The Total Emission Estimation of Thermal Power Plants Using a Top-Down Approach Strongly Impacted by Satellite Spatial Resolution, Precision, and Monitoring Frequency

Accurately estimating carbon emissions is crucial under the Paris Agreement, especially for thermal power plants, the largest source of fossil fuel emissions. While traditional methods are validated by satellite remote sensing, the effectiveness of satellites like the Orbiting Carbon Observatory (OCO) for national-level carbon inventories remains debated. This study evaluates satellite capabilities in monitoring emissions from thermal power plants, considering frequency, column-averaged dry-air mole fraction of CO2 (XCO2) precision, and spatial resolution. A correction strategy is proposed for global carbon stocktake using satellite data. The study reveals that the OCO-2 v11.1 and OCO-3 v10 satellites, with their approximate 1 part per million (ppm) XCO2 precision, substantially underestimate total U.S. power plant emissions by 70% (+/- 12%) due to their inability to detect emissions from smaller facilities. Improving precision to 0.5 ppm can narrow this gap to 52% (+/- 17%). Further reductions in this discrepancy can be achieved by enhancing monitoring frequency, XCO2 precision, and spatial resolution. Specifically, with a precision of 0.7 ppm, a spatial resolution of 0.5 km, and daily monitoring, the error can be decreased to less than 20%. A parallel analysis of the planned Copernicus Anthropogenic CO2 Monitoring Mission estimates that it could detect 52% of total U.S. power plant emissions, while TanSat-2 Global is projected to detect 44%. The findings highlight current limitations in satellite-based global carbon stocktake but indicate future potential improvements with higher spatiotemporal resolution and precision in upcoming satellite missions.