Quantifying CO2 emissions from a thermal power plant based on CO2 column measurements by portable Fourier transform spectrometers

Carbon dioxide (CO2) emitted from thermal power plants accounts for approximately 40% of energy-related CO2 emissions in the world. CO2 emission datasets for thermal power plants have large uncertainties, especially those from developing countries. We performed CO2 column measurements with solar-viewing portable Fourier transform spectrometers and wind measurements with a Doppler lidar at sites approximately 3–7 km from a thermal power plant in Japan during field campaigns in October 2018 and October/November 2019 to evaluate the uncertainty in CO2 emission estimates based on ground-based atmospheric measurements. Under the assumption that the CO2 plume from a thermal power plant disperses according to a Gaussian plume model, CO2 emission rates were estimated simultaneously with the dispersion coefficient of lateral plume width and wind direction by an optimal estimation method. The estimated CO2 emission rates were in good agreement with those determined from hourly fuel consumption data, with a mean bias of 2.8% and a standard deviation of 16.8%. Analyses of 27 plumes observed for approximately one month during the 2019 campaign when the actual CO2 emission rate was nearly constant revealed that monthly CO2 emissions can be quantified with a precision (standard error) of 6.9% at the 95% confidence level. Evaluations using different wind data demonstrated that accurate data for determining the wind field are of importance in the column measurement-based emission estimates. •CO2 column measurements were performed with portable FTSs around a power plant.•Wind data in the planetary boundary layer were observed with a Doppler lidar.•CO2 emission rates were estimated by two (simple and optimal estimation) methods.•The emission rate uncertainty was evaluated by comparing with fuel consumption.•Precision of monthly emission estimate was equivalent to inventory uncertainties.