United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
ResearchTriangle Park, NC 27711
Research and Development
EPA/600/SR-92/224 January 1993
EPA Project Summary
Review and Evaluation of
Current Methods and User
Needs for Other Stationary
Combustion Sources
David Winkler, David Zimmerman, and Scott Lowe
This report gives results of Phase 1
of an effort to develop improved meth-
odologies for estimating area source
emissions of air pollutants from sta-
tionary combustion sources. The re-
port: (1) evaluates Area and Mobile
Source (AMS) subsystem methodolo-
gies; (2) compares AMS results with
National Emissions Data System
(NEDS) results; (3) describes and evalu-
ates U.S. Department of Energy (DOE)
data sources; (4) confirms user needs;
and (5) gives source characterizations
for kerosene heaters, methane combus-
tion at publicly owned treatment works
(POTWs), and field crude oil consump-
tion. It includes flow charts to describe
how energy consumption is estimated
for DOE's State Energy Data Report.
This Prefect Summary was devel-
oped by EPA's Air and Energy Engi-
neering Research Laboratory, Research
Triangle Park, NC, to announce key find-
ings of the research project that is fully
documented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Area source emissions of total sus-
pended particulate matter (TSP), sulfur di-
oxide (SO2), oxides of nitrogen (NOX),
reactive volatile organic compounds
(VOCs) and carbon monoxide (CO) are
estimated annually by the National Air Data
Branch (NADB) of the U.S. Environmental
Protection Agency (EPA). Categories com-
prising the group "other stationary com-
bustion" include residential, commercial/
institutional, and industrial fuel-burning
sources that are not otherwise treated as
point sources in the Airometric Information
and Retrieval Systems (AIRS) Facility Sub-
system (AFS) or State Implementation Plan
(SIP) inventories.
Historically, the National Emissions Data
System (NEDS) has been the computer
system used by the EPA to calculate, store,
and retrieve area and mobile source emis-
sions for the following criteria pollutants:
TSP, SO2, NOX, VOC, and CO. EPA is in
the process of designing and developing a
new data subsystem in the AIRS called the
Area and Mobile Source (AMS) Subsystem,
which will replace NEDS.
The stationary source combustion cat-
egories are generally recognized as the
"old" NEDS area source categories 01
through 20. For this effort, waste disposal
combustion and other miscellaneous com-
bustion sources have been included. The
waste disposal categories encompass on-
site incineration and open burning (NEDS
categories 21 through 26), and the other
miscellaneous combustion categories in-
clude forest fires, prescribed burning, agri-
cultural burning, orchard heaters, and
structural fires (NEDS categories 60
through 64). Residential wood combustion
is not included in the other stationary source
combustion category for this effort.
SIP inventory guidance and methods
are used to support emissions estimates
and resulting air quality assessments for
areas not meeting National Ambient Air
Quality Standards. Inventory results are
also being used to support control strategy
development, primarily for VOC. Forthcom-
ing SIPs may control NOX, CO, and par-
ticulate matter less than ten urn in diameter
uS) Printed on Recycled Paper
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(PM-10), with more emphasis on combus-
tion sources.
Historically, a significant level of effort
has been required to collect and process
data used to generate the emissions esti-
mates for categories which, collectively,
contribute relatively small emissions mag-
nitudes on both national and local scales.
In addition, the algorithms currently used
to calculate these emissions are based on
data sources and methods that were de-
veloped In the early 1970s. Some of the
methods can be difficult to implement and
require that results be compared and rec-
onciled with other data sources and sub-
sequently recomputed. Many of the
underlying equations which support these
estimation techniques rely on data sources
dating back to the 1960 Census. No at-
tempt to validate the results of these tech-
niques has been made since their
development. EPA's Air and Energy Engi-
neering Research Laboratory (AEERL) has
undertaken a research program to develop
area source methodologies for use in na-
tional and SIP emissions inventory devel-
opment, coordinated under EPA's Joint
Emissions Inventory Oversight Group
(JEIOG). In addition, recent related JEIOG
studies completed by EPA have defined
previously uninventoried area source cat-
egories. Emissions from these categories
may be omitted or underestimated by cur-
rent national and/or SIP methods and are
not included in existing methodologies.
Also, current categories may require finer
resolution (e.g., one category may require
subdividing) to adequately estimate emis-
sions.
A plan was developed to evaluate and
Improve existing area source methodolo-
gies for stationary source combustion. This
plan was structured to:
support ozone/CO SIP inventories,
support national inventories through
NADB,
simplify implementation of categories
recognized as minor emissions
sources, and
provide Increased reliability of esti-
mates where necessary and possible.
This report incorporates the first three
elements of the plan: review of the AIRS/
AMS methodologies and data sources,
evaluation of non-traditional combustion
area sources, and confirmation of the cur-
rent Inventory needs in the user commu-
nity. These elements provide information
to define and evaluate the importance of
each category for methodological simplifi-
cation and development that will be used
to recommend methodological improve-
ments.
In addition, the report reviews current
data and data needs for stationary source
combustion categories, including:
The first review of the draft AIRS/
AMS rnethodologies to identify implicit
differences from NEDS methodolo-
gies, applicability to SIP inventories
and cohsistency with U.S. Department
of Energy (DOE) data sources.
Review of potential, alternative data
sources to support current or poten-
tial areja source methodologies, prin-
cipally 'available from DOE's Energy
Information Agency (EIA).
Confirmation of the needs of the in-
ventory user community for improved
categorization of source categories
and methodologies.
Characterizations of three stationary
source combustion categories that are cur-
rently absent from area source emission
inventories are also included: kerosene
heaters, crude oil combustion in produc-
tion fields, :and methane combustion at
wastewater treatment plants. The absence
of production field crude oil combustion
emissions fpm national inventories has
been a recognized problem since the 1985
National Acid Precipitation Assessment
Program (NAPAP) inventory, and this sec-
tion contains a critical review of a potential
source of arjnual state-level crude oil con-
sumption. Methane combustion at waste-
water treatment plants was pursued while
investigatinc) potential industrial process
gas area source emissions. Although no
industrial sources were identified, meth-
ane consumption as a primary or second-
ary fuel at iwastewater treatment plants
had not been characterized previously.
Review of Current Methods,
Data, and User Needs
The NEDS area source emissions esti-
mation methodologies, developed in the
mid-1970s, Were used with only minor
changes through 1990. Since the replace-
ment of NEDS by AIRS, the AMS sub-
system has been in development to replace
the NEDS ar£a source estimation process.
AMS methodologies have been docu-
mented and; will support the AIRS/AMS
mainframe national component capability.
Evaluation of AMS vs. NEDS
Methodologies
Discussion of the NEDS methodolo-
gies is divided into three sections. The first
portion briefly describes the general AMS
area source estimation process and high-
lights methodological differences and prob-
lems between the former NEDS and current
AMS area source methodologies. The sec-
ond section compares NEDS and AMS
consumption and emissions estimates for
one data set based on the two sets of
methodologies, with particular attention to
the consumption estimates that differ on
the basis of methodological changes. The
third section presents the results of a re-
view of the State Energy Data Report
(SEDR), other fuel and energy documents
from the DOE/EIA, and other government
and private groups that may provide useful
information for the review and/or improve-
ment of current methods.
In general, the AMS methodologies re-
viewed for this task were similar to the
NEDS methodologies. No new research
has been conducted to date to improve
area source methodologies, and the AMS
methodologies are not the result of new
information or analyses. Changes made
during the development of AMS have been
based on two factors:
Simplification of data gathering or
computation processes to recognize
data availability concerns.
Subdivision of NEDS categories to
create more specific individual cat-
egories in AMS.
The review is structured to briefly de-
scribe the category (or category group)
and the logic of the estimation procedure.
The review focused on fuel consumption,
rather than emissions, because the major
function of the methods is to estimate and
allocate fuel use prior to the application of
emission factors and to facilitate the later
comparison of NEDS and AMS results.
The AMS methodological evaluation is
based on five factors:
Internal methodological assumptions.
Availability and currentness of re-
quired data.
Applicability to SIP inventories and
relation to extant SIP guidance.
Relative emissions significance of
each category.
Other factors including surrogate ac-
tivity indicators and emission factors.
Fundamentally, AMS methodologies are
similar to NEDS methodologies. Key
changes are the division of natural gas
consumption into boilers and engines and
the explicit separation of liquefied petro-
leum gas (LPG). State-level data sources
are identical.
In the case of natural gas, NEDS previ-
ously handled the split between boilers
and engines by weighing the emission fac-
tor based on the point source distribution
of natural gas use by boilers and engines.
AMS makes this split explicit and does not
rely on the point source population to act
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as a surrogate for area sources. The split
is critical due to the drastically different
emission profiles of the two sources, espe-
cially for NOX. In AMS, industrial gas con-
sumption (as defined by DOE) is assigned
entirely to boilers, except for the compo-
nent calculated as feedstock. (The method
for calculating feedstock remains the same.)
Lease and pipeline fuels (DOE categories)
are assumed to be used only in engines.
Because NEDS and AMS methodolo-
gies for solid waste and other miscella-
neous combustion and data sources are
identical, there was no need for compara-
tive analyses of these categories.
Description and Evaluation of
DOE Data Sources
The move to use DOE/ElA's SEDR to
support AMS methodologies introduces a
new data source for development and re-
finement of area source methods. The
SEDR report, which summarizes informa-
tion contained in the State Energy Data
System (SEDS), provides national- and
state-level fuel and energy consumption
estimates by major end-use categories.
The underlying delivery or sales statistics
(called series by DOE) are contained in
SEDS; only the summary statistics are
published in SEDR. Much of the data pre-
sented in SEDR and stored in SEDS origi-
nate from the DOE/EIA reports that were
previously used for the NEDS and are still
used in AMS to some extent. Because the
AMS area source fuel and emissions esti-
mates form the basis for many SIP meth-
ods, support national inventory efforts, and
will inevitably be compared to their NEDS
predecessors for trend-type analysis, a
clear derivation of the SEDR estimates
and their relation to their NEDS counter-
parts is necessary.
The advent of AMS and the 1990 Clean
Air Act Amendments (CAAA) have pro-
vided the opportunity and necessity to re-
view the current data sources. Since the
initiation of the NEDS methodologies in
the 1970s, new DOE/EIA publications have
appeared regularly and on a special basis.
Some of these publications may furnish
new information relevant to current area
source categories.
For example, SEDR is an annual DOE/
EIA publication of consumption (physical
units) estimates by state and major end-
use sector. Annual data are typically up-
dated and available within 18 months of
the end of the study year. The consump-
tion data are intended to be as consistent
as possible with other DOE/EIA publica-
tions. Although SEDR reports consump-
tion, these estimates generally assume that
consumption in a calendar year is equiva-
lent to fuel sales or distribution in that year.
SEDR relies on many other DOE/EIA forms
and publications as its basis. The principal
data sources include the following reports
and EIA forms by fuel:
Coal
Quarterly Coal Report and Form EIA-
759 (utilities only).
Natural Gas
Natural Gas Annual.
Petroleum
Petroleum Supply Annual and Fuel
Oil and Kerosene Sales Report (data
from the Petroleum Supply Annual
are adjusted for annual changes in
stocks).
AMS groups fuel consumption into the
categories listed in Table 1. The area
source categories are defined, in large
measure, by the DOE data sources that
form the basis of the state consumption
estimate. SEDR defines these sectors as:
Table 1. Other Stationary Fuel Combustion Categories
Residential: Private primary and sec-
ondary residences, including single
family, multifamily, mobile homes, and
summer homes. Institutional housing
such as schools, barracks, and hos-
pitals are classified as commercial.
Commercial: Businesses not engaged
in transportation or manufacturing or
other types of industrial activity are
designated as commercial. SIC codes
used for these establishments are 50
through 87, and 89 through 97. (SC
88 applies to residential units.)
Industrial: Manufacturing, mining, con-
struction, agriculture, fisheries, and
forestry operations/facilities are clas-
sified as industrial. Corresponding
SICs are 01 through 39.
NEDS Area Source
Classification Code3
(SCC)
Category Description
001
002
003
004
005
(AMS)
006
007
008
009
010
011
(AMS)
012
013
014
015
016
017
018
(AMS)
(AMS)
019
020
Residential Fuel - Anthracite Coal
Residential Fuel - Bituminous Coal
Residential Fuel - Distillate Oil
Residential Fuel - Residual Oil "
Residential Fuel - Natural Gas
Residential Fuel - LPG
Residential Fuel - Wood'
Commercial/Institutional Fuel - Anthracite Coal
Commercial/Institutional Fuel - Bituminous Coal
Commercial/Institutional Fuel - Distillate Oil
Commercial/Institutional Fuel - Residual Oil
Commercial/Institutional Fuel - Natural Gas
Commercial/Institutional Fuel - LPG
Commercial/Institutional Fuel - Wood"
Industrial Fuel - Anthracite Coal
Industrial Fuel - Bituminous Coal
Industrial Fuel - Coke "
Industrial Fuel - Distillate Oil
Industrial Fuel - Residual Oil
Industrial Fuel - Natural Gas
Industrial Fuel - Natural Gas- Boilers
Industrial Fuel - Natural Gas - Engines
Industrial Fuel -Wood11
Industrial Fuel - Process Gas "
Categories included in AMS but not in NEDS are indicated.
* Emissions are considered insignificant; estimates are not calculated for these categories.
c Residential wood combustion was excluded from this review.
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User Needs
EPA representatives, academic re-
searchers, environmental groups, and en-
vironmental consulting firms were asked to
characterize emission inventory users'
needs. This information was reviewed to
determine the respondents' reported needs
for developing methodologies to estimate
emissions from other stationary combus-
tion sources. Several EPA personnel from
the Office of Air Quality Planning and Stan-
dards (OAQPS) ware contacted in a tele-
phone survey to identify the needs of users
contacting these offices with questions
about stationary combustion area source
emissions. The EPA personnel were also
asked to discuss any relevant ongoing re-
search into these sources to reduce the
potential for duplication of effort.
The following source categories, identi-
fied in the survey, are addressed in the
report:
Waste Disposal
Wildfires
Wood Combustion/Wood Stoves
Prescribed Burning
Forest Slash Burning
Agricultural and Biomass Burning
Asphalt Roofing Kettles
Firefighting Training
Gas and Oil Wellhead Flaring
Industrial Combustion
Natural Gas Combustion
Non-utility Fuel Burning
Utility Boilers
Orchard Heaters
Residential Coal Combustion
Source Characterization
Several previously uninventoried source
categories that have been recently identi-
fied and characterized are included in this
report: kerosene heaters, methane com-
bustion at publicly owned treatment works
(POTWs), and field combustion of crude
oil.
Kerosene Heaters
Kerosene heaters are typically used as
a supplemental heat source in areas in
which 1} residential central heating sys-
tems are not installed, 2) adequate heat is
not available, and/or 3) temperatures are
extremely jcold. Kerosene heaters usually
supplement other heating sources such as
electric, fuel oil, and gas furnaces. Por-
table kerosene heaters are limited to
supplemental heating because the kero-
sene tank on each heater is too small to
provide continuous heating without con-
stant refilling. Table 2 lists two of the most
popular kerosene heater sizes and some
of their features.
Table 2. Kerosene Heater Characteristics
Tank Fuel
Size Output Size Consumption
Rate (Btufar)* (gal.)" (gaUhr)*
Small
Large
9,000
23,000
0.98
1.6
0.075
0.17
1 gal.» 0.0038m3;
1 gal./hr =,0.0038 rrf/hr
In the past 17 years, there has been a
dramatic increase in kerosene heater us-
age, possibly caused by the increased op-
erating expense for central heating
systems. In [1974, only 3,400 portable heat-
ers were sold in the U.S. By 1979, the
market had increased to sales of 4 million
heaters annually. Current estimates place
today's annual sales of kerosene heaters
at between 1400,000 and 1,000.000 units,
with approximately 4.8 million heaters cur-
rently in use in the U.S. Overall, 17 million
heaters have been sold in the U.S. Kero-
sene heater usage is most common in the
Northern U.S. and least common in the"
Southwest U.S.
f
Publicly Owned Treatment
Works ;
Publicly^ owned treatment works
(POTWs) using anaerobic digestion to sta-
bilize sludge generate a digester gas. This
gas, chiefly methane, can be used as a
primary or supplemental fuel, or can be
flared to the atmosphere. The methane
gas is a natural by-product of the anaero-
bic bacterial digestion process practiced in
wastewater treatment plants. The amount
of gas generated is related to many vari-
ables in the system, including waste com-
position, temperature, residence time,
previous treatment steps, and degree of
nitrification (ire., the conversion of ammo-
nia to nitrate). When the gas is collected
from the digester tanks, it is typically used
within the plant as fuel. An estimate of the
methane derived from the sludge digestion j
process is presented in the report.
Crude Oil Consumption in Field \
Operations
Research into the information contained
in the SEDR and the DOE Petroleum Sup-
ply Annual has led to the discovery of
information that may be useful in separat-
ing and reporting consumption and emis-
sions of crude oil in field operations.
Historically, this segment was not estimated
in NEDS and was not tracked by DOE
databases used for NEDS. California, how-
ever, was known to report crude consump-
tion data for NEDS in the residual oil)
category. This reporting in turn affected
comparisons of residual oil consumption;
between NEDS and DOE. This created a
particular problem in the 1985 NAPAP da-
tabase, where these comparisons quali-
fied the reliability of the NEDS data.
Study of the SEDR and investigation of
the basis of its estimates has identified a
potential source for the crude oil data miss-
ing from previous (EIA) data sources. Use
of the data for emissions inventories in the
future depends on:
Crude consumption is not currently
counted in the EIA residual oil esti-
mates that form the state-level pub-
lished estimates to which AMS is
normalized, or the crude consump-
tion can be separated.
The number derived in this fashion
truly represents all crude oil con-
sumed.
Consumption can be allocated to the
state and county level.
Point source components can be iden-
tified and subtracted.
Discussion of Results
The report contains a detailed review
of the current national methodologies for
the estimation of emissions for the "other
stationary fuel combustion" categories. In
addition, a review of the current DOE data-
bases is included in this report, as well as
a discussion of the user needs for im-
provements in the other stationary fuel
combustion categories.
Several previously uninventoried source
categories that have been recently identi-
fied and characterized are included in this
report: kerosene heaters, methane com-
bustion at POTWs and field combustion of
crude oil.
U.S. Government Printing Office: 1993 750-071/60190
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D. Winkler, D. Zimmerman. andS. Lowe are with TRC Environmental Corp., Chapel
Hill, NC 27514. , ^
£ Suo Ktmbrough Is the EPA Project Officer (see below).
The complete report, entitled''Review-and Evaluation of Current Methods and User
Needs for Other Stationary Combustion Sources," (Order No. PB93-127801/AS;
Cost: $27.00; subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
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
Official Business
Penalty for Private Use
$300
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