United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-88/106 Oct. 1989
ŁEPA Project Summary
Area Source
Documentation for the 1985
National Acid Precipitation
Assessment Program Inventory
Janice L. Demmy, Wienke M. Tax, and Thomas E. Warn
EPA's Office of Air Quality Planning
and Standards (OAQPS) has develop-
ed a nationwide data base of esti-
mated air pollutant emissions from
point and area sources known as the
National Emission Data System
(NEDS). Point source emissions es-
timates for every plant are submitted
annually by each state to EPA for re-
view. Area source data files devel-
oped from the NEDS system will
serve as the basis for the 1985
NAPAP area source emissions inven-
tory. However, to date, NEDS area
source data have been developed
mainly by OAQPS with data volun-
tarily submitted by State agencies.
This report provides, to states and
other participants and users of the
1985 NAPAP Emissions Inventory, a
general understanding of the esti-
mating procedures that will be used
by NAPAP and OAQPS to generate
1985 emissions estimates for area
source categories. General methodol-
ogy and assumptions are discussed
as well as the original source of
algorithms, activity levels, and
emission factors.
Emission estimates are updated
annually by a series of computer pro-
grams which multiply each current
area source activity level by an
emission factor that accounts for
emissions removed by any control
technology. County emissions esti-
mates are then summed to produce
national emissions estimates.
For this report, area sources are
divided into stationary sources, mo-
bile sources, solid waste disposal,
miscellaneous area sources, and ad-
ditional area sources. Additional area
sources Includes categories for
which methodologies have been de-
veloped to estimate emissions for the
1985 NAPAP Emissions Inventory that
are not part of the current NEDS Area
Source Categories.
This Protect Summary was devel-
oped by EPA's Air and Energy
Engineering Research Laboratory, Re-
search Triangle Park, NC, to announce
key findings of the research project
that Is fully documented In a separate
report of the same title (see Protect
Report ordering information at back).
Introduction
The USEPA's Office of Air Quality
Planning and Standards (OAQPS) has
developed a nationwide data base of
estimated air pollutant emissions from
point and area sources known as the
National Emission Data System (NEDS).
Point source emissions estimates for
every plant are submitted annually by
each state to EPA for review. Area source
data files developed from the NEDS
system will serve as the basis for the
1985 NAPAP area source emissions
inventory. However, to date, NEDS area
source data have been developed mainly
by OAQPS with data voluntarily sub-
mitted by State agencies.
This report provides, to state and other
participants and users of the 1985
NAPAP Emissions Inventory, a general
understanding of the estimating proce-
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dures that will be used by NAPAP and
OAQPS to generate 1985 emissions
estimates for area source categories.
General methodology and assumptions
are discussed as well as the original
source of algorithms, activity levels, and
emission factors necessary to calculate
emissions for each area source in NEDS.
The report presents methodologies for
all identified sources not defined as point
sources in a specific geographic region.
Area sources include all mobile sources,
and stationary sources too small, difficult,
or numerous to classify as point sources.
Area sources are divided into five major
groups: stationary fuel combustion,
mobile sources, solid waste disposal,
miscellaneous area sources, and addi-
tional area sources. Additional area
sources include categories for which
methodologies have been developed to
estimate emissions for the 1985 NAPAP
Emissions Inventory that are not part of
the current NEDS Area Source Cat-
egories. Activity level and emission factor
methodologies used to produce
emissions estimates are presented for
each area source within the above
groups.
Discussion
Activity levels are derived primarily
from related information published by
other Federal agencies, supplemented by
special data developed by EPA for the
purpose of developing NEDS area source
inventories. Published data (e.g., fuel use
by state, motor vehicle miles of travel by
state and county, and forest fire acres
burned by state) are used with related
data (e.g., employment, population, and
miscellaneous geographic or economic
data) to derive annual county estimates
of the activity levels for each NEDS area
source category. The activity levels
derived are adjusted to account for point
source activity (e.g., fuel use by point
sources) so that the area source data
reflect only the activity levels (and
resulting calculated emissions) that are
not accounted for by point sources.
Area source emissions estimates for
five pollutants (particulates, SOX, NOX,
VOCs, and CO) are calculated for each
area source category utilizing appropriate
emission factors, contained in the NEDS
area source emission factor file. For
many categories, the same emission
factors are used for all counties; however,
for some source categories, state or
county specific emission factors account
for local variables that affect emissions.
The more specific emission factors are
used in NEDS calculations for all highway
motor vehicle categories, fugitive dust
categories, and selected other categories
in a few counties where data are available
to develop more applicable emission
factors than the national emission factors.
Provision is also made to override
computer-calculated emissions with
hand-calculated emissions that may be
more accurate than any simple emission
factor calculation.
Emissions estimates are updated annu-
ally by a series of computer programs
which multiply each current area source
activity level by an emission factor that
accounts for emissions removed by any
control technology. County emissions
estimates are then summed to produce
national emissions estimates.
Stationary Sources
Stationary sources are divided into
three major fuel categories: Residential,
Commercial and Institutional, and
Industrial. Each category is further
subdivided into fuel types for which
consumption data are estimated using
algorithms and published fuel use data.
For each of the above categories, con-
sumption data are multiplied by emission
factors to obtain emissions estimates.
The residential fuel category estimates
emissions for residential activities which
utilize fuel for water heating, space
heating, and cooking. Emissions contri-
buted by residential fuel consumption are
determined for six fuel types using algori-
thms which consider heating degree
days, number of residential units, and
median number of rooms per dwelling.
For each estimated fuel type, county ac-
tivity levels are then normalized with
published state data.
Area source emissions from fuel use
by commercial and institutional sources
include emissions from hospitals, hotels,
laundries, schools, and universities. Con-
sumption data for each of five fuel types
are obtained in the following steps: (1)
estimating total county fuel consumed by
the five identified commercial categories,
(2) distributing total fuel consumption by
the subcategories to each fuel type, (3)
determining state total commercial area
source fuel consumption, (4) normalizing
estimates against published state con-
sumption, and (5) determining and
allocating county consumption by "other"
commercial categories.
Emissions generated by the industrial
sector which are not accounted by point
source categories are calculated for four
fuel types: bituminous coal, distillate oil,
residual oil, and natural gas. County fuel
consumption is estimated by multiplying
county employment figures for Standai
Industrial Classification (SIC) categoric
20 through 39 by a fuel intensity facto
Results are then normalized wil
published state values.
Mobile Sources
Mobile sources that contribute to are
source emissions are divided int
Highway Vehicles, Off-Highway Vehicle
Railroad Locomotives, Aircraft, an
Marine Vessels.
Highway vehicles are disaggregate
into four categories on the basis of us
and gross vehicle weight for the purpos
of calculating consumption. The categ<
ries include light duty gasoline vehicle
light duty gasoline trucks, heavy dul
diesel vehicles, and heavy duty gasolir
vehicles. NEDS utilizes vehicle typ
registration data and published averag
miles traveled by each vehicle type 1
allocate consumption to the county lev*
Fuel consumption, average fuel effic
encies, and road type mileage in eac
county are used to determine vehic
miles traveled (VMT) for three roa
classes: limited access roads, rural road
and urban roads. Emission factoi
obtained from the execution of
computer simulation model are applied 1
determine emissions for vehicle type ar
speed class.
Emissions from off-highway vehicle
are generated by activities of gasolir
and diesel vehicles which do not utilii
road systems. Vehicles contributing 1
off-highway emissions are divided into s
general categories: farm equipment, coi
struction equipment, industrial equi(
ment, motorcycles, lawn and garde
equipment, and snowmobiles. Consumi
tion is estimated separately for eac
category by either apportioning nation
fuel consumption to counties on the bas
of employment, population, etc., or calc
lating county or state totals by applyir
national fuel consumption rates I
average usage figures and equipme
populations. Emission factors ai
weighted for each category using equij
ment populations. Off-highway moto
cycle emissions are computed usir
emission factors from a computer mod
for uncontrolled vehicle emissions.
The activity level for railroad loci
motive use of distillate oil is calculated t
allocating published state consumptk
data to the county level based on coun
population statistics. Fuel consumptk
data are used with emission factors
determine emissions.
Activity level calculations for aircrs
(private, military, and commercial) utili;
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aircraft operations data and plane type
populations to estimate number of
landing/takeoff cycles (LTOs) in each
group. Emission factors are defined as
emissions per LTO.
Marine vessel consumption of distillate
oil, residual oil, and gasoline is deter-
mined by adjusting published consump-
tion data. County allocation of distillate
and residual oil consumption by vessels
utilizes home port location for registered
boats and port tonnage handled for the
remaining boat population. Gasoline
vessel consumption computations utilize
inboard and outboard boat registration
and published average consumption data
to determine consumption. County allo-
cation is based on inland water area,
coastline, and the number of months
suitable for recreational boating. Emission
factors are applied to consumption data
to obtain emissions estimates.
Solid Waste Disposal
The area source category for solid
waste disposal includes on-site refuse
disposal activities by residential, com-
mercial/institutional, and industrial sec-
tors. Solid waste generation in hundreds
of tons is used as a measure of activity
level for burning and on-site incineration.
This is multiplied by specific emission
factors to obtain emissions estimates.
Miscellaneous Area Sources
NEDS area sources which are not
defined by the first three categories are
compiled in the miscellaneous area
sources category. The importance of
these area categories is that, while total
emissions from each source are relatively
small compared to the major categories,
emissions at a particular time may be
significant. Methodologies are presented
for the following: Gasoline Marketed,
Organic Solvent Consumption, Unpaved
Road Travel, Unpaved Air Strip Use.
Land Tilling, Forest Wildfires, Managed
Burning, Agricultural Burning, and
Structural Fires.
In brief, activity levels, measured using
category specific data, are multiplied by
emission factors to obtain emissions
estimates. Activity levels for Gasoline
Marketed are determined using county
retail service station sales data. Activity
levels for Organic Solvent Consumption
are determined by allocating national
estimates of organic solvent consumption
by end use category to counties
according to manufacturing employment
data or population. The Unpaved Road
Travel category utilizes vehicle miles
traveled (VMT) and rural population for
the basis of allocation. Unpaved Airstrip
Use is measured by landing/takeoff (LTO)
cycles. Number of acres burned and fuel
loading factors are used to measure
activity levels for Forest Wildfires,
Managed Burning, and Agricultural
Burning. The Structural Fires category
utilizes the number of building fires to
allocate to the county level.
Additional Area Sources
The 1985 NAPAP inventory will provide
detailed county level VOC emissions
estimates for additional area sources
which previously have not been included
in the NEDS area source categories.
Alliance methodologies developed for the
1985 NAPAP inventory are presented for
the following area sources: Publicly
Owned Treatment Works (POTWs);
Hazardous Waste Treatment, Storage,
and Disposal Facilities (TSDFs); Fugitive
Emissions from Synthetic Organic
Chemical Manufacturing; Bulk Terminals
and Bulk Plants; Fugitive Emissions from
Petroleum Refining Operations; Process
Emissions from Bakeries, Pharmaceut-
ical, and Synthetic-Fiber Manufacturing;
Crude Oil and Natural Gas Production
Fields; and Cutback Asphalt Paving
Operations. For most categories, national
VOC emissions estimates are allocated to
the county level using category-specific
data such as industrial flow and
production figures. Activity levels, emis-
sion factors, and control efficiencies are
used to determine emissions for the
remaining sources.
Conclusions
Emissions estimates for each area
source category are computed and up-
dated annually by a series of hand
calculations and computer programs
described by specific area source
methodologies. In general, the current
activity level for each area source is
multiplied by the appropriate emission
factor and a factor which accounts for
any emission control technology
employed. Activity level estimation pro-
cedures involve the manipulation of state-
supplied data and/or information
published by Federal agencies with
special data developed by OAQPS to
develop the NEDS area source inven-
tories. Emission factors and control data
for most categories are obtained from the
EPA/OAQPS publication Compilation of
Air Pollutant Emission Factors - Volume I:
Stationary Point and Area Sources (AP-
42). For this report, area sources are
divided into three primary groups:
stationary fuel combustion, mobile
sources, and solid waste disposal. NEDS
Area Source Categories which do not fit
the above categories are classified as
miscellaneous area sources. Additional
area sources include categories for which
methodologies have been developed to
estimate emissions for the 1985 NAPAP
inventory that are not part of the current
NEDS Area Source Categories.
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Janice L Demmy, Wienke M. Tax, and Thomas E. Warn are with Alliance
Technologies Corp., Chapel Hill, NC 27514.
tee Beck is the EPA Project Officer (see below).
The complete report, entitled "Area Source Documentation for the 1985 National
Acid Precipitation Assessment Program Inventory," (Order No. PB 89-151
427/AS; Cost: $28.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Q 2B
Official Business
Penalty for Private Use $300
EPA/600/S8-88/106
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