Quantification of Variability and Uncertainty in Air Pollutant Emission Inventories: Method and Case Study for Utility NOx Emissions

• Published in: Journal of the Air & Waste Management Association (1995) Vol. 52; no. 9; pp. 1083 - 1095
• Main Authors: Frey, H. Christopher, Zheng, Junyu
• Format: Journal Article
• Language: English
• Published: Pittsburgh, PA Taylor & Francis Group 01.09.2002; Air & Waste Management Association
• Subjects: Air Pollutants - analysis; Air pollution caused by fuel industries; Applied sciences; Atmospheric pollution; Combustion and energy production; Cost Savings; Energy; Energy. Thermal use of fuels; Environment; Environmental Monitoring - economics; Environmental Monitoring - standards; Exact sciences and technology; Metering. Control; Nitrogen Oxides - analysis; Policy Making; Pollution; Pollution sources. Measurement results; Reproducibility of Results; Sensitivity and Specificity; Vehicle Emissions - analysis; Data analysis; Emission content; Coal power plant; Pollution source inventory; Air pollution; Air quality; Pollutant emission; Nitrogen Oxides
• ISSN: 1096-2247; 2162-2906
• DOI: 10.1080/10473289.2002.10470837

The quality of stationary source emission factors is typically described using data quality ratings, which provide no quantification of the precision of the emission factor for an average source, nor of the variability from one source to another within a category. Variability refers to actual differences caused by differences in feedstock composition, design, maintenance, and operation. Uncertainty refers to lack of knowledge regarding the true emissions. A general methodology for the quantification of variability and uncertainty in emission factors, activity factors, and emission inventories (EIs) is described, featuring the use of bootstrap simulation and related techniques. The methodology is demonstrated via a case study for a selected example of NO x emissions from coal-fired power plants. A prototype software tool was developed to implement the methodology. The range of interunit variability in selected activity and emission factors was shown to be as much as a factor of 4, and the range of uncertainty in mean emissions is shown to depend on the interunit variability and sample size. The uncertainty in the total inventory of −16 to +19% was attributed primarily to one technology group, suggesting priorities for collecting data and improving the inventory. The implications for decision-making are discussed.