Satellites Underestimate Power Plant CO₂ Emissions by 70%, Study Finds

Current satellite systems underestimate total CO₂ emissions from U.S. thermal power plants by 70% (±12%), according to a study published in the Journal of Remote Sensing. Led by researchers at the Aerospace Information Research Institute (AIR) under the Chinese Academy of Sciences (CAS), the analysis highlights critical gaps in remote sensing technology, including coarse spatial resolution (1.29×2.25 km² for the Orbiting Carbon Observatory-2 satellite, or OCO-2; 1.6×2.2 km² for OCO-3), limited precision (~1 ppm), and infrequent revisit cycles (16 days). However, the study estimates that next-generation satellites—equipped with 0.5 km resolution, a precision of at least 0.7 ppm, and daily monitoring capabilities—could reduce errors to below 20%. This advancement would represent a transformative leap in strengthening global carbon accountability.

Thermal power generation drove 46% of the global increase in CO₂ emissions in 2021, underscoring its role as a linchpin for climate action. While ground-based systems like the U.S. Environmental Protection Agency's Clean Air Markets Program Data (CAMPD) provide precise hourly emissions data, they lack global scalability. Satellites such as NASA's OCO-2 and OCO-3 struggle to detect smaller facilities, which constitute 94% of coal-fired units (under 900 MW) and 97% of gas-fueled plants (under 600 MW). The study analyzed 1,060 U.S. power plants using 2021 satellite data and found current systems captured only 29% (±12%) of total emissions, primarily from large facilities.

Through computational modeling, researchers demonstrated that improving satellite precision to 0.5 ppm would boost detection to 48% of total emissions. Combining 0.5 km spatial resolution, 0.7 ppm precision, and daily overpasses could slash aggregate errors to under 20%. The team integrated Gaussian plume models and high-resolution ERA5-Land meteorological data to correct for temporal variability in plant operations and atmospheric interference, refining emission estimates.

The study also evaluated upcoming missions like the European Union's Copernicus Anthropogenic CO₂ Monitoring Mission (CO2M)—set for 2025 with 0.7 ppm precision, 4 km² resolution, and 5-day revisits—and China’s TanSat-2, designed for 1 ppm precision and daily global coverage. These systems could detect 52% and 44% of total U.S. power plant emissions, respectively, a significant improvement over current capabilities. 

Accurate emission inventories are critical for the Paris Agreement's Global Stocktake, which evaluates progress toward limiting warming to 1.5°C. "Current satellites provide incomplete data, undermining climate commitments," said Dr. CHENG Tianhai, the study's corresponding author. "Next-generation systems could resolve these gaps, ensuring emissions are measurable and actionable." With upgraded satellites launching by 2025, the global community may soon close loopholes in carbon governance, enhancing transparency and accelerating the shift to low-carbon energy systems.

The image abstract. (Image by AIR)