w
United States Office of Air Quality EPA-450/3-78-110c
Environmental Protection Planning and Standards September 1978
Agency Research Triangle Park NC 27711
Air
&EPA The Development of
Mathematical Models for
the Prediction of
Anthropogenic Visibility
Impairment
Volume
Case Studies for
Selected Scenarios
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EPA-450/3/78-llOc
Volume III: Case Studies for Selected Scenarios
THE DEVELOPMENT OF MATHEMATICAL MODELS
FOR THE PREDICTION OF ANTHROPOGENIC
VISIBILITY IMPAIRMENT
by
Douglas A. Latimer
Systems Applications, Incorporated
San Rafael, California 94903
Contract 68-02-2593
EPA Project Officer: Russell F. Lee
Prepared for
U. S. ENVIRONMENTAL PROTECTION AGENCY
Office of Air, Noise, and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
September 1978
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11
DISCLAIMER
This report has been reviewed by the Office of Air Quality Planning
and Standards, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products consti-
tute endorsement or recommendation for use.
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111
CONTENTS
Disclaimer ii
List of Illustrations iv
List of Tables iv
Key to Parametric Studies of Emissions Rates v
Key to Parametric Studies of Plume-Observer Distances, Sulfate
Formation Rates, and Background Ozone Concentrations v
I Introduction 1
II Assumed Input Emission and Ambient Conditions 4
III Interpretation of Visibility Impairment Parameters .... 8
A. Percent Reduction in Visual Range 8
B. Blue-Red Ratio 9
C. Plume Contrast 9
D. Plume Perceptibility Parameter AE 10
E. Summary 11
IV Effects of Emissions, Atmospheric Stability, and
Scattering Angle on Plume Visibility Impairment 13
V Effects of Plume Observer Distance, Background Visual
Range, and Atmospheric Stability on Plume Visibility
Impairment 26
VI Effect of S02-to-Sulfate Conversion Rate or
Visibility Impairment 45
VII Effect of N02 Formation Rate Due to Different Background
Ozone Concentrations on Visibility Impairment 62
VIII A Summary of Typical Visibility Impairment Caused by Power
Plants in the Eastern and Western United States ...... 79
IX Summary and Conclusions ...... gg
REFERENCES . 90
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IV
ILLUSTRATIONS
1 Geometry of Plume, Observer, and Sun Assumed in Calculations . . 7
2 Key to Parameters Used To Characterize Visibility Impairment . . 12
3 Calculated Plume Visibility Impairment 17
4 Effect of Plume-Observer Distance on Calculated
Visibility Impairment 29
5 Effect of Sulfate Formation on Calculated Plume
Visibility Impairment 46
6 Effect of Background Ozone on Calculated Plume
Visibility Impairment 63
7 Comparison of Plume Visibility in the Eastern and
Western United States 80
TABLE
1 Input Parameters Used in Calculations 5
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KEY TO PARAMETRIC STUDIES OF EMISSION RATES
Scattering
Angle
45°
90°
180°
Pasquill
Stability
Category
3(a)
3(b)
3(0
3(d)
3(e)
3(f)
3(g)
3(h)
3(1)
17
18
19
20
21
22
23
24
25
Note: Base conditions are 2250 Mwe power plant,
130 km background visual range (average for
western United States), 2.5 km plume-
observer distance, and 0.04 ppm background
ozone concentration. Each figure presents
results for four emission rates.
KEY TO PARAMETRIC STUDIES OF PLUME-OBSERVER DISTANCES,
SULFATE FORMATION RATES, AND BACKGROUND OZONE CONCENTRATIONS
Parameter Varied
Case
Region
Eastern
United
States
Western
United
States
Background
Visual
Range
(km)
15
•(average)
30
(best)
130
(average)
200
(best)
Power
Plant
Size
(Mwe)
2250
750
2250
750
2250
750
2250
750
Pasquill
Stability
Category
D
E
D
D
D
E
D
E
D
E
0
E
D
E
D
E
Plume-Observer
Distance (2.5,
5, and 10 km)
Figure
4(a)
4(b)
4(c)
4(d)
4(e)
4(f)
4(g)
4(h)
4(i)
4(j)
4(k)
4(1)
4(m)
4(n)
4{o)
4(p)
Page
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
Sulfate
Formation
Rate (0, 0.5,
and 5%/hr)
Figure
5(a)
5(b)
5(c)
5(d)
5(e)
B(f)
5(g)
5(h)
5(1)
5(j)
5(k)
5(1)
5(m)
5(n)
5(0)
5(p)
Page
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
Background
Ozone Concentra-
tion (0, 0.04,
and 0.1 ppm)
Figure
6(a)
6(b)
6(c)
6(d)
6(e)
6(f)
6(9)
6(h)
6(1)
6(j)
6(k)
6(1)
6(m)
6(n)
6(0)
6(p)
Page
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
East-West
Comparison
Figure
7(a)
7(b)
7(c)
7(d)
7(e)
7(f)
7(9)
7(h)
7(a)
7(b)
7(c)
7(d)
7(e)
7(f)
7(g)
7(h)
Page
80
81
82
83
84
85
86
87
80
81
82
83
84
85
86
87
Note: Except as indicated otherwise on figures, the base case conditions are 5.0 km plume-observer
distance, 0.5 percent/hr sulfate formation rate, 0.04 ppm background ozone concentration,
and 90" scattering angle.
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I INTRODUCTION
This report presents calculations of visibility impairment caused
by hypothetical coal-fired power plants under different assumed emission,
meteorological, and ambient background conditions. Calculations were per-
formed using the Gaussian-based plume visibility model developed by Systems
Applications, Incorporated (SAI) for the U.S. Environmental Protection
Agency and described in Volumes I and II of this report. Graphs are used
to illustrate the impact on calculated visibility impairment of various
typical values of the following input parameters (see keys on page v):
> Emission rates.
> Atmospheric stability.
> Location of the observer relative to the power
plant and the plume centerline.
> Direction of view relative to the sun (scattering
angle).
> Ambient background visual range.
> Ambient background ozone concentration.
> Sulfate formation rate.
In the Clean Air Act Amendments of 1977, Congress defined visibility
impairment to include a reduction in visual range and atmospheric discolor-
ation. Four parameters that quantify visibility impairment caused by plumes
have been selected for the graphs:
> Percent reduction in visual range (from background).
> Blue-red ratio (indicative of the plume coloration relative
to the background, clear horizon sky).
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> Plume contrast (relative to the background sky—indicative
of the relative brightness of the plume).
> Plume perceptibility parameter A£ (proportional to the
plume perceptibility as a result of both brightness
and color differences between the plume and the background
sky).
This document is designed to offer the air quality analyst a
quick reference for estimating visibility impairment caused by modern,
large coal-fired power plants controlled to meet EPA's current New Source
Performance Standards (NSPS) (Federal Register, 1976). These standards
require efficient particulate control devices (e.g., electrostatic precip-
itators, baghouses, or wet scrubbers) for meeting the 20 percent opacity
requirement. Meeting the current SCL emission standard* of 1.2 lbs/10
Btu requires flue gas desulfurization in the case of high-sulfur, Eastern
coal, but no scrubbing for many low-sulfur, Western coals. Meeting the
current 0.7 lbs/10 Btu NO emission standard requires modern boiler com-
A
bustion design.
This document is limited to a few emission, meteorological, ond ambient
conditions that are considered typical; therefore, it is by no means meant
to replace detailed model calculations or measurement programs that are
carried out to identify visibility impairment. For example, these calcula-
tions would not be appropriate for estimating the impact caused by older
power plants with inefficient particulate control equipment. Also, impacts
during stable, light wind conditions would be much larger than those
presented here, which assume a moderate wind speed of 5 m/s (11 mph).
Furthermore, the impact caused by secondary aerosol—sulfates and nitrates--
could be larger than those indicated here if catalytic particulates (e.g.,
iron, manganese) are emitted, if ambient concentrations of reactive species
(e.g., OH«, NH_) are large, or if water droplets (e.g., from clouds, fog,
or cooling tower plumes) are present.
* More restrictive emission standards have recently been proposed.
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The calculations presented here are based on certain assumptions
regarding viewing conditions. It is assumed that the plume is viewed
on a horizontal line of sight perpendicular to the plume centerline. If
the plume were viewed down the centerline (e.g., if the observer were
in an airplane or on elevated terrain), or if it were viewed obliquely,
visibility impairment would be greater. Also, it is assumed that the
viewing background behind the plume is the clear horizon sky. If a
bright, white cloud or dark terrain feature were behind the plume, the
coloration and perceptibility of the plume would change. For example,
with a bright, white background, wavelength-dependent light scattering
caused by aerosols contributes to the yellow-brown coloration similar to
that caused by NO- light absorption.
Although the vertical diffusion of the plume is eventually limited
to the mixed layer between the ground and the capping, stable layer, it is
assumed that Pasquill-Gifford dispersion coefficients correctly describe
the growth of the power plant plume at intermediate distances. There
is increasing evidence that power plant plumes, due to entrainment during
plume rise, are initially more dilute than are indicated by Pasquill-
Gifford a a 's; and that because of their elevation, plumes diffuse
less rapidly than Pasquill-Gifford a a 's indicate (Carpenter et al., 1971;
Husar et al., 1978; Smith et al., 1978). Since visibility impairment is
strongly dependent on the vertical thickness of the plume for horizontal
lines of sight, it is essential that plume a 's be known as accurately as
possible in order to predict visibility impairment accurately. Also, since
plume a a 's at distances greater than 50 km downwi
the calculations presented here are estimates only.
Finally, the user of this document is cautioned about interpolating
and extrapolating these results for different conditions. NO^ formation
in power plant plumes is diffusion-limited, that is, it is limited by the
rate at which background ozone is entrained into the plume. Consequently
one cannot simply substitute a ratio of these discoloration effects to cor-
respond to light wind cases or to cases involving different emission rates.
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II ASSUMED INPUT EMISSION AND AMBIENT CONDITIONS
Calculations were performed using the plume visibility model for
assumed emissions from hypothetical coal-fired power plants consisting
of one and three 750-Mwe units, assuming EPA's NSPS are just met.
Table 1 summarizes the emission parameters.
Emission rates of fly ash, SOp, and NO were computed from the
NSPS emission limits of 0.1, 1.2, and 0.7 lbs/106 Btu, respectively;
however, fly ash emissions were controlled not by the above mass emission
limit, but by the 20 percent limitation on stack opacity. Emission
parameters were calculated for a subbituminous B coal with a heating
value of 9600 Btu/lb; if a different coal were used, emission parameters
would change somewhat. It was assumed that the emitted fly ash (after
particulate removal) has a mass median diameter of 1 vim, a geometric
3
standard deviation of 2, and a density of 2 g/cm . On the basis of Hie
calculations for this fly ash size distribution, it was found that
99.6 percent efficient particulate control equipment would be required
for this particular coal to meet the NSPS 20 percent stack opacity limit.
Table 1 also shows the meteorological and ambient conditions used in
the calculations. A typical (average) wind speed of 5 m/s (11 mph) at plume
level and two stability categories were used: Pasquill D (neutral) and
Pasquill E (slightly stable). Calculations were carried out to 250 km down-
wind from the source, assuming that uniform meteorological conditions per-
sist that long (14 hours).* For Pasquill D conditions vertical mixing is
eventually limited by the height of the mixed layer: 1500 m (for the eas-
tern United States) and 2000 m (for the western United States). For cases
* Power plant plumes have been tracked and measured as far as 300 km down-
wind (Husar et al., 1978; Smith et al., 1978).
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TABLE 1. INPUT PARAMETERS USED IN CALCULATIONS
Parameter
Coal-fired power plant emission conditions
*Number of boilers and stacks
*Power output
Flue gas temperature
Flue gas flow rate per stack
Fly ash emission rate per 750-Mwe boiler
Stack opacity
Fly ash mass median diameter
Fly ash size distribution geometric
standard deviation
S02 emission rate per 750-Mwe unit
*NOX emission rate per 750-Mwe unit,
as fto2
Meteorological and ambient conditions
Wind speed
*Stability category
*Background visual range
Background Oj concentration
*Assumed pseudo-first-order sulfate
formation rate
Assumed pseudo-first-order nitrate
formation rate
Assumed surface deposition velocities
*Scattering angle
*Plume-observer distance
Value
3, [1]
2250, [750] Mwe
250°F = 121°C
1,724,000 acfm = 814 m3/sec
1.15 tons/day = 12.1 g/sec
20%
1.0 urn
2.0
92.15 tons/day = 968 g/sec
53.75, [0] tons/day = 5.64,
[0] g/sec
5.0 m/sec
Pasquill C, D, and E
[Typical—eastern U.S.: 15 km],
[Best—eastern U.S.: 30 km],
Typical--western U.S.: 130 km,
[Best—western U.S. : 200 km]
[0.0], 0.04, [0.12] ppm
[0], 0.5, [5] %/hr
0 %/hr
1 cm/sec for gases, 0.1 cm/sec
for particles
[45°], 90°, [180°]
[2.5],f 5, [10] km
* Parameters that were varied in the sensitivity analysis.
t A plume-observer distance of 2.5 km was used as base value for Fiaures
2(a) through 2(i).
[ ] = Values of parameters when varied from the base value.
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where vertical mixing is more severely limited, visibility impairment would
be greater. Four background visual ranges were assumed in the calculations;
they are representative of the typical and best eastern United States
conditions (15 and 30 km) and the typical and best western, nonurban U.S.
conditions (130 and 200 km). Background ozone concentrations were varied
from the base case as shown in the table.
Three sulfate formation rates were assumed in the calculations, as
shown. The 0.5 percent per hour rate is considered to be typical of most
nonurban conditions. The 5 percent per hour value is representative of
fast gas-to-particle conversion that could occur in polluted areas. Owing
to the lack of quantitative data on nitrate formation in plumes, a nitrate
formation rate of 0 was assumed; the validity of this assumption is uncer-
tain. Secondary plume sulfate aerosol is assumed to be in the submicron
range, with a mass median diameter of 0.18 urn, based on power plant plume
measurements near St. Louis (Whitby and Sverdrup, 1978). Aerosol in this
size range is most effective per unit mass in scattering light.
Several scattering angles were assumed: For the base case, a scat-
tering angle of 90° and a solar zenith angle of 45° were used for various
observer locations from 1 to 250 km downwind of the power plant and at
several distances (2.5, 5, and 10 km) from the plume centerline. Figure 1
illustrates the orientations of the observer, plume, and sun that were
assumed in calculations. Note that calculated visual impact refers to
specific lines of sight, not to "prevailing visibility."
The effect of surface deposition on the pollutant mass flux at a given
downwind distance was considered in the calculations. The surface deposi-
tion velocity was assumed to be 1 cm/sec for gases (e.g., S0? and NO ) and
£• /\
0.1 cm/sec for particles (e.g., fly ash and SOT).
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Ill INTERPRETATION OF VISIBILITY IMPAIRMENT PARAMETERS
Each of the accompanying figures displays four parameters that charac-
terize visibility impairment:
> Percent reduction in visual range
> Blue-red ratio
> Plume contrast
> AE.
In this section we briefly define these parameters and describe what typical
values for them mean using the following qualitative terms: bright and dark;
yellow, brown, white, and grey discoloration; imperceptible and perceptible.
More detailed explanations of these parameters and details concerning the
models used to calculate them are given in Volume I of this report.
A. PERCENT REDUCTION IN VISUAL RANGE
Visual range is defined as the farthest distance at which a black
object can be perceived against the clear horizon sky. The percent reduc-
tion in visual range is calculated as follows:
x 100%
where r is the visual range for views through the plume center and rvo is
the visual range without the plume (ambient background visual range). In
most situations, the percent reduction in visual range is directly propor-
tional to the integral of the plume light scattering and absorption coef-
ficients along the line of sight and is independent of the background
visual range. The percent reduction in visual range is indicative of the
"haziness" of objects observed through the plume. Until it is diffused,
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the plume will affect only a few of the observer's lines of sight; there-
fore, calculated visual range reduction pertains only to specific lines of
sight through the plume center (perpendicular to the plume center! ine),
not to prevailing visibility. The magnitude of visual range reduction is
not necessarily related to the perceptibility of the plume or to atmo-
spheric discoloration. A significant reduction in visual range could
occur without a perceptible plume or atmospheric discoloration. This
occurrence is illustrated in our subsequent discussion of plume impact
under typical ambient conditions for the eastern United States.
B. BLUE-RED RATIO
The blue-red ratio indicates the coloration of the plume relative to
the unaffected background sky. It is the ratio of the plume light inten-
sity at the blue end of the visible spectrum (A = 0.4 ym) to that at the
red end (x = 0.7 pm) divided by the same ratio for the background:
,
"
A ratio of 1 indicates that the plume is the same color as the background
sky, though not necessarily of the same brightness. Ratios greater than 1
indicate bluish discoloration relative to the background, and ratios of
less than 1 indicate yellowish discoloration. If the background sky is
blue, the plume could be white or grey with a ratio of less than 1 because
the ratio is a relative discoloration index. The plume color will be a
more saturated yellow with decreasing values of this ratio (<0.9).
C. PLUME CONTRAST
Plume contrast is the normalized difference in light intensity of the
plume relative to the background:
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10
I (0.55 um) - Ib(0.55
Cp = Ib(0.55 ym)
Contrast is evaluated at a wavelength A of 0.55 ym, which is the midpoint
of the visible spectrum where the human eye is most sensitive. With no
color shifts (that is, with a blue-red ratio = 1), a plume will be visible
only if it is sufficiently brighter (C > 0) or darker (C < 0) than the
background sky. There are no experimental data concerning the percepti-
bility threshold contrast for plumes. A threshold contrast of 0.02 is
used in defining the perceptibility of a dark object against the horizon
sky in the calculation of visual range; however, it is likely that the
threshold contrast for plumes is greater than 0.02 because, in many cases,
the boundary between a plume and the background is not distinct owing to
the nature of plume dilution. The use of the blue-red ratio in conjunction
with the plume contrast at 0.55 ym is a simple way of characterizing plume
color. When R > 1, the plume is more blue than the background; when R < 1,
the plume is redder (or more yellow-brown); when R = 1, with C (0.55 ym) > 0,
the plume is a brighter white than the horizon, and with C (0.55 urn) < 0,
the plume is a darker grey.
D. PLUME PERCEPTIBILITY PARAMETER AE
The final step in the quantification of plume perceptibility is the
specification of color differences—differences both in color and bright-
ness. In 1976 the Commission Internationale de 1'Eclairage (CIE) adopted
two color difference formulae by which the perceived magnitude of color
differences can be calculated. Color differences are specified by a
parameter AE, which is a function of the change in light intensity or
value (AL*) and the change in chromaticity (AX,Ay). AE can be considered
as a distance between two colors in a color space that is transformed in
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11
such a way that equal distances (AE) between any two colors correspond to
equally perceived color changes. This suggests that a threshold (AEg) can
be found to determine whether a given color change is perceptible.
r
Since the CIE could not decide between two different proposed formulae
for AE, both were adopted in 1976 as standard means by which color differ-
ences can be specified. These color differences, which are labeled
AE(I_*U*V*) and AE(L*a*b*), are calculated by the plume visibility code.
We have elected to plot AE(L*a*b*). A AE of greater than 20 indicates a
strong discoloration, AE's between 5 and 20 represent weak discoloration,
and with a AE Isss than 5, a plume would probably not be perceptible. It
is currently uncertain as to what the thresholds of perceptibility are in
terms of values of blue-red ratio, plume contrast, and AE.
E. SUMMARY
Figure 2 summarizes these qualitative interpretations of the quantita-
tive specifications of visibility impairment and may be used as a key to
Figures 3 through 7.
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1 2 * 6 10 20 40 60 100 ZGO
Location of Observer Downwind of Power Plant (km)
FIGURE 2. KEY TO PARAMETERS USED TO CHARACTERIZE
VISIBILITY IMPAIRMENT
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13
IV EFFECTS OF EMISSIONS, ATMOSPHEKll STABILITY, AND
SCATTERING ANGLE ON PLUME VISIBILITY IMPAIRMENT
Figures 3(a) through 3(i), presented at the end of this chapter,
illustrate calculated plume visibility impairment resulting from the hypo-
thetical, three-unit, 2250-Mwe, coal-fired power plant. For all of these
plots, the background ambient conditions are typical of those in nonurban
areas of the western United States: The background visual range is 130 km,
and the background ozone concentration is 0.04 ppm. The observer is assumed
to be situated 2.5 km from the plume centerline, at the indicated downwind
distances. See the key on page v and Table 1 for base conditions.
Four emission/formation scenarios are assumed and illustrated in each
of these figures:
(1) Normal NOX emissions (at the NSPS limit); 0.5 %/hr
sulfate formation (the base case).
(2) Normal NO emissions; no sulfate formation (equiva-
A
lent to the assumption of no SO^ emissions, or
complete flue gas desulfurization).
(3) No NO emissions; 0.5 %/hr sulfate formation
X
(equivalent to complete NO removal and no S0~
A C-
removal).
(4) No NO emissions; no sulfate formation (equivalent
A
to complete NO and SO- control except for fly ash
A t_
emissions).
Figures 3(a), 3(b), and 3(c) illustrate for a scattering angle of 45° (a
forward scattering case--sun in front of observer) the visibility impairment
parameters for Pasquill stabilities C, D, and E, respectively. Figures
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14
3(d), 3(e), and 3(f) show the same plots for a scattering angle of 90°; and
Figures 3(g), 3(h), and 3(i) show the impact for a scattering angle of 180°
(a backscatter case--sun behind the observer).
By comparing these nine figures, the following observations can be
made:
> Plume visibility impairment is greatest during stable
atmospheric conditions (Pasquill E). More stable
conditions or lighter winds (allowing less dispersion)
would result in still greater visibility impairment.
> The effect of the orientation of the sun relative to
the observer and plume (scattering angle) is chiefly
manifested in the relative brightness of the plume, as
indicated by plume contrast. In backscatter, the plume
is always darker than the background; in forward scatter,
when NO is not emitted, the plume is always brighter
X
than the background: In such a situation, more light
is scattered toward the observer when the sun is in front
of the observer (0 < 90°) than when the sun is behind the
observer (e > 90°).
> The impact of fly ash on visual range (see Case No. 4 in
these figures) is negligible, but is greatest (a 5 percent
reduction) during stable conditions, 1 km downwind (the
closest distance considered).
> The impact on visual range of sulfate formed in the atmo-
sphere from S02 emissions (see Case No. 3 in these
figures) is small, but increases with distance downwind
and with increasing stability, reaching a maximum of about
a 10 percent reduction for stable conditions (Pasquill E)
at the farthest distance considered (350 km).
> The impact of NOp on visual range is negligible for the
plume-observer distance assumed in these calculations
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15
(2.5 km). (This impact on visual range increases with
increasing plume-observer distance, as will be shown in
subsequent plots.)
Sulfate aerosol and fly ash (Case Nos. 3 and 4) have almost
no effect on discoloration, as indicated by the blue-red
ratio. However, it should be noted that sulfate plumes
(Case No. 3) are brighter (whiter) in forward scatter
and darker (greyer) in backscatter than the background
sky.
NOp formed in the plume has the most significant effect
on plume coloration and plume perceptibility, as indi-
cated by the blue-red ratio and AE. N02 is the dominant
colorant, though sulfate contributes slightly, in
backscatter situations.
For all scattering angles, sulfate aerosol will reduce
somewhat the N0? coloration, as evidenced by blue-red
ratio, because cf the masking effect of scattered light;
however, in backscatter only (e = 180°), sulfate contri-
butes to plume perceptibility, as evidenced by larger AE
values, because of its darkening effect (negative plume
contrasts).
The location downwind from the power plant, at which the
maximum discoloration occurs and at which the plume is
most perceptible, varies with the rate of plume dilution.
During well-mixed conditions [Pasquill C--see Figures
2(a), 2(d), and 2(g)], a plume would be most colored
(blue-red ratio < 0.9) and most likely to be visible
(AE > 5) at 10 to 15 km downwind. However, since AE = 5,
the plume would probably not be noticeable. During neu-
tral conditions [Pasquill D--see Figures 2(b), 2(e), and
2(h)], maximum plume coloration and perceptibility occurs
at about 25 km downwind. The blue-red ratio of about
0.82 and the AE value of 7 indicate that, at this dis-
tance, the plume would appear slightly yellowish; however,
-------
16
some people might not notice the plume at all. For stable
conditions [Pasquill E—see Figures 2(c), 2(f), and 2(i)],
the maximum discoloration (blue-red ratio = 0.78) occurs
at 40 km downwind and the plume would be perceptible
(AE = 10) to most people as a grey-yellow haze. Decreasing
plume coloration at distances beyond the maximum results
from plume dilution.
-------
17
80.0
x 50 To
§ <0.0
o
w
" 30.0
>
J 20.0
u
£ 10.0
o.o
1.1
(1) N8KNBL NBI EHJSSIBNS: 0.5 PERCENT/HR SULFSTC F8KHST1SH
(Z) NJKHBL H8I EKI3S18IN5: Hf SULFR7E F8KHBTI8H
(3) US N8X ENISSIPN5: 0.5 PEKCENT/HR SULFBTE FC^H
«i na S'BI EMISSIONS; m SULFOIE FPKMSTIBK
o.e
0.7
o.i
_-0.0
VI
CC
*-
z
S-o.i
UJ
L.a
-0.3
15.0
10.0
s.o
10 ro to so 100
DVNNHIND DISTANCE (Ml
300
(a) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 45° and Stability Class C
FIGURE 3. CALCULATED PLUME VISIBILITY IMPAIRMENT
-------
so.o
z 50.0
£ 10.0
^30.0
£ 20.0
u
t 10.0
0.0
1.1
gl.O
o
o.a
(1) HBRMHL N8X EHISSIBNS: 0.5 PERCENT/HR SULFR7E FBRHRTI8H
(2) NBRMSL NBX EMI3SIBNS: NB SULFflTE F0RHflTI3rj
(3) M* NflX EKIS3IBNS: 0.5 PERCENT/HR SULFRTE F0SHR1IBN
(4) KB H8X EMISSIBNS: NB SULFRTE FBRMRTI0N
0.7
o.i
_-o.o
0>
cc
S-o.i
-0.3
1S.C
10.0
5.0
0.0
10 20 40 SO 100
DIMMHINO DISTRNCE (KM)
200
(b) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 45° and Stability Class D
FIGURE 3 (Continued)
-------
19
60.0
z 50.0
§40.0
s
^30.0
>
5 20.0
u
Sio.o
0.0
1.1
£0.9
^
0.8
0.7
0.1
_-0.0
en
CE
(E
(1) N0RHflL NflX EHI5SI0NS; 0.5 PERCENT/HR SULFfiTE FBRHflTISN
12) N0RHRL N0X EHISSI0NS; N0 SULFflTE F0RHRTIPH
(31 N0 N0X EHISSIBNS; 0.5 PERCEHT/HR SULFflTE FPRMflTI3N
(4) N0 N0X EHISSI0NS; N0 SULFflTE F9RHfiTI0N
1-0.1
i
• -o.z
-0.3
1S.O
10.0
5.0
a.o
10 ZO 40
DWNMINO DISTANCE (KH)
200
(c) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 45° and Stability Class E
FIGURE 3 (Continued)
-------
20
60.0
x 50.0
>-
S 10.0
230.0
»
5 20.0
£ 10.0
0.0
1.1
2 0.9
O.t
8.7
.1
_ -0.0
5-0.1
u
-0.3
15.0
10.0
6.0
0.0
(1) NBRHflL NBX EHI3SI8NS; 0.5 PERCENT/HR SUlFflTE FBRHRTIBN
(2) NBRKflL NBX EHI3SIBN3; N8 SULFBTE F8RHSTI8N
(31 NB NBX EHISSIBNS: 0.5 PERCENT/HR SULFSTE FBRMflTIBN
(4) N« NBX EMISSIBNS: Ng SULFflTE FBRHBTIBN
10 20 40 60
DWNMINO DISTANCE (KM)
100
200
(d) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 90° and Stability Class C
FIGURE 3 (Continued)
-------
21
(1) NBRHBL NBX EHI3SIBNS: O.S PERCENT/HR SULFBTE FBRMRTI8N
(2) NBRHBL NBX EMISSIBH5; NB SULFBTE F8RMBTI8N
(3) NB NBJ EMISSIBN5: O.S PERCENT/HR SULFBTE FBRHBTIBN
(41 NB NBX EHISSI3N3: NB SULFBTE FBRMBTI0N
5.0 -
0.0
20 40
OI6TBNCE (KM)
zoo
(e) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 90° and Stability Class D
-------
22
60.0
z 50.0
y 40.0
2 30-° "
e 20.0
(1) NBRMHL NBX EHISSIBNS; 0.5 PERCENT/HR SULFSTE FBRMflTIBN
12! NBRHRL NBX EHISSIBKS! NB SULFRTE FBRHRTIBN
(3) NB NBX EHISSIBNS! 0.5 PERCENT/HR SULFRTE FBRHflTIBN
(4) MB NBX EMISSIBNS! NB SULFSTE FBRHRTIBN
0.0
1.1
Si.o
i
^0.9
^
n
0.8
_LJ_U-L
8
_-0.0
«rv
CE
1-0.1
ttl
*• -0.2
-0.3
15. 0
10.0
S.O
0.0
10 20 40
DWNNINO DISTRNCE (KM)
200
(f) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 90° and Stability Class E
FIGURE 3 (Continued)
-------
23
60.0
z SO.O
H 40.0
2 30.0
»
5 20.0
£10.0
0.0
1.1
•
§1.0
e
0.8
(1) NBRHflL NBX EHISSIBN3; 0.5 PERCENT/HK SULFRTE
(2) NBRHRL Ml EHISS18NS; Ng SULFRTE F0RHRTIBN
(3) N8 N8X EMISSIBNSi 0.5 PERCENT/HR SULFHTE FBRHflTIBN
(4) NB NBX EMISSIBNSi N8 SULFRTE FBRHflTIBN
0.8
.1
_-0.0
-o.i
-0.3
IS.O
I l i I I I I I
10.0
u
e
s.o
o.o
10 ZO 40
DiWNHINO DISTANCE
-------
60.0
i so-°
§ w.o -
^ 30.0 -
»
5 20.0
o
oe
It! to.o
0.0
24
(I) NBRHfll NiX EHI5SI8N": 0.5 PERCENT/HR SULFHTE FBRHflTIBN
12) NBRHRL N8X EHI5SIBNS: N8 SULFRTE FBRHHTI9N
(3) NB NBX EHISSIBNS: 0.5 PERCENT/HR SULFRTE FBRHfiTIBN
U) N8 NBJ EHISSTBNS: NB SULFRTE FBRHflTIBN
1.1
,.0
Q fl
°'8
0.8
,_ -o.o
in
cc
Of
S-o.i
kJ
I..,
-0.3
1S.O
10.0
5.0
0.0
I till!
10 eo 40
OIMNH1HO DISTANCE (KM)
60
ZOO
(h) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 180° and Stability Class D
FIGURE 3 (Continued)
-------
25
60.0
50.0
30'0
20.0
0.0
(1) NiRHHl Nil EHIS3I8N3; 0.5 PERCENT .'HR SULFHTE FBRHHTI8H
(21 HBRHHL Nil EMISSI8NS: N8 SULFATE FBRHRTI0N
(3) NB NBX EMIS3IBN3: 0.5 PEFCENT/HR SULFBTE FBRHflTlaN
(4) NB N8J EMISSIONS; N8 SULFHTE FBRHflTIBH
0.8
• -o.z
-0.3
15.0
10.0
lu
s.o
0.0
10 20 40 60
DfHNHIND 01STHNCE (KM)
100
200
(i) Hypothetical 2250-Mwe Coal-Fired Power Plant with
Light Scattering Angle of 180° and Stability Class E
FIGURE 3 (Concluded)
-------
26
EFFECTS OF PLUME OBSERVER DISTANCE, BACKGROUND
VISUAL RANGE, AND ATMOSPHERIC STABILITY
ON PLUME VISIBILITY IMPAIRMENT
Figures 4(a) through 4(p), at the end of this chapter, illustrate
plume visibility impairment as a function of downwind distance for three
different plume-observer distances (2.5, 5, and 10 km) for the permuta-
tions of:
> Atmospheric stability (Pasquill D and E).
> Power plant size (750- and 2250-Mwe).
> Background visual range (typical for the eastern
United States: 15 km; best for the eastern United
States: 30 km; typical for the western United
States: 130 km; and best for the western United
States: 200 km).
The base emission and ambient conditions were selected for all these
cases: typical NSPS emissions; 0.04 ppm background ozone; and 0.5 %/hr
sulfate formation. (Also see the key on p. v and Table 1 on p. 5.)
The effect of increasing atmospheric stability on visibility impair-
ment is, as previously mentioned, an increase in both the magnitude of
impairment and the distance downwind at which maximum impairment occurs.
Additional observations based on Figures 4(a) through 4(p) can be made:
> For given emissions and stability, the percent reduction
in visual range is not affected by the magnitude of the
background visual range.
> The percent reduction in visual range increases with
increasing plume-observer distance for two reasons.
First, as the plume diffuses, some of the plume material
-------
27
diffuses beyond the observer at a fixed distance from the
plume center!ine and is not within the given line of
sight. Second, plume NCL will have a greater effect on
visual range when plume discoloration is reduced owing to
plume dispersion.
Since visual range reduction is proportional to plume
sulfate flux, and since SO^-to-SO^ conversion is assumed
to be first-order, the impact on visual range of the
three-unit (2250-Mwe) plant is three times the impact of
the single-unit (750-Mwe) plant.
As the background visual range decreases and plume-
observer distance increases, the discoloration of the
plume becomes less pronounced because of the masking
effect of light scattered by the background aerosol. For
typical eastern United States conditions [see, for example,
Figure 4(b)], a plume would not be visible at all since
AE < 5; for typical western United States conditions [see,
for example, Figure 4(j)], a plume might be faintly visible
as a yellow haze (5 < AE < 10); however, coloration
decreases with increasing plume-observer distance.
The location downwind from the power plant at which maximum
discoloration occurs increases with increasing stability and
increasing plume-observer distance.
Plume perceptibility and coloration is more severe in areas
such as the nonurban western United States, where the back-
ground visual range is excellent. For the conditions inves-
tigated, plumes in the eastern United States would not be
perceptible.
Unlike visual range, plume discoloration and perceptibility
is not proportional to power plant emissions or size because
NO-to-NOp conversion is not linear and is diffusion-limited.
For example, Figure 4(n) indicates a maximum plume percepti-
bility AE value of 10 for the 2250-Mwe plant, while Figure 4(p)
-------
28
indicates that, under identical ambient conditions, the
maximum coloration impact of a 750-Mwe plant corresponds
to a AE of 5, more than one-third the impact of the three-
unit plant.
Discoloration and plume perceptibility would increase if a
light wind situation (u < 2 m/sec) occurred, or if the
plume were viewed along the plume axis or obliquely instead
of with the line of sight perpendicular to the plume axis,
as was assumed in these calculations.
-------
29
60. 0
z 50.0
^ 40.0
I
£90'°
>
£ 20.0
£lO.O
0.0
l.t
PLUHE-BBSEFVER DISTANCE
ID 2.5 KM
(2) 5.0 KM
(3) 10.0 KM
i I T"T"T"TT
0.8
'-O.I
-0.3
15.0
10.0
0.0
* 6 10 20 40 60 100
MHNH1ND DISTANCE (KM)
200
(a) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 4. EFFECT OF PLUME-OBSERVER DISTANCE
ON CALCULATED VISIBILITY IMPAIRMENT
-------
30
60.0
50.0
40.0
30.0
20.0
! 10.0
0.0
1.1
a
ll.O
S
l°-a
m
0.8
-0.0
ac.
t-
§-o.i
-0.2
-0.3
15.0
10.0
5.0
0.0
PLUHE-8B3EPVER OISTBNCE
ri) 2.5 KM
(2) 5.0 KM
(31 10.0 KM
I It 1 J L
10 20 40 60
OfUNWIND DISTANCE IKK)
100
200
(b) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
31
60.0
i 50-°
§ 40.0
O
UJ
^30.0
>
£ 20.0
u
a:
£ 10.0
o.o
PLUHE-863ER'"'EF DI3TRNCE
(1) J.5 KM
(2) 5.0 KM
(31 10.0 KM
0.8
0.7
O.I
. -0.0
'-0.1
• -0.2
-0.3
15.0
10.0
5.0
0.0
_t l i
10 20 40 $0
OiHNHINO DISTANCE (KM)
100
200
(c) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
60.0
32
DISTANCE
(II 2.5 KH
(21 5.0 KH
(31 10.0 KH
: 50.0 -
i
i 40.0 -
i
i
: 20.0 -
>
! lo.o -
o.o
1.1 -
0.7
0.1
_-0.0
en
tr
-------
33
60.0
z 50.0
i »0.0
o
UJ
^30.0
>
£ 20.0
u
£lO.O
0.0
1.1
a
I 1.0
O
IU
I 0.9
1
0.8
(1) 2.5 KH
(2) 5.0 KH
(3) 10.0 KM
DISTflNCE
I I I I I I
8:1
-0.0
-0.1
• -0.2
-0.3
15.0
10.0
S.O
0.0
I III
10 20 40 60 100
DIHNHIND DISTANCE (KH)
200
(e) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
60.0
34
PLUHE-963ERVER OI5TRNCE
(11 2.5 KM
(21 5.0 KM
(31 10.0 KH
gSO.O -
§ w.o
a
£
„•> 30-0 -
>
£ 20.0 -
u
I 10.0
0.0
1.1
OB
I 1.0
a
u
| 0.9
-j
aa
0.8
0.7
0.1
,.-0.0
i -o.i
-0.2
-0.3
15.0
10.0
5.0
i 111
10 ZO 40 60
DIHNHIND DISTANCE (KH)
100
200
(f) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
BO.O
z 50.0
s
§ 10.0
o
UJ
" 30.0
>
£ 20.0
u
£ 10.0
0.0
35
PLUME-aBSEn.ER Dl'TBNCE
(1) 2.5 KM
(2) 5.0 KM
(31 10.C KM
0.8
_-0.0
I -0.1
-0.2
-0.3
15.0
10.0
5.0
0.0
_J I I i
10 20 40
DIHNHIND DISTANCE (KM)
200
(g) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
36
60.
z 50.
B
§ «.
S
^30.
>
•T 20.
u
£ 10.
0.
(1) 2.5 KM
(21 5.0 KM
(31 10.0 KM
OISTfiNCE
0 -
0
0
0
a
o
1.1
1.0
-0.0
1-0.1
-0.2
-0.3
15.0
10.0
5.0
0.0
10 20 40 60
DWNHINO DISTANCE I KM I
100
200
(h) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
37
60.0
,,30.0
>
20.0
o.o
PLUHE-SB3ER»ER DI5TSMCE
(II 2.5 KM
(2) 5.0 KH
(3) 10.0 KH
0.8
"0'"
-0.!
-0.3
li.O
10.0
5.0
* 6 10 20 40 $0 100
OWNHINO DISTANCE (KH)
EDO
(i) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
38
60.0
z 50.0
i«.o
o
tu
£ 30-°
>
2 20.0
u
OE
£ 10.0
0.0
PLUME-3BSERVER DISTfiHCE
(1) 2.5 KM
(2) 5.0 KM
(31 10.0 KM
-0.0
'-0.1
-0.2
-0.;
15.1
10.0
5.0
0.0
10 20 40 60
DWNHIND DISTANCE (KM)
100
aoo
(j) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
39
60.0
: 50.0
10.0
30.0
20.0
10.0
0.0
1.1
>-
o
u
|0,
D
0.8
8.7
.1
_-0.0
en
S -o.i
E-S63ES.Ef; DISTfiKCE
(I) 2.5 KH
(2) 5.0 KH
(3) !0.0 KM
till
-0.2
-0.3
15.0
10.0
5.0
0.0
i i i
"\~-jS~g-
10 20 40 60 100
DMNMIND OISTRNCE (KM)
ZOO
(k) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
40
60.0
PLUHE-SBSEFVER DI5TRNCE
111 ?.5 KM
121 5.0 KM
(31 10.0 KM
z 50.0 -
s
| 40.0
o
UJ
^30.0
>
g 20.0
u
SIlO.O
0.0
1.1
1.0
0.8
8:1
-0.0
1-0.1
-0.3
15.0
10.0
5.0
10 20 40
DWNHINO DISTRNCE (KM)
60 100
200
(1) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
41
60.0
: 50.0
i
; fo.o
i
', 30.0
; 20.0
i
! 10.0
o.o
1.1
£1.0
O
u
|o,
oa
0.6
'-0.1
• -0.2
-0.3
1S.O
10.0
5.0
0.0
PlUME-flBSER'-EP OI3TSNCE
II! 2.5 KM
(2) 5.0 KM
(3) 10.0 KM
i i i i i
10 20 40 60 100
WMNMINO OrSTRNCE (KM)
200
(m) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
60.0
z 50.0
^ 40.0
o
UJ
* 30.0
£ 20.0
u
a:
" 10.0
0.0
1.1
CB
I 1.0
O
liJ
| 0.9
o
0.8
'-0.1
• -0.2
-0.3
1S.O
10.0
s.o
0.0
E-?B?ERVER DI3TSNCE
(1) 2.? KM
(2) 5.0 KM
(3) 10.0 KM
-I L
10 20 40 60 100
MHNHINO DISTRNCE I KM)
200
(n) Hypothetical 2250-Mwe Coal -Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability E
FIGURE 4 (Continued)
-------
43
60.0
: 50.0
I
40.0
30.0
20.0
10.0
0.0
FLUHE-SBjERVER OiSTBNCE
111 2.5 KM
(21 5.0 KM
131 10.0 KM
-0.0
-0.3
IS.O
10.0
5.0
0.0
> n o
10 20 40 60
DIMNHIND DISTRNCE (KN)
100
200
(o) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 4 (Continued)
-------
44
60.0
z SO.O
| ,0.0
^ 30.0
5 20.0
O£
£ 10.0
o.o
1.1
m
s
;•>..
0.8
_-0.0
1-0.1
• -0.2
-0.3
15.0
10.0
5.0
0.0
PLUHE-8B3ERVEK 01 STRIKE
(II 2.5 KM
(21 5.0 KM
(3) 10.0 KM
i ill
10 20 40 60
DfMNMINO DISTANCE (KM)
100
200
(p) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability E
FIGURE 4 (Concluded)
-------
45
VI EFFECT OF S02-TO-SULFATE CONVERSION RATE
ON VISIBILITY IMPAIRMENT
Figures 5(a) through 5(p) illustrate the effect of the rate of SCL-to-
sulfate conversion on visibility impairment. Three rates were evaluated:
5, 0.5, and 0 percent per hour.* The most significant effect of fast sulfate
formation (5 percent/hr) is the dramatic reduction in visual range, partic-
ularly at far downwind distances; for example, the 2250-Mwe power plant would
cause a 25 percent reduction in visual range as shown in Figure 5(a) at
100 km downwind during ieutral conditions (Pasquill D), and greater than
a 60 percent reduction, ai shown in Figure 5(b), during stable conditions
(Pasquill E). In some instances (particularly for the eastern U.S. cases)
the plume becomes less perceptible with the assumptions of faster sulfate
formation because of the color-masking effect of additional scattered
light; however, in other cases (notably under the western U.S. conditions
with good background visual range), the larger sulfate concentrations
resulting from fast SOp-to-sulfate conversion will cause a more notice-
able grey plume or haze.
* See key on p. v and Table 1 on p. 5 for base conditions.
-------
46
60.0
i 50-°
^ 40.0
o
IfcJ
£30.0
X
u
I 10.0
0.0
1.1
£1.0
O
U
j 0.9
n
0.8
0.7
0.1
.-0.0
1-0.1
• -0.2
-0.3
1S.O
10.0
5.0
SULFflTE F8RHSTI8N RSTE
(1) 5.0 PERCENT/H6UR
(2) 0.5 PERCENT/HBUR
(3) 0.0 PERCENT/H8UR
=8=5=
8 3
10 20 40
OIHNHIND DISTANCE (KH)
60 100
200
(a) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 5. EFFECT OF SULFATE FORMATION ON CALCULATED
PLUME VISIBILITY IMPAIRMENT
-------
60.0
z 50.0
m
§ 40.0
o
IkJ
* 30.0
>
5 20.0
2
" 10.0
0.0
1.1
I i.o
3
i 0-9
i
0.8
_-0.0
1-0.1
-0.2
-0.3
15.0
10.0
S.O
0.0
47
SULFflTE FBRHRTIBN FflTE
(1) 5.0 PERCENT/H8UR
(2) 0.5 PERCENT/HHUR
(3) 0.0 PERCENT/H8LIR
10 20 40 60
DWMMIMD DISTANCE (KM)
100
200
(b) Hypothetical 2250-Mwe Coal Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
60.0
50.0
40.0
30.0
20.0
! lo.o
0.0
^0.9
0.8
S-o.i
-0.2
-0.3
15.0
10.0
5.0
0.0
48
SULFPTE F9RHMTI3H RflTE
(1) 5.0 PERCENT.'H8UR
(2) 0.5 PERCENT/HBUR
(3) 0.0 PERCENT/HBUR
10 20 40
DIMNUIND DISTANCE (KH»
60
100
200
(c) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
49
SULFSTE F8PHRTISN PflTE
(11 5.0 PERCENT/HBUR
(2) 0.5 PERCENT/HBUR
(3) 0.0 PERCENT/HBUR
60.0
z 50.0
y 40.0
S
z
u
K
£ 10.0
0 o
1.1
I 1.0
S
iO.9
a
0.8
8.7
.1
en
K
u
10.0
kl
c
UJ
o
S.O
0.0
-
-
-
-
_
-
l i i 1 | f i I
-
-
1 Z 46
-^^^
1 — i — 3r
1 t i 1 i t t I
10 20 40 60 1
DiHHHIND DISTRNCE (KM)
^
V
1 :
00 SOD
(d) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
50
60.0
x 50.0
§40.0
^30.0
>
£ 20.0
u
DC
" 10.0
0.0
1.1
VI
ll.O
0.8
0.7
0.1
-0.0
-0.1
-0.2
-0.3
15.0
10.0
5.0
0.0
5ULFSTE FBRHRTI8N RflTE
(11 5.0 PERCENT/HOUR
12) 0.5 PERCENT/HanR
(3) O.fl PERCENT/H81.IR
2-
i i i i
10 20 40 60
MHNM1ND DISTANCE
-------
51
60.0
a 50.0
Q)
£ 40.0
UJ
" 30.0
>
£ 20.0
u
DC
£ 10.0
0.0
1.1
SULFflTE FBRHSTIBN RflTE
(1) 5.0 PERCENT/H0UR
(2) 0.5 PEBCENT/H0UR
(3) 0.0 PERCENT/HflUR
0.8
-0.0
'-O.I
-0.2
-0.3
15.0
10.0
5.0
0.0
_J i i till
10 20 40 60
MMNHINO DISTANCE (KM)
100
EDO
(f) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
60.0
52
SULFPTE FSRMSTI3N RSTE
(1) 5.0 PERCENT/HBIIB
(2) 0.5 PERCEHT/H8IIR
13) 0.0 PERCENT/HBUB
50.0 -
10.0 -
30.0 -
20.0 -
10.0
0.0
1.1
I
I 1.0
t
I 0.9
i
>
o.a
0.7
o.i
• -0.2
-0.3
15.0
10.0
5.0
10 20 40
DflHNHINO DISTRNCE (XH)
60
100
200
(g) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
53
60.0
: 50.0
i
40.0
30.0
20.0
10.0
0.0
1.1
a
I 1.0
O
UJ
IT
^0.9
dQ
0.8
_-0.0
i-o.i
-0.2
-0.3
is.a
10.0
5.0
o.o
SULFaTE FBFHfiTlBN nflTE
(1) 5.0 PERCENT.'HSUR
(2) 0.5 PERCENT/H0UR
(3) 0.0 PERCENT/HBUR
i a a
10 20 40
DIMNHINO DISTRNCE (KM)
60
100
200
(h) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
54
60.0
z 50.0
I 40.0
o
U
£ 30.0
>
£ 20.0
u
£10.0
o.o
1.1
5ULFSTE FBRMfiTIBN RBTE
(II 5.0 PERCENT/HSIW
(21 0.5 PERCENT.'H8UR-
131 0.0 PERCENT/HBUR
_1 _
. -0.0
i -o.i
-0.2
-0.3
15.D
10.0
5.0
10 ZO 40
MHNHtND DISTANCE (KHJ
SO
100
200
(i) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
60.0
z 50.0
a
§ 40.0
o
UJ
^30.0
>
5 20.0
o
Sio.o
0.0
55
SULFflTE F8RMHTISN FRTE
(1) 5.0 PERCENT-"HaUR
(2! 0.5 PERCENTfHBUP
(3) 0.0 PERrENT/HflUR
0'9
0.8
0.7
0.1
-0.0
1-0.!
-0.2
-0.3
1S.O
10.0
5.0
0.0
10 20 40 60
DINNNINO DISTANCE (KM)
100
200
(j) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
56
60.0
| 50.0
§ w.o
o
u.
OK
„ 3C.O
»
£ 20.0
u
K
£ 10.0
0.0
1.1
a
ii.o
a
UJ
I 0.9
«Q
0.8
8:1
_-0.0
«
cr
S-o.i
SULFSTE FBRHBTI0N RflTE
II) 5.0 PERCENT/HBUR
12) 0.5 PERCENT/HBUR
(3) 0.0 PERCENT/HBUR
-0.3
1S.O
I 1 I I I I I I
10.0
5.0
2 4 6 10 20 40 60 100 200
DWMUIND DISTANCE (KM)
(k) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
SUIITTE FERHP.TICN RR1C
(1) 1.0
(31 O.C F'LJ.'CLl'T/iiOUl
6U.O
r ro.o
t
'•i «. o
o
r- 2Q.o
(' 10.0
o.o
1.1
I 1.0
a
it'
K.
?
0.8
8:1
-c.o
S-o.i -
"'T=^=r-—~i •-—^ T..J---'—^ <' -w^Bt*-.v,T '«»;i...3.?7'£^si^n;i^i-.Ji
..'_ J 1 !..-.' --I-.
-0.3
15.0
10.0
s.c
0.0
-i-3-
— 1-
* E 10 EC 4C 60 100
MUNKINO CISTRHCE IKH)
200
(1) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
58
60.0
0.0
5ULFHTE FBRMHTIBN fifiTE
(!) 5.0 PERCENT/HBUR
(2) 0.5 PEFCENT/H8UP
(3) 0.0 PERCENT/'H8IJP-
10 20 40
DBHNM1NC DISTANCE (KHJ
(m) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
59
60.0
2 50.0
is
§ 10.0
O
IU
a;
.r. 3fJ-0
>
£ 20.0
LJ
tc
£ iu.o
o.o
SULFRTE FgRHflTiaii RflTE
111 5.0 FEPrENT-'HBUR
12) 0.5 FEFCENT.'HBUR
(31 0.0 PERCENT-HBIjR
.-0.0
1-0.1
-0.2
-0.3
15.0
10.0
5.0
t I I t l l
10 20 40
OWN WIND DISTANCE IKH)
100
200
(n) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability E
FIGURE 5 (Continued)
-------
60
6P.O
z 50.0
s
£ 40.0
O
UJ
* 30.0
>
z 20'°
o
oc
£ iQ.Q
0.0
1.1
d
I i.o
o
UJ
cr
^0.9
iD
0.8
0.7
0.1
'0'0
-o.i
-0.2
-0.3
15.0
10.0
5.0
0.0
SULFPTE FBBMPTI0N FflTE
(11 S.O PERCENT,'HflUR
(2) 0.5 PERCENT,'HeUB
(31 0.0 PERCENT ,-H0»R
10 20 TO 60 100
DBMNMIND DISTRNCE (KM)
200
(o) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 5 (Continued)
-------
60.0
z 50 0
a
y 40.0
o
LJ
ex.
30. 0
520.3
a
£ 10.0
0.0
1.0
61
SUIFRTE FSRHSTISH RSTE
(1) 5.0 PERCENT-'HIIUR
12) 0.5 PERCENT/H0UR
131 0.0 FE.RCENT/H8UR
0.7
0.1
-0.0
-0.3
15.0
10.0
5.0
10 20 40
MHNHIND DISTANCE (KM)
60
100
200
(p) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability E
FIGURE 5 (Concluded)
-------
62
VII EFFECT OF N02 FORMATION RATE DUE TO DIFFERENT
BACKGROUND OZONE CONCENTRATIONS ON
VISIBILITY IMPAIRMENT
The effect of different assumptions about the background ozone concen-
tration, which affects the conversion of colorless NO to the red-brown NOp
gas in power plant plumes, is illustrated in Figures 6(a) through 6(p).
Three background ozone concentrations were evaluated: 0.12, 0.04, and
0.00 ppm.* An ozone concentration of 0.04 ppm is typical of many nonurban
areas, while 0.12 ppm is typical of polluted areas where photochemical
reactions among NO and reactive hydrocarbon emissions cause ozone forma-
/\
tion. With no background ozone, only about 10 percent of NO emissions
A
are converted to NOp (resulting from the reaction of NO with Op). Note
that increased NOp concentrations have almost no effect on the visual
range, but significantly increase the coloration and the perceptibility
of plumes. For example, Figure 6(j) shows that, with a background visual
range of 130 km and an ozone concentration of 0.12 ppm, the plume percep-
tibility parameter AE approaches a value of nearly 15. It should be
noted, however, that a high ozone concentration would not likely coincide
with a high visual range.
* See key on p. v and Table 1 on p. 5 for base conditions.
-------
63
60.0
z 50.0
s
i 10.0
o
UJ
"lO.O
>
£ 20.0
o
S lo.o
0.0
1.1
n
I 1.0
O
UJ
| 0.9
_j
n
0.3
0.7
0.!
-0.0
S-o.i
• -0.2
-0.3
15.0
10.0
5.0
0.0
BZ8HE CeUCEM
(1) 0.12 FPK
(2) 0.04 PPM
(3) 0.00 PPH
10 20 40
08MNMIND DISTANCE IKM)
100
200
(a) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 6. EFFECT OF BACKGROUND OZONE ON CALCULATED
PLUME VISIBILITY IMPAIRMENT
-------
60.0
: 50.0
40.il
30.0
20. 0
10.0
0.0
1.1
B
I 1.0
1
I0-9
>
0.8
64
8ZBHE rflNCENTRflViBN
111 0.12 PFH
121 O.M PPH
(3) 0.00 PPH
I I
-0.3
15.0
10.0
5.0
10 20 40 60
DMNUIND DISTANCE (KH)
100
200
(b) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
65
in 0.12 PPM
(Z) 0.0" PPM
131 O.fiO PPH
60.0
i 5°'°
^ 10.0
E
oc
£ 20.0
u
K
SI 10.0
O.Q
1.1
t-
ff 1 0
o
UJ
DC
=>
ID
0.8
8.7
.1
in
a
a:
1-0.1
Z)
"--0.2
-0.3
15.0
10.0
UJ
t-
IU
0
S.O
0.0
-
_
_
_
"
-
_ , , , ,^u
-
-
1 Z 46
, __
i i i i l i i i
0 £0 40 60 1
DfMNMIND DISTANCE (KM)
i i
00 200
(c) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
60.0
z 50.0 -
03
* 30.0 -
£20.0
U
QC
£ 10.0
G.O
66
BZoNE raNCES-T
(11 0.12 FPH
12) 0.04 PPM
(31 0.00 PPH
1-0.1
-0.2
-0.3
i i t i i ._i_.j_
10.0
s.o
10 20 40
DIHNUIND DISTRNCE IKM)
^oo
(d) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
67
60.0
: 50.0
40.0
30.0
20.0
10.0
0.0
1.0
0.8
0.7
O.I
-0.0
BZ0NE
(1) 0.12 PPM
12) 0.01 PPM
(3) 0.00 PPM
I T-
S-o.i
-0.3
15.0
10.0
10 SO 40 60
DMNMIND DISTANCE (KMI
100
EC3
(e) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
68
60.0
BZBNt CSNCENTFPITISN
til 0.12 PPM
(?) 0.04 PPH
(31 0.00 PPM
z 50.0 -
s
§ 40.0 -
o
UJ
DC
„, ?0.0 -
»
^ 20.0 -
o
K
£ 10.0 -
0.0
1 1111
1.0
0.8
0.7
0.1
-0.0
'-0.1
-0.3
15.0
10.0
5.0
0.0
i I I i I I
i i i i i i i
10 20 40
DMNHIND DISTANCE (KM)
100
(f) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
69
60.0
=: 50.0
G]
§ 10.0
a
UJ
a:
o-, 30-0
>
2 20.0
CJ
£ 10.0
0.0
1.1
BZSNE ,-0NrEWT
tl) 0.12 PPM
12) 0.01 PPM
13) 0.00 PPM
0.8
-0.0
1-0.1
-0.2
-0.3
1S.O
10.0
s.o
o.o
10 20 40
D8HNHINO DISTANCE (KM)
60
100
200
(g) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
70
60.0
8Z3NE CBhCENT
(II 0.!2 PPM
(21 0.04 PPM
(31 0.00 PPM
z 50.0 -
01
§ 40,0 -
o
LkJ
K
co 30-0 -
>
£ 20.0 -
u
£ 10.0
0.0
0.8 -
-0.0
1-0.1
• -0.2
-0.3
15.0
10.0
S.O
0.0
10 ZO 40 60
OiHNWIND DISTANCE IKH)
100
ZOO
(h) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Eastern Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
71
60.
z 50.
ai
2*0.
D
UJ
Q£
jo 30.
>
-20.
u
z
a! 10.
0.
BZBNE
111 0.12 PPM
(2) 0.04 FPH
(31 0.00 PPM
-1 ! I I I 1
1.1
-0.1
-0.2
-0.3
15.0
10.0
5.0
" 1 i 4 6 10 20 40 60 100 ECO
OMNHIND DISTANCE
(i) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
72
60.0
BZBNE CBNCENTRPTIBN
111 0. 1Z PPM
(2) 0.04 PPM
13) 0.00 PPM
| 50.0 -
§ 40.0 -
o
LJ
* 30.0 -
>
£ 20.0 -
u
CE
a! 10.0 -
0.0
1.0 -
1-0.1
-0.2
-0.3
15.0
10.0
5.0
0.0
10 20 40
DtMNHINO DISTRNCE (KM!
100
200
(j) Hypothetical 2250-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
73
60.0
z 50.0 -
«
§10.0 -
5 20.0
u
£ 10.0
0.0
BZBNE L8HCENTRHTI8N
(1) 0.12 PPM
(2) 0.04 PPM
13) 0.00 PPK
0.7
0.1
. -0.0
1-0.1
-0.2
-0.3
15.0
10.0
s.o
o.o1-
10 20 40 60
DIHNHIND DISTANCE (KM)
100
200
(k) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
60.13
: SO.O -
I
; 4o.o -
5 20.
cj
oe
£ 10.
o.
74
BZBNE CBNCENTRflTIBH
(1) 0.12 PPM
(21 0.04 PPH
(31 0.00 PPM
1.0
0.8
. -0.0
\ -0.1
-0.2
-Q.3
15.0
10.0
S.O
6 10 20 40 SO 100
DfHNHINO DISTANCE (KM)
200
(1) Hypothetical 750-Mwe Coal-Fired Power Plant; Typical
Western Ambient Conditions with Pasquill Stability E
FIGURE 6 (Continued)
-------
75
60. a
z 50.0
H»
§ w.o
o
UJ
^30.0
>
2 20.0
u
Qt
£ 10.0
0.0
l.O
0.8
8HBHE .rONrENT
(1! 0.12 FFM
(2) 0.04 PPM
(31 O.OC PPM
1 ii 3i
-0.3
15.0
10.0
till
10 SO 40 60
DIMNHIND DISTHNCE (KM)
100
?00
(m) Hypothetical 2250-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
76
60.0
BJSHE CBNCENTBfiTIBN
(II 0.\Z PPM
121 0.01 FPH
(31 0.00 PPM
z 50.0 -
s
§ 10.0 -
O
LJ
" 30.0 -
>
£ 20.C -
-------
77
BO.O
z 50.0
ea
^ 40.0
o
uj
,„ 30.0
»
£ 20.0
u
K
£ 10.0
0.0
I 1.0
J
I
I 0.9
I
I
0.8
BZBNE "SNC^NT
(1) 0.12 PPM
(2) 0.04 FPH
(3) 0.00 PPM
-0.3
15.0
10.0
5.0
=T=
10 20 40 60
09HNHIHD DISTANCE IKM)
100
200
(o) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability D
FIGURE 6 (Continued)
-------
78
60.0
z 50.0
s
§ 40.0
O
tu
^30.0
>
£ 20.0
u
£ 10.0
0.0
1.0
0.8
0.7
0.1
-0.0
1-0.1
-0.3
15.0
10.0
BZSHE C3NOEHTRFITI8N
!11 0.12 PPM
[21 O.CU FFH
(3) 0.00 PFM
i i t
i i i I l
10 20 40 60 100
08HNHINO 01 STANCE (Ml
200
(p) Hypothetical 750-Mwe Coal-Fired Power Plant; Best
Western Ambient Conditions with Pasquill Stability E
FIGURE 6 (Concluded)
-------
79
VIII A SUMMARY OF TYPICAL VISIBILITY IMPAIRMENT
CAUSED BY POWER PLANTS IN THE EASTERN
AND WESTERN UNITED STATES
We have rearranged the plots shown in different figures to compare on
a single plot the visibility impairment caused by power plant plumes under
typical eastern and western U.S. ambient conditions, where background vis-
ual ranges are poor and excellent, respectively. Figures 7(a) through 7(h)
compare eastern and western visibility impacts for the permutations of:
> Atmospheric stability (Pasquill D and E).
> Power plant size (750- and 2250-Mwe).
> Typical and best background visual range.*
These plots indicate that at the assumed 5 km plume-observer distance the
discoloration of power plant plumes is not likely to be perceptible in the
eastern United States, where a typical background visual range is 15 km
(9 miles); but in the nonurban areas of the western United States, where a
typical background visual range is 130 km (80 miles), plumes from large
power plants are likely to be perceptible as a yellowish (or possibly brown)
haze.
See key on p. v and Table 1 on p. 5 for base conditions.
-------
(I) ERSTERN U.S. IBflOGFflUND VISIBILITY = IS !>"
(2) WESTERN U.S. IBflCKGRtUmO 'ISIBILITY = ISO
60.0
z SO.O
O>
y 10.0
o
£
,,,30.0
>
Z 2°'°
(J
£ 10.0
o.o
1.1
luo
O
UJ
^ 0.9
_l
CQ
0.8
8:1
. -0.0
3-Q.i
•• -0.2
-0.3
1S.O
JO.O
6 10 20 40 60 100
MMNMIND OISTRNCE (KH>
£00
(a) Hypothetical 2250-Mwe Coal-Fired Power Plant;
Typical Visibility with Pasquill Stability D
FIGURE 7. COMPARISON OF PLUME VISIBILITY IN THE
EASTERN AND WESTERN UNITED STATES
-------
60.0
z 50.0
o
§ 40.0
O
UJ
tt
,,-, 50. 0
>
£ 20.0
o
vc
t 10,0
0.0
81
(II EASTERN II S fBflrhC-Reii'ND "I'IBILITV = 1?
(2) WESTERN l.l 5. rBflCKGRSUNIj «I5IBIL IT', = 130
0.8
0.7
0.1
,_ -0.0
i-0.1
• -0.2
-0.3
15.0
i ill
10.0
5.0
* 6 10 20 40 60 100
DIHNHIND DISTANCE (KH)
200
(b) Hypothetical 2250-Mwe Coal-Fired Power Plant;
Typical Visibility with Pasquill Stability E
FIGURE 7 (Continued)
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82
(1) EBSTERN II S. f6flCKn*0l'tJC -I-IPILITY - IS Hi;
(2) WESTERN U.S. IBRChGRBUND "I3IBILITY = HO <•<•••
50.0
10.0
13.0
0.0
§:I
-0.0
-0.1
• -0.2
-0.3
15.0
10 SO 40 60
DWNHINO DISTANCE 'KM)
too
JGC
(c) Hypothetical 750-Mwe Coal-Fired Power Plant;
Typical Visibility with Pasquill Stability D
FIGURE 7 (Continued)
-------
Ill EH3TEKN il ". ;pfl.-Kr,R(IUHO »!S!BILIT" - 15 k
(2) WESTERN LI.3. iBHCKuRBUND M5I6ILITY = 130
60.0
z 50.0
20.0
)
10.0
0.0
,0.9
§:?
-0.0
S-o.i
-0.2
-0.3
1S.O
10.0
5.0
10 cO 40 60
DiWNHIND DISTANCE
100
(d) Hypothetical 750-Mwe Coal-Fired Power Plant;
Typical Visibility with Pasquill Stability E
FIGURE 7 (Continued)
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84
60.0
z 50.0
B
I 40.0
o
LU
* 30.n
>
£ 20.0
(_)
DC
£ 10.0
0.0
(II ER3TERN U.S. IBBCKGRBUNO 'I^IBILITT - 70 K'-
(2) WESTERN U.S. (8RCKGRBUHD «ISIBILITV = 200 r«l
0.8
S-0.1
-0.3
15.0
10.0
5.0
4 6
10 20 40 60
DtMMHIND DISTANCE (KM)
100
EDO
(e) Hypothetical 2250-Mwe Coal-Fired Power Plant;
Best Visibility with Pasquill Stability D
FIGURE 7 (Continued)
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85
60.0
z 50.0
o
§10.0
o
LJ
o:
„-, ^.0
>
£ 20.0
u
K
£! 10.0
O.o
5 i.o
a
lu
tr
J.0.9
=
_»
CD
0.8
-0.0
1-0.1
• -0.2
-0.3
15.0
10.0
S.O
0.0
(11 EXTERN U.S. iBqcKGRPIIHD «I3IBIL!TY - 50 r
(?} WESTERN U.S. iBSCkC-l!0UHO ''ISIBILITi = 200
10 SO 40 SO
MMNHIND DISTANCE
-------
86
60.0
i so-°
„-, 30.0
£ 20.0
u
£ 10.0
0.0
1.1
s
I 1.0
o
Ul
1 0.9
_J
a
0.8
0.7
0.1
-0.0
-0.1
-0.2
-0.3
IS.Q
10.0
5.0
(11 EBSTERN U.S. IBRirKGRlUND -ISiBILlTV = 30 «
12) HE5TEFH U.S. IBPCKGRBUNO VISIBILITY - 200
t I . i i i l
10 20 40 60
DtMNHINO DISTANCE (KH)
100
200
(g) Hypothetical 750-Mwe Coal-Fired Power Plant;
Best Visibility with Pasquill Stability D
FIGURE 7 (Continued)
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87
60.0
z 50.0
B)
§ 10.0
O
U
0£
„*<> 0
s
£ 20.0
(J
£ 10.0
0.0
(!) EB3TERH 11.5. IBflCKCFBUHD vmFILITT - ^0 KM:
(21 WESTERN U.'. IBBCKGFBUNO V15IBILITY = 200 -H)
0.7
0.1
-0.0
-0.2
-0.3
15.0
10.0
5.0
0.0
10 20 40 60
DiHNHINO DISTANCE (KH)
100
200
(h) Hypothetical 750-Mwe Coal-Fired Power Plant:
Best Visibility with Pasquill Stability E
FIGURE 7 (Concluded)
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IX SUMMARY AND CONCLUSIONS
We briefly summarize the most important conclusions drawn from this
analysis of power plant plume visibility impairment as follows:
> The most significant reduction in visual range due to
power plant emissions occurs because of secondary
aerosol formation (e.g., sulfates and nitrates), par-
ticularly at large downwind distances more than 100 km
from the power plant. For new plants, fly ash emis-
sions must be controlled so that stack opacity is no
greater than 20 percent in order to meet NSPS limits
and, therefore, fly ash emissions have a small effect
on visual range.
> Plume discoloration (plume blight) is of particular
concern and is caused primarily by N02 formed by reac-
tions in the atmosphere with 0? and 0~ from NO emissions.
C- O A
Discoloration will be more perceptible under clear back-
ground conditions (a good background visual range) during
stable conditions with high background ozone concentra-
tions. In certain circumstances, fly ash and sulfate will
contribute somewhat to discoloration and plume percep-
ti bi 1 i ty.
> Reductions in visual range caused by 750- and 2250-Mwe
coal-fired power plants meeting NSPS will be small (< 10
percent) for average ventilation conditions and SO^-to-
sulfate conversion rates of 0.5 percent/hr.
> Reductions in visual range could be significant (> 25
percent) when conditions are such that sulfate is rapidly
formed, during poor plume dispersion conditions (e.g., with
light winds, stable air), or if the regional effects due
to several sources are considered.
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89
Atmospheric discoloration caused by 2250-Mwe coal-fired
power plants will be perceptible as a white, grey, yellow,
or brown haze, particularly in areas with excellent back-
ground visibility, and during stab'le conditions when plume
dispersion is poor.
Plumes from power plants located in the eastern United
States are not likely to be perceptible because of the
typically low background visual range; in nonurban areas
in the western United States, plumes from large coal-fired
power plants will be perceptible at times, even as far as
100 km downwind.
Visibility impairment will be greater than indicated here
when plume dilution is poor under stable, light wind condi-
tions, or when plumes are viewed along the plume centerline
or obliquely. Also, if emission rates and particle size
distributions are different from those assumed here, visi-
bility impairment will be different. More detailed analyses
based on appropriate emission, meteorological, and ambient
conditions are needed to evaluate fully the visual impact of
a given source.
We suggest that the user of this document exercise caution
in applying these results to specific power plant analyses.
These results are idealized cas s for specific emission,
meteorological, ambient background, and viewing conditions
based on a model that has not yet been validated.
-------
90
REFERENCES
Carpenter, S. B., et a^ . (1971), "Principal Plume Dispersion Models: TVA
Power Plants," J. Air Poll. Contr. Assoc.. Vol. 21, pp. 491-495.
Federal Register (1976), "Regulations on Standards of Performance for New
Stationary Sources," 41(111): 23059.
Husar, R. B., et al. (1978), "Sulfur Budget of a Power Plant Plume," Atmos.
Environ., Vol. 12, pp. 549-568.
Smith, T. B., et al. (1978), "Transport of S02 in Power Plant Plumes: Day
and Night," Atmos. Environ., Vol. 12, pp. 605-611.
Whitby, K. T., and G. M. Sverdrup (1978), "California Aerosols: Their
Physical and Chemical Characteristics," to be published in the ACHEX
Hutchinson Memorial Volume, Particle Technology Laboratory Publication
Number 347, University of Minnesota, Minneapolis, Minnesota.
-------
91
TECHNICAL REPORT DATA
fl'lcesc read lii±Lr.• /TITMC' lic/urc c
. REPORT NO.
EPA-450/3-78-110a,b,c
2.
. TITLE AND SUBTITLE
THE DEVELOPMENT OF MATHEMATICAL MODELS FOR THE
PREDICTION OF ANTHROPOGENIC. VISIBILITY IMPAIRMENT
3. RECIPIENT'S ACCECSI Off NO.
6. REPORT DATE
November 1978
6. PERFORMING ORGANIZATION CODE
AUTHORIS)
D. A. Latimer, R. H. Bergstron, S. R. Hayes, M. K. Liu,
J. H. Seinfeld, G. 2. Whitten, M. A. Wojcik, M. J. Hillye
8. PERFORMING ORGANIZATION REPORT NO.
EF78-68A,B,C
PERFORMING ORGANIZATION NAME AND ADDRESS
Systems Applications, Incorporated
950 Northaate Drive
San Rafael, California 94903
IQ. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
EPA 68-03-3947 and 68-02-2593
2. SPONSORING AGENCY NAME AND ADDRESS
U, S. Environmental Protection Agency
Waterside Mall
401 M Street, S.W.
Washington, D.C. 20460
13. TYPE OF REPORT AND PERIOD COVERED
Final Report: 10/77 to 9/78
14. SPONSORING AGENCY CODE
EPA-OPE/OAQPS
5.SUPPLEMENTARY NOTES
6. ABSTRACT
This report describes a nine-month study to recommend and develop models that pre-
dict the contribution of man-made air pollution to visibility impairment in federal
Class I areas. Two models were developed. A near-source plume model based on a
Gaussian formulation was designed to compute the impact of a plume on visual range
and atmospheric coloration. A regional model was designed to calculate pollutant
concentrations and visibility impairment resulting from emissions from multiple
sources within a region with a spatial scale of 1000 km and a temporal scale of
several days. The objective of this effort was to develop models that are useful
predictive tools for making policy and regulatory decisions, for evaluating the
impacts of proposed new sources, and for determining the amount of emissions reduc-
tion required from existing sources, as mandated by the Clean Air Act Amendments
of 1977. Volume I of this report contains thf main text; Volume II contains the
appendices; Volume III presents case studies of power plant plume visual impact for
a variety of emission, meteorological, and ambient background scenarios.
7.
KEY WORDS AND DOCUMENT ANALYSIS
b.JOENTIFIERS/OPEN ENDED TERMS c. COSATI I'icld/Group
DESCRIPTORS
Air quality modeling
Visual range
Atmospheric discoloration
Power plants
IB. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
13. SECURITY CLASS (flatKvpzrt)
UNCLASSIFIED
20. SECURITY CLASS (Tlia puns)
UNCLASSIFIED
;?
ill.
22. PRICE
Vol. Ill—91
farm JJ20-I (».?3)
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