With the passage of the 1990 Clean Air Act Amendments (CAAA), accurate determination of the concentration of mercury in coal has become an increasingly important issue. To address this issue, CONSOL R&D conducted a round robin analytical program to determine the interlaboratory and intralaboratory variability in the measurement of mercury in coal. CONSOL supplied homogeneous splits of Pittsburgh and Illinois #6 seam coals, and the NIST 1632b coal standard to eleven laboratories, twice each, over a one-year period. A twelfth laboratory analyzed the coals once. A European coal standard, certified for mercury, was analyzed at the completion of the round robin study to evaluate accuracy. The round robin participants included representatives from industry, government, and academia. The laboratories, which are experienced in mercury-in-coal analysis, used various state-of-the-art sample preparation and analysis procedures in the study. The round robin results indicate that a substantial level of variability exists in the mercury-in-coal determination. Earlier studies1 found similar results. The relative intralaboratory repeatability was 0.02 ppm and the relative interlaboratory reproducibility ranged from 0.04 to 0.05 ppm. The study showed that laboratory variability can be greatly skewed by outlier values. Fifty-six percent of the results for the European coal standard fell within a 95% confidence interval of the standard (0.138 ± 0.11 ppm). These results indicate that accuracy is not method-dependent.

Interlaboratory and intralaboratory variability in the analysis of mercury in coal

Any assessment of control strategies or impacts of potentially hazardous airborne pollutants must begin with the characterization of source emissions. This paper describes a new computer–based model developed for the Electric Power Research Institute (EPRI) to quantify the emissions of chemical species in all gaseous, liquid and solid streams entering and leaving a plant. User–specified parameters allow the model to be tailored to a variety of power plant configurations and site–specific conditions. A unique feature of the model is that all parameters and input data may be characterized probabilistically so that uncertainties can be analyzed rigorously.

A Probabilistic Emissions Model for Managing Hazardous Air Pollutants

Economic evaluation of burning bituminous and western PRB coals for power production based on select pollution control scenarios

The U.S. Environmental Protection Agency (EPA) has been regulating air toxics (hazardous air pollutants) under Section 112 of the 1970 Clean Air Act Amendments. To date, EPA has established emission standards for seven hazardous air pollutants. They include arsenic, asbestos, benzene, beryllium, mercury, vinyl chloride and radionuclides. EPA had determined that the low risks associated with electric utility fossil fuel power plant radionuclide emissions did not justify regulation under Section 112. The Clean Air Act Amendments of 1990 greatly expand EPA's rulemaking authority over toxic or hazardous air pollutants. The law lists 189 chemicals that would be subject to control. Sources that emit 10 tons/yr or more of any one pollutant, or 25 tons/yr or more of any combination thereof, must apply maximum available control technology (MACT). By definition, MACT is at least as stringent as best available control technology (BACT) for similar sources. However, consideration of the cost and feasibility of control, energy impacts and environmental factors will be given in MACT. Under the new amendments, the EPA will conduct a three-year study of the public health hazards from exposure to toxic emissions from utilities and report to Congress. EPA can regulate such emissions only if the regulations aremore » appropriate based on this study. Two additional studies addressing mercury are also required. The first directs the EPA to conduct a four-year study of mercury emissions from electric utility steam generating units, municipal waste combustion units, and other sources. Included in this paper are evaluations of the rate and mass of such emissions, of health and environmental effects, and of the available control technologies and their costs.« less

Greg Behrens

Papers

Managing air toxics under the new Clean Air Act Amendments