Emissions of NOx, SO2 and CO2 From Power Plants: Evaluating Continuous Emissions Monitoring Systems (CEMS) Data Using Airborne Field Measurements.

Airborne studies of power plant emissions were conducted during the Southern Oxidants Study (SOS) in 1999, the Texas Air Quality Study (TexAQS) in 2000 and the Intercontinental Transport and Chemical Transformation (ITCT) study in 2002. Measurements of NO_y, CO₂ and SO₂ were made in near-field transects of power plant plumes aboard the NOAA WP-3D and NCAR L-188 Electra aircraft. Ratios of the primary emissions NO_y, SO₂ and CO₂, and/or fluxes of those gases determined by integration of plume mixing ratios, were compared to data from CEMS equipment installed to directly measure plant emissions from power generation units. This study presents field measurements from over 180 transects of plumes from 20 separate power plants in the Eastern and Western United States and Texas. Estimates of accuracy for the CEMS equipment are presented and probable impacts to annual point source emissions inventories are discussed.