Spatio-temporal heterogeneity and synergistic effects of air pollutants and CO2 emissions from Chinese coal-fired industrial boilers

Coal-fired industrial boilers (CFIBs) are critical in reducing air pollution and CO2 emissions. Based on the built-up emission inventories of particulate matter (PM and PM2.5), SO2, NOx, mercury (Hg), and CO2 from CFIBs in China from 1991 to 2020, this study explored their spatiotemporal heterogeneity and synergistic effects. Results showed that huge winter heating demand and long-term coal-dominated energy structure caused the northeast region to have the largest air pollutants and CO2 emissions, accounting for 25.3 %-40.8 % of the national emissions. The high correlation between air pollutants and CO2 emissions by province (R2 = 0.542-0.942) demonstrates the homogeneity of the dominant sources. NOx exhibited the greatest potential for synergistic CO2 reduction, with provincial NOx/CO2 values ranging from 650 to 1532.4 g/t, which were higher than those of PM/CO2 and SO2/CO2. From 1991 to 2020, air pollutants and CO2 emissions showed growth trend, followed by a rapid decline. Additionally, significant co-control of CO2 emissions was achieved through policies targeted at reducing PM, SO2, and Hg emissions. CO2 emissions peaked in 2012 and then declined annually at an average annual rate of 11.1 %. The driving factors showed varying magnitudes of influence on air pollutants and CO2 emissions.