Table 415

Estimated Emissions for Nine Priority HAPs from Characteristic Utility Units (1994; short tons per year)0

Fuel Coal

Unit size (MWe): 325

Arsenic 0.0050

Cadmium 0.0023

Chromium 0.11

Lead 0.021

Mercury 0.05

Hydrogen chloride 190

Hydrogen fluoride 14

Dioxinsb 0.00000013

Nickelc NC

aThere are uncertainties in these numbers. Based on an uncertainty analysis, the EPA predicts that the emission estimates are generally within a factor of roughly three of actual emissions.

^These emission estimates were calculated using the toxic equivalency (TEQ) approach, which is based on the summation of the emissions of each congener after adjusting for toxicity relative to 2,3,7,8-tetrachlorodibenzo-p-dioxin (i.e., 2,3,7,8-TCDD). cNot calculated.

which lists nationwide utility emissions estimates for 13 priority HAPs [37]. Table 4-15 contains estimated emissions for 9 priority HAPs from characteristic utility units. In summary, the Utility Hazardous Air Pollutant Report to Congress analyzed 66 other air pollutants (other than mercury, which is discussed in the next section) from 684 power plants that are 25 MW or larger and burning coal, oil, or natural gas [37]. The report noted potential health concerns about utility emissions of dioxin, arsenic, hydrogen chloride, hydrogen fluoride, and nickel, although uncertainties exist about the health data and emissions for these pollutants.


The best estimate of annual anthropogenic U.S. emissions of mercury from 1994 to 1995 is 158 short tons [36]. Approximately 87% of these emissions were from combustion sources, including waste and fossil fuel combustion, as illustrated in Figure 4-20 [63]. Contemporary anthropogenic emissions are only one part of the mercury cycle. Releases from human activities today are adding to the mercury reservoirs that already exist in land, water, and air, both naturally and as a result of previous human activities. One estimate of the total annual global input to the atmosphere from all sources, including natural, anthropogenic, and oceanic emissions, is 5500 short tons [36].

Coal-Fired Utility Boilers

Municipal Waste Combustors

Manufacturing Point Sources (chlor-alkali, cement, and pulp plants) Area Sources (dentistry, paints, and labs)

Commercial/Industrial Boilers

Other Combustion Sources

Medical Incinerators


Commercial/Industrial Boilers

Other Combustion Sources

Medical Incinerators


0 0

Post a comment