Growth in NOx emissions from power plants in China: bottom-up estimates and satellite observations

Other literature type English OPEN
Wang, S. W. ; Zhang, Q. ; Streets, D. G. ; He, K. B. ; Martin, R. V. ; Lamsal, L. N. ; Chen, D. ; Lei, Y. ; Lu, Z. (2012)

Using OMI (Ozone Monitoring Instrument) tropospheric NO<sub>2</sub> columns and a nested-grid 3-D global chemical transport model (GEOS-Chem), we investigated the growth in NO<sub>x</sub> emissions from coal-fired power plants and their contributions to the growth in NO<sub>2</sub> columns in 2005–2007 in China. We first developed a unit-based power plant NO<sub>x</sub> emission inventory for 2005–2007 to support this investigation. The total capacities of coal-fired power generation have increased by 48.8% in 2005–2007, with 92.2% of the total capacity additions coming from generator units with size &ge;300 MW. The annual NO<sub>x</sub> emissions from coal-fired power plants were estimated to be 8.11 Tg NO<sub>2</sub> for 2005 and 9.58 Tg NO<sub>2</sub> for 2007, respectively. The modeled summer average tropospheric NO<sub>2</sub> columns were highly correlated (<i>R</i><sup>2</sup> = 0.79–0.82) with OMI measurements over grids dominated by power plant emissions, with only 7–14% low bias, lending support to the high accuracy of the unit-based power plant NO<sub>x</sub> emission inventory. The ratios of OMI-derived annual and summer average tropospheric NO<sub>2</sub> columns between 2007 and 2005 indicated that most of the grids with significant NO<sub>2</sub> increases were related to power plant construction activities. OMI had the capability to trace the changes of NO<sub>x</sub> emissions from individual large power plants in cases where there is less interference from other NO<sub>x</sub> sources. Scenario runs from GEOS-Chem model suggested that the new power plants contributed 18.5% and 10% to the annual average NO<sub>2</sub> columns in 2007 in Inner Mongolia and North China, respectively. The massive new power plant NO<sub>x</sub> emissions significantly changed the local NO<sub>2</sub> profiles, especially in less polluted areas. A sensitivity study found that changes of NO<sub>2</sub> shape factors due to including new power plant emissions increased the summer average OMI tropospheric NO<sub>2</sub> columns by 3.8–17.2% for six selected locations, indicating that the updated emission information could help to improve the satellite retrievals.
Share - Bookmark