants from both temporal and spatial perspectives with Aura Ozone Monitoring Instrument (OMI) level 2 sulfur dioxide total column product (OMSO2 v003). We apply a pixel-averaging method with the pixel size being 0.02 x 0.02 degrees, the time range being one year, and the averaging radius being 18 km. Results show that SO2 Vertical Column Density (VCD) enhancements of coal-fired power plants decreased by 94.3% from January 2006 to April 2020. Most of the reduction took place in two compliance episodes, being in 2008 and after 2014. They can be related to the "desulfurized electricity tariff" and the "ultra-low emission" policies that entered into effect in July 2007 and from September 2013, respectively. Furthermore, the SO2 VCD enhancements rebounded in 2006 and 2011, the first years of 11th and 12th Five-Year Plans to reflect likely more relaxed enforcement and compliance. Policy enforcement differed significantly across provinces as indicated by when their coal-fired power plants complied and how much reduction was made. Environmental supervision and inspection could target those provinces with poorer compliance statuses for more effective and efficient enforcement.