Satellite data-driven estimates of NO_x and co-emitted CO₂ from coal-fired power plants in China (2021–2024)

Coal-fired power generation dominates China’s electricity mix and accounts for over one third of fossil CO₂ emissions, with substantial air pollutants. We estimate nitrogen oxides (NO_x) and co-emitted CO₂ emissions from more than 1000 coal-fired power plants in China during 2021–2024 using a lightweight top-down framework. The method combines TROPOMI NO₂ observations, ERA5 wind fields, and variable NO_x/NO₂ ratios from Goddard earth observing system composition forecast within an improved directional derivative approach to derive gridded anthropogenic NO_x flux. Plant-level NO_x emissions are obtained by integrating weighted contributions from multiple plants within a 15 km radius at monthly temporal resolution, facility-specific CO₂/NO_x emission ratios are applied to infer CO₂. Estimated annual NO_x emissions decrease from 5.49 to 4.78 Mt during 2021–2024, while CO₂ emissions decrease from 4.61 to 4.10 Gt. Corresponding uncertainties are 30.9%–31.5% for NO_x and 31.3%–32.0% for CO₂. A confidence assessment based on internal statistical consistency and external physical plausibility constraints classifies 85.1% of plant-level estimates as high and medium confidence, showing good agreement between observational indicators and derived emissions and supporting the robustness of the framework. The approach performs less reliably for low-capacity facilities and for regions with sparse satellite coverage or relatively high wind speeds.