SHORT-TERM N00 STANDARDS
VOLUME I
SOURCE ASSESSMENT AND
PROBLEM CHARACTERIZATION
DRAFT REPORT
DRAFT
DO NOT MUTE OR CITE
Submitted to:
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Submitted by:
Dale L. Keyes, Bharat Kumar, Robert D. Coleman
and Robert 0. Reid
Energy and Environmental Analysis, Inc.
1111 North 19th Street, 6th Floor
Arlington, Virainia 22209
December 26, 197
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TABLE OF CONTENTS
TITLE . PAGE
PART A: INTRODUCTION . . 1
PART B : GENERAL BACKGROUND 2
1. Emission Sources 2
2. Ambient NO- Formation 3
3. Current Status of N02 Control : 5
PART C: SHORT-TERM N02 10
,1. Point Sources : 10
2. Area Sources 45
3. Alternative Ways to Express the
Short-Term Standard 55
APPENDIX A 57
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STATEMENT
This Draft Report is furnished to the Environmental Protec-
tion Agency by Energy and Environmental Analysis, Inc., Arling-
ton, Virginia. The contents of the report are reproduced herein
as received from the contractor. The opinions, findings, and
conclusions expressed are those of the authors and not necessari-
ly those of the Environmental Protection Agency.
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VOLUME I
SOURCE ASSESSMENT AND PROBLEM
CHARACTERIZATION
A. Introduction
This report is the first volume of a three-volume report
which attempts to identify the conditions leading to high
short-term concentrations of nitrogen dioxide (N0_) and. the types
of sources likely to cause these levels, and to determine the
approximate additional cost of controlling emissions to a
level consistent with attainment of the various ambient air
quality standards under consideration.
This volume deals with the sources of NO emissions, the '
Ji
mechanisms by which nitrogen oxide (NO) is converted to N02
and ambient data on observed NO and N0~ concentrations.
Ji £•
Volume II provides a preliminary assessment of the sources
which, through the mechanisms identified in Volume I, might
cause or contribute to high short-term (i.e., one-hour averaging
period) concentrations of NO-. Once the sources were identified,
control strategies were developed and used to estimate control
costs. Volume III is a detailed case study of the interactive
impact of multiple point and area sources on the short-term
NO- concentrations in the Chicago AQCR. The results of the
case study provide both a basis for the assumptions made in
the nationwide analysis, and a means of gauging the degree of
over- or underestimation of control cost impacts.
The formation of N02 in the atmosphere is a highly complex
process. NO, formed primarily (i.e., 98 percent) as a result of
-1-
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-2-
fuel combustion, can be converted to NO- through oxidation
with either atmospheric oxygen or oxidizing agents such.as
ozone. The degree to which NO is converted to N02 in any
particular location is dependent on many variables.
Since N02 is a largely derived pollutant, some way of
capturing the reaction kinetics had to be devised. The approach
used here is totally empirical. The maximum NO- concentrations
for typical point sources were estimated from NO modelling
a
results and NO -to-NO_ conversion curves derived from actual
*i £•
plume sampling. Alternative approaches have also been pro-
posed. Cole suggests setting maximum NO- equal to the ambient
I/
0, level plus 0.1 times the NOV level. ' This appears to work
j X
well for summer conditions, but should underestimate NO- under
conditions of low 0- concentrations characteristic of winter.
High N02 concentrations associated with area sources are
primarily the result of high NO emission levels and can occur
X
with or without high ozone levels. Emissions from these
sources should be dispersed fairly evenly over a given geographic
area. Data taken from the Washington Metropolitan Area and
other studies appear to support a peak (second highest hour)
to mean (annual average) ratio of 6:1 or less for ambient NO-.
Specific one-hour observations greater than six times the
annual average are believed to represent the influence of
point sources.
B. General Background
1. Emission Sources
By far the most significant source of NO emissions is
Ji
the combustion of fuel. High temperatures and rapid mixing,
which accompany fuel combustion, are conducive to the oxidation
of both atmospheric and fuel-bound nitrogen. The predominant
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-3-
oxidation product is nitrogen oxide (NO), with small amounts of
nitrogen dioxide (N02), and much smaller amounts of other oxides
(N_0-; etc.) also formed. Collectively, these are known as
nitrogen oxides (NO ).
j£
Table 1 summarizes the estimated nationwide NO emissions
J^
in 1976. Of the estimated 23 million metric tons, mobile
sources accounted for 44 percent and stationary source fuel
combustion for 51 percent. The remaining five percent were due
to industrial processes (three percent), solid waste disposal
(0.5 percent), and miscellaneous sources, such as forest fires
(one percent). The mobile source category was dominated by
highway vehicles, primarily autos and small trucks. Stationary
source fuel combustion emissions were divided between electric
utilities (56 percent) and industrial fuel combustion sources,
such as boilers, process heaters, furnaces, and kilns (38 per-
cent) .
2. Ambient N02 Formation
As noted above, nitrogen oxidized during fuel combustion is
emitted primarily as NO. Only about five percent ' of the NO
j±
in the combustion products is in the form of N0_. In general,
the oxidation of NO to NO- in the atmosphere occurs by two
mechanisms: (1) oxidation of NO to N02 in the presence of
atmospheric oxygen, mixed into the plume; and (2) oxidation of
NO to N02 in the presence of oxidizing agents such as ozone,
hydroxyl radicals, or organic peroxy radicals, again introduced
as the plume mixes with the ambient air.
Chemically, the first mechanism is:
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TABLE 1
NATIONWIDE EMISSION ESTIMATES, 1976
(10 metric tons/year)
Source Category NO Percent
x ~~^"""^™~~^~
Transportation 10.1 44
• Highway Vehicles 7.8 34
• Non-Highway Vehicles 2.3 10
Stationary Fuel Combustion 11.8 51
• Electric Utilities 6.6 27
• Industrial 4.5 20
• Residential, Commercial and
Institutional .. 0.7 4
Industrial Processes 0.7 2
Chemicals 0.3 1
Petroleum Refining 0.3 1
Metals 0 0
Mineral Products 0.1 0
Oil & Gas Production and Marketing 0 0
Industrial Organic Solvent Use 0 0
Other Processes 0 0
Solid Waste 0.1 0
Miscellaneous 0.3 1
• Forest Wildfires and Managed Burning 0.2 1
• Agricultural Burning 0 0
• Coal Refuse Burning 0.1 0
• Structural Fires 0 0
• Miscellaneous Organic Solvent Use 0 0
TOTAL 23.0 100
SOURCE: Reference 3.
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In this reaction, the rate of N02 production is proportional to
the square of nitric oxide concentration. Therefore, nitrogen
dioxide production by this mechanism is immediate for NO concen-
trations greater than about 100 ppm and significant 0- concen-
trations. These high concentrations only occur very near the
point of exhaust. As the nitric oxide is diluted to concentra-
tions below 100 ppm, the rate of conversion decreases to a point
where at 1 ppm, the direct reaction with oxygen becomes unim-
portant. It is believed that the conversion of NO to NO-
through this mechanism is limited to roughly ten percent of the
initial NO concentrations. However, for high initial NO con-
a
centrations and high excess air or moderate levels of mixing,
Calvert suggests that this mechanism could result in an initial
A/
ratio of NO, to NO of 25 percent. '
£ *t
Oxidizing agents, such as ozone and hydroxyl radicals,
result in the rapid conversion of NO to NO-. The degree of
conversion, under certain conditions, is directly proportional
to the level of oxidants present. In the absence of photochem-
ical activity, NO- formation due to ozone is on a one-to-one
basis. The same does not seem to be true in the presence of
ultra-violet light accompanied by photochemically reactive
precursors which result in an equilibrium set of reactions
between NO- and ozone.
NO
+ 0- (or other oxidizing agents) »-NO- + 0-
N02 hv -MO+ 0
(hv = ultra-violet light)
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During days when UV radiation levels are high, the afternoon
levels of N02 are set by these competing reactions. The forma-
tion of organic nitrates .from oxygenated hydrocarbon compounds
also serves to diminish the concentration of NO-.
Meteorological conditions also play an important role.
Weather conditions obviously determine the amount of sunlight
available to drive the photochemical reactions. In addition,
mixing depth and wind speed will influence the degree of atmo-
spheric dispersion.
The various factors affecting the formation of ambient NO-
can be narrowed down to:
(1) NO emission levels;
Jt
(2) Meteorological conditions: atmospheric
stability and wind speed;
(3) Ambient levels of ozone, hydroxyl radicals,
and organic peroxy radicals; and
(4) Solar ultra-violet radiation and temperature.
The degree to which the above factors affect the NO- and
NO relationship is discussed in detail under Section C.I.a.
X
3. Current Status of NO- Control
Nitrogen dioxide is one of the original six criteria pollu-
tants for which EPA National Ambient Air Quality Standards were
promulgated in 1971. Based on the health and welfare effects
information available at that time, an annual standard was set
at 100 yg/m (annual average) to protect the population against
the effects of long-term low-level NO- concentrations.
In 1975, only seven AQCR's recorded annual N02 averages
above the annual standard. However, many AQCR's do not have
sufficient data on NO- concentrations to determine a valid
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annual average. Thus, the actual number exceeding the annual
standard could be greater.*
Monitored NO- concentrations for sites with several years
6/
of data do not show consistent trends. ' In the Los Angeles
Basin, the annual average of hourly data and the annual average
of daily one-hour maximum increased from 1971 to 1973 and de-
creased thereafter. In Chicago, NO- concentrations have fluctu-
ated since 1969 and no clear trend is discernible. New Jersey
and Denver NO, concentrations increased except during the fuel
shortage in 1973 and 1974.
Since only a few areas have shown violations of the current
NO- standard, most state implementation plans (SIP) limit NO
ft X
emission regulations for "stationary sources to large utility and
industrial boilers and nitric acid plants.
Most of the emphasis on reducing NO emissions has come
ji
from the Federal motor vehicle control program and the develop-
ment of new source performance standards for selected stationary
sources. Table 2 shows the emission limits imposed by these
programs. Interest in NO emission controls is increasing, and
X>
subsequent sections of this report will detail the available
controls for stationary sources.
Since nitrogen oxide contributes to the formation of ozone
and other oxidants, the control of NO emissions has been used
a
by some states, noticeably California, to reduce levels of
photochemical smog. However, the chemistry of oxidant formation
*0ne recent study ' concluded that there is greater than 50 per-
cent chance that 34 AQCR's would be in nonattainment status if
sufficient data were available.
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Table 2
FEDERAL LIMITATIONS FOR NO
Vehicle Exhaust Emission Standards (non-California)
1. Light-duty vehicles
Model year
1973-76
1977-80
1981+
2. Light-duty trucks
No Emission Standard
3.0 gin/mi.
2.0 gm/mi.
1.0 gm/mi.
a. Vehicle weight less than 6,000 Ibs.
Model year
No Emission Standard
1975-78
*1979-84
*1985+
3.1 gm/mi.
2.3 gm/mi.
1.4 gm/mi.
b. Vehicle weight 6001-8500 Ibs.
Model year
Pre-1979
1979-82
*1983-84
*1985+
3. Heavy-duty gasoline vehicles
Model year
1974-78
1979-84
1985+
4. Heavy-duty diesel vehicles
Model year
1974-78
1979-82
*1983+
No Emission Standard
Same as HDG vehicles
2.3 gm/mi.
2.3 gm/mi.
1.4 gm/mi.
Emission Standard
15.3 gm/mi.
13.3 gm/mi.
5.35 gm/mi
HC plus NO Emission Standard
16 g/bhp-hr.
1.5 g HC and 10g. NO
5gHC plus NO
Same as HDG Vehicles
x
or
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5. Motorcycles
Model year NO Emission Standard
*1985 0.14 g/km
Stationary Source Emission Limits
1. Fossil-fuel fired steam generators
Coal-fired boilers 0.7 Ibs. of NO /lo!j Btu
Oil-fired boilers 0.3 Ibs. of NO;Y10; Btu
Gas-fired boilers 0.2 Ibs. of N0^/10b Btu
2. Gas turbines 0.3 Ibs. of NO^IO6 Btu
3. Nitric acid plants 3 Ibs. of NO /ton of 100% acid
* Predicted standards
Sources: References 8, 9 and 18.
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is not well characterized at the present time, and the effec-
tiveness of such a strategy is open to question. Evidence from
smog chamber experiments indicates that reducing NO emissions
X
may actually increase 0^ concentrations if the initial ratio of
nonmethane hydrocarbons to NO (both measured as ambient con-
centrations) is low. ' Empirical studies in Los Angeles, on
the other hand, indicate that levels of 0, downwind of Los
Angeles are correlated with NO emissions.
C. Short-Term NO,,
This section reviews selected ambient monitoring data
around stationary sources and in the vicinity of area sources.
Diurnal, seasonal, and spatial variations in the NO and NO-
concentrations at these sites are discussed. Finally, the re-
lationship between the NO, and NO levels is further examined.
^ X
1. Point Sources
a. Observed N02 and NO Concentrations
The observations reported in this section are based on
maximum hourly NO and NO- concentrations measured at continuous
monitoring stations around selected American Electric Power
Service Corporation (AEP) plants. ' In addition, continuous
NO data in the vicinity of Potomac Electric Power Company
127
(PEPCO) plants were analyzed. /
Continuous NO data at each of these sites have been col-
lected using the chemiluminescent measuring technique. The
monitoring stations were sited to measure the maximum ground-
level impact of nonreactive emissions from the sources based on
diffusion modelling. Simultaneous NO- measurements were not
made at the PEPCO sites.
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Figure 1 shows the location of AEP plants and the monitor-
ing network around each power plant cluster. Stations where NO-
and NO were measured are marked NO . (The location of these
X X
sites is approximate. Appendix A contains detailed maps of the
plants and the monitoring sites around them.) Figures 2, 3, and
4 show the location of PEPCO plants and the respective NO
monitoring sites. Although the power plant in each of these
areas is the largest source of NO in the immediate area, there
generally are other sources which can contribute to the observed
NO and NO, levels.
X £»
1) Diurnal Variations
Figures 5 through 10 show the diurnal variation in the NO,
N0_, and NO concentrations observed in the vicinity of two AEP
plants for different periods of the year. The values in these
curves are averages for each hour over a period of three months.
It is difficult to generalize the diurnal variations in the
ground-level concentrations of a pollutant on any given day.
But with concentrations for an hour of the day averaged over an
extended period, anomalies are smoothed and the emerging trends
can then be generalized. A pronounced NO bulge in the mid-
morning, significantly higher than that in the evening, can be
seen in almost all these curves. Another interesting observa-
tion is the occurrence of N02 bulges, less pronounced than those
for NO , but again, in the mid-morning and evening hours. Even-
X
ing peaks in this case are slightly higher than the morning
levels. Overall, NO appears to be considerably more variable
than H02.
The highest hourly NO- and NO concentrations at these
sites have been further analyzed to check for any deviation in
their occurrence from the general findings discussed above.
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FIGURE 1
AEP MONITORING SYSTEM
UOHI10IIHO ItATIOMI
flLCPllOMI Llllll
Forl Wayne o
/n d la n a
o Indianapolis
IIKEEI)
ROCKPOR
NO,
.NO.,
o Canton
O/iio
Columbus o
PIIILO
GAVIN
Kff« Creek
IDVIC)
Kentucky
BIQ SANDY
UUSKIHGUM
NOy
Cliarleslon
West
Virgini a
ro
I
SOURCE; American Electric Power Service Company
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FIGOEE 2
NO,, MONITORING SITE LOCATION IN THE DICKERSON AREA,
A '
MARYLAND
LILYPONS
(THOMAS)
BEALLS^
(HUNTER
SOURCE; Potomac Electric Power Company
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FIGORE 3
NO MONITORING SITE LOCATION IN THE MORGANTOWN AREA
2£
(PEPCO) MARYLAND
SHILOH
OULBY
C1NG OROROE
COUNTY
•>r/ /
MOIltiANTOWN
U..S. NAV.M.
tlOVINC; GHOLIND
O'DEE
(LLOYD)
mile
SOURCE; Potomac Electric Power Company
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flGUKE 4
NO MONITORING SITE LOCATION IN THE CHALK POINT AREA -
MARYLAND
. .
Ann Arundel County
Prtnce fieorges County
\!i '
'»\ CHESAPEAKE1 BAY
Calvert County
Lower Marlboro
CTarles County ^f *m
' AQUASGO (Jdv)-'""
X Stoakley
Frederick
4 oi « C
Benedict«l^ERIDAN KT, (WATSON)
* .'f~' \ \
VICINITY OF CHALK POINT
POWER GENERATING STATION
SOURCE: Potomac Electric Power Comoanv
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FIGURE 5
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, N02 AND NOX
CONCENTRATIONS FROM STATIONARY SOURCES
o.oo
GAV!W.KYG£R CREEK.SPQRM
LAKIM C33
C 1 3 S « C 0 T C 8 tO II IS II 1C IV 16 IT 1C 19 IO *t t* »•
KOJ3 & DAY CCTQ8GR !S7S - DSCCHfccR IS76
HOURLY AVERAGE K32 K3 AFO WUX COCEKTRAT1QK CPPHJ
X ••«•
GAVIN.KY6E1? CREEK.
LAKIK
S «•••
| ••-
hJ
§ «•*»
*.«
s
^
--*
mm***
^
^^
**.
"-*
X
NO
1MMM
NO
---'
r..
x
,^^
I
1
A
7
ox
&
\
Sv
**"S
\
immmm
• •
mm^mm
^•VM
— *
— .
•**.
. i*
--^
^•W
— —
/
>
/*
•*s
•«^.
NO:
NO
i
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FIGTIKE 6
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, NO2 AND NOX
CONCENTRATIONS FROM STATIONARY SOURCES
„ GAVIN.KYGER CREEK.SPORN
r o.w LAKIN (33
Q.
Q»
£_ O.O4
U
O o.o»
X
o
O.Oi
a
. < -
O o.o«
(N
2 O.O
I
13 || |4 It |* 17
HOUR OF DAY APRIL 1977 - JUNE 1977
HOURLY AVERAGE N02 NO AND NOX CONCENTRATION CPPM3
NDX
SOURCE: American Electric Power Service Corporation
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FIGORE 7
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, N02 AND NOX
CONCENTRATIONS FROM STATIONARY SOURCES
C.
a
QC
>-
IU
u
2'
C
U
X
o
2
CREEK
e.o, PETFRSSURG C1D
e.et
o.ei
O.OJ
e.et
O I
7 ( « 10 11 11 II 14 IS 1C IT If I* 10 II II II
HOUR 0? DAY SEPTEMBER 1S7G - KJVEM3ER 1976
HOURLY AVERAGE N02 «0 AMD KOX CONCENTRATION CPPH)
&
0.
§
CREEK
e.o« EL12ASETHTOW C5)
O.OT
> 0.04
UJ
^
O e.e.
x
o.os
O 0.0
&*
HOUR OP DAY SEPTCHSER 1S76 - WOVEHSCR 1876
HOURLY AVERAGE W02 NO MQ NOX COKCENTRAT10N CPPM3
SOURCE; American Electric Power Service Corporation
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FIGDRE 8
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, N02 AND NO
CONCENTRATIONS PROM STATIONARY SOURCES
TAWCRS C3SEK
•••K
I
o ...
C3
§
S
C13
raua o?
!• it ta u i« ic u if te i* *o at
IS78 - PggftlKRy IS77
K32 W3 A*Ci FOX COPCEKTR/VTIOM CPWJ
S CRSEX
»•" I * • * 9 « 7 • » IO tl IS !• 1» 10 !• II1 IS 19 ti» Ct ti! »•
KXC3 C? OAT DETCEWSS? 1S7S - r5B^!/*.RY 1S7T
KUm-Y AV^RAC- M02 N3 AM3 K3K CCSCS4TRKTIQN (f.^-n
SOURCE; American Electric Power Service Corporation
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FIGURE 9
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, N02 AND NOX
CONCENTRATIONS FROM STATIONARY SOURCES
TANNERS CREEK
PETERSBURG CD
u
o
u
g
«.ot
0.04
0.0»
o.oa
O «.0|
WOX
o i
10 It It It 14 l» It 17 |* t» ft -II li 11
HOUR 0" DAY KARCH 1377 - MAY 1977
HOURLY AVERAGE N02 NO AND NOX CONCENTRATION CPPM)
_ TANNERS CREEK
S •.o«;7 ELIZABETHTO^N C53
KQX CONCENTRATION (PP
? ? f ?
3 3 t S
S ••«•
A*
2 «.o
(•
e
•u «»
— "^
"^^^k
i i
S,
—
/
/
f
^^^^
/
/
/
J^J
^
!OX
22
,'0
\
V
V
^V
\
\
\
^^
\
>
j
*«»,
1*^fc
\^
****
-
^=*
-^-
^
'
^
~*~
OU3 OF DAY Kf^CH 1S77 - KAY 1S7T
OJRLY AVftlRAIsZ K02 K3 AfO NOR CONCENTRATION CPPM3
SOURCE: American Electric Power Service Corporation
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10
AVERAGE DIURNAL VARIATIONS IN THE AMBIENT NO, N02 AND NOX
CONCENTRATIONS FROM STATIONARY SOURCES
~ 8.89
a.
u.
U*
tl
CRSHK
PSTSRS5UR3 C13
TZ^J
HOUR OF DAY
HOURLY AVSRAIS
1S77 - AUGUST 1ST7
N02 NO AND NOX CONCSHTRATION CPPM3
a.
a.
a
S
TANKERS
ELZZASETHTDKN £53
n e.es
ut
u
t.ts
i; t 2 3
HOJR OF DAY
HSJKLY AVERAGE
& u) tt i£ si i-» 10 te iv tw
JUKE 1S77 - AU8UST 1ST?
KC2 NO AND NOX CONCENTRATION CPPM3
Jai U ii
SOURCS: American Electric Power Service Corporation
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-22-
Tables 3 through 5 shew the five highest one-hour WO, and NO
^ j£
concentrations observed over a period of one year at four AEP
monitoring sites influenced by NO emissions from power plants
X
and the date and hour of their occurrence.
As can be seen, the NO, and NO maxima at these sites are
^ X
in general agreement with the monthly average diurnal curves.
That is, NO, peaks occur in the evenings and NO peaks in the
b J±
mid-morning. A closer look at the NO, maxima reveals several
peaks as well, sooner than the consistent evening bulge shown in
the average diurnal curves.
The meteorological conditions and the NO, conversion mecha-
nisms responsible for these trends are briefly outlined here and
are examined in more detail in the sections that follow.
The high NO concentrations occurring in the morning can be
X
understood in terms of fumigation conditions such as inversion
break up or plume trapping. But the NO, concentrations in the
morning are mainly governed by the initial oxidation of NO,
i.e., the direct oxygenation of NO. As can be seen from the
diurnal curves, the NO,/NO ratio for this time of the day is at
^ X
its lowest.
The observed peak N02 excursions in the afternoon, upon
analysis of the corresponding meteorological data, were found to
be associated with unstable atmospheric conditions. These
conditions result in occasional high ground-level NO concentra-
Ji
tions in the afternoon. The high NO, concentrations are a
result of both high NO levels and a greater fraction of NO in
X
the plume converted to NO, , The latter is driven by good atmo-
spheric mixing , which creates good conditions for oxidation by
both atmospheric oxygen and oxidants. The highest NO,/NO
^ X
ratios are found in the late afternoon or evening, with the
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TABLE 3
MAXIMUM NO AND NO CONCENTRATIONS AT
ft X
AEP - CARDINAL-TIDD PLANTS
MONITORING SITE: POWER (6)
Date
July 30, 1976
July 30, 1976
October 1, 1976
March 9, 1977
January 5, 1977
Hour Ending
13
12
19
20
17
5 Highest
1-hr. NO
Concentrations
(ppm)
0.180
0.128
0.087
0.079
0.079
5 Highest ,
Date
February 23, 1977
February 23, 1977
December 15, 1977
March 10, 1977
July 30, 1977
Hour Ending
9
10
9
8
13
1-hr. NOX
Concentrations
(ppm)
0.352
0.319
0.295
0.246
0.229
SOURCE; Data from American Electric Power Service Corporation
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TABLE 4
MAXIMUM NO AND NO CONCENTRATIONS AT
ft X
AEP - TANNERS CREEK PLANT
MONITORING SITE: PETERSBURG (1)
5 Highest
1-hr. NO
Concentrations
5 Highest
1-hr. NOX
Concentrations
Date
., 1977
15, 1977
:3, 1977
i, 1977
ir 3, 1976
Hour Ending
16
13
14
12
14
(ppm)
0.087
0.074
0.066
0.062
0.062
Date
March 4, 1977
May 10, 1977
October 30, 1976
December 5 , 1975
February 19, 1977
Hour Ending
14
11
9
11
6
(ppm)
0.23
0.142
0.126
0.119
0.114
SOURCE: Data from American Electric Power Service Corporation
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TABLE 5
MAXIMUM NO AND NO CONCENTRATIONS AT
AEP - GAVIN, HYGER CREEK, SPORN PLANTS
MONITORING SITE: LAKIN (3)
5 Highest
1-hr. NO^
5 Highest
Date
February 27, 1977
October 12, 1977
March 10, 1977
December 1, 1977
April 20, 1977
Hour Ending
3
14
21
20
13
Concentrations
(ppm)
0.075
0.069
0.069
0.062
0.062
Date
February 27, 1977
December 15, 1976
November 2, 1976
October 12, 1976
March 10, 1976
Hour Ending
3
11
13
14
9
Concentration!
(ppm)
0.278
0.245
0.189
0.189
0.172
3 ^
1
SOURCE; Data from American Electric Power Service Corporation
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-26-
upper limit to this ratio determined by the level of oxidants
.and the photochemical steady state of N02.
From this analysis, the following conclusions emerge:
• NO and NO, maxima occur during different
*V £»
periods of the day; whereas the NO maxima
X
show a trend of mid-morning excursions,
the N02 peaks occur in the afternoon-
evening most frequently.
• Diurnal variations in NO concentrations
Ji
are much more pronounced than those in NO- levels.
• The NO,/NO ratio varies from a low in
<£ a
mid-morning to a high in the early evening.
2) Seasonal Variation
Figures 11 through 16 show plots of the monthly highest
one-hour NO and NO, concentrations at the AEP and PEPCO moni-
X ^
toring sites. The following observations have been made:
• NO concentrations show significant seasonal
X
trends, with higher peak values occurring
in the colder months; and
• No consistent seasonal variation is observed
with respect to NO, concentrations.
3) Background Levels of NO,
The AEP Rockport station was a pre-construction monitoring
site and thus provides data on background levels. The diurnal
variation with hourly values averaged over a quarter and the
monthly peak one-hour NO and NO, values are shown in Figure 17,
X £,
-------
-27-
FIGOKE 11
AEP - TANKER CREEK PLANT
0.3 •-
0.2 -^
o.r--
PETERSBERG
MONITORING SITE (1)
Sept. Oct. Nov.
1976
0.3 ••
0.2 "
0.1 "
Dec. Jan. Feb. Max. April May June July Aug.
1977
MONITORING SITE (5)
Sent. Oct. Nov. Dec. Jan. Feb. Mar. April May Jnne July Aug.
1976 1977
' - MONTHLY HIC3EST 1-HOUR NOjj AND NO2 LEVELS
SOURCE; Data from American Electric Power Service Corporation
-------
-28-
0.31
2-
04
0.2'
O.-lf
FIGURE 12
AEP - GAVIN, KYGER CREEK, SPORN PLANTS
MONITORING SITE (3)
NO.
July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. April May June
1976 1977
X 0.2 "
cu
cu
0.1 •
MONITORING SITE (7)
SOURCE:
July Aug. Sept. Oct. Nov. Dec. Jan. Feb. Mar. April
1976 1977
MONTHLY HIGHEST 1-HOUR NOX AND N02 LEVELS
Data from American Electric Power Service Corporation
-------
-29-
FIGOHE 13
AEP - CARDUCa/TIDD PLANTS
0.3
0.1- •
DTOUSTRIAL AREA SITE (2)
NO,
-t"
0.3...
ST 0.2 t
dl
0.1"
May June July Aug. Sept. Oct. Nov. Dec. Jem. Feb. Mar. April
1976 1977
trox
INDUSTRIAL A5EA
SITE (6)
""May June July Aug Sept. Oct. Nov. Dee. Jan. Feb. Mar. April
1976 1977
MONTHLY. HIGHEST 1-HODR NOX AND NO2 LSVEI£
SOURCE; Data from American Electric Power Service Corporation
-------
-30-
FIGORE 14
AEP - AMOS PLANT
£
0.
0.1!
SITE: FISHER RIDGE (2)
NO-
Sept. Oct. Nov. Dec. Jan. Feb. Mar. April May June
1976
0-
NO
AEP - MITCHELL S RAMMER PLANTS
SITE: MCCLAIN RDN (5)
Nov. Dec. Jan. Feb. Mar. Apr. May June July
MONTHLY HIGHEST 1-HOUR NOX AND N02 LEVELS
SOURCE; Data from American Electric Power Service Corporation
-------
0.1. "
z
0.05 •'
-31-
FIGURE 15
PEPCO-- CHALK POINT
Total Capacity i 1260 MW
3 Stacks: 400 Ft.
400 Ft..
700 Ft.
MAXIMUM 1-HOOR CONCENTRATION
Mar. April May June- July Aug. Sept. Oct. Nov. Dec.
Higfaea
0:20 r
0.15 "
* 0.1 f
a.
0.05
PEPCO'- DIOCERSON PLANT
Total Capacity: 540 MW
2 Stacks: 400 Ft.
400 Ft.
MAXIMUM 1-HOUR CONCENTRATION
Mar. April May June July Aug. Sept. Oct. Nov. Dec.
MONTHLY HIGHEST 1-HOUR NOX LEVELS
-°URCE: Data fr°m Potomac Electric Power Company
-------
-32-
FIGOFE 16
PEPCO - MORGANTOVm
o.i
0.05 T
Total Capacity: 1000 MW
2 Stacks: 700 Ft.
700 Ft.
Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
MONTHLY HIGHEST 1-HODR NOX LEVELS
SOURCE; Data from Potomac Electric Power Company
-------
0.-1--
I
o.
-33-
P1GURE 17
SOCK PORT SHE
MONITORING SITE (1)
t t 1 j 1 1 < 1 1 1 ' k—
May June July . Aug. Sect. Oct. Nov. Dec. Jan. Feb. Mar. Apr.
1976 - 1977
— 0-.2-..
O.I--
cu
cu
MONITORING SITE (2)
•4-
May June July Aug. Sept. Oct. Nov. Dec. Jan. Feb.
1976 1977
MONTHLY HIGHEST 1-HOOR NCX AND N02 LEVELS
SOURCE; Data fron Potomac Electric Power Company
Mar. Acr.
-------
-34-
Peak NO- concentrations at this site averaged around 80
3 3
yg/m and have been observed to be as high as 140 yg/m . Annual
average NO- concentrations were on the order of 20 yg/m .
However, there are several small power plants west and southwest
of these receptors within a distance of 15 to 30 miles, thus
making these values suspect as true measures of natural back-
ground NO-.
b. Modeled Relationships Between NO- and
£»
NO
Simple approaches have recently been used to translate the
ambient concentrations of NO due to point sources, as estimated
by dispersion modelling, into NO- levels. One of these ap-
proaches assumes that the maximum NO- observed at any receptor
in a field about a point source approximates a fixed fraction of
maximum NO of any receptor, irrespective of the various factors
Ji
affecting the formation of NO-. The conversion factor is de-
rived from either the ratio of measured NO- to NO at a receptor
^ X
influenced by a point source, or by relating estimated NO
J^
concentrations at a receptor to the NO- concentrations measured
there. This approach may be sufficient for estimating the
maximum impact of individual point sources at a single location.
But the degree to which multiple sources impact a receptor
~v"aTie~s~with plume travel time to the receptor. The N00/N0
^ H
relationship in a plume changes continuously, especially during
the first 30 to 60 minutes after plume discharge. It is, there-
fore, not valid to use a fixed translation factor while assess-
ing the air quality due to several interactive point sources.
A second approach for estimating the NO- concentrations
from isolated point sources suggests that, except for the ini- .
tial conversion of NO to NO- (about ten percent) due to thermal
oxidation, further conversion of NO is limited by the ambient
-------
-35-
levels of ozone. The NO. concentration at a receptor due to an
isolated source is expressed, therefore, by the relationship
below:
NO- . = 0.1 N0v + 0. (1)
^ X O
(concentrations at (concentrations at (concentrations in the
a receptor, ppra) a receptor, ppm) vicinity, ppm)
The above approach has several limitations. High ambient N02
concentrations due to point sources are common in winter when
the ambient 0, levels are at their lowest. This certainly
downplays the role of ozone as the only limiting factor in the
conversion of NO to NO-. It also seems likely that N02 forma-
tion from thermal oxidation accounts for a major portion of NO-
concentration when ground-level NO maxima occur during poor
X
atmospheric mixing and/or short travel times. Under these
conditions, the conversion of NO in the plume due to ozone is
limited by the extent of plume mixing with the surrounding
atmosphere rather than by the ambient level of 0_.
The initial conversion of HO to NO- could be higher than
ten percent of the initial NO levels. It is, for the most
Ji
part, a function of the NO concentrations in the stack gas.
a
The conversion of NO to NO- in the flue gas before exhaust is
not limited because of oxygen deficiency, but due to unfavor-
ably high temperatures. The concentration of oxygen in most
flue gases is in the order of 30,000, while the NO levels range
a
only up to 1,000 ppm. The NO to N02 conversion can be explained
by the following two-step reaction mechanism:
NO + 02 ^ N03 (2)
N03 + NO *"" 2N02 (3)
-------
-36-
The effect of high temperature on reaction (3) is to decrease
the equilibrium concentration of NO,, thereby limiting N02
formation. Once the plume discharges into the atmosphere,
lowering of temperature and the continued availability of addi-
tional oxygen results in rapid conversion of NO to N02 at a rate
proportional to the square of NO concentration. As mentioned
earlier, at NO concentrations above 100 ppm, the oxidation of NO
by oxygen is reported to be rapid. But it slows down to a less
significant rate as the NO concentrations reach 1 ppm. Plume
centerline NO- concentrations in the range of 25 percent of the
NO concentrations within one to two minutes of plume discharge
a
have been reported in the Four-Corners Power Plant plume stud-
ies. "/
As a plume disperses further, or its time travel increases,
the rate of NO conversion is controlled by the level of oxi-
dants. But given sufficient time, almost all NO in a plume
should be converted to N02 due to recurring encounters with
fresh parcels of ozone-(or other oxidant-)containing air. The
depletion of ozone is complete (as suggested by equation (1))
during the absence of ultra-violet radiation. In the presence
of sunlight, however, a photochemical equilibrium between NO,
NO-, and ozone is established. Thus, the use of the highest
daily 0- concentrations in equation (1) is not justified since
they occur during periods when the solar UV-flux is maximum—
total conversion of NO to NO- is implied at the same time that
photochemical dissociation of N02 is maximized. Further, the
presence of other oxidizing radicals in the summer, as well as
in the winter, are not accounted for by the measured 0., concen-
trations.
We may be able to predict the order of magnitude of N0~
concentrations due to isolated point sources in the summer using
-------
-37-
this approach. And assuming little seasonal variation in the
peak NO- concentrations, the predicted NO. concentrations could
be considered a "worst case" estimate of the impact of a point
source during a year. The approach has been tested only on a
limited basis and its correlation with observed N0_ concentra-
tions is yet to be shown. Furthermore, this approach is only
suggested for application to isolated sources; it cannot assess
the interactive impact of multiple sources as it does not ac-
count for the variation in the NO,/NO ratio with travel time in
j£ X
a plume.
A third approach and the one suggested here involves pre-
dicting the NO-/NO relationship in individual plumes at differ-
" J»
ent points in time for a given set of meteorological conditions
and background oxidant levels. The relationships are developed
for those meteorological conditions and for oxidant levels at
which highest NO- concentrations,, due to point sources, have been
observed. Simultaneous measurements of NO, N0~, and 0, across
power plant plumes in different parts of the country have re-
cently been made. ' ' The time for 50 percent conversion
of NO to NO, in plumes with varying initial NO concentrations,
^ X
and different meteorological conditions and background ozone
concentrations, has been found to range between 10 to 60 min-
utes. The range of values can be explained in terms of the
observed variations in the ambient ozone concentrations, solar
ultra-violet radiation, wind speed, atmospheric stability, and
initial NO concentrations in the plume.
J£
The general shape of the curve relating N02/W0 to plune
travel time based on plume studies is as shown in Figure 18. As
discussed earlier, the rate of conversion during the first one
to two minutes of plume discharge is dependent on the initial NO
-------
-38-
FIGURE 18
THE RELATIONSHIP OF NO AND NO. IN
x 2
A POINT SOURCE PLUME AS A FUNCTION OF TIME
0.9
NO,
i
NO"
0.5
0.05
B
Curve B reflects
a higher initial
NO., concentration
60
120
180
Minutes
SOURCE; Energy and Environmental Analysis, Inc.
-------
-39-
concentration in the plume.* It has been generally accepted
that further conversion of NO to NO. in a plume is controlled by
the rate of mixing of the plume with the ambient air, rather
than by the kinetic rate constant of the reaction of NO with
147
ambient ozone (oxidants). ' Given sufficient time, almost all
NO in a plume should be converted to NO. with continuous in-
fusion of fresh oxidant-containirig air into the plume as it
travels.
Expressed in mathematical terms:
NO. concentration at time t = f (initial NO concentration,
« Ji
plume diffusion, ambient oxidant concentrations, solar UV-
flux, and plume travel time t)
For a given set of meteorological conditions and ambient oxidant
concentrations, the NO-/NO ratio at time t in individual plumes
^ X -~
can be assumed to be mainly a function of the initial NO con-
4V
centration and diffusion characterized by travel time:
/jV\ = f (NOX);.
01077 t x if t (4)
V A / w
In Figure 18, curve B approximates the impact of higher 110
-""" ™ •" *— jt
emissions on the NO,/NO relationship. Initial NO to NO-
4b X fc
conversion is faster since the rate is proportional to the
square of NO concentration. But later on as the plume diffuses,
the amount of NO converted to NO- is limited by the rate of
mixing with the surrounding atmosphere. Allowing sufficient
*Under normal diffusion conditions, NO concentrations in most
power plant plumes should drop below 100 ppm levels within one
to two minutes of discharge.
-------
-40-
time, almost all the NO in a plume is converted to NO- by
repeated mixing with fresh parcels of oxidant-containing air.
In an urban atmosphere characterized by high levels of reactive
hydrocarbons, however, competing reactions will limit the
resulting concentrations of NO-.
Lack of sufficient NO,, and NO data for individual plumes
£» rf»
under similar meteorological conditions did not allow the
specification of separate N02 conversion curves for various
initial NO concentrations. Instead, a base curve for an
Ji
initial NO concentration of SOOppm was derived from power
H *l *3 T A f
plant plume studies '
-------
-41-
FIGURE 19
N02/N0x RELATIONSHIP IN POINT SOURCE PLUMES
WITH DIFFERENT INITIAL NOx CONCENTRATIONS
0.0
20
I
40
I
50
30
TIME IN MINUTES
SOURCE: Energy and Environmental Analysis, Inc.
T
60
70
-------
-42-
Further conversion of NO, as the plume travel time increases,
is considered to be mainly dependent on plume diffusion (mixing).
For a certain level of ambient 03 concentration and under
similar meteorological conditions, only a fixed amount of NO is
assumed to convert to N02 per unit time. This amount was
estimated directly from the base curve and added to the N02
levels estimated after five minutes, to generate the other
curves.
Because of time constraints, a composite equation express-
ing all curves could not be developed. Instead, the specific
curves were used to represent five ranges of initial NO con-
Jt
centrations. A piece-wise linear approximation of each was
used for modeling purposes.
A limited test of this approach on power plants with
short-term ambient N02 data showed good correlation between
predicted and observed NO- concentrations.
The reactive photochemical models presently being developed
are sinply too sophisticated and expensive to use for studies
involving a large number of sources. The approach presented
here is simple and theoretically justifiable. For the limited
use for which it was intended (i.e., to predict the N02 concen-
trations from point sources under adverse meteorological condi-
tions) , it adequately represents two of the important variables
(the initial NO concentrations and the travel time) affecting
X
the N02 concentrations.
Constraints on time and lack of experimental data on point
source plumes prevented proper validation of these curves.
Further validation and generalization of the approach is intended
as more ambient N02 data around point sources and data on point
source plumes become available.
-------
-43-
The generalizability of the curves in Figure 19 is a
function of the range of environmental conditions prevailing
during the plume studies (on which the curves are based). In
general, the plumes studied were influenced by a fairly good
mixing environment (typical summer afternoon condition) and 03
concentrations around 0.10 ppm. For conditions considerably
different than these (e.g., morning inversion break-up or high
0- levels), the shape of the curves may be altered.
c. Expected Point Source Impacts
Several model plants (sources of NO emissions) were de-
•A
veloped to estimate the types of point sources which might be
expected to produce high short-term HO, concentrations. These
plants were modeled using PTMAX to estimate maximum NO .
Ji
'(Details of specific point source modelling appear in Volume II
of this report.) The overall results are shown in Table 6.
As can be seen from this table, the facilities most likely
to produce high N02 levels are characterized by a combination
of short stacks and low exhaust flows and/or multiple sources
at a single plant. These combinations are likely to be char-
acteristic of large industrial facilities such as iron and
steel mills, petroleum refineries, or large numbers of industrial
boilers at a single plant.
Power plants, due to higher stacks and high flue gas ex-
haust rates, are not likely to cause high levels of short-term
N02. The exception to this could occur where the plume inter-
sects a hill or valley wall nearby. Although terrain im-
paction typically reduces plume transport time and thus the
degree of NO/NO- conversion, high NO values can lead to
• Jt
significant levels of N02.
-------
-44-
TABLE 6
ESTIMATES OF MAXIMUM AMBIENT NO, CONCENTRATIONS FOR SINGLE STACK FOSSIL FUEL USER MODEL PUNTS1
PLANT SIZE(MW(e)]
(Fuel Type2)
2000 (c)
2000 (o)
2000 (g)
400 (c)
400 (o)
400 (g)
200 (c)
200 (o)
200 (g)
100 (e)
100 (o)
100 (g)
50 (c)
50 (o)
50 (g)
20 (c)
20 (o)
20 (g)
10 (c)
10 (o)
10 (g)
5 (c)
.5 (o)
5 (g)
0.1 (c)
0.1 (o)
• 0.1 (g)
STACK HEIGHT [ft]
Ranqe of
Estimates
430-660
430-660
430-660
200-430
200-430
200-430
110-430
110-430
110-430
110-200
110-200
110-200
6S-200
65-110
65-110
30-110
30-110
30-110
30-110
30-110
30-110
30-110
30-65
30-65
30-65
30-65
30-65
Best Estimate
660
430
430
430
200
200
430
200
200
200
110
110
200
110
110
110
110
110
110
65
65
£5
65
65
65
30
30
STACK TEMPERATURE [°F]
Range of
Estimates
280-330
280-330
280-330
280-330
280-330
280-330
280-330
280-330
280-330
280-530
280-530
280-530
280-530
280-530
280-530
280-530
280-650
280-650
280-650
280-800
280-800
280-800
280-800
280-600
280-800
280-800
280-800
Best Estimate
300
300
300
300
300
300
300
300
300
330
330
330
330
350
350
400
470
470
470
530
530
530
530
530
530
530
530
MAXIMUM NO, CONCENTRATION fug/m3!
Range of
Estimates
130-220
85-140
75-130
110-270
85-250
80-230
110-350
40-220
40-180
70-300
30-140
20-75
80-360
90-250
50-130
110-290
30-330
15-180
20-180
20-200
10-50
20-140
30-150
10-50
5-30
20-60
5-15
Best Estimates
150.
130
120
130
220
210
130
120
110
120
120
60
110
130
70
160
35
20
50
80
20
45
50
15
10
40
10
1. Assuming:
(1) Constant ratio of flow rate to Btu's fired developed from combustion calculations, assuming
1 MM(e) equivalent to 10 million Btu/hr, for each fuel type as follows:
(a)
1.00 srn^/s per MU(e) for moderate sulfur bituminous coal (-721 C. 4.51 H, 51 0?,
1.5S NZ, 2X S. 61 H20, & 9S ash) burned with 22X excess air (average of 3 cases);
(b) 0.66 smVs per MH(eT for California Bunker "C" fuel oil (87. 9X C, 10.3S H2, 1.3 S,
0.51 0;. S 0.1Z Nj) burned with 191 excess air;
(c) 0.73 snrVs per MW(e) for natural gas (-881 CH4, 81 C2H6, 81 N2)
excess air (average of 2 cases);
burned with 141
(2)
Emission rate calculated for total capacity of unit as firing rate and for maxima emission
factor given for any type of boiler of the fuel type in the size range as given in AP-67
(1977): . ,
(a) Coal S-2000 MW(e): 1.66 lb/10° Btu for wet-bottom cyclone utility or industrial
boiler; ,
Coal 0.1 NW(e): 0.25 lb/10 Btu for packaged firetube firebox stoker;
Oil 200-2000 MW(e): 0.75 lb/106 Btu for horizontally opposed or front wall, vertical.
or cyclone firing field erected water tube utility boilers;
Oil 20-100 MW(e): 0.573 lb/106 Btu for horizontally opposed or front wall, vertical,
or cyclone firing field erected water tube utility boilers;
Oil O.l-lOMM(e): 0.43 lb/106 Btu for packaged firetube or water tube conoereial
boilers firing residual;
Gas 200-2000 MW(e): 0.70 lb/106 Btu for horizontally opposed or front wall firing
field erected water tube utility, boilers;
Gas 20-100 MW(e): 0.301 lb/106 Btu for field erected water tube Industrial boilers
firing natural aas; ,
Gas 0.1-10 MW(e): 0.103 lb/106 Btu for packaged fire tube or water tube conercial
boilers.
(3) Maximum ambient concentrations generated for any meteorological conditions and distance downwind
using the PTMAX model with "reasonable" stack heights and temperatures for the unit size and
fuel type and a single stack for one unit. As an incomplete set of PTMAX runs were nade for the
numerous combinations of stack height, temperature, and flow rate considered, many of the extreme
and best estimates were by extrapolation or interpolation, to that the concentration* given are
very approximate.
2. fuel type: (c)- coal, (o)- oil, (g)- Natural gas.
(b)
(c)
(d)
.(e)
(f)
(g)
(h)
SOURCE: Energy and Environmental Analysis, Inc.
-------
-45-
2. Area Sources
a. Ambient Concentration Patterns
The spatial and temporal patterns of ambient N02 levels
resulting from area source emissions differ somewhat from those
due solely to point source emissions. Our knowledge of these
patterns is based on the continuous record of ambient N02 at
those monitors which, due to their location, are unlikely to
reflect point source contributions. In urban areas, these
include most continuous monitors.
Washington, D.C., an area source-dominated urban area
(over 70 percent of total NO emissions come from area sources),
X
provides an exceptionally good opportunity to profile ambient
air pollution arising from area source emissions. Tables 7
through 9 show monthly peaks (highest and second highest hourly
values), and annual averages for three stations in the Washing-
ton, D.C. area. These stations reflect a variety of area
source settings—office complexes, high-vdlume transportation
intersections, suburban commercial centers—yet they display a
remarkable uniformity in recorded concentrations. This is due
to (1) a relatively even spread of area source emissions,
and/or (2) a spatial smoothing effect due to the relatively
slow rate of NO- formation from NO. The lack of correspondence
between NO and NO- levels at single points in time supports the
latter interpretation.
Figures 20 through 22 provide further evidence for the
similarity of ambient NO- levels at these monitors, and suggest
possible explanations for the patterns observed. Figures 20
and 21 show diurnal variations during typical summer days at
two of the stations. Values shown are concentrations for each
hour averaged over an entire month. These are days when ozone
-------
-46-
TABLE 7
MONTHLY TIME TRENDS TN HOURLY NO AND NO CONCENTRATIONS
LEWINSVILLE STATION
WASHINGTON, D.C. AREA IN 1977
Highest NO Corresponding Highest 2nd Highest
Month (yg/m3) N02 (ug/m3) N02 (ug/m3) N02 (yg/m3)
January 680 65 130 125
February 630 65 290 225
March
April 615 95 190 180
May 380 120 290 255
June 290 180 225 205
July 290 75 170 140
August 650 10 280 265
September 515 75 280 235
October 580 40 160 150
November 700 45 140 130
December 680 75 130 120
Annual Average NO.: 56 yg/m
Second Highest N02: 280 ug/m3
Peak/mean - 5.0
SOURCE: Data from local pollution control agencies,
-------
-47-
TABLE 8-1.
MONTHLY TIME TRENDS IN HOURLY NO AND N0_ CONCENTRATIONS
MASSEY BUILDING
WASHINGTON, D.C. AREA IN 1977
Highest NO Corresponding Highest 2nd Highest
Month (Pg/m3) NOo (yq/m3) NO? (ug/m^) NO? (yq/a3)
January 655 140 160 150
February 650 105 190 170
March 350 105 140 130
April 230 120 160
May 40 20 180 130
June 80 85 170 160
July 20 65 85 75
August 70 95 75
September 125 • 95 115 . 105
October 420 75 225 130
November 680 43 115 105
December 645 120 120 115
Annual Average N02t 40 yg/m
Second Highest IK^s 190 yg/m
Peak/mean =4.8
SOURCE: Data from local pollution control agencies,
-------
-48-
TABLE 9
MONTHLY TIME TRENDS IN HOURLY NO AND NO CONCENTRATIONS
SEVEN CORNERS STATION
' WASHINGTON, D.C. AREA IN 1977
Highest NO Corresponding Highest 2nd Highest
Month (tig/m3) N02 (ug/m3) NO? (yig/m3) NO^
150 120
205 145
120 110
265 195
190 170
140 130
170 150
235 150
205 • 170
160 150
January
February
March
April
May
June
July
August
September
October
630
620
540
655
240
170
185
320
505
420
10
50
0
0
40
20
55
105
105
85
Annual Average N02: 46
Second Highest NO2: 235
Peak/mean =5.1
SOURCE; Data from local pollution control agencies
-------
NO, NO.,
(ppm)
0.035-
0.030-
0.025-
0.020
0.015
0.010
0.005-
FIGURE 20
AVERAGE HOURLY NO AND NO CONCENTRATIONS FOR JULY 1977
(Engleside Station, Washington, D.C. Area)
NO
NO,
-I r
-i 1 -, , 1 p-
6)8 10
12
Hours
~1 • T
14 16
18
r~
20
24
VO
I
U"'
ta ,c---m ?.-"--il 'lui'* i c' ' rol -
-------
FIGURE 21
AVERAGE HOURLY NO AND NO2 CONCENTRATIONS FOR JANUARY 1977
(Engleside Station, Washington, D.C. Area)
NO, NO,
4
(ppra)
1.0000 -
0.0875 -
0.0750 -
0.0625 -
0.0500 -
0.0375 -
0.0250 -
0.0125 -
NO
NO,
I
4
I
6
I
8
10 12
Hours
14
16
18
I
20
I
22
24
o
I
SOURCE: Data from local pollution control agencies
-------
FIGURE 22
AVERAGE HOURLY NO AND NO CONCENTRATIONS FOR JUNE 1977
(bewintrvilla Station, Washington, D.C. Area)
NO, NO
(ppm)
0.05-1
0.04-
0.03-
0.02-•
0.01 •
\
\
\
I
ui
10
12
14
16
18
20
22
24
SOURCE: DaLa from Tonal noTJnHon
-------
-52-
levels are likely to be high. NO and NO- levels both fall
after midnight due primarily to low NO emissions and to
X
atmospheric dilution. If 0_ (or other oxidant) levels are ini-
tially also low, NO will build up rapidly in the morning in
concert with traffic levels, while the rise in N02 lags behind
the HO buildup. The resultant N02 peak in early to mid-morning
then subsides as photo-dissociation becomes a balancing factor.
In both Figures 20 and 21, afternoon NO levels are shown to be
fairly lov; (due to high 00 , while NO- has reached a steady
state level. With the reduced UV insolation in late afternoon
and evening and the increased NO emissions from rush-hour
J^
traffic, NO- begins a rapid rise followed by or simultaneously
with an NO increase as 0., is depleted.
Wintertime diurnal variations are similar, with NO levels
showing the same daily variation corresponding to traffic fluc-
tuations. Figure 22 shows that the peaks in N02 are somewhat
muted, though still obvious. W,ith reduced UV radiation, lower
temperature, and low 03 levels in the winter, NO. concentrations
are limited by slower conversion rates and atmospheric dilution.
The EPA (OAQPS, MDAD) has recently reviewed patterns of
197
hourly NO,, levels in several urban areas. / They have
labeled the morning peak "photo-chemical synthesis" and the
afternoon peak "ozone titration", though the processes which
lead to each are both obviously related to photochemistry.
In addition, they stress the importance of "carry-over" NO-—
high levels of NO- formed one day which are not depleted
when new NO- production begins the next. The highest hourly
NO- levels observed are likely to be a result of NO- "build-
up" over several days.
-------
-53-
b. Potential Violations of Short-Tern Standards
If continuous 110- monitors were common in all AQCR's, the
likelihood of any AQCR violating the various suggested short-
term N02 standards could be determined with ease. Unfortunate-
ly, continuous monitors are not common. As a consequence, the
potential for violation must be judged from 24-hour readings or
annual averages. Evidence is now available to suggest that the
relationship between one-hour peak (second highest hourly)
readings and annual averages for area source-dominated monitors
is less than six to one. Figure 23 shows the distribution of
peak to mean NO- .ratios averaged over the years 1972, 1973,
.--. .._ .. _ .£ _. ._ 1 A -T 7 X
and 1974 for 120 urban sites. '' It is further reported
that for continuous monitors in central city commercial or
residential areas, the average peak (maximum) to mean ratio
lies between six and seven. ' Area sources are undoubtedly
the major contributors to the N02 concentrations at these
sites, although point sources in the region also have some
impact. The ratio due to the area source impact alone should
thus be below this average value. The peak to mean value of
six, therefore, seems to be associated with sites impacted
predominantly by area sources. The urban area monitors reporting
peak to mean ratios of over six are believed to be impacted by
point sources significantly and should not be used to characterize
short-term N02 problems from area sources.
In order to estimate the fraction of AQCR's likely to
violate alternative N02 one-hour standards as a result of area
source emissions alone, short-term NO. concentrations were
estimated for each AQCR. This estimate was set equal to the
highest second high one-hour concentration recorded at any
continuous monitor, from 1972-1974, the peak to mean ratio of
-------
-54-
FIGURE 23
30% -
20% -
u.
o
u
oe
10% -
T
2
8 10 12 14
MAXIMUM/MEAN RATIO
16
18 20
Distribution of maximum/mean NOj ratios for 120 urban locations
averaged over the years 1972, 1973, and 1974.
SOURCE: Reference 16
-------
-55-
which was 6:1 or less. If no continuous monitor in the AQCR
fits this criterion, then the short-term estimate was set
at six times the highest annual average of all monitors with
a sufficient number of data points. An annual average is
calculated only if at least 165 percent of.'.the total possible
hourly values' are recorded at a~-site- during a given year.
The results are shown below. Only at a one-hour standard
of 250 yg/m is it probable that an appreciable number of AQCR
would be in violation due to area source emissions alone.
. Estimated Number of AQCR's Not Attaining the Standards
250 yg/m3: 95
500 yg/m3: 17
750 yg/m3: 2
1,000 yg/m : 0
3. Alternative Ways to Express the Short-Term Standard
Short-term NAAQS are normally expressed as a concentration
(averaged over the specified sampling time) which cannot be ex-
ceeded more than once per year. The one allowed excursion is
justified on the basis of unusual unrepresentative meteoro-
logical or emission conditions that may be experienced in any
AQCR. However, it is unlikely that these conditions would
occur just once or not at all each year. Fumigation episodes,
inversions aloft, or similar events which can lead to high
ground-level concentrations of airborne materials tend to
behave like random variables. That is to say, the average
occurrence over a long period of time may be once a year, but
multiple yearly occurrences could, and in fact would be expected
to occur occasionally. Thus, the standard should be expressed
in statistical terms (e.g., "cannot be exceeded on the average
more than once a year").
-------
-56-
Determining when a violation of a statistically-based
standard has occurred is more problematic since a violation
will only occur if the number of excursions above the standard
is higher than would be expected for that AQCR. Thus, a frequency
distribution of pollutant concentrations nust be derived from
recorded data in each AQCR. The distribution is then adjusted
so that the standard concentration will occur no more than once
a year on the average (is likely to occur no more than once in
3,760 hours per year for a one-hour standard). The probability
that two, three, or more excursions could occur can then be
read directly from the frequency distribution. If the number of
excursions actually observed over several years is considerably
higher than the expected number (one in this example), then the
AQCR can be said to be in nonattainment.
EPA has estimated the frequency distribution of ozone
concentrations for several AQCR's using the Weibull function.
Unfortunately, a similar analysis of N02 data has not yet been
made, so that little can be said about the nature of these dis-
tributions.
In addition to using statistical terminology in expressing
the N02 standard, the number of allowable times the specified
concentration is most likely to be exceeded can also be varied.
If occasional high concentrations do not pose a health risk
(e.g., if chronic, rather than acute, exposure to levels above
the standard is the primary health concern), then more than one
expected excursion per year can be allowed. The choice must be
based on a combination of health effects and monitored/modelled
ambient air quality days.
-------
APPENDIX A
-------
o
a
H-
H
o
00 hr)
Z H
« 2
5
H,
r»
tr
o
n
»
H
P.
H'
NEW ALEXANDRIA
EL. 1260*
TIDO
CARDINAL
3FOWLERSTOWN
EL.1230 '
WELLSBU^G
°4
MEADOWCROFT
, VILLAGE
'
CARDINAL/HDD PLANTS
PLANT ELEV. 675*
> STACK HEIGHT ELEVS.
STK HO. CARDINAL TlOD
BEECH
BOTTOM
EL. 730*
West
Virginia
Legend
D POWER PLANT
O
O SO, -f NOB
O~ SO, -f PARTICULATES
Q SO, + COM
SO, -f WIND
A VISIOMETER
TOWER
O5
BETHANY
All EUvalloni
Are Abova Mean Sea Level
i
en
-------
-58-
10
SPORN
COOLVILLE
EL, 800*
KYGER CREEK
(OVEC)
Ohio
O-WOLFPEN
" EL. 900'
8
O-FfVE POINTS
EL. BOO'
M'ASON
LAK1N
EL. GOO'
NEW HAVENO-
EL.800' V»
GAVIN
POWER PLANT./
PLANT ELEV. 567' ''
STACK HEIGHT ELEV. 1667*
•KYGER CREEK
POWER PLANT
PLANT ELEV. 578'
STACK HEIGHT ELEV. 1116*
9
. -O-OORCAS
• SPORN B-720'
POWER PLANT
PLANT ELEV. 586's*
STACK HEIGHT ELEV. 1186'
NEPTUNE
EL. 910'
MOUNT ALTO
7 EL. 930'
O-HENOERSON
O EL. 558'
WCst
Virginia
All Ctoovtlem
Ar« Ak*v* Mean
3 4 MILES
Legend
POWER PLANT
PART1CULATES
S02'+ RAIN GAUGE
S02 -t- VISIOMETER
S02-t-WINO
Gavin -
FIGURE A- 2
Kyger - Spom Monitoring Network.
-------
-6B-
MITCHELL & KAMMER
McCLAIN RUN
EL. 1300'
BLAIRS RIDGE
EL. 1340' .
0-6
2
GRAVE CREEK
EL. 1230'
PLANT ELEV.
STACK HEIGHT ELEV.
NOS.I&2 1245'
GERMAN RIDGE
EL. 1240' .40?
'KAMMER
MITCHELL
PLANT ELEV. 6S6
STACK HEIGHT ELEV. 1866
O-B
4. L.U BOWMAN
t f PI iAnn'
EL, 1400
West Virginia
Legend
POWER PLANT
O.so2
(I) SOZ + NO,
TSP
WIND
TOWER
N
FIGURE A-3
All Elevations
Art Above Mean Sea Level
•^*
3MH.C3
Field Monitoring Network in the Vicinity of the Mitchell and
Kamraer Power Plants. McClain Run (5) started operation on
December 30, 1974 and German Ridge (1) started operation on
January 7, 1975.
-------
r»
0
rt
rt
M
rt
t»
>
n
Ul
H*
JJ
H-
n
n
£
n
o.
H-
H
n
n
rt
o
a
M
0
M»
s.
Jj
0-
!«••«•>
•I***
-------
-61-
OH*
I
(I
I I
' I.
KILBY ROAD
EL. 515'
^TANNERS CREEK
1 5 ELIZA8ETH70WN
Q~ EL. 500'
Indiana
LAWRENCEBURG
EL.465* °>
WILSON CREEK
EL.8IO'
BO-
Kentucky
TANNERS P. P.
-?/>TANNERS CREEK
PLANT ELEV. 497'
STACK HEIGHT ELEVS.
1-3 770'
4 1047'
1 PETERSBURG
EL. 510'
DUTCH HOLLOW
EL. 810'
All Elevations
Are Above Mean Seo Level
i
? MILES
Legend
C3 POWER PLANT
O so,
O" SOj^ PARTJCULATES
W WIND INSTRUMENTS
R3 TOWER
FIGURE A-5
Field Monitoring Network in the Vicinity of the Tanners Creek.
-------
•-• "••
!•*!••»
/ ••
\
^ROCKPORf SITE
N
All Elavollont
Ara Above Meon Sea Laval
0 I ( MILES
;i
/ i
EVANSTON
o EL. 480* •
30
ROCKPORT
EL. 405r
CHESTNUT GROVE
SO, + PARTICULATES
.ROCKPORT
I
cr\
FIGURE A-6
l;icld Monitoring litjulpinont in .tho Vicinity of the Rockport Site.
Directions arc tlioso of tlio wind that would blow from the plant
tf e s. .Ion.
-------
-63-
REFERENCES
1. Memorandum from Joseph A. Tikvart (EPA Source-Receptor
Analysis Branch) to Edward J. Lillis (EPA Air Management
Technology Branch), February 16, 1978.
2. Control Techniques for Nitrogen Oxide Emissions From
Stationary Sources—^Revised Draft Second Edition. Aerotherm
Report TR-77-87, December 1977.
3. The National Air Monitoring Program; Air Quality and Emis-
sion Trends. EPA, December 1977.
4. Calvert, J.G. (1973), Interactions of Air Pollutants. Pro-
ceedings of the Conference on Health Effects of Air Pol-
lution , National Academy of Sciences, 19-101, October 3-5.
5. National Academy of Science, Air Quality and Stationary
Source Emission Control, prepared for the Committee on
Public Works, United States Senate, Serial No. 94-4, March
1975.
6. U.S. EPA National Air Quality and Emissions Trends Report,
1975, EPA No. 450-11-76-002, November 1976.
7. Roger Morris, "Nitrogen Dioxide Problem Areas", March
1978.
8. Code of Federal Regulations, Section 40, Part 60.
9. Section 202(b)(1)(B), Clean Air Act of 1977, (42 U.S.C.
1857, et seq.).
10. EPA, '"Uses, Limitations, and Technical Basis of Procedures
for Quantifying Relationships Between Photochemical Oxidants
and Precursors," EPA-450/2-77-021a, November 1977.
11. Ambient Monitoring data obtained from American Electric Power
Service Corporation, Canton, Ohio.
12. Ambient Monitoring data obtained from Potomac Electric
Power Company, Washington, D.C.
-------
-64-
13. "Ozone and Nitrogen Oxides in Power Plant Plume," D. Megg,
P.V. Hobbs, L.F. Radke, and H. Harrison, International
Conference on Photochemical Oxidants, August 1977.
14. Davis, D.D., G. Smith, and G. Klauber (1974), "Trace Gas
Analysis of Power Plant Plumes via Aircraft Measurement:
0-., NO , and SO, Chemistry," Science 186; 733-736.
O X ^ ™ —"
15. Thuillier, R.W., W. Viezee, Air Quality Analysis in Support
of a Short-Term Nitrogen Dioxide Standard. Discussion Draft
prepared for EPA; SRI International, December 1977.
16. Trijonis, John, Empirical Relationships Between Atmospheric
NO., and its Precursors, EPA, Research Triangle Park, North
Carolina, February 1978.
17. Health Effects for Short-Term Exposure to Nitrogen Dioxide,
Final Draft, March 31, 1978, U.S. EPA.
18. Mobile Source Emission Factors, Final Document, EPA-400/9-
78-005, USEDA, Washington, D.C., March 1978.
19. U.S. EPA, "Status and Implications of Analyses of Ambient
N02 and Other Air Quality Data" (Draft), EPA, OAQPS, MDAD,
Research Triangle Park, N.C., May 26, 1978.
-------
SHORT-TERM N02 STANDARDS
VOLUME II
ESTIMATED COST OF MEETING
ALTERNATIVE STANDARDS
DRAFT REPORT
DRAFT**-
DO NOT QUOTE OR CITE
Submitted to:
Office of Air Quality Planning and Standards
Environmental Protection Agency
Reserach Triangle Park, North Carolina 27711
Submitted by:
Dale L. Keyes, Bharat Kumar, Robert D. Coleman
and Robert 0. Reid
Energy and Environmental Analysis, Inc.
1111 North 19th Street, 6th Floor
Arlington, Virginia 22209
December 26, 1978
-------
STATEMENT
This Draft Report is furnished to the Environmental Pro-
tection Agency by Energy and Environmental Analysis, Inc.
(EEA), Arlington, Virginia. The contents of the report are
reproduced herein as received from the contractor. The opin-
ions, findings, and conclusions expressed are those of the
authors' and not necessarily those of the Environmental Pro-
tection Agency.
-------
TABLE OF CONTENTS
Title , Page
A. Introduction and Caveats 1"
B. Air Quality Assessment Methodology 4
1. Point Source Modelling 5
2. Area Source Modelling 17
C. Air Quality Modelling Results 24
1. Point Source Analysis..... 24
2. Area Source Analysis 29
3. Point and Area Source Analyses Together 29
D. Control Options and Cost Analysis 34
1. Point Source Control Options and
Unit Costs , 34
2. Point Source Cost Analysis Procedure 44
3. Point Source Control Costs 45
4. Impact of Growth on Point Source
Control Costs 47
5. Area Source Control Options and Costs 52
6. Area Source Costing Procedure and
Results 56
E. Comparison of the Nationwide Cost Analysis With
the Chicago Case Study. . 60
F. Economic Impact 61
1. General Comments .• , 61
2. Point Sources 64
3. Area Sources 66
G. Summary and Conclusions 5-7
-------
VOLUME II
ESTIMATED COST OF MEETING ALTERNATIVE
SHORT-TERM K02 STAWDARDS
A. Introduction and Caveats '
This study is the second volume of a three-volume report
which attempts to identify the causes of high short-term
concentrations of nitrogen dioxide (NO-) and the additional
cost of controlling sources of nitrogen oxides•(NO ) emissions
X
to levels consistent with attainment of the ambient standards
under consideration (that is, the costs in addition to those
required to meet the Federal motor vehicle emission standards
and the NSPS's for stationary sources). Volume I focuses on
the mechanisms by which high ambient concentrations of N02 are
believed to occur. Volume II provides a preliminary assessment
of the sources which, through the mechanisms identified in
Volume I, might cause or contribute to high short-term (i.e.,
one-hour averaging period) concentrations of N02- Control
strategies are developed for these and used to estimate nation-
wide control costs. Volume III describes a detailed case
study of short-term 110- concentrations in Chicago. An area
source and multiple point source model was used to capture the
interactive effects of all NO emission sources in a region.
2C
The results shed light on the accuracy of the nationwide
study.
It should be emphasized at the outset that actual monitor-
ing data which could be used to estimate the expected contribution
of point sources are extremely sparse. Lacking those data, a
modelling technique based on a nonreactive Gaussian dispersion
model and empirical NO -to-NO_ conversion curves was used to
-1-
-------
estimate maximum ground-level concentrations of NOj.
Although it is believed that the results are reasonable, this
technique should be validated with data on observed ambient
NO- concentrations.
Any short-term study which attempts to assess the national
dimensions of what is, in effect, a multiplicity of localized
problems must necessarily impose simplifying assumptions on the
analysis. The most significant of these assumptions are de-
scribed below:
• Though ambient concentrations of N02 are
created by a mix of emissions from both
point and area sources, the two categories
of sources are treated separately in this
analysis. The area source analysis is
based on proportional ("rollback") modelling
of monitored air quality and estimated area
source emissions in urban areas. This is
a reasonable approach if, as appears true
from the available evidence, most monitors
in urban areas reflect contributions pri-
marily from area sources of NO emissions.
f±
Point sources are assessed by estimating
theoretical maximum contributions to
short-term N©2 levels with the dynamic
modelling technique noted above and de- -
scribed in Volume I. As noted, these
results are largely unverified by empiri-
cal observation.
• Interaction between point and area sources
is captured in a limited way by adding area
-2-
-------
source background concentrations to the es-
timated point source contribution. The high-
est annual average value recorded in an AQCR
is used to estimate the area source back-
ground for all point sources located in that
AQCR. Based on the results of the Chicago
case study, a background value SOper^gjat,
higher than the highest observed annual
average is used to represent area source
contributions to ambient N0_ levels under
conditions which maximize area and point
source interaction.
The need to verify our N02 modelling
technique has already been noted. Alterna-
tive approaches for representing the secondary
(derived) nature of N02 have also been dis-
cussed. Cole suggests setting maximum NO-
equal to the ambient 0, level plus 0.1 times
I/
the NO level. ' This appears to work well
jf*
for summer conditions, but should underesti-
mate N02 under conditions of low 0, concen-
trations characteristic of winter. In addi-
tion, empirical analyses of relationships
between N02 and its precursors suggest only
limited correspondence between levels of N0_
2/
and 0.,. ' However, this approach is used
here for comparison purposes.
Plumes from individual point sources are
assumed to be non-interactive. This is a
reasonable assumption for sources separated
by tens of kilometers, dependent, of course,
-3-
-------
on stack height. Unfortunately/ time limi-
tations did not allow an interactive analysis
for sources where this assumption does not
hold. This leads to some underestimation of
control costs, though in combination with
the following simplification, the degree of
underestimation may be small.
• Ambient levels due to NO emissions from
Jt
multiple stacks in single plants are assum-
ed to be additive. This is the same as
assuming that the points of maximum ambient
impact from every source have the same loca-
tion, irrespective of differences in stack
and emission characteristics. Ambient levels
and control costs are consequently overesti-
mated. However, the Chicago results show that
the overestimation in this case tends to balance
the underestimation introduced by the previous
assumption.
• The point source modelling assumes every
source is located in flat terrain; where
this does not hold, ambient concentrations
may be underestimated.
B. Air Quality Assessment Methodology
Since both point and area sources emit NO , an assessment of
X
the causes of high short-term NO- concentrations must consider
each type of source and. their respective concentrations. Studies
have shown that either can lead to relatively high concentrations.
However, the nature of their impacts are different. Point sources
tend to produce infrequent and spatially confined NO- peaks,
though the slow formation rate of NO- smooths out these "hot
spots" to some extent. Area sources, on the other hand, are lass
-4-
-------
varied in their impact on peak NO- levels in both time and
space.
Due to the placement of NO- monitors in urban areas and to
the relatively small variation in recorded levels over time
(for continuous monitors), a case is built in Volume I for the
use of monitoring data in assessing area source contributions
to NO- problems. The impact of point sources, however, can
only be captured through dispersion modelling exercises, given
the nature of existing monitoring networks.
The following sections of the report discuss the separate
treatment of point and area sources. The results of the two
analyses are then brought together in a final discussion and
assessment.
1. Point Source Modelling
a. General Approach
Detailed multiple source modelling of each AQCR was far
too ambitious for a nationwide study. Instead, each source of
NO emissions in EPA's NEDS file of jpoint sources was modelled
individually with a single source dispersion model. This
approach may be adequate for isolated sources, but for urban
areas, a means was needed to assess the interaction of multiple
point sources and the degree to which area source emissions
exacerbate point source problems. To assist in this regard, a
separate, detailed study of a single AQCR was undertaken. The
results of this case study can then be used to judge the
adequacy of the nationwide assessment.
The NEDS modelling analysis was initiated by specifying
model plants which ranged in size and operating parameters corres-
ponding to combustion processes in various source categories (e.g.
utility boilers, industrial boilers, and furnaces). The model
-5-
-------
plants were analyzed individually using a simple Gaussian dif-
fusion model (PTMAX) to assess the meteorological conditions
associated with ground-level maximum N02. These conditions
were then used with a simplified version of PTMAX to model the
air quality impacts of all NO sources in the NEDS file. Once
J^
the concentrations of NO around each point source had been
X
characterized by the diffusion'model, two alternative approaches
were employed to translate NOX into N02- Emission control
methods and their associated costs were then estimated for each
source.
The case study involved a detailed analysis of the multiple
point and area source contributions to peak short-term NO-
concentrations in the Chicago region. An EPA-approved point
and area source interactive model, RAM, was used for this
analysis. A detailed point and area source emission inventory
combined with the versatility of RAM provided a unique character-
ization of NO- concentrations in a large urban area. The
reasons for selecting Chicago as the case study AQCR and details
of the study are described in Volume III of this report. The
results of the Chicago case study provide both a sensitivity
check on the assumptions used in the nationwide study, and a
means of gauging the degree of over- or under-estimation of
control cost impacts.
It is important to re-emphasize that the nationwide point
source analysis focused on achieving alternative short-tern H02
standards through point source controls alone. Area source
emissions were treated as a background influence. Results of
the Chicago study were extrapolated to estimate the area source
contributions in each AQCR.
b. Processing of Point Source Emissions Data
Samples of raw data were retrieved from the NEDS point
source sub-file to determine the extent of erroneous and missing
-6-
-------
information. Upper and lower limits and default values for the
stack height, temperature, air flow rate, hours of operation,
and fuel heating values were established for each source category
based on standard operating practice and soibstituted for erroneous
or missing data in the file. These are shown in Table 1.
Default values for flow were calculated for each type of fuel
at the excess air rate normally associated with it. For combus-
tors fired with dual fuels, estimates were made assuming 100
percent firing of the fuel which had the highest emission rate.
The most recent emission factors from the Control Techniques
3 / • 4 /
Document ' , California Air Resources Board ARE 2-1471 Report '
5/
and AP-42 (Third Edition) ' were used for this analysis. Data
on the emission factors for industrial combustion processes are
limited. The variability in the emissions with fuel.type is
not as significant as it is among processes in the same fuel
category. The emissions factors used for industrial combustion
processes are, therefore, average values applicable to the
greatest number of processes in a fuel category. Revised emission
factors for cyclone boilers, which are significantly lower than
'those listed in AP-42, have recently been reported by Aerothern
and were used in this analysis . For example, the revised
emission factor for coal-fired cyclone boilers is 1.3 Ibs.
NOx/MM]
AP-42.
NO /MMBtu, approximately 60 percent of the value reported in
X
Emissions were calculated for operation at full load. In
the absence of information on rated capacity or maximum operating
rate, the hourly heat input rate was calculated using the
annual fuel consumption and the hours of operation.
All existing nitric.acid plants were assumed to meet the
5.5 Ib. IJ02/ton nitric acid regulation applicable to old sources.
-7-
-------
TABLE 1
DEFAULT VALUES
Source
Boiler
Acceptable range
Default
Stack
Temperature
320 < T <800
410
Stack Height
(m)
10 £ H £ 500
30
Hours of
Operation
0 < hours < 8736
5400
i
00
i
Internal Combustion
Acceptable range
Default
Chemical Processes
Acceptable range
Default
Petroleum Industry
Acceptable range
Default
320 < T i 800
410
290 < T £900
13 500
320 £ T £1100
500
5 £ II < 500
20
5 i II £ 500
15
5 £ II £ 500
15
0 < hours £ 8736
5400
0 < hours £8736
8000
O < hours<8736
8000
In-Process Fuel
Acceptable range
Default
Incinerators
Acceptable range
Default
310 £ T£l300
500
310 < T£1100
370
5 < II £ 500
15
0 £ H £ 500
15
0 < hours £8736
8000
0 < hours Is 6736
8000
SOURCE: EEA, Inc.
-------
This regulation is in effect in most states with nitric acid
plants.
c. Dispersion Modelling Methods and Assumptions
The Gaussian diffusion models used in these analyses are
non-reactive models. Maximum NO concentrations from the
Jt
single or multiple point sources were first estimated and then
translated to N02 levels using both of the approaches described
in Volume I of this study. The dynamic translation model de-
veloped by. EEA is the preferred approach for isolated point
sources.
For sources with multiple stacks and each stack serving
multiple combustors, diffusion calculations were made on a
stack basis. The maximum impact of all stacks in a source was
assumed to occur at the same point and to be additive—clearly
a conservative approach. Finally, the list of sources that
were estimated to violate.a 250 yg/m ambient N02 standard was
screened manually. Data -for sources with unusually high
estimated NO concentrations were reviewed, corrected if necessary,
J^
and ambient concentrations re-estimated.
d. Influence of Meteorological Conditions on Point
and Area Source Interaction
As noted earlier, meteorological conditions play a major
role in the short-term build-up of N02 concentrations from both
point and area sources of NO emissions. Meteorological condi-
Ji
tions, in addition to controlling the diffusion of N02, also
have a binding influence on its formation rate. A detailed
discussion of this subject is presented in Volumes I and III of
this report.
-9-
-------
A summary of the conclusions derived from the Chicago
case study is presented here. These results were used to select
the meteorological setting for the nationwide study.
• NO emissions from either point or area
Ji
sources can cause high short-term NO-
conclusions.
• Two distinct groups of point sources can be
identified in terms of their, response (dilu-
tion and N02 formation rate) to different
meteorological conditions: (1) plants with
tall stacks such as utilities, and (2) plants
with a large number of short stacks such as
steel mills and refineries.
• The diffusion characteristics of the second
point source group seem to be similar to
those of the area sources.
• The meteorological conditions that maximize
the impact of sources with high effective
stack heights are at an opposite extreme
from the conditions that result in high con-
centrations from area sources or point
sources with short effective stack heights.
• In the Chicago case study, an intermediate
set of meteorological conditions, closer to
those diffusion conditions which maximize
area source contributions, resulted in the
highest short-term HO, concentrations.
-10-
-------
The following summary of the test case analyses from the
Chicago case study should be helpful. The results of the point
and area source interactions under three different meteorologi-
cal conditions are presented in Table 2. The table shows the
receptors with the five highest estimated concentrations for
each set of meteorological conditions and the average concen-
tration at all receptors estimated to be above 200 yg/m .
This sensitivity analysis was performed on a portion of the
Chicago AQCR which included Cook, Dupage, and portions of Will,
Lake, and Porter Counties. As can be seen, total N02 concen-
trations are highest for the intermediate case. In addition,
the degree of point source control required is higher in the
intermediate case due to higher area source background concen-
trations than in the point source "worst case".
e. Selection of Scenarios
Since the point sources in NEDS include rural, isolated
sources as well as those located in dense urban areas, a single
set of meteorological conditions was deemed insufficient. For
sources in urban areas, as noted in the previous section,
the multiple point and area source influence is overriding. An
intermediate set of meteorological conditions would be more
appropriate for assessing the point source impact. But for
large point sources located in isolated areas, the "worst case"
for point sources alone is the appropriate choice.
Ideally, point sources in isolated areas should be
analyzed separately from those in urban areas. An attempt
at such an analysis was not made because of the large number of
sources and lack of information on their location. Instead, all
point sources were analyzed under the two sets of conditions.
Furthermore, the two alternative approaches for translating the
modelled NO from each point source into N09 were applied to
Jt £•
each set of meteorological scenarios. This produced four test
cases which are summarized in Table 3.
-11-
-------
TABLE 2
COMPARISON OF ESTIMATED NO LEVELS FROM POINT AND AREA SOURCES UNDER DIFFERENT
METEOROLOGICAL CONDITIONS IN CHICAGO3''
I
Receptors
with the
Five Highest Worst Case - Point
Concentrations Total Point
i 1 509 428
ft 2 589 409
* 3 348 209
# 4 348 225
* 5 342 219
Average of
all receptors
above 200
pg/m 277 165
Number of Receptors
Above 2OO |ig/in-* 47
Percentage of Power Plants
With Significant Contribu-
tions, i.e., Effective Stack
Height Less Than Mixing
Height 17
Source Worst Case - Area Source
Area Total .
81 568
81 479
139 472
123 472
123 472
111 371
Point
549
279
272
272
272
142
68
Area
19
200
200
200
200
199
Intermediate
Total Point
603 493
602 434
600 407
598 430
553 383
316 142
67
0 3
Chicago Case Study - Cook, Dupage, and portions of Will, Lake and Porter Counties.
The receptors used in the analysis were selected to record maximum total concentration.
receptors may reflect higher area source contributions, but lower total concentrations.
Case
Area
110
168
193
168
170
174
Other
UOURCE: EEA, Inc.
-------
TABLE 3
LIST OF CASES
Meteorological
Conditions
Translation
Approach
"Worst Case"
Point Source
Intermediate
Case
Wind Speed =
5.0 m/sec
Stability Class 3
Wind Speed =
1.5 m/sec
Stability Class
EEA's Rate Curves
Worst Case Point Source
Use of meteorological conditions maximizing the point
source influence alone implies that all sources are located in
isolated areas. Under these conditions, the impact of area
source contributions is estimated to be a minimum. This scenario,
therefore, results in an underestimation of the short-term prob-
lem for point sources in an urban area. The degree of control
required and the cost of control is lower. The selection of
meteorological parameters for this case is based on the model
plant analysis.
Intermediate Case
This scenario implicitly assumes that all point sources are
located in urban areas. The area source background is estimated
to be higher in this case than in the previous one. For sources
in isolated areas, this may overestimate the need for and cost
of controlling them to achieve a given ambient level.
(0.1 NO + O.J Translation Approach
X +j
The approach and its limitations are discussed in detail in
Volume I of this report. This approach assumes that, except for
the initial conversion of NO to NO- (about 10 percent), conver-
sion of NO is limited by the ambient levels of ozone.
EEA's Translation Curves
NO in each plume was translated into N02 concentrations as
a function of initial NO level in the plume and plume travel
time. A series of time-dependent curves relating NO to N0_ for
different initial N0x levels were developed based onxplume track-
ing studies. Details of the approach also are presented in
Volume I of this report.
-13-
-------
For a conservative (high side) estimate of the cost of im-
plementing point source control strategies to achieve a given
short-term standard, the intermediate meteorological case was
chosen. In addition, EEA believes that the translation curve ap-
*
proach is theoretically more valid. Thus, the final cost
and economic impact analysis was based on the results of Case
Four, while Cases One, Two, and Three were used to test the
sensitivity of the results to assumptions about meteorology
and the NO-to-NO- conversion process.
f. Area Source Contributions as M02 Background
Referring back to Table 2 (results of the Chicago case
study), one can see that the average area source concentrations in
each of the three cases are very close to the area source com-
ponents at the receptors with the highest total concentrations.
This implies a low spatial variation in the component of peak
NO- concentrations due to area sources. Some loss of spatial
variation in the area source concentrations could have, resulted
from limitations in the way RAM models area sources, and is ex-
plained in Volume III of this report. Regardless, observed am-
bient data jy a_regionwide level support the above conclusion.
The use of a regionwide average value to account for the area
source contribution at all receptors in an AQCR is therefore
reasonable.
As noted earlier, the short-term area source background in
an urban area varies with meteorological conditions. To quantify
the area source background level for the two sets of meteorological
conditions used in the national study, the average area source
concentrations for the same conditions in the Chicago study
* However, due to.the lack of readily available ambient NO-
data around point sources and to time constraints, the
translation curve approach could not be properly calibrated.
-14-
-------
were first related to the highest observed annual average
N0_ concentration in the Chicago AQCR.* Table 4 shows a
comparison of the estimated average one-hour area source
concentration and the highest observed annual average con-
centration in the Chicago AQCR. For the first case, maximiz-
ing the point source impact, the average estimated one-hour
NO- level from area source NO emissions alone is almost
£» H
equal to the highest observed annual average value at any
monitor; for the intermediate case, the estimated area
source background is higher by about 50 percent.
Assuming Chicago to be a reasonable representation of
area source problems in other AQCR's in the country, these
findings were used to estimate area source background levels
upon which point source contributions are superimposed. The
highest observed annual average ND.- in an AQCR was used for
the area source background in Cases One and Three, and 1.5
times the highest annual average for Cases Two and Four.
These background values were used uniformly across each AQCR
for all point sources irrespective of their actual location.
g. Changes in Point and Area Source Emissions
Growth in point sources was not, considered explicitly
in the analysis for two reasons. First, the new source
performance standards for NO are sufficient to prevent any
A,
new source affected from violating the most stringent ambient
standard considered. Secondly, though clusters of new
sources or expansions at existing sites may combine to
create a violation, the modelling approach used does not
consider multiple point source interactions.
*Studies have shown that the annual average NO- concentrations
in urban areas are mainly due to area source influence and
are relatively less sensitive to point source impacts.
Use of observed annual average concentrations to quantify the
area source influence is therefore reasonable. (See Volume I)
-15-
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TABLE 4
COMPARISON OF ESTIMATED AVERAGE ONE-HOUR N02
CONCENTRATION DUE TO AREA SOURCES ALONE (FOR ALL MODELED
RECEPTORS) WITH THE HIGHEST OBSERVED ANNUAL AVERAGE
IN THE CHICAGO AQCR
(ug/m3)
Case
Worst Case
Point
Source
Estimated
One-Hour
Average N02
111
a/
Highest
Observed
Annual NO.
b/
109
Ratio
1.0
Intermediate
Case
174
109
1.5
a' Average area source contribution for all receptors above
. j
b/
200 yg/ra . (Data from Table 2.)
1975 annual average values at the Chicago Camp Station.
SOURCE: EEA, Inc.
-16-
-------
(^
Changes in area source emissions were considered indi^ctly.
A 20 percent reduction in area source ambient background levels
would be expected in 1982 assuming a 1.0 percent annual increase
in travel and a 30 percent decrease in composite mobile source
emission factors due to new exhaust standards, no increase in
stationary area source emissions, and an average ratio of
mobile to stationary area source emissions of 3:1. In 1990, the
reduction would be about 35 percent. For the high growth
scenario (i.e., 3.0 percent increase in travel per year and a
1.0 percent increase in stationary area source emissions) , the
reductions in area source background levels are 10 percent
in 1982 and 16 percent in 1990.
2. Area Source Modelling
a. General Approach
The point source analysis represents a situation where the
total NO- concentrations from the combined impacts of point and
area sources are at a maximum. The meteorological conditions in
this situation tend to maximize the point source influence more
than that of the area sources. Therefore, the orientation in
the point source analysis is toward point sources as the cause
of, and the sole means to prevent, violations of a short-term
standard. However, there are other meteorological situations
under which the area source impact is enhanced to a level where
they alone may cause a violation of an NO- standard.
As one way to capture the maximum impact of area source
emissions directly, a simple rollback modelling analysis was
made of monitored NO- concentrations and current NO emission
-17-
-------
levels in those AQCR's which may experience future short-term
problems.* As noted in Volume- I. the monitoring jietworks in.
most AQCR's are believed to reflect 'the impact of area, as op-
posed to point, source emissions. Annual average concentrations
tend to show relatively little variation among stations, and
most continuous monitors show peak (second highest hourly
values) to mean (annual average) ratios of 6:1 or less. Using
ambient air quality data to analyze short-term NO- pollution
from area sources would thus appear reasonable. However, where
point sources do contribute significantly to peak NO- levels at
monitors which would qualify under the above definition as area
source-dominated, the burden of meeting a short-term NO-
standard would fall on both point and area sources. To the
extent that point sources may be more amenable to control, the
area source control requirements estimated by this method would
be overstated.
b. Model Description
Rollback is based on a simple proportional relationship
between emissions and ambient air quality:
Allowable NO _ N02 standard x 1975 NO Emissions
Emissions
No background NO,, level was assumed in the analysis since the
over al 1 approach^ (i.e., totally ignoring point sources) may
somewhat overstate the need for area source controls.
The basic procedure involved calculating allowable emission
levels for each AQCR and comparing them to current and future
emission levels. The percent control needed to meet the standard
was then obtained directly from these estimates.
*A totally comparable approach to the point source assessment
would be based on area source dispersion modelling in every
AQCR. However, this is impossible without detailed knowledge
of the spatial variations in area source emission levels with-
in each AQCR. Even if this were possible, dispersion model-
ling may not capture the worst case impact of area source
emissions due to the generalization of emission levels over
space (i.e., the spreading of emission evenly over a geo-
graphic area).
-18-
-------
c. Current Air Quality and Emissions
The sample of AQCR's on which the analysis is based, in-
cludes all those estimated by SR1/X to have current one-hour
NO,, concentscrtirons above 200 yg/m . These include 150 out of
a possible^ 243.AQCR's. The area source emission patterns for
these AQCR's are shown in Table 5. In over three-fourths of
the sample, area sources account for at least 50 percent of
all NO emissions. Highway vehicles vary appreciably in their
X
contribution, but in most regions, the emissions are above 20
percent (and in over one-fourth, above 50 percent) of total
NO loadings. External combustion sources (residential,
X
commercial, and institutional space heating; space and process
heating in small industrial plants) comprise the other major
category, but are much less important. The remaining area
sources are solid waste incineration, internal combustion
engines (e.g., gas turbines used to generate electricity), the
residual mobile sources (off-highway vehicles), and miscellaneous
sources such as forest fires.
Base year one-hour ambient N02 concentrations for each
AQCR were set equal to the higher of (a) the second highest
hourly concentrations recorded for all continuous monitors
with peak to mean ratios of 6:1 or less; or (b) six times the
highest annual average for any 24-hour monitor in the AQCR.
This procedure was designed to eliminate point source influences
while capturing the worst area source N02 problem in each
AQCR.
d. Change in Emissions and Impact on Attainment
Those AQCR's which currently would be unable to attain
one of the short-term NO- standards under consideration could
only achieve it at some future point if controls placed on
area sources brought sufficient net reductions in NO emissions.
Jv
Conversely, growth within those AQCR's which currently attain the
-19-
-------
TABLE 5
ABE*. SCOHC5S TO TOTAL
TSZ AQSl'l
(1975)
LQAD33IG
BtiMlOM Of HO,
(P«rc«nt Contribution To Total Eaisaions)
AOC*
Ito.
2
3
4
f
7
12
13
14
IS
17
18
19
20
21
22
24
25
28
29
30
31
33
36
38
' 41
42
43
44
45
46
47
49
SO
52
53
54
55
56
58
59
64
65
uii
67
08
69
70
71
72
73
«/
Total
ATM
_ 3oure««
99
100
46
54
86
52
20
28
77
99
SO
51
71
97
55
75
63
95
77
30
75
18
6S
43
78
74
$1
94 •
56
S3
71
48
51
SO
56
45
48
65
39
78
95
18
7U
$0
39
35
32
52
12
65
Thas* an csa
one-hour NO? t
external
Coofiuseion
Area Sourest
08
07
04
06
04
04 "
01
02
07
14
02
07
07
11
OS
07
04
OS
06
07
OS
01
06
03
07
12
14
08
08
03
07
01
01
01
03
02
02
04
02
03
09
02
06
08
03
03
03
04
01
07
AQOt's which !I»VB
sanontrationa com
Light Ouey
Highway
Vehicles
46
S2
21
2S
4S
30
13
IS
41
39
23
22
30
43
27
37
36
56
43
42
41
11
31
20
54
45
31-
66
26
19
t
41
23
23
29
32
24
27
33
20
45
34
08
37
22
IS
IS
17
26
OS
30
Kaavy Duty
Highway
Vahiclea
20
19
09
09
16
17
04
04
13
20
10
07
11
14
07
11
09
14
12
14
U
02
12
08
08
08
07
10
11
20
10
09
09
09
09
08
08
11
07
12
16
02
08
08
07
06
06
95
02
09
SOURCE; iPA's NEDS file, January 9. 1978.access.
-20-
-------
TRBLE 5 (Continued).
Emissions of N0x
(Percent Contribution of Total Emissions)
Total External Light Duty Heavy Duty
AOCR Area Combustion Highway Highway
Mo. Sources Area' Sources vehicles Vehicles
74 69 04 37 08
75 22 02 11 03
76 81 09 40 16
77 25 02 11 04
78 27 03 12 OS
79 40 03 21 07
80 67 08 31 14
81 96 13 44 18
82 57 07 29 10
83 38 04 19 07
84 36 04 18 07
85 50 06 19 12
92 68 OS 30 14
94 17 02 07 04
95 S3 03 19 IS
98 37 02 IS 07
99 66 OS 26 14
101 94 04 SI 18
102 56 04 28 09
103 24 03 10 03
10S 63 04 29 . ' 10
106 28 02 10 04
107 55 OS 32 09
109 SO OS 32 09
112 69 03 45 09
113 64 03 41 09
114 71 04 - 46 09
US 56 04 33 08
116 26 01 IS 03
117 80 20 43 09
118 83 23 43 09
119 68 18 33 08
120 63 11 36 08
121 61 10 37 08
122 58 OS 34 08
123 60 07 34 09
124 28 03 15 04
125 77 07 44 11
127 94 07 47 14
128 79 06 37 12
129 69 02 15 07
130 92 12 33 18
131 58 09 26 10
136 59 03 30 13
144 75 18 21 10
145 62 06 22 15
149 ' 88 11 56 11
151 67 09 34 12
152 65 - 08 25 11
153 78 OS 35 13
-21-
-------
TA3UL5 (Continuari)
SaiMiOM of NO^
(Pcrcmc Contribution of Tot»l R«i»»iong)
Bxc«rn*l Light Duty HMvy Oaty
Coototwcioa Higtnwy Highway
Ar»« Soure«« veh'ieiaa Vchiei«»
155 SI 03 27 10
15» 57 Ot 35 Ot
1*0 38 OS 24 04
1(1 SO OC 32 OS
112 CO 12 34 06
165 37 02 17 07
144 SI 03 28 12
167 49 02 29 10
16» 79 02 20 09
1«» 17 03 40 IB
171 S9 02 21 25
173 73 06 41 11
174 58 06 31 09
175 96 07 S3 13
176 91 08 49 14
178 36 07 29 09
180 94 07 52 13
111 10 .01 05 01
182 64 03 38 " 09
1*3 22 02 12 03
184 80 OS 37 25
188 SI 03 20 16
1»9 59 02 22 18
193 76 07 37 18
193 64 09 37 41
196 38 05 19 07
197 29 04 14 05
198 82 03 47 12
199 36 02 19 06
200 42 - 02 22 06
201 65 01 37 09
202 76 02 48 11
203 82 03 48 12
208 40 0 22 07
311 38 02 18 05
212 55 02 27 06
214 13 0 05 01
215 79 07 24 27
21« 41 OS •• 16 05
217 7b OS 32 10
218 19 0 09 03
220 70 • 16 20 10
223 58 03 30 09
225 41 03 23 07
226 "S3 03 32 08
22' S6 OS 28 09
234 20 Q8 08 02
237 44 o 20 07
239 «2 07 28 11
243 48 06 13 06
-22-
-------
standard could outweigh emission reductions achieved by con-
trols and thus lead to future violations. Projections of
future attainment status are consequently sensitive to the
assumed growth rates for emission sources and the assumed
effectiveness of emission controls.
Time trends in emissions were projected separately for
stationary and mobile sources. Population growth is the
logical driving force for growth in emissions from many station-
ary area sources. Based on a projected annual population
8/
growth rate of 0.9 percent for the entire nation, a 1.0
percent growth rate was set as the upper bound for increases
in stationary area source emissions. Of course, some area
sources such as solid waste incineration are not expected to
grow at all and could, in fact, u..*/ decrease over time. Con-
sequently, an annual growth rate of zero was set as the lower
bound. For both growth scenarios, no additional NO emissions
J^
control was assumed.
A national growth rate for mobile sources (light and
heavy duty highway vehicles) of between two and three percent
per year in vehicle miles travelled (VMT) is a reasonable
~~ */9/)
expectation.\j/ However, due to monitor location and the
dispersal and transformation characteristics of NO , recorded
X
peak N02 concentrations may be most responsive to emissions
from vehicles on the most heavily travelled roads. VMT growth
rates for these highways (and thus, the effective growth
rates) may be much lower than growth in total VMT. We used
rates of 1.0 and 3.0 in order to bracket this average and thus
test the sensitivity of the results to this assumption. With
an increase in VMT per year comes a concomitant decrease in
emission rate (gm/VMT) as new vehicles meet the increasingly
stringent Federal emission standards and, over time, become a
larger fraction of the vehicle fleet. Composite emission
factors for a weighted national average of all highway vehicles
-23-
-------
were provided by EPA for each year between 1975 and 1990. '
The fractional reductions in emission rates were thus combined
with the fractional increase in VMT to obtain changes in
emissions between the years 1975 and 1982, and 1975 and 1990.
Table 6 Summarizes the results. Improvements in emission
controls as mandated by the 1977 Amendments to the Clean Air
Act are seen to bring significant overall reductions between
now and 1990. However, examination of the emission changes on
a yearly basis reveals that the lowest emission level occurs
in 1989 (for an annual VMT rate of 3.0 percent) and the level
turns upward in response to increases in VMT thereafter.
The nationwide fractional changes in stationary and mobile
rea source emissions were then applied uniformly to all
AQCR's. Implicit in this procedure is the assumption that the
composition of area sources within the stationary and mobile
categories is everywhere the same. This is obviously incorrect,
but is reasonable when applied in the framework of an initial
assessment and when compared to the approximate nature of the
ambient air quality estimation procedure.
C. Air Quality Modelling Results
1. Point Source Analysis
Table 7 presents the results of the modelling analysis in
terms of the following:
• Numbers of point sources requiring control
and the combustors or process facilities (i.e.,
SCC's) associated with these point sources.
• The number of AQCR's in which these facili-
ties are located.
-24.
-------
TABLE 6
FRACTIONAL CHANGE IN MOBILE SOURCE EMISSIONS OVER TIME
Composite Emission Factor'
(gm/VMT)
a/
1975
4.64
1982
3.25
1990
2.15
Ratio of Emission Factor to
1975 Emission Factor
1.00
.70
.463
Ratio of VMT to 1975 VMT
• 1.0% annual growth
• 3.0% annual growth
1.00
1.00
1.07
1.23
1.16
1.56
Ratio of Emissions to 1975
Emissions*3^
• 1.0% annual VMT growth
• 3.0% annual VMT growth
1.00
1.00
.749
..862
.538
.723
a/
b/
Composite emission factors are based on the current level of Federal
tailpipe emission standards, the estimated age distribution of the
vehicle stock, the estimated national distribution of vehicle types
(weighted by annual VMT), and assumed deterioration in emission
controls. (These values were provided by EPA.)
Computed by multiplying together values in the second-and third rows.
SOURCE: EEA, Inc.
-25-
-------
TABLE 7
POINT SOURCE MODELLING RESULTS
(1975 Conditions)
Translation
Approach
Ambient Standard
yg/m
One -Hour Average
Case 1
Case 2
EEA ' s Rate Curves
Case 3
Case 4
• • Point Sources Required to Control
1000
750
500
250
9
25
53
732
1000
750
500
250
183
377
641
5330
6
19
66
638
1
3
10
101
18
35
79
408
SCC's Requiring Control
103
314
705
4774
10
65
284
1185
324
636
1113
4069
AQCR's in Violation
1000
750
500
250
4
6
14
144
4
7
18
143
1
3
6.
39
6
11
30
119
a/
0 levels are the 1975 second high hourly values in each AQCR.
Cases 1 and 3: Meteorological conditions correspond to maximization
of point source influences. (Area source background =
highest observed annual NO. average at any monitor
in each AQCR.)
Cases 2 and 4: Intermediate meteorological conditions. (Area source
background » 1.5 x highest observed annual NO. average
in each AQCR.)
See Table 3 for a further description of the four cases.
SOURCE; EEA, Inc.
-26-
-------
The cases refer to the matrix presented in Table 3. For
Cases One and Two, where the (.1 NO + OO approach was used,
H *J
the results are similar. The ozone limiting component is a
major portion of the N0_ concentration and is unaffected by
the change in meteorological conditions. Higher NO levels
a
in Case One (due to higher wind speed) over-compensate for the
low background level used in this scenario and result in
overall higher concentrations than in Case Two.
Use of the translation curve approach showed a larger
variation in the control requirements. Ground-level NO-
concentrations are much higher in Case Four (intermediate
meteorological conditions) than that in Case Three (worst
case-point source conditions). This is consistent with the
results of the Chicago case study described previously. A
much higher degree of point source control is thus required in
Case Four. The number of AQCR's with modeled receptors showing
one or more violations (before point source control) of a 250
yg/m
Three.
yg/m standard is 119 for Case Four, as opposed to 39 for Case
For the final cost and economic impact analysis, only
those point sources estimated to cause violations of the 250
and 500 yg/m standard in Case Four were considered.
The estimated number of AQCR's not attaining the alternative
standards for Case Four and for each of two years is shown in
Table 8. These were calculated using the assumptions about
growth of area source emissions described in Section B.l.g.,
and summarized at the bottom of Table 8.
A total of 4,069 sources associated with 408 industries
located in about 119 AQCR's are estimated to be in violation
-27-
-------
TABLE 8
NUMBER OF AQCR'S NOT ATTAINING THE ALTERNATIVE
SHORT-TERM AMBIENT N02 STANDARDS BASED ON THE
POINT SOURCE ANALYSIS
One-Hour Standard ,
(yg/m j) Number of AQCR's in Violation '
1000
500
250
SOURCE: EEA, Inc.
' Changes over time are caused by changes in area source
emissions and thus ambient background levels. (Mobile
sources (i.e., travel) are assumed to increase by 3.0
percent per year, new vehicle emission factors correspond
to the Federal Motor Vehicle Control Program, and sta-
tionary area source emissions increase by 1.0 percent
per year.) Point source growth is not considered since
new sources considered individually should not lead to
violations.
-28-
-------
of a 250 yg/m standard in 1975. For the 500 yg/m standard,
the number of affected sources and AQCR's is reduced signifi-
cantly. Seventy-nine industries with about 1,113 processes and
approximately 30 AQCR's are estimated to be in violation of
the standard. A breakdown of the types of processes (source
classification codes—SCC's) and industries (standard indus-
trial classifications—SIC's) that are likely to contribute to
violations of the 250, 500, 700, or 1,000 yg/m standards is
shown in Tables 9 and 10.
2. Area Source Analysis
Table 11 summarizes the results of two growth scenarios
(low: 0 percent stationary and 1.0 percent mobile source
growth rate; high: 1.0 percent stationary source and 3.0
percent mobile source growth rate), assuming mobile source
emission standards will remain as currently mandated.
Except for the 250 yg/m standard, only a few AQCR's are
estimated to be in nonattainment status due to area source
emissions. For the 250 yg/m standard, the current Federal
motor vehicle control program is seen to effect a considerable
improvement in attainment status over time, though more
than 70 AQCR's may still experience violations in 1990.
3. Point and Area Source Analyses Together
Table 12 lists the number of AQCR's estimated to be in
nonattainment in either of the two analyses. (The data are
taken from Tables 8 and 11.) The two analyses represent two
separate air quality situations. As noted earlier, the point
source analysis is designed to reflect the maximum expected
ambient N02 levels due to the influence of both the point and
area sources together (though point sources predominate);
these levels are probably not captured by the existing monitor-
ing networks in most urban areas. However, the control of
-29-
-------
TABLE 9
TYPE OP SOURCES LIKELY TO EXCEED SPECIFIED
N02 LEVELS (CASE FOUR ANALYSIS)
NO., Levels (yg/m3)
Source Category
Utility Boilers - Coal
Utility Boilers - Oil
and Gas
Industrial Boilers -
Coal
Industrial Boilers -
Oil and Gas
Gas Turbines
Reciprocating 1C Engines
Industrial-Combustion
Processes
Nitric Acid
Municipal and Industrial
Incinerators
250
350
599
300
742
268
698
1,045
61
11
500
42
7
72
207
19
516
235
19
1
750
15
0
10
108
10 -
376
114
3
0
1000
0
0
0
21
5
278
17
3
0
TOTAL 4,069 1,113 636 324
-30-
-------
TABLE 10
TYPE OF INDUSTRIES LIKELY TO EXCEED SPECIFIED ONE-HOUR N02 LEVELS
(CASE FOUR ANALYSIS)^
NO., Levels (ug/m3)
Utility
Boilers
Internal Combustion - Reciprocating
Industrial - In Process Fuel Use
Gas & Oil Pipe Lines (I.e. Engines)
Refineries
Steel
Metal Melting
Asphalt
Lime Kiln
Glass
Cement
Food
Automotive
Waste Water Treatment
^Miscellaneous
Non-Combustion
Chemical
(Nitric Acid, etc.)
Total
250
136
26
48
37
23
15
10
4
4
3
4
4
3
67
24
408
500
6
14
33
8
5
' 2
1
0
-
-
-
-
-
10
6
79
750
2
7
17
5
2
0
0
-
-
-
-
-
-
-
1
34
1000
0
4
9
3
0
0
0
-
-
-
-
-
-
-
1
17
-31-
-------
TABLE 11 ,
CHANGES IN AREA SOURCE EMISSIONS FOR 150 AQCR's AND AQCR ATTAINMENT STATUS FOR ALTERNATIVE
GROWTH RATES AND ONE-HOUR NO2 STANDARDS3/
Area Source Emissions Summed
For All 150 AQCR's
(tons x 106/year)
1975
1982
High
Growth
b/
Low
Growthb/
1990
High
Growth
Low
Growth
i
Ol
• Mobile Sources
• Stationary
Total
Number of AQCR's Not
Attaining the Standard
• lOpQ yg/m
• 750 pg/m3
• 500 pg/m
• 250 ug/m
6.3
3.2
9.5
"""p""
2
17
94
5.6 4.9
3.4 3.2
9.0 '8.1
0 0
2 0
10 4
84 68
4.9
3.7
8.6
0
0
7
73
3.6
3.2
6.8
0
0
2
45
a/
b/
Based on 150 AQCR's recording (or estimated to exhibit) second highest one-hour NO_ levels of
200 |ig/m3 or more in 1975.
"Low growth" assumes a 1.0 percent annual growth rate for VMT and a zero percent annual growth
rate for stationary area sources. "High growth" assumes a 3.0 and 1.0 percent annual growth rate
for VMT and stationary area sources, respectively. Statutory mobile source emission standards
are also assumed.
-------
OJ
I
TABLE 12
NUMBER OF AQCR'S ESTIMATED TO BE IN NONATTAINMENT IN BOTH THE AREA
AND POINT SOURCE ANALYSES (NO ADDITIONAL SOURCE CONTROLS ASSUMED) a//
One-Hour Standard
One-Hour Standard ' Number of AQCR'S in Violation
): 1975 1982 1990
1000 666
500 45 36 29
250 158 145 133
' High area source growth assumed: 3.0 percent increase in travel and 1.0 percent
increase in stationary area source emissions.
-------
point sources alone does not assure attainment of the various
standards under all meteorological conditions in all AQCR ' s ,
though control of point sources alone is estimated to attain
the standards under the conditions used in the point source
- s
analysis. Under certain other extreme meteorological conditions,
the area source impact alone (even though not as severe as the
combined point and area source impacts) may exceed one or more
of the various standards. The area source analysis attempts to
capture this possibility. Thus, the two together provide a basis
for estimating the number of AQCR's in nonattainment under all
conditions.
It would appear that about 160 AQCR's would currently
ate a 250 ya/m standard and about 45 would violate a 500
standard if sufficient monitors were available to record
them. By 1990, without additional emission controls, the' num-
bers would decline to 133 and 29, respectively.
D. Control Options and Cost Analysis
1. Point Source Control Options and Unit Costs
Each plant identified as having a potential to exceed any
of the alternative standards was analyzed to determine the
percent reduction required to reach each level with the types
of control available. Tables 13 through 19 show the kinds of
control available for each source type. Controls and efficien-
cies are taken from EPA's. control techniques document for nitro
gen oxides. These tables also show the date of availability,
capital and annual costs (expressed as $/MMBtu) , and the
effect on fuel consumption. (Annualized costs are in 1976
dollars and assume a capital recovery factor of 16 percent.)
-34-
-------
TABLE 13
1 I '
COST AND EFFECTIVENESS OF NOX CONTROLS FOR UTILITY BOILERS - COAL-FIRED
Differential Control Costs
Ol
01
I
Control Techniques*'
LEA
LEA + OSC
Retrofit: Low
NOX Burner
Retrofit: Dry
SCR (only NOX)
Control
Potential
11%
22%
40%
90%
Earliest
Year
Available
Present
Present
1980
1985
Initial Investment
(102$/106Btu/hr.)
0.60
1.25
2.00
60.00
Annual
Costc
(f/106Btu)b/
0.2
0.5
0.8
26.0
Effect On
Fuel
Consumption
.5% Decrease
0.5% Increase
0
3.0% Increase
'
a/
'LEA = Low Excess Air
OSC = Off-Stoichiometric Combustion
SCR => Selective Catalytic Reduction
Annual Cost = Initial investment annualized at 16 percent plus operation and maintenance costs.
6 4
14/10 Btu annual heat input = 0.54 $/kW 8 5,400 hours of operation and 8 10 Btu = 1 kWh.
= 0.1 nil/kW hr.
Nominal heating value of coal = 28 KJ/KG (12,000 Btu/lb).
SOURCE: Constructed from data in Reference 3
-------
TABLE 14
COST AND EFFECTIVENESS OP NOX CONTROLS FOR UTILITY BOILERS - GAS- 4 OIL-FIRED
Differential Control Costs
Ol
I
a/
Control Techniques
LEA
LEA + OSC
LEA + OSC + FGR
LEA + OSC + Nil 3
Injection
Retrofit: Dry SCR
(NOX only)
Control
Potential
17%
40%
59%
70%
90%
Earliest
Year
Available
Present
Present
Present
1981
1982
Initial Investment
(102J/106Btu/hr.L
0.3
0.8
9.0
8.0
60.0
Annual
Cost
(f/106Btu)b/
Neg.
0.28
2.8
14.0
26.0
Effect On
Fuel
Consumption
0.5% Decrease
1% Increase
1% Increase
1% Increase
3% Increase
a/
FGR - Flue Gas Recirculation
SCR = Selective Catalytic Reduction
b/lf/106Dtu annual heat input « 0.54 $/kW for 5,400 hours of operation 9 10 Btu - 1 kH hr.
- 0.1 mil/kWh
SOURCE: Constructed from data in Reference 3
-------
TABLE 15
COST AND EFFECTIVENESS OP NOX CONTROLS FOR INDUSTRIAL BOILERS - COAL-FIRED
Differential Control Costs
Control Techniques
LEA
LEA + OSC
Retrofit: Low NOX
Burner
Retrofit: Dry SCR
(NOX Only)
Control
Potential
10%
20%
50%
90%
Earliest
Year
Available
Present
Present
1985
1985
Initial Investment
(102$/106Btu/hr.)
0.7
1.8
3.0
50.0
Annual
Cost •
0.29
0.66
1.10
23.0
Effect On
Fuel
Consumption
1% Decrease
1% Increase
0
3% Increase
a'l
-------
TABLE 16
COST AND EFFECTIVENESS OP NOX CONTROLS FOR INDUSTRIAL BOILERS - GAS- $ OIL-PIRED
Differential Control Costs
01
00
I
Control Techniques
l.liA
LCA + OSC
Retrofit: Low NOX
Burner
Flue Gas Treatment
Retrofit: Dry SCR
(NOX Only)
Control
Potential
10%
16%
Earliest
Year
Available
Present
Present
Initial Investment
(lo2|/l06Btu/hr.)
0.7
1.4
Annual
Cost
(»/106Btu)a/
0.26
0.6
Earliest
Fuel
Consumption
1% Decrease
1% Increase
50%
90%
1981
3.0
50.0
1.1
23.0
0
3% Increase
M/10 Dtu annual heat input »'0.1 mil/kW hour.
SOURCE: Constructed from data in Reference 3
-------
TABLE 17
COST AND EFFECTIVENESS OP NOX CONTROLS FOR GAS TURBINES AND 1C ENGINES
Control Techniques
Differential Control Costs
Earliest Annual
Control Year Initial Investment Cost
Potential Available (102|/106Btu/hr.) (j/106Btu)^
Effect On
Fuel
Consumption
Gas Turbines
CM
to
I
Water Injection
Engines
Fine Tuning Q
Changing A/P
Retrofit Dry SCR
60%
30%
90%
Present
Present
1985
12.5 ,
0
30.0
4.6
2.0
17.0
2% Increase
10% Increase
1% Increase
a/lf/106Btu = 0.1 mil/kWh 8 104Btu/l kWh.
SOURCE: Constructed from data in Reference 3,
-------
TABLE 18
COST AND EFFECTIVENESS OP NOX CONTROLS FOR INDUSTRIAL PROCESS FURNACES
Differential Control Costs
-k
Earliest
Annual Effect On
Control Year Initial Investment Cost Fuel
Control Techniques Potential Available (102$/106Btu/hr.)a/ (f/106Btu)V Consumption
l.liA 25% Present 1.03
LliA + FGR 40% Present 5.80
Advanced Design
Burner New Equipment/
Retrofit 50% 1981 3.00
Retrofit Dry SCR
(NOX Only) 90% 1985 .50.00
0.4 1% Decrease
1.9 1% Increase
1.1 0
20.0 2% Increase
al kWe = 10Btu/hr.
b/U/106Utu annual heat input -0.1 mil/kWh.
SOURCE: Constructed from data in Reference 3,
-------
TABLE 19
COST AND EFFECTIVENESS OF N0y CONTROLS FOR NITRIC ACID MANUFACTURING
Control Techniques
Earliest Differential Control Costs
Control Year Initial InvestmentAnnual Cost
Potential Available lp3|/Ton/daya/ I/Ton*/
Effect On
Fuel
Consumption
Chilled Absorption
90%
Present
2.0
2.0
0
a/ Darned on a model plant of 300 tons/day capacity operated for 8,000 hours per year,
SOURCE: Constructed from data in Reference 3.
-------
For each source category, up to five levels of control were
established:
• Low Excess Air (LEA)—Operation of the source
burner at close to theoretical air. This is
the easiest and least costly control techno-
logy and can provide a 10 to 17 percent re-
duction in uncontrolled NO emissions.
• Low Excess Air Plus Off Stoichiometric
Combustion (LEA & OSC)—This includes any
of a series of combustion modifications
which reduce peak flame temperature and
suppress NO formation. This technique is
J£
applicable to most source types, is imme-
diately available, and provides an estimated
20 to 40 percent reduction in NO emissions.
X
Flue Gas Hecirculation (FGR)—In addition to
LEA and OSC, FGR can be used to provide an •
extra 20 percent reduction in NO emissions
Jt
for cas- and oil-fired sources.
Advanced Burner Designs—Special burners
designed to operate at very low excess air
and use advanced combustion techniaues are
being developed by EPA and industry. If
these proarams are successful, they offer
about a 50 percent reduction in NO emis-
Ji
sions. For this study, it has been assumed
that the burners will be developed and will
-42-
-------
be available for new and existina sources.
Retrofit costs are assumed to be considerably
higher than new installations.
• Selective Catalytic Reduction (SCR)—The
reduction of ammonia and NO over a catalyst
X
can be used to reduce NO emissions by up to
X
90 percent. SCR systems are operating on several
laroe oil- and oas-fired boilers in Japan, but
have not yet been demonstrated on U.S. boilers.
In this study, it has been assumed that SCR
will be developed and available for use in
1982. Costs for SCR are taken from EPA studies
and ad-iusted to allow for retrofit (includina
installation of a flue gas heater).
The above control techniques were assumed to be applicable
to boilers and industrial furnaces. Specific techniques
such as water injection, fine tuning, and chilled absorption
were assumed for gas turbines, internal combustion engines,
and nitric acid plants.
Cost and effectiveness values for each control type are
reasonably well-established for boilers and process sources,
but limited investigation of NO reduction has been carried
X
out for furnaces such as cement kilns, petroleum heaters,
and glass melting furnaces. Based on the NO control techni-
3/ ll/
cues document / and communications with Aerotherm, ' we
have assumed that combustion modifications and FGR are as
effective for these sources as for boilers.
It should be noted that, due to time and data constraints.
all control costs are assumed to be linear with size (i.e.,
a constant cost per unit size regardless of capacitv). This
will introduce some error in the costing. The overall
-43-
-------
magnitude of the error introduced is not clear since the
linear assumption will tend to overstate some costs while
understating others.
2. Point Source Cost Analysis Procedure
Each plant identified as being capable of causing an
N02 concentration greater than one of the specified standards
was evaluated individually to determine the type of control
required and the cost and energy penalty of the control
technique. The procedure followed is outlined below:
• The maximum concentration from each source in
the plant (estimated by the dispersion model)
was summed to determine the total concentration
of N02. This concentration was then compared
.-to each of the specified standards (250 to 1,000
ug/m } to determine whether emission control was
needed.
• The type of control used by each source within
the plant to meet each alternative standard was
determined from the combination of controls at
all sources which would achieve required reductions
in ambient N02 at least cost. For each source,
each applicable control technology was considered.
Combinations of sources and technology were ranked
by annual cost of reducing the plant's air quality
by 1 yg/m . This measure ($/ug/m ) was used since
it combines the air quality impact of the source
with the cost of controlling its emissions. Con-
trol technologies were selected one by one, start-
ing with the lowest cost (highest cost-effective-
ness) option until the air quality goal was met.
-44-
-------
o After technologies were selected for each
source within a plant, the capital costs and
the effect on source and plant fuel consump-
tion were computed.
3. Point Source Control Costs
Control costs only for standards at 250 and 500 yg/m are
presented here. For levels above 500 yg/m , the costs were in-
significant. As noted in section B.l.e, a conservative but rea-
listic set of meteorological conditions and a theoretically more
justifiable approach used for estimating the NO- concentrations
form the basis for selecting case four for the final economic
impact analysis. But for the purpose of comparison, the capital
and annualized costs for all four cases are presented in Table
20.
The capital cost of point source control to meet a 250
yg/m standard could range anywhere from about 600 million
to over 3 billion dollars, depending on the estimation
approach. For the 500 yg/m standard, the capital cost is
reduced significantly, and ranges from 14 to 46 million
dollars. The annualized cost for both the 250 and 500
yg/m standards is significantly affected by the impact on
energy consumption. Frequent use of combustion modification
results in a net savings in the fuel cost in almost all cases.
The savings in some cases are substantial enough to completely
balance the annual cost of control. The use of more stringent
controls incurs an energy penalty. The variation in the fuel
impact among the different scenarios is dependent on the
severity of the air quality impact in each case and the level
to which individual sources have to be controlled.
-45-
-------
TABLE 20
POINT SOURCE CONTROL COSTS FOR DIFFERENT CASES
Case Number
and Description
CASE 1: Worst Case - Point
Source (low background)
.1 NO + 0
x 3
CASE 2: Intermediate Case
(high background)
.1 NO +0,
x 3
CASE 3: Worst Case - Point
Source (low background)
EEA's Translation Curves
CASE 4: Intermediate Case
(high background)
EEA's Translation Curves
250 |ig/m Standard
Capital Cost9/
(106 dollars)
3,073
2,169
589
1,496
Annual Cost"/
(106 dollars)
630
480
66
363
500 pg/m Standard
Capital Cost9/
(106 dollars)
37
14
4
46
Annual CoatP/
(106 dollars)
11
-1
-1
-1
a/ 1976 dollar basis.
b/ Annual Cost = capital cost annualized @ 16 percent + operation and maintenance cost based on capacity
and hours of operation + fuel penalty.
SOURCE: EEA, Inc.
-------
Table 21 lists further details of the Case Four analysis.
The plants and combustors shown are those which the costing
algorithm selected as being least costly to control. The
number of sources is smaller than shown in Table 8 because
not all sources within a plant have to be controlled in
order to achieve the necessary emission reduction.
Tables 22 and 23 show a breakdown by source type of
capital and annual costs (Case Four) for the 250 and 500
yg/m standards. Table 24 provides a legend for this table.
4. Impact of Growth on Point Source Control Costs
No attempt has been made at this point in the cost
analysis to account for the impact of changes in emissions
from point sources over time. As noted in the methodology
section, a proper treatment of growth would consider both
point and area sources and both emission-increasing and
emission-reducing factors. Factors which may lead to reduc-
tions in emission levels include increasingly stringent
emission requirements for mobile sources and the displacement
of fossil fuel by electricity for space heating purposes.
Both of these factors should lead to a decrease in NO
x
emissions from mobile and stationary area sources.
On the other hand, increases in electrical demand and a
shift to coal from oil and gas in major fuel burning installa-
tions, will lead to increased emissions from point sources.
(Emission factors for coal-fired equipment run two to four
times higher than gas-fired equipment, and one to two times
higher than oil.) In addition, the use of flue gas desulfuri-
zation may increase the ambient concentration of N02/ by
reducing flue gas temperature and thus plume rise. Since
the Clean Air Act Amendments of 1977 require that new fossil
fuel-fired stationary sources meet fixed emission removal
standards, FGD systems are likely to be employed in most
utility and industrial combustors constructed after 1980.
-47-
-------
TABLE 21
DETAILS OF POINT SOURCE OCMmOL COST /JJALYfIS FOR CASE POUR
NO Standard
(One-Hour Average)
ug/m3
500
250
Number of
Plants
Affected
79
408
Number of
Sources
Controlled
794
3,628
Approximate
Capital Costs
(106 dollars)
46
1,496
Approximate
Annual Cost
(106 dollars )b/
-1
363
Approximate
Fuel Penalty
(Barrels of
oil/day
Equivalent)0
-2,331
-4,096
00
I
a' Mostly combustors-.
Including fuel with coal assumed at $1.60/MMBtu and oil and gas at $2.60/MMBtu.
A negative sign indicates a fuel savings.
SOURCES: EEA, Inc.
-------
TABLE 22 - COST BY COMBUSTOR TYPE FOR ATTAINING A 500 yg/nf5 STANDARD
a/
Source Category 1
^
NUMBER OF USES 12
EMISSIONS REDUCED(G/S> 524.
INITIAL COST (1000'S*) 1826.
ANNUAL COST (1000'S*> -1776.
FUEL COST (10E+9BTU) -1329.
Source Category 2L , _
I.. -. 1
NUMBER OF USES 2
EMISSIONS REDUCED(G/S) • 75.
INITIAL COST (1000'S*) 149.
ANNUAL COST (1000'S*) -514.
FUEL COST (10E+9BTU) -207.
.Source ..Category-1
NUMBER OF USES
EMISSIONS REDUCED(G/S)
INITIAL COST (1000'SS)
ANNUAL COST (1000'S*)
FUEL COST (10E+9BTU)
. Source.. _Ca tegory_4
NUMBER OF USES
EMISSIONS REDUCED(GXS)
INITIAL COST (1000'S*)
ANNUAL COST (1000'S*)
FUEL COST (10E+9BTU)
Source Category 6
NUMBER OF USES
EMISSIONS REDUCED 1
42
122.
696.
-1038.
-758.
- 1
168
130.
2397.
-6873.
•2849.
1
23
77.
0.
1013.
362.
Source "Category 7^
NUMBER OF USES
EMISSIONS REDUCED(G/S)
INITIAL COST (1000'S*)
ANNUAL COST (1000'SS)
FUEL COST (10E+9BTU)
1
123
307.
1714.
-3002.
-1308.
.Source .Category 8
NUMBER OF USES
EMISSIONS REDUCED(G/S)
INITIAL COST (1000'S*)
ANNUAL COST (1000'SS)
FUEL COST (10E+9BTU)
_Source Category. 9.
NUMBER OF USES
EMISSIONS REDUCED(G/S>
INITIAL COST (1000'S*)
ANNUAL COST (1000'S*)
FUEL COST (10E+9BTU)
6
57.
1152.
304.
0.
1
2.
0.
0.
0.
•^
0
0.
0.
0.
0.
2
0
0.
0.
0.
0.
2
0
0.
0.
0.
0.
2
0
0.
0.
0.
0.
2
309
1322.
8559.
3509.
202.
2
1
. 49.
816.
301.
61.
2
0
0.
0.
0.
0.
*»
0
0.
0.
0.
0.
TECHNOLOGY
3
14
320.
1546.
346.
0.
TECHNOLOGY
3
0
0.
0.
0.
0.
TECHNOLOGY
3
7
23.
148.
31.
0.
TECHNOLOGY
3
0
0.
0.
0.
0.
TECHNOLOGY
3
0
0.
0.
0.
0.
TECHNOLOGY
3
9
27.
, 326.
53.
0.
TECHNOLOGY
3
0
0.
0.
0.
0,
TECHNOLOGY
3
0
0.
0.
0.
0.
4
1
45.
2898.
748.
66.
4
0
0.
0.
0.
0.
4
3
11.
445.
172.
23.
4
21
1444.
7650.
3245.
•379.
4 '
0
0.
0.
0.
0.
4
52
190.
9055.
2709.
242.
4
0
0.
0.
0.
0.
4
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
TOTAL
27
889.
6270.
-681.
-1263.
TOTAL
o
75.
149.
-514.
-207.
TOTAL
52
156.
1289.
-835.
-735.
TOTAL
189
1574.
10047.
-3628.
-2470.
TOTAL
332
1399.
8559.
4524.
564.
TOTAL
185 .
573.
11911.
62.
-1004,
TOTAL
6
57.
1152.
304.
0.
TOTAL
1
•? ^
0.
0.
0.
a/
See Table 24 for legend
-49-
SOURCE: EEA, Inc.
-------
TABLE -23
_OQSI_.RY_COMmiS!ro& TYPE- 23R...A1T£IHISG_A 250._U qZmJ. STANDARD'
Source Category 1
NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
"source" 'Category ~Z ~
NUMBER OF USES
EMISSIONS REBUCEJHG/S)
INITIAL COST <1000'S»)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category 3
NUMBER OF USES
EMISSIONS REDUCED < G/S >
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category 4
NUMBER OF USES
EMISSIONS REDUCED < G/S >
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category 5
NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
... . Source _Cateao.ry_6_
"NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category /
NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category a
NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
Source Category 9
NUMBER OF USES
EMISSIONS REDUCED (G/S)
INITIAL COST UOOO'S*)
ANNUAL COST UOOO'S*)
FUEL COST UOE+9BTU)
1
139
3213.
14943.
-13342.
-10111.
1
273
3438.
7084.
-21866.
-8854.
— 1
159
636.
4478.
-6390.
-4685.
1
467
573.
8743.
-24569.
-10195.
1
132
1622.
79311.
24472.
3863.
1
40
342.
0. -
5051.
1804.
1
490
6921.
45468.
-79221 .
-34530 .
~ 1
42
580.
15072.
3966.
0.
1
8
20.
0.
0.
0.
2
12
369.
2586.
1771.
730.
2
26
705.
1591.
3531.
1233.
2
7
64.
349.
315.
150.
^
2
9.
196.
372.
122.
2
0
0.
0.
0.
0.
2
566
4219.
29445.
12254.
712.
^
13
76.
1263.
434.
S3.
2
0
0.
0.
0.
0.
2
0
0.
0.
0.
0.
TECHNOLOGY
3*
4
104 65
5549 . 5595 .
21611. 281676.
5213. 92835.
0. 11023.
TECHNOLOGY
3*
4
163 20
3670. 641.
64147. 8212.
23885. 5277.
4990. 279.
TECHNOLOGY
3 4
61 58 •
1003. 1213.
5578. 65355.
1165. 23175.
0. 2935.
TECHNOLOGY
3 A
**
27 218
133. 2607.
1523. 139190.
300 . 55444 .
0. 6220.
TECHNOLOGY
3 4
0 0
0. 0.
0. 0.
0. 0.
0. 0.
1
TECHNOLOGY
3 4
0 0
0. 0.
0. 0. —
0. 0.
0. 0.
TECHNOLOGY
3 4
78 366
1030. 1766.
16152. 110010.
2626. 34869.
0. 3321.
TECHNOLOGY
3 4
0 0
0. 0.
0. 0.
0. 0.
0. 0.
TECHNOLOGY
3 4
0 0
0. 0.
0. 0.
0. 0.
0. 0.
e-
if
0
0.
0.
0.
0.
75
7006.
525564.
198040.
21366.
5
0
0.
0.
0.
0.
0
0.
0.
0.
0.
0
0.
0.
' 0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
0.
0.
0.
5
0
0.
o.
0.
0.
TOT — 1
1 U 1 itU
320
14926.
320815.
86476.
1642.
THTAI
( U 1 ML.
359
15460.
606597.
208847.
19014.
TOTAL
285
2916.
75759.
18264.
-1600.
TOTAL
i w i nw
714
3322.
149652.
31547.
-3853.
TrtTAI
TOTnL
132
1622.
79311.
24472.
3863.
TOTAL
606
4361.
29445.
17305.
2516.
TflTAI
TOTAL
947
. 9792 .
172893.
-41293.
-31125.
TOTAL
42
580.
15072.
3966.
0.
TOTAL
3
20.
0.
0.
0.
a/
See Table 24 for legend
SOURCE; EEA, Inc.
-------
TABLE 24
LEGEND FOR TABLES 22 AND 23
Source
^Category Description
Technology
Utility Boiler
(coal)
Utility Boiler
(oil and gas)
Industrial Boilers
(coal)
Industrial Boilers
(oil and gas)
Gas Turbines
1C Engines
Industrial Pro-
cess Combustion
Nitric Acid
1
LEA
LEA
LEA
LEA
Water
Inject
Engine
Modifications
LEA
Chilled
I
LEA+OSC
LEA+OSC
LEA+OSC
LEA+OSC
N/A
sea
LEA+FGR
N/A
I
Low NO
Burner
LEA+OSC
+FGR
Low NO
Burner31
LEA+OSC
+FGR
N/A
N/A
Low NO
Burner
N/A
£
SCR
LEA+OSC
+NH3
Injection
SCR
SCR
N/A
N/A
SCR
N/A
5_
-
SCR
S/A
N/A
N/A
N/*
N/A
B/A
Absorption
Municipal
Incinerators
-no control possible—-—
NOTE; LEA = Low Excess Air
OSC - Off Stoichionetric Combustion
FGR • Flue Gas Recirculation
SCR - Dry Selective Catalytic Reduction
N/A - Not Available
SOURCE; EEA, Inc.
-51-
-------
As noted in Section B.l.g., growth in point source
emissions was not considered since the methodology used for
the national assessment could not account for interaction
among point sources, and since major new sources of NO will
X
be adequately regulated by new source performance standards.
However, the impact of mandated mobile source controls (perhaps
the most obvious factor impacting future NO emissions) was
considered. Control costs were calculated for 1982 assuming
an approximately 20 percent reduction in background N02
concentrations due to a 1.0 percent increase in travel, a 30
percent reduction in the composite mobile source emission
factor, and no growth in stationary area sources. (This low
growth scenario leads to an even greater reduction in control
requirements than the high growth scenario shown in Table
12.) A comparison of the control costs with and without the
change in area source emissions is shown in Table 25.
"
0? __-• The change in both capital and annual costs are substan-
f> 3
_^ tial for a standard of 250 yg/m , but small for a standard of
>/•' 500 yg/m . However, these savings may be counteracted to an
undetermined extent by the location of new point sources at
sites where plume interaction is significant. In this case/
the assumption of plant isolation is not satisfied and control
costs would consequently rise.
5. Area Source Control Options and Costs
a. Stationary Sources
Current available techniques for the reduction of emissions
from space heating units are: (1) tuning — the best adjustment
in terms of the smoke-C02 relationship that can be achieved
by normal clean up, nozzle replacement, and simple scaling
and adjustment with the benefit of field instruments; (2)
burner replacement — installation of a new low emission burner;
and (3) unit replacement — installation of new advanced low
NO unit.
X -52-
-------
TABLE 25
IMPACT OF CHANGES IN AREA SOURCE EMISSIONS ON POINT
SOURCE CONTROL COSTS
Point Source Control Costs ($10 )
1975 Point and
Stationary Area Source
One Hour 1975 Point and Area Emissions, 1982 Mobile
Standard Source Emission Base Source Emissions
(yi'g/m ) Capital Annual Capital" Annual
500 46 - 1 34 ~1
250 1,496 363 809 124
' Low growth mobile source scenario: 1.0 percent growth in travel
and zero percent growth in stationary area sources.
SOURCE; EEA, Inc.
-53-
-------
Burner maintenance or replacement typically has a bene-
ficial impact on all pollutants except NO. Therefore, new
fuxaacss with advanced design or low NO emissions hold the
most promise for the control of NO from residential/commercial
space heating. These advanced designs are based on one, or a
combination of, combustion modification techniques described
briefly under the point source section. Low NO systems for
installation in new homes and stores are available at a cost
of ten percent or more above conventional systems. Replacement
of existing furnaces is obviously much more expensive (about
$700 for a residential furnace. } The NO emission reduction
potential of these new systems is up to 80 percent, and the
increase in operating efficiency is about ten percent.
Small gas- and oil-fired firetube boilers are used to
heat some commercial/institutional and many relatively small
industrial buildings. Existing units can be retrofitted (LEA
and FGR) at a capital cost of about $60 per million Btus/hr
capacity (annualized cost of about $.01 per million Btus),
while new boilers with improved burners would cost about
$40 per million Btu/hr ($.007 per million Btu/year) more
than conventional boilers.* Emission reductions would be
about 40 percent. However, many existing facilities would
require boiler replacement or supervision by full-time
18/
operators. A new boiler would cost up to $200,000 /.
b. Mobile Sources
The. Clean Air Act Amendments of 1977 mandate an emissions
standard of 1.0 g of NO per VMT for light duty vehicles
(LDV's) by 1981, which we have assumed extends through 1990 in
the baseline projections. The next step in a schedule of
increasingly stringent NO standards is 0.4 g/VMT. Based on
12/
information in the "Three-Agency Report," ' this could be
achieved for light weight cars by installing a three-way
'Assuming a 16 percent capital recovery rate,
-54-
-------
catalyst, together with an oxygen sensor in the exhaust stream,
a mechanical fuel injection system, and an upgraded electronic
control unit. These would replace the improved fuel metering,
air injection, start catalyst, and oxidation catalyst facilities.
For heavy autos (greater than 3,000 pounds), the incremental
control package includes electronic spark control, mechanical
fuel injectors, a switched air aspirator, a switched-start
catalyst, and an upgraded electronic control unit. (A three-
way catalyst is required, but is also needed to meet the 1.0
g/mile standard.) These replace a less exacting package of
fuel, ignition, and exhaust controls necessitated by the less
stringent standard. Though these specifications apply, strictly
speaking, only to autos, we will assume they apply to all
vehicles less than 6,000 pounds.
Additional capital costs are estimated to be approximately
$80 in 1985 (in 1977 dollars) for the control configuration
which is fuel-optimal. ' (The less expensive "cost-optimum"
configuration would incur substantially more in lifetime fuel
costs than the initial savings.) Lifetime maintenance expenses
are estimated at $30 ' or as a first approximation at a rate of
$3 per year. Though these are rough approximations of costs
for unproven technologies, they serve as useful initial esti-
matesT '""
Inspection and maintenance programs in individual AQCR's
could be instituted or expanded to cover NO emission controls.
X
Since I&M programs for NO currently do not exist, it is
„ ^ Ji
KJLmpossible to accurately gauge their costs and effectiveness.
Cost estimates for hydrocarbon and carbon monoxide I&M programs
which employ a dynamometer (a necessary ingredient for NO
X
emission tests) suggest that the inspection costs are approximately
$5 per test. ' Repair costs may also be incurred by vehicle
owners. However, in the absence of information on the size of
-55-
-------
'
"
these costs or on the possible fuel savings which may be
generated as a side benefit, repair costs are assumed to be
perfectly offset by fuel savings.
i
>_ Initial , first order estimates of the effectiveness of an
' 147
I&M program for NO have been made by EPA. ' A very optimistic
^
assessment is that all failures and maladjustments could be
•?
\> = :," detected and corrected for all autos manufactured after 1981.
^T EPA's mobile source emission model was run with the correspon-
• -"\* \
^ ding adjustments to the deterioration factors, and the results
\
^ . inputted to the area source model used here. A 28 percent
reduction in mobile source (highway vehicle) emissions is
produced in 1990.
6. Area Source Costing Procedure and Results
Based on the relative share of total emissions and the
unit costs of control, mobile sources appear to be much more
attractive candidates to focus on in strategies for achieving
alternative short-term NO- standards than do other area sources .
Stationary area sources emit a small fraction of total area
.. source NO (see Table 5) and are expensive to retrofit.
Jv
Replacing all existing residential, commercial, institutional,
and small industrial boilers and furnaces with low NO units
J^
would seem to be the only way to extract a sizable reduction
from these sources. A simple, first order assessment of
the costs and effectiveness of replacing all residential,
commercial/institutional and small industrial boilers in
each of the 150 AQCR's in this study indicated that the
«-,_ _. capital cost may be as high as $50 billion while only
-'- > three additional AQCR's would be able to achieve the 250
S. .-
X,
ug/m -^standards.
This analysis assumed that a replacement residential
furnace or hot water boiler would cost $700, replacement
units for commercial/institutional firetube boilers
would cost $120,000 for oil- or gas-firing and $200,000
for coal (spreader stoker), and replacement units for
industrial boilers would cost $150,000 (oil- or gas-
fired fire tube) and $300,000 (stoker watertube). Details
of this analysis were provided in a memorandum to EPA. '
-------
Consequently, the focus here is on mobile sources. Projec-
tions of the effectiveness of mobile.source controls are
generated by changing the composite mobile source emission
factor input to the rollback model, as noted before. Control
cost estimates are made separately.
The total additional cost of introducing a 0.4 g/mi.
emission standard in 1985 for those cars purchased between
1985 and 1990 can be estimated from the unit cost figures.
Assuming for purposes of this report that the California
and Federal regulations are identical (and thus, a 0.4
g/mi. standard would impose additional costs on Californians
as well), the total number of LDV's purchased between 1985 and
1990 can be projected knowing (a) the total VMT for each year
during this period of time; (b) the fraction of this total
driven by newly purchased LDV's during this period; and (c)
the average miles driven per year by new LDV's.
Estimates of annual nationwide VMT in 1985 to 1990 come
from the assumed annual growth rates (1.0 and 3.0 percent)
applied to the 1975 base year total: 1.17x10 miles for
light duty vehicles. ' Using EPA's estimates of .106 for the
fraction of total annual VMT accounted for by new LDV's, ' and
EPA's .estimate of 15,900 miles for the average VMT per new
LDV, total new LDV's were estimated for each year between 1985
and 1990: ---.•• . • ' -.,-./ ..'J---'
jl) VMT19g5 >199o = ^^1975 x Ccompounded annual growth rate)
LDV's Purchased1985_1990 = VMT19B5_ >199Q x
(New LDV VMT as a fraction of total VMT.)
(Average VMT per new LDV)
-57-
-------
This computation produces an estimated total capital
outlay for mobile source NO controls of from four to over
H
five billion dollars (5.3 - 6.7 million cars § $80), dependent
on the assumed mobile source growth rate. Annual costs in
1990 may be from $0.8 to over 1.0 billion, and include the
annualized capital charged (.16 capital recovery factor) and
$3 per year maintenance charge for each vehicle. Again, these
numbers should be viewed as rough, first approximations only.
Most significantly, the uncertainty attached to the unit cost
estimates is high.
The estimate of aggregate control costs for inspection
and maintenance programs is straightforward. The number of
autos currently registered (projected to 1990) can be used to
set an upper bound to these costs. The 1990 projection is in
the neighborhood of 150 million cars nationwide.* At about $5
per auto, this is $750 million. Thus, the annual costs for
vehicle owners in those AQCR's not attaining the standard will
likely be less than $750 million-,. The actual cost is dependent on
the fraction of all cars registered in these AQCRs. Capital
expenditures are related to the number of testing facilities
needed and thus to the number of AQCRs implementing I&M programs.
Projection of the effectiveness of mobile source control
programs and the total costs of control appear in Table 26.
It is readily apparent that going to a .4 g/mi. emission
standard for new light duty vehicles is extremely cost ineffective
There were 106 million registered autos in 1975. '
-58-
-------
TABLE 26
THE IMPACT OF ADDITIONAL MOBILE SOURCE NO CONTROLS ON THE
X
NUMBER OF NONATTAINMENT AQCR'S FOR ALTERNATIVE ONE-HOUR
AND THE COST FOR APPLYIN
(High Growth Assumption)
N02 STANDARDS AND THE COST FOR APPLYING THE CONTROLS
250 yg/m Standard
Strategy
Baseline
New Exhaust
Standard (.4g/mi.)
New Exhaust
Standard plus I&M
I's Not
Attaining in 1990
73
68
49
500 yg/m Standard
Control Cost
(billions of $)
Capital
4.2-5.4
4.2-5.4
a/
Annual
0.' 8-1.1
Strategy
Baseline
New Exhaust
Standard (.4g/mi.)
New Exhaust
Standard plus I&M
I&M Alone
AQCR's Not
Attaining in 1990
0
0
Control Cost
(billions of $)
Capital
4.2-5.4
4.2-5.4
— a/
a/
a/Does not include capital costs for I&M.
b/Based on estimates of LDV's in those AQCR's which have to
implement I&M Programs.
SOURCE; EEA, Inc.
Annual
0.3-1.1
<.5
b/
-59-
-------
Whereas the present mobile source control schedule will
effect major reductions in fleet-averaged emissions (emission
factors for early 1970 model years were greater than 5.0
g/VMT) , the change from a 1.0 to a 0.4 g/VMT standard brings
but a small additional improvement in AQCR attainment, but
levies a heavy cost burden on all vehicle owners. An I&M
program for NO is seen to be much more cost effective, though
a
the cost estimates are only rough approximations.
Even with both control programs in effect, perhaps as
many as 50 AQCR's will be unable to achieve a 250 yg/m
standard in 1990. Again, this assumes a high growth rate for
area sources, that area sources are primarily responsible for
the violation, and that hourly peaks are at least six times
the recorded annual average NO- level in all AQCR's. In these
AQCR's, point source controls beyond those required as per the
point source analysis would likely be necessary. For a 500
ug/m standard, an I&M program in fewer than ten AQCR's would
be needed.
E. Comparison of the Nationwide Cost Analysis With the Chicago
Case Study
Multiple Point Source Interaction
v
Point sources were nedelled individually as isolated
plants in the nationwide analysis. Further, the estimated
maximum concentrations due to each source in a plant were
considered additive irrespective of the location of maximum
impact. These locations could vary due to differences
among sources in the same plant in terms of operating charac-
teristics, stack location, and stack characteristics. The
first simplification results in an underestimation of the
short-term NO. problem where multiple plants are located close
-60-
-------
enough for plume interaction to be significant. The second
simplification should result in an overestimation in all
cases. The two opposite errors tend to compensate each other
to some extent where multiple plants are involved. But the
degree of over- or underestimation is a multi-variate function
of the relative location of different plants and sources
within a plant. A uniform adjustment across all plants to
compensate for these simplifications is not justified.
As noted previously, an interactive point and area source
model was used for the Chicago case study. A comparison of
the modelling results from the two studies (Chicago case study
versus Chicago portion of the National study) provides a basis
for ascertaining the degree of error introduced by the above
simplifications. The two studies differed in many respects
as described in Table 27. The major difference was the
treatment of ambient contributions from sources within each
plant and the interactions among plants.
Table 28 shows a comparison of the point source control
costs to achieve the 250 yg/m standard for the 1982 area
source low growth case.
The results are very similar, even though there are
significant differences in the analytical approaches and the
data bases used. The over-and under estimations introduced in
the nationwide analysis by (a) ignoring point source interac-
tions., and "(b) summing the maximum concentrations of all sources
within a plant appear to have balanced out. It may, there-
fore, be fair to say that the point source costs estimated on
a nationwide basis are not seriously biased by the simplifi-
cation employed in the analysis.
F. Economic Impact
1. General Comments
-61-
-------
TABLE 27
MAJOR DIFFERENCES BETWEEN THE NATIONWIDE ANALYSIS
AND THE CHICAGO CASE STUDY
Treatment of Point Sources
K>
I
Treatment of Area Sources
Data Sources
4. Dispersion Model
Nationwide Analysis
Each plant was considered
individually.
The maximum ambient conferir
bution from all sources
within the plant were
summed, irrespective of where
the points of maximum impact
were located.
Ambient contributions were
estimated from the regionwide
highest observed annual average
NO , and incorporated as a
background value.
NEDS Point Source File was used.
PTMAX, a single source model,
was used with no mixing
height limit.
Chicago Case Study
Interaction of sources
within and among plants
was considered by estima-
ting the ambient contribu-
tion of each at each recep-
tor in a specified network
Emissions from area source
grid cells and their impact
on ambient levels were
modelled explicitly
Combination of NEDS and Illinois
EPA files were used, with the
latter updated and allocated on
an hourly basis by Radian Corp.
RAM, a multiple area and point
source model, was used with a
mixing height limit.
SOURCE; EEA, Inc.
-------
TABLE 28
COMPARISON OF THE CHICAGO AQCR RESULTS OBTAINED IN THE
NATIONAL AND CHICAGO CASE STUDY ANALYSIS
(250 pg/m3 N02 STANDARD)
National Analysis
a/
Chicago Case
Study Analysis
b/
Capital
Cost
Annual
Cost
(106 $) (106 $)
123
34
Capital Annual
Cost Cost
(10° $)
131
(10° $)
21
b/
Case 4 with a 20 percent reduction in area source emissions.
Intermediate meteorological conditions with a 20 percent
reduction in area source emissions.
SOURCE: EEA, INC.
-63-
-------
A detailed assessment of economic impacts is beyond the
scope of this analysis. The nationwide scope of the study and
the diverse nature of affected sources precludes an investiga-
tion of impacts on product prices and financial conditions
within specific industries. Instead, a qualitative discussion
of likely impacts is drawn from the cost analysis.
2. Point Sources
It would appear from the preceding discussion that the
expense of additional NO emission control needed to meet a
A
short-term NO- standard will be borne by a variety of sources.
Table 29 shows a distribution of control costs by industry for
the 250 ug/m standard. At this level, plants in 14 different
categories have to institute NO controls. However, over one-
3C
third of all plants are utilities. More importantly, required
controls at power plants account for-almost 75 percent of
total control costs. This results from the large size of
utility boilers and the fact that several must be controlled
to advanced levels (i.e., retrofit of low NO burners or the
t *•>
use of dry SCR). This unequal distribution of costs combined
with the low expenditure total for all point sources indicates
that utilities are the only category of point sources likely
to experience significant economic impacts.
A closer lool: at the total cost burden accruing to utilities
indicates that the estimated cost levels are indeed modest.
The slightly more than $1 billion capital cost will be spread
over approximately 150 plants, making the per plant cost less
than $10 million on the average. To put this cost in perspec-
tive, the estimated capital expenditure for NO controls on
-64-
-------
TABLE 2-9
COST OF N0x CONTROL BY INDUSTRY FOR A 250
yg/m3 N02 STANDARD
Capital Annual
No. of Cost
Plants (106 $)
Utility
Boilers
Internal Combustion - Reciprocating
Industrial - In Process Fuel Use
Gas & Oil Pipe Lines (I.e. Engines)
Refineries
Steel
Metal Melting
Asphalt
Lime Kiln
Glass
Cement
Food
Automotive
Wastewater Treatment
Miscellaneous
Non-Combustion
Chemical (nitric acid, etc.)
Total
136 1065
26 14
18 12
37 91
23 142
15 13
10
4
4
3
4
4
3
67 114
24 45_
408 1,496
Cost
(106 $)
334
3
6
-13
16
1
• -
-
-
-
-
-
-
10
6_
363
SOURCE: EEA, Inc.
-65-
-------
existing utility sources is less than five percent of the
estimated capital expenditures between 1976 and 1990 to meet
the NSPS for SO- now under consideration, and about 0.1 percent
of the total estimated capital expenditures by utilities for
the same period.
! We can conclude, with some confidence, that the economic
I impacts are unlikely to be large for point sources even for
the most stringent standard assessed—250 yg/m .
1
3. Area Sources
The cost analysis for area source controls points to a
much more significant level of expenditure to meet a 250 yg/m
standard ($4-5 billion capital—1985 to 1990, and $1 and $2
billion annual for a 0.4 g/mi. exhaust level and I&M program).
In addition, the impacts are likely to be experienced only
within one industry (auto and truck manufacturing! and directly
by consumers.
It seems likely that the cost of additional control
equipment needed to meet a 0.4 g/mi. exhaust standard (about
$80) would be passed along in total to auto and truck purchasers.
(Car prices would rise less than five percent.) This cost
r~_> V, plus the estimated $30 lifetime maintenance cost and $5 annual
.£ ^ ' inspection fee may discourage some potential buyers, thus
x-N- ^
\ V depressing sales industry-wide. More likely, the cost of
-! producing the necessary control equipment or engine modifications
may vary among manufacturers, especially between domestic and
foreign companies. To the extent that these lifetime cost
differentials are substantial, certain companies may be disadvan-
taged. Beyond this cursory assessment, little more can be
said at this time.
-66-
-------
G. Summary and Conclusions
• Either point or area sources alone can cause
violations of a 250 yg/m short-term NO, standard.
3
Short-term concentrations greater than 500 yg/m
are normally a result of their combined impacts. Of
the four standards tested, only a 250 yg/m one-
hour level would be difficult to attain. Perhaps
as many as 50 AQCR's would be in nonattainment in
1990 after area and point source controls were
in place.
• Emissions from point and area sources together
(under conditions that result in peak N02 concen-
trations overall) may lead to violations of a
250 yg/m standard in about 120 AQCR's. Under these
conditions, control of point sources alone can
result in attainment of the standard at a capital
and annualized cost of about $1.6 billion and
$340 million, respectively.
• Area sources alone under meteorological condi-
tions that maximize their impacts may lead to
current violations of the 250 yg/m standard in
about 95 AQCR's. Mobile source controls beyond
the mandated exhaust standards can bring 10 to 20
AQCR's into attainment of a 250 yg/m standard by
1990, beyond the 20 to 30 which may reach attain-
ment through the turnover of the vehicle stock.
Inspection and maintenance programs (less than
$750 million annual cost) appear to be much more
cost-effective than a .4 g/mi. exhaust standard
(about $4-5 billion capital and about $1 billion
annual).
-------
Point sources with multiple short
stacks seem to behave similarly to area
sources in terms of the meteorological
conditions which lead to maximum impact.
Their combined effects seem to be the
cause of high short-term N02 concentra-
tions in urban areas.
Point sources with high effective dis-
charge heights do not seem to present a sub-
stantial problem taken alone. But in the
presence of other point sources and/or area
sources, their contribution is significant
enough to require some degree of NO con-
3
trol. However, for 250 yg/m N02 stan-
dard, the cost of controlling these poinf
sources constitutes a large portion of the
total point source control costs due pri-
marily to the large size of their combus-
tors (boilers).
For short-term NO- levels of 500 ug/m and
above, the magnitude of the problem is
diminished significantly. Controls on
point sources alone should bring attain-
ment of the standard at all times in most
AQCR's. The capital costs of point source.
control to attain a 500 yg/m level are
about $46 million, while annual costs are
close to zero due to fuel savings. Between
five and ten AQCR's may still be in viola-
tion of this standard in 1990 due to area
source emissions. These could be brought
into attainment if an aggresive I&M program
were instituted in each AQCR at an annual
cost of a few hundred million dollars.
-68-
-------
REFERENCES
1. Memorandum from Joseph A. Tikvart (US EPA, Office of Air
Quality Planning and Standards) to Edward J. Lillis (US
EPA, Office of Air Quality Planning and Air Standards),
February 16, 1978.
2. John Trijonis, Empirical Relationships Between Atmospheric
Nitrogen Dioxide and its Precursors, EPA-600/3-78-018, EPA,
Office of Research and Development, Research Triangle Park,
North Carolina, February 1978.
3. Acurex Control Techniques for Nitrogen Oxide Emissions From
Stationary Sources—Revised Draft Second Edition, Aerotherm
Report, TR-77-87, Aerotherm Division, December 1977.
4. California Air Resources Board, Control of Oxides of Nitrogen
From Stationary Sources in the South Coast Air Basin, ARE
2-1471, September 1974.
5. US EPA, Compilation of Air Pollutant Emission Factors, AP-42,
3rd Edition, 1977.
6. Radian Corporation, "Impact of Point Source Control Strategies
on NO- Levels," Discussion Draft prepared for EPA, February
1978.
7. Thuillier, R.W., W. Viezee, "Air Quality Analysis in Support
of a Short-Term Nitrogen Dioxide Standard," Discussion Draft
prepared for EPA, SRI International, December 1977.
8. Bureau of Economic Analysis, U.S. Department of Commerce,
"Tracking the BEA State Economic Projections," April 1976.
9. Personal communication with Paul Stolpman, US EPA, Office
of Policy Analysis.
10. The estimates of future emission factors were computed
with EEA's mobile source emission model (Mobile 1).
11. Personal communications with Mike Evans of ACUREX (Aerotherm
Division).
-69-
-------
REFERENCES
12. U.S. Department of Transportation, U.S. Environmental
Protection Agency, U.S. Federal Energy Administration
(now the Department of Energy), An Analysis of Alterna-
tive Motor Vehicle Emissions Standards, May 10, 1977, as
revised on April 13, 1977, Tables A-7 and A-8.
13. B.F. Kincannon and A.H. Castoline, Information Document
Automobile Emissions Inspection and Maintenance Programs,
EPA, Washington, D.C., February 1978.
14. Personal communications from Paul Stolpman, US EPA,
Office of Policy Analysis.
15. Bhatt, K., M. Beasely, K. Neels, Analysis of Road Expendi
tures and Payments by Vehicle Class, 1956-1975, The Urban
Institute, Washington, D.C., March i§77. The figure for
total VMT by LDV's in 1975 (1.17x10 miles) was approxi-
mated from reported VMT for autos and trucks up to 12,000
pounds registered weight, the latter adjusted by the
percent of registered weight class. (This corresponds
approximately to the 0-6,000 pound chassis weight'class.)
16. Motor Vehicle Manufacturers' Association, MVMA Motor
Vehicle Guide, Facts and Figures, 1977.
17. Personal communication from Richard Jenkins, EPA, Office of
Air Quality Planning and Standards, Data on S02 scrubber
costs come from Paul Lashotopf, Temple, Barker and Sloan.
18. Based on EEA's experience in costing boiler systems.
19. Memo from Dale Keyes (EEA) to Kenneth Lloyd (US EPA,
Office of Air Quality Planning & Standards),
-70-
-------
SHORT-TERM N02 STANDARDS
VOLUME III
AN INVESTIGATION OF SHORT-TERM
CONCENTRATIONS IN CHICAGO
Draft Report
DRAFT
DO NOT QUOTE OR CITE
Submitted to:
Office of Air Quality Planning and Standards
Environmental Protection Agency
Research Triangle Park, North Carolina 27711
Submitted by:
Bharat Kumar and Dale L. Keyes
Energy and Environmental Analysis, Inc.
1111 North 19th Street, 6th Floor
Arlington, Virginia 22209
December 27, 1978
-------
TABLE OF CONTENTS
SHORT-TERM N02 STANDARDS
VOLUME III
Page
A. Introduction ' 1
B. Air Quality Assessment 2
1. Selection of a Case Study AQCR 2
2. Ambient NO- Concentrations in Chicago .... 3
3. Modelling Approach 3
4. Modelling Results and Discussion 13
C. Assumptions and Limitations 18
D. Relationship of Estimated Area Source One Hour
Concentrations to Observed Annual NO- Levels ... 20
E. Control Options and Cost Analysis 23
G. Summary and Conclusions 26
REFERENCES 31
APPENDIX A • 32
REFERENCES TO APPENDIX A 39
-------
LIST OF TABLES
SHORT TERM N02 STANDARDS
VOLUME III
Table 1;
Table 2:
Table 3
Table 4;
Table 5:
Table 6:
Table 7;
Yearly Highest and Second-Highest 4
One-Hour NO- Levels (ug/m )
Meteorological Conditions Used in 11
The Analysis
Comparison of Estimated NO- Levels From 16
Point and Area Sources Under Different
Meteorological Conditions in Chicago
Comparison of Estimated Average One-Hour 22
NO- Concentration Due to Area Sources Alone
(For all Modelled REceptors) with the
Highest Observed Annual Average in 1975
in the Chicago AQCR
Point Source Control Costs to Meet a . 25
One-Hour NO- Standard of 250 ug/m in
Chicago AQCR
Comparison of the Chicago AQCR Results 27
Obtained in the National and Chicago Case
Study Analysis
Major Differences Between the Nationwide 28
Analysis and the Chicago Case Study
-------
LIST OF FIGURES
SHORT-TERM N02 STANDARDS
VOLUME III
Figure 1: Seasonal-Diurnal Variation in NO • 5
and NO- for Plymouth Court Monitoring
Station
Figure 2: Seasonal-Diurnal Variation in NO 6
and NO- for West Polk Monitoring Station
Figure 3: Seasonal/Diurnal Variation in NO and 7
N02 at Joliet Station
Figure 4: Estimated Highest One Hour Average N02 17
Concentrations in Chicago - 1975
Figure A-l: Diagrammatic Representation of Programming 37
Problem (Two-Receptor Case)
-------
VOLUME III
AN INVESTIGATION OF
SHORT-TERM N02 CONCENTRATIONS IN CHICAGO
A. Introduction
This is the third volume of a three-volume report which
attempts to identify the causes of high short-term concentra-
tions of nitrogen dioxide (N02) and the additional cost of
controlling sources of nitrogen oxides (NO ) emissions to
X
levels consistent with attainment of the ambient standards
under consideration. (The costs in addition to those required
to meet the Federal Motor Vehicle Emission Standards and the
NSPS for stationary sources.) Volume I focuses on the mechan-
isms by which high ambient concentrations of NO- are believed
to occur. Volume II provides a preliminary assessment of the
sources which, through the mechanisms identified in Volume I,
might cause or contribute to high short-term (i.e., one-hour
averaging period) concentrations of N0_. Control strategies
are developed for these and used to estimate nationwide control
costs. This volume describes a detailed case study of short-term
NO- concentrations in Chicago, the results of which are used
in Volume II as input to and for comparison with the point source
analysis.
The levels of N02 observed on an hourly basis in any
large region are the product of emissions from a myriad of
sources. In order to fully capture the interactive nature
of these emissions and the relative importance of each
-1-
-------
-2-
source, a multiple point and area source dispersion model is
required. A modelling exercise of this type for every AQCR
in the country is obviously prohibitive from a cost standpoint.
Instead, a separate detailed study of a single AQCR was
undertaken to serve as a point of comparison for the simplified
nationwide study. The results of this investigation shed
light on the contributions of point and area sources to the
short-term NO, problem in an urban area under different
meteorological conditions. In addition, the relative contri-
bution of area sources to peak hourly concentrations observed
in Chicago provides a rationale for incorporating an area
source background in the nationwide point source analysis.
B. Air Quality Assessment
1. Selection of a Case Study AQCR
Chicago is a logical choice for this analysis:
• Chicago is one of the five AQCR's in
the nation recording violations of the
annual average NO- standard, suggesting
a high potential for short-term viola-
tions as well.
• The point and area source NO emissions
H
inventory for Chicago is relatively com-
plete as a result of several recent
studies conducted there. '
• Chicago, a classic urban-industrial
area, presents a good opportunity to
study interactive effects of both
point and area sources. The N0_ pro-
blem in Chicago can be assumed repre-
sentative of most other urban AQCR's in
the country.
-------
-3-
2. Ambient NCU Concentrations in Chicago
Ambient N02 data in the Chicago AQCR are inadequate, taken
alone, for characterizing and assessing the short-term NO-
problem. There are only four continuous NO-/NO monitors in
^ it
the Chicago region, far below what would be required for an
area of approximately 150 x 80 km. However, the four sites can
be considered representative of some of the most severely
impacted locations in the region. The peak one-hour N02
levels normally observed at these sites are among the highest
concentrations observed in other urban areas of the country.
Table 1 shows the highest and second highest one-hour N02
levels measured annually at the four continuous monitors in the
region during the past three years.
Figures 1, 2, and 3 show the diurnal variation in the N02
and NO levels for the summer and winter seasons at the Plymouth
X
Court (Camp), West Polk (Medical Center), and Joliet monitoring
4/
stations. These patterns reflect the influence of mobile
source NO emissions (morning and evening rush hours) typical
J^
of urban areas. The NO- levels show a less pronounced double
peak which is also typical, while the Camp station reflects an
early afternoon bulge characteristic of point source influences.
3. Modelling Approach
a. Model Description
A multiple point and area source model, known as RAM, was
used for assessing short-term NO concentrations. ' RAM is an
ji
EPA-approved Gaussian steady-state model capable of predicting
short-term (averaging times ranging from an hour to a day) am-
bient concentrations of relatively stable pollutants from
-------
TABLE 1
Monitoring
Site Location
Camp
Medical Center
Joliet
La Salle
YEARLY HIGHEST AN,D SECOND
1975 '
Second
Highest Highest
1-hr. N02 1-hr. N02
394 385
678 616
857a 812a
HIGHEST ONE-HOUR N02 LEVELS
1976
Second
Highest Highest
1-hr. N02 1-hr N02
490 , 470
394 354
262 250
1977
Highest
Second
Highest
1-hr. N02 1-hr. N02
1008
494
604
968
488
524
a
Questionable data.
SOURCE: Illinois EPA
-------
-5-
FIGURE 1
WINTER
I2M
SUMMER
NOV
13M
PLYMOUTH COURT (CAMP STATION) UTM- (450. 4830)
SOURCE:
Seasonal-Diurnal Variation in N0x and N02
Plymouth Court Monitoring Station
Reference 1.
for
-------
-6-
FIGURE 2
WINTER
13M
I2M
SUMMER
.21 •
.it •
.a*-
-
£ 300-.,..
ui
u
.!*•
aoo-
.10 1
too- •"•
.04 -
.03 •
0-
NO,
13M-
•*
13N
ISM
WEST POLK (MED CENTER)
UTM • (4.45.
Seasonal-Diurnal Variation in NOX and N02 for
West Polk Monitoring Station
SOURCE: Reference 1.
-------
-7-
FIGURE 3
SEASONAL/DIURNAL VARIATION IN NOX AND NOZ AT JOLIET STATION
CONCENTRATION (PPM)
0.3 1
0.2
0.1
HNTER (JANUARY 24,1977)
12M
6A
12N
i
6P
12M
CONCENTRATION (PPM)
U
0.2 -
0.1 -
SUMMER (JULY 8,1977)
12M
SOURCE: EEA. lac.
6A
12N
i
6P
12M
-------
-8-
multiple point and/or area sources. Hourly meteorological data
required are wind direction, wind speed, stability class, and
mixing height. Required data on point sources consist of
source coordinates, hourly emission rate, stack height, stack
gas volume flow, and temperature. Area sources are specified
in terms of south-west corner coordinates of the area source
grid, grid cell area, total cell emission rate, and the effec-
tive area source height.
As noted, RAM is designed for modelling nonreactive
pollutants. Nitrogen dioxide, on the other hand, is primarily
a secondary pollutant formed by oxidation of NO. The initial
NO concentration in the exhaust gases, the plume diffusion and
travel time, and the ambient concentration of photochemical
oxidants and reactive hydrocarbons are the most important
factors that affect the conversion of NO to N02« An empirical
representation of NO- formation from point source emissions of
NO , developed by EEA, has been used in conjunction with RAM to
Ji
translate the predicted NO into NO, concentrations. A dis-
2C £
cussion of this approach is presented in Volume I.
A different approach was used for area sources. A fixed
NO-/NO ratio for each period of the day, based on observed
+* Xt
data at the continuous monitoring sites, was used to relate
predicted NO and NO- levels. This is further discussed in the
X «b
Assumptions and Limitations Section.
b. Point and Area Source Emission Data
A partial list of point source emissions, together with
stack parameter data, was obtained from Radian Corporation and
corrected for errors. Additional sources of NO , along with
Jt
other pertinent data such as source operating rate and certain
classification codes, were obtained from EPA's NEDS point source
subfile and the Illinois EPA. Hourly NO emissions obtained from
X
-------
-9-
Radian were adjusted to reflect the diurnal and seasonal
variation in the operating loads. The temporal variations
in the operating loads of power plants and space heating
operations were found to be more significant than those in
the industrial operations. Emission factors for most utility
boilers and combustion turbines were based on actual stack
test data. For other point sources, the recent emission
factors from the Oxides of Nitrogen Control Techniques
Document, (Second Edition) , California Air Resources Board
ARB2-1471,3' and AP-42 (Second Edition) ' were used. The
point source data were screened for erroneous and missing
information. Default values for the various parameters were
substituted based on what constitutes normal operating practice
in a particular process category. Data on a total of 813 sta-
tionary processes belonging to about 286 plants were thus
compiled.
For the final analysis, point sources emitting below ten
pounds NO per hour were considered too small to be treated indi-
JL
vidually and were lumped with the area source inventory. This
was done mainly to reduce the point source input to RAM to a more
manageable size. The final input to RAM consisted of 457 point
sources (i.e., SCC's).
Hourly NO emission estimates for mobile and stationary
ji
area sources in the Chicago region were provided by Radian Cor-
poration. Vehicular data from the Chicago Area Transportation
Study (CATS) were used by Radian to convert the 1975 annual
average mobile source emissions (taken from NEDS) into hourly
emissions in the summer and winter seasons. The mid-morning
and afternoon hourly emission rates estimated in this manner
were apportioned to 5 x 5 km grid cells. Input data to the
-------
-10-
area source subroutine of RAM then consisted of 640 cells. A
finer spatial resultion than a 5 km spacing would have made
the computer time requirements prohibitive.
c. Meteorological Data and Selection of Worst Case
Conditions
Meteorological conditions play a major role in the short-
term build-up of pollutants from both point and area sources.
High ground level concentrations of NO (but not necessarily NO.)
X fc
from point sources are normally caused by fumigation (inversion
breakup) or plume downwash where the plume intersects the
ground quickly. Though these conditions can not be simulated
explicitly by RAM, the following meteorological conditions .
are good surrogates: -stability class B or C (unstable atmos-
phere) and moderate to high wind speeds.
On the other hand, the greatest impacts of ground level
sources, such as vehicles and other area sources, occur when the
atmosphere is quite stable (stability class of D or E), wind
speeds are low, and mixing heights are small. The meteorological
conditions that maximize the impact of either point sources or
ground level area sources are thus at two opposite extremes,
making it difficult to maximize their impact simultaneously.
Instead, several intermediate sets of conditions were used to
simulate worst case conditions for point and area sources
together.
The meteorological data for the Chicago region were
extrapolated from the mixing height and wind speed data collected
by the National Weather Service at their Green Bay, Wisconsin,
Peoria, Illinois, Flint, Michigan, and Dayton, Ohio stations.
Typical meteorological conditions, as well as those that
correspond to stagnant and unstable atmospheres in the Chicago
region, are listed in Table 2.
-------
TABLE 2
METEOROLOGICAL CONDITIONS USED IN THE ANALYSIS
Conditions
Season and Hour of the Day
Summer Mid-morning
Summer Afternoon
Winter Mid-morning
Typical
Wind Speed
Mixing Height
Stability Class
Wind Direction
Ambient Temperature
4.0 meters/sec.
650 meters
C
90°
70°F
6.5 meters/sec.
1600 meters
D
225°
80°F
6.0 meters/sec.
450 meters
D
315n
20°F
Worst Case - Point Source
Impact
• Wind Speed
• Mixing Height
• Stability Class
• Ambient Temperature
Worst Case - Area Source
Impact
• Wind Speed
• Mixing Height
t Stability Class
• Ambient Temperature
Predominant Wind
Directions
2.5 meters/sec.
300 meters
C
70°F
0.5 meters/sec.
300 meters
C
70°F
90
o
4.5 meters/sec.
800 meters
B
80°F
2.5 meters/sec.
800 meters
80°F
180
225*
2.5 'meters/sec.
30o meters
C
20°F
1.5 meters/sec.
200 meters
20°F
275
215
o
SOURCE: EEA, Inc.
-------
-12-
d. Selection of Receptor Locations
A total of 374 receptors were initially selected for
the entire AQCR and were located so that the maximum impact
of all significant point and area sources could be captured.
The first 70 receptors correspond to locations of the con-
tinuous and 24-hour N0_ monitoring sites in the Chicago
AQCR. The remaining receptors were selected by the model
downwind of significant point and area sources at points of
expected maximum concentrations. The receptor selection
process was as follows:
The most significant point and the 100 most significant
area sources (i.e., grid cells) were first identified, based
on their relative contribution to ambient levels. Two
receptors downwind of each major point source and one for
each major area source were selected. The first receptor
for each point source was positioned at the estimated -point
of maximum ambient concentration; the second receptor, in
the same direction but twice as far away as the first, was
designed to capture the interaction of overlapping plumes.
The single receptor for each area source reflected the
maximum impact from each area source.
The 100 receptors corresponding to major area sources
were eliminated after the preliminary modelling runs, indicated
low total NO- concentrations at these receptors under meteorolog-
ical conditions which maximize point source influences. For
the analysis of maximum area source influences, 27 of the
area source receptors were included. The model was run for
five predominant wind directions in the Chicago region to
capture the interaction of various sources for the purpose
of developing control strategies.
-------
-13-
4. Modelling Results and Discussion
Several preliminary runs of the model were made to
determine the combinations of hourly emissions and meteoro-
logical conditions that would result in the highest short-
term NO- concentrations.* Maximization of area source
impact resulted in high concentrations at a large number
of receptors. The point source maximization, contrary to
expectations, resulted in peak N02 concentrations lower than
those estimated in the former case.** The area source NO-
component under these conditions is significantly lower and
may have been underestimated due to limitations of the
model. An intermediate set of adverse meteorological condi-
tions was therefore selected to capture large contributions
from both point and area sources which, when combined, could
result in the highest short-term NO- levels. The meteoro-
logical conditions used for the final analysis are: wind
speed—1.5 meters/second, stability class C, and mixing
height—300 meters. The NO emissions for the analysis
a
correspond to the 1975 summer mid-morning levels.
The results obtained point to the presence of two distinct
types of point sources: 1) large plants with tall stacks
such as power plants and incinerators, and 2) plants with a
large number of smaller sources with short stacks such as the
steel mills and refineries. The diffusion characteristics of
emissions from the second category were found to be similar
to those of the area source, emission-s. During meteorological
conditions which cause high concentrations of NO- from both
area sources and point sources with short stacks, the contribution
* Preliminary runs wer-e made using a portion of the Chicago AQCR
which included Cook, Dupage, and portions of Will, Lake, arid
Porter Counties.
** See Table 2 for the meteorological conditions used to maximize
area and point source influences separately.
-------
-14-.
from power plants and other sources with high effective stack
heights was low. Under other extreme conditions, point
sources with tall stacks could have a greater individual
impact, but these conditions tend to minimize the impact
of other source categories resulting in overall lower concen-
trations. Table 3 compares the relative point and area source
contributions to ambient NO- levels under three different
meteorological conditions. High hourly N02 levels can be pro-
duced under conditions favoring either area or point source
influences. The highest levels are likely to occur when
meteorological conditions allow both types of sources to
exert significant effects.
Table 3 also shows the percentage of power plants with
significant contributions. At low wind, speeds, the predicted
contribution due to most of these sources is negligible. This
is, in part, due to the limitation of the model. At low wind
speeds, the point source plumes penetrate through the mixing
layer at depths assumed in this study, and the diffusion model
assumes their contribution as zero. Under certain circumstances,
however, the plume could be trapped below the inversion lid and,
during the morning inversion-breakup, could fumigate to the
ground and cause high NO concentrations. Whether this phenom-
J&
enon could also lead to very high NO- concentrations is a subject
for further research. Ozone concentrations in the morning are
generally low and the degree of plume mixing during fumigation
may_be limited. Both of these factors may lead to low NO,/NO
^ X
ratios.
-------
TABLE 3
COMPARISON OF ESTIMATED NO LEVELS FROM POINT AND AREA SOURCES UNDER DIFFERENT
METEOROLOGICAL CONDITIONS IN CHICAGO3/
Five Highest Worst Case - Point
Concentrations Total Point
1 509 428
2 589 409
3 348 209
4 348 225
5 342 219
Average of
all receptors
above 200
pg/ra 277 165
Number of Receptors
Above 200 |Jg/m3 47
Percentage of Power Plants
With Significant Contribu-
tions, i.e., Effective Stack
Height Less Than Mixing
Height 17
Chicago Case Study - Cook, Dupage
The receptors used in the analys
receptors may reflect higher area
C/ See Table 2.
' W-inH crloorl — 1 ^m/a o*--,Ki 1 i 4-, . „! —,
C/ r/
Source Worst Case - Area Sourcej^
Area Total
81 568
81 479
139 472
123 472
123 472
111 371
Point Area"'
549 19
279 200
272 200
272 200
272 200
142 199
68
0
, and portions of Will, Lake and Porter
is were selected to record maximum total
source contributions, but lower total c
Intermediate Case^/
Total Point Area
603 493 110
602 434 168
600 407 193
598 430 168
553 383 170
316 142 174
67
3
Counties .
concentration. Other
oncentrations .
i
Ul
I
-------
-16-
These findings for large point sources are at variance
with the Radian conclusions. ' It would appear that the
differences are due to (a) the use of a much higher NO emission
H
factor for cyclone boilers by Radian, (b) erroneous emissions
for some point sources in the emission inventory used by Radian
and Radian's use of constant NO-/NO values as compared with
M X
our time-dependent ratios. In' addition, EPA reports that the
Radian treatment of summer morning atmospheric dispersions was
somewhat unrealistic leading to high .NO values. '
As noted previously, ambient N02 levels in Chicago indi-
cate little variation between the morning and afternoon peaks
at the four continuous monitors. This is a departure from the
typical situation. Pronounced morning and afternoon NO- peaks
with low concentrations at noon due to increased vertical mixing
are normally observed in most urban areas where NO- is predomi-
nately an area (mobile) source problem. This may be due to the
high noon-time power plant load in Chicago, which is 50 to 80
percent higher than the mid-morning load in both the summer
and winter seasons. Further, most industrial batch opera-
s
tions are at their peaks during the noon period. Thus high
NO- concentrations at noon in Chicago can be attributed to
the multiple point sources.
As noted, the intermediate set of meteorological conditions
produced the highest hourly NO, concentrations. Figure 4 shows
the five highest (of the 274) N02 estimates and the relative
contributions of the two source types to them.
-------
FIGURE 4
ESTIMATED HIGHEST ONE HOUR AVERAGE NO2
CONCENTRATIONS IN CHICAGO - 1975
(Intermediate Case-Meterorlogical Conditions)
AMBIENT
N02 LEVELS
(ug/ro>)
700
600
500
400
300
200
100
AREA
75
274
202
RECEPTOR NUMBERS
254
228
SOURCE: EEA, Inc.
-------
-18-
C. Assumptions and Limitations
An interactive diffusion model, a detailed point and area
source emissions inventory, and a relatively sophisticated
approach for translating the estimated NO to NO- concentrations
Ji 4b
have been used in this analysis. Nevertheless, the prediction
models have several limitations, and simplifying assumptions had-
to be made. The assumptions and the limitations they place on
the results are described below.
• The meteorological conditions are assumed to
hold for a period of one hour and to be uni-
form over the whole region. The latter is
not likely to be true because of intra-regional
variations in topography. In addition, center
city meteorological conditions are considerably
altered by the built environment, but a micro-
scale analysis seemed unwarranted in view of the
objective of the study and resource limitations.
The NO- concentrations may have been underesti-
mated at downtown sites.
Mobile source emissions are uniformly dis-
tributed throughout each grid cell. This
results in a loss of spatial resolution which
may reduce the impact of these emissions on
air quality. Ambient levels of mobile source
pollutants (HC, CO, NO ) tend to peak next
a
to the roadways and normally diffuse to low
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-19-
values within relatively short distances,
inferring considerable spatial variation in
their concentrations. Therefore, NG>2 levels,
even though considerably smoothed due to
the slow conversion of NO to N02, may still
be significantly higher in the vicinity of
roadways. Some version of a highway model
for estimating the impact of mobile sources
would be needed to more accurately assess
this effect.
Ambient levels of NO due to point source
J\
emissions were translated into NO- concen-
trations by the use a time-dependent, plume-
specific approach incorporated into RAM.
Volume I of this study contains an explana-
tion of the approach. Area sources were
treated differently. A constant NO-/NO
£ Jk
ratio of 0.5 was derived from hourly N02
and NO data for the summer morning period
a
at the continuous monitoring stations in
Chicago. (The N02/NOX ratios ranged from 0.4
to 0.6.) These monitors are likely to be
influenced by mobile sources at these times.
The factor of 0.5 has been assumed to apply
to all area sources. NO emissions from
X
area sources within relatively short dis-
tances of their discharge are characterized
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-20-
by rapid atmospheric mixing. It is there-
fore reasonable to assume that the ratio of
NO- to NO concentrations from area sources
£» •**
would be about the same, especially where
the sources are fairly evenly distributed in
space. The narrow range of NO-/NO ratios
fc a
observed at the continuous monitoring sites
further supports -this deduction. However, a
conversion ratio of 0.5 must be considered
little more than a rough,. initial approxima-
tion at this time.
The model is incapable of predicting
ground level concentrations from point
sources under certain unusual meteorolog-
cal conditions such as morning inversion-
breakup (fumigation), though other conditions
can be used as surrogates. Secondly, the
model assumes no impact on air quality from
sources with effective plume heights above
the mixing layer. For these reasons, NO-
concentrations from large point sources may
have been somewhat underestimated.
D. Relationship of Estimated Area Source One Hour Concentra-
tions to Observed Annual NO., Levels
One of the objectives of this case study was to empiri-
cally assess the nature of the area source problem and, if
possible, develop a relationship between the estimated peak
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-21-
one-hour levels and the observed annual average N02 concen-
trations. By examining this relationship under meteorolog-
ical conditions which favor contributions to ambient levels
from point sources, area source additions to the modelled
point source levels could be derived for use in the nation-
wide study. The results of this investigation were incor-
porated in the nationwide study as reported in Volume II.
Referring back to Table 3, one can see that the average
area source contributions to ambient levels in each of the
•three cases is very close to the area source contribution
at the receptor with the highest total concentrations. That
is, the spatial variation in the area source component of peak
hourly N02 concentration is low. However, some loss of spatial
detail in the area source concentrations could have resulted
from limitations in the way RAM models area sources, as noted
earlier. Regardless, limited empirical evidence on hourly N02
levels observed supports the above deduction. The use of a
single value to account for the area source contribution at all
receptors in an AQCR is therefore reasonable.
To quantify the area source background level for the two
sets of meteorological conditions used in the national study,
the average area source contributions to the peak one-hour
levels determined conditions in the Chicago case study
were related to the highest observed annual average N02 con-
centration in the Chicago AQCR. Table 4 shows a comparison
of the estimated region-wide average one-hour area source con-
tribution and the highest observed annual average concentra-
tion in the Chicago AQCR. For the first case, maximizing the
point source impact, the average estimated one-hour NC^ level
from area sources alone is almost equal to the highest observed
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TABLE 4
COMPARISON OF ESTIMATED AVERAGE ONE-HOUR N02
CONCENTRATION DUE TO AREA SOURCES ALONE (FOR ALL MODELED
RECEPTORS) WITH THE HIGHEST OBSERVED ANNUAL AVERAGE
IN 1975 IN THE CHICAGO AQCR
(yg/m3)
Case
Worst Case
Point
Source
Intermediate
Case
Estimated
One-Hour
Average NO-
111
174
Highest
Observed
Annual NO-
109
109
Ratio
1.0
1.5
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-23-
annual average value at any monitor; for the intermediate
case, the estimated area source background is higher by
about 50 percent.
Assuming Chicago to be a reasonable representation of area
source problems in other AQCR's in the country, the highest
observed annual NO- average in an AQCR can be used to represent
the area source contribution to the short-term NO- levels for
meteorological conditions that maximize the point source impact.
For intermediate conditions that result in the overall highest
NO- concentrations, the area source impacts are best reflected by
values 1.5 times the highest observed annual NO- average in an
AQCR.
For meteorological conditions that maximize the area source
impacts, the relationship between the one-hour and the annual
average can also be derived. These are the conditions which
are likely to produce high readings at existing monitors since
in most AQCR's (including Chicago), the monitors are located
to reflect area source influences.* B.ased on the analysis of the
Chicago data, the peak one-hour ambient value from area sources
alone seem to be four to six times the observed annual average
concentrations. Therefore, the 6:1 ratio used in the nationwide
area source analysis appears to be conservative (i.e., on the
high side).
E. Control Options and Cost Analysis
Control strategy development and cost analysis was con-
ducted only for a proposed one-hour NO- standard of 250 yg/m .
The objective here was to compare the control costs estimated
in this detailed analysis with those obtained for Chicago
in the nationwide analysis, and to assess the degree of over
or underestimation in the nationwide control costs.
*See Volume I for further discussion of this issue.
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-24-
The point source control costs and effectiveness data
used in this analysis are the same as described in Volume II of
the nationwide study. No additional area source controls were
considered here. As in the nationwide analysis, a 20 percent
reduction in the area source emissions was introduced to account
for a one percent'annual increase in the VMT and a 25 percent
decrease in the mobile source emissions by 1982 due to mandatory
emission reduction requirements.
«
In the nationwide analysis, point source controls to
achieve a proposed short-term N02 standard at the point of
maximum impact of each source were optimized on a plant basis.
That is, all processes within a plant were evaluated individually
in terms of the cost of emission control per unit improvement in
air quality. Those with the most cost-effective control options
were controlled preferentially so that the desired reduction in
ambient NO- levels at each plant's receptor was achieved in a
least cost manner.
In the Chicago case study, the least cost optimization
routine simultaneously considered all combustors and processes
in Chicago that had a significant impact (>1 ug/m ) at any of
the receptors.* Control cost estimates thus obtained are
theoretically the lowest costs in tKS~shCire AQCR to meet a
specified ambient level at all receptors. The conventional
control strategies (where individual source categories are
required to control to specified levels regardless of their
contribution to the problem) could result in costs several
orders of magnitude higher. This is illustrated by the results
in Table 5 which compares the control costs obtained by the
least-cost and the conventional rollback approaches.**
*Appendix A contains details of the least-cost optimization
model developed for this analysis.
** For a discussion of using economic incentives in N0x
control strategies, see Reference 6.
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TABLE 5
POINT SOURCE CONTROL COSTS TO MEET A ONE-HOUR NO2 STANDARD OF
250 vig/m3 IN CHICAGO AQCR
(CHICAGO CASE STUDY)
Implementation
Strategy
Number of
Sources Contributing
Sources
Controlled
Capital Cost
$106/year
Annual Cost
$106/year
Least-Cost
Rollback
794
794
94
794
131
1651
21
254
i
to
Ln
I
SOURCE: EEA, Inc.
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-26-
Table "6 shows a comparison between the point source con-
trol costs for the Chicago AQCR obtained in the two studies.
The costs are for the 1982 area source growth case: a 20 per-
cent reduction in the area source emissions due to mandatory
mobile source emission standards, a one percent growth in the
VMT, and a ratio of mobile to stationary area source emissions
during the peak hours of 3:1. Point source emissions were
assumed to be the same in 1982 as in 1975.
The cost estimates in the two analyses are remarkably
similar though there are significant differences in the analytical
approaches and the data bases used, as summarized in Table 7 . if
these results can be extrapolated to other AQCR's, then the
results of the nationwide study are probably not seriously biased
toward either systematically high or low estimates.
G. Summary and Conclusions
• NO concentrations from either point or area
Ji
sources can result in high short-term NO-
concentrations. In an urban area, point
sources with short-multiple stacks and
area sources (mobile and dispersed area)
seem to be the dominant cause of high short-
term NO2 concentrations.
• Two distinct groups of point sources can
be identified in terms of their response
(dilution and N02 formation rate) to dif-
ferent meteorological conditions: (1)
plants with high effective plume heights
such as utilities, and (2) plants with a
large number of short stacks such as steel
mills and refineries. The diffusion charac-
teristics of the second point source group
seem to be similar to those of the area
sources.
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-27-
TABLE 6
COMPARISON OF THE CHICAGO AQCR RESULTS OBTAINED IN THE
NATIONAL AND CHICAGO CASE STUDY ANALYSIS
(250yg/m3) N02 STANDARD)
Chicago Case
National Anavsisa' Studv Analysis '
Capital Annual Capital Annual
Cost Cost Cost Cost
(106 $) (106 $) (106 $) (106 $)
123 34 131 21
' Case 4 with a 20 percent reduction in area source
emissions.
Intermediate meteorological conditions with a 20 percent
reduction in area source emissions.
SOURCE: EEA, Inc.
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TABLE 7
MAJOR DIFFERENCES BETWEEN THE NATIONWIDE ANALYSIS
AND THE CHICAGO CASE STUDY
1. Treatment of Point Sources
Nationwide Analysis
Each plant was considered
individually.
The maximum ambient contri-
bution from all sources
within the plant were
summed, irrespective of where
the points of maximum impact
were located.
Chicago Case Study
Interaction of sources
within and among plants
was considered by estima-
ting the ambient contribu-
tion of each at each recep-
tor in a specified network
to
oo
2. Treatment of Area Sources
3. Data Sources
4. Dispersion Model
Ambient contributions were
estimated from the regionwide
highest observed annual average
NO , and incorporated as a
background value.
NEDS Point Source File was used.
PTMAX, a single source model,
was used with no mixing
height limit.
Emissions from area source
grid cells and their impact
on ambient levels were
modelled explicitly
Combination of NEDS and Illinois
EPA files were used, with the
latter updated and allocated on
an hourly basis by Radian Corp.
RAM, a multiple area and point
source model, was used with a
mixing height limit.
SOURCE; EEA, Inc.
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-29-
The meteorological conditions that maxi-
mize the impact of sources with high
effective stack heights are at an opposite
extreme to the conditions that result in
high concentrations from both area sources
or point sources with short effective
stack heights.
An intermediate set of meteorological con-
ditions, closer to the area source maximizing
end on the spectrum of diffusion conditions
seems to result in the highest short-
term NO- concentrations in an urban area.
Little spatial variation is estimated in the
short-term peak NG>2 concentrations due to
area sources.
Under meteorological conditions that
maximize the point source impact, the
area source contribution to the short-
term N02 concentrations in Chicago appear
to be equal to the highest observed
annual average N02 level in the AQCR.
For the intermediate conditions which
result in the highest short-term N02
concentrations overall, the area source
component can be approximated as one and
a half times the highest observed annual
average N02 level.
For conditions which maximize the area
source impact, the estimated peak hourly con-
centrations are from 4 to 6 times the recorded
annual average at the same sites.
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-30-
The least cost NO control options for
X
the Chicago AQCR estimated in (a) the
detailed Chicago Case Study and (b) the
nationwide study are well within ten
percent. There is evidence that the nation-
wide study is probably not seriously biased
toward either high or low estimates.
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-31-
REFERENCES
VOLUME III
1. Epright, B. R., et al, Impact of Point Source Control
Strategies on N02 Levels, Draft Report, Radian Corporation,
February 10, 1978.
2. Aerotherm Division, Control Techniques for Nitrogen Oxides
Emissions from Stationary Sources, Second Edition,
Corporation, December 1977.
3. California Air Resources Board, Control of Oxides of Nitrogen
from Stationary Sources in the Soutn coast Air Basin,ARE
2-1471, California Air Resources Board, September 1974.
4. Environmental Protection Agency Compilation of Air Pollutant
Emissions Factors, (AP-42) Second Edition, August 1977.
5. Memo The Cause of High Short-Term NOg Levels from Robert E.
Neligan, Director of MDAD, USEPA, September 12, 1978.
6. R. J. Anderson, Jr., R. 0. Reid, and E. P. Seskin, An Analysis
of Alternative Policies for Attaining and Maintaining a Short-
Term NOg Standard, prepared for the President's Council an
Environmental Quality, Mathtech, Inc., Princeton, N.J.,
November 14, 1978.
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APPENDIX A
THE EEA LEAST-COST OPTIMIZATION MODEL
In order to calculate the minimum cost of applying NO con-
trol technologies necessary to meet a given ambient air quality
standard for NO-, a heuristic integer program was developed.
I/
The underlying model is a variation of the Knapsack Problem.
In describing the programming problem, the following nota-
tion will be used:
i = an emissions source.
N = total number of sources.
s
t. = control technology applied to source i.
k = technology level.
Klast. = "highest level" of control technology applied
to source i.
j = receptor.
N = total number of receptors.
Hr. = hourly rate of emissions at source i (10 Btu/
hour).
Hours. = total hours of operation per year of source i.
d.. = contribution at receptor j due to source i.
S = ambient air quality standard.
B. = contribution at receptor j due to background
and area sources.
See Senju and Toyoda (1968), Toyoda (1975), and Zanakis (1977)
-32-
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-33-
C , = increase in capital cost rate associated with
i
moving from technology k-1 to technology k at
source i.
OM , = increase in operating and maintenance cost
i
rate associated with moving from technology
k-1 to technology k at source i.
P , = increase in percent of total emissions con-
1 trotled associated with moving from technolo
k-1 to technology k at source i.
A. Control Costs
The annualized cost (AC) to source i of moving from tech-
nology k-1 to technology k is calculated as follows:
AC, . = (.16 C. ,HR. ) + (OM .Hours. Hr.) (1)
tiK tilc 1 t±K i i
Note that the calculation assumes a capital recovery rate of 16
percent per year. Furthermore, it should be noted that capital
costs are a function of Btu's per hour, while operating and
maintenance costs are a function of Btu's per year.
Given equation (1), the total annualized cost (TAG) for
source i to achieve the "highest level" of control technology
can be expressed as follows:
klas^
TAG. = > AC. . (2)
1 f j U » JV
k=0
This is simply the sum- of the increased annualized costs of
applying all control technologies up to and including the
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-34-
"highest level" actually employed. Thus, if klasti = 0, source
i is uncontrolled and the costs of control are assumed to be
zero . '
B. Air Quality
The impact (Impact) of source i on the air quality of the
region can be expressed as a vector of dimension Nr, the number
of receptors. First, we calculate the impact of source i at
receptor j :
klasti
impact di x - k (3)
This states that the impact is represented by the contribution
at receptor j due to source i multiplied by the percentage of
total emissions that remain uncontrolled.
Second, we calculate the ambient air quality (Result) at
receptor j as follows:
Result. = B. + y Impact^. (4)
i = 1
The ambient air quality at receptor j is equal to the background
and area source contributions plus the sum of the impacts of the
individual emissions sources.
The change in air quality (Delta) at receptor j due to
source i associated with moving from technology k-1 to technolo-
gy k at source i can be expressed as:
' Note that klast^ is an integer variable. In the programming
problem, klast^ can take on any integer value between zero
("no control") and five (the assumed "highest level" of
control.
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-35-
Deltaij - dijPt.k 3 = 1 Nr (5)
C. The Problem
With the above information, the problem can be stated as
minimizing the following objective function:
. Ns
TAC^ (6)
i = 1
This is the sum over all sources of the total annualized costs
for controlling each source.
The constraint on the minimization problem can be written
as:
Result. - S 1 0 j = l,...,Nr (7)
This states that the ambient air quality at each receptor must
be less than, or equal to, the ambient standard.
D. The Solution
To begin the program, klast. is set equal to zero for all
sources. This corresponds to no control on all sources. The
Impact and Result vectors are then given by:
Impact^. o di- j = l,...,Nr (8)
Ns
Result. - B. + y> d±. j = l,...,Nr (9)
.
i = 1
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-36-
Thus, the result vector is used to represent the present level
of air quality at each receptor. We then define a limit vector
(Limit) that contains the individual receptor standards. In our
problem, we are assuming one uniform standard, hence:
Limit. = S j = l,...,Nr (10)
Next, we define a vector that represents the difference between
the Result vector and the Limit vector at each receptor and
designate this vector as Extra. This vector represents the
amount by ehich each receptor is in violation of the standard;
it contains no negative entries:
Extra.
Result. - Limit., if Result. > Limit.
0, if Result. < Limit.
(11)
The program then proceeds to pick and apply control techno-
logies to each source in an effort to bring all receptors into
compliance with.the ambient standard. This occurs when the Re-
sult vector lies within the feasible region (see Figure A-l
which depicts a two^jreceptor case) .
Specifically, at each source, the next highest level of
technology is considered. First, the projection (Projection) of
the Delta vector on the Extra vector is calculated:
Nr Delta. Extra.
Projection. = \ ^
1 ^-> Extra.
This gives the total amount that the Extra vector would be
"shortened" if the next "highest level" of technology were
applied to source i (see Figure A-2 ). Since Extra, is a common
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-37-
FIGURE A-l
Diagrammatic Representation of Programming Problem
(Two-Receptor Case)
Impact 4
Limit-
Feasible Region
FIGURE A-2
Projection of the Delta Vector on the Extra Vector
in Programming Problem
Limit.
Limit
1
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-38-
tenn in all the projection calculations , it can be removed.
This leaves simply the dot product (Dot) of the Delta vector and
the Extra vector:
Nr
Dot. = Delta. Extra. (13)
i f ^ 3 D
j - 1
Finally, we define the gradient vector (G) as:
Gi - ^t.k/^i (14)
This expression represents the relative cost of shortening the
Extra vector by a unit when the next "highest level" of control
technology is applied to source i. Once a gradient is calculated
for each source, the lowest one is chosen and applied. This pro-
cess is repeated until one of two possible outcomes occurs:
• The Extra vector equals zero; or
• The "highest level" of control technologies
has been applied to all sources.
If the first occurs, a least-cost solution has been reached. If
the second occurs, the problem is infeasible and no solution can
be found. That is, the standard cannot be met at all receptors
given the available control technologies.
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-39-
REFERENCES TO APPENDIX A
S. Senju, and Y. Toyoda, "An Approach to Linear Programming
with 0-1 Variables," Management Science 15, pp. 196-207
(1968).
Y. Toyoda, "A Simplified Algorithm for Obtaining Approximate
Solutions to 0-1 Programming Problems," Management Science 21,
pp. 1417-1427 (1975).
S.H. Zanakis, "Heuristic 0-1 Linear Programming: An Experimental
Comparison of Three Methods, "Management Science 24, no. 1,
pp. 91-104 (September 1977).
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