Draft Final Report
POWER PLANT IMPACTS ON AIR QUALITY
AND VISIBILITY: SITING AND
EMISSION CONTROL IMPLICATIONS
EF78-148
December 1978
I'K'KI'AK'KI) liY
SYSTEMS APPLICATIONS.
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Draft Final Report
POWER PLANT IMPACTS ON AIR QUALITY
AND VISIBILITY: SITING AND
EMISSION CONTROL IMPLICATIONS
EF78-148
December 1978
Prepared for
U.S. Environmental Protection Agency
Office of Planning and Evaluation
401 M Street, S.W.
Washington, D.C. 20460
by
Douglas A. Latimer
Systems Applications, Incorporated
950 Northgate Drive
San Rafael, California 94903
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DISCLAIMER
This report has been reviewed by the Office of Planning and Evaluation,
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 comercial products constitute endorsement or recommendation for use.
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ACKNOWLEDGMENTS
We wish to thank Dave Shaver of the EPA for his guidance and Gary
Lundberg of SAl for his work on producing the computer plots.
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CONTENTS
DISCLAIMER .
ACKNOWLEDGMENTS iii
LIST OF ILLUSTRATIONS vi
LIST OF TABLES viii
I INTRODUCTION i
II SUMIIARY AND CONCLUSIONS 3
A. Air Quality Impacts Caused by Individual Power Plants . . 3
B. Visibility Impairment 5
C. Air Quality Constraints on Power Plant Siting 6
D. Cumulative Regional Impacts 7
E. Implications for Power Plant Emission Control 8
F. Research Needs 9
III BASES FOR CALCULATIONS 11
A. Emission Conditions 11
B. Air Quality and PSD Standards 13
C. Meteorological Scenarios and Modeling Approaches . . . . 14
D. Visibility Impairment 18
1. Parameters That Characterize Visibility Impairment . 19
2. Assumptions Used in the Model Calculations 21
IV IMPACTS OF INDIVIDUAL POWER PLANTS AND THEIR IMPLICATIONS
FOR EMISSION CONTROL AND SITING 24
A. Impacts on Ground-Level Air Quality 24
B. Implications of PSD and Alternate SO 2 Emission
Controls on Power Plant Siting 25
C. Visibility Impairment 36
1. Effect of SO 2 Emission Rates on SO, Fluxes and
Concentrations 37
2. Effect of NOx Emission Rates on NOx Fluxes and
Concentrations 43
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IV IMPACTS OF INDIVIDUAL POWER PLANTS AND THEIR IMPLICATIONS
FOR EMISSION CONTROL AND SITING (Continued)
3. Effect of S02 Emission Rates on Visibility
Impairment . . . 43
4. Effect of NOx Emission Rates on Visibility
Impairment 54
D. Power Plant Siting Contraint Flaps 54
V CUMULATIVE IMPACTS OF POWER PLANTS WITHIN A REGION . . . . 64
A. A Generic Regional Model . . . 64
B. Maximum Regional SO 2 Emission Densities and Power
Plant Siting Capacities 68
C. Impact of Maximum S02 Emission Density on Regional
Visual Range 71
VI RECOMflENDATIONS FOR FUTURE WORK . . . 73
APP ENDI CES
A 500 Mwe POWER PLANT IMPACTS . . 78
B 1000 Mwe POWER PLANT IMPACTS . . 95
C 3000 Mwe POWER PLANT IMPACTS . 112
REFERENCES - . . 129
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ILLUSTRATIONS
1 Key to Parameters Used To Characterize Visibility Impairment 22
2 Maximum Ground-Level Air Quality Impacts . 26
3 Estimated Minimum Separation Distances Between Coal-Fired
Power Plants and Class I Areas 32
4 Minimum Separation Distances Between Coal-Fired Power Plants
and Elevated Terrain in PSD Class II Areas Based on EPA
Valley Model Calculations 34
5 Minimum Separation Distances Between Coal-Fired Power Plants
and Elevated Terrain in PSD Class III Areas Based on EPA
Valley Model Calculations 35
6 Effect of S02 Emission Rates on SO Fluxes and
Concentrations Downwind of a 2000 Mwe Coal-Fired
Power Plant 38
7 Effect of NO Emission Rates on NOx Fluxes and
Concentrations Downwind of a 2000 Mwe Coal-Fired
Power Plant . . . 44
8 Effect of SO Emission Rates on Calculated Visibility
Impairment Dgwnwind of a 2000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range . . . 48
9 Effect of NO Emission Rates on Calculated Visibility
Impairment Downwind of a 2000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range . . . 55
10 Mandatory Class I Areas . . 60
11 Power Plant Siting Exclusion Areas Potentially Necessary
To Protect Visibility and To Prevent Significant Deterioration
of Air Quality in Mandatory Class I Federal Areas 61
12 Conceptual Basis for Regional Siting Capacity Calculations . . 65
13 Example of an Isopleth Map Showing Areas Around a Hypothetical
Power Plant in Which Its Air Quality Impact (e.g., SO
Concentration or Plume Perceptibility) Is Greater Than
a Given Value 76
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A-i Effect of SO2 Emission Rates on SOx Fluxes and Concentrations
Downwind of a 500 Mwe Coal-Fired Power Plant 79
A-2 Effect of NOx Emission Rates on NOx Fluxes and Concentrations
Downwind of a 500 Mwe Coal-Fired Power Plant 83
A-3 Effect of SO 2 Emission Rate on Calculated Visibility
Impairment Downwind of a 500 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 87
A-4 Effect of NOx Emission Rate on Calculated Visibility
Impairment Downwind of a 500 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 91
B—i Effect of 502 Emission Rates on SOx Fluxes and Concentrations
Downwind of a 1000 Mwe Coal—Fired Power Plant 96
B-2 Effect of NO Emission Rates on NOx Fluxes and Concentrations
Downwind of a 1000 Mwe Coal-Fired Power Plant . 100
B-3 Effect of SO 2 Emission Rate on Calculated Visibility
Impairment Downwind of a 1000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 104
B-4 Effect of NOx Emission Rate on Calculated Visibility
Impairment Downwind of a 1000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 108
C-i Effect of SO2 Emission Rates on S0> Fluxes and Concentrations
Downwind of a 3000 Mwe Coal-Fired Power Plant . . . . 113
C-2 Effect of NOx Emission Rates on NOx Fluxes and Concentrations
Downwind of a 3000 Mwe Coal-Fired Power Plant 117
C-3 Effect of S02 Emission Rate on Calculated Visibility
rmpairment Downwind of a 3000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 121
C-4 Effect of NO Emission Rate on Calculated Visibility
Impairment Downwind of a 3000 Mwe Coal-Fired Power Plant
Assuming a Typical Western Background Visual Range 125
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TABLES
1 Summary of Typical U.S. Coals and Resulting SO 2 Emissions . . . . 13
2 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class I Areas (Low Terrain) Necessary
To Meet the Class I 3-Hour-Average SO 2 PSD Increment . . 27
3 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class II Areas (High Terrain) Necessary
To Meet the Class II 3-Hour-Average SO 2 PSD Increment . . 27
4 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class II Areas (Low Terrain) Necessary
To Meet the Class II 3-Hour—Average SO2 PSD Increment 28
5 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class III Areas (High Terrain) Necessary
To Meet the Class III 3-Hour-Average S02 PSD Increment 28
6 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class I Areas (Low Terrain) Necessary
To Meet the Class I 24-Hour-Average SO2 PSD Increment 29
7 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class II Areas (High Terrain) Necessary
To Meet the Class II 24-Hour-Average SO 2 PSD Increment. . 29
8 Minimum Separation Distances (km) Between Coal—Fired
Power Plants and Class II Areas (Low Terrain) Necessary
To Meet the Class II 24-Hour-Average SO 2 PSD Increment. . 30
9 Minimum Separation Distances (km) Between Coal-Fired
Power Plants and Class III Areas (High Terrain) Necessary
To Meet the Class III 24-Hour-Average SO 2 PSD Increment . . 30
10 Regional Average S02 Emission Rates and f 1aximum Power
Plant Siting Capacities 70
11 Maximum Power Plant Siting Capacities in the Contiguous
United States 71
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I INTRODUCTION
On 19 September 1978, the Environmental Protection Agency (EPA) pub-
lished in the Federal Register proposed standards of performance for new
electric utility steam generating units (power plants) to revise current
emission standards. In addition to making the standards for nitrogen oxide
and particulate emissions more stringent, the proposed standards would
require that uncontrolled 502 emissions be reduced by 85 percent. The intent
of these proposed regulations is to require new power plants “to use the
best demonstrated systems of continuous emission reduction,” namely, flue
gas desulfurization (SO 2 scrubbers).
In proposing these regulations, the EPA has stated ( Federal Register ,
l978a, p. 42154):
The principal issue associated with this [ emission stan-
dard] proposal is whether electric utility steam gener-
ating units firing low-sulfur-content coal should be
required to achieve the same percentage reduction in
potential S02 emissions as those burning higher sulfur
content coal. Resolving this question of full versus
partial control is difficult because of the significant
environmental, energy, and economic implications asso-
ciated with each alternative [ emission standard].
In November 1978, the EPA’s Office of Planning and Evaluation contracted
with Systems Applications, Incorporated (SAl) to study the air quality and
visibility implications of alternative New Source Performance Standards (NSPS)
for SO 2 . This report describes that study and the conclusions reached re-
garding the impacts on air quality, visual range, and atmospheric discolora-
tion and the constraints on power plant siting resulting from alternate SO 2
emission control requirements.
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We studied three alternate SO 2 emission floors (i.e., maximum required
control levels): 0.2, 0.5, and 0.8 pounds of SO per million Btu heat input
(lb/iD Btu). In addition, we investigated the emission ceiling for coal
(or lignite) of 1.2 lb/b 6 Btu.
In this study, we attempted to answer the following questions:
> What will be the air quality impacts associated with new
power plants meeting alternate emission standards?
> Will these impacts cause exceedances of Prevention of Signif-
icant Deterioration (PSD) Regulations?
> What will be the impact of alternate emission regulations on
visibility impairment (including reductions in visual range
and atmospheric discoloration)?
> What are the implications of alternate SO 2 emission regula-
tions on power plant siting?
> What is the maximum regional power plant siting capacity?
> How close can a power plant be sited to a Class I (pristine)
area without causing significant visibility impairment or
exceedances of PSD increments?
> How close can a power plant be sited to elevated terrain
without causing violations of PSD Class I, II, or III incre-
ments or National Ambient Air Quality Standards (NAAQS)?
> What are the implications for power plant siting in the
regions of the western United States where the terrain is
complex and the number of Class I areas is large?
Chapter II of this report suninarizes the conclusions of our study.
Chapter III outlines the basis for our air quality and visibility calcula-
tions. Chapter IV describes the impacts of individual power plants, and
Chapter V outlines estimated cumulative regional impacts resulting from
regional power plant development. In conclusion, Chapter VI presents
reconi endations for future studies.
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II SUMMARY AND CONCLUSIONS
We have analyzed the impact of various sizes of power plants, which
emit SO 2 and NO at various rates, using EPA-recommended air quality models
and SAl models to estimate air quality impacts and visibility impairment
caused by power plant plumes over the long range (> 100 km downwind) and on
a regional scale. On the basis of these analyses, we have drawn tentative
conclusions of profound significance to air quality planning in the following
areas:
Air quality impacts caused by individual power plants.
Visibility impairment.
> Constraints on power plant siting.
> Cumulative regional impacts.
> Implications for emission control.
> Needs for further research.
Each of these is discussed below.
A. AIR QUALITY IMPACTS CAUSED BY INDIVIDUAL POWER PLANTS
Our conclusions about the air quality impacts of individual power plants
are as follows:
> The Prevention of Significant Deterioration Regulations,
which limit increases in 3-hour- and 24-hour-average SO 2
concentrations, impose the most restrictive limitations
on power plant emissions and siting.
> Maximum 3-hour- and 24-hour-average SO 2 Class I area in-
crements will restrict the siting of and SO 2 emissions
from coal-fired power plants located in Class II areas
as far as 100 to 200 km away from Class I areas.
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> Limited mixing conditions, during which vertical mixing
of emissions is restricted by stable layers 500 to 1000 m
above the ground, are likely to be associated with the
highest 3—hour— and 24—hour—average S02 ground-level concen-
trations; however, in complex terrain areas even higher
ground—level concentrations are likely to occur as a result
of plume impingement on elevated terrain.
> Surface deposition of SO 2 and conversion of SO 2 to sulfate
must be considered in models that are designed to calculate
impacts beyond 100 km from a power plant. More than half•
of the initially emitted SO 2 will be lost by surface depo-
sition at distances greater than 200 km during light-wind,
limited mixing conditions.
> The wind speed that maximizes the impact of power plant emis-
sions on ground—level SO 2 concentrations increases linearly
with the downwind distance of the receptor of concern. Thus,
maximum concentrations at 100 km downwind are likely to occur
with light winds (1 to 2 m/sec), whereas those at 200 to 500
km are likely to occur with moderate winds (3 to 6 in/sec).
flaximum ground-level surface concentrations are not likely
to occur less than 100 km downwind; however, plume center-
line concentrations of sulfate are likely to remain relatively
constant with downwind distance since plume dilution is
counterbalanced by additional sulfate formation.
> Sulfate mass fluxes tend to increase monotonically with
downwind distance, whereas NO 2 fluxes appear to reach maxima
between 20 and 100 km downwind of the power plant, depending
on atmospheric stability.
> The fraction of initial SO, or NO emissions that has been
deposited by the time a plume parcel is transported to a
given downwind distance depends on the travel time, the rate
of plume mixing, ground-level concentrations, and the depo-
sition velocity.
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B. VISIBILITY IMPAIRMENT
With regard to visibility impairment caused by power plant emissions,
we have concluded that:
> Reductions in visual range caused by power plant emissions
depend on the SO 2 emission rate and the rate at which
gaseous emissions are converted to aerosol. Assuming a
0.5 percent per hour S0 2 -to-S0 conversion rate and a
typical western U.S. background visual range of 130 km, a
2000 Mwe (megawatts of electric output) power plant, during
worst-case dispersion conditions, will cause maximum visual
range reductions of 11, 28, 40, and 51 percent as a result
of SO 2 emission rates of 0.2, 0.5, 0.8, and 1.2 lb/b 6 Btu,
respectively. The same plant would cause visual range re-
ductions of 2, 4, 7, and 11 percent, respectively, if it
were located in an area with a background visual range of
15 km (a value typical of the eastern United States). These
estimates correspond to maximum ground-level sulfate concen-
trations of 1, 3, 5, and 8 pg/m 3 for SO emission rates of
0.2, 0.5, 0.8, and 1.2 lb/lU , respectively.
> These estimates of maximum visual range reduction are based
on the assumptions of worst-case meteorological conditions,
location of the observer at ground level within the plume
350 km from the power plant, and an observer’s line of sight
along the plume axis. If the observer’s line of sight is
perpendicular to the plume axis, visual range reductions are
smaller: 4, 9, 14, and 21 percent, respectively, for the
case assuming a background visual range of 130 km.
> Visual range reduction during worst-case meteorological con-
ditions is at least a factor of 5 larger than what it would
be during average meteorological conditions (with higher
wind speeds and mixing depths).
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> Yellow-brown plumes are expected to be visible only when
the background visual range is great--for example, in the
nonurban areas of the western United States--and only
during stable, light-wind conditions. Since such wind
conditions are expected to persist for 11 to 17 hours at
a time, yellow-brown plumes could be transported to 100 to
150 km downwind from a coal-fired power plant located in
the western United States.
> During typical well-mixed and ventilated atmospheric
conditions, plumes from power plants meeting the pro-
posed New Source Performance Standards would not be
visible, regardless of the SO 2 emission rate floor.
C. AIR QUALITY CONSTRAINTS ON POWER PLANT SITING
We have reached the following conclusions about air quality constraints
on power plant siting:
> Power plants that are 1000 Mwe or larger emitting 0.8 lb SO /
10 Btu, or 2000 !lwe or larger emitting 0.5 lb SO 2 /lO Btu,
may cause maximum 24-hour-average ground-level SO concentra-
tions in excess of the PSD Class II increment of 91 jig/rn
according to calculations using air quality models recomended
by the EPA.
According to calculations using the EPA’s Valley Model, 2000 Mwe
power plants will have to be sited at least 18 km away from
elevated terrain if SO emissions are well controlled (0.2 lb/
10 Btu) and at least 50 km away if SO emissions are 0.8 lb/
10 Btu in order to meet Class [ I PSD increments. Even small
(500 Mwe), well-controlled (0.2 lb S0 2 /l0 6 Btu) power plants
will have to be sited at least 50 km from elevated terrain
in Class I areas.
> On the basis of calculations using EPA air quality models, power
plants having capacities of 2000 Mwe or larger, even with SO 2
emission rates as low as 0.2 ib/lO Btu, will have to be sited
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at least 100 km from Class I areas to meet the Class I 24-
hour-average SO 2 PSD increment of 5 ug/m 3 . Large power plants
(2000 to 3000 Mwe) that burn high-sulfur coal or that have
only partial SO 2 control (0.8 to 1.2 lb/10 6 Btu) may have to
be sited as far as 200 km from Class I areas.
> In the western United States, which has excellent background
visual range, large coal-fired power plants may have to be
sited at least 100 to 150 km from Class I areas to prevent
the occurrence of yellow-brown haze in scenic areas during
periods of poor atmospheric dispersion.
> Since maximum reductions in visual ranqe occur more than 200 km
downwind of a power plant, the protection of visual range in
Class I areas cannot be achieved practically through constraints
on siting alone.
> From 60 to 90 percent of the land area of the western United
States (the states of and westward of Montana, iyoming, Colorado,
and New Mexico) may have to be excluded as sites for large coal-
fired power plants to prevent significant deterioration of air
quality and visibility in Class I areas.
D. CUMULATIVE REGIONAL IMPACTS
Our conclusions about the cumulative regional impacts of power plant
emissions are:
> As a result of PSD Regulations, it may be necessary to limit
increases in regional SO 2 emission density to 0.08 to 0.11
g/km 2 /sec.
> With the above increases in regional SO 2 emission density,
regional average sulfate concentrations will be increased by
1 or 2 pg/rn 3 , and visual range will be reduced 18 percent in
the western United States and 4 percent in the eastern United
States on worst-case days.
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On typical days with good ventilation, reductions in visual
range will be much less--about 4 percent in the western
United States and 1 percent in the eastern United States.
E. IMPLICATIONS FOR POWER PLANT EMISSION CONTROL
We have concluded that the implications of our findings for power plant
emission control are:
According to calculations using air quality models reconnnended
by the EPA, it may be necessary to limit SO 2 emissions from
power plants to less than 1 kg/sec, or about 100 tons per day,
to meet Class II PSD Standards in level terrain. Even greater
control may be necessary to meet those standards in complex
terrain. This emission rate is the equivalent of about 0.8 lb/
106 Btu for a 1000 Mwe plant and 0.4 lb/b 6 Btu for a 2000 Mwe
plant.
> If SO 2 emissions from power plants located in the western United
States that burn low-sulfur coal are not well controlled (result-
ing in S02 emission rates less than 0.2 lb/lU 6 Btu), then siting
alternatives will be restricted by the required minimum separation
distance between the site and elevated terrain or Class I areas.
This outcome will occur regardless of the SO 2 emission floor that
is selected for New Source Performance Standards.
> With less stringent SO 2 control (increased SO 2 emissions), limi-
tations become more severe on power plant size, power plant
siting relative to elevated terrain and Class I areas, and the
number of power plants that can be built in a region.
> It appears that with any of the anticipated SO emission floors
considered (0.2, 0.5, and 0.8 lb/1O Btu), PSO increments will
not be used up within regions in the eastern United States as a
result of planned power plant development in the next 20 years,
assuming judicious and well-planned siting. However, as noted
above, power plants located in the western United States will
require full SO 2 control, regardless of emission standards, to
meet stringent PSD Class I Regulations.
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> It appears that the siting and SO 2 emission constraints
imposed by effective enforcement of PSD Class I SO 2 incre-
ments may be sufficient to prevent significant visibility
impairment in Class I areas during most atmospheric disper-
sion conditions. However, during limited mixing or stable,
light-wind conditions, visual range may be reduced by as
much as 20 to 50 percent, and yellow-brown haze may be
visible in Class I areas in the western United States as a
result of power plant emissions more than 200 km away. The
meteorological conditions that would cause such impairment
are expected to occur only a few days each year in the western
United States. The incremental impact of power plant emissions
on visibility in the eastern United States will be much smaller
because of the relatively poor background visual range in that
region.
> Control of SO 2 emissions from power plants will reduce impacts
on visual range at locations several hundred kilometers down-
wind but will increase the yellow-brown plume coloration
caused by N0 emissions. Control of NO emissions from power
plants will reduce atmospheric discoloration but will not
significantly reduce impacts on visual range.
> Long term air quality and visibility goals may require both
SO 2 and NO emission control, particularly for large power plants
located in the western United States.
F. RESEARCH NEEDS
From the results of our study, we have determined the following needs
for further research:
Air quality simulation models that provide realistic estimates
of the transport, diffusion, chemical transformation, and
visual effects of power plant emissions at distances more than
50 km downwind must be developed, tested, refined, and validated.
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> The frequency of occurrence and persistence of meteorological
conditions that cause potential exceedances of PSO increments
must be quantified for different regions of the country.
> Cumulative impacts resulting from proposed new sources should
be analyzed in detail. In particular, the impacts of planned
regional energy development in the western United States on
air quality and visibility in scenic Class I areas should be
eva] uated.
> Tentative conclusions based on this short study should be crit-
ically examined in future, more detailed analyses because of
their significant siting and control implications.
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III BASES FOR CALCULATIONS
This chapter outlines the methodology, assumptions, and techniques
used in our study. These bases for calculations can be categorized as
follows:
> Power plant emission conditions.
Air quality and PSD Regulations.
Meteorological scenarios and air quality modeling.
Visibility modeling.
A. EMISSION CONDITIONS
We evaluated air quality and visibility impacts for several sizes of
power plants: 500, 1000, 2000, and 3000 Mwe. The power plants of larger
capacity were assumed to consist of multiple 500 Mwe units, an average
size for new coal-fired boilers. The 3000 Mwe size is believed to be the
largest capacity likely to be installed at a given site. The 1000 Mwe
size is probably representative of a small power station, and the 2000 Mwe
size (consisting of four 500 Mwe boilers) is believed to be most typical
of developments at a single site.
Power plant emission conditions for this study were selected by the
EPA based on the assumption that the power plant would be equipped with SO 2
(wet) scrubbers and stack heights representing “good engineering practice.”
Power plant emission conditions were assumed as follows:
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Variable Value
Stack height 500 ft
Number of stacks per boiler 1
Flue gas tenperature 175°F (scrubbed temperature of 125°F
plus 50°F reheat)
Flue gas flow rate 2540 acfm/Mwe at 175°F (1,270,000
acfm per stack)
Overall power plant heat rate 9000 Btu/kwh (equivalent to a thermal
efficiency of 38%
SO 2 emission rates of 0, 0.2, 0.5, 0.8, and 1.2 pounds per million Btu
and NO emission rates of 0, 0.2, 0.5, 0.6, and 0.8 pounds (as NO 2 ) per
million Btu were evaluated. Although the particulate (fly ash) emission
standard is 0.03 lb/iD 6 Btu, we found that the 20 percent opacity standard
is the most restrictive on the particulate emission rate. (The opacity
requirement limits particulate emissions to 70 percent of 0.03, or 0.02 lb/
i0 6 Btu.)
A simple formula can be used to express the overall mass emission rates
as a function of emission standards and power plant size:
= (E lb/lU 6 Btu) (P Mwe)
x (9000 Btu/kwe-hr) (1000 kwe/Mwe)
x (453.6 glib) (1 hr13600 sec)
= 1.134 (E)(P) (g/sec)
It is instructive to compare the SO emission rates evaluated (0 < E <
1.2 ib/lO Btu) to the rates that would result from the combustion of various
types of coal. Table 1 indicates the sulfur content, heating value, and
resulting uncontrolled and controlled 502 emission rates in pounds per million
Btu for several typical U.S. coals. Note that several low-sulfur coals, after
85 percent SO 2 control, result in emissions of less than 0.2 lb/b 6 Btu; how-
ever, use of a Midwest (Illinois) coal would cause SO emissions to be almost
at the emission ceiling of 1.2 lb/lU Btu. Thus, the various SO 2 emissions
considered in our study could result from the imposition of alternative floors
(0.2, 0,5, and 0.8 lb/b 6 Btu) or from 85 percent control of a high-sulfur
coal, irrespective of the SO 2 floor.
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TABLE 1. SUMMARY OF TYPICAL U.S. COALS AND
RESULTING SO 2 EMISSIONS
Sulfur Heating Emis ion Rate
Content* Value* ib/lO Btu)
Type of Coal ( percent) IBtu/lbm) Uncontrolled 85% Control
Anthracite (Pennsylvania) 0.8 12,880 1.24 0.19
Semi-anthracite (Arkansas) 1.7 13,880 2.45 0.37
Bi timinous
Pensylvania 1.0 14,310 1.40 0.21
Kentucky 2.8 11,680 4.79 0.72
Illinois 3.8 10,810 7.03 1.05
Subbi tumi nous
Wyoming 0.5 9,610 1.04 0.16
Colorado 0.3 8,560 0.70 0.11
Lignite (North Dakota) 0.9 7,000 2.57 0.39
* Source: Ode (1967).
B. AIR QUALITY AND PSD STANDARDS
To evaluate power plant impacts on ambient air quality, we compared
calculated ground-level SO 2 concentrations with the following National
Ambient Air Quality Standards and PSD increments:
SO 2 Concentrations
( ig/m 3 )
Standard 3-Hour Average 24-Hour Average
PSD Class I 25 5
PSD Class II 512 91
PSD Class III 700 182
NAAQS 1300 365
It can easily be shown that for power plants the SO 2 PSD increments and air
quality standards, not those for particulate and NO 2 , are most controlling.
Furthermore, as shown in the next section, the 24-hour-average SO 2 PSD incre-
ments, rather than the 3-hour-average or annual average, are most restrictive
based on EPA-recommended modeling procedures.
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C. METEOROLOGICAL SCENARIOS AND MODELING APPROACHES
In the 19 June 1978 Federal Register , the EPA referenced two documents
that provide guidance on air quality modeling approaches to be used in
evaluating power plant compliance with PSD Regulations (EPA, 1978; Budney,
1977). The EPA recommends Gaussian modeling approaches and various (some-
what conservative) screening techniques to determine whether there is a
possibility of an exceedance of an ambient air quality standard. These
EPA-recommended models were used in this study.
The EPA stated ( Federal Register , 1978b):
EPA’s assessment of the air quality impacts of new
major sources and modifications will be based on EPA’s
uGuidelines on Air Quality Models, OAQPS 1.2-080,
U.S. Environmental Protection Agency, Research Tri-
angle Park, N.C. 27711, April, 1978. This guideline
is incorporated by reference into the regulations.
Sources may request approval from the Administrator
to use air quality dispersion models other than those
noted in the”Guideline. If the Administrator deter-
mines that the model recommended in the “Guideline”
and the model proposed by a source are comparable,
the proposed model may be used.
EPA intends to retain the screening procedures
set forth in “Guidelines for Air Quality Maintenance
Planning and Analysis, Vol. 10 (Revised), Procedures
for Evaluating Air Quality Impact of New Stationary
Sources,” (October 1977, U.S. EPA, Office of Air Quality
Planning and Standards, Research Triangle Park, N.C.
27711). .
[ EPA] intends to limit generally the application
of air quality models to a downwind distance of no more
than 50 kilometers. This is because dispersion para-
meters commonly in use are based on experiments rela-
tively close to sources, and extending these parameters
to long downwind distances results in great uncertainty
as to the accuracy of the model estimates at such
distances. . .
However, since the 1977 Amendments provide special
concern for Class I areas, any reasonably expected
impacts for these areas must be considered irrespective
of the 50 kilometer limitation or the above significance
levels.
14
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In our study, we used modeling approaches outlined in the EPA’s
“Guidelines for Air Quality Maintenance Planning and Analysis, Volume
10” (Budney, 1977). These Gaussian models have the following
formulation:
X = 2 a u exp [ - ( )2] exp [ - 1(H+z )2] + exp [ - i(H z)2] (1)
where
x = pollutant concentration (ug/m 3 ),
Q 0 pollutant emission rate (g/sec),
f = concentration ratio factors of 0.9 and 0.4 for
3- and 24—hour averages, respectively,
= Pasquill—Gifford dispersion coefficients, which are
functions of atmospheric stability and downwind
distance x,
u = wind speed (m/sec),
y = crosswind distance of receptor point from plume
centerline (m),
z = elevation difference between receptor point and
the power plant site (m),
H = effective plume height (m), equal to the stack
height plus plume rise.
Using EPA—recomended plume rise models based on Briggs’ formulation, we
calculated effective plume heights ranging from 300 m for stable, light—
wind or neutral, strong-wind conditions to 640 m for neutral, light-wind
conditions.
One of the worst-case meteorological conditions occurs when plume mixing
is limited by a stable layer at elevation H . In such a situation, the
plume eventually becomes uniformly mixed vertically for 0 < z <
15
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X (27r) 112 GyHm exp [ . ( )2} (2)
Using the EPA guidelines documents, we selected the following meteoro-
logical conditions to analyze worst-case atmospheric dispersion conditions:
> Limited mixing conditions, Pasquill C stability, u 2.5
rn/sec (0 < x < 50 km).
> Limited mixing conditions, Pasquill D stability, u = 7.5
rn/sec (0 < x < 100 km).
> Stable conditions, Pasquill E stability, u = 4 rn/sec
(0 < x < 100 km).
> Plume impingement conditions, Pasquill F stability, u = 2.5
rn/sec. EPA Valley Model (Burt, l977)--appropriate for ele-
vated terrain only (0 < x < 50 krn).
Although the EPA plans “to limit generally the application of air quality
models to a distance of no more than 50 km” ( Federal Register , l978b), the
Volume 10 guidelines document (Budney, 1977) provides guidance for estimating
impacts at distances up to 100 km downwind. We have used these recommended
models in this study. In addition, we found that evaluation of potential air
quality impacts in Class I areas required estimation of the power plant impacts
at distances more than 100 km from a plant site. Therefore, in addition to the
EPA-recommended approaches for downwind distances up to 100 km, we used a model
with the following characteristics to estimate impacts at distances greater
than 100 km:
> Uniform concentration within a sector subtending 11.25°.
> Uniform concentrations in the vertical direction within
the mixed layer (0 < z <
Mixing depth Hm of 1000 m.
> Wind speed Uc so as to maximize the concentration at each
downwind distance (see below).
16
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> Depletion of the initial SO 2 flux Q 0 as a function of
downwind distance (travel time) resulting from sulfate
formation and SO 2 surface deposition.
> SO 2 —to-SO conversion rate k of 0.5 percent per hour.
> SO 2 surface deposition velocity Vd of 1 cm/sec.
EPA—recon.i ended 3—hour- and 24-hour-average concentra-
tion ratio factors f of 0.9 and 0.4, respectively.
This model can be stated mathematically as follows:
- [ k+(v /H ))x/u
fQe d ni
0 (3)
(2 tan 11.25 ) u i-
We can find the wind speed u at each downwind distance that maximizes x
by taking the derivative of x with respect to u at each given downwind dis-
tance, setting the derivative equal to zero, and solving for u as follows:
=0 4
du 1 2
U 2
Thus, at any given distance x, the wind speed Uc that maximizes the concen-
tration is simply:
(k+ )x (5)
Substituting Eq. (5) into Eq. (3) and simplifying, we have:
x = fQ 0 [ (0.535)(k + )x2H ] (6)
17
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Using the selected values for k, Vd and Hm we have the following formula
for estimating power plant impacts at downwind distances x greater than
100 km:
= ) sec/rn when x is in km. (7)
When one evaluates Eq. (5) for the values of parameters selected, he
obtains:
u = (1.14 . 10.2) rn/sec when x is in km.
Thus, maximum concentrations at 200 km are predicted to occur with a wind
speed of 2.3 m/sec; such winds would transport emissions from the power
plant to the receptor location in 24 hours. Also note from Eq. (7) that
concentrations fall off with the square of the distance downwind. This re—
lationship results for two reasons: With increasing downwind distance,
(1) the plume width is assumed to increase linearly, and (2) the pollutant
flux is decreasing owing to surface deposition and conversion to sulfate.
The model used to estimate regional air quality impacts and visual range
reduction due to several power plants sited throughout a region is described
in Chapter IV.
0. VISIBILITY IMPAIRMENT
The impacts of different rates of power plant SO 2 and N0 emissions on
visual range and atmospheric coloration were evaluated using a plume visi-
bility model recently developed for the EPA by SAl (Latimer et al., 1978).
The reader is referred, in particular, to Volumes I and III of that report
for a complete description of the model and the parameters used to charac-
terize visibility. In this section, we briefly describe the four param-
eters that have been used to characterize visibility impairment and the
assumptions made in the model calculations.
18
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1. Parameters That Characterize Visibility Impairment
We used four parameters to characterize visibility impairment caused by
power plant plumes:
Percentage reduction in visual range
> Blue-red ratio
> Plume contrast
tIE.
Each is discussed below.
Visual range is defined as the farthest distance at which a black object
can be perceived against the clear horizon sky. The percentage reduction in
visual range is calculated as follows:
1 - - - x 100 percent
vO/
where r is the visual range for views through the plume center and r 0 is
the visual range without the plume (ambient background visual range). In
most situations, the percentage 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 percentage reduction in visual range is indicative of the
“haziness” of objects observed through the plume. Until it is diffused, the
plume will affect only a few of the observer’s lines of sight; therefore,
calculated visual range reduction pertains only to specific lines of sight
through the plume center (perpendicular to the plume centerline), not to
prevailing visibility. The magnitude of visual range reduction is not neces-
sarily related to the perceptibility of the plume or to atmospheric discolor-
ation. A significant reduction in visual range could occur without a per-
ceptible plume or atmospheric discoloration.
19
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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 (x = 0.4 pm) to that at the
red end (x = 0.7 pm) divided by the same ratio for the background:
R = Ilme(blue)/Iback(blue )
Iplume(red)/Iback(red)
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 gray 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).
Plume contrast is the normalized difference in light intensity of the
plume relative to the background:
1 (0.55 pm) - I (0.55 pm)
p 1 b 055 pm)
Contrast is evaluated at a wavelength A of 0.55 pm, 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 pm is a simple way of characterizing plume
20
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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 (O.55 .im) > 0,
the plume is a brighter white than the horizon, and with C (O.55 urn) 0,
the plume is a darker gray.
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 l’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 E, which is a function of the change in light intensity or
value ( L*) and the change in chromaticity ( x, y). E can be considered
as a distance between two colors in a color space. The color space is
defined such that equal distances (AE) between any two colors correspond to
equally perceived color changes. This suggests that a threshold ( E 0 ) can
be found to determine whether a given color change is perceptible.
Since the CIE could not decide between two different proposed formulae
for E, both were adopted in 1976 as standard means by which color differ-
ences can be specified. These color differences, which are labeled
E(L*U*V*) and E(L*a*b*), are calculated by the plume visibility code.
We have elected to plot E(l*a*b*). E’s greater than 20 indicate a strong
discoloration, SE’s between 5 and 20 represent weak discoloration, and those
less than 5 indicate that 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.
Figure 1 summarizes these qualitative interpretations of the quantita-
tive specifications of visibility impairment. This figure provides a
key to Figures 8 and 9 presented in Chapter III.
2. Assumptions Used in the Model Calculations
Visibility impairment was calculated for ambient conditions typical of
the western United States for the following reasons:
21
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50.0
Location of Observer Downwind of Power Plant (km)
FIGURE 1.
KEY TO PARAMETERS USED TO CHARACTERIZE
VISIBILITY IMPAIRMENT
50.0
I-
40.0
0
I ”
,30.0
20.0
U
4”
I. 10.0
0. (,
1.1
0
4”
jO.9
INCREASED HAZINESS OR REDUCED VISUAL RANGE
1
PLUMES BLUER THAN BACKGROUND SKY
(OR LESS YELLOW-BROWN)
-—.
0.5
o.
PLUMES MORE RED (OR YELLOW-BROWN)
THAN BACKGROUND SKY
I I I 4444% 4 4 L I I Ill
I
:.:
PLUMES BRIGHTER THAN BACKGROUND SkY
I-
UI
4-
2
-
I Ia
2
-J
•- —0.2
—0.3
PLUMES DARKER THAN BACKGROUND SKY
I I I I I II I I I
III
-I
I L .
0
l .c
10.0 -
INCREASING PLUME
(OR
HAZE)
PERCEPTIBILITY
5.0-
,
4 4 I 4 44 11%
4
I
I -
I
0. —
1
2 4 4 10
20 40 50
100
2t
22
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> The greatest atmospheric discoloration was found by previous
studies (Latimer et al., 1978) to occur in the western United
States, where excellent visibility makes plume discoloration
easily observable. Indeed, because of the relatively poor
background visual range in the eastern United States, plume
discoloration would rarely be seen there.
> Calculations of the percentage reduction in visual range caused
by power plant plumes based on an assumed background visual
range typical of the western United States will be valid for the
eastern United States, assuming that all of the plume aerosol
flux is within the visual range of the observer (10 to 30 km)
and that sulfate formation rates and relative humidity are equal.
However, at large downwind distances (>200 km), percentage reduc-
tions in visual range calculated for the western United States
will overestimate impairment in the eastern United States because
some of the plume sulfate will have dispersed beyond the visual
range.
The following conditions were assumed in our visibility calculations:
> The observer looks horizontally across the plume at a.given
downwind distance.
> The sun zenith angle is 45°.
The scattering angle (between direct solar radiation and the
observer’s line of sight) is 90°.
> The observer is located 5 km from the plume centerline.
The background visual range is 130 km.
The background ozone concentration is 40 ppb.
> The S0 2 -to-SO aerosol conversion rate is 0.5 percent per hour.
> The N0 - .to_N0 aerosol conversion rate is 0 percent per hour.
The mixing depth (Hm) is 1000 m (for Pasquill C and D stabilities).
The Pasquill stability categories are C, D, E, and F.
> The surface deposition velocities for gases and aerosols are 1
and 0.1 cm/sec, respectively.
23
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IV IMPACTS OF INDIVIDUAL POWER PLANTS AND THEIR IMPLICATIONS
FOR EMISSION CONTROL AND SITING
This chapter discusses the impacts of individual power plants ranging in
size from 500 to 3000 Mwe on ambient air quality and visibility. The impacts
of alternative SO 2 and N0 emission rates are also described, along with the
implications of PSD Regulations and visibility protection for Class I areas,
particularly those related to power plant siting and SO 2 and NO emission
control.
A. IMPACTS ON GROUND-LEVEL AIR QUALITY
EPA-recomended air quality models and meteorological scenarios were
used to calculate ground—level concentrations as a function of distance
downwind of a power plant. EPA-recommended models for plume impingement
on elevated terrain and for limited-mixing, light-wind conditions in flat
terrain were used for downwind distances 0 < x < 50 km. For distances
O < x < 100 km, EPA-recommended models were used to model ground-level con-
centrations in flat terrain resulting from stable conditions and from
moderate-wind, limited-mixing conditions. These calculations were supple-
mented with long range transport model calculations for distances beyond
100 km downwind. The transport model developed for this study assumes
uniform mixing within a 11.25° sector between ground level and 1000 m
aloft and reductions in SO 2 flux resulting from surface deposition and
sul fate formation.
To make tractable the calculation of both 3-hour- and 24-hour-average
SO concentrations due to emissions from hypothetical power plants of dif-
ferent sizes (Mwe) and SO 2 emission rates (lb/lO Btu), we calculated the
maximum short—term-average (less than 1 hour) SO 2 concentrations Xpeak
normalized by SO 2 emission rate Q 0 . Thus, with this normalized xIQ 0 we
can compute 3-hour or 24-hour concentrations using a simple ratio:
24
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xave = ave/peak Qo(xrk) (8)
Figure 2 shows these short-term-average (x/Q)’s as a function of downwind
distance and meteorological/atmospheric dispersion condition. Note that the
units of x/Q are seconds per cubic meter.
We have provided clear plastic overlays so that the procedure for obtain-
ing the ratios described above can be performed graphically by the reader.
For this task, select the clear plastic overlay corresponding to the averag-
ing period desired (3 or 24 hour), and align the overlay on the x/Q figure
by placing the ax” on the overlay sheet directly on top of the “x” corres-
ponding to the desired power plant size (500, 1000, 2000, or 3000 Mwe) and
$02 emission rate (0.2, 0.5, 0.8, or 1.2 lb/b 6 Btu). Note that these
plastic overlays show the values of the NAAQS and the Class I, II, and III
PSD increments. Thus, the reader can determine the maximum 3-hour- and
24-hour-average SO 2 concentrations resulting from power plants 0 f given SO 2
emissions and can inirtediately find out whether the power plant would be in
compliance with PSD increments and air quality standards.
B. IMPLICATIONS OF PSD AND ALTERNATE S02 EMISSION CONTROLS
ON POWER PLANT SITING
We used the graphical technique described above to determine the mini-
mum separation distances between power plants and different PSO areas neces-
sary to meet the 3-hour- and 24-hour-average SO 2 PSD increments. Tables 2
through 9 display the minimum separation distances for power plants of dif-
ferent sizes with different SO 2 emission rates located in the following
types of areas:
> Class I areas.
> Elevated terrain in Class II areas [ where the EPA Valley
Model (Burt, 1977) is applicable].
> Low terrain in Class ir areas.
> Elevated terrain in Class III areas.
25
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PAGE NOT
AVAILABLE
DIGITALLY
-------
TABLE 2. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL—FIRED POWER PLANTS AND CLASS I AREAS
(LOW TERRAIN) NECESSARY TO MEET THE CLASS
I 3-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
S02 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 13 29 50 100
0.5 40 50 100 100
0.8 50 100 100 130
1.2 100 100 130 160
TABLE 3. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS II AREAS
(HIGH TERRAIN) NECESSARY TO MEET THE CLASS
II 3-HOUR-AVERAGE S02 PSD INCREMENT
Power Plant Size
• • ( Mwe )
SO 2 Emission Rate
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 4 6 10 13
0.5 7 11 19 24
0.8 10 16 26 35
1.2 13 21 35 47
27
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TABLE 4. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS II AREAS
(Low TERRAIN) NECESSARY TO MEET THE CLASS
II 3-HOUR-AVERAGE SO 2 P50 INCREMENT
Power Plant Size
S02 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 0 0 0 0
0.5 0 0 0 0
0.8 0 0 10 16
1.2 0 0 16 26
TABLE 5. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS III AREAS
(HIGH TERRAIN) NECESSARY TO MEET THE CLASS
III 3-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
SO 2 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 3 5 8 10
0.5 6 9 15 20
0.8 8 13 21 28
1.2 10 17 28 37
28
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TABLE 6. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS I AREAS
(LOW TERRAIN) NECESSARY TO MEET THE CLASS
I 24-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
SO 2 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 33 50 100 100
0.5 80 100 120 150
0.8 100 110 160 190
1.2 100 130 190 230
TABLE 7. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS II AREAS
(HIGH TERRAIN) NECESSARY TO MEET THE CLASS
II 24-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
SO 2 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 6 11 18 25
0.5 13 21 36 48
0.8 18 30 50 50
1.2 25 41 50 50
29
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TABLE 8. MINIMUM SEPARATION DISTANCES (km) BETWEEN
COAL—FIRED POWER PLANTS AND CLASS II AREAS
(LOW TERRAIN) NECESSARY TO MEET THE CLASS
II 24-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
S02 Emission Rate ( Mwe)
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 0 0 0 0
0.5 0 0 17 27
0.8 0 13 30 47
1.2 0 21 47 50
TABLE 9. MINIMUM SEPARATION DISTANCES (kr ) BETWEEN
COAL-FIRED POWER PLANTS AND CLASS III AREAS
(HIGH TERRAIN) NECESSARY TO MEET THE CLASS
III 24-HOUR-AVERAGE SO 2 PSD INCREMENT
Power Plant Size
(Mwe)
SO 2 Emission Rate
( lb/b 6 Btu ) 500 1000 2000 3000
0.2 4 6 11 15
0.5 8 13 22 29
0.8 11 19 31 41
1.2 15 25 41 50
30
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Tables 2 through 5 show separation distances necessary to meet the 3-hour—
average SO 2 PSO increment, and Tables 6 through 9 present the separation
distances necessary to meet the 2 4-hour-average SO 2 PSD increment.
As shown by these tables, the 24-hour-average SO 2 PSD increments are
more restrictive than the 3—hour-average increments. For example, Table 8
indicates that a 2000 Mwe plant emitting SO at a rate of 0.5 lb/10 6 Btu
or a 1000 Mwe plant emitting at a rate of 0.8 ib/lO Btu would violate the
24—hour-average SO 2 PSD Class II increment according to the EPA models
under the assumption of a 500 foot stack.
We should point out that the minimum separation distance between any
of the power plants considered and elevated terrain features in Class I
areas is at least 50 km, the farthest downwind distance at which the EPA
Valley Model should be applied. However, Table 6 indicates that, except
for the smallest SO 2 emission rate considered (0.2] W10 6 Btu from a 500 Mwe
plant), the minimum separation distance between a power plant and a Class I
area would be more than 50 km, simply to prevent exceedances of Class I PSO
increments in low-terrain areas.
Figure 3 suniriarizes the implications of Table 6. Note that with
larger SO 2 emission rates resulting from less stringent SO 2 control the
separation distance between a plant site and a Class I area must increase.
For example, Figure 3 indicates that a well-controlled 2000 Mwe plant burn-
ing low-sulfur coal (0.2 lbm/1O 6 Btu) would have to be sited at least
100 km from a Class I area to ensure that 24-hour-average SO 2 PSD Class I
increments were not exceeded (assuming EPA air quality model guidelines
are correct). However, the same plant without controls would have to be
sited almost 200 km from a Class I area. If an SO 2 emission floor of
0.8 lb/b 6 Btu were adopted, the same plant would have to be sited at
least 160 km away from a Class I area.
Another constraint on power plant siting that is particularly signif-
icant in the western United States derives from the relatively high SO 2
31
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FIGURE 3.
ESTIMATED MINIMUM SEPARATION DISTANCES BETWEEN
COAL-FIRED POWER PLANTS AND CLASS I AREAS
200
I
160
E
U
4.-,
9-
SO 2 Emission Rate (lb/b 6 Btu)
1.2
32
-------
concentrations that can occur in elevated terrain areas. As Figure 2 illus-
trates, if there is elevated terrain near the power plant site equal to or
higher than the effective stack height H, the EPA Valley Model calculations
predict significantly higher concentrations than would be predicted in low-
terrain areas. Figures 4 and 5 illustrate the minimum separation distances
between power plants and elevated terrain in Class II and Class III areas,
respectively.
Figure 4 illustrates that a well-controlled 2000 Mwe coal-fired power
plant (0.2 lb/b 6 Btu) would have to be sited 18 km away from elevated ter-
rain in Class II areas. If the same plant were not as well controlled and
its SO 2 emissions were greater than 0.8 lb/b 6 Btu, the plant would have to
be sited more than 50 km from elevated terrain. Since many potential siting
areas in the western United States are located in the vicinity of elevated
terrain, it would be more difficult to find a suitable site for a power
plant emitting more than 0.2 lb/b 6 Btu. The many valleys in Nevada, Utah,
Colorado, Arizona, and New Mexico have widths ranging from 30 to 50 km and
are surrounded by mountains, ridges, or plateaus. With a plant site in the
middle of such a valley, elevated terrain would be 15 to 25 km away. Thus,
on the basis of EPA Valley Model calculations, full SO 2 control may be
required simply to meet PSD Class II increments in complex terrain. Of
course, this does not imply that full SO 2 control, with a 0.2 lb/b 6 Btu
floor, is necessary throughout the country, but it does suggest that full SO 2
control may be needed in the western United States, regardless of the SO 2
emission floor that is selected for the New Source Performance Standards.
In summary, with less stringent SO 2 control, siting constraints become
more severe relative to Class I areas and elevated terrain. Since large
portions of the western United States are near either elevated terrain or
Class I areas, stringent SO 2 control may be necessary, regardless of New
Source Performance Standards, to meet PSD Regulations.
33
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SO 2 Emission Rates (lb/b 6 Btu)
FIGURE 4.
MINI 1UM SEPARATION DISTANCES BETWEEN COAL-FIRED POWER PLANTS
AND ELEVATED TERRAIN IN PSD CLASS II AREAS BASED ON
EPA VALLEY MODEL CALCULATIONS
E
a)
U
0 0.2 0.4 0.6 0.8 1.0
1.2
34
-------
0 0.2 0.4 0.6 0.8 1.0
SO 2 Emission Rate
FIGURE 5.
MINIMUM SEPARATION DISTANCES BETWEEN COAL-FIRED POWER PLANTS
AND ELEVATED TERRAIN IN PSD CLASS III AREAS BASED ON
EPA VALLEY MODEL CALCULATIONS
E
a)
U
(J
•1
(lb/b 6 Btu)
1.2
35
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C. VISIBILITY IMPAIRMENT
We applied SAl’s plume visibility model to calculate not only visual
impacts (reductions in visual range and plume discoloration, contrast, and
perceptibility), but also SO and NO fluxes and concentrations as a func-
tion of downwind distance for a variety of meteorological conditions. We
selected a range of meteorological conditions for analysis to document the
effect of atmospheric stability on:
> Plume centerline SO, and NO concentrations.
> Ground-level SO and NO concentrations.
> The fraction of SO, and NO flux that is deposited on
the ground.
> The fractions of initial SO 2 and NO emissions that are
converted to sulfate and NO 2 .
> Visual range.
> Plume coloration, contrast, and perceptibility.
We selected a light, 2.5 rn/sec (5.6 mph) wind speed as the basis for
the analysis. The impacts during limited-mixing conditions, assuming a 1000 m
mixing depth, were analyzed using Pasquill C and D dispersion coefficients,
which correspond to slightly unstable and neutral atmospheric conditions.
Pasquill D conditions are likely to persist for more than 24 hours, whereas
Pasquill C conditions are likely to persist for only 6 to 12 hours (Budney,
1977). The impacts were also analyzed during stable conditions; Pasquill E
and F dispersion coefficients were selected, with no vertical limit on mix-
ing. Stable conditions will persist for periods ranging from 11 to 17 hours
(Budney, 1977).
A word about the persistence of meteorological conditions is in order
here. We can calculate the travel time necessary for a plume parcel to be
transported a given distance: Assuming a 2.5 rn/sec wind speed, a plume
parcel will travel 216 km in 24 hours. Thus, since Pasquill C conditions
are expected to persist for 6 to 12 hours, we should consider impacts asso-
ciated with these conditions out to distan$es of 50 to 100 km. Similarly,
36
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Pasquill E or F conditions persisting 11 to 17 hours will carry emissions
to distances of 100 to 150 km. Thus, only the Pasquill 0 conditions should
be used to evaluate impacts beyond 100 to 150 km from a power plant for the
assumed 2.5 rn/sec wind speed. As pointed out by Holzworth (1972), in many
regions of the continental United States, limited mixing conditions with
mixing depths ranging from 1000 to 2000 m, persisting for periods of two to
five days without precipitation, occur more than once per year.
1. Effect of SO 2 Emission Rates on SO Fluxes and Concentrations
Figures 6(a) through 6(d) show for Pasquill C, D, E, and F stability
conditions, respectively, the effect of SO 2 emission rates on S0 fluxes
and concentrations as a function of distance downwind from a 2000 Mwe
power plant. (Similar plots for 500, 1000, and 3000 Mwe plants are pre-
sented in Appendices A, B, and C.)
The top plot in each of these figures shows the distribution of sulfur
between SO 2 and sulfate in the atmosphere and the amount deposited on the
ground as a function of downwind distance. From these plots, one can see
that the SO 2 flux at large downwind distances decreases as a result of sulfate
(S0 ) formation and surface deposition. (Note that the S0 and SO 2 fluxes and
the fraction deposited on the ground are represented by the areas above, between,
and below the curves in this plot.) Within 100 km of the power plant, only a
small fraction of the initial SO 2 emissions is converted to sulfate or is
deposited. However, at distances of 200 to 350 km downwind, 15 to 20 per-
cent of the initial sulfur flux (power plant emissions) has been converted
to sulfate, and up to 65 percent has been deposited. Note that surface
deposition is a function of stability because it is linearly proportional to
ground-level concentrations; thus, during the stable Pasquill F conditions
[ Figure 6(d)], surface deposition is negligible because the plume has not
mixed to the ground.
The second and third plots in Figures 6(a) through 6(d) show the short-
term-average centerline and ground-level SO 2 concentrations on log-log plots.
37
-------
- 1. 2 1. 2 —- -__.__
/ 0.8 __________— — 0.8
2 4 6 10 20 40 60 100 200
DØNN IIN0 DISTRNCE U M)
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 rn Mixing Depth
FIGURE 6. EFFECT OF S02 EMISSION RATES ON SO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 2000 Mwe COAL-FIRED POWER PLANT. S02 emission
rates in pounds per million Btu are indicated.
I I • 311
II.24H
.311
•24H
I • 3H
1.2411
.311
.2411
0.2
S 2
ti.)( 0.8
-J
z .
0.6
UU)
0.4
I’ll-
-I —
I —
200
100
50
20
z
uJ J
10
us
50
200
100
, . 50
-L
20
z
‘ I i
10
us
2
100
50
20 —
10 -
S
2
I
38
-------
>< 0.8
-J
ZL&-
0.6
Ia 0.4
0.2 —
o8
I I I I I I II
50
200
100
U,
z
‘U
I-
I .)
II
20
DEP&ISITED
10
5
50
20
10
5
II • 311
II .24 11
1.311
I.24H
I1.3H
II • 2411
I • 311
1.2411
200
u) 100
_j z
50
‘ UI-
I —
z
2
100
50
20
10
5
2
1
1 2 4 6 10 20 40 60 100 200
DØNNMIND DISTANCE (NM)
(b) Pasquill D Stability, 2.5 rn/sec Wind, and 1000 rn Mixing Depth
FIGURE 6 (Continued)
39
-------
- —-
//
II • 3K
11.24K
I • 3K
1.24K
- -—-11.3K
1.2
I I liii
t I
—#--------1
D WNW1N0 DISTANCE (MI)
(c) Pasquill E Stability and 2.5 m,’sec Whd
FIGURE 6 (Continued)
40
S02
>< 0.8 —
-J
zu-
-
“-s 0.4
Lu -
-I—
0.2
o8
— 200
100
50
— 20
c ) 10
I I I I I II
DEPt 3UEj
50
— 200
e 100
50
20
Oe 10
C.)
2
100
50
II
o,2 20
z
10
5
z
2
II • 24K
I • 3K
I • 24K
2
-------
0.8
-J
—c•4 0.6
0.4
lu I—
0.2 —
00
são
200
a.
100
20
I-
jLU
10
5
5o
200
100
_J
50
20
10
C-)
2
100
502
I I I liii
I I I liii I.— ‘___________
1.2 - 1.2 —
- O.e—......._ o.e —
— 4 6 10 20 40 60 100 200
DOWNWIND DISTRNCE (P9 1)
(d) Pasqufil F Stability and 2.5 rn/sec Wir
2
FIGURE 6 (Concluded)
41
II.3H
11.24W
I • 3t$
1.24W
II • 3H
II. 24W
I • 3W
1.24W
I I I I I I Ii
DEPC I TLL
I I I I I I I I ______________________
50
20
10
S
2
1
1
-------
For reference, the Class I and Class II 3-hour- and 24-hour-average SO 2 PSD
increments are indicated by the horizontal lines. These are equivalent
short-term-average standards obtained by dividing the 3-hour- and 24-hour-
average PSD increments by the appropriate average concentration ratio
factors recommended by the EPA (Budney, 1977) of 0.9 for 3-hour-average and
0.4 for 24-hour-average concentrations, respectively:
XPSDaVe
Xp 50 peak = Xave/peak (9)
The centerline concentrations can also be interpreted as a conservative
estimate of maximum ground-level concentrations if plume impingement on ele-
vated terrain were to occur. The ground-level concentrations displayed in
the third plot were calculated assuming level terrain (or constant plume
elevation above ground). From these plots, one can see that maximum center-
line concentrations occur during stable, Pasquill F conditions, whereas
maximum ground-level concentrations occur with unstable, limited-mixing,
Pasquill C conditions at about 10 km downwind. Note that for limited-mixing
conditions (Pasquill C), the plume has become well mixed between the ground
and the stable capping layer at 1000 m , so that at distances beyond 20 km
the centerline and ground-level concentrations are equal. Under Pasquill C
limited-mixing conditions, a 2000 Mwe power plant emitting 0.8 lb S0 2 /l0 6 Btu
would barely meet the Class II 24-hour-average SO PSD increment at 10 km
downwind. Even a well-controlled (0.2 lb/lU Btu) 2000 Mwe plant would have
to be located at least 100 km from a Class I area to meet Class I PSD incre-
ments during both limited-mixing and stable conditions. (See the appendices
for information on 500, 1000, and 3000 Mwe plants.)
The fourth plot in Figures 6(a) through 6(d) shows plume centerline
sulfate (SO ) concentrations assuming a 0.5 percent per hour SO 2 toSO
conversion rate. Note that for all the meteorological conditions investi-
gated the sulfate concentration remains nearly constant with downwind dis-
tance, since sulfate is forming as rapidly as the plume is diluting. Cal-
culated centerline SO concentrations depend on the SO 2 emission rate and
42
-------
the stability. At the 0.2 lb/10 6 Btu emission rate, centerline sulfate
concentrations range from 1 to 15 g/m 3 . For Pasquill C and D, at large
downwind distances, ground-level S0 concentrations will equal centerline
concentrations because emissions are well mixed. Thus, we see that ground-
level sulfate concentrations can be as high as 1, 3, 5, and 8 pg/rn 3 for the
SO 2 emission rates of 0.2, 0.5, 0.8, and 1.2 lb/10 6 Btu, respectively, from
a 2000 Mwe power plant.
2. Effect of NO Emission Rates on NO Fluxes and Concentrations
x V
Figures 7(a) through 7(d) show plots of NO fluxes and concentrations
as a function of NO emission rates of 0.2, 0.5, 0.6, and 0.8 ib/1O Btu.
Note that the NO-to-NO 2 conversion rate, as evidenced by the top plot in
each of these figures, depends on the rate of plume dilution (atmospheric
stability). Figure 7(a) shows the limiting effect of the background ozone
concentration (assumed to be 40 ppb) on ground-level NO 2 concentrations.
Both of these effects occur because the reaction responsible for most of
the NO 2 formation requires background ozone to be mixed into the plume:
NO+0 3 ±NO 2 +0 2 (10)
Plots similar to Figures 7(a) through 7(d) are shown in the appendices
for other power plant sizes (500, 1000, and 3000 Mwe).
3. Effect of SO 2 Emission Rates on Visibility Impairment
Keeping the NO emission rate fixed at 0.6 lb/lU 6 Btu, we evaluated
X 6
the effect of various SO 2 emission rates (0, 0.2, 0.5, 0.8, and 1.2 lb/lU
Btu) on visibility impairment. Figures 8(a) through 8(d) show the calcu-
lated impairment due to a 2000 Mwe power plant for the four meteorological
conditions: Pasquill C and D limited-mixing conditions and Pasquill E and
F stable conditions.
The most striking effect of less stringent SO 2 control (increased $02
emission rates) is the reduction in visual range at distances more than
43
-------
(a) Pasquill C Stab’lity, 2.5 rn/sec Wind, and 1000 m 1ixing Depth
FIGURE 7. EFFECT OF NO EMISSION RATES ON NOx FLUXES AND CONCENTRATIONS
DOWNWIND OF A 2000 Mwe COAL-FIRED POWER PLANT. NOx emissions
rates in pounds per million Btu are indicated.
50
U. A 0.8
-J
0.6
-J—
0.2
00
5O0
— 200
00
‘ 20
p-z
“Li
u 10
us
50
200
100
50
20
10
5
50
— 200
Z 100
.Jz
50
‘ ii-
-‘
20
a 10
U 5
2
B RN0
?ØNE
B&RND
1 2 4 6 10 20 40 60 100 200
D WNNIND DISTANCE (t M)
44
-------
(b) Pasquill D Stability, 2.5 rn/sec Wind, and 1000 ‘ “xing Depth
FIGURE 7 (Continued)
ZLi .
uz
w$-.
0.8
0.6
0.4
0.2
o8
200
I [ 00
50
20
10
S
50
200
100
z 50
20
z
U
10
5
50
2 200
Z 100
50
Iu
U
20
10
B RN0
ZØNE
bPffiU
Z NE
5
2
1 2 4 6 10 20 40 60 100 200
D WNWIND DISTANCE (P M1
45
-------
(c) Pasquill E Stability and 2.5 rn/sec Wind
FIGURE 7 (Continued)
0.8
0.4
iai-
.1
0.2
00
5 150
-200
100
50
20
z
luuJ
iJ 10
U 5
50
200
100
z! 50
20
jILI
(J 10
U 5
50
200
z 10 0
50
20
U
10
B RND
ØZØNE
BDRND
5
2
1 2 4 6 10 20 40 60 100 200
DØHNHIND DISTANCE (NIl)
46
-------
I I I I I I iij I I I liii I
4 6 10 20 40
DØNNI4IND DISTANCE (l H)
(d) Pasquill F Stability and 2.5 rn/sec Wind
FIGURE 7 (Concluded)
60 100
ti.X 0.8
-J
X l i .
0.6
W I.-
0.2
200
100
z 50
1W
U
z
m
U
20
10
S
50
50
200
100
50
20
I-z
l i i
u 10
U 5
—.200
100
50
20
z
10
m
U 5
2
6 RND
ØZØNE
B RND
Z NE
1
2
200
47
-------
60.0
z 50.0
I-
40.0 —
C
0,30.0 —
20.0 —
ILl
ü- 10.0 —
0.0 —
1.1 —
1.0 -
I -
cr0.9 -
0.6 -
0.7 -
-j
0.6 -
0.5 —
0.4 —
0.1 —
h 0 .0 -
a,
I-
z
-
ILl
-j
-
—0.3 —
30.0 —
25.0 —
20.0 -
ILl
I— 15.0
-J
ILl
C
10.0 —
5.0 —
0.0 —
FIGURE 8.
1
I I I I liii
I I I I I I
2
4 6 10 20
DØWNWIND DISTANCE U M1
(a) Pasquill Stability C
40 60 100
2 J
EFFECT OF SO 2 EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 2000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. SO 2 emission rates in pounds
per million Btu are indicated.
48
I I I I I I I __ I I I I I
-------
60.0
o.o
I —
C.,
L U
30.0
20.0
10.0 - . __ .____________________
0.0 ‘
1.1
0.7
0.5 —
0.4 I I I ii iij I __________________
U.’
II
—0.2 —
—0.3 I I I I I , ___________________ ______________
30.0
25.0
20.0
Lu
i—15.0
“a
10.0
5.0 —
00 I I I 11111 i ________________
1 2 4 6 10 20 40 60 100 200
DVWNWIND DISTANCE t M)
(b) Pasquill Stability 0
FIGURE 8 (Continued)
49
-------
60.0
z 50.0
U
0,30.0 ___
20.0
10.0 — I —
0.0 I I I I I I I I I I I I I I I ijO.Ot _ —4———— —
1.1
1.0
0.6
0.5
0.4 I I I I II I I I II IIj I I
0.1
— ... -
- _______ r.
-
—0.3 I I I I I I i ll I I
30.0
25.0
20.0
Ma
—15.0
____
00 I I I I 1111% I I I I 1111 I I
1 2 4 6 10 20 40 60 100 200
D WNWIND DISTANCE t M)
(c) Pasquill Stability E
FIGURE 8 (Continued)
50
-------
60.0
z 50.0
I-
40.0
, 30.0
- 20.0
z
U
LU
- 10.
0.0
1.1
1.0
I-
0.
0.8
0.7
-j
0.6
0.5
0.4
0. 1
I-
0,
- - ________
- -0.2
—0.3
30.0
25.0
20.0
‘U
‘- 15.
LU
10.0
5.0
0.0
—0.0 — 1
II
I I I I I
2 4 6 10 20 40 60 100 21
DØWNWIND DISTANCE (I M)
(d) Pasquill Stability F
FIGURE 8 (Concluded)
51
-------
100 km downwind. As we noted previously, it is appropriate to consider
only the Pasquill 0 meteorological conditions for distances beyond 100 to
150 km. Therefore, from Figure 8(b) we see that at 200 km downwind (approx-
imately one day’s plume travel time) the reduction in visual range is 1, 3,
8, 12, and 18 percent for the SO 2 emission rates of 0, 0.2, 0.5, 0.8, and
1.2 lb/b 6 Btu, respectively. At 350 km downwind, the visual range reduc-
tion is 0, 4, 9, 14, and 21 percent, respectively. These values are based
on the assumptions that the background visual range is 130 km (typical for
nonurban areas of the western United States) and that the observer is view-
ing with a line of sight perpendicular to the plume axis.
Greater reductions in visual range would be detected if the observer
looked along the plume. We used the incremental increases of sulfate con-
centrations in the plume calculated previously of 1, 3, 5, and 8 pg/rn 3 ,
corresponding to SO 2 emission rates of 0.2, 0.5, 0.8, and 1.2 lb/b 6 Btu,
respectively, from a 2000 Mwe power plant to calculate the maximum reduc-
tions in visual range when viewing along the plume. With a background
visual range typical of the western United States (130 km), the visual
range would be reduced 11, 28, 40, and 51 percent, respectively. For a
background visual range typical of the eastern United States (15 km), the
visual range would be reduced 2, 4, 7, and 11 percent, respectively. Thus,
greater incremental impacts will result from the same sulfate fluxes in the
western United States, where the visual range is excellent, than will
occur in the eastern United States.
Visual range reduction will be greater in stable, ribbon-like plumes,
but these plumes affect only a few lines of sight and do not affect prevail-
ing visibility (in many different directions). Visual impacts caused by
stable plumes are better characterized by the appearance of dark, yellow-
brown haze, which can be quantified using blue-red ratios, plume contrast,
and i E.
Thus, if a 2000 Mwe plant located in the western United States burns
low-sulfur coal with 85 percent SO 2 control, a 4 to 11 percent reduction in
52
-------
visual range, during worst—case meteorological conditions, will occur 200
to 400 km downwind. During typical meteorological conditions, this impact
is likely to drop by a factor of 5, producing impacts of 1 to 2 percent.
However, without SO 2 control, sulfate concentrations would cause a 20 to
50 percent reduction in visual range during poor dispersion conditions and
a 5 to 10 percent reduction during typical dispersion conditions.
Another striking observation can be made from Figures 8(a) through 8(d):
Increased SO 2 emissions cause a decrease in plume coloration, contrast, and
perceptibility during stable atmospheric conditions. As shown previously
(Latimer et al., 1978), plume NO 2 is the principal cause of the dark, yellow-
brown discoloration caused by plumes when viewed against a cloudless horizon
sky. Increases in the ratio of sulfate to NO 2 concentration under these view-
ing conditions have the effect of masking the yellow-brown coloration with a
white-gray haze caused by light scattered by sulfate aerosol. Thus, we see
from Figures 8(c) and 8(d) that as SO 2 emission rates increase:
The plume’s yellow-brown coloration is diminished (indi-
cated by blue-red ratios closer to 1).
The plume becomes less dark (indicated by plume contrasts
closer to 0).
The plume becomes less perceptible (indicated by SE’s
closer to 0).
The conditions under which plume discoloration would be observed down-
wind of a power plant were indicated in previous reports (Latimer et al.,
1978, Volume III) and in Figures 8(a) through 8(d). Plume discoloration is
not likely to be visible in areas where the background visual range is rela-
tively poor, such as the eastern United States. Plume discoloration is most
pronounced in areas with good visibility, such as the western United States.
Figures 8(a) through 8(d) indicate that meteorological conditions have a
strong effect on plume discoloration. During well-mixed conditions [ see
Figures 8(a) and (b)], plumes would be barely visible ( E < 10) assuming a
light, 2.5 rn/sec wind but would be invisible ( E < 5) during well-ventilated
conditions with deeper mixed layers and stronger winds than those assumed here.
However, during stable, light-wind conditions [ as evidenced by Figures 8(c)
53
-------
and 8(d)], yellow-brown plumes (10 < E < 25) would be visible as far as
100 to 150 km downwind (assuming that stable, light-wind conditions persist
long enough).
As noted previously, SO 2 emission control will increase yellow-brown
plume coloration, not reduce it. As we show in the next section, NO con-
trol is necessary to ameliorate plume discoloration.
4. Effect of N0 Emission Rates on Visibility Impairment
Figures 9(a) through 9(d) show the effect of various NO emission rates
6 X
of 0, 0.2, 0.5, 0.6, and 0.8 lb/lO Btu on visibility impairment assuming a
fixed SO 2 emission rate of 0.5 lb/10 6 Btu. These figures show the effects
for a 2000 Mwe power plant; impairment calculations for 500, 1000, and 3000
Mwe power plants are shown in the figures in the appendices.
Varying the NOx emission rate has a negligible effect on visual range
because it is assumed that nitrate aerosol is not formed. (This assumption
should be checked in future plume measurement programs.) However, the N0
emission rate has a strong effect on plume discoloration. On the basis of
Figures 9(c) and 9(d), plume discoloration could be virtually eliminated
with efficient NO control by reducing NO emission rates to less than
0.2 lb/b 6 Btu.
0. POWER PLANT SITING CONSTRAINT MAPS
We have identified three significant constraints on power plant siting
related to air quality:
> Exceedances of PSD increments in elevated terrain areas
due to excessive 3-hour- and 24-hour-average SO 2 concen-
trations resulting from plume impingement.
> Exceedances of PSD increments in Class I areas due to
excessive 3-hour- and 24-hour-average SO 2 concentrations
during limited-mixing conditions.
54
-------
60.0
z 50.0
I-
U
0
30.0
20.0
U
l i i
* 10.0
0.0
i 1
I I I 1 . . ... .L. I I I II
I I
I I I I IIj I I I I liii
I I
1.1
1.0
I-
0.9
o.e
0.7
0.6
0.5
0.4
0. 1
—0.0
-0. 1
-0.2
—0.3
30.0
I-
0 )
I-
z
U
I
A.
I L l
.- 15.0
ILl
0
10.0 —
5.0 —
25.0 -
20.0 -
0.0
1
FIGURE 9.
— —4— - I I 11111 ‘ ‘ I_L_.I Ill •flfl .—t- -——
2 4 6 10 20 40 60 100 200
0 I4NWIND DISTANCE (tIM)
(a) Pasquill Stability C
EFFECT OF NOx EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 2000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. NOx emissions rates in pounds
per million Btu are indicated.
55
-------
60.0
z 50.0 —
p .-
40.0 -
Li
cr’ 40.0 —
20.0 —
. 10.0 -
0.0 I liii I I I I II iI I
1.1
1.0 _______
::: -_______________
0.6 -
05
04 I I I I I I I I I I I I I I _ I
0.1 - -
I - - — - -
-
Li
-J
-
—0.3 I I i i t __________________ ___________________________________ ______________
30.0
25.0 —
20.0 —
i— 15.0 —
.1
Li
10.0 — __ — -- - 0.8
0.2
0 0 —I----- t I I 4 1 i
1 2 4 6 tO 20 40 60 100
DØWNHIND DISTANCE
(b) Pasquill Stability 0
FIGURE 9 (Continued)
56
-------
I I I I I I
o.o —...L_... 0 0—
- -----0.8
I I I till
I I I liii
i=:: :, ._
1 2 4 6 10 20 40 60 100 20’)
D NNWIND DISTRNCE ( M l)
(c) Pasquill Stability E
FIGURE 9 (Continued)
z
I-
C-)
0,
1-4
z
( —)
ILl
I I I I I Ill
63.0
50.0 —
40.0
30.0 —
20.0 —
10.0 —
0.0
1.1
1.0
I—
0.9
0.8
0.7
-j
0.6
0.5
0.4
0. 1
—0.0
—0. 1
I —
‘I,
I-
C-)
ILl
z
-J
A -0.2
—0.3
30.0
25.0
20.0
Lu
- 15.0
-j
Lu
10.0
5.0
0.0
57
-------
0.0
1.1
1.0
I-
0.9
0.8
0.7
0.6
0.5
0.4
0. 1
- 0.0 ————- —-— -———•——-4 .-.— . 0—
— -0.2—-——-—............ . 0.2—
0 .5 == FB
e
o. 2:•Q
.2
TTTT
1
2 4 6 10 20 40
DØWNWIND DISTANCE (I%MI
(d) Pasquill Stability F
FIGURE 9 (Concluded)
60 100
200
60.0
z 50.0
I - .
C-)
‘U
30.0
20.0
C-)
‘U
o - 10.0
I-
U,
I-
z
C-)
U i
-J
A.
I d
I -
-J
Ui
C
—0.3
30.0
25.0
20.0
15.0
10.0
5.0
0.0
58
-------
Impairment of visibility in Class I areas caused by
increases in haziness due to S0 emissions and the
appearance of dark yellow or brown haze from NO
emissions.
The first constraint potentially limits siting alternatives in complex ter-
rain; the others limit siting near Class I areas.
Figure 10 shows the locations of mandatory Class I areas in the United
States; many additional areas are expected to be redesignated Class I in
the near future.
The calculations presented in this report suggest that, regardless of
which of the alternate SO 2 emission floors for the New Source Performance
Standards are selected, large coal—fired power plants may have to be sited
at least 100 km, and possibly as far as 200 km, from Class I areas. To
illustrate the profound effect this constraint might have on power plant
siting, we drew exclusion area circles with radii of 100 and 200 km around
mandatory Class I areas in the continental United States, as shown in
Figures 11(a) and 11(b). With 200 km circles, virtually all of the western
United States is affected, but even with the 100 km circles most of the
states of California, Oregon, Idaho, Colorado, Arizona, and New Mexico are
affected. With these Class I area constraints, siting alternatives in the
western United States will be limited principally to eastern Montana and
Wyoming, northern Utah, and Nevada.
These results suggest potentially profound siting constraints in the
western United States, and therefore, they deserve careful scrutiny in
future studies. Furthermore, we emphasize that these results are based on:
Possibly conservative calculations using air quality models
recomen’ded by the EPA.
> Generally conservative, average concentration ratios recom-
mended by the EPA.
59
-------
Mt.
D .’o.’d PoJ..
Xau4sor s
‘ tIo & y .N• d
C.uctw’ oI gQ
IJIe Ropole
Er j.to$ ChUS
Møo Pw n
r ’ @ffi
FIGURE 10. MANDATORY CLASS I AREAS
-------
FIGURE 11. POWER PLANT SITING EXCLUSION AREAS POTENTIALLY NECESSARY TO PROTECT VISIBILITY AND TO
PREVENT SIGNIFICANT DETERIORATION OF AIR QUALITY IN MANDATORY CLASS I FEDERAL AREAS
0 i
-
Scale
(a) Assumption of a 100 km Separation Distance
0 290 490 690 800 km
-------
(b) Assumption of a 200 km Separation Distance
N)
0 200 400 600 800 km
I I I I I
FIGURE 11
(Conci uded)
-------
> Assumptions regarding the persistence of worst-case
meteorological conditions.
These models and assumptions should be evaluated in future work.
63
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V CUMULATIVE IMPACTS OF POWER PLANTS
WITHIN A REGION
Another consideration in evaluating the implications of alternative
New Source Performance Standards for power plants is the maximum number
of power plants that can be sited in a given region without causing
exceedances of PSD increments.
A. A GENERIC REGIONAL MODEL
As a first step in estimating these maximum siting capacities, we
developed a simple regional air quality model that can be used to calcu-
late the cumulative impacts of many power plants. The basic assumption
used in formulating this model is that the distribution of new power plant
sites throughout a region is such that emissions are uniformly mixed
between the ground and an elevated stable layer at some downwind distance.
Under this assumption of distributed emissions sources and uniformly mixed
emissions, we do not have to account for rates of vertical and horizontal
atmospheric dispersion.
Figure 12 illustrates the conceptual basis for the regional siting
capacity calculations. The objective of the calculations is to determine
the concentrations of emissions from several power plants sited through-
out a region having dimensions XR and at a receptor location such as
the shaded vertical plane shown in Figure 12. In these calculations, it
is assumed that concentrations are uniformly mixed between the ground and
the top of the mixed layer, which has a height Hm• Emissions are trans-
ported in this mixed layer by a wind of velocity u. The regional SO 2
concentrations may be increased as a function of the downwind distance x
as a result of emissions from additional sources, or they may be decreased
as a result of surface deposition, precipitation scavenging, and conversion
to sulfate.
64
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FIGURE 12. CONCEPTUAL t3ASIS FOR REGIONAL SITING CAPACITY CALCULATIONS
INDIVIDUAL EMISSIONS SOURCE
(e.g., A POWER PLANT)
0•i
01
FORM CONCENTRATIONS OF
PLANE
x
y
-------
We can calculate the concentration at any given downwind distance x
(or transit time t) using a simple box model formula:
= Q(t ) (11)
UHm
The pollutant flux Q per unit crosswind distance y may be increased
if the air parcel is transported over emissions sources Q 0 or may be
decreased as a result of surface deposition, precipitation scavenging,
and chemical conversion to sulfate. For convenience, we treat the con-
tributions of individual sources Q 0 as distributed sources of emission
density q:
(12)
q 2
xs
where
q = emission density (g/m 2 /sec),
= individual source emission rate (g/sec),
x = average source spacing (m).
Ignoring periods of precipitation, we can write a mass balance for
regional SO 2 mass flux as follows:
dQ=qudt_( _)vdudt_kQdt (13)
where vd = deposition velocity of SO 2 (m/sec) and k = SO 2 to SO rate
constant (per sec). Thus, the resulting equation is:
(14)
The solution to Eq. (14) as a function of air parcel travel time is:
66
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Q(t) = r(i - e_ t) (15)
where k’ = k + (Vd/Hm)•
By combining Eqs. (11) and (15), we obtain:
= qj - e t ) = q(i - e u ) (16)
X k’H k’Hm
Thus, the SO 2 concentration x downwind of a region of emission density q is
directly proportional to q and indirectly proportional to the mixing depth
Hm If the air parcel travel time is large over the region of emission den-
sity q, the resultant SO 2 concentration is simply:
X = k’H (17)
Equation (16) is appropriate for estimating concentrations immediately
downwind of an area with emission density q. However, as previously shown,
new power plants cannot be sited within some particular distance of a
Class I area because of the need to ensure that individual sources do not
violate Class I PSD increments. Consequently, over a distance on the order
of 50 to 200 km, an air parcel will be transported over areas with zero
incremental emission densities q (above levels existing when PSD legisla-
tion was enacted). Thus, SO 2 flux is decreased somewhat by conversion to
sulfate and by surface deposition within these exclusion areas around
Class I areas. Equation (16) can be modified as follows to account for
this effect of exclusion areas around Class I areas:
( —k’TR) —k’T 0
X — - (18)
where T is the air parcel transit time over the area surrounding the Class
I region where power plants cannot be sited and is the transit time over
the region in which emissions sources are located.
67
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Similar equations can be derived for sulfur fluxes Q’ and concentra-
tions ‘ if we ignore surface deposition of sulfate (an appropriate assump-
tion since a negligible amount of sulfate is deposited during periods
without precipitation) and precipitation scavenging (an appropriate assump-
tion only for periods without precipitation). Thus, we have:
1.5 kQ (19)
r i —k’T \ —k’T
- 1.5 kg 1 T 1 R 0 20
X — k’I1 [ R k’ -e e
Note from Eq. (20) that, unlike SO 2 concentrations, sulfate concentrations
continue to increase with transit time over a region unless precipitation
occurs and scavenges the aerosol [ see, for example, the plot of sulfate
flux in Figure 6(a)].
We can use Eq. (16) to estimate the maximum increment in emission
density t q allowed by PSD increments xpSD. The value of q can be used
to calculate the siting capacity in megawatts of coal-fired power plants
in a region of known area.
B. MAXIMUM REGIONAL S02 EMISSION DENSITIES AND POWER PLANT
SITING CAPACITIES
It can be shown that the Class I 24-hour-average SO 2 increment of
5 pg/rn 3 is the most limiting PSD increment for the regional siting capa-
city. A limited-mixing situation with a stable capping layer persisting
over a period’ of three to five days without precipitation appears to be
the meteorological condition most likely to cause exceedances of the 24-
hour SO 2 PSD increment in Class I areas due to regional emissions. Accord-
ing to an analysis by Holzworth (1972), this condition occurs more than
once per year in most areas of the United States. In the East, this con-
dition is associated with mixing depths up to 2000 iii, whereas in the West
the associated mixing depths are less than 1000 m.
68
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With these mixing depths, we calculated the maximum regional emission
densities necessary to meet Class I PSD increments using Eq. (18) modified
as follows:
XPSD k’H
= ( — e_k’TR): hT0 (21)
Maximum emission densities of 0.081 g/km 2 /sec for the western United
States (Hm = 1000 m) and 0.107 g/km 2 /sec for the eastern United States
(H = 2000 m) were computed using Eq. (21) and the following values of
parameters:
XPSD = 5 pg/rn 3 (Class I 24-hour—average SO 2 increment),
k’ = I + (vd/H) ,
k = 0.005 per hour (S0 2 -to-sulfate conversion pseudo-
first-order rate constant),
vd = 1 cm/sec (SO 2 deposition velocity),
TR = 2 days (air parcel travel time over the emissions areas),
T = 5 hours (air parcel travel time over the exclusion area
between the emissions area and the Class I area).
We can translate these maximum SO 2 emission densities into maximum
power plant regional siting capacities in terms of megawatts of coal-fired
generating capacity per square kilometer if we know the SO 2 emission rates.
ICE Incorporated (1978) has calculated average regional SO 2 emission rates
corresponding to each of the alternative NSPS SO 2 emission floors of 0.2,
0.5, and 0.8 lb/b 6 Btu, as well as the current NSPS limit of 1.2 lb/b 6 Btu,
for the eastern and western United States. These emission rates are shown
in Table 10, which also presents the maximum power plant regional -siting
capacities for each of these cases.
Using the results shown in Figure 11(a) and Table 10, we estimated
the maximum power plant siting caoacity in the contiguous United States
69
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from the standpoint of air quality (PSD) considerations. From estimates
of power plant siting constraints imposed by Class I areas, we estimated
that approximately 40 percent of the land area of the western United
States (the states of and westward of Montana, Wyoming, Colorado, and New
Mexico) could be used for power plant siting. That area totals 1.3 million
km In the eastern United States, more than 90 percent of the land area
would be left unrestricted for power plant siting from the standpoint of
Class I area protection. That area totals 3.8 million km 2 . By multiplying
the siting capacities shown in Table 10 by these areas, we determined the
maximum coal-fired power plant capacity that can be installed in the United
States, assuming different NSPS limitations. The results of this calcula-
tion are displayed in Table 11.
TABLE 10. REGIONAL AVERAGE SO 2 EMISSION RATES AND MAXIMUM POWER
PLANT SITING CAPACITIES
NSPS S02 Eastern United States _ Western United States
Emission SO2 Siting SO2 Siting
FloQr Emissions Capacity Emissions Capacit
( lb/lob Btu) ( lb/b 6 Btu) ( Mwe/km ) ( lb/b 6 Btu) ( Mwe/km’ )
0.2 0.42 0.22 0.18 0.40
0.5 0.42 0.22 0.28 0.25
0.8 0.52 0.18 0.48 0.15
1.2 0.96 0.10 0.80 0.09
The maximum power plant siting capacities for each of the proposed
NSPS SO 2 floors are well above the 400 gigawatt electric (Gwe) output of
coal-fired generating capacity that was predicted by ICF Incorporated (1978)
to be installed during the period 1975 to 1995. However, with the current
NSPS limit of 1.2 lb/b 6 Btu, planned capacity additions over the period
1975 to 1995 would use up 80 percent of the estimated U.S. power plant
siting capacity. It appears that any of the floors studied for the proposed
70
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NSPS SO 2 standard will be adequate to ensure that a sufficient number of
coal-fired power plants can be built to meet growing energy needs while
air quality goals are being met. Obvtously, a greater number of power
plants can be built in a given region and more area will be available for
power plant siting with the implementation of more restrictive SO 2 ernis-
sion controls.
TABLE 11. MAXIMUM POWER PLANT SITING CAPACITIES IN THE
CONTIGUOUS UNITED STATES
(giqawatts of electric output*)
NSPS SO 2
Emission Eastern Western
( lb/lU 6 Btu) United States± United States Total
0.2 836 520 1356
0.5 836 325 1161
0.8 684 195 879
1.2 380 117 497
* 1 Gwe = 1000 Mwe.
Maximum regional emissions
= (3.8 x iü6 km 2 )(O.107 g/km 2 /sec) = 39,000 tons per day.
§ Maximum regional S02 emission rate
= (1.3 x 106 km )(O.08l g/km 2 /sec) = 10,000 tons per day.
71
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C. IMPACT OF MAXIMUM SO 2 EMISSION DENSITY ON REGIONAL VISUAL RANGE
We evaluated the impact of the maximum regional SO 2 emission density
calculated in the previous section on regional sulfate concentrations and
the resulting impacts on visibility (visual range) as described below.
Using Eq. (20), we calculated the maximun increase in 24-hour-
average sulfate concentration resulting from the calculated maximum allow-
able incremental increases in regional SO emission density of 0.081 and
0.107 g/km /sec for the western and eastern United States, respectively.
These maximum sulfate increments were calculated to be approximately 1.7
l.ig/m 3 for the western United States and 1.4 jig/rn 3 for the eastern United
States.
Using appropriate values of scattering efficiency (b -to-mass
ratios) for the eastern and western United States [ 0.08 and 0.04 x 1O /m/
(pg/rn 3 ), respectively], we calculated the incremental increases in scat-
tering coefficient corresponding to these increases in sulfate concentration
and the resultant reductions in visual range. Assuming an average background
visual range of 130 and 15 km, respectively, for the western and eastern
United States, these increases in sulfate concentration would cause the fol-
lowing reductions in visual range in Class I areas during worst-case limited-
mixing conditions:
18 percent in the western United States.
> 4 percent in the eastern United States.
During more typical, well-ventilated conditions, visual range would be
reduced about 4 percent in the western United States and 1 percent in the
eastern United States. Thus, it appears that limits to growth in regional
SO 2 emission density imposed by effective enforcement of Class I area PSD
increments will be effective in limiting the reductions in visual range in
Class I areas.
72
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VI RECOMMENDATIONS FOR FUTURE WORK
On the basis of our one-month study, we have concluded that significant
constraints will likely be placed on the siting of coal-fired power plants,
particularly in the western United States, to meet air quality goals. We
believe that this tentative conclusion deserves further, iniiiediate analysis
by testing the assumptions about the frequency of occurrence and persistence
of worst-case meteorological conditions.
The following characteristics of the West will limit power plant siting:
> The large number of federal Class I areas and areas that
are likely to be redesignated Class I, with their associ-
ated stringent regulations on SO 2 concentrations to prevent
significant deterioration.
> The excellent background visual range, which makes plume
discoloration much more noticeable.
> The possibility of plume impingement on elevated terrain,
thereby causing relatively large ground-level concentrations.
This and other studies performed thus far by SAl suggest that atmospheric
discoloration, not reduction in visual range, may be the most significant
visual impact caused by new coal-fired power plants meeting the recently
proposed New Source Performance Standards. If the proposed NSPS limits
are adopted, particulate and SO 2 emissions from new plants will be well
controlled, and their impact on visual range and atmospheric discoloration
can be expected to be insignificant. However, even with the more stringent
NO emissions standards recently proposed, large quantities of NO will still
be emitted from new power plants. Our studies have led us to postulate that
NO 2 is the cause of yellow-brown plume discoloration in power plant plumes
73
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and that this discoloration may be visible during periods of poor atmos-
pheric dispersion more than 100 km downwind from a large coal-fired
power plant.
Until large-scale efficient N0 emissions control technology for the
coal-fired power plants is developed, the visual impact caused by yellow-
brown power plant plumes may become a limiting factor in power plant siting
near Class I areas in the West. It may be necessary to exclude significant
land areas around Class I areas from power plant siting to protect scenic
values and to ensure that PSD SO 2 increments within Class I areas are not
exceeded. The implications of these air quality constraints on power plant
siting could be quite significant, as evidenced by Figures 11(a) and 11(b).
We recomend that a more detailed study be performed to assess the
constraints imposed by PSO and visibility protection goals on power plant
siting throughout the United States using actual upper atmospheric meteoro-
logical data to estimate frequencies of occurrence and persistence of
worst-case dispersion conditions. Since the EPA has not yet promulgated
visibility regulations, the nature of such future regulations is unknown.
However, we have used several quantitative measures of visibility (visual
range and atmospheric discoloration) in our model development that could
become the basis of future regulations and could be used to assess the
impact of power plant emissions on Class I area visibility.
In the proposed study, representative National Weather Service upper
atmospheric data could be used to develop a diffusion climatology for the
West (or the entire country if desirable). Such a diffusion climatology,
along with the application of the SAl plume visibility model for various
power plant sizes and emissions controls, would enable production of iso-
pleth maps showing the spatial extent--relative to a power plant site--of
various impact measures (e.g., SO 2 concentration increments or plume
perceptibility E) and the frequency with which each measure would be
exceeded in an average year. Overlaying these isopleths onto maps indi-
cating the Class I areas would produce a final set of maps indicating
where power plant construction (for each plant design) cannot be allowed.
74
-------
To achieve this objective, the proposed study would need to include
the following tasks:
(1) Obtain upper air meteorological data from represen-
tative National Weather Service rawinsonde stations
in the West (or throughout the United States, if desired).
(2) Produce joint frequency distributions of upper air wind
speed, wind direction, and vertical temperature gradients
(indicative of atmospheric stability) for each of these
upper air stations to represent the diffusion climatology
of each region of the country.
(3) Calculate the plume centerline and ground-level SO 2 con-
centrations and visibility impairment increments as a
function of downwind distance for a variety of power plant
sizes, emissions conditions, and diffusion conditions using
SAl’s plume visibility model.
(4) Produce isopleth maps, using the results of Tasks 2 and 3,
illustrating the spatial and temporal extent of air quality
impacts, including visibility, in the vicinity of a power
plant of a given size (see Figure 13). Each isopleth in
such a map would show, as a function of direction from a
hypothetical power plant site, the distance at which an
air quality or visibility impact would occur with the stated
frequency. For example, Figure 13 illustrates isopleths
showing frequencies of occurrence of 1, 10, and 18 times per
year at which a given air quality parameter is exceeded.
Air quality parameters of interest might be the plume
perceptibility parameter E or SO 2 concentrations (e.g.,
the 3-hour and 24-hour Class I PSO increments). These maps
could be produced for various power plant sizes and emis-
sions conditions. Thus, one would have a map like Figure 13
for each combination of power plant size, emission condition,
air quality parameter, and region that was chosen for evalu-
ation. The value of such maps would be their provision of
75
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ON CE
FIGURE 13.
EXAMPLE OF AN ISOPLETH MAP SHOWING AREAS
AROUND A HYPOTHETICAL POWER PLANT IN WHICH
ITS AIR QUALITY IMPACT (e.g., SO 2 CONCEN—
TRATION OR PLUME PERCEPTIBILITY) IS GREATER
THAN A GIVEN VALUE
10 TIMES
PER YEAR
0
50
100
Spatial Scale (km)
76
-------
information about the magnitude, spatial extent, and
frequency of occurrence of the given air quality impact
in a single figure. Also, these maps could be used as
overlays to identify specific areas that should be
restricted for siting (Task 5).
(5) Produce maps of the United States showing Class I
areas (and regions that may be so redesignated) and the
areas surrounding them where the results of Task 4
indicate that the air quality impact of a power plant
of a given size would be too large (from the standpoint
of either PSD Class I SO 2 increments or visibility).
Such maps, together with appropriate overlays, could be
used by both government and industry to identify air
quality constraints on power plant siting and to direct
future research and regulatory efforts.
77
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APPENDIX A
500 MWE POWER PLANT IMPACTS
78
-------
1 1 7 —i--T71TTTT
2 4 6 10 20 40 60 100 200
OII4NNIND DISTANCE (M I
Pasquill C Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
A-i. EFFECT OF S02 EMISSION RATES ON SO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 500 Mwe COAL-FIRED POWER PLANT. SO 2 emission
rates in pounds per million Btu are indicated.
79
-
0.8
zI-
0.6
i —rn
—0.
0.2
a8
200
rn 100
“ 20
p-z
lulu
U 10
U
50
— 200
v ) 100
50
20
10
U
2
100
;; 50
°‘ 20
z
1o
2
1
11 • 3$
I I.24H
I • 3M
1.24$
11.3$
11.24$
I • 3$
1.24$
______ ________ —-—-—4 —
________ : .i
1
(a)
FIGURE
-------
U-)( 0.8
- ‘ 0 6
(JO,
—0.
liD-
0.2
RaS
. 200
100
50
l J 20
I-
‘ULU
c.) 10
C-)
50
200
Cn 100
-Jz
50
20
10
2
100
50
20 —
10 —
5—
[ I ‘ A___
_____________ • 1.2
2—
0.8
I I I II I AL
1
1 6 10 20 40 60 100 200
OØWMMIND DISTANCE ( M l
(b) Pasquill D Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE A-i (Continued)
80
2 4
S 2
II.3M
11.24 11
I • 311
.2411
I I • 311
Ii . 2411
1.311
1.2411
I I II
-------
0.8 —
6
U-)’
-J
. .mt4 0
LU
-a—
S 2
4
0.2
RaR
200
100
50
I I I I I
V
/
DEPØSITEO
20
10
S
50
II.3H
11.24K
I • 3K
I • 24K
1I.9H
11.24K
1 3K
I • 24K
200
100
50
20
10
5
2
100
50
20
10
S
2
1
1 2 4 6 10 20 40 60 100 200
D NNWIPlD DISTANCE (EN)
( )
Pasquill E Stability and 2.5 rn/sec Wind
FIGURE A-i (Continued)
81
-------
S02
DEPØSITED
1 1 1111
I I I I II
I I
—
12
_______I-
0 WNWIND DISTANCE (tEN)
1
2
(d) Pasquill F Stability and 2 5 rn/sec Wind
FIGURE A-i (Concluded)
200
0•8
-J
0 6
0.4
IW —
0.2
o8
200
100
50
20
I-z
Lu
cj 10
C-,
2
500
200
100
. 1
50
c: 20
z
I&i
10
C-,
2
100
50
5
11.311
11.2411
I • 311
1.2411
II • 311
11.2411
I • 3H
1.2411
20
10
5
2
1
82
-------
200
1O0
50
20
z
c ) 10
C-)
50
— 200
100
50
20
10
U
2
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 rn Mixing Depth
FIGURE A2. EFFECT OF NOx EMISSION RATES ON NO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 500 Mwe COAL-FIRED P WER PLANT. NO emission
rates in pounds per million Btu are indicated.
u -) 0.6
-j
0.6
(_ )
0.2
200
100
50
20
10
C -)
BBRND
PZ NE
BGRN O
1 2 4 6 10 20 40 60 100 200
DØWNI4INO DISTANCE ( IU
83
-------
>< 0.6
z
06
up-s
L X
U.
UJt-
z
0.2
o8
—. 200
100
20
zUJ
10
C-)
50
200
100
50
20
IIJLLj
‘.) 10
C-)
50
—. 200
za 100
-J
50
20
‘ 10
C.)
2
— I I I I I I I
1 2 4 6 10
20
40 60 100 200
D WN 4IND
DISTRNCE
( MI
(b) Pasquill D Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE A-2
(Continued)
BBRND
Z NE
6&RPIO
84
-------
.
I I I I I I I I I
I - I 1 I — i L I
2 4 6 10 20 40 60 100 200
D WNWIND DISIRNCE (P M)
BGRND
ØZØNE
(c) Pasquill E Stability and 2.5 rn/sec t!ind
FIGURE A-2
(Continued)
- I
ZLL .
0.6
oz
0.4
uJI-
0.2
00
5O0
200
100
50
20
z
uJtu
u 10
us
2
500
200
100
50
20
10
5
50
200
B RN0
20
5
2
1
85
-------
I I I I II I III I I
I I I I
4 6 i v
DIWNWINO DISTRNCE ( M1
liii !
60 100
(d) Pasquill F Stability and 2.5 rn/sec Wind
FIGURE A-2 (Concluded)
86
200
B RN0
1 NE
B6RNO
0.6
z i& .
0.6
Ih .
U i ’-
0.2
0.0
500
200
a-
100
50
W 20
I-
Ui
L3 10
2
500
200
100
LIJ 20
UJLU
c .3 10
C-)
2
500
— 200
Z 100
-J
50
20
UJ
10
C-)
2
1
2
-------
60.0 —
50.0 —
I-.
40.0 —
Lu
, 30.0 —
20.0 —
C-)
Lu
10.
0.0 1 I I III
1.1
1.0
I — . —‘ — -‘
0.9
0.8
- J
0.6
0.5
04 I I I I III1J I I I I 1111
0.1
—0.0 — •:_.__
-
Lu
-J
a —0.2 —
—03 I I I I I ______
30:0 —
25.0
20.0 —
L i i
- 15.0 —
-J
Lu
10.0
5.0
0.0 11111 _____
1 2 4 6 10 20 40 60 100 20
OVI4NWINO DISTRNCE (EM)
(a) Pasquill Stability C
FIGURE A-3. EFFECT OF SO 2 EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 500 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. S02 emission rates in pounds
per million Btu are indicated.
87
-------
1.1
t.0
0.9
0.8
-J
= 0.6
0.5
0.4
0. 1
—0.3
30 • 0
2 .0
20.0
15.0
10.0
5.0
0.0
4 6 10 20 40
D WP4WIND DISTANCE (EM)
(b) Pasquill Stability 0
FIGURE A-3 (Continued)
88
60.0
50.0
40.0
I J
30.0
0.0
U
I I I I I —
—
— --- •- ----------
I I I I I I I I t
I I I I I
-0.0 - - .
—0.1 —
—0.2 —
1 I_ I I liii I I
1
I I I I I I I I
2
60 100
20i)
-------
p.-
U i
tl
U i
-J
2 4 6 10 20 40
OVI4NWINO DISTANCE (KH)
60.0
Z 50.0
p .-
40.0
Ui
30.0
-
i r !‘—
I I
0.0
1.1
1.0
0.9
0.6
0.7
0.6
0.5
0.4
0. 1
—0.0
—0.1 —
—0.2 -
—0.3 —
30.0 -
250 -
20.0
15.0
10.0 —
5.0 —
0.0 —
p .-
a,
p.-
z
cJ
Lu
x
-J
Ui
p.-
-J
Lu
! :.fl u
I I I I liii I I_ I I I iij I
1
I I I I I I If
60 100 200
(c) Pasquill Stability E
FIGURE A-3 (Continued)
89
-------
I t 1_ iiiil
I I I I I I II
I I I I I I II
I I I I I I II I I
I I I I I I II
2 4 6 10 20 40
D NNWIN0 DISTANCE (EM)
(d) Pasquill Stability F
FIGURE A-3 (Concluded)
90
60 tOO 2 )
I I —
60.0 —
z 50.0 -
I .-.
-
LU
30.0 —
20.0 —
LU
a - 10.0
0.0 —
1.1
1.o
0.9 —
0.8 -
0.6 —
0.5
0.4 —
0.1 —
_ —0.0
a,
I —
z
C-)
LU
-J
a.. —0.2 -
—0.3 —
30.0 —
25.0 -
20.0 -
LU
I— 15.0 -
-J
LU
10.0 —
5.0 —
0.0
1
-------
60.0 —
z50.O -
40.0 -
L i i
30.0 -
::: :
0.0 I
1.1
1.0 —.________________ _____
0.9
o.e
-J
0.6
0.5
04 I I I I III. I I I I II II I I
. -0.0 y: p -
iii
—0.2 —
—0.3 I I _ _______________
30.0
25.0 -
20.0 -
‘U
I— 15.0 -
-j
‘U
10.0 —
::: ‘ ‘‘I
D WNWIP4D DISTRNCE (tIM)
(a) Pasquill Stability C
FIGURE A-4. EFFECT OF NO EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 500 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. NOx emission rates in pounds
per million Btu are indicated.
91
-------
- .
—
--- a j ni I I
JIIIIi
- —.- _
I I I I I I I I I lull
i i ii uI L,. .._ L
60.0
Z 50.0
I-
40.0
‘U
30.0
i— 20.0
C -,
‘U
o 10.
0.0
1.1
1.0
0.9
0.8
ii0.7
-J
0.6
05
0.4
0. 1
I— —0.0
U•)
-0.1
‘U
-J
a. -0.2
—0.3
30.0
25.0
20.0
LU
- 15.0
-J
‘U
10.0
50
0.0
- - -- == n
1
2
4 6 10 20 40 60 100 2 2
DØWNWIND DISTANCE (P P1)
(b) Pasquill Stability 0
FIGURE A-4 (Continued)
92
-------
60.0
50.0
I—
40.0 -
IAJ
30.0 -
20.0 —
10.0 —
0.0 — I —I- _ _
0.e -
LU.? -
-J
0.6
0.5
0.4 i - I ________________________________
0.1 —
,_ —0. 0 — —
C,, _______________
- - U. — =----
-0.1
L i i
-j
-0.2 -
i , , :
30.0
25.0 —
20.0 —
L*1
p-. 15.0
-J
Lii
10.0 —
5.0 —
0.0 ‘ ‘ i ‘ I e r ‘ ‘ ‘ i ______
1 2 4 6 10 20 40 60 100 2C0
DØWNWIND DISTRPICE ( I41
(c) Pasquill Stability E
FIGURE A-4 (Continued)
93
-------
1.1
I I Ii
I I Iii
60.0
Z 50.0 —
I-
40.0 —
U i
30.0 —
0.0
1.0
0.9
l U
0.7
-J
0.6
0.5
0.4
0.1 —
, . —0.0 —
U)
z
-
ILl
-J
-
-0.3 —
90.0 —
25.0 -
20.0 -
‘U
p .-
-J
l&i
I I I I I 1_I
—u •
I I I
15.0 -
10.0 -
5.0 -
0.0
1
2
.. .... —----- .-0. 2— —0. 2 —_. ._
I I — —-----‘-----i i ii an _ i _ r i t , i i - —0.0
4 6 10 20
D6WNWINO DISTANCE (K$)
40 60 100
(d) Pasquill Stability F
200
FIGURE A-4 (Concluded)
94
-------
APPENDIX B
1000 MWE POWER PLANT IMPACTS
95
-------
U-,’ 0.6
-J
ZU-
0.6
(.) Lf)
_J
U. 04
U.”-
-J—
z
0.2
o8
1.311
200
1.2411
50
20
10 .311
(-) 5 1.24 1 1
50
11.311
— 200
100 1 1.2411
50
20
10 1.311
5 12411
2
100
50
20 —
10 —
• 2— 1. 2— . _......
0.8 —‘—--—--._..... ...
, I I I I I I I
1 2 4 6 10 20 40 60 100 200
D WNWIN0 OISTRNCE (P MJ
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE B-i. EFFECT OF SO2 EMISSION RATES ON SO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 1000 Mwe COAL-FIRED POWER PLANT. SO 2 emission
rates in pounds per million Btu are indicated.
96
I.
I I I I I III
0EPø I EJ
5—
-------
2 4 6 10 20 40 60 100 200
OØHNWIND OISTRNCE ( 1cM ’
(b) Pasquill 0 Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE B-l (Continued)
0.8
-J
ZIL-
0 6
3U
0.4
LLJ
-i -I
0.2
a8
200
100
50
20
c., 10
C-)
50
200
100
> 50
20
DZ
10
I I • 3W
I. 241$
.3H
•24H
I • 3W
11 .24K
I • 31$
1.24W
2
100
50
20 —
10 —
5—
2—
It
1
1
.2 1 2
I I I I I I 02- I
I I I I I
97
-------
ta )< 0.8
—3
ZLI.
—c 4 0 6
(_ in
_J
I’-
— 0.4
U i ’-
_J —
0.2
a8
— 200
; 100
50
UJ 20
UJ&u
c.) 10
C.,
50
I I • 311
II • 2411
1.311
200
u,e 100
-iz
50
D 20
z
10
C-,
2
100
1.2411
II • 311
so
20
11. 2411
1.311
.2411
10 —
5
2
1
1 2
-
I . ::. 1.2
- 11/ 8—_____ _____ ___
/ - ------- _i__
- / / 0.2 0.2.
I I I I II II I I I I 1111 __________________
4 6 10 20
D WNWIN0 DISTANCE (tthl
40 60 100
200
(c) Pasquill E Stability and 2.5 rn/sec Wind
FIGURE B-i (Continued)
98
-------
II • 311
11.2411
I • 311
1.2411
II • SN
11.2411
I • 311
1.2411
(d) Pasquill
F Stability and 2.5 rn/sec Wind
FIGURE B-i (Concluded)
0.6
—(S” 0.6
—0.
‘ U I-
_J —
0.2 -
S02
I I I I I I
200
100
50
20
IJJIU
c., 10
V..,
DEP SITEO
f I I _L I I I ______________________________________________
50
200
GA. .
u ; 100
50
(U,-.
20
10
5
2 I I I I I I I I
100
50
20
I I I I
10
5
2
1
1 2 4 6 10 20 40 60 100 200
OØWNNIND DISTANCE (EM)
99
-------
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 rn Mixing Depth
FIGURE B-2.
EFFECT OF NO EMISSION RATES ON NOx FLUXES AND CONCENTRATIONS
DOWNWIND OF 1000 Mwe COAL-FIRED POWER PLANT. NO emission
rates in pounds per million Btu are indicated.
100
u.) 0.8
zu-
0 6
U Z
“ 0.4
lul-
0.2
200
100
50
20
10
5
50
200
! b00
z 50
120
“ 10
( 1
50
8&RNO
1 P4E
I I I I I I
0•
200
Z 100
-Iz
50
20
‘U
10
2
BSRN O
NINE
1 2 4 6 10 20 40 60 100 200
D WPIWIND DISTANCE ( 1
-------
2 4 6 10 20 40 60 100 200
0 NNWIND DISTANCE (I M)
(b) Pasquill 0 Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE 8-2 (Continued)
0.8
-j
x l ’
—“ 0.6
—0.4
0.2
200
100
5o
IaJ 20
lLjl&j
C .) 10
C.)
50
200
100
50
20
10
(-) 5
50
200
100
-j
50
Lu ,—
-.Lc
20
z
tu
10
C.)
S6RND
BSRNO
Z NE
2
1
I I I I IIl
101
-------
Cc) Pasquill E Stability and 2.5 rn/sec Wind
FIGURE B-2 (Continued)
LA .>( 0.8
-J
0 6
C.) Z
0.4
I -.
0.2
o8
200
0
100
20
c ) 10
C.)
2
500
200
100
jjso
20
z
LIJLU
C ) 10
C.)
2
500
—. 200
a .
z? 100
-Jz
50
20
‘ 10
C.)
2
BGRNO
1 NE
8&RN O
ØIINE
1 2
4 6 10 20 40 60 100 200
DØNNWIND DISTRNCE (I NJ
102
-------
I I 1.1 liii I I I liii I
1 2 4 6 10
20
40 60
D WNWIND
OISThNCE
0cM)
N 2
I I I I
0.8
X1a
0.6
I-.
ox
0.4
‘Ii ,-
0.2 —
o8
200
100
‘ 5o
20
10
(-) 5
5o
200
100
50
20
z
C 10
1 )
50
200
xe 100
50
20
10
C-,
2
O. 2
I I I I I II
I I
I I I liii I I
8&RND
BSRND
azeNE
100
(d) Pasquill F Stability and 2.5 rn/sec Wind
FIGURE B—2 (Concluded)
200
103
-------
60.0
z 50.0
I .-
40.0
LU
30.0 —
________ __
0 0 i . - —-‘-------- --- — — 1— rdlT ________
1.1
1.0 _____ ___
0.9 — _________—9 . 09-. I €
0.8
iiO.7
-j
0.6
0.5
0.4 I I 1111 __________
0.1 - ____________________
—0.0—-... _______
L99. .——
-0.1
I ii
-J
- —0.2 —
—0.3 1
30.0 -
25.0
20.0
LU
i— 15.0
-J
LU
10.0
5.0
0.0 I I I I III —
1 2 4 6 10 20 40 60 100
DØWNWIND DISTANCE ( M1
(a) Pasquill Stability C
FIGURE B-3. EFFECT OF S02 EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 1000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. SO2 emission rates in pounds
per million Btu are indicated.
104
-------
60.0
50.0
40.0
30.0
20.0
10.0
z
‘-3
4
z
C.)
‘U
a.
-I
I-
‘U
‘U
-J
I-
U,
I.-.
C.)
U.’
-J
a.
— — ——---- I , _J_______ .%.2_
0.0
1.1
1.0 —
0.9----- ------- ---- ---- -_
0.8 -
0.7 —
0.6 -
0.5 -
0.4 1 I I I lilt
0. 1
—0.0 —
—0.1 —
__________ -
I_ I I I III I
(b) Pasquill Stability D
FIGURE B-3 (Continued)
105
I I I I I III
—0.2
—0.3
30.0
25.0
20.0
‘U
.- 15.0
-J
U.’
10.0
5.0
0.0
I I III
1 2 4 6 10 20 40 60 100 2 ;)
OØWNNIND DISTANCE (NM)
-------
60.0
z 50.0
-
‘U
30.0 —
- 20 0 —
10.0 _______
0.0 - i i i __ .—OU— + -
1.1
1 L0.7 —
-3
—
0.5
0.4 I I I III ________ ______
0.1 -
I-
L
-
U i
- 3
°- —0.2 -
—0.3 I I I I I I I I ________________ _________
30.0 —
25.0
20.0 —
‘ U
I•- . 15.0 —
-j
‘U
10.0 —
5.0-
0 0 I I I I I I I I I I I I I I I I ______________________ = = ._ ____ .I. __
1 2 4 6 10 20 40 60 100 2
DØHNWJND DIST HCE (P M
Cc) Pasquill Stability E
FIGURE 8-3 (Continued)
106
-------
0.9 —
0.8 —
0.7 —
0.6
0.5
0.4
0. 1
—0.0
—0. 1
—0.2
------------------
I I I I I I I I
I I I I I I I
4 6 10 20 40 60 100
OØWNWIND DISTANCE (EM)
I I
(d) Pasquill Stability F
FIGURE B-3 (Concluded)
107
60.0
z 50.0 —
40.0 —
V..)
C
LU
U,
I-
z
LU
0
30.0 —
20.0 —
10.0 —
0.0 —
1.1
1.0 —.
I-
C
LU
I L l
-J
—
I I I I I 1111 I I I I I III I
I-
a,
I-
z
C-)
I i i
-J
—0.3
30.0
25.0 —
20.0 —
LU
— 15.0 —
-J
L i i
C
10.0 —
5.0 —
0.0
1 2
-------
60.0 —
zSO.O —
40.0 —
Lu
,, 30.0 —
20.0 —
A. 10.0 —
0.0 ______________ ________________
0.8
0.7
0.6
0.5
04 — I I II II I I
0.1
-0.0
Lu
-J
—0.2
—0.3 1 I I I I I I I I
30.0
25.0 -
20.0 —
L i i
L ii
10.0
5.0 -
0.0
1 2 4 6 10 20 40 60 100 200
DØWNWINO OISTRNCE (NM)
(a) Pasquill Stability C
FIGURE B-4. EFFECT OF NO EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF 1000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. NOx emission rates in pounds
per million Btu are indicated.
108
-------
60.0 —
50.0 —
L)
a -
‘ Ii
, 30.0 —
20.0 —
CJ
l U
o- 10.0 —
0.0 1 I I I I _____ .OO.2O 1 .t,hJ. u .u 1 _________ _______
i _______________
0.6 -
0.6 -
0.5
8:? I I I I 11(11 _____________________
-0.0
-
iii
—I
—
—0.3 I t I ___________
30.0
250 —
20.0 -
‘U
I-. 15.0 —
-J
L i i
10.0 -
5.0
0.0 — — 1 I • ‘itti fl I i III
1 2 4 6 10 20 40 60 100 21:
D WNWIH0 DISTRNCE (t P1)
(b) Pasquill Stability D
FIGURE B-4 (Continued)
109
-------
I i . . ,__
.
60.0 —
so_U —
40.0 —
30.0 —
20.0 —
10.0 —
0.0
1.1
1.0
0.9
0.8
- 0 . 8
ii-
I 1
0.7 -
0.6
0.5
Lu
z
C-)
Lu
0
I-
l U
LU
-j
C l,
I - .
C-)
Lu
0
Li
-J
Lu
• - - °
______ I I I liii
I I I I
0.4
0.1
—0.0
—0. 1
—0.2
—0.3
30.0
25.0 —
200 —
15.0 —
10.0 —
5.0 —
0.0
1
2
0.
4 6 10 20 10
DØWNWIPID DISTRNCE (P(M
(c) Pasquill Stability E
FIGURE B-4 (Continued)
110
60 100
21 J
-------
40.0 —
30.0 -
20.0 -
10.0
0.0
1.1
1.0
0.9
0.8
0.7
0.6
Oe 5
0.4
0. 1
—0.0
10 0 -
—
5.0
60.0
50.0 —
z
C.)
I&I
U,
I-
z
C-,
‘U
a.
I-
H.
I I I I I iij _____________ _ _I _ __1 I II ii I
-
— 8
I I I I I III I I I I I I I1 I I
I-
U,
I-
z
C-)
I d
-j
a.
‘U
I -
-J
LU
•.. : .••-iI I E: ___ . ..... I ..
-_ _ 0.2
_ l _ I I I III I I I I Illi ____________ —
—0. 1
—0.2 -
-0.3 — ______________________ ____________
30.0 —
25.0 —
20.0 —
15.0 — — — 0.8
0 2—— --—O. 2—-_
I- I III? 9.0 t 1—Il iii
4 6 10 20 40 60 100 200
DØWNNIND DISTANCE (t H
(d) Pasquill Stability F
FIGURE B-4 (Concluded)
111
0.0
1 2
-------
APPENDIX C
3000 MWE POWER PLANT IMPACTS
112
-------
____________________ —1.2 —.—-—_--._.
0. 8— 0.8
______ 5
—i—g•? —
2 4 6 10 20 40 60 100 200
DØWNWINQ DISTANCE (P M)
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 m Plixing Depth
EFFECT OF SO 2 EMISSION RATES ON SO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 3000 Mwe COAL-FIRED POWER PLANT. SO 2 emission
rates in pounds per million Btu are indicated.
113
u-> 0.8
—I
N 0 6
C_) U,
U.
—0.4
UJI-
.1
z
0.2
o8
50
200
Jioo
IiJ 20
z
jLU
u 10
II.3H
24H
.3K
.24K
50
— 200
u) Z 100
-Jz
50
‘U,-
c 20
z
w
10
C.)
2
100
50 —
20 —
10 —
5—
2
1.3K
1.24K
.3K
1
FIGURE C-i.
-------
0.6 -
-J
; LI.
—c •’1 0 6
Q4
I&J
-J—
S 2
0.2
o8
200
100
I I I i 1
EPØSITEO
50
I I I_
20
10
5
50
200
100
50
20
10
5
II.3H
II.2 IH
.3H
.24H
I.3H
1.24 11
311
.2411
2
100
50
20
10
5
2
I
1 2 4 6 10 20 40 60 100 200
O WNWIN0 DISTRNCF 1KM)
(b) Pasquill 0 Stability 1 , 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE C-i
(Continued)
114
-------
0.8 —
1 2 4 6 10 20 40 60 100 200
QØWNHIND DISTANCE (Kill
(c) Pasquill E Stability and 2.5 rn/sec Wind
FIGURE C-i (Continued)
0.6 —
0.4 —
0.2 —
I I I
I I
200
100
I50
20
10
5
50
1.2411
I.24H
— 200
V) 100
50
I c
I-
20
10
5
2
100
50
20
10
11.311
11.2411
1.311
I.2’IH
5
2
1
115
-------
S 2
(d) Pasquill F Stability and 2.5 rn/sec Wind
FIGURE C-i (Concluded)
116
L* ->< 0.8
-J
Z L&
0 6
L) ‘/)
0.4
U i •-
__J —
z —
— 200
100
0.2 —
o8
I I I I liii
I I I I I I
DEPØSITED
I
20
10
5
50
200
o,e 100
50
20
LU
10
1 1.3K
11.24K
1.3K
I.24H
11.3K
11.24K
I • 3K
I • 24K
2
100
50
I I I I I
20
I I I I
10
0 .k
5
2
1
1 2 4 6 10 20 40 60 100 200
DØWNWINO DISTANCE ( MP
-------
0.8
(a) Pasquill C Stability, 2.5 rn/sec Wind, and 1000 m Mixing Depth
FIGURE C2. EFFECT OF NOx EMISSION RATES ON NO FLUXES AND CONCENTRATIONS
DOWNWIND OF A 3000 Mwe COAL-FIRED OWER PLANT. NOx emission
rates in pounds per million Btu are indicated.
0.2
x
Iuz
—I-
C-,
z
C - ,
o8
200
100
50
20
10
5
50
200
100
50
20
10
5
5O
200
100
50
20
10
8 RHD
BZOP4E
8 RNO
ØZONE
S
2
1 2 4 6 10 20
0 WNWIN0 DISTRNCE
40 60 100 200
( M)
117
-------
&i.)( 0.8
-J
ZL&-
-“ 0 6
c_, z
U.,
-J—
0.2
o8
200
10o
50
-&I-
i -. 20
10
c-J 5
50
200
100 ___________
z 50 _________________ ..-. .—--—-——--— 8!RNU
OZONE
f , .- 20
10
C-,
50
200
c J
Z 100
z
!2 50 BGRNO
OZONE
20
z
10
2
(b) Pasquill D Stability, 2.5 rn/sec Wind, and 1000 rn Mixing Depth
FIGURE C-2 (Continued)
118
I I I I I
I I liii I
2 4 6 10 20 40 60 100 200
DØWNWINO DISTANCE (I N)
-------
(c) Pasquil] E Stability and 2.5 rn/sec Wind
FIGURE C-2 (Continued)
119
N02
o8
0.8
-J
0 6
L) Z
0.4
_.I ‘-4
0.2
200
100
50
20
c ’ 10
( .35
P 48
1 1
5O
200
a-
!:100
z! 50
20
( ) 10
C -)
50
200
100
—Jz
50
‘ 20
‘U
10
8&RN0
BZ8NE
B&RNB
OZONE
2
1 2 4 6 10 20 40 60 100 200
DØNNWIND DISTANCE ( M l
-------
Li )( 0.8
-J
‘ 0 6
L) Z
0.4
Lu ,-
-I—
0.2
o8
— 200
100
50
,— 20
10
C-)
50
200
100
! 50
20
( 10
CJ5
50
200
s4
a-
100
z
50
-
20
10
CJ5
2
1 2 4
6
10
20
40 60 100 200
D 4NN1N0 DISTANCE
( (t4)
(d) Pasquill F Stability and 2.5 rn/sec Wind
FIGURE C-2 (Concluded)
8&RN D
Z NE
6 RN0
0ZØ1 E
I i i i i i t i i i i i i I ___________________
120
-------
z 50.0
I-
C.)
L U
0,
z
C .)
l U
o.. 10.0
FIGURE C-3.
_I
I I I ii __
60 100 21
EFFECT OF SO 2 EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 3000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. SO 2 emission rates in pounds
per million Btu are indicated.
121
60.0
40.0 —
30.0 -
20.0 -
-
i —e-— n - — _______
0.0
1.1
1.0
I-
0.9
0.8
0.7
0.6
0.5
0.4
0.1
, . —0.0
05
I-
z
-0.1
LU
-J
°- -0.2
—0.3
30.0
U
I-
1
U i
I I I I LIII I I I 1 1111
- —
I I I I I I I
-.-- -----
I
‘.__L_.........____
25.0 -
20.0 -
15.0 -
10.0 -
5.0 -
0.0
1 2
I I I I I I I I I I I
4 6 10 20 40
D WNWIND DISTANCE (I $1
(a) Pasquill Stability C
-------
60.0
z 50.0
(J
‘ Ii
,,30.0 —
20.0
L __________
i.o
0.7
0.6
05
0.4 I I I II III i i i i hf I _ .. .
0.1
I_—0.0 —
-0.1 - — ..
-
—0.3 I I I I I I I I I I I I I __________________
30.0
25.0
20.0
U i
— 15.0 —
-I
Ui
0.0 - I I I I I I I I I I I I I I I I _________________ ________
1 2 4 6 10 20 40 60 100 2C T
DØWNWIP4D DISTANCE (NM)
(b) Pasquill Stability D
FIGURE C-3 (Continued)
122
-------
60.0
:
-
_
—
—
:_ __ — —F 5 —
iii
z
C.)
0
LU
U)
z
C.)
LU
a-
50.0
40.0
30.0
20.0
10.0
0.0
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0. 1
—0.0
—0.1
0
‘U
¶
L U
-J
U,
p..
2
U
‘U
x
-J
°- -0.2
—0.3
30.0
25.0
20.0
LU
u— 15.0
-J
LU
0
10.0
5.0
0.0
I I I I I
I
I I
1 2 4 6 10 20 40 60 100 2en
0 WN 1ND OISTANCE (t Il)
E
(c) Pasquill Stability
FIGURE C-3 (Continued)
123
-------
60.0
z 50.0
I-
C-,
w
,, 30.0
20.0
Q.. 10.0
0.0
1.1
1.0
I-
0.9
0.6
‘ i0 .7
-j
0.6
0.5
0.4
0. 1
I-
z
C-)
Li
-J
a-
-0.0
—0. 1
—0.2
—0.3
30.0
25.0
20.0
Li
t— 15.0
-J
Li
10.0
5.0
0.0
1 2
4 6 10 20 40 60 100 2::
0 HNWIND DISTANCE (I M)
(d) Pasquill Stability F
FIGURE C-3 (Concluded)
124
-------
60.0
z 50.0 —
I-
C-)
, 30.0 —
20.0 —
C-)
1.1
1.0 — . ..-. .- . .- . t1 ’ ’- U;0 -
0 9 - ‘0 2:L’•OS
-
-
-J
0.6
0.5
0.4 1 I I II _______ , —-- . I I I tIll —
0.1 —
I_—0.0 — . .“ ..
___________ -
1
—0.3 I I I I I I I I i I i i i i I
30.0
25.0
20.0 -
l U
i— 15.0 -
-J
l U
10.0 —
0.0 - - n _ i
1 2 4 6 10 20 40 60 100 20 ’)
DØWNWINO DISTRNCE (EM)
(a) Pasquill Stability C
FIGURE C-4. EFFECT OF NOx EMISSION RATE ON CALCULATED VISIBILITY IMPAIRMENT
DOWNWIND OF A 3000 Mwe COAL-FIRED POWER PLANT ASSUMING A TYPICAL
WESTERN BACKGROUND VISUAL RANGE. NO emission rates in pounds
per million Btu are indicated.
125
-------
60.0 — _________ - 1
z 50.0 —
C-)Ann •
C
,,30.0 —
20.0 -
—
0.0 I - I I _____
1.1
________________________
0 .7
0.6
0.5
0.4 1 I I I I I I I I I I I I I ____________________ _________
0.1
—0.0 — . - - - -.--. . .
___—4---——--——o. 0 — —- —
EEE__t___0 . 2 LJ.
0.1 - _ ____ _.___.. .—U. 6
IJJ
z
-j
-
—0.3 I _________
30.0
25.0 -
20.0 -
15.0 - ‘O B
10 0 - .— -
5.0 - --
0.0 . i , I LU , j 0.0—--j
1 2 4 6 10 20 40 60 100
D I4NWIN0 DI$TRNCE (I M)
(b) Pasquill Stability D
FIGURE C-4 (Continued)
126
-------
it I lit
(c) Pasquill Stability E
FIGURE C-4 (Continued)
127
I I I I I I II
___________________ — —0.0 —4-——o. 0
- 0
II IliiilIItII!IL .
—0.0—
I I I I I I I I
—0.0 ——---———---—--—--o.o
—0.8
I I
I I
___________ 0 . 2
— .------——————----- --- fi 0 — —0.0—-----
I I I 11111 Y. I I I liii _____
1 2
2..
60.h
z 50.0
I-
-, 30.0 —
20.0
w
10.0 —
0.0 —
1.1
1.0
I-
0.9
o.e
ii i 0.7
-J
0.6
0.5
0.4
oil —
I-
a,
-
‘U
x
-J
A —0.2
—0.3 —
30.0 —
25.0 -
20.0 -
-. 15.0 -
-J
U i
10.0 -
5.0 —
0.0
4 6 10 20 40 60 100
D NP4WIN0 DISTANCE ( Pl)
-------
z 50.0
LU
, 30.0
20.0
C-,
LU
0 .
10.0
1.1
0.9
0.8
0.7
0.6
0.5
0.4
0. 1
—0.0 —
:0.0
—0.1 ____ — .-—---—-- ———--————————0.2 0.2 —-
‘013 ________________
30.0 ________________
25.0 -
20.0 -
15.0 -
10.0 — 0.2
5.0 :
__.— .-—- ---—--——---—J.____________ 0 . 0 __________ .________.___—_---1-——o.0
0.0 I I I ii lit I I I II iii I____
2 4 6 10 20 40 60 100 2 O
DØWNWIND DISTANCE (EM)
(d) Pasquill Stability F
FIGURE C-4 (Concluded)
128
60.0
0.0
I I
I -.
IU
LU
-J
— 0 0 • 0
.,
- —,-———---------------———-—-----—— —0 2
. .— .-
- .e 8
I I I III
I-
U,
I —
z
C-)
LU
-j
‘U
-I
LU
C
1
-------
REFERENCES
Budney, L. J. (1977), “Guidelines for Air Quality Maintenance Planning
and Analysis, Volume 10 (Revised): Procedures for Evaluating Air
Quality Impact of New Stationary Sources,’ EPA-450/4-77-OOl, OAQPS
No. l.2-029R, U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, North
Carol i na.
Burt, E. W. (1977), “Valley Model User’s Guide,” EPA-450/2—77-0l8,
U.S. Environmental Protection Agency, Office of Air Quality Plan-
ning and Standards, Research Triangle Park, North Carolina.
EPA (1978), “Guideline on Air Quality Models,” EPA-450/2-78-027, OAQPS
No. 12-080, U.S. Environmental Protection Agency, Office of Air
Quality Planning and Standards, Research Triangle Park, North
Carolina.
Federal Register (l978a), Vol. 43, No. 182, P. 42154, 19 September 1978.
__________ (1978b), Vol. 43, No. 118, p. 26398, 19 June 1978.
Holzworth, G. C. (1972), “Mixing Heights, Wind Speeds, and Potential for
Urban Air Pollution Throughout the Contiguous United State5,” AP-lOl,
U.S. Environmental Protection Agency, Office of Air Progratn ,
Research Triangle Park, North Carolina.
ICF Incorporated (1978), “Further Analysis of Alternative New Source Per-
formance Standards for New Coal-Fired Power Plants,u Pretiminary
Draft, Washington, D.C.
Latimer, 0. A., et al. (1978), “The Development of Mathematical Models
for the Prediction of Anthropogenic Visibility Impairment,”
EPA-450/3-78-.llOa,b,c, Systems Applications, Incorporated, San Rafael,
Cal ifornia.
Ode, W. H. (1967), “Coal,” in Standard Handbook for 1echanica1 Engineers ,
T. Baumeister and L. S. Marks (McGraw-Hill Book Company, New York,
New York), pp. 7-4 to 7-5.
129
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