United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/SR-94/139 December 1994
EPA Project Summary
Economic Growth Analysis
System: Version 2.0
Terri Young, Randy Randolph, and Daniel Bowman
The two-volume report describes the
development of, and provides informa-
tion needed to operate, the Economic
Growth Analysis System (E-GAS)
model. The model will be used to project
emissions inventories of volatile organic
compounds (VOCs), oxides of nitrogen
(NOX), and carbon monoxide (CO) for
ozone nonattainment areas and Re-
gional Oxidation Model (ROM) model-
ing regions.
The report details the design and de-
velopment of E-GAS and includes de-
tailed descriptions of the workings of
the E-GAS computer modeling software
components and external software.
The system is an economic and ac-
tivity forecast model that translates the
user's assumptions regarding regional
economic policies and resource prices
into Source Classification Code (SCC)
level growth factors. The report pro-
vides E-GAS users with sufficient back-
ground information to define and cali-
brate the E-GAS model, as well as the
procedures and syntax necessary to
operate the system. The organization
of the user's manual is determined by
the process used in operating the sys-
tem, providing images of sample
screens as well as text.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that is fully docu-
mented in two volumes (see Project
Report ordering information at back).
Introduction
On November 15, 1990, the Clean Air
Act Amendments (CAAA) of 1990 were
signed into law. The CAAA require that
extreme, severe, serious, and multi-state
moderate ozone non-attainment areas use
photochemical grid modeling to demon-
strate future attainment with the ozone
national ambient air quality standard
(NAAQS) [Section 182(e)(2)(A)]. In addi-
tion to photochemical grid modeling, the
CAAA require that moderate, serious, se-
vere, and extreme ozone non-attainment
areas submit rate-of-progress (ROP) in-
ventories demonstrating a 15% reduction
in emissions from 1990 to 1996
[Section 182(b)(1)(A)]. Further, ROP inven-
tories for serious, severe, and extreme
areas must include demonstration of a
3% reduction (averaged over 3 years) from
1996 until attainment is achieved
[Section 182(c)(2)(B)].
Section 182(b)(1)(A) of the CAAA speci-
fies that the 15% reduction from baseline
emissions accounts for any growth in emis-
sions after 1990. A key component of the
ROP inventories and photochemical grid
modeling demonstrations will be the de-
velopment of credible growth factors for
the existing inventories.
Since growth in source emissions largely
depends on the amount of economic ac-
tivity growth in an area, a consistent set of
growth factors requires forecasts using
consistent Gross National Product (GNP)
forecasts and a consistent methodology
for estimating economic activity in Urban
Airshed Model (UAM) and Regional Oxi-
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dant Model (ROM) modeling regions. The
need for consistent economic growth fac-
tors, however, must be satisfied in a way
that allows states to use their own esti-
mates of national and regional economic
activity. The Economic Growth Analysis
System (E-GAS) is an economic and ac-
tivity forecast model which satisfies both
of these standards.
The existing inventories for ROP dem-
onstration and photochemical modeling will
be housed in the Aerometric Information
Retrieval System (AIRS). E-GAS can be
applied to AIRS inventories for the devel-
opment of emission projections to 2010,
when extreme areas must reach attain-
ment. State users can create custom GNP
forecasts and may modify input assump-
tions for the regional models in the E-
GAS system. The system also allows EPA
users to develop volatile organic compound
(VOC), nitrogen oxide (NOx), and carbon
monoxide (CO) growth factors using a
single GNP forecast, providing baseline
emission growth estimates for comparison
with growth factors submitted by the states.
The nonattainment areas modeled were
chosen on the basis of their nonattainment
designation. All serious, severe, and ex-
treme areas were modeled, as were multi-
state moderate areas. These areas, their
designations and area definitions, were
announced in the November 6, 1991, Fed-
eral Register.
To minimize both the number and run
time of the models in E-GAS, eight mod-
els were developed. Separate models were
developed for EPA Regions 1, 4, 5, 6, 7,
and 9. In addition, models were devel-
oped that combine the areas in EPA Re-
gions 2 and 3 and EPA Regions 8 and 10.
Each model includes all extreme, severe,
serious, and multi-state moderate areas,
as well as each state and partial state in
the region.
E-GAS is a menu-driven system that
guides the user through a series of screens
which collect information for adapting the
model to the user's needs. User input is
limited to selecting menu items and set-
ting parameters by entering data in text
boxes.
The E-GAS modeling system contains
three tiers. Tier 1 includes available na-
tional economic forecasts which are used
to drive the regional economic models;
Tier 2 includes regional economic models
for the UAM modeling areas, as well as
the states in the ROM modeling regions;
and Tier 3 estimates fuel consumption,
physical output, and Vehicle Miles Trav-
eled (VMT) based on Tier 2's regional
economic forecasts. The tiers must be
sequentially executed, since data are cre-
ated by and passed from early tiers for
transfer to later tiers. The three-tiered struc-
ture of E-GAS allows users flexibility in
modeling. While tiers must be run before
proceeding to later tiers, the system al-
lows the models to be rerun at the user's
discretion. For example, users may run a
variety of national models before perform-
ing regional modeling on the last national
model run.
The National REMI Model allows the
user to create a national-level growth pro-
jection. It is Tier 1 of the three-part pro-
cess of creating estimated growth factors;
it generates data to drive the Regional
REMI Model (Tier 2). This tier may be
rerun any number of times before pro-
ceeding to Tier 2. Five national forecasts
are available: Bureau of Labor Statistics
(BLS), Data Resources, Inc. (DRI), Re-
search Seminar in Quantitative Econom-
ics (RSQE), Wharton Econometric Fore-
casting Associates (WEFA), and user-en-
tered Gross National Product (GNP) Data.
The Regional REMI Model allows the
user to develop a regional growth simula-
tion. This is Tier 2 of the three-part pro-
cess of creating estimated growth factors;
it generates data to drive the Growth Fac-
tor Module (Tier 3). In the E-GAS model,
more than 100 regular economic policy
variables, translator variables, and popu-
lation variables can be adjusted. Chang-
ing these variables allows the user to simu-
late the economic impact of anticipated
government policy changes, market
changes, or other exogenous changes to
the regional economy. These variables are
accessed from the REMI EDFS-14 model
and offer scenarios for changes in tax
rates (corporate profit tax, equipment tax,
investment tax, personal income tax, and
property tax), costs (including relative pro-
duction cost, import cost, and export cost),
wage rate, employment transfer payments,
purchasing power, and final demand. This
tier may be rerun any number of times
before proceeding to Tier 3.
The Growth Factor Module is the third
tier where growth factors are generated
and written to files in the \EGAS
subdirectory. This module translates
changes in the economic activity levels of
the most recent regional forecast to growth
factors for physical output, fuel consump-
tion, and VMT. These growth factors will
be developed for two-, three-, and four-
digit Standard Industrial Classification (SIC)
levels, depending on available data for
developing and disaggregating the fac-
tors. These
SIC-level growth factors will be matched
with SCC codes. The user is given a
choice of file formats as either the Emis-
sion Preprocessor System (EPS) format
or an ASCII text file. The file is output by
year, county level, and SCC code.
E-Gas Reference Manual
The Reference Manual provides back-
ground information on the design, devel-
opment, and implementation of the E-GAS
system, as well as information concerning
the execution of the system itself. Chapter
1 provides an overview of the system as
well as discussions of basic system de-
sign and development considerations.
Chapter 2 discusses the CAAA require-
ments related to the use of photochemical
grid modeling in demonstrating future
NAAQS attainment and the submission of
rate of progress plans that will demon-
strate how an area will achieve the 15%
reduction in VOC emissions by 1996 vis-
a-vis the use of E-GAS. Chapter 3 dis-
cusses the current EPA emissions projec-
tion guidance and its relationship to E-
GAS. Chapter 4 explains the role and use
of national and regional economic fore-
casts in E-GAS. Chapter 5 discusses how
fuel choice is forecast within E-GAS. Chap-
ter 6 discusses how electric utility genera-
tion is estimated within E-GAS. Chapter 7
discusses how physical output is estimated
within E-GAS. Chapter 8 explains the
methodology used within E-GAS to fore-
cast vehicle miles traveled. Chapter 9 ex-
plains, CROSSWALK, the final compo-
nent of E-GAS. CROSSWALK assigns
growth factors from the other E-GAS mod-
ules to point, area, and mobile SCC's.
Appendix A lists the data used to develop
electric utility generation estimates. Ap-
pendix B lists the parameter values by
state used in the electric utility module
within E-GAS. Appendix C lists the Bu-
reau of Labor Statistics codes and SCC
matches within CROSSWALK. Appendix
D provides an example of the CROSS-
WALK output files.
E-Gas User's Guide
The User's Guide can be used to pilot
the user through the E-GAS system. Chap-
ter 1 introduces the terminology used with
the system as well as the syntax and
format of the program and user guide.
Chapter 2 discusses the use of E-GAS by
explaining the logical progression of the
program, presenting sample screens, pro-
viding explanations of input formats, and
describing the E-GAS utilities found
throughout the system. Chapter 3 de-
scribes the role of national economic mod-
els in E-GAS and the five options avail-
able to the user. Chapter 4 explains the
general function of E-GAS's policy vari-
ables; it then describes the specific vari-
ables while explaining their input. Chapter
5 describes the role of model suppres-
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sions in E-GAS and describes all sup-
pressions available to the user. Chapter 6
describes the operation of and data re-
quired for the E-GAS National Model (Tier
1). Chapter 7 provides similar descriptions
of the Regional Model (Tier 2), and Chap-
ter 8 describes Tier 3, the Growth Factor
Module. Chapter 9 identifies contacts for
further information regarding the opera-
tion of E-GAS and the logic of the system.
Basic Hardware Requirements
The program has been designed for an
IBM-compatible personal computer envi-
ronment. The system requires the follow-
ing minimum hardware configurations:
IBM 80386 or 100% compatible
personal computer
Math coprocessor
580 Kilobytes of Conventional
Memory
100 Megabytes of available fixed
disk storage
VGA graphics capabilities
DOS 5.0 or higher
5.25 or 3.5 in. floppy disk drive
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T. Young, R. Randolph, and D. Bowman are with TRC Environmental Corp., 6320
Quadrangle Dr., Suite 100, Chapel Hill, NC 27514.
Sue Kimbrough is the EPA Project Officer (see below).
The two-volume report, entitled "Economic Growth Analysis System: Reference
Manual, Version 2.0; and User's Guide, Version 2.0," includes paper copy and
eight sets of floppy disks (Order No. PB95-501961/AS; Cost: $360.00; subject to
change).
The set 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
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/600/SR-94/139
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