APPENDIX B

EMISSIONS MODELING FOR THE DFW ATTAINMENT 

DEMONSTRATION SIP REVISION FOR THE 2008 EIGHTHOUR OZONE STANDARD
APPENDIX B: EMISSIONS MODELING FOR THE DFW 

ATTAINMENT DEMONSTRATION SIP REVISION FOR THE 

2008 EIGHT-HOUR OZONE STANDARD

TABLE OF CONTENTS

Appendix B: Emissions Modeling for the DFW Attainment Demonstration SIP Revision for the 

1997 Eight-Hour Ozone Standard ...................................................................................................1

1. General Modeling Emissions Development............................................................................ 2

1.1 Base Case Modeling Emissions....................................................................................... 2

1.2 Baseline Modeling Emissions ......................................................................................... 4

1.3 Future Year Modeling Emissions ................................................................................... 4

1.4 Future Year Control Strategy and/or Sensitivity Analyses Emissions ........................... 4

2. Point Source Modeling Emissions Development .....................................................................5

2.1 2006 Base Case Point Source Modeling Emissions Development................................. 6

2.1.1. Texas Point Sources .......................................................................................... 6

2.1.2. Regional (Outside of Texas) Point Sources......................................................21

2.1.3. Plume-in-Grid (PiG) Source Selection............................................................ 30

2.1.4. Summary of June 2006 Base Case Point Sources .......................................... 30

2.2 2006 Baseline Point Source Modeling Emissions Development ..................................31

2.2.1. Texas Point Sources .........................................................................................31

2.2.2. Outside Texas.................................................................................................. 32

2.2.3. Summary of 2006 Baseline Point Sources ..................................................... 33

2.3 2018 Future Year Point Source Modeling Emissions Development ............................ 34

2.3.1. Regulations and the Cap-and-Trade Programs ...............................................35

2.3.2. Attainment Areas of Texas.............................................................................. 39

2.3.3. Nonattainment Areas (NAA) of Texas ............................................................ 44

2.3.4. 2018 Regional (Outside of Texas) Point Sources............................................ 49

2.3.5. Offshore, Mexico, and Canada.........................................................................52

2.3.6. Summary of Future Case Point Source Data Files...........................................52

2.4 2018 Point Source Control Strategy and/or Sensitivity Analyses .................................53
3. On-Road Mobile Source Modeling Emissions Development.................................................53

3.1 On-Road Mobile Source Emissions Inventories for 10-County DFW...........................53

3.2 On-Road Mobile Source Emissions Processing.............................................................57

3.2.1. Texas Low Emission Diesel Fuel Benefits ...................................................... 58

3.3 10-County DFW Photochemical Modeling Input..........................................................59

3.4 Attainment Demonstration Motor Vehicle Emissions Budget......................................61

3.5 On-Road Mobile Source Emissions Inventories for Non-DFW Areas ......................... 66

4. Non-Road, Off-road, And Area Source Modeling Emissions.................................................67

4.1 Oil and Gas Production and Drilling Emission Inventory Development......................67

4.2 Airports .........................................................................................................................80

4.3 Locomotives .................................................................................................................. 85

4.4 Non-Road/TexN ............................................................................................................91

4.5 Area Sources ................................................................................................................103

5. Biogenic Modeling Emissions .............................................................................................. 112

5.1 Emission Factor and PFT Inputs ................................................................................. 112

5.2 Fractional Vegetated Leaf Area Index Input ............................................................... 112

5.3 Meteorological Input ................................................................................................... 112

5.4 Biogenic Emission Summary....................................................................................... 112

6. References............................................................................................................................. 116

1. GENERAL MODELING EMISSIONS DEVELOPMENT

The EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment 

of Air Quality Goals for Ozone, PM2.5, and Regional Haze (EPA, 2007) specifies a procedure for 

demonstrating attainment through modeling. Instead of using the model results in an absolute 

sense, the eight-hour ozone procedure uses the modeling results in a relative sense. This relative 

approach is based on how the model responds to the reduction in emissions between a baseline 

and a future year. Therefore, the photochemical modeling process for attainment demonstration 

requires four modeling emissions data sets:

• base case emissions;

• baseline emissions;

• future year emissions; and

• future year control strategy and/or sensitivity analyses emissions.

1.1 Base Case Modeling Emissions

In order for the photochemical model to be used in the attainment demonstration, the model 

needs to be capable of adequately replicating historical episodes (base cases) for which high 

daily eight-hour ozone was measured. To maximize model performance, base case emission 
inputs are estimated as accurately as possible. In the development of the base case modeling 

emissions, a number of quality assurance techniques are used to evaluate the reasonableness of 

the emission magnitudes, along with their spatial distribution and temporal profile. Using the 

quality assured episode-specific emissions along with other modeling inputs (e.g., meteorology), 

the photochemical model is run and the simulated concentrations of both ozone and ozone 

precursors of nitrogen oxides (NOX) and volatile organic compounds (VOC) are compared to the 

measured concentrations to evaluate the adequacy of the photochemical model in replicating the 

base case. If the evaluation indicates that the base case is not adequately replicated, then 

diagnostics are conducted to determine which modeling inputs are unsatisfactory. When the 

emissions are implicated, the modeling emissions are reviewed and pertinent revisions are made 

as appropriate. If the evaluation implicated other inputs, or once the photochemical model 

adequately replicates the base case, then the modeling emissions are considered to be 

sufficiently representative of the episode.

A summary of the primary data sources for the development of the base case modeling 

emissions is provided in Table 1-1: Summary of Base Case Point Source Emission Data Sources, 

Table 1-2: Summary of Base Case On-Road Mobile Source Emission Data Sources, and Table 

1-3: Summary of Base Case Non-Road Mobile, Area, Oil and Gas, and Biogenic Source Emission 

Data Sources.

Table 1-1: Summary of Base Case Point Source Emission Data Sources

Region Data Source

Texas 2006 State of Texas Air Reporting System (STARS)

Regional 2008 National Emissions Inventory (NEI) based EPA Modeling Platform

All States 2006 EPA Clean Air Markets Division (CAMD) Air Markets Program Data (AMPD) 

hourly data

Harris County 2006 hourly Harris County Tank Landing Loss surveys

HGB 2006 HGB Highly Reactive Volatile Organic Compound (HRVOC) reconciliation

Offshore 2005 Bureau of Ocean Energy Management (BOEM) Gulf-Wide Emissions 

Inventory (GWEI) platforms of western Gulf of Mexico

Mexico 1999 Phase III Mexico National Emissions Inventory 

Canada 2006 National Pollutant Release Inventory (NPRI)

Table 1-2: Summary of Base Case On-Road Mobile Source Emission Data Sources

Region Data Source

DFW 2006 based on MOVES2010a and local travel demand model (TDM) for vehicle 

miles traveled (VMT)

Other Texas 2006 based on MOVES2010b and Highway Performance Monitoring System 

(HPMS) for VMT

Outside Texas 2006 based on MOVES2010b default analyses

Table 1-3: Summary of Base Case Non-Road Mobile, Area, Oil and Gas, and 

Biogenic Source Emission Data Sources

Region Non-Road Mobile 

Sources Area Sources Oil and Gas Sources Biogenics

Texas Texas NONROAD 

(TexN) model 2008 TexAER

2008 TexAER, 2006 

Texas Railroad 

Commission data

MEGAN 2.1 model
Region Non-Road Mobile 

Sources Area Sources Oil and Gas Sources Biogenics

Outside 

Texas 2006 NMIM 2008 EPA NEI 2008 EPA NEI MEGAN 2.1 model

Emissions modelers generally use a hierarchical approach, such that the closer the area is to the 

nonattainment area of interest, the more detailed the resolution of the emissions, i.e., Canadian 

emissions are expected to have very little influence on model performance in DFW, so the TCEQ 

does not attempt to gather hourly power plant emissions from Canada. Emissions are developed 

for the ozone precursors of NOX, VOC, and carbon monoxide (CO). The emission inventories 

(EIs) are prepared for photochemical modeling input using Version 3 of the Emissions 

Processing System (EPS3)1

.

1.2 Baseline Modeling Emissions

The EPA procedure for demonstrating attainment requires the development of modeling 

emissions for a baseline year to be used with similarly developed future year emissions. In order 

to keep the baseline and future year modeling emissions commensurate, more generic nonepisodic ozone season day (OSD) emissions are developed for the baseline year. The OSD 

modeling emissions for the baseline and future years are developed using the same averaging 

and estimating procedures, which provides an appropriate basis for assessing the photochemical 

model response to emission reductions.

The major difference between the base case and baseline modeling emissions is the treatment of 

the hourly-specific emissions for elevated point sources, such as electric generating units 

(EGUs). Emissions for the other source categories are identical between the base cases and 

baseline modeling emissions. 2006 was chosen as the baseline year and Section 2.2 describes 

the averaging processes used in the development of the baseline inventory.

1.3 Future Year Modeling Emissions

The 10-county DFW area is classified as moderate nonattainment under the 2008 eight-hour 

ozone standard. The attainment date for DFW is December 31, 2018 and the modeling 

attainment year is 2018. Modeling emissions for the 2018 future year were estimated by 

applying growth projections, existing control measures, and emissions caps to the baseline (in 

general) modeling emissions. The 2018 modeling emissions include the benefits of the Federal 

Motor Vehicle Control Program (FMVCP), Ellis County Cement Kiln Cap, Mass Emissions Cap 

and Trade (MECT) Program, the Highly Reactive VOC Emission Cap and Trade (HECT) 

Program in the Houston-Galveston-Brazoria (HGB) area, and Phase II of the Clean Air 

Interstate Rule (CAIR).

1.4 Future Year Control Strategy and/or Sensitivity Analyses Emissions

Existing controls with compliance dates that have passed or are between the baseline and the 

future years are modeled in the future case identified above. Any new control strategies, other 

rules, potential rules, or sensitivity analyses that are modeled are applied on top of the future 

case modeling in order to determine the efficacy in the future. The point source sensitivity 

analyses performed for this DFW attainment demonstration are a 

 1 Environ product, maintained by Environ
Discrete Emission Reduction Credit (DERC) Flow Control sensitivity and a Cross State Air 

Pollution Rule (CSAPR) sensitivity. See Section 2.4 2018 Point Source Control Strategy and/or 

Sensitivity Analyses of this appendix for details.

2. POINT SOURCE MODELING EMISSIONS DEVELOPMENT

Much of the point source emissions development began where the December 2011 DFW SIP 

Revision2 left off, with this SIP Revision providing large upgrades to the TCEQ Modeling 

Platform as described in Chapter 3 of this SIP Revision, including new and extended modeling 

domain definitions that include the entire continental U.S. (CONUS), new versions of the 

Comprehensive Air Quality Model with Extensions (CAMx) and Version 3 of the Emissions 

Processor System (EPS3), and the updated Carbon Bond 6 (CB6) chemical mechanism. The two 

modeled episodes of the 2006 base case (“June” and “AQS1”) were originally modeled in the 

March 2010 HGB SIP Revision3 , and then upgraded for the TCEQ Rider 84 Modeling Platform, 

which is equivalent to this DFW Modeling Platform. Some of the descriptions of this DFW 

modeling development will refer to the work performed for the SIP Revisions noted above and 

footnoted (for proper reference), especially for descriptions of HGB-specific emissions 

development, and will hereafter be referred to as “previous SIP documentation.”

The various data sources that went into the development of the point source modeling emissions 

are summarized in Table 2-1: Sources of Point Source Emissions Data. The TCEQ compiled and 

formatted the data to generate modeling datasets for the base case, the baseline, and the future 

case studies as detailed in subsequent sections.

Table 2-1: Sources of Point Source Emissions Data

Sources of Data Calendar Year(s) 

Used

TCEQ State of Texas Air Reporting System (STARS) 2006, 2012

TCEQ Hourly Floating Roof Tank Landing Loss (TLL) Surveys 2006

TCEQ-derived Highly Reactive Volatile Organic Compound (HRVOC) 

Reconciliation using Potential Source Contribution Factor (PSCF) 

Methodology

2006

EPA Clean Air Markets Division (CAMD) Air Markets Program Data

(AMPD) of power plant Continuous Emissions Monitors (CEMs) for all 

states

2006, 2013

EPA/TCEQ Clean Air Interstate Rule (CAIR) allocation estimates for 

entire modeling domain 2018

Electric Reliability Council of Texas, Capacity, Demand, and Reserve

report

2014

U.S. Department of the Interior, Bureau of Ocean Energy Management 

(BOEM) Gulf-Wide Emissions Inventory (GWEI) of Offshore Platforms 2005, 2008

EPA Emissions Modeling Clearinghouse (EMCH) Modeling Platform 2008, 2018

 2 December 7, 2011 DFW Attainment Demonstration for the 1997 Eight-Hour Ozone Standard at 

http://www.tceq.texas.gov/airquality/sip/dfw_revisions.html

3 March 10, 2010 HGB Attainment Demonstration for the 1997 Eight-Hour Ozone Standard at 

http://www.tceq.texas.gov/airquality/sip/HGB_eight_hour.html#AD

4 TCEQ program to support local air quality planning for the ozone NAAQS at 

http://www.tceq.texas.gov/airquality/airmod/rider8
Sources of Data Calendar Year(s) 

Used

Environment Canada National Pollutant Release Inventory (NPRI) 2006

Phase III Mexico National Emissions Inventory and future case 

projection 1999, 2018

2.1 2006 Base Case Point Source Modeling Emissions Development

The following subsections describe development of the base case point source modeling 

emissions for all portions of the domain used for the June 2006 and August-September 2006

(AQS1) DFW modeling episodes.

2.1.1. Texas Point Sources

For Texas point sources, ozone season daily (OSD) emissions data from State of Texas Air

Reporting System (STARS) and hourly emissions data from the EPA’s Air Markets Program 

Data (AMPD) provided the basis for modeling the 2006 base case episode. Additionally, the

supplemental “extra olefins” file was used from previous SIP Revisions to account for reconciled 

highly reactive volatile organic compound (HRVOC) emissions in the HGB area. HRVOC 

include ethylene, propylene, 1,3-butadiene, and all isomers of butene. The episode-specific 

survey results of HGB floating roof tank landing losses (TLL) were used to develop files of 

hourly emissions for the 2006 episode. The following subsections describe the development of 

modeling emissions for each of these components.

2.1.1.1. State of Texas Air Reporting System (STARS)

Point source emissions and industrial process operating data are collected annually from sites 

that meet the reporting requirements of 30 Texas Administrative Code (TAC) §101.10. Subject 

entities are required to report levels of emissions subject to regulation from all emissionsgenerating units and emissions points, and also must provide representative samples of 

calculations used to estimate the emissions. Descriptive information is also required on process 

equipment, including operating schedules, emission control devices, abatement device control 

efficiencies, and emission point discharge parameters such as location, height, diameter, 

temperature, and exhaust gas flow rate. All data submitted in the annual emissions inventory 

questionnaires (EIQ) are subjected to TCEQ quality assurance (QA) procedures. The data are 

then stored in the STARS database. The TCEQ reports point source emissions data to the EPA 

for inclusion in the National Emissions Inventory (NEI).

Annually, the TCEQ collects emissions information from approximately 2000 major point 

sources. In nonattainment areas, major point sources are defined for inventory reporting 

purposes as industrial, commercial, or institutional sources that emit actual levels of criteria 

pollutants at or above the following amounts: 10 tons per year (tpy) of volatile organic 

compound (VOC); 25 tpy of nitrogen oxides (NOX); or 100 tpy of any of the other criteria 

pollutants including carbon monoxide (CO), sulfur dioxide (SO2), 10-micron threshold 

particulate matter (PM10), or lead (Pb). For the attainment areas of the state, any company that 

emits a minimum of 100 tpy of any criteria pollutant must submit an inventory. Additionally, 

any source that either generates or has the potential to generate at least 10 tpy of any single 

Hazardous Air Pollutant (HAP) or 25 tpy of aggregate HAPs is required to report emissions to 

the TCEQ. The reporting requirements, guidance documents, trends, and summaries of the 

most recently quality assured year of reported data can be found on the TCEQ Point Source 

Emissions Inventory website at 

http://www.tceq.state.tx.us/implementation/air/industei/psei/psei.html.
Development of the Texas point source emission modeling files began with queries of the 

quality-assured data of the STARS database. Updated modeling query reports are typically run 

when significant STARS updates are completed. The STARS modeling extract report (“STARS 

extract”) is simply a snapshot of Texas emissions, since emissions from previous years can be 

updated by the regulated entities.

SAS computer programming code was written, updated, and/or modified to parse the STARS 

extract, perform various logical checks and comparisons, assign defaults for missing data, apply

rule effectiveness to VOC paths with control devices, and format the data into an AIRS Facility 

Subsystem (AFS) file that can be processed with the modules of EPS3.

The STARS extract contains four types of emission rates: annual, OSD, emission events (EE), 

and scheduled maintenance startup and shutdown (SMSS). When supplied, the OSD emissions 

in tons per day (tpd) are modeled, plus any EE/SMSS for the source (after conversion to tpd).

When OSD is not provided by the source, an OSD is computed from the reported summer use 

percentage of the source and the other reported operational parameters of the source, plus any 

reported EE/SMSS for the source. The modeled OSD emission rate is representative of average 

daily emissions during the summer. For 2006, the ozone season for emission inventory (EI)

reporting purposes is June through August. This is generally the time of the year that monitored 

ozone concentrations are highest. An example of STARS extract data is available in the March 

2010 HGB SIP Appendix B, Section 2.1.1.

2.1.1.2. Rule Effectiveness (RE)

The TCEQ continue to apply RE to the STARS VOC emissions where appropriate, as a legacy 

procedure. The purpose is to account for the possibility that not all facilities covered by a rule 

are in compliance with the rule 100% of the time and that control equipment does not always 

operate at its assumed control efficiency. Additional details about rule effectiveness and how it is 

applied by the TCEQ are described in previous SIP documentation.

2.1.1.3. Preparation of AFS File for EPS3 Input

The resultant OSD AFS file is in a format ready for input to EPS3. The STARS-derived AFS file 

for all criteria pollutants typically has more than 200,000 records. Each point source emissions 

path contains references for the TCEQ account (RN), equipment (FIN), and exhaust point 

(EPN). For ozone modeling purposes, values for the ozone precursors of NOX, VOC, and CO are 

retained in the AFS file for EPS3 input. An example AFS record with explanations, specific QA 

steps, and file naming conventions can be found in previous SIP documentation. The AFS file 

format used by the TCEQ for this modeling, including field descriptions and options, which is an 

expansion of the standard EPS3 AFS format, can be found on the TCEQ FTP modeling webpage,

ftp://amdaftp.tceq.texas.gov/pub/TX/ei/basecase/point/AFS/AFS-EPS3-v3.docx.

2.1.1.4. Preparation of Photochemical Model-Ready Files with EPS3

EPS3 is used to process the emissions in the AFS file into a format ready for photochemical 

model input. Photochemical model inputs require that the emissions be (in EPS3 order 

performed by the TCEQ):

• chemically speciated into groups of compounds with similar reactivity for the formation of 

ozone;

• temporally allocated by hour of day, day of week, etc.; and

• spatially allocated to grid cells or assigned to fixed points.
The EPS3 User’s Guide5 provides additional details for processing the point source emissions for 

photochemical model input. The remainder of this section discusses some of the specific point 

source emissions processing procedures. Excerpts of the data, which provide a better visual 

understanding of the processes, can be found in previous SIP documentation.

2.1.1.4.1. Chemical Speciation with EPS3

VOC emissions in STARS can be reported as individual compounds, mixtures, classes of 

compounds, total VOC, and unclassified VOC. The VOC values that are included in the AFS file 

are speciated into carbon bond groups of similar ozone reactivity that will be recognized by the 

specific chemical mechanism of the photochemical model. For operational efficiency, most 

photochemical modeling studies are not based on separate algorithms for each individual 

reaction. Instead, for SIP modeling purposes, groups of compounds with similar reactivity for 

the formation of ozone are grouped together and input into the photochemical model. The TCEQ 

used the CB6 “lumped” chemical mechanism, implemented via EPS3 module SPCEMS.

The majority of TCEQ EIQ responses include constituent VOC emission rates, which are used to 

develop point-specific speciation profiles. When the composition of the VOC reported for a 

specific source is unknown or not fully-speciated, the default speciation profile is applied based 

on the source classification code (SCC) and the default speciation from EPA’s SPECIATE6

database software program. More detail on the TCEQ source-specific speciation approach is 

available in previous SIP documentation and in an international emission inventory conference 

paper7

.

Ethane and acetone, which are technically not VOCs by EPA’s definition, are also extracted from 

STARS and processed in the emissions model, and are subjected to the same speciation as all of 

the other STARS compounds. Ethane, acetone and VOC are now included in VOC totals in tables 

and tile plots in subsections below, because the photochemical model can use these compounds 

as CB6 lumped species categories of their own. This is a new procedure for TCEQ that was 

brought about by CB6 implementation. Because ethane and acetone are additive to the VOC, the 

modeled and tabulated VOC will almost always be greater than reported (STARS) VOC. The 

Tank Landing Losses and Extra Olefins datasets were created prior to this new procedure, so 

those datasets do not include ethane or acetone.

2.1.1.4.2. Temporal Allocation with EPS3

Even though OSD is typically used for processing of photochemical modeling emissions, EPS3 

can temporally distribute emissions by month, day of the week, and hour of a specific episode 

when sufficient detail is provided in the EIQ. Previous SIP documentation provides detail about 

temporal allocation, along with examples of the cross reference and profile records.

2.1.1.4.3. Spatial Allocation with EPS3

Photochemical models generally rely on a three-dimensional Eulerian system in which

emissions are allocated to individual grid cells. Emissions occur at or near the surface for most 

 5

 Written and updated by Environ to accompany their software. The TCEQ posts a courtesy copy at 

ftp://amdaftp.tceq.texas.gov/pub/TX/ei/basecase/point/eps3/EPS3UG_UserGuide_200908.pdf

6

 http://www.epa.gov/ttn/chief/software/speciate/

7

 Thomas, et al, Emissions Modeling of Specific Highly-Reactive Volatile Organic Compounds (HRVOC) 

in the Houston-Galveston-Brazoria Ozone Nonattainment Area, EPA-sponsored 17th Annual International 

Emission Inventory Conference, Portland, Oregon, June 2008. 

Paper: http://www.epa.gov/ttn/chief/conference/ei17/session6/thomas.pdf

Presentation: http://www.epa.gov/ttn/chief/conference/ei17/session6/thomas_pres.pdf
source categories such as area, biogenic, some on-road mobile, and some non-road mobile, and 

are classified as low-level, being released at the same time, mixed throughout the grid cell.

Numerous point sources also fall into the low-level source category, but large combustion 

sources, such as power plants, are categorized as elevated sources, because their hot exhaust 

gases can rise several hundred meters into the atmosphere.

Low-level point sources are allocated to grid cells and merged with the other low-level source 

categories prior to photochemical model input. Whereas, elevated point sources are kept at their 

reported X-Y locations and assumed to emit from the calculated effective plume height of Z to 

better simulate physical mixing in the elevated layers of the photochemical model. As with other 

advanced emissions processors, EPS3 processing of point source emissions is divided into lowlevel and elevated streams, which provides better simulation of how elevated emissions are 

distributed prior to mixing and reacting with surface emissions. The drawbacks of using the dual 

regimes are more complicated EPS3 processing and longer photochemical model run times.

The photochemical model inputs for point sources consist of a single low-level gridded merged 

file and a single file of elevated sources. A plume cutoff height of 30 meters was chosen to divide 

the point sources into low-level and elevated categories. The emissions from elevated sources 

can be individually tracked, and NOX reaction chemistry can be enhanced by treating these 

plumes as Lagrangian puffs by use of the optional Plume-in-Grid (PiG) treatment. The TCEQ 

uses the Greatly Reduced Execution and Simplified Dynamics (GREASD) PiG option8 in CAMx, 

which is most applicable to large NOX plumes. More detail on the GREASD PiG approach is 

provided below in Section 2.1.3.

Figure 2-1: Tile Plot of DFW 10-County OSD Non-EGU Low-Level NOX Emissions for June 1, 

2006 is a tile plot of the low-level OSD (non-EGU) NOX emissions for the DFW ten county area 

at the 4 km by 4 km grid cell resolution. The specific day of the episode is irrelevant for OSD 

emissions, because each modeled day of OSD emissions is identical. Figure 2-2: Tile Plot of 

DFW 10-County OSD Non-EGU Elevated NOX Emissions for June 1, 2006 is a plot of the 

elevated OSD (non-EGU) NOX emissions for the DFW 10-County area. Note that a vast majority 

of the NOX emissions are from elevated sources (mainly combustion with hot exit gas and taller 

stacks). Also note that the diurnal profiles of the OSD sources are generally flat (don’t vary 

across the day) on average, indicating that the non-EGUs are dominated by sources that operate 

continuously.

 8

 See Environ’s CAMx User’s Guide at http://www.camx.com/download/default.aspx
Figure 2-1: Tile Plot of DFW 10-County OSD Non-EGU Low-Level NOX Emissions 

for June 1, 2006
Figure 2-2: Tile Plot of DFW 10-County OSD Non-EGU Elevated NOX Emissions for 

June 1, 2006
2.1.1.5. Hourly Air Markets Program Data (AMPD)

To enhance emissions accuracy for the base case, the TCEQ increases temporal resolution by 

replacing some of the daily OSD emission records with as much monthly, daily, or hourly data9

as available. For the electrical generating units (EGU) in the state, hourly records from the 

EPA’s AMPD database are substituted for the STARS OSD records. “AMPD” refers to EGU

(a.k.a. power plants) emissions in which a continuous emission monitoring (CEM) system must 

be used to record and store emissions data. “AMPD” is an updated database name for what 

TCEQ has previously referred to as “Clean Air Markets Division (CAMD)” data or “Acid Rain 

Data (ARD).” This substitution occurs simultaneously removing the AMPD source from the OSD 

files while adding hourly records for the source to the AMPD file, to avoid any double counting 

of emissions.

Under the Clean Air Act’s Acid Rain Program and the other budget/cap programs for EGUs,

each unit reports its emissions of SO2, NOX, and CO2, along with other parameters such as heat 

input. The EPA quality assures the raw hourly data and provides datasets and a query wizard on 

the AMPD website10 for downloading the data. Missing or invalid hourly data that arise from 

CEM equipment problems are generated by the EPA using specific substitution criteria. Thus, 

EGU-reported data (such as input to STARS or the NEI) do not always match that from EPA’s 

AMPD.

Hourly data were downloaded from EPA’s AMPD website for Texas and the rest of the country

for the 2006 episodes. The AMPD database uniquely identifies point sources by FACILITY 

ID/ORIS (Office of Research Information Systems) number and UNIT ID/BLRID (boiler 

identification). FACILITY ID/ORIS identifies the site and UNIT ID/BRLID specifies the source

(piece of equipment generating the emissions, not to be confused with the stack, which is the 

exit point of the emissions to the atmosphere) within the site. The TCEQ maintains an internal 

cross reference that links the FACILITY ID and UNIT ID emissions data to a NEI and STARS

FIPS/plant/stack/point emissions “path” which provides location, stack, and other parameters 

needed to model the point source. Corresponding hourly VOC and CO records for sources

matched with the cross reference were generated using their VOC-to-NOX and CO-to-NOX

ratios. This was still the procedure for the 2006 work. In later work for this SIP, the TCEQ 

upgraded this procedure by basing the hourly VOC and CO emissions on the hourly heat input 

instead of the hourly NOX emissions. AFS files with “ARD” in the name contain these hourly 

emission records, although in later work, the designation has been changed to “AMP” to more 

accurately reflect the data source. Previous SIP documentation describes, in more detail, with 

examples, how ARD/AMPD point sources are converted to hourly AFS emissions records.

Figure 2-3: Tile Plot of DFW 10-County AMPD EGU NOX Emissions for June 6, 2006 is a tile 

plot of AMPD NOX emissions of the 10-County DFW area for June 6, 2006. The tile plot is used

to graphically QA the modeled emissions. Reported on the tile plots are the emissions totals by 

county in the lower left hand corner and the

corresponding total diurnal profile of the sources in the lower right corner of the graphic. The 

colored/shaded tiles represent the quantity of emissions within that grid cell. A colored/shaded 

 9

 Thomas, et al, Development of an Hourly Modeling Emissions Inventory from Several Sources of 

Regulatory Speciated Hourly Data for the Houston-Galveston-Brazoria Ozone Nonattainment Area, EPAsponsored 17th Annual International Emission Inventory Conference, Portland, Oregon, June 2008. 

Poster Presentation: http://www.epa.gov/ttn/chief/conference/ei17/poster/thomas.pdf

10 http://ampd.epa.gov/ampd/
tile represents the AMPD EGU NOX tons for a modeled day’s 4 km-by-4 km grid cell within the 

10-County DFW area.

Figure 2-4: Tile Plot of DFW 10-County AMPD EGU NOX Emissions for June 14, 2006 is a tile 

plot similar to Figure 2-1, except that it represents a day in the June episode that has fewer EGU 

emissions. Note that the tabulated June 14 NOX emissions are approximately 1.5 tons lower than 

the June 6 NOX emissions for the 10-County EGUs. Also note from the diurnal profile that the 

maximum hourly emissions total for June 14 occurs during the hour beginning at 3:00 PM at a 

level of approximately 0.52 tons per hour. Whereas, the diurnal profile for June 6 has a lower 

low NOX tons per hour and a higher high NOX tons per hour, with the maximum (approximately 

0.75 tons per hour) shifted to the 4:00 PM hour. The comparison of Figure 2-3 and Figure 2-4

points out the variability of the overall DFW EGU emissions, even within the same month.

Figure 2-5: Tile Plot of Texas AMPD EGU NOX Emissions for August 31, 2006 is a tile plot of the 

entire AMPD NOX emissions for August 31, 2006, during the AQS1 episode. This day is one of 

the days that recorded some of the highest ozone at most of the DFW area monitors. Note that to 

cover the entire state, Figure 2-3 grid cell size is 12 km. Also note that the baseload (run almost 

continuously) EGUs in the remainder of Texas flatten out the diurnal profile a bit compared to 

the peaking or intermediate units in the DFW area.
Figure 2-3: Tile Plot of DFW 10-County AMPD EGU NOX Emissions for June 6,

2006
Figure 2-4: Tile Plot of DFW 10-County AMPD EGU NOX Emissions for June 14,

2006
Figure 2-5: Tile Plot of Texas AMPD EGU NOX Emissions for August 31, 2006
2.1.1.6. 2006 Tank Landing Loss (TLL) Survey in HGB

As a result of a Texas Air Quality Study II (TexAQS II) remote sensing VOC project in July 2005, 

large storage tanks in specific service (e.g., tanks-for-hire at terminal facilities and crude oil 

breakout stations) in the Houston Ship Channel (HSC) area were found to be landing their 

floating roofs (internal and external) on the tank legs and not reporting those vapor space losses.

As a result, a TCEQ Chapter 115 rule was written that limits the number of permissible 

“convenience” roof landings, and additional VOC emissions from special inventory surveys 

specific for these events were added to the sources that replied to the survey. Additional details 

about the under-reported VOC emissions and data development for modeling are in the March 

2010 HGB SIP Appendix B, Section 2.1.1.7.

Figure 2-6: Tile Plot for HGB Tank Landing Loss Surveys for a Representative Summer Day in 

2006 in 2006 is a tile plot of a representative day of the TLL that was added to HGB. Note the 

diurnal variation of these emissions.
Figure 2-6: Tile Plot for HGB Tank Landing Loss Surveys for a Representative 

Summer Day in 2006
2.1.1.7. Emissions Inventory Reconciliation in HGB (aka, HRVOC Reconciliation, Extra 

Olefins)

EI Reconciliation is the process by which the reported EI is adjusted so that modeled emissions 

more closely match the concentrations measured at monitors during the episodes. TexAQS II 

confirmed the need for this, as TexAQS 2000 first affirmed. VOC, and especially HRVOC, 

continue to be under-reported in the annual EIQs, according to monitors and aircraft 

measurements. In previous SIP revisions, as with this SIP revision, the TCEQ generated a dayspecific “extra olefins” file to add to each episode day of the modeling EI in HGB to account for 

the under-reporting. Rather than placing the reconciled extra emissions at the locations of 

existing point sources, the TCEQ placed a single pseudo point in each affected modeling cell, 

and assigned an emission rate for each HRVOC to best offset the difference between modeled 

and calculated concentrations, according to the Potential Source Contribution Function (PSCF).

This same file was modeled unchanged. Additional details about the under-reported HRVOC 

emissions, the PSCF technique, and data development for modeling are in the March 2010 HGB

SIP Appendix B, Section 2.1.1.9.

Figure 2-7: Tile Plot of HGB HRVOC Reconciliation Emissions for a Representative Summer 

Day in 2006 is a tile plot of modeled VOC representing the HRVOC reconciliation (PSCFv3).
Figure 2-7: Tile Plot of HGB HRVOC Reconciliation Emissions for a Representative 

Summer Day in 2006
2.1.2. Regional (Outside of Texas) Point Sources

This section and its subsections discuss the point source modeling emissions development for all 

areas outside of Texas within the modeled CAMx domain. The modeled Regional area includes 

the following parts:

• Continental U.S.A. outside of Texas ;

• Offshore (Gulf of Mexico);

• Mexico; and

• Canada.

2.1.2.1. Continental USA Outside of Texas, non-EGU NEI

The 2006 EI for states outside of Texas were developed from EPA’s 2008 NEI based Modeling 

Platform. The TCEQ downloaded the annual emissions inventory data11 from the EPA 

Emissions Modeling Clearinghouse (EMCH) in the Flat File 2010 (FF10) format, a format 

suitable for Sparse Matrix Operator Kernel Emissions (SMOKE) processing. To be consistent 

with the area source data modeled, the 2008 data were used without back-casting to 2006. The 

2008 NEI was used as an upgrade from the 2005 NEI, because the 2008 NEI touted to be a 

more thorough and detailed inventory than the 2005. Records for certain SCCs, for rail and 

airports, were removed to avoid duplicating emissions with area source categories. An AFSformatted file, including all necessary and relevant modeling parameters, was produced for 

EPS3 processing. The associated temporal allocation file for SMOKE was converted to create the 

daily temporal distribution. A June day was selected to represent a typical ozone season day.

Details on AFS file creation from the NEI-based data, including QA, speciation, and temporal 

allocation, are described in previous SIP documentation.

2.1.2.2. States Outside of Texas, Hourly AMPD Substitution for EGUs

The TCEQ replaced the original emission records with hourly records for all the AMPD EGUs in 

all states outside of Texas by matching the AMPD identifiers, ORIS and Unit ID. The TCEQ 

maintains a (ORIS and Unit ID keyed) cross reference that links the 2008-based NEI to the 

AMPD data.

Location and stack parameters, obtained from the NEI are appended to the AMPD point 

sources. All AMPD points in the adjacent states of Louisiana, Arkansas, and Oklahoma are cross 

referenced; thus, AMPD emissions in these states are accurately placed for the model.

Corresponding hourly VOC and CO records for EGUs matched with the cross reference were 

generated using their VOC-to-NOX and CO-to-NOX ratios.

AMPD NOX emissions for the EGUs of the adjacent states for a specific episode day modeled in 

2006 are shown in Figure 2-8: Tile Plot of AMPD EGU NOX Emissions for the Adjacent States 

for June 14, 2006. This is a tile plot of the 12 km by 12 km grid cell domain with Texas in the 

center. Note that the emissions summary in this tile plot is for the entire 12 km domain, minus 

Texas. AMPD NOX emissions for the EGUs of the continental USA outside of Texas for the same 

specific modeled episode day are shown in Figure 2-9: Tile Plot of AMPD EGU NOX Emissions 

for the USA (outside of Texas) for June 14, 2006. This is a tile plot of the 36 km grid cell domain.

 11 The TCEQ extracted the “CAP_BAFM_2008NEI_v2_POINT_20120202_09feb2012_v1” annual 

emissions data file, which does not include Integrated Planning Model (IPM), or EGU, units
Figure 2-8: Tile Plot of AMPD EGU NOX Emissions for the Adjacent States for June

14, 2006
Figure 2-9: Tile Plot of AMPD EGU NOX Emissions for the USA (outside of Texas) 

for June 14, 2006
2.1.2.3. Offshore Point Sources

The TCEQ obtained the 2005 Gulf-Wide Emissions Inventory (GWEI), developed by Eastern 

Research Group (ERG) under contract to the Bureau of Ocean Energy Management (BOEM).

These are the same data modeled and documented in the two previous SIP revisions. The report 

and data are divided into two parts, oil and gas exploration and production platform (point) 

sources, and non-platform (area) sources. The TCEQ obtained the 2005 GWEI data and 

documentation from BOEM12. Previous SIP documentation discusses the formatting of the data, 

QA, justification for using June 2005 as representative data, and creation of temporal profiles.

The offshore emissions are illustrated in Figure 2-10: Tile Plot of Offshore Platform NOX

Emissions for a Representative June day of 2005.

 12 in Microsoft Access (zipped) and PDF format, respectively. These can be downloaded from the BOEM

webpage, http://www.boem.gov/Environmental-Stewardship/Environmental-Studies/Gulf-of-MexicoRegion/Air-Quality/2005-Gulfwide-Emission-Inventory.aspx
Figure 2-10: Tile Plot of Offshore Platform NOX Emissions for a Representative 

June day of 2005
2.1.2.4. Mexican Point Sources

The TCEQ used the data from Phase III of the 1999 Mexico NEI, which is the most current data 

used by EPA and the regional planning organizations (RPO). These are the same data modeled 

and documented in the two previous SIP revisions. The TCEQ downloaded the NIF format 

versions of the files from the EPA North American Emissions Inventory webpage 

(http://www.epa.gov/ttn/chief/net/mexico.html) and parsed the files into AFS files.

The 1999 data were used for the 2006 episode without growth because there is no information 

on growth and controls for Mexican point sources. No temporal allocation or speciation data 

were available, so defaults were used. A tile plot of the Mexican OSD NOX emissions of Phase III 

of the 1999 Mexico NEI for a representative OSD is provided as Figure 2-11: Tile Plot of Mexican 

NEI NOX Emissions for a Day in 1999.
Figure 2-11: Tile Plot of Mexican NEI NOX Emissions for a Day in 1999
2.1.2.5. Canadian Point Sources

The TCEQ obtained 2006 point source emissions from the Canadian National Pollutant Release 

Inventory (NPRI). These data are the first upgrade to the Canadian emissions since the last 

three SIP revisions. The data were provided to the TCEQ in the one-record-per-line (ORL) 

format by staff at Environment Canada. The VOC emissions were developed for the CB05 

chemical mechanism. The TCEQ converted the files to AFS records for further processing with 

EPS3. No temporal allocation or speciation data were available, so defaults were used. The NOX

emissions for this dataset are illustrated in Figure 2-12: Tile Plot of Canadian NPRI NOX

Emissions for a Day in 2006.
Figure 2-12: Tile Plot of Canadian NPRI NOX Emissions for a Day in 2006
2.1.3. Plume-in-Grid (PiG) Source Selection

CAMx provides the option to model selected point sources with a PiG algorithm. NOX reaction 

chemistry is enhanced by treating these selected point source plumes as Lagrangian puffs. The 

TCEQ uses the GREASD PiG option in CAMx, which is most applicable to large NOX plumes.

The GREASD PiG option was used for all point sources that met the criteria in Table 2-2: 

Summary of PiG Thresholds Chosen.

Table 2-2: Summary of PiG Thresholds Chosen

Modeled Area NOX Threshold (tpd)

Texas 5.0

Adjacent States (LA, AR, OK) & Mexico 7.5

Next ring of States (MS, etc.) 10.0

Next distant ring of States (AL, etc.) 15.0

Other States, Canada & Offshore 25.0

The NOX threshold of 5.0 tpd in Texas denotes that any individual stack or co-located group of 

nearby stacks that totaled 5.0 or more tpd of NOX emissions on an episode day were tracked as a 

PiG source. If multiple stacks were close enough together for their plumes to merge (within 200 

meters of each other), and the aggregate NOX emission rate for the cluster exceeded the 

threshold value, a new source was created with the combined NOX emission rate of the cluster, 

and this source was flagged for PiG treatment. The stack parameters of the new source became 

an average of the stack parameters of all of the sources in the cluster. The TCEQ modeled both

individual PiGs and combined PiGs within each of the modeled areas of Table 2-2. The EPS3 

module, PiGEMS, provides a summary of the PiG treatment. There were a total of 258 PiG 

sources chosen for the entire domain, 200 of which are co-located combined new stacks.

2.1.4. Summary of June 2006 Base Case Point Sources

Snapshots of the point source emission files processed with EPS3 for CAMx in each episode are 

presented in Table 2-3: Base Case AFS Files for the DFW June 2006 Episode and Table 2-4: 

Base Case AFS Files for the DFW AQS1 Aug 15-Sep 15, 2006 Episode . As discussed earlier, the 

AMPD files may be referred to as ARD or CAMD in file name conventions. The version number 

on each dataset indicates a change from the previous version (e.g., “v8”). The regional AFS file 

for the GWEI contains monthly emissions for June only and the regional AFS file for Canadian 

emissions contains annual emissions. The FTP download website for these files (or their 

successors) is ftp://amdaftp.tceq.texas.gov/pub/TX/ei/basecase/point.

Table 2-3: Base Case AFS Files for the DFW June 2006 Episode

Area AFS Point Source Emissions File Hourly Daily Special

Texas afs.osd_2006_with_ards_removed_CB06_RPOlcp_v3 X

Texas afs.ard_TX_29may_thru_02jul2006_RPOlcp X

Texas afs.aggVOC_extra_alkenes_for_2006_lcpRPO.v3 X

Texas afs.landing_losses_3Q06_aver_day_episode_lcpRPO.v1 X

Regional afs.2008NEIv2_noTX_noIPM_noRail_noAirport X

Regional afs.ard_USA_29may_thru_02jul2006_RPOlcp X

Regional afs.gwei.2005.4pol.lcpRPO Monthly

Regional afs.Mexico_from_phaseIII_1999NEI_4pols.RPOlcp X
Area AFS Point Source Emissions File Hourly Daily Special

Regional afs.canada_2006_all_pols.RPOlcp Annual

Table 2-4: Base Case AFS Files for the DFW AQS1 Aug 15-Sep 15, 2006 Episode

Area AFS Point Source Emissions File Hourly Daily Special

Texas afs.osd_2006_with_ards_removed_CB06_RPOlcp_v3 X

Texas afs.ard_TX_15aug_thru_15sep2006_RPOlcp X

Texas afs.aggVOC_extra_alkenes_for_2006_lcpRPO.v3 X

Texas afs.landing_losses_3Q06_aver_day_episode_lcpRPO.v1 X

Regional afs.2008NEIv2_noTX_noIPM_noRail_noAirport X

Regional afs.ard_USA_15aug_thru_15sep2006_RPOlcp X

Regional afs.gwei.2005.4pol.lcpRPO Monthly

Regional afs.Mexico_from_phaseIII_1999NEI_4pols.RPOlcp X

Regional afs.canada_2006_all_pols.RPOlcp Annual

The TCEQ chose the second Wednesday of the June 2006 episode as a representative day for 

reporting base case emissions totals. Table 2-5: 2006 DFW Base Case Episode Day (June 14, 

2006) Emissions Summary summarizes emissions for that day.

Table 2-5: 2006 DFW Base Case Episode Day (June 14, 2006) Emissions Summary

Emissions Source

DFW 

NOX

(tpd)

DFW 

VOC 

(tpd)

TX minus 

DFW

NOX (tpd)

TX minus 

DFW

VOC (tpd)

U.S. minus 

TX NOX

(tpd)

U.S. minus 

TX VOC 

(tpd)

Non-EGUs (OSD) 48.0 49.5 704.5 569.0 4538.8 2457.5

EGUs (ARD) 8.4 1.0 513.7 15.4 7144.3 82.2

Tank Landing Losses 6.5

HRVOC Reconciliation 19.3

2.2 2006 Baseline Point Source Modeling Emissions Development

The 2006 point source emissions used in the base case are specific to individual days and hours, 

for the AMPD EGU portion of the EI. For the baseline case, the TCEQ created files that 

represent a typical ozone season (summer) day in 2006. The subsections that follow discuss how 

the baseline emissions differ from the base case.

2.2.1. Texas Point Sources

2.2.1.1. Ozone Season Daily (OSD)

The OSD point source emissions for the typical 2006 baseline day are the same as the 2006 base 

case OSD emissions, as these are the average OSD emissions extracted from STARS.

Table 2-6: 2006 Baseline OSD Emissions in Texas shows the modeled ozone precursor 2006

baseline totals for point sources in the DFW 10-County nonattainment area (NAA), HGB, and 

the rest of Texas.
Table 2-6: 2006 Baseline OSD Emissions in Texas

Area NOX

#points

NOX

tpd

VOC 

#points

VOC 

tpd

DFW 1,427 41.67 4,421 42.83

HGB 4,628 125.42 24,150 206.37

Rest of TX 8,893 584.49 27,046 369.21

The “#points” entry in Table 2-6 is the total number of point sources in that area. Emissions 

were summed within the area to give the area emissions total. The TCEQ typically eliminates 

zero emissions records, and the EPS3 processor drops VOC records with zero emissions because 

they do not have a speciation cross reference.

2.2.1.2. Hourly AMPD Point Sources

To develop an AMPD EGU baseline, the TCEQ averaged the AMPD NOX for each hour of the day 

for each unit for four months of 2006 to cover the two episodes (June 1 through September 30).

These data records represent the typical ozone season day that maintains the temporal profile of 

the individual units. Corresponding hourly average CO and VOC emissions were calculated from 

STARS OSD, stack-specific emissions by multiplying CO:NOX and VOC:NOX ratios by the hourly 

NOX rate for each AMPD unit.

2.2.1.3. Tank Landing Loss (TLL) Survey

The 2006 baseline for floating roof TLL surveys in HGB was calculated as the average of the 

hourly emissions for each tank point source of the survey for the third quarter modeled episode 

days of 2006. This average was used for both the base case and baseline modeling. Details about 

these sources are available in previous SIP documentation, namely the March 2010 HGB SIP

Appendix B, Section 2.2.1.4.

2.2.1.4. Emissions Inventory Reconciliation in HGB (aka, HRVOC Reconciliation, Extra 

Olefins)

The 2006 HRVOC Reconciliation emissions remain unchanged from the 2006 base case.

2.2.2. Outside Texas

2.2.2.1. States Outside of Texas, Non-EGU NEI

For the states outside of Texas, the TCEQ used the same2008 NEI-based non-EGU file 

generated for the base case. A typical June day was already being used in the base case for the

non-EGUs (NEGU). Table 2-7: 2006 Baseline Emissions Summary for Non-AMPD Points 

Outside of Texas summarizes the non-AMPD emissions for the 2006 baseline.

Table 2-7: 2006 Baseline Emissions Summary for Non-AMPD Points Outside of 

Texas

STATE NOX tpd VOC tpd

Arkansas 94.11 73.98

Louisiana 391.31 183.45

Oklahoma 171.66 66.89

Other States, outside Texas 4346.26 2323.33
2.2.2.2. States Outside of Texas, EGUs

The 2006 baseline for the AMPD sources of the other states is a calculated typical summer day 

with hourly emissions that are the average for each Acid Rain point source for the four months 

of 2006 to cover the two episodes (June 1 through September 30). VOC and CO emissions for 

each hour of the typical summer day come from the hourly NOX emissions and the VOC:NOX

and CO:NOX ratios, computed from the daily emissions data for each AMPD point.

2.2.2.3. Offshore, Mexico, and Canada

The Offshore 2005 GWEI, the 1999 Mexican NEI, and the 1995 Canadian baseline point source 

files are the same as the base case files, since they are already being modeled as an average day.

2.2.3. Summary of 2006 Baseline Point Sources

The point source emission files that were processed with EPS3 for CAMx for the baseline 

(typical summer day) are presented in Table 2-8: AFS Files for the 2006 Baseline. The regional 

AFS file for the GWEI contains monthly emissions for June only and the regional AFS file for 

Canadian emissions contains annual emissions. The version number on each dataset indicates a 

change from the previous version (e.g., “v2”). As discussed earlier, the AMPD files may be 

referred to as ARD or CAMD in file name conventions. The FTP download website for the point 

source files or their successors is ftp://amdaftp.tceq.texas.gov/pub/TX/ei/baseline/point.

Table 2-8: AFS Files for the 2006 Baseline

Area AFS Point Source Emissions File Hourly Daily Special

TEXAS afs.ard_JUN2SEP_2006_CAIR_avg_day_all_pols_RPOlcp X

TEXAS afs.osd_2006_with_ards_removed_CB06_RPOlcp_v3 X

TEXAS afs.landing_losses_3Q06_aver_day_episode_lcpRPO.v1 X

TEXAS afs.aggVOC_extra_alkenes_for_2006_lcpRPO.v3 X

REGIONAL afs.ard_usa_episode_minus_texas_JUN2SEP_2006_RPOlcp X

REGIONAL afs.2008NEIv2_noTX_noIPM_noRail_noAirport X

REGIONAL afs.gwei.2005.4pol.lcpRPO Monthly

REGIONAL afs.Mexico_from_phaseIII_1999NEI_4pols.RPOlcp X

REGIONAL afs.canada_2006_all_pols.RPOlcp Annual

Table 2-9: 2006 Baseline Point Source Emissions Summary summarizes the baseline emissions.

These tabulated emissions are AFS totals input to EPS3. CAMx input values may differ.

Table 2-9: 2006 Baseline Point Source Emissions Summary

Emission Source

DFW 

NOX

(tpd)

DFW 

VOC 

(tpd)

TX minus 

DFW 

NOX (tpd)

TX minus 

DFW 

VOC (tpd)

U.S. minus 

TX NOX

(tpd)

U.S. minus 

TX VOC 

(tpd)

NEGUs (OSD) 48.0 49.5 704.5 562.2 4538.8 2457.5

EGUs (ARD) 9.6 1.0 534.7 21.7 7757.3 88.3
Emission Source

DFW 

NOX

(tpd)

DFW 

VOC 

(tpd)

TX minus 

DFW 

NOX (tpd)

TX minus 

DFW 

VOC (tpd)

U.S. minus 

TX NOX

(tpd)

U.S. minus 

TX VOC 

(tpd)

Tank Landing Losses 6.5

HRVOC 

Reconciliation 19.3

Below in Table 2-10: DFW10-County EGU emissions for the 2006 Baseline, is a summary of the 

10-County Baseline EGU emissions for the 2006 Episodes.

Table 2-10: DFW10-County EGU emissions for the 2006 Baseline

Owner/Sitename County NOX

(tpd)

VOC 

(tpd)

CO 

(tpd)

PM 

(tpd)

SO2

(tpd)

NH3

(tpd)

FPLE Forney Electric Kaufman 3.48 0.01 0.23 0.75 0.07 0.00

Midlothian Energy Ellis 1.23 0.28 1.30 0.74 0.06 0.02

Luminant Lake Ray 

Hubbard Dallas 0.85 0.09 0.36 0.12 0.01 0.00

Garland Power Ray 

Olinger Collin 0.76 0.07 0.68 0.08 0.01 0.00

Wise County Power 

Plant Wise 0.76 0.19 0.20 0.08 0.03 0.08

Extex LaPorte 

Mountain Creek Dallas 0.67 0.11 0.72 0.16 0.01 0.01

Luminant North Lake Dallas 0.56 0.03 0.18 0.03 0.00 0.00

Ennis Power Ellis 0.55 0.00 0.13 0.15 0.01 0.04

Extex LaPorte Handley Tarrant 0.30 0.14 0.52 0.19 0.02 0.02

Brazos Electric 

Johnson County Johnson 0.25 0.07 0.16 0.28 0.00 0.01

Garland Power 

Spencer Denton 0.18 0.03 0.29 0.04 0.00 0.00

Garland Power 

C.E.Newman Dallas 0.03 0.00 0.00 0.00 0.00 0.00

DFW Area Electric 

Utility Total - 9.63 1.03 4.77 2.61 0.22 0.18

2.3 2018 Future Year Point Source Modeling Emissions Development

This section describes the development of the 2018 future year point source EI. The 2008 eighthour ozone attainment date for the DFW nonattainment area, classified as Moderate, is 

December 31, 2018. The modeled attainment year is 2018.

Many factors create the foundation for the future case point source EI prior to control strategies

and/or sensitivity analyses, including a starting point that we refer to as the “projection base”, 

emission credits in the bank for permit expansion offsets and compliance, economic projections, 

EGU expansions, newly-permitted EGUs, shutdown EGUs, EGUs to be retired, existing 
emissions controls, source caps, trading programs, other state measures, and other federal 

measures,

The TCEQ uses the most complete and accurate emissions data available, when given enough 

time and resources to complete a SIP revision. This effort is most important for Texas emissions 

data, since the modeling results may provide a basis for future banking and trading 

considerations, and the basis for many other determinations. For this SIP revision, the TCEQ 

used the most current STARS and AMPD data sets available – 2012 and 2013, respectively, --

from which to develop a future case EI. These “projection base” years also become the baseline 

for emission credit generation.

The 2012/13 projection base emissions are projected into the future to develop 2018 future case 

emissions. All of the ozone precursor emissions are projected. The future case EI provides the 

basis to determine if attainment has been reached and is the starting point for any 2018 control 

strategy testing and/or sensitivity analyses, if required.

In general, baseline emissions are projected, i.e. they are grown to the attainment year and onthe-books controls (those that will be in place after the baseline year and prior to the attainment 

year) are applied. The on-the-books controls are controls for which enforceable emissions 

reductions rules have been written already; they are not additional proposed rules that result 

from this SIP revision. Proposed rules would be modeled in a 2018 control strategy EI or as part 

of Reasonably Available Control Measure (RACM) analyses.

This section of this appendix addresses the above issues.

2.3.1. Regulations and the Cap-and-Trade Programs

In some instances, growth of future emissions is limited by regulation. Prior to discussing

growth and the development of emission files for specific categories and areas of the state, a 

description of the various regulations and trading programs is provided here, since they are

referenced in several sections below.

The Clean Air Interstate Rule (CAIR) limits NOX and SO2 emissions for affected power plants 

throughout Texas, as well as NOX emissions in certain states during ozone season. In the eight 

county HGB region, the Mass Emissions Cap and Trade program (MECT) limits NOX emissions 

for accounts in the program. In Harris County, HRVOC Emissions Cap and Trade (HECT) limits 

HRVOC emissions for certain point sources. Besides MECT, HECT, and CAIR, there are other 

regulations and agreements that affect certain NOX sources in the state, some of which have 

compliance dates between the projection base year(s) and the attainment year, but for most, the

compliance date has already passed and are accurately modeled using the reported projection 

base year(s) emissions. Again, the projection base years are 2013 for AMPD EGUs and 2012 for 

all other Texas point sources, and the attainment year is 2018.

2.3.1.1. Clean Air Interstate Rule Background

The EPA’s CAIR program limits NOX and SO2 emissions for affected power plants in 27 eastern 

states and the District of Columbia. The definition of an EGU for the CAIR program is 

approximately the same definition as that for a Federal Clean Air Act Title IV Acid Rain unit, i.e., 

larger than 25 MW and more than one-third of its generation going to the public grid for sale.

CAIR is a cap-and-trade program, with each of the CAIR-applicable states given calculated NOX

and SO2 budgets by the EPA. EPA’s modeling determined that Texas significantly contributed to 

the nonattainment of the particulate matter of 2.5 microns and less (PM2.5) standard of two 

counties in Illinois. Texas was not included for eight-hour ozone contribution. Thus, Texas is not 
part of the CAIR ozone season (May through September) NOX budget, only the annual NOX

budget program. More details on CAIR are available on EPA’s “CAIR for Texas” webpage, 

http://www.epa.gov/cair/tx.html.

CAIR is implemented in two phases. For NOX, Phase I covers the years 2009-2014 and Phase II 

covers the years 2015 and later; for SO2, Phase I covers the years 2010-2014 and Phase II covers

the years 2015 and later. Because 2018 is the DFW ozone attainment year, this DFW SIP 

revision incorporates the stricter CAIR Phase II, which provides for a Texas state-wide NOX

budget of 150,845 tpy or 413 tpd. The CAIR allocations and past transactions for all relevant 

states can be found at EPA’s Air Market Programs data query or prepackaged data website, 

http://ampd.epa.gov/ampd/.

CAIR provides a NOX emissions cap for most AMPD EGUs in Texas (and other CAIR states).

CAIR sources (i.e., pieces of equipment) at applicable sites are allocated a specific amount of 

allowances for each compliance year referred to as allocations. The sum of each state’s

allocations of all CAIR sources equals the EPA-prescribed state’s budget. At the end of each year,

each site with CAIR sources must have sufficient allowances to cover the total emissions from all 

its CAIR sources. Subject sources can purchase or sell allocated allowances; their emissions in 

any year are not limited to their allocation for that year. The “reconciliation” of available 

allowances and annual emissions is done by EPA following the completion of the compliance 

year. Any allowances not needed for a compliance year can be banked and are available for the 

site to use in future years. It should be noted that though the state budget is distributed to each 

subject source, compliance is a done at the site level. As CAIR is a cap-and-trade program, 

modeling each CAIR source solely at its assigned allocation would be inaccurate, because many 

sources in Texas consistently operate above their CAIR allocation, while others are consistently 

below. In addition, some points in CAIR are in the HGB MECT program as well, which 

complicates the modeling of these sources. TCEQ accounts for the cap-and-trade aspects of 

CAIR and the overlap of CAIR and MECT sources, as described below in Section 2.3.1.4, 

Modeling the Cap-and-Trade Programs.

2.3.1.2. Mass Emission Cap and Trade (MECT) Background

The MECT program provides NOX emission limits for applicable sources as specified in 30 TAC 

§101.351. The MECT program covers almost all pieces of NOX-emitting equipment in HGB. Sites 

with these point sources comply with the source category emissions limits via the cap-and-trade 

method. The TCEQ allocates allowances to each point source (i.e., piece of equipment) at a site 

(account, RN). Similar to the CAIR program, the MECT program also allows trading and 

banking of allowances. A key difference between the CAIR and MECT programs is that in the 

MECT program unused allowances can be banked only for one additional compliance year,

while in CAIR, unused allowances can be banked indefinitely. To comply with the MECT 

program, each site in the MECT program should have sufficient allowances to cover the total 

annual emissions from all its MECT sources. The TCEQ’s Emissions Banking and Trading (EBT) 

Team QCs the annual reports, submitted by subject sites, to verify that the site has allowances 

equivalent to the total NOX emissions from the MECT points at the site. Similar to the CAIR 

program, in the MECT program though, the MECT cap is distributed to each subject source (in 

the form of annual allocations), and compliance is a done at the site level. More detail about the 

MECT program can be found in in the March 2010 HGB SIP Appendix B.

The MECT cap, as of December 31, 2013, was 40,176 tpy or 110 tpd. In previous SIPs, MECT 

sites were modeled at their future year allocations, regardless of their trading history. The fact 

that some MECT sites sell all or a portion of their allowances each year permanently via “stream 
trades” or each year, gave TCEQ the impetus to model a more spatially-realistic future case

distribution of MECT Source emissions, as described below in Section 2.3.1.4.

2.3.1.3. HRVOC Emissions Cap and Trade (HECT) Background

The HRVOCs are ethylene, propylene, butadiene, and the butenes. The HECT program limits 

HRVOC emissions discharged from applicable point sources in Harris County as specified in 30 

TAC §101.391. The HECT program is a cap-and- trade program similar to the MECT program 

with compliance being handled by TCEQ’s EBT team. The HECT cap applies to HRVOC.

Commonly included sources are flares, non-tank stacks, and cooling tower emissions. However, 

unlike the MECT program, the HECT cap is distributed by site (RN, account) via annual 

allocations. The HECT cap, as of December 9, 2013, was 2590.3 tpy or 7.1 tpd. See footnote 7 in 

Section 2.1.1.4.1 above for additional background, speciation procedures, and development of 

the HRVOCs and HECT program.

HECT allowances were allocated to applicable sites in proportion to the site's level of activity, 

determined from each site's selection of a twelve-consecutive-month baseline from 2000 

through 2004. HECT sites were given the greater of 5.0 tons of HECT allowances or the 

allocation from the site, determined from using the equation listed in 30 TAC §101.394(a)(1). 

Additional details of this Harris County control program are described in previous SIP 

documentation.

2.3.1.4. Modeling the Cap-and-Trade Programs

The TCEQ administers four cap and trade programs in Texas: (1) the Emissions Banking and 

Trading of Allowances program (also known as the SB7 program) for SO2 and NOX emissions, 

(2) the MECT program for NOX emissions, (3) the HECT program for HRVOC emissions, and

(4) the CAIR program for SO2 and NOX emissions. The TCEQ models these cap and trade 

programs by limiting the future emissions of sources subject to these cap and trade programs to 

the appropriate program’s total future year cap. If multiple programs cover a set of sources, the 

most stringent (smallest total cap) program is modeled. Three cap and trade programs were 

used to limit future year emissions for select sources in Texas: MECT, HECT, and CAIR. The 

SB7 program, which affects EGUs, is not modeled as it is less stringent than CAIR Phase. The 

three cap and trade programs used to model future year NOX and HRVOC emissions are 

summarized in Table 2-11: Texas Cap-and-Trade Program Summary. SO2 is not a modeled 

precursor for ozone.

Table 2-11: Texas Cap-and-Trade Program Summary

Program Pollutant 

Affected Geographical Scope 2018 Program Cap for Texas Sources(tpy)

CAIR NOX

27 eastern states and the 

District of Columbia 150,845

MECT NOX HGB Nonattainment Area 40,176.2

HECT HRVOC Harris County 2,588.6

The spatial representation of future year emissions of the sources subject to these cap-and-trade 

programs has typically been based on the source’s future year allocation of allowances specified 

for the relevant cap and trade program(s). Since future year allocations are typically distributed 

many years in advance13, the sources that received future year allowances in many cases may not 

 13 Details regarding future year allocations for CAIR, MECT, and HECT can be found in 30 TAC §101.506, 

§101.353, and§101.394, respectively.
be operational in the future year. While the total future emissions from all the sources subject to 

each of the programs is limited to the 2018 program cap listed in Table 2-11, the TCEQ spatially 

distributed the 2018 cap to sources that are expected to be operational in the future using 

historical trend analysis for each program, as detailed below. The distributed annual 2018 site 

emissions (tons/year) were then converted to future year ozone season day emissions 

(tons/day). The distribution of the 2018 program cap described here is only intended to spatially 

represent future year emissions for modeling purposes and does not take the place of official 

allocation of allowances associated with these programs. The official future year allocations can 

be found at the EBT program web page 

(http://www.tceq.texas.gov/airquality/banking/banking.html).

The general procedure for the historical trend analysis used to spatially distribute the future 

year program caps consisted of the following steps14.

1. For each site, the difference between the total reported site emissions and the site’s 

annual allocation for all past compliance periods for a program was calculated. The 

difference was termed “site cap gap”.

2. A positive site cap gap for a compliance year indicated that the site had leftover 

allowances that it could potentially sell to other sites in the program (a spatial trade) or 

bank for future use (a temporal trade). A site with a positive cap gap is a potential 

“Seller” (spatial or temporal). Similarly, a site with a negative site cap gap indicated that 

the site purchased allowances (spatially or temporally) for compliance purposes and was 

termed “Buyer”. The terms “Seller” and “Buyer” are used to refer to the potential to trade 

and not actual trades. In each compliance year, a site is a “Seller” or a “Buyer” in each 

program based on the site cap gap for that program, i.e., in 2009 a site could be a “Seller” 

in the CAIR program but a “Buyer” in the MECT program.

3. If a site was a “Seller” (had a positive cap gap) 80%15 of the time then site was termed to 

have a “Seller” trend. Similarly, if a site was a “Buyer” (negative cap gap) 80% of the time 

then the site was termed to have a “Buyer” trend. The 80% cut off for a trend translates 

into a site being a “Buyer” or a “Seller” for a certain number of years depending on the 

total number of completed compliance years for each program (4 out of 5 years for the 

CAIR program, 5 out of 6 times for the HECT program and 8 out of 10 times for the 

MECT program).

4. If a site exhibited a trend and the site’s behavior for the latest projection-base year 

followed the trend, then the annual emissions for the projection-base year was assigned

as future year emissions to the site. This is because if a site exhibited a trend then it can 

be reasonable expected to have a similar behavior in the future year, i.e., a site with a 

“Seller” trend can be expected to have a positive site cap gap in the future year and a site 

with a “Buyer” trend can be expected to have a negative cap gap in the future year. Since 

the annual emissions from the projection-base year were representative of the trend 

behavior, the future year site emissions were represented by the projection-base year 

emissions. The projection-base year used for HECT sources is 2012 and the projectionbase year used for CAIR is 2013. For MECT, the 2012 projection-base year was used for 

all sources including those that were also in CAIR, since this was the latest year for which 

MECT compliance related information was available from the EBT database.

 14 Data regarding annual emissions and allocations was obtained from the TCEQ’s EBT database for 

MECT and HECT programs and from EPA’s AMPD web query tool for CAIR. 15 The 80% cut-off was chosen qualitatively based on the number of completed compliance years for the 

three programs (at the time of SIP development). CAIR had the smallest number of years completed 

compliance years (5 years compared to 6 years for HECT and 10 years for MECT), a trend of 4/5 years 

equals 80%. 
5. Sites below the 80% threshold were termed as “Neither.” Sites that did not have an 

identifiable trend or sites that had a trend but the behavior in the projection-base year 

did not follow the identified trend, then the future year site emissions were represented 

using future allocations of allowances.

6. To be conservative and to account for possible yearly variations, the assigned caps were 

proportionally scaled up such that total annual modeled emissions for sources subject to 

these programs equal the program’s respective 2018 available caps. The available 

program caps for MECT and HECT are those listed in Table 2-11. For CAIR, the available 

program cap was reduced from the 150,845 tons to accommodate newly permitted (but 

not yet constructed) EGUs.

The historical trend analysis was performed individually for each of the three programs. For 

sources subject to both CAIR and MECT, the 2018 annual site emissions determined using the 

historical trend analysis for the MECT program was used as it is the more stringent program. 

Detailed tables with the results of the historical trend analysis for each program are available at 

the TCEQ FTP modeling website at

(ftp://amdaftp.tceq.texas.gov/pub/TX/ei/fy2018/point/cap_trade/).

2.3.1.5. Ellis County (Midlothian) Cement Kilns

Site-wide (by account) NOX caps were modeled based on this Chapter 117 rule that applies to 

each of the kilns in Ellis County (in the DFW nonattainment area, city of Midlothian). The rule 

applies ozone season (March 1 through October 31) caps, totaling 17.6 tpd to the ten kilns at the 

three sites. Slight modification to the modeled distribution of this cap among a few of the kilns

has been made in this SIP revision, based on consent decrees and permit modifications. The 

details regarding the current implementation of this cap are described in Section 2.3.3 below.

2.3.2. Attainment Areas of Texas

The attainment areas of Texas include all of Texas except DFW and HGB. The subsections below 

address growth and control implementation separately. Subsection 2.3.2.1.2, Newly-Permitted 

EGUs, below, includes new units in attainment and non-attainment areas.

2.3.2.1. Attainment Area 2018 Growth Projections

Different growth projection techniques were applied to the EGUs that have AMPD hourly data 

versus the non-EGUs (NEGU). The techniques used are similar to EPA projection methods for 

modeling future cases, except that the TCEQ does not use the Integrated Planning Model (IPM).

2.3.2.1.1. EGUs

To develop the AMPD EGU 2013 projection-base, the TCEQ averaged the AMPD NOX for each 

hour of the day for each unit for the June through September time period, similar to the 

procedure that generated the 2006 baseline EGUs. The TCEQ chose the more recent dataset 

from which to project because it is newer and contains more of the actual emissions growth from 

newer units. Not all EGUs have hourly AMPD data and not all NOX point sources at EGU 

facilities are AMPD point sources. The non-AMPD EGUs were projected from their 2012

emissions along with the NEGU point sources, as discussed below in Subsection 2.3.2.1.3, NonEGUs (NEGU).

The TCEQ generates hourly emissions records for the non-AMPD pollutants (NH3, CO, PM2.5, 

and VOC) for AMPD point sources using 2013 heat input data. From STARS, the TCEQ obtains 

annual emissions for each pollutant and computes a pollutant-to-heat input ratio from the 

annual totals. Computationally, the heat input and emission totals need to be from the same 

year, but a given year’s set of ratios can be used for another year if, for example, one of the 
datasets (STARS, for example) is not available. With a valid set of pollutant-to-heat ratios, the 

TCEQ computed hourly emissions for each pollutant based on the AMP hourly heat input.

The complete set of 2018 Texas EGUs, for future case modeling, consists of the 2013 AMPD 

EGUs, the post-2013 new EGUs (a.k.a., newly-permitted EGUs) discussed in the following 

section, and the projected 2012 non-AMPD EGUs. As with previous SIP revisions, the TCEQ 

assumes that the EGU growth in the state comes from newly-permitted EGUs.

2.3.2.1.2. Newly-Permitted EGUs

It is always better to provide known growth/expansions at the physical locations where they are 

projected to occur, rather than growing existing emissions in place. Growth in EGUs in Texas is 

accomplished with the addition of newly-permitted EGUs since the projection-base year, all 

within the constraints described in the controls subsection below, in addition to TCEQ New 

Source Review permitting requirements. This subsection describes the procedures for 

developing the newly-permitted EGU EI. It includes the new units in attainment and nonattainment areas.

Texas EGU emissions for 2018 were developed by researching and compiling data from various 

sources. These sources include:

• Electric Reliability Council of Texas (ERCOT): http://www.ercot.com/;

• TCEQ air permitting projects with combustion turbines;

http://www.tceq.state.tx.us/assets/public/permitting/air/memos/turbine_lst.pdf; and

• TCEQ New Source Review Permits Information Management System (NSRP IMS) internal 

document server.

Information from these sources includes individual units’ disposition (i.e., operating status), 

new units coming online, units to be mothballed, and units to be shut down or retired. The 

criteria the TCEQ uses for adding new units are: (1) the units are expected to be operational by 

the end of 2018, (2) the owners applied for, and were granted, a TCEQ air permit, and (3) the

owners obtained an Interconnection Agreement (IA) from ERCOT (for those units planned 

within the ERCOT grid). All three of these conditions must be met in order for the unit(s) to be 

included in the future case modeling. The TCEQ assumed that by the 2018 ozone season, all 

current (as of October 2013) mothballed and reliability-must-run (RMR) units would be retired.

All data sources were reconciled to ensure all units were accounted for, and that their status as 

of May 2014 was modeled. As the most recent EGU emissions data for modeling is from 2013

AMPD, new EGUs are based on additions and changes subsequent to 2013.

ERCOT covers approximately 85% of the power grid in the state. For the five years between 

December 2013 and December 2018, a comparative analysis was performed to verify that all 

new units planned by ERCOT are accounted for, and there is ample generation proposed from 

the newly permitted units to meet the projected demand in electricity. ERCOT projects

approximately 3800 megawatts of new non-wind resources with a reserve margin of 

approximately 12.5%. The modeled new units meet this projection.

For the newly-permitted EGUs, emissions were calculated based on the permit Maximum 

Allowable Emission Rates Table (MAERT), which is always greater than the actual operating 

emissions. Pollutants acquired from the permits were NOX, VOC, and CO. The method of 

determining the allowable emissions differs based on the type of unit and its primary purpose 

for being constructed. For example, coal plants may have a 30-day rolling average emission rate, 

while gas turbines may have a short term allowable emission rate in pounds per hour (pph)
and/or a long term allowable emission rate in tpy. In some cases, a unit may have a combination 

of the above, in addition to maintenance, startup and shutdown (MSS) emission limits.

When available, the 30-day pph emissions limitation was used. These have most often been 

available for solid fuel-fired units. This time frame represents a good compromise between the 

standard short-term allowable, which sometimes includes MSS, and the standard long-term 

permit allowable. The short term allowable in pph, when converted to tpd, is often substantially 

more than a unit would realistically emit in any day; the long-term allowable in tpy, when 

converted to tpd, may under-represent what a unit could emit during any one day, especially 

during a summer day during the ozone season.

MSS permitting has become more routine in the last several years. These activities help provide

a more realistic operating scenario than the maximum of the short-term or long-term emission 

rates. This is especially important for those units that have many MSS events during a typical 

summer, such as the peaking units, which operate only during the peak demand times. MSS 

limits vary between permits, depending on specific representation in permit applications.

Examples of permitted MSS and how they are modeled are described in previous SIP 

documentation.

The emission rates calculated represent worst case for some units, but for most, they represent a 

typical summer day during the ozone season, corresponding to some of the highest days of 

electricity demand. Some facilities on the “new” list may have operating data in the 2013 base 

year but, if the AMPD reported emissions are not reasonable for a complete year of operation, 

these facilities are modeled at their permitted values. The complete list of newly-permitted 

EGUs added as the EGU growth in the state sorted by area is provided as Table 2-12: Newly 

Permitted EGUs (post 2013) in Texas as of May 2014.

Table 2-12: Newly Permitted EGUs (post 2013) in Texas as of May 2014

Area Sitename County Permit NOX

(tpd)

Operating 

in 2013

ELP Montana Power Station El Paso 0.105

ELP Montana Power Station El Paso 0.105

ELP Montana Power Station El Paso 0.105

ELP Montana Power Station El Paso 0.105

ETX Panda Temple Power Bell 0.454

ETX Panda Temple Power Bell 0.454

ETX Panda Temple Power Bell 0.454

ETX Panda Temple Power Bell 0.454

ETX Panda Sherman Grayson 0.675

ETX Panda Sherman Grayson 0.675

ETX Woodville Renewable Power Project Tyler 0.890

HGB W. A. Parish Fort Bend 0.310 Y

HGB Deer Park Energy Center Harris 1.226

HGB Channel Energy Center Harris 0.880
Area Sitename County Permit NOX

(tpd)

Operating 

in 2013

SAN Guadalupe Generating Station Guadalupe 1.017

SAN Guadalupe Generating Station Guadalupe 1.017

WTX Jones Peaking Facility Lubbock 1.380 Y

WTX Mustang 6 Yoakum 0.822 Y

WTX TC Ferguson Power Plant Llano 0.365

WTX TC Ferguson Power Plant Llano 0.365

WTX FGE Texas Mitchell 0.309

WTX FGE Texas Mitchell 0.309

Table 2-12 includes (1) the calculated NOX emissions from permit applications and MAERTs, 

representing realistic average day emissions, and (2) the NOX emission rates after incorporating 

the existing rules that may apply to AMPD EGUs. The TCEQ assumed NOX controls, offsets, or 

credit purchases will be used to meet these NOX emissions rates. VOC and CO rates are modeled 

at their permitted levels. There were sufficient CAIR and MECT allowances available for all new 

EGUs to be modeled at their permitted rate.

The temporal distributions of the newly-permitted EGU emissions are based on those of existing 

units of similar equipment type or SCCs. For each SCC included in the newly-permitted EGU 

list, an average temporal distribution was calculated, based on diurnal profiles of existing units

with the same SCC within the state. For some units on the new EGU list, a corresponding SCC 

did not exist for existing units. In these cases, the default flat profile was assigned. An example 

of the profile used for a natural gas turbine is discussed in previous SIP documentation.

2.3.2.1.3. Non-EGUs (NEGU)

When the AMPD units are removed from the point source EI for hourly treatment, the 

remainder is OSD. The TCEQ refers to these remaining units as NEGUs. The basis for future 

growth (projection base year) for NEGUs in the Texas attainment areas was the most current 

complete and quality control checked year of STARS emissions: 2012 OSD emissions, already an 

average OSD from STARS.

The TCEQ estimated projection base (2012) to future case (2018) growth projections using 

growth factors developed via contract to TCEQ by ERG. The ERG growth factors webpage at 

(ftp://amdaftp.tceq.texas.gov/pub/TX/ei/fy2018/point/AFS/ERG_growth_factors/) are based 

on county (FIPS) and North American Industry Classification System (NAICS). To manage the 

growth factors, TCEQ developed a table that assigned growth factors for all 2012 STARS 

emission paths. The ERG data provided growth factors for most of the STARS paths (uniquely 

identified by FIPS, plant, stack and point). In situations where there was not a FIPS/NAICS 

match, the pathway was assigned a growth factor equal to the NAICS average for the state. If 

there was no NAICS match, the next default was the county (FIPS) average growth, and then the 

State average. All pollutants for a path were assigned the same growth factor.

Projection factors were assigned individually to each NEGU path that does not have a recent 

rule applied to it. No factor was applied to a path that must comply with a recent rule, since the 

rule provides an emission limit on that path. A summary of the EGU and NEGU growth in the 

Texas attainment areas is provided as Table 2-13: Summary of Texas Attainment Area Growth 
Projections to 2018. In Table 2-13, a Growth Method of 1 indicates ERG growth factors were

applied to points that do not have recent existing rule limitations; and a Growth Method of 2

indicates the addition of post-2012 point sources and CAIR applied to all points.

Table 2-13: Summary of Texas Attainment Area Growth Projections to 2018

EI

Future 

Case 

Baseline 

Data

Future 

Case 

Baselin

e # 

points

Future 

Case 

Baseline 

NOX (tpd)

Growth 

Method

2012 

Future 

Case 

#points

2012 

Projecte

d NOX

(tpd)

Baseline 

to 2012 

Growth

NEGUs 2012 

STARS 9469 389 1 9469 413 6%

EGUs

2013

STARS/

AMPD

257 387 2 268 430 11%

2.3.2.2. Texas Attainment Areas 2018 Control Implementation

For this SIP revision, all of the existing TCEQ on-the-books controls are accounted for in the 

2012 projection base. To develop the future case, emissions from EGUs in the state are 

controlled via EPA’s CAIR program. For the NEGUs in attainment areas of the state, several 

existing controls were modeled, as described in following subsections.

2.3.2.2.1. EGUs

The TCEQ modeled the CAIR source emissions, using the trend analysis described above in 

Section 2.3.1.4, after accounting for the ozone season peak in AMPD EGU NOX emissions. The 

CAIR caps are annual limits, and CAIR participants will collectively use more of their CAIR NOX

emission credits during the summer ozone season months when electric demand is higher. To 

capture this seasonal variation, the TCEQ scaled historical emissions for each point to match the 

cap, thereby applying the cap over the total time span while preserving emission variations 

within the span.

As noted above, in Section 2.3.2.1.2, the newly-permitted units can be modeled at their 

permitted values using the CAIR cap remaining after distributing the cap to existing EGUs. A 

summary of the distribution of the general and new CAIR pools to areas of Texas is provided as 

Table 2-14: Distribution of NOX CAIR Allowances in Texas.
Table 2-14: Distribution of NOX CAIR Allowances in Texas16

Area Emissions 

Basis

Modeled Allowance 

for 2013 Units, tpd 

Modeled Allowance for 

Post-2013 Units, tpd 

DFW CAIR AMPD 16.76

MECT MECT OSD 0.61

HGB MECT AMPD 36.09

Attainment CAIR OSD 10.06

Attainment CAIR ARD 420.01

The EGU portions of the HGB MECT program also count against the CAIR budget. Overall, 

MECT is more restrictive than CAIR, i.e., lower controlled allowable emission rate, ignoring 

trading, so the difference between CAIR and MECT was distributed to CAIR EGUs not subject to 

the MECT program.

2.3.2.2.2. NEGUs

One existing program expected to further reduce emissions between the future base and 2018 in 

the attainment areas of the state is the Refinery Initiative. The reductions are in attainment 

counties as well as nonattainment counties throughout the state. Unfortunately, the emissions 

reductions are not easily quantifiable (see the description below).

2.3.2.2.2.1. Refinery Initiative

Since the late 1990s, petroleum refineries have been the focus of an EPA enforcement initiative. 

This initiative alleges that, in general, petroleum refineries violated and/or continue to violate 

one or more of the regulatory Clean Air Act provisions. In the interest of settling these 

allegations, without admitting to the alleged violations, many petroleum refiners entered into 

consent decrees with EPA. Since March 2000, the EPA has entered into settlements with 32

petroleum refiners that, collectively, represent 90 percent of U.S. petroleum refining capacity.

According to EPA, these settlements, covering 109 refineries in 32 states, including Texas, will 

result in a reduction of approximately 93,000 tpy of NOX and 256,000 tpy of SO2 upon full 

implementation. See EPA’s Petroleum Refinery Initiative webpage at 

http://www2.epa.gov/enforcement/petroleum-refinery-national-case-results for more details.

The TCEQ has not modeled any reductions for these consent decrees, because most of the 

agreements do not require NOX reductions, and most of them lack enforceable requirements of 

quantified reductions. The TCEQ can verify that several refineries (some in HGB and BPA) have 

modified permits to comply with their consent decrees, but permit reductions do not always 

result in actual reported emission reductions.

2.3.3. Nonattainment Areas (NAA) of Texas

This section describes the specific growth and control implementation applied to the two ozone 

NAAs, DFW and HGB. The NAAs were modeled similarly, although HGB is more complex due 

to the number of TCEQ programs that apply to it. The growth projections to 2018 and any 

existing controls that will affect the areas between the projection base year(s) and 2018 are 

described in subsections below. Since emissions growth in NAAs is strictly limited by 

 16 The tpd includes seasonal adjustments of CAIR and MECT caps based on AMPD data.
nonattainment New Source Review (NSR) rules, the subsections below address growth and

control implementation together.

2.3.3.1. 2018 NAA Growth Projections and Control Implementation

Growth projections were applied to the 2012 and 2013 projection base EIs to obtain the 2018 

future case EI. Different techniques were applied to the EGUs (2013 projection base year) and 

the NEGUs (2012 projection base year).

2.3.3.1.1. NAA EGUs Projections and Control Implementation

As with the attainment areas of the state, the projection into the future begins with a projection

base EI for NAA EGUs that is the typical (average) summer day calculated from AMPD hourly 

emissions for all days in the June through September 2013 time period. Not all EGUs are AMPD

units. The projection base for non-AMPD EGUs is their 2012 OSD emissions, as if they were 

NEGUs.

The complete set of 2018 Texas EGUs, for future case modeling, consists of the 2013 AMPD 

EGUs, the post-2013 newly-permitted EGUs, and the projected 2012 non-AMPD EGUs. As with 

previous SIP revisions, the TCEQ assumes that the EGU growth in the state comes from newlypermitted EGUs. Similarly, the Integrated Planning Model (IPM) that EPA used for its future 

case EGU projections would add new units when it calculates that new capacity (to meet 

demand) is needed. The growth of EGUs in Texas is spatially allocated based on permit 

applications.

2.3.3.1.1.1. Existing EGUs in NAAs

All AMPD EGUs in DFW must comply with the control program, CAIR, and those in HGB must 

comply with CAIR and the more stringent MECT. Just as with the attainment areas, as 

described above in Section 2.3.2.2.1 , an ozone season scaling factor is calculated and applied to 

CAIR because CAIR is an annual cap, yet we are modeling the higher electrical demand ozone 

season.

Similarly, MECT is an annual cap, and account holders do not use these NOX allowances

uniformly across the year – they use more during the peak electrical demand ozone season. To 

compensate for this seasonal variation, the TCEQ computes a set of scaling factors by 

numerically dividing the annual MECT cap for each account by the sum of its emissions over the 

entire year. This factor is a multiplier that, when applied to the projection base (2013) average 

summer emissions, yields a future case set of emissions that are at their MECT cap for the ozone 

season.

2.3.3.1.1.2. Newly-Permitted EGUs in NAAs

Table 2-12, in Section 2.3.2.1.2 above, lists all of the newly-permitted EGUs in each area of the 

state. Again, these new units represent all of the EGU growth in all areas of Texas. There are no 

new planned units in DFW and three newly-permitted units in HGB. These new units were 

assumed to fit into the Texas CAIR cap, except in HGB, where the new units must also fit into 

the MECT cap limit. There was enough CAIR and MECT allowances available [due to 

shutdowns, units that drop from the program, and Discrete Emission Reduction Credits 

(DERCs) that can be used for MECT allowances] to easily model the new units at their permitted 

allowables.

2.3.3.1.2. NAA NEGU Projections and Control Implementation

As with the attainment areas of the state, the projection into the future begins with a projection

base EI for Texas NAA NEGUs -- the 2012 OSD emissions. No individual new NEGU permits 
were modeled as growth, as such a process would be extremely resource intensive for all NEGU 

permit actions in the state. Emissions from NEGUs in the NAAs of the state were projected to 

2018 using the lesser of the ERG growth factors or the emission credits in the bank, described in 

the following paragraphs, except for HGB NOX, which is additionally subject to the MECT 

program. The ERG growth factors are discussed in Section 2.3.2.1.3 Non EGUs (NEGUs).

NAAs cannot grow in major sources of emissions of ozone precursors, NOX and VOC, except by 

purchasing from the bank to obtain emissions offsets during New Source Review of permit 

applications or by sitewide contemporaneous period reductions. The TCEQ assumes that the 

emissions in the TCEQ EBT Registry, i.e., bank, are available to come back into the airshed in 

the future, but are limited by the projected growth of point sources within the NAA. In other 

words, sources will only purchase from the bank what they actually need, and that need is 

projected by TCEQ with the ERG growth factors. Conversely, sources in need of large emissions 

growth in the future (predicted by ERG), can only purchase as much credit as exists in the bank.

For 2018 future case NOX emissions, there were sufficient bank credits to allow growth with the 

ERG factors. 2018 future case VOC growth, however, was limited by the available bank credits.

The procedure for potentially incorporating the banked emissions in the future case begins with 

extracting the banked emissions from the TCEQ’s EBT Emission Reduction Credit (ERC) and 

DERC Registries, which can be found on EBT’s Registry webpage at

http://www2.tceq.texas.gov/airperm/index.cfm?fuseaction=registry.registry.

ERC and DERC totals for each of the NAAs, as of June 19, 2013 were extracted, tabulated, and 

summarized. Table 2-15: Banked Emissions as of June 2013 summarizes these results.

Modelable emissions in Table 2-15 refers to the maximum amount of emissions that could be 

added as growth to the area from banked emissions, with the exception of HGB as noted below.

Table 2-15: Banked Emissions as of June 2013

NAA

NOX

ERCs

(tpy)

VOC

ERCs

(tpy)

NOX

DERCs 

(tons)

VOC 

DERCs 

(tons)

CO 

DERCs

(tons)

Total 

Model

-able 

NOX

Bank 

(tpd)

Total 

Model

-able 

VOC 

Bank 

(tpd)

Total 

Model

-able 

CO 

Bank 

(tpd)

HGB Registry 47.3 788.5 39018.9 1837.4 0.0 6.2 0.0

HGB Modeled Bank 

(Growth) 36.4 606.5 25894.6 1653.7 60.8 6.2 0.0

HGB Model Bank used 

for MECT Compliance 1247.1 3.4

DFW Registry 363.0 153.2 6343.7 4.0 0.0

DFW Modeled Bank 315.7 133.2 5703.3 3.6 0.0 17.0 0.6 0.0

Chapter 101 of 30 TAC requires that an ERC must be surplus to any federal, state or local rule.

Also, the Chapter 101 MECT program DERC-use restrictions for HGB were incorporated in the 

NOX total. 30 TAC Chapter 101.379, DFW DERC Flow Control Rule for 2018, did not offer a 

limitation on the growth for this SIP revision, because the ERG growth projected for DFW was 

less than the DFW banked emissions.
As a worst case, the Modelable bank totals indicated in Table 2-15 incorporate the designated 

eight-hour ozone offset ratios used for the TCEQ NSR program for each of the NAAs as of June 

19, 2013, where an offset ratio of 1.15:1 for moderate areas indicates that the purchaser of ERCs 

must buy 11.5 ton per year of credits for each 10 tpy of increase proposed. Additionally, the 

modelable bank took into account the requirement of Chapter 101 to retire 10 percent of the 

DERCs, as an environmental contribution, upon DERC usage.

Table 2-16: Texas NEGU “No-Rules” Growth Summary shows the growth projected in each of 

the NAAs. Again, the growth was only applied to the sources that were not already limited by 

existing TCEQ rules. 

Table 2-16: Texas NEGU “No-Rules” Growth Summary

Area Projection Index

2012 

STARS 

NOX, 

tpd

2018 

NOX, 

tpd

2012 

STARS 

VOC, 

tpd

2018 

VOC, 

tpd

DFW ERG with bank limit 23.72 23.17 46.69 49.29

HGB ERG with bank limit 17.63 20.73 109.27 115.48

Attainment from ERG factors 409.00 412.94 285.90 316.96

The DFW banked emissions and growth from the ERG factors were compared on a path-by-path 

basis, automated with SAS programming. The bank growth in each NAA was the bank divided 

by the total emissions in the NAA. A path’s share of the bank was based on its fractional 

emissions of the total, and was added to that path. Only the paths not already limited by rules

were allowed to grow via the bank or the ERG factors.

2.3.3.1.2.1. HGB MECT NEGU NOX Control Implementation

The HGB MECT program also limits the amount of NOX from all applicable NEGU sources with 

a cap. The application of this program and its limits are discussed in Sections 2.3.1.2 and 2.3.1.4

above.

2.3.3.1.2.2. HGB HECT NEGU HRVOC Control Implementation

The other cap-and-trade program within HGB that applies to NEGUs is the HECT program. No 

EGUs are in the HECT program. This rule only applies in Harris County. The application of this 

program and its limits are discussed in Sections 2.3.1.3 and 2.3.1.4 above. The HRVOC modeling 

procedure adopted by the TCEQ does not affect the mass flow rates of other non-HRVOC 

compounds in HECT qualifying point sources.

2.3.3.1.2.3. DFW Ellis County (Midlothian) Cement Kiln Cap Control Implementation

As previously discussed in Section 2.3.1.5, the DFW Cement Kilns Source Cap remains 17.6 tpd.

In the past, these have been modeled as shown in Table 2-17: Ellis County Cement Kiln NOX

Caps, below. The table below also shows the projected 2012 NOX emissions from the December 

2011 DFW SIP Revision17 and the 2012 STARS Annual emissions. Thus, by modeling the 

Cement Kiln Cap we are modeling approximately twice the emissions the kilns actually emitted.

Doubling of kiln emissions by 2018 is very unlikely; therefore, the modeled future case for these 

sources is a conservative projection.

 17 December 7, 2011 DFW Attainment Demonstration for the 1997 Eight-Hour Ozone Standard at 

http://www.tceq.texas.gov/airquality/sip/dfw_revisions.html
TXI received a permit modification June 30, 2011 to cease operation of its four wet kilns (future 

emissions of 0.00 tpd) in exchange for increasing clinker production in its newer dry kiln 

process.

On August 14, 2013, Ash Grove entered into a Consent Decree with EPA that would require Kiln 

1 and Kiln 2 to be shutdown/retired by September 2014 and Kiln 3 reconstructed as a dry kiln.

Emissions limits were specified for Kiln 3’s NOX, SO2 and PM emissions in this agreement, but 

this does not change the enforceable NOX Source Cap for the entire site of 4.4 tpd.

Table 2-17: Ellis County Cement Kiln NOX Caps

Sitename FIN EPN

Projected 

2012 NOX

Emissions 

from 

December 

2011 DFW 

SIP 

(tpd)

2012 

STARS 

Annual 

Emissions

(tpd)

2018 

Updated 

Allocation

NOX

Emissions

(tpd)

Ash Grove 2-1 2 1.43 1.13 -

Ash Grove 2-2 6 1.51 1.39 -

Ash Grove 2-3 12 1.45 1.38 4.4

Holcim 62* 62* 2.10 0.00 2.61

Holcim 07* 07* 3.20 1.64 2.69

TXI Operations E-2-2 E2-2 0.00 - -

TXI Operations E-2-4 E2-4 0.00 - -

TXI Operations E-2-6 E2-6 0.00 - -

TXI Operations E-2-8 E2-8 0.00 - -

TXI Operations E2-22 E2-22 7.90 3.45 7.9

2.3.3.1.2.4. DFW 2018 EI Summary

The future case EI is composed of two datasets, hourly average 3Q2008 for the ARD sources and 

2008 OSD for the remainder of the point sources. The 2012 future base is built upon these 

datasets by incorporating the changes expected due to growth, emission caps, and on-the-books 

controls. Table 2-18: Detailed NOX 2018 Emissions Summary by Region provides a 2012 

emissions summary.

Table 2-18: Detailed NOX 2018 Emissions Summary by Region

Region Projection Affected Sources

2012 

STARS 

NOX,

tpd

2013 

AMPD 

NOX,

tpd

2018

NOX

Projection, 

tpd

DFW CAIR EGUs 7.23 16.77

DFW Controls Midlothian Kilns 6.47 14.91

DFW Growth NEGUs 23.73 23.17
Region Projection Affected Sources

2012 

STARS 

NOX,

tpd

2013 

AMPD 

NOX,

tpd

2018

NOX

Projection, 

tpd

HGB MECT OSD point sources 52.48 75.35

HGB MECT Growth under the cap 1.78

HGB MECT AMPD point sources 28.72 46.22

HGB MECT New EGU Growth 2.42

HGB Growth/bank NEGUs 17.62 20.73

Rest of TX CAIR AMPD point sources 375.70 420.01

Rest of TX Growth OSD point sources 388.7 412.94

2.3.4. 2018 Regional (Outside of Texas) Point Sources

Regional emissions include states outside of Texas within the modeling domain, offshore Gulf of 

Mexico, and the parts of Mexico and Canada within the modeling domain.

2.3.4.1. States Outside of Texas

2.3.4.1.1. EGUs

The TCEQ distinguishes between EGUs and AMPD units. Not all EGUs are AMPD units, e.g., 

true cogeneration units are not AMPD units, but large cogeneration units that supply more than 

one-third of their electricity to the public electrical grid are AMPD units. Non-AMPD EGUs are 

treated as NEGUs. This is the same definition that the EPA applies to EGUs for CAIR purposes, 

i.e., an EGU, as defined by CAIR, is an AMPD unit.

To develop projection base USA AMPD, the TCEQ compiled and maintains a USA cross 

reference file that links AMPD identifiers to a record NEI identifiers, where the NEI also carries 

FIPS, plant, stack, point, location parameters, stack parameters, and (in some instances) site 

name. Thus, the USA AMPD-to-NEI cross reference provides enough information to make an 

AFS record without matching another (OSD type) emission record. The USA cross reference file 

matches a high percentage (over 99%) of the USA AMPD units. The cross reference is based on a 

variety of sources, primarily the NEI which, for 2011, also provided ORIS and BOILER 

identifiers, For these points sources, TCEQ was able to attach total heat input values from the 

(same year) 2011 AMPD and, from the composite, compute emission-to-heat input ratios for 

many EGUs in the 2011 NEI. TCEQ used these emission ratios to compute hourly pollutant 

emissions for selected points in the 2013 projection base year using the hourly heat inputs. For 

the unmatched points, TCEQ distributed the unmatched NOX emissions proportionally to all the 

matched points within the respective state.

To develop the 2018 future case EGUs for states outside of Texas, the TCEQ used CAIR Phase II

for states subject to the CAIR program and 2013 AMPD data. TCEQ used the CAIR state budgets 

specified in 40 CFR Part 96 for each state and a historical trend analysis to determine the future 

year state emissions. The historical trend analysis looked at which states where below or above 

their assigned state budgets to better estimate future year state emissions for CAIR states.

Scaling statewide emissions to match the assigned cap took into account the effect of seasonal 

variation.
The TCEQ did not account for growth outside Texas. An alternative to TCEQ’s approach that

includes growth and controls is to use EGU emission projection tools such as the EPA’s IPM or 

the Eastern Regional Technical Advisory Committee (ERTAC) EGU Forecasting Tool. A 

comparison was made to the total state emissions predicted by IPM and ERTAC EGU 

Forecasting Tool for 2018 with TCEQ’s method and it was found that TCEQ’s method resulted in 

a more conservative regional emissions total with most of the CAIR regional cap (93%) have 

been modeled.

Table 2-19: 2018 Modeled Emissions for States in the Modeling Domain gives the future year 

emissions along with modeled CAIR (ozone or annual) emissions, where applicable, for each 

state outside Texas in the modeling domain. An empty cell indicates CAIR is not applicable for 

that state.

Table 2-19: 2018 Modeled Emissions for States in the Modeling Domain

State Ozone Season CAIR Cap,

NOX tons per ozone season

Annual CAIR Cap,

NOX tpy

2018 Modeled 

Emissions,

NOX tpd

AL 22095.52 146.45

AR 17339.36 117.53

AZ 155.72

CA 14.59

CO 131.21

CT 578.983 4.12

DC 94 0.67

DE 912.096 6.24

FL 27081.29 182.16

GA 35599.31 103.67

IA 15253.83 106.55

ID 0.74

IL 18671.13 126.10

IN 39273 258.63

KS 86.80

KY 30587 201.93

LA 17788.95 121.20

MA 1607.635 11.38

MD 5303.099 36.61

ME 1.34

MI 24142 160.86

MN 73.63

MO 22231 153.14

MS 11320.76 80.17

MT 46.89

NC 22633.86 157.38

ND 128.82
State Ozone Season CAIR Cap,

NOX tons per ozone season

Annual CAIR Cap,

NOX tpy

2018 Modeled 

Emissions,

NOX tpd

NE 79.62

NH 4.93

NJ 2679.769 18.60

NM 162.78

NV 27.56

NY 10856.86 73.04

OH 37150.73 248.28

OK 160.48

OR 12.34

PA 57246.25 378.14

RI 1.92

SC 7361.666 51.00

SD 32.82

TN 11252.72 74.80

UT 163.01

VA 13328 91.38

VT 0.51

WA 25.35

WI 10864.1 73.93

WV 25470.17 172.27

WY 134.45

2.3.4.1.2. NEGUs

For 2018 NEGUs for other states, the TCEQ used the EPA’s 2018 non-IPM (non-EGU) files from 

EPA’s 2018 Emissions Modeling Platform18. The non-IPM portion of the platform consists of 

several emissions files including the primary points file containing emissions for all states, plus 

additional files for ethanol and biodiesel plants and cement kilns. These files were already grown 

and controlled, but for the most part represent the 2011 NEI for the country with federal rules 

and some state rules applied. After extracting Texas from the list, the TCEQ generated an AFSformatted file, including all necessary and relevant modeling parameters for EPS3 processing.

The associated temporal allocation file was utilized to create the daily temporal distribution. A 

June day was selected to represent a typical ozone season day. Summary files provided by EPA 

contain individual state totals for NEGU (non-IPM) emissions. These summaries can be found 

at the EPA Emissions Inventory website at 

ftp://ftp.epa.gov/EmisInventory/2011v6/v1platform/reports/2018_emissions/.

Table 2-20: 2018 Regional States Emissions Summary provides an overall summary of the 2018

emissions for all the states within the modeling domain (continental USA), outside of Texas

 18 From EPA’s Emissions Modeling Clearinghouse page: http://www.epa.gov/ttnchie1/emch/, the TCEQ 

chose the link “2011 and 2018 Emissions Modeling Platform Data Files and Summaries” which takes the 

reader to ftp://ftp.epa.gov/EmisInventory/2011v6/v1platform/2018emissions/
Table 2-20: 2018 Regional States Emissions Summary

Model Year Source 

Category

NOX

Emissions, 

tpd

VOC 

Emissions, 

tpd

CO 

Emissions, 

tpd

2006 Baseline EGU 7757 88 885

2018 Future Case EGU 4602 76 1673

2006 Baseline NEGU19 4539 2457 5953

2018 Future Case NEGU 3820 2248 4883

2.3.5. Offshore, Mexico, and Canada

For lack of projections data, the 2018 EIs for the Gulf of Mexico offshore area, Mexico, and 

Canada were the same as those used in the 2006 baseline and the base case, as described in 

previous sections. The TCEQ used the EPA’s 2018 modeling platform for Mexico. These files 

were already grown, based on 1999 NEI.

2.3.6. Summary of Future Case Point Source Data Files

The point source emission files that were processed with EPS3 for CAMx are presented in Table 

2-21: AFS Files for the 2018 Future Case Episode. The regional AFS file for the GWEI contains 

monthly emissions for June only and the regional AFS file for Canadian emissions contains 

annual emissions. The version number on each dataset indicates a change from the previous 

version (e.g., “v8”). The FTP download website for these files is 

ftp://amdaftp.tceq.texas.gov/pub/TX/ei/fy2018/point.

Table 2-21: AFS Files for the 2018 Future Case Episode

Area AFS Point Source Emissions Dataset Hourly Daily Special 

Texas afs.ard_JUN2SEP_2018_MECT_NOX_aver_day_RPOlcp_v8 X

Texas afs.ard_JUN2SEP_2018_nonNOX_aver_day_RPOlcp_v9 X 1

Texas afs.ard_JUN2SEP_2018_CAIR_NOX_aver_day_RPOlcp_v10 X

Texas afs.osd_no_controls_grown_to_2018.RPOlcp_v8 X

Texas afs.2018_HECT_cap_n_trade_HarrisCo_2012_basis_all_pts_v3 X

Texas afs.osd_hgb_dfw_growth_with_bank_v12 X

Texas afs.osd_new_egus_2013_to_2018_v7 X

Texas afs.osd_mect_2018_based_on_2012_RPOlcp_v8 X

Texas afs.osd_2018_CAIR_NOX_records_v11 X

Texas afs.midlokilns_2018_NOX_emissions.RPOlcp X

Regional afs.amp_USA_JUN2SEP_2018_CAIR_avg_day_all_pols_RPOlcp X

Regional afs.2018_USA_noTX_noEGU.RPOlcp X

Regional afs.gwei.2008.lcpRPO Monthly

Regional afs.Mexico_2018_from_EPA2011Platform_1999NEI.RPOlcp X

Regional afs.canada_2006_all_pols.RPOlcp Annual

 19 Based on EPA’s 2008 NEI.
Table 2-22: 2018 Future Case Point Source Emissions Summary summarizes the future case 

emissions. These tabulated emissions are AFS totals input to EPS3. CAMx input values may 

differ. The U.S. minus Texas column includes some points outside the modeling domain. The TX 

minus DFW column includes some points in Texas outside the modeling domain. As noted 

earlier in Section 2.1.1.4.1, VOC emission totals include acetone and ethane.

Table 2-22: 2018 Future Case Point Source Emissions Summary

Emission Source

DFW 

NOX

(tpd)

DFW 

VOC 

(tpd)

TX minus 

DFW 

NOX (tpd)

TX minus 

DFW 

VOC (tpd) 

U.S. minus 

TX NOX

(tpd)

U.S. minus 

TX VOC 

(tpd)

NEGUs (OSD) 40.8 47.3 523.3 461.9 3820.4 2248.1

EGUs (ARD) 16.8 4.4 466.2 27.3 4601.8 76.5

2.4 2018 Point Source Control Strategy and/or Sensitivity Analyses

Existing controls with compliance dates that were in the past, were between the baseline and the 

projection base year, or were included in the projection base year, were modeled in the future 

case identified above. Any new control strategies, RACT, RACM, other rules, potential rules, or 

sensitivity analyses that are modeled are applied on top of the future case modeling in order to 

determine the efficacy in the future. The point source sensitivity analyses performed for this 

DFW attainment demonstration are (1) a DERC Flow Control sensitivity, and (2) a Cross State 

Air Pollution Rule (CSAPR) sensitivity.

3. ON-ROAD MOBILE SOURCE MODELING EMISSIONS DEVELOPMENT

3.1 On-Road Mobile Source Emissions Inventories for 10-County DFW

This section provides a brief overview of the development of the 10-county DFW area on-road 

mobile source emissions inventory files that were input into the photochemical model for the 

2006 base case, the 2006 baseline case, and the 2018 future case. The on-road emission 

inventories were developed with the 2014 version of the Motor Vehicle Emission Simulator 

(MOVES2014) model.

The on-road emissions inventory datasets were developed under contract by the North Central 

Texas Council of Governments (NCTCOG) and the Texas Transportation Institute (TTI). 

NCTCOG developed 2006 and 2018 link-based on-road emission estimates using MOVES2014

and travel demand model (TDM) output for the DFW area as the basis for vehicle miles traveled 

(VMT) estimates. MOVES2014 outputs nitrogen oxide (NO), nitrogen dioxide (NO2), and 

nitrous acid (HONO), which are components of oxides of nitrogen (NOX). The tables in this 

section report NO, NO2, and NOX separately. Due to space limitations, HONO is not reported

separately, but MOVES2014 calculates it as 0.8% of total NOX emissions. For both the 2006 

base case and the 2018 future case, school and summer season on-road emission inventories 

were developed for the four day types of weekday (i.e., Monday through Thursday average), 

Friday, Saturday, and Sunday. For the on-road category, base case and baseline emissions are 

the same.

Table 3-1: VMT and Emissions by Day Type for 2006 DFW On-Road Inventory and Table 3-2: 

VMT and Emissions by Day Type for 2018 DFW On-Road Inventory provide summaries of the 

total VMT, NO, NO2, NOX, volatile organic compound (VOC), and carbon monoxide (CO) 

emissions for the 10-county DFW area for each day type for the 2006 base case and 2018 future 
case, respectively. As shown, Fridays have the highest total VMT of the week, while Saturdays 

and Sundays have the lowest total daily VMT. While overall VMT increases with future growth, 

total emissions decrease from 2006 to 2018 as a result of more stringent emissions standards 

for newer vehicles entering the fleet, combined with the simultaneous attrition of older, higheremitting vehicles. Consistent with current federal and state rules, the on-road inventories from 

NCTCOG include the benefits of:

• reformulated gasoline (RFG) in Collin, Dallas, Denton, and Tarrant counties;

• low Reid vapor pressure (RVP) gasoline in Ellis, Johnson, Kaufman, Parker, Rockwall, and 

Wise counties;

• the inspection and maintenance (I/M) Program in Collin, Dallas, Denton, Ellis, Johnson, 

Kaufman, Parker, Rockwall, and Tarrant counties; and

• Texas low emission diesel (TxLED) fuel for all 10 DFW area counties.

Table 3-1: VMT and Emissions by Day Type for 2006 DFW On-Road Inventory

Season and

Day Type

Vehicle Miles

Traveled

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Summer Weekday 158,661,182 262.07 19.92 284.27 116.50 1,315.46

Summer Friday 175,991,883 270.83 21.05 294.23 120.22 1,425.40

Summer Saturday 143,694,618 191.61 15.37 208.65 107.88 1,227.77

Summer Sunday 118,574,926 174.06 13.51 189.08 101.60 1,074.31

School Weekday 159,475,888 262.64 19.98 284.90 116.80 1,320.26

School Friday 174,982,511 269.33 20.92 292.59 119.89 1,419.01

School Saturday 141,989,731 189.25 15.17 206.07 107.37 1,216.12

School Sunday 117,230,204 172.04 13.34 186.88 101.19 1,065.03

Table 3-2: VMT and Emissions by Day Type for 2018 DFW On-Road Inventory

Season and

Day Type

Vehicle Miles

Traveled

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Summer Weekday 221,520,532 101.77 16.96 119.69 62.20 989.88

Summer Friday 245,575,338 104.30 17.27 122.56 63.73 1,079.37

Summer Saturday 196,388,570 77.25 12.34 90.32 58.73 923.96

Summer Sunday 164,875,239 72.49 11.63 84.81 56.67 811.78

School Weekday 222,641,360 102.01 17.00 119.97 62.32 993.96

School Friday 245,090,234 103.97 17.22 122.16 63.67 1,077.47

School Saturday 194,774,800 76.66 12.25 89.63 58.59 918.23

School Sunday 162,559,712 71.63 11.49 83.79 56.46 803.01

Even though all of the day type on-road inventory datasets were used for photochemical model 

input, only the summer weekday emissions will be detailed here. For the 2006 base case and 

2018 future case, the summaries of the VMT, NO, NO2, NOX, VOC, and CO emissions for each of 

the 10 counties in the DFW area are shown in Table 3-3: VMT and Emissions by County for 

2006 DFW On-Road Inventory and Table 3-4: VMT and Emissions by County for 2018 DFW 

On-Road Inventory, respectively.
Table 3-3: VMT and Emissions by County for 2006 DFW On-Road Inventory

DFW Area

County

Vehicle Miles

Traveled

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Collin 16,785,092 24.50 1.91 26.62 11.53 124.25

Dallas 64,064,555 98.08 7.54 106.47 47.02 546.96

Denton 13,812,713 23.16 1.75 25.11 10.04 103.14

Ellis 5,460,324 14.92 1.05 16.10 4.46 49.67

Johnson 4,472,201 9.14 0.68 9.89 3.56 42.89

Kaufman 4,557,637 11.74 0.85 12.70 3.34 40.09

Parker 3,903,299 10.50 0.73 11.33 3.03 32.19

Rockwall 1,863,468 3.93 0.29 4.25 1.61 17.98

Tarrant 41,236,585 59.81 4.65 64.98 29.99 333.12

Wise 2,505,308 6.29 0.47 6.81 1.89 25.18

Total 158,661,182 262.07 19.92 284.27 116.50 1,315.46

Table 3-4: VMT and Emissions by County for 2018 DFW On-Road Inventory

DFW Area

County

Vehicle Miles

Traveled

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Collin 27,052,719 10.02 1.58 11.69 7.07 112.48

Dallas 82,293,890 33.67 5.07 39.05 22.46 383.98

Denton 21,999,802 9.48 1.60 11.16 5.95 88.13

Ellis 8,530,620 7.28 1.57 8.92 2.57 33.96

Johnson 6,274,070 3.83 0.72 4.59 1.94 26.63

Kaufman 7,245,585 5.54 1.22 6.82 1.92 27.74

Parker 5,801,400 5.92 1.32 7.31 1.97 26.26

Rockwall 2,795,026 1.60 0.30 1.92 0.91 11.65

Tarrant 55,850,317 22.16 3.20 25.57 16.43 263.30

Wise 3,677,105 2.27 0.38 2.68 0.97 15.76

Total 221,520,532 101.77 16.96 119.69 62.20 989.88

Summaries for 2006 and 2018 of the VMT, NO, NO2, NOX, VOC, and CO emissions for the 

gasoline and diesel fuel source use type (SUT) combinations from the MOVES2014 model are 

presented in Table 3-5: VMT and Emissions by Vehicle Type for 2006 DFW On-Road Inventory

and Table 3-6: VMT and Emissions by Vehicle Type for 2018 DFW On-Road Inventory.

Table 3-5: VMT and Emissions by Vehicle Type for 2006 DFW On-Road Inventory

Fuel and Source

Use Type Combination VMT NO(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Gasoline - Motorcycle 117,737 0.09 0.00 0.09 1.00 2.44

Gasoline - Passenger Car 117,291,095 82.50 7.83 91.06 65.04 746.70

Gasoline - Passenger Truck 22,776,540 34.59 2.99 37.88 26.72 342.96

Gasoline - Light Commercial Truck 6,844,055 11.16 0.99 12.25 8.54 109.29

Gasoline - Transit Bus 447 0.00 0.00 0.00 0.00 0.02
Fuel and Source

Use Type Combination VMT NO(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Gasoline - School Bus 13,989 0.09 0.00 0.09 0.06 0.96

Gasoline - Refuse Truck 4,527 0.03 0.00 0.03 0.01 0.33

Gasoline - Single Unit Short-Haul Truck 1,171,839 4.52 0.25 4.81 1.71 42.80

Gasoline - Single Unit Long-Haul Truck 161,348 0.57 0.03 0.61 0.20 4.76

Gasoline - Motor Home 143,841 0.67 0.03 0.71 0.25 6.43

Gasoline - Combination Short-Haul Truck 1,016 0.01 0.00 0.01 0.00 0.09

Diesel - Passenger Car 446,134 0.36 0.02 0.38 0.35 5.96

Diesel - Passenger Truck 322,243 1.12 0.07 1.20 0.35 4.06

Diesel - Light Commercial Truck 393,137 1.56 0.10 1.67 0.46 4.01

Diesel - Intercity Bus 163,006 3.07 0.19 3.29 0.19 0.91

Diesel - Transit Bus 45,423 0.69 0.04 0.73 0.04 0.27

Diesel - School Bus 169,433 1.48 0.09 1.58 0.22 0.63

Diesel - Refuse Truck 108,653 1.64 0.10 1.75 0.10 0.55

Diesel - Single Unit Short-Haul Truck 2,593,132 17.14 1.04 18.33 2.35 7.79

Diesel - Single Unit Long-Haul Truck 363,000 2.20 0.13 2.36 0.32 1.03

Diesel - Motor Home 83,758 0.71 0.04 0.76 0.11 0.28

Diesel - Combination Short-Haul Truck 2,245,963 32.40 1.98 34.65 1.94 10.90

Diesel - Combination Long-Haul Truck 3,200,863 65.49 3.99 70.04 6.53 22.30

Total 158,661,182 262.07 19.92 284.27 116.50 1,315.5

Table 3-6: VMT and Emissions by Vehicle Type for 2018 DFW On-Road Inventory

Fuel and Source

Use Type Combination VMT NO(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Gasoline - Motorcycle 155,855 0.10 0.00 0.10 1.17 2.00

Gasoline - Passenger Car 154,569,516 24.66 2.77 27.65 33.58 565.15

Gasoline - Passenger Truck 29,925,824 14.26 1.57 15.96 12.10 214.56

Gasoline - Light Commercial Truck 18,434,314 9.53 1.05 10.67 7.95 140.22

Gasoline - Transit Bus 477 0.00 0.00 0.00 0.00 0.01

Gasoline - School Bus 14,914 0.06 0.00 0.06 0.05 0.84

Gasoline - Refuse Truck 5,999 0.03 0.00 0.03 0.01 0.31

Gasoline - Single Unit Short-Haul Truck 1,552,802 1.04 0.12 1.17 0.70 21.77

Gasoline - Single Unit Long-Haul Truck 213,802 0.12 0.02 0.14 0.08 2.50

Gasoline - Motor Home 190,603 0.37 0.03 0.40 0.18 4.41

Gasoline - Combination Short-Haul Truck 1,683 0.00 0.00 0.00 0.00 0.03

Diesel - Passenger Car 1,285,165 0.13 0.05 0.18 0.10 4.82

Diesel - Passenger Truck 542,270 0.79 0.15 0.95 0.19 2.49

Diesel - Light Commercial Truck 1,032,692 1.60 0.25 1.87 0.44 5.74

Diesel - Intercity Bus 173,786 1.41 0.14 1.55 0.11 0.57

Diesel - Transit Bus 48,427 0.26 0.03 0.29 0.02 0.16

Diesel - School Bus 180,639 0.70 0.07 0.78 0.13 0.46

Diesel - Refuse Truck 143,976 0.54 0.09 0.64 0.04 0.26

Diesel - Single Unit Short-Haul Truck 3,436,158 3.74 1.28 5.06 0.44 3.18

Diesel - Single Unit Long-Haul Truck 481,011 0.45 0.16 0.62 0.05 0.41

Diesel - Motor Home 110,988 0.34 0.04 0.38 0.06 0.19
Fuel and Source

Use Type Combination VMT NO(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Diesel - Combination Short-Haul Truck 3,719,186 9.29 2.20 11.59 0.61 4.20

Diesel - Combination Long-Haul Truck 5,300,445 32.33 6.95 39.59 4.21 15.61

Total 221,520,532 101.77 16.96 119.69 62.20 989.88

The MOVES2014 run specification files used to develop these inventories for 2006, along with 

detailed reports and summary output data, can be found on the 2006 DFW on-road FTP site at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/DFW/mvs/2006/. The MOVES2014 run 

specification files used to develop these inventories for 2018, along with detailed reports and 

summary output data, can be found on the 2018 DFW on-road FTP site at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/DFW/mvs/2018/.

3.2 On-Road Mobile Source Emissions Processing

The on-road emissions inventory data provided by NCTCOG were prepared for input into the 

photochemical model using version 3 of the Emissions Processor System (EPS3). When input 

into EPS3, the inventory data are in a readable text-based format. However, the emissions data 

are maintained in a binary format within EPS3. Table 3-7: EPS3 Modules for Processing OnRoad Emissions summarizes the EPS3 modules that were used to process the 10-county DFW 

on-road inventories.

Table 3-7: EPS3 Modules for Processing On-Road Emissions

EPS3

Module Description

LBASE Spatially allocate link-based emissions among grid cells.

PREAM Prepare non-link “roadway type” emissions for further processing.

PREPNT Prepare stationary extended idling emissions for further processing.

CNTLEM Apply controls to model strategies, apply adjustments, etc.

TMPRL Apply temporal profiles to extended idling emissions.

SPCEMS Chemically speciate VOC emissions into olefins, paraffins, etc.

GRDEM Sum emissions by grid cell for photochemical model input.

MRGUAM Merge and adjust multiple gridded files for photochemical model input.

The MOVES2014 model only estimates extended idling emissions for the diesel fuel 

combination long-haul truck category. Using a combination of SAS and LINUX code, the 

extended idling emissions were aggregated into a 10-county total and spatially assigned to 

known truck stop locations. The extended idling emissions were then processed through EPS3 

as if they were stationary low-level point sources. The summer weekday extended idling 

emissions by county are presented below in Table 3-8: 2006 and 2018 DFW Area Long-Haul 

Truck Extended Idling Emissions. Greater detail on heavy-duty vehicle idling activity specific to 

Texas metropolitan areas can be found in a report entitled Heavy-Duty Vehicle Idle Activity and 

Emissions Characterization Study, which is available at 

http://www.tceq.texas.gov/airquality/airmod/project/pj_report_mob.html.
Table 3-8: 2006 and 2018 DFW Area Long-Haul Truck Extended Idling Emissions

Calendar

Year

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

2006 9.88 0.60 10.57 3.75 4.90

2018 9.66 3.29 13.06 2.85 6.77

3.2.1. Texas Low Emission Diesel Fuel Benefits

Based on the EPA memorandum Texas Low Emission Diesel (LED) Fuel Benefits (September 

27, 2001), a 4.8% NOX TxLED reduction should be claimed for 2002-and-newer diesel vehicles 

and a 6.2% NOX TxLED reduction should be claimed for 2001-and-older diesel vehicles. In 

order to determine the specific TxLED adjustment factors that should apply to each of the twelve 

diesel fuel source use types, MOVES2014 model runs were performed to determine NOX

emissions rates by model year. By using these data, the 4.8% and 6.2% TxLED reduction factors 

were weighted according to the model year specific diesel NOX emission rates. The TCEQ TxLED 

factors FTP site at ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/Statewide/mvs/txled/ contains 

more detail on this analysis. The resulting TxLED adjustment factors and benefits for both 2006 

and 2018 are summarized in Table 3-9: 2006 DFW On-Road TxLED Benefits by Vehicle Type

and Table 3-10: 2018 DFW On-Road TxLED Benefits by Vehicle Type, respectively. The TxLED

adjustment factors were incorporated by NCTCOG and TTI into the on-road inventories by postprocessing the MOVES2014 diesel fuel source use type NOX emission rates.

Table 3-9: 2006 DFW On-Road TxLED Benefits by Vehicle Type

Diesel Fuel

Source Use Type

NOX

Reduction

Adjustment

Factor

NOX Benefit

(tpd)

Passenger Car 6.07% 0.9393 0.02

Passenger Truck 5.56% 0.9444 0.07

Light Commercial Truck 5.88% 0.9412 0.10

Intercity Bus 5.98% 0.9402 0.21

Transit Bus 5.93% 0.9407 0.05

School Bus 5.91% 0.9409 0.10

Refuse Truck 5.82% 0.9418 0.11

Single Unit Short-Haul Truck 5.41% 0.9459 1.05

Single Unit Long-Haul Truck 5.29% 0.9471 0.13

Motor Home 5.71% 0.9429 0.05

Combination Short-Haul Truck 5.89% 0.9411 2.17

Combination Long-Haul Truck 5.92% 0.9408 4.41

Total 8.46

Table 3-10: 2018 DFW On-Road TxLED Benefits by Vehicle Type

Diesel Fuel

Source Use Type

NOX

Reduction

Adjustment

Factor

NOX Benefit

(tpd)

Passenger Car 4.99% 0.9501 0.01

Passenger Truck 5.04% 0.9496 0.05

Light Commercial Truck 5.32% 0.9468 0.10
Diesel Fuel

Source Use Type

NOX

Reduction

Adjustment

Factor

NOX Benefit

(tpd)

Intercity Bus 5.65% 0.9435 0.09

Transit Bus 5.62% 0.9438 0.02

School Bus 5.63% 0.9437 0.05

Refuse Truck 5.30% 0.9470 0.04

Single Unit Short-Haul Truck 4.89% 0.9511 0.26

Single Unit Long-Haul Truck 4.88% 0.9512 0.03

Motor Home 5.36% 0.9464 0.02

Combination Short-Haul Truck 5.18% 0.9482 0.63

Combination Long-Haul Truck 5.21% 0.9479 2.18

Total 3.48

3.3 10-County DFW Photochemical Modeling Input

The summer weekday on-road emissions by county that were input into the photochemical 

model are summarized below in Table 3-11: 2006 DFW Area Summer Weekday On-Road 

Emissions by County and Table 3-12: 2018 DFW Area Summer Weekday On-Road Emissions by 

County. These on-road inventory summaries are a combination of running exhaust, evaporative, 

off-network, and extended idling emissions. Differences by individual counties between these 

figures and those referenced above in Table 3-3 and Table 3-4 are due to the spatial reallocation 

of extended idling emissions presented above in Table 3-8. However, the 10-county total onroad emission estimates do not differ.

Table 3-11: 2006 DFW Area Summer Weekday On-Road Emissions by County

DFW Area

County

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Collin 24.69 1.92 26.82 11.60 124.34

Dallas 99.81 7.65 108.32 47.68 547.82

Denton 22.65 1.72 24.57 9.85 102.89

Ellis 13.65 0.97 14.74 3.98 49.04

Johnson 8.67 0.65 9.39 3.38 42.65

Kaufman 11.59 0.84 12.53 3.28 40.01

Parker 10.30 0.72 11.11 2.97 32.10

Rockwall 4.15 0.30 4.48 1.69 18.09

Tarrant 60.38 4.68 65.58 30.21 333.40

Wise 6.19 0.46 6.71 1.86 25.13

Total 262.07 19.92 284.27 116.50 1,315.46

Table 3-12: 2018 DFW Area Summer Weekday On-Road Emissions by County

DFW Area

County

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Collin 10.25 1.65 12.00 7.13 112.63

Dallas 35.77 5.78 41.89 23.08 385.45

Denton 9.26 1.53 10.88 5.89 87.99
DFW Area

County

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Ellis 5.79 1.06 6.90 2.13 32.91

Johnson 3.13 0.48 3.64 1.73 26.12

Kaufman 5.21 1.11 6.37 1.82 27.49

Parker 5.33 1.12 6.51 1.81 25.88

Rockwall 1.82 0.38 2.22 0.98 11.80

Tarrant 23.07 3.51 26.80 16.70 263.94

Wise 2.13 0.34 2.49 0.93 15.67

Total 101.77 16.96 119.69 62.20 989.88

The total 10-county DFW on-road emissions input to the photochemical model by day type are 

summarized below in Table 3-13: 2006 DFW Area On-Road Emissions by Season and Day Type

and Table 3-14: 2018 DFW Area On-Road Emissions by Season and Day Type. Slight differences 

by day type between these figures and those presented in Table 3-1 and Table 3-2 are due to the

on-road emission inventories being developed in Central Daylight Time (CDT), but processed 

for photochemical model input in Central Standard Time (CST). For example, the 11 PM – 12 

AM CST emissions on a Friday evening are based on 12-1 AM CDT emissions from a Saturday.

Table 3-13: 2006 DFW Area On-Road Emissions by Season and Day Type

Season and

Day Type

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Summer Weekday 262.07 19.92 284.27 116.50 1,315.46

Summer Friday 271.10 21.09 294.54 120.41 1,430.74

Summer Saturday 191.89 15.39 208.95 107.91 1,228.21

Summer Sunday 173.23 13.42 188.15 101.29 1,066.20

School Weekday 262.64 19.98 284.90 116.80 1,320.26

School Friday 269.57 20.97 292.87 120.07 1,424.23

School Saturday 189.54 15.19 206.38 107.40 1,216.60

School Sunday 171.25 13.25 185.99 100.89 1,057.09

Table 3-14: 2018 DFW Area On-Road Emissions by Season and Day Type

Season and

Day Type

NO

(tpd)

NO2

(tpd)

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

Summer Weekday 101.77 16.96 119.69 62.20 989.88

Summer Friday 104.40 17.28 122.67 63.80 1,083.31

Summer Saturday 77.34 12.36 90.42 58.74 924.25

Summer Sunday 72.27 11.60 84.54 56.58 806.43

School Weekday 102.01 17.00 119.97 62.32 993.96

School Friday 104.06 17.23 122.27 63.73 1,081.33

School Saturday 76.75 12.26 89.72 58.60 918.48

School Sunday 71.43 11.46 83.55 56.37 797.80

The EPS3 message files for 2006 DFW along with the gridded files input into the photochemical 

model are available on the TCEQ DFW 2006 FTP site at 
ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/DFW/eps3/2006/. The EPS3 message files for 

2018 DFW along with the gridded files input into the photochemical model are available on the 

2018 DFW FTP site at ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/DFW/eps3/2018/.

Similar on-road mobile EPS3 message and gridded files for the Texas-only portion of the 

modeling domain are available for both 2006 and 2018 at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/Statewide/eps3/2006/, and 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/Statewide/eps3/2018/, respectively.

Similar on-road mobile EPS3 message and gridded files for the non-Texas U.S. portions of the 

modeling domain are available for both 2006 and 2018 at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/USA/eps3/2006/, and 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/USA/eps3/2018/, respectively.

Similar 2006 and 2018 on-road mobile EPS3 message and gridded files for the Canada and 

Mexico portions of the modeling domain are available at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/CAN/eps3/, and 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/MEX/eps3/, respectively.

3.4 Attainment Demonstration Motor Vehicle Emissions Budget

By definition, the future case on-road NOX and VOC emission estimates input into the final 

attainment demonstration photochemical modeling run should establish the motor vehicle 

emissions budget (MVEB). The 2018 summer weekday on-road emissions are the most 

representative season and day type for this purpose, and are presented below in Table 3-15: 

Attainment Demonstration MVEB for the 10-County DFW Area. As shown, these 2018 figures 

match those provided by NCTCOG as summarized above in Table 3-2, Table 3-4, and Table 3-6. 

No emission reduction credits were taken for local transportation control measures (TCMs) and

voluntary mobile source emission reduction program (VMEP) strategies.

Table 3-15: Attainment Demonstration MVEB for the 10-County DFW Area

10-County DFW Area

On-Road Emissions

NOX

(tpd)

VOC

(tpd)

2018 On-Road Inventory From NCTCOG (Table 3-2)

Includes RFG, Low RVP, I/M, and TxLED

119.69 62.20

The following pages contain graphical plots of the spatial and temporal distribution of 2006 and 

2018 on-road summer weekday NOX and VOC emissions for the greater DFW area. The plots 

show that the morning rush hour peak is appropriately allocated to 6-7 AM CST, which is 7-8 

AM CDT. These plots are respectively entitled Figure 3-1: 2006 Summer Weekday DFW OnRoad NOX Emissions Distribution, Figure 3-2: 2006 Summer Weekday DFW On-Road VOC 

Emissions Distribution, Figure 3-3: 2018 Summer Weekday DFW On-Road NOX Emissions 

Distribution, and Figure 3-4: 2018 Summer Weekday DFW On-Road VOC Emissions 

Distribution.
Figure 3-1: 2006 Summer Weekday DFW On-Road NOX Emissions Distribution
Figure 3-2: 2006 Summer Weekday DFW On-Road VOC Emissions Distribution
Figure 3-3: 2018 Summer Weekday DFW On-Road NOX Emissions Distribution
Figure 3-4: 2018 Summer Weekday DFW On-Road VOC Emissions Distribution
3.5 On-Road Mobile Source Emissions Inventories for Non-DFW Areas

For the Texas counties outside of the DFW area, on-road emissions were developed by TTI using 

HPMS data as the basis for VMT estimates. Both school and summer season emission estimates 

were developed for the four day types of weekday, Friday, Saturday, and Sunday. Hourly 

emission rates from MOVES2014 were coupled with county-level VMT estimates by roadway 

type for 2006 and 2018. More detail on the development of these HPMS-based on-road datasets 

can be found on the TCEQ Texas 2006 FTP site and the TCEQ Texas 2018 FTP site at 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/Statewide/mvs/2006/, and 

ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/Statewide/mvs/2018/, respectively.

On-road emission estimates for non-Texas states within the photochemical modeling domain 

were developed for both 2006 and 2018 using default runs from the MOVES2014 model, which 

is available on EPA’s MOVES web page at http://www.epa.gov/otaq/models/moves/. For both 

2006 and 2018, default on-road emissions were estimated for the July weekday option available 

with MOVES2014. These summer weekday emission totals were then adjusted with EPS3 to 

obtain inputs for the other season and day type combinations. More detail on the development 

of the MOVES2014 on-road datasets can be found on the TCEQ U.S. 2006 FTP site and the 

TCEQ U.S. 2018 FTP site at ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/USA/mvs/2006/, 

and ftp://amdaftp.tceq.texas.gov/pub/Mobile_EI/USA/mvs/2018/, respectively.

More detail on this analysis is documented in a presentation entitled Using the MOVES Model 

in Inventory Mode to Develop Regional On-Road Emission Inputs for Air Quality Modeling 

Applications, which was presented at an EPA workshop in June of 2011 and is available at 

http://www.epa.gov/otaq/models/moves/conference2011/inventory-regional-moves-2011.pdf. 

A summary of the different on-road emission estimation approaches by geographic area taken 

for this DFW SIP revision is provided in Table 3-16: On-Road Inventory Development 

Methodologies by Geographic Area.

Table 3-16: On-Road Inventory Development Methodologies by Geographic Area

On-Road Inventory

Development Parameter

DFW

Area

Non-DFW

Texas Counties

Non-Texas

States and Counties

VMT

Source TDM HPMS MOVES2014Defaults

VMT

Resolution

Roadway Links

From TDM

19 Roadway

Types

12 Roadway

Types

Season Types School and Summer School and Summer School and Summer

Day

Types

Weekday, Friday,

Saturday, and Sunday

Weekday, Friday,

Saturday, and Sunday

Weekday, Friday, 

Saturday, and Sunday

Hourly Variation in

VMT? Yes Yes Yes

Roadway Speed

Distribution

Varies by Hour

and Link

Varies by Hour and

Roadway Type

MOVES2014

Defaults

Spatial

Resolution Excellent VeryGood Good

Temporal

Resolution Excellent VeryGood Good

MOVES Fuel and

Source Use Types

Gasoline and Diesel

13 Source Use Types

Gasoline and Diesel

13 Source Use Types

Gasoline and Diesel

13 Source Use Types
4. NON-ROAD, OFF-ROAD, AND AREA SOURCE MODELING EMISSIONS 

4.1 Oil and Gas Production and Drilling Emission Inventory Development

Oil and gas production emission estimates were developed based on activity data from the 

Railroad Commission of Texas (RRC) multiplied by emission factors for specific operations and 

types of equipment from an Eastern Research Group (ERG) study entitled Characterization of 

Oil and Gas Production Equipment and Develop a Methodology to Estimate Statewide 

Emissions. This report is available on the TCEQ Air Quality Research and Contracts Reports: 

Emissions Inventory web page at 

http://www.tceq.texas.gov/airquality/airmod/project/pj_report_ei.html. Activity data from the 

RRC specific to 2006 and 2013 were obtained for production of natural gas, crude oil, and 

condensate, along with additional information for parameters such as the total number of 

operational gas wells, operational oil wells, etc. These activity figures were then multiplied by 

appropriate emission factors from the ERG study to obtain oil and gas production emission 

estimates. For example, compressor engine emissions are a function of natural gas production, 

so compressor engine emission rates were multiplied by total natural gas produced. Condensate 

storage tank emission estimates were calculated as a function of condensate production. In a 

similar manner, emissions from crude oil storage tanks are a function of crude oil production. 

The ERG study referenced above contains a summary of how each calculation is performed. The 

2006 oil and gas production emission estimates for the 10-county DFW area are summarized in 

Table 4-1: 2006 DFW Area Oil and Gas Production Emissions by Equipment Type. Emission 

estimates for nitrogen oxides (NOX), volatile organic compounds (VOC), carbon monoxide (CO), 

sulfur dioxide (SO2), and 2.5 micron particulate matter (PM2.5) are provided.

Table 4-1: 2006 DFW Area Oil and Gas Production Emissions by Equipment Type

Oil and Gas Production Equipment NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Natural Gas 4-Cycle Rich Burn Compressors 50 To 499 HP 56.19 0.10 2.54 0.00 0.01

Natural Gas Well Heaters 2.11 0.12 1.77 0.00 0.16

Natural Gas 2-Cycle Lean Burn Compressors 50 To 499 HP 1.45 0.14 0.21 0.00 0.03

Natural Gas 4-Cycle Rich Burn Compressors 500+ HP w/NSCR 0.84 0.16 7.25 0.00 0.05

Natural Gas 4-Cycle Lean Burn Compressors 500+ HP 0.71 1.43 6.77 0.01 0.03

Oil Production - Artificial Lift 0.32 0.00 0.50 0.00 0.00

Oil Production - Heater Treater 0.14 0.01 0.11 0.00 0.01

Natural Gas Well Dehydrators 0.08 1.65 0.23 0.00 0.00

Oil Production - All Processes 0.00 0.01 0.01 0.02 0.00

Natural Gas 4-Cycle Rich Burn Compressors 50 To 499 HP w/NSCR 0.00 0.01 0.61 0.00 0.02

Natural Gas Condensate - Storage Tanks 0.00 18.06 0.00 0.00 0.00

Natural Gas Well Pneumatic Devices 0.00 7.07 0.00 0.00 0.00

Natural Gas Exploration - Well Completion, All Processes 0.00 3.34 0.00 0.00 0.00

Oil and Gas Production - Produced Water 0.00 2.30 0.00 0.00 0.00

Natural Gas Fugitives – Other 0.00 2.04 0.00 0.00 0.00

Natural Gas Fugitives – Valves 0.00 1.73 0.00 0.00 0.00

Natural Gas Well Venting 0.00 1.19 0.00 0.00 0.00

Crude Oil Storage Tanks 0.00 1.18 0.00 0.00 0.00

Natural Gas Condensate - Tank Truck/Railcar Loading 0.00 0.57 0.00 0.00 0.00

Oil Production – Wellhead 0.00 0.55 0.00 0.00 0.00

Oil Well Pneumatic Devices 0.00 0.46 0.00 0.00 0.00

Natural Gas Fugitives – Flanges 0.00 0.28 0.00 0.00 0.00
Oil and Gas Production Equipment NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Natural Gas Fugitives – Connectors 0.00 0.27 0.00 0.00 0.00

Oil Well Completion - All Processes 0.00 0.23 0.00 0.00 0.00

Natural Gas Fugitives - Open Ended Lines 0.00 0.21 0.00 0.00 0.00

Oil Production Fugitives – Other 0.00 0.15 0.00 0.00 0.00

Crude Oil Truck/Railcar Loading 0.00 0.11 0.00 0.00 0.00

Natural Gas Fugitives – Pumps 0.00 0.11 0.00 0.00 0.00

Oil Production Fugitives – Valves 0.00 0.10 0.00 0.00 0.00

Oil Production Fugitives – Pumps 0.00 0.05 0.00 0.00 0.00

Natural Gas Production - Compressor Engines 0.00 0.04 0.06 0.00 0.01

Oil Production Fugitives – Connectors 0.00 0.04 0.00 0.00 0.00

Oil Production Fugitives - Open Ended Lines 0.00 0.01 0.00 0.00 0.00

Natural Gas 2-Cycle Lean Burn Compressors < 50 HP 0.00 0.00 0.01 0.00 0.00

Oil Production Fugitives – Flanges 0.00 0.00 0.00 0.00 0.00

Natural Gas 4-Cycle Rich Burn Compressors <50 HP 0.00 0.00 0.01 0.00 0.00

Oil and Gas Production Total 61.84 43.72 20.09 0.03 0.32

2018 future year emission estimates for oil and gas production were projected using 2013 RRC 

data, which is the latest full year for which such activity information is available. The 2013-to2018 projection factors were obtained from an ERG study entitled Forecasting Oil and Gas 

Activities, which is also available on the TCEQ Air Quality Research and Contracts Reports: 

Emissions Inventory web page. ERG evaluated several methodologies for the purposes of 

projecting oil and gas production levels, and recommended the best one to be the Hubbert peak 

theory, which relies on a bell-shaped curve to predict the rate of fossil fuel extraction over time 

from a specific region. Table 4-2: Barnett Shale Emission Projection Factors from 2013 to 2018

summarizes these projection factors from the ERG study for natural gas, crude oil, and 

condensate. The 2013 emission estimates, based directly on historical RRC data, were then 

multiplied by these factors to obtain the 2018 estimates by equipment type presented in Table 

4-3: 2018 DFW Area Oil and Gas Production Emissions by Equipment Type. Table 4-1 and Table 

4-3 show that compressor engine emissions are the primary source of NOX from oil and gas 

activity in the Barnett Shale, but that the 2018 levels are much lower than 2006. This is 

primarily due to the introduction of rules for compressor engines above 50 horsepower that 

were not in place during 2006. Without these rules, the average natural gas compressor engine 

emission rate would be 6.94 NOX grams/horsepower-hour (gm/hp-hr). Introduction of this rule 

lowered this emission rate by roughly 91% to 0.61 NOX gm/hp-hr.

Table 4-2: Barnett Shale Emission Projection Factors from 2013 to 2018

Fossil Fuel

Type

Barnett Shale Projection

Factor from 2013 to 2018

Natural Gas 47.69%

Crude Oil 52.13%

Condensate 13.67%
Table 4-3: 2018 DFW Area Oil and Gas Production Emissions by Equipment Type

Oil and Gas Production Equipment NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Natural Gas 4-Cycle Rich Burn Compressors 50 To 499 HP 4.68 0.05 1.81 0.00 0.01

Natural Gas 4-Cycle Rich Burn Compressors 50 To 499 HP w/NSCR 1.13 0.05 2.15 0.01 0.09

Natural Gas 4-Cycle Rich Burn Compressors <50 HP 0.69 0.00 0.07 0.00 0.00

Natural Gas 4-Cycle Rich Burn Compressors 500+ HP w/NSCR 0.53 0.02 0.85 0.00 0.04

Oil Production - Artificial Lift 0.15 0.00 0.23 0.00 0.00

Natural Gas 4-Cycle Rich Burn Compressors 500+ HP 0.07 0.00 0.06 0.00 0.00

Natural Gas 4-Cycle Lean Burn Compressors 50 To 499 HP 0.06 0.03 0.14 0.00 0.00

Natural Gas 4-Cycle Lean Burn Compressors <50 HP 0.04 0.00 0.01 0.00 0.00

Natural Gas 2-Cycle Lean Burn Compressors 50 To 499 HP 0.02 0.04 0.07 0.00 0.01

Natural Gas 2-Cycle Lean Burn Compressors 500+ HP 0.02 0.00 0.00 0.00 0.00

Natural Gas Well Dehydrators 0.01 1.62 0.16 0.00 0.00

Natural Gas Well Heaters 0.01 0.00 0.01 0.00 0.00

Natural Gas 4-Cycle Lean Burn Compressors 500+ HP 0.00 0.00 0.02 0.00 0.00

Natural Gas Production - Compressor Engines 0.00 0.01 0.01 0.00 0.00

Oil Production - All Processes 0.00 0.01 0.01 0.02 0.00

Oil Production - Heater Treater 0.00 0.00 0.00 0.00 0.00

Oil and Gas Production - Hydraulic Fracturing Pumps 0.88 0.06 0.19 0.00 0.00

Natural Gas Well Pneumatic Devices 0.00 5.81 0.00 0.00 0.00

Natural Gas Exploration - Well Pneumatic Pumps 0.00 5.57 0.00 0.00 0.00

Natural Gas Condensate - Storage Tanks 0.00 2.87 0.00 0.00 0.00

Natural Gas Fugitives - Other 0.00 2.04 0.00 0.00 0.00

Natural Gas Well Venting 0.00 1.19 0.00 0.00 0.00

Natural Gas Fugitives - Valves 0.00 1.09 0.00 0.00 0.00

Oil and Gas Production - Produced Water 0.00 0.87 0.00 0.00 0.00

Crude Oil Storage Tanks 0.00 0.51 0.00 0.00 0.00

Natural Gas Exploration - Well Completion, All Processes 0.00 0.02 0.00 0.00 0.00

Natural Gas Fugitives - Flanges 0.00 0.28 0.00 0.00 0.00

Natural Gas Fugitives - Connectors 0.00 0.27 0.00 0.00 0.00

Oil Production - Wellhead 0.00 0.26 0.00 0.00 0.00

Natural Gas Fugitives - Open Ended Lines 0.00 0.21 0.00 0.00 0.00

Oil Well Pneumatic Devices 0.00 0.20 0.00 0.00 0.00

Natural Gas Fugitives - Pumps 0.00 0.11 0.00 0.00 0.00

Natural Gas Condensate - Tank Truck/Railcar Loading 0.00 0.09 0.00 0.00 0.00

Oil Production Fugitives - Other 0.00 0.07 0.00 0.00 0.00

Oil Well Completion - All Processes 0.00 0.06 0.00 0.00 0.00

Oil Exploration - Mud Degassing 0.00 0.02 0.00 0.00 0.00

Oil Well Pneumatic Pumps 0.00 0.06 0.00 0.00 0.00

Crude Oil Truck/Railcar Loading 0.00 0.05 0.00 0.00 0.00

Oil Production Fugitives - Valves 0.00 0.05 0.00 0.00 0.00

Oil Production Fugitives - Pumps 0.00 0.03 0.00 0.00 0.00

Oil Production Fugitives - Connectors 0.00 0.02 0.00 0.00 0.00

Natural Gas Exploration - Mud Degassing 0.00 0.60 0.00 0.00 0.00

Oil Production Fugitives - Open Ended Lines 0.00 0.00 0.00 0.00 0.00
Oil and Gas Production Equipment NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Oil Production Fugitives - Flanges 0.00 0.00 0.00 0.00 0.00

Oil and Gas Production Total 8.31 24.24 5.80 0.03 0.15

The 2006 and 2018 oil and gas production emissions presented in Table 4-3 do not include 

those from large point sources that are required to report emissions directly to the TCEQ. Table 

4-4: 2006 DFW Area Point Source Oil and Gas Emission by Industry Type and Table 4-5: 2018 

DFW Area Point Source Oil and Gas Emissions by Industry Type present respective 2006 and 

2018 summaries of the point source emission estimates by industry type associated with oil and 

gas production. Additional detail on point source emissions inventory development and 

processing can be found in Chapter 2 of this Appendix.

Table 4-4: 2006 DFW Area Point Source Oil and Gas Emission by Industry Type

Standard Industrial

Classification (SIC) Description

SIC

Code

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Crude Petroleum and Natural Gas 1311 4.78 15.67 4.88 0.00 0.20

Natural Gas Liquids 1321 5.43 2.70 2.58 0.01 0.17

Natural Gas Transmission 4922 1.03 0.81 0.96 0.00 0.04

Petroleum Bulk Stations and Terminals 5171 0.08 1.89 0.12 0.00 0.00

Mixed, Manufactured, LPG Production 4925 0.21 0.00 0.19 0.04 0.01

Refined Petroleum Pipelines 4613 0.01 0.74 0.02 0.00 0.00

DFW Area Total NA 11.53 21.82 8.74 0.05 0.42

Table 4-5: 2018 DFW Area Point Source Oil and Gas Emissions by Industry Type

Standard Industrial

Classification (SIC) Description

SIC

Code

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Crude Petroleum and Natural Gas 1311 10.74 16.70 8.44 0.03 0.67

Natural Gas Liquids 1321 4.48 5.01 3.24 0.01 0.20

Natural Gas Transmission 4922 1.06 2.29 0.79 0.01 0.19

Petroleum Bulk Stations and Terminals 5171 0.06 1.66 0.15 0.00 0.00

Mixed, Manufactured, LPG Production 4925 0.02 0.00 0.11 0.01 0.01

Refined Petroleum Pipelines 4613 0.01 0.37 0.02 0.00 0.00

DFW Area Total NA 16.37 26.02 12.75 0.07 1.07

Daily average drilling rig emission estimates for 2006 and 2018 are summarized in Table 4-6: 

2006 and 2018 DFW Area Drilling Rig Emission Estimates. The 2006 estimates were based on 

an ERG study entitled Development of Texas Statewide Drilling Rigs Emission Inventories, 

which is available on the TCEQ Air Quality Research and Contracts Reports: Emissions 

Inventory web page. 

Table 4-6: 2006 and 2018 DFW Area Drilling Rig Emission Estimates

Calendar Year for Drilling Rig Activity NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

2006 Drilling Rig Emissions 18.23 1.16 3.57 1.65 0.59

2018 Drilling Rig Emissions 2.82 0.21 0.45 0.00 0.06
The 2018 drilling rig emission estimates were obtained by applying 2018 emission factors to the 

2013 drilling activity summarized in Table 4-7: 2013 DFW Area Oil and Gas Drilling Activity. 

Different emission rates apply based on average well depth and whether conventional “vertical 

only” drilling is being done versus the horizontal drilling commonly associated with fracturing. 

Since drilling rig equipment is subject to federal non-road emission standards, average emission 

rates decline over time due to fleet turnover. Drilling rig emission rates for each year from 1999-

2040 are summarized in Chapter 4: Emissions Inventory Development and Results of the 

Development of Texas Statewide Drilling Rigs Emission Inventories ERG study.

Table 4-7: 2013 DFW Area Oil and Gas Drilling Activity

Type and Depth of

2013 Drilling Levels

2013 Feet

Drilled

Vertical/Horizontal Drilling 5,556,499

Vertical Drilling less than 7,000 Feet 17,608

Vertical Drilling greater than 7,000 Feet 16,073

Figure 4-1: Barnett Shale Drilling and Natural Gas Production from 1993-2014 summarizes 

Barnett Shale drilling and production levels from 1993 through the present based on regularly 

updated information available on the RRC Barnett Shale Information web page. The blue line in 

Figure 4-1 is the daily average natural gas production rate from 1993 through 2014. As shown, 

Barnett Shale natural gas production has followed a bell-shaped curve with production levels 

peaking in 2012 when the daily average extraction rate was 5,743 million cubic feet (MMcf) per 

day. From this 2012 peak, the 2013 daily average was 5,355 MMcf/day (7% lower) and the 

current 2014 daily average was 4,877 MMcf/day (15% lower).

The black line in Figure 4-1 is the Henry Hub natural gas spot price, which hovered in the $7-9 

range during the Barnett Shale drilling boom years of 2005 through 2008, and then dropped to 

the $3-4 range where it has remained since. The red line in Figure 4-1 shows how the number of 

drilling permits issued reached a peak of roughly 4,000 in 2008, declined steeply through 2009 

as natural gas prices fell, and since 2012 have been in the range of roughly 1,000 per year, 

similar to the pre-drilling boom years of 2001-2004. A University of Texas at Austin study 

entitled Barnett Study Determines Full-Field Reserves, Production Forecast evaluated 

historical production data per well to determine that the natural gas extraction rate is highest in 

the first year and then begins to decline exponentially. For an average production span of 25 

years per well, roughly 50% of the natural gas is extracted in the first five years, with the 

remaining 50% extracted within the subsequent twenty years. The decline in natural gas 

production since 2012 is expected because wells that began producing during the drilling boom 

years of 2005 through 2008 are now past this five-year mark, and drilling levels from 2009 

onwards have not been sufficient to keep production either at or near the 2012 peak. The TCEQ 

will continue to monitor the monthly updates provided by the RRC to determine if any changes 

occur in these recent drilling and production trends.
Figure 4-1: Barnett Shale Drilling and Natural Gas Production from 1993-2014

The production and drilling rig emission estimates presented above were prepared for 

photochemical model input using version 3 of the Emissions Processor System (EPS3). Spatial 

allocation of these emission estimates was based on the latest available activity data from the 

RRC. For example, 2013 natural gas production data for each operational well were used to 

develop a weighted surrogate for allocating 2018 natural gas production emissions. A similar 

approach was used to develop separate weighted surrogates for emissions associated with crude 

oil and condensate production. 2018 drilling rig emissions were allocated to locations where 

2013 wells were drilled. Even though it is unlikely that 2018 drilling will occur in the exact same 

locations as 2013, low-level emissions are evenly distributed within 4 kilometer (km) grid cells 

for photochemical model input. Since 2018 production and drilling is likely to be concentrated 

near currently operational wells, this spatial allocation approach is reasonable. 2006 production 

and drilling rig emissions were allocated based on available RRC data specific to that year.

For the non-DFW areas of Texas, all of the steps described above are similar for the 

development and EPS3 processing of emissions associated with drilling rigs and production of 

natural gas, crude oil, and condensate. For projecting to 2018, the latest available RRC activity 

data from 2013 were obtained for every Texas county. The ERG Forecasting Oil and Gas 

Activities study provided different projection factors for the Barnett, Eagle Ford, and 

Haynesville Shale formations. The EPS3 processing streams for emissions from oil and gas 

activities are divided into seven separate streams for:

$0.00

$1.00

$2.00

$3.00

$4.00

$5.00

$6.00

$7.00

$8.00

$9.00

$10.00

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

9,000

10,000

Henry Hub Spot Price (Dollars per Million BTU)

Well Counts, Drilling Permits Issued, and Daily Average Production (MMCF)

Calendar Year

Well Count Divided by Two - Through 2014

Drilling Permits Issued - Through 2014

Daily Average Production - Through 2014

Henry Hub Spot Price - Annual Average
• the 10-county DFW area;

• the eight Barnett Shale counties of Cooke, Erath, Hill, Hood, Jack, Montague, Palo Pinto, 

and Somervell not included within the 10-county DFW area;

• the eight counties in the Houston-Galveston-Brazoria (HGB) area;

• the 10 counties comprising the Texas portion of the Haynesville Shale;

• 26 counties within the Eagle Ford Shale in South Texas;

• 45 counties within the Permian Basin in West Texas; and

• the remaining 147 Texas counties.

The complete EPS3 processing streams for all of these areas are available for both 2006 and 

2018 at ftp://amdaftp.tceq.texas.gov/pub/Oil_Gas_EI/2006/ and 

ftp://amdaftp.tceq.texas.gov/pub/Oil_Gas_EI/2018/. The following pages contain graphical 

plots of the 2006 and 2018 oil and gas production and drilling NOX and VOC emissions for the 

DFW area. As shown, these emissions are concentrated in the western portion of the DFW area 

where oil and gas production occurs. These plots are respectively entitled Figure 4-2: 2006 DFW 

Oil and Gas Production NOX Emissions Distribution, Figure 4-3: 2006 DFW Oil and Gas 

Production VOC Emissions Distribution, Figure 4-4: 2018 DFW Oil and Gas Production NOX

Emissions Distribution, and Figure 4-5: 2018 DFW Oil and Gas Production VOC Emissions 

Distribution. Spatial allocation of drilling rig emission estimates for 2006 and 2018, 

respectively, are provided in Figure 4-6: 2006 DFW Drilling Rig NOX Emissions Distribution

and Figure 4-7: 2018 DFW Drilling Rig NOX Emissions Distribution. Since diesel-powered 

drilling rig equipment emits low levels of VOC, only NOX plots are provided here. As shown, 

drilling rig emissions are also concentrated in the western half of DFW where oil and gas activity 

occurs.

For the non-Texas U.S. areas of the modeling domain, oil and gas production and drilling rig 

emission estimates from the EPA National Emissions Inventory (NEI) were used. The 2008 NEI

was used for the 2006 inputs, and the 2011 NEI was used for the 2018 inputs. The emission 

estimates from these NEI datasets were processed through EPS3 in a manner similar to that 

described above for Texas.
Figure 4-2: 2006 DFW Oil and Gas Production NOX Emissions Distribution
Figure 4-3: 2006 DFW Oil and Gas Production VOC Emissions Distribution
Figure 4-4: 2018 DFW Oil and Gas Production NOX Emissions Distribution
Figure 4-5: 2018 DFW Oil and Gas Production VOC Emissions Distribution
Figure 4-6: 2006 DFW Drilling Rig NOX Emissions Distribution
Figure 4-7: 2018 DFW Drilling Rig NOX Emissions Distribution
4.2 Airports

The TCEQ contracted with the North Central Texas Council of Governments (NCTCOG) to 

develop DFW area airport emission inventories for several years from 1996 through 2029. The 

report and associated electronic files are available on the TCEQ DFW airport emissions FTP site

at ftp://amdaftp.tceq.texas.gov/pub/Offroad_EI/Airports/DFW/. Emission estimates were 

prepared for DFW International, Love Field, and 59 regional airports. The 2006 base case and 

2018 future year inventories were not developed under this study, but estimates were obtained 

by interpolating the results between 2002 and 2008 for 2006, and between 2017 and 2020 for 

2018. An Excel spreadsheet available on the TCEQ DFW airport emissions FTP site summarizes 

this interpolation work. A separate study to update Love Field emission estimates was funded by 

the City of Dallas Aviation Department and contracted to the consulting firm Leigh Fisher. This 

study and associated electronic files are also available on the TCEQ DFW airport emissions FTP 

site. Love Field emission estimates were prepared directly by Leigh Fisher for both the 2006 and 

2018 years.

At the time both the NCTCOG and Leigh Fisher work was performed, the latest version of the 

Emissions Dispersion and Modeling System (EDMS) from the Federal Aviation Administration

(FAA) was used. For past years, historical flight activity for each airport is input to the EDMS 

model. Future year flight activity projections are based on Terminal Area Forecast (TAF)

datasets available from FAA. In addition to estimating emissions from aircraft activity, the 

EDMS model outputs estimates for auxiliary power units (APUs) and ground support 

equipment (GSE) at major airports. 2006 summaries of aircraft, APU, and GSE emission 

estimates for DFW International, Love Field, and the 59 smaller regional airports throughout 

DFW are presented in Table 4-8: 2006 DFW International Airport Emissions by Source Type, 

Table 4-9: 2006 Love Field Airport Emissions by Source Type, and Table 4-10: 2006 DFW Area 

Regional Airport Emissions by Source Type, respectively. The EDMS model estimates emissions 

associated with parking garage activity and routine construction at major airports, but these are 

already included in the comprehensive TCEQ on-road and non-road construction emission 

inventories. 2006 emission totals for DFW International, Love Field, and the 59 smaller 

regional airports are presented in 

Table 4-11: 2006 DFW Area Major and Regional Airport Emissions.

Table 4-8: 2006 DFW International Airport Emissions by Source Type

DFW International Airport

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 8.73 2.05 8.07 0.97 0.18

Auxiliary Power Units 0.10 0.01 0.20 0.02 0.02

Ground Support Equipment 1.01 0.30 8.42 0.05 0.03

DFW International Airport Total 9.84 2.37 16.69 1.04 0.23

Table 4-9: 2006 Love Field Airport Emissions by Source Type

Love Field Airport

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 1.12 0.55 3.06 0.14 0.03

Auxiliary Power Units 0.03 0.01 0.12 0.01 0.01

Ground Support Equipment 0.07 0.01 0.21 0.01 0.00

Love Field Airport Total 1.22 0.57 3.39 0.16 0.04
Table 4-10: 2006 DFW Area Regional Airport Emissions by Source Type

59 Regional Airports

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 0.89 1.32 22.60 0.19 0.02

Auxiliary Power Units 0.09 0.01 0.21 0.01 0.01

Ground Support Equipment 0.75 0.20 5.20 0.04 0.02

59 Regional Airports Total 1.72 1.52 28.01 0.24 0.06

Table 4-11: 2006 DFW Area Major and Regional Airport Emissions

DFW Area Airport or

Airport Group

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

DFW International 9.84 2.37 16.69 1.04 0.23

Love Field 1.22 0.57 3.39 0.16 0.04

59 Regional Airports 1.72 1.52 28.01 0.24 0.06

DFW Area Total for 61 Airports 12.78 4.46 48.09 1.44 0.33

2018 summaries of aircraft, APU, and GSE emission estimates for DFW International are shown 

in Table 4-12: 2018 DFW International Airport Emissions by Source Type, Table 4-13: 2018 

Love Field Airport Emissions by Source Type, and Table 4-14: 2018 DFW Area Regional Airport 

Emissions by Source Type, respectively. 2018 emission totals for DFW International, Love Field, 

and the 59 smaller regional airports are presented in Table 4-15: 2018 DFW Area Major and 

Regional Airport Emissions.

Table 4-12: 2018 DFW International Airport Emissions by Source Type

DFW International Airport

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 10.31 1.96 9.12 1.14 0.18

Auxiliary Power Units 0.02 0.00 0.03 0.00 0.00

Ground Support Equipment 0.18 0.06 1.50 0.01 0.01

DFW International Airport Total 10.50 2.02 10.65 1.15 0.19

Table 4-13: 2018 Love Field Airport Emissions by Source Type

Love Field Airport

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 1.62 0.41 2.03 0.17 0.03

Auxiliary Power Units 0.03 0.00 0.06 0.00 0.00

Ground Support Equipment 0.05 0.01 0.34 0.00 0.00

Love Field Airport Total 1.70 0.42 2.43 0.18 0.03

Table 4-14: 2018 DFW Area Regional Airport Emissions by Source Type

59 Regional Airports

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Aircraft Operation 0.69 1.07 20.01 0.15 0.02

Auxiliary Power Units 0.06 0.00 0.15 0.01 0.01

Ground Support Equipment 0.12 0.03 0.83 0.00 0.01
59 Regional Airports

Source Category

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

59 Regional Airports Total 0.86 1.10 20.99 0.16 0.03

Table 4-15: 2018 DFW Area Major and Regional Airport Emissions

DFW Area Airport or

Airport Group

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

DFW International 10.50 2.02 10.65 1.15 0.19

Love Field 1.70 0.43 2.43 0.18 0.03

59 Regional Airports 0.86 1.10 20.99 0.16 0.03

DFW Area Total for 61 Airports 13.06 3.55 34.07 1.49 0.25

The airport emissions were prepared for photochemical modeling input using EPS3. The 

emissions were allocated to grid cells using spatial surrogates based on the respective areal 

extent of each airport location. For the non-DFW areas of Texas, 2011 airport emission estimates 

from the Texas Air Emissions Repository System (TexAER) were backcast to 2006 and projected 

to 2018. The EPS3 processing for Texas airport emissions is divided into streams for:

• the 10-county DFW area;

• the eight-county HGB area; and

• the remaining 236 Texas counties.

The complete EPS3 processing streams for these areas are available for 2006 and 2018 at 

ftp://amdaftp.tceq.texas.gov/pub/Offroad_EI/Airports/2006/ and 

ftp://amdaftp.tceq.texas.gov/pub/Offroad_EI/Airports/2018/. The following pages contain 

graphical plots of the 2006 and 2018 airport NOX emissions for the DFW area. These plots are 

respectively entitled Figure 4-8: 2006 DFW Airport NOX Emissions Distribution and Figure 4-9: 

2018 DFW Airport NOX Emissions Distribution. Since airports are not significant contributors 

of VOC emissions, only NOX plots are provided here.

For the non-Texas U.S. areas of the modeling domain, airport emission estimates from the EPA 

NEI were used. The 2008 NEI was used for the 2006 inputs, and the 2011 NEI was used for the 

2018 inputs. The airport source emission estimates from these NEI datasets were processed 

through EPS3 in a manner similar to that described above for the airport source emissions 

within Texas.
Figure 4-8: 2006 DFW Airport NOX Emissions Distribution
Figure 4-9: 2018 DFW Airport NOX Emissions Distribution
4.3 Locomotives

Locomotive emission estimates were developed for the 2011 calendar year and are included 

within TexAER at http://www5.tceq.state.tx.us/texaer/index.cfm. A summary of the line-haul 

and rail-yard switcher categories is provided in Table 4-16: 2011 DFW Area Line-Haul and 

Switcher Locomotive Emissions. Ammonia (NH3) emission estimates were available in this 

dataset and are included in the locomotive emissions summaries provided below.

Table 4-16: 2011 DFW Area Line-Haul and Switcher Locomotive Emissions

Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Class I 16.67 0.91 3.02 0.18 0.01 0.48

Line-Haul Locomotives – Classes II and III 0.57 0.02 0.06 0.00 0.00 0.01

Rail-Yard Switcher Locomotives 7.02 0.44 0.79 0.05 0.00 0.18

DFW Area Total 24.26 1.37 3.87 0.24 0.01 0.66

The locomotive emissions data output from TexAER were prepared for photochemical modeling 

using EPS3. Table 4-17: EPS3 Modules for Processing Locomotive Emissions summarizes the 

steps that were taken to process the 2006 and 2018 locomotive inventories.

Table 4-17: EPS3 Modules for Processing Locomotive Emissions

EPS3

Module Description

PREAM Convert text-based input files to binary format for further processing.

LBASE Assign line-haul emissions to known railway segments (not for switchers).

CNTLEM Apply activity, emission rate, and temperature/humidity NOX correction.

TMPRL Apply profiles to temporally allocate daily emission totals.

SPCEMS Chemically speciate VOC emissions into olefins, paraffins, etc.

GRDEM Spatially allocate switcher emissions with surrogates.

MRGUAM Merge and adjust multiple gridded files for photochemical model input.

The 2011 locomotive emission estimates were backcast to 2006 and forecast to 2018 with the 

EPS3 CNTLEM module based on changes in both emission rates and activity levels. Fleet 

average emission factors from 2006 through 2040 for NOX, VOC, and PM were obtained from 

an April 2009 EPA document entitled Emission Factors for Locomotives, EPA-420-F-09-025,

which accounts for fleet turnover effects from locomotive engines as new ones entering the fleet 

must comply with more stringent standards. The changes in SO2 emission rates were obtained 

from an April 2009 EPA document entitled Suggested Nationwide Average Fuel Properties, 

EPA-420-B-09-018, which accounts for required changes in diesel fuel sulfur levels. The relative 

changes in these emission rates by locomotive category from both 2011-to-2006, and 2011-to2018 are summarized in Table 4-18: 2011-to-2006 Locomotive Emission Rate Adjustment 

Factors and Table 4-19: 2011-to-2018 Locomotive Emission Rate Adjustment Factors, 

respectively. A value of 100% indicates no change, while values lower than 100% indicate a 

reduction in emissions, and values above 100% indicate an emissions increase.
Table 4-18: 2011-to-2006 Locomotive Emission Rate Adjustment Factors

Locomotive Category

Description

NOX

Change

VOC

Change

SO2

Change

PM

Change

Large Line-Haul 120.81% 123.38% 7006.25% 145.45%

Large Switchers 106.38% 107.14% 7006.25% 122.64%

Small Railroads 100.00% 100.00% 7006.25% 114.04%

Passenger/Commuter 146.11% 119.75% 7006.25% 144.44%

Overall Average 119.75% 121.95% 7006.25% 142.22%

Table 4-19: 2011-to-2018 Locomotive Emission Rate Adjustment Factors

Locomotive Category

Description

NOX

Change

VOC

Change

SO2

Change

PM

Change

Large Line-Haul 72.48% 54.55% 34.38% 61.36%

Large Switchers 85.96% 82.14% 34.38% 83.02%

Small Railroads 97.52% 100.00% 34.38% 94.74%

Passenger/Commuter 62.87% 50.62% 34.38% 57.78%

Overall Average 74.52% 58.54% 34.38% 62.22%

The activity levels were backcast to 2006 with the EPS3 CNTLEM module based on a U.S. 

Energy Information Administration (EIA) table entitled Transportation Sector Key Indicators 

and Delivered Energy Consumption. These annual tables provide historical estimates of 

locomotive activity. Future activity was held constant at 2011 levels. The 2006 and 2018 activity 

adjustments relative to 2011 are shown in Table 4-20: 2006 and 2018 Locomotive Activity 

Adjustments Relative to 2011.

Table 4-20: 2006 and 2018 Locomotive Activity Adjustments Relative to 2011

Activity Change

Description Change

Activity Change from 2011 to 2006 106.36%

Activity Change from 2011 to 2018 100.00%

Application of these emission factor and activity adjustments resulted in the 2006 and 2018 

locomotive emission estimates summarized in Table 4-21: 2006 DFW Area Line-Haul and 

Switcher Locomotive Emissions and Table 4-22: 2018 DFW Area Line-Haul and Switcher 

Locomotive Emissions, respectively.

Table 4-21: 2006 DFW Area Line-Haul and Switcher Locomotive Emissions

Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Class I 21.42 1.19 3.22 13.41 0.01 0.74

Line-Haul Locomotives – Classes II and III 0.60 0.02 0.06 0.29 0.00 0.02

Rail-Yard Switcher Locomotives 7.95 0.51 0.84 3.86 0.00 0.23

DFW Area Total 29.97 1.72 4.12 17.57 0.01 0.98
Table 4-22: 2018 DFW Area Line-Haul and Switcher Locomotive Emissions

Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Class I 12.09 0.50 3.02 0.06 0.01 0.29

Line-Haul Locomotives – Classes II and III 0.55 0.02 0.06 0.00 0.00 0.01

Rail-Yard Switcher Locomotives 6.04 0.37 0.79 0.02 0.00 0.15

DFW Area Total 18.68 0.88 3.87 0.08 0.01 0.45

The 24-hour locomotive emission totals reported in TexAER do not account for the effects of 

hourly variation in temperature and humidity on NOX emissions. Greater detail on the 

development of correction equations to account for these effects can be found in Appendices 

F.4: Humidity and Temperature Correction Factors for NOX Emissions from Diesel Engines and 

F.5: Humidity and Temperature Correction Factors for NOX Emissions from Spark Ignited 

Engines of the December 2004 HGB SIP revision. During EPS3 processing, the CNTLEM 

module is also used to apply an hourly temperature/humidity NOX correction and the impacts 

on the 2006 and 2018 locomotive DFW inventories are presented in Table 4-23:

Temperature/Humidity NOX Correction for Locomotive Emissions.

Table 4-23: Temperature/Humidity NOX Correction for Locomotive Emissions

Locomotive Source

Classification Description

2006 NOX

Change (tpd)

2018 NOX

Change (tpd)

Line-Haul Locomotives – Class I -0.94 -0.53

Line-Haul Locomotives – Classes II and III -0.03 -0.03

Rail-Yard Switcher Locomotives -0.34 -0.26

DFW Area Total -1.31 -0.81

The activity level for locomotive activity does not vary much by day type, so there are negligible 

differences in weekday versus weekend emissions for this source category. The line-haul 

emissions were spatially allocated to individual railway segments based on gross ton miles 

(GTM) activity data. The switcher emissions were allocated to known rail yards within the DFW 

area. Table 4-24: 2006 DFW Adjusted Locomotive Emissions and Table 4-25: 2018 DFW Area 

Adjusted Locomotive Emissions present the 2006 and 2018 DFW area locomotive emission 

inputs for the photochemical model for each episode day in these respective years.

Table 4-24: 2006 DFW Adjusted Locomotive Emissions

Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Class I 20.48 1.19 3.22 13.41 0.01 0.74

Line-Haul Locomotives – Classes II and III 0.58 0.02 0.06 0.29 0.00 0.02

Rail-Yard Switcher Locomotives 7.61 0.51 0.84 3.86 0.00 0.23

DFW Area Total 28.67 1.72 4.12 17.57 0.01 0.98

Table 4-25: 2018 DFW Area Adjusted Locomotive Emissions

Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Class I 11.55 0.50 3.02 0.06 0.01 0.29
Locomotive Source

Classification Description

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Line-Haul Locomotives – Classes II and III 0.53 0.02 0.06 0.00 0.00 0.01

Rail-Yard Switcher Locomotives 5.78 0.37 0.79 0.02 0.00 0.15

DFW Area Total 17.86 0.88 3.87 0.08 0.01 0.45

For the non-DFW areas of Texas, all of the steps described above are similar for the TexAER

extraction and EPS3 processing of locomotive emission estimates for 2006 and 2018. The EPS3 

processing for Texas non-road emissions is divided into streams for:

• the 10-county DFW area;

• the eight-county HGB area; and

• the remaining 236 Texas counties.

The complete EPS3 processing streams for all of these areas are available for both 2006 and 

2018 at ftp://amdaftp.tceq.texas.gov/pub/Offroad_EI/Locomotives/2006/ and 

ftp://amdaftp.tceq.texas.gov/pub/Offroad_EI/Locomotives/2018/. The following pages contain 

graphical plots of the 2006 and 2018 locomotive NOX emissions for the DFW area. These plots 

are respectively entitled Figure 4-10: 2006 DFW Locomotive NOX Emissions Distribution and 

Figure 4-11: 2018 DFW Locomotive NOX Emissions Distribution. Since the diesel engines that 

power locomotives are not significant contributors of VOC emissions, only NOX plots are 

provided here.

For the non-Texas U.S. areas of the modeling domain, locomotive emission estimates from the 

EPA NEI were used. The 2008 NEI was used for the 2006 inputs, and the 2011 NEI was used for 

the 2018 inputs. The locomotive emission estimates from these NEI datasets were processed 

through EPS3 in a manner similar to that described above for the locomotive emissions within 

Texas.
Figure 4-10: 2006 DFW Locomotive NOX Emissions Distribution
Figure 4-11: 2018 DFW Locomotive NOX Emissions Distribution
4.4 Non-Road/TexN

Non-road emissions for 2006 and 2018 for the 10-county DFW area were estimated with a 

customized version of EPA’s NONROAD model called Texas NONROAD (TexN). The full EPA 

web page address is http://www.epa.gov/otaq/nonrdmdl.htm and the full TCEQ TexN FTP site 

address is ftp://amdaftp.tceq.texas.gov/pub/Nonroad_EI/TexN/. For each county specified in a 

TexN scenario, 25 separate runs of the NONROAD model are performed for the following nonroad categories outlined in Table 4-26: Texas NONROAD Model Subsector Categories. Runs 1 

through 25 (excluding 24) are for specific diesel construction equipment (DCE) categories, while 

the numeric code of 0 is for all non-DCE categories.

Table 4-26: Texas NONROAD Model Subsector Categories

Numeric

Code

NONROAD Model Subsector Description

(Diesel Construction Equipment for 1-24)

0 Other - Non-Diesel Construction Equipment

1 DCE - Agricultural Activities

2 DCE - Boring and Drilling Equipment

3 DCE - Brick and Stone Operations

4 DCE - City and County Road Construction

5 DCE - Commercial Construction

6 DCE - Concrete Operations

7 DCE - County-Owned Construction Equipment

8 DCE – Cranes

9 DCE - Heavy Highway Construction

10 DCE - Landfill Operations

11 DCE - Landscaping Activities

12 DCE - Manufacturing Operations

13 DCE - Municipal-Owned Construction Equipment

14 DCE - Transportation/Sales/Services

15 DCE - Residential Construction

16 DCE - Rough Terrain Forklifts

17 DCE - Scrap/Recycling Operations

18 DCE - Skid Steer Loaders

19 DCE - Special Trades Construction

20 DCE - Trenchers

21 DCE - TxDOT Construction Equipment

22 DCE - Utility Construction

23 DCE - Mining and Quarry Operation

25 DCE - Off-Road Tractors, Miscellaneous, and Equipment Under 25 Horsepower

2006 and 2018 summer weekday scenarios were run with the TexN model for all 10 counties in 

the DFW area. 25 DCE subcategories for each of the 10 counties resulted in a total of 250 

NONROAD model runs for each calendar year. The results of this work are available on the 

TCEQ non-road emissions FTP site at ftp://amdaftp.tceq.texas.gov/pub/Nonroad_EI/TEX/. 

The NOX, VOC, CO, SO2, and PM2.5 emissions by county along with associated non-road 

equipment population figures are presented for 2006 and 2018, respectively, in Table 4-27: 
2006 DFW Area Non-Road Emissions Inventory by County and Table 4-28: 2018 DFW Area 

Non-Road Emissions Inventory by County.

Table 4-27: 2006 DFW Area Non-Road Emissions Inventory by County

DFW Area

County

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Collin 211,540 11.20 7.58 88.28 1.29 1.05

Dallas 837,764 38.24 27.70 377.72 3.54 3.19

Denton 170,720 7.09 5.52 58.22 0.79 0.66

Ellis 43,816 4.82 1.99 20.75 0.46 0.34

Johnson 41,276 4.36 1.23 15.07 0.57 0.38

Kaufman 28,960 4.62 1.39 14.69 0.61 0.40

Parker 33,844 3.62 1.34 11.40 0.52 0.33

Rockwall 24,266 1.20 1.48 10.30 0.15 0.13

Tarrant 525,720 23.29 15.19 200.87 2.12 1.81

Wise 23,033 4.86 1.32 9.32 0.74 0.40

DFW Total 1,940,938 103.30 64.73 806.60 10.78 8.69

Table 4-28: 2018 DFW Area Non-Road Emissions Inventory by County

DFW Area

County

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Collin 266,332 5.88 4.15 64.77 0.01 0.56

Dallas 1,052,829 17.68 14.20 276.27 0.05 1.73

Denton 212,537 3.62 2.82 42.46 0.01 0.31

Ellis 55,015 1.87 1.00 12.48 0.00 0.15

Johnson 51,236 1.64 0.60 9.25 0.00 0.14

Kaufman 35,781 1.57 0.73 9.37 0.00 0.14

Parker 42,717 1.25 0.76 8.38 0.00 0.11

Rockwall 29,298 0.62 0.74 7.82 0.00 0.07

Tarrant 656,192 9.88 7.44 141.99 0.03 0.92

Wise 27,991 1.13 0.61 5.78 0.00 0.09

DFW Total 2,429,928 45.15 33.04 578.58 0.12 4.22

Even with overall growth in the non-road equipment population from roughly 1.9 million in 

2006 to 2.4 million in 2018, total emissions decrease due to the more stringent emissions 

standards for new equipment purchases, combined with the simultaneous attrition of older, 

higher-emitting pieces of non-road equipment. The 10-county DFW non-road emissions 

inventory includes 193 different types of equipment referenced by source classification code 

(SCC). The files available on the TCEQ non-road emissions FTP site include a complete set of 

estimates by county and SCC. The 10-county DFW aggregate equipment categories for 2006 and 

2018, respectively, are summarized in Table 4-29: 2006 DFW Area Non-Road Emissions 

Inventory by Equipment Group and Table 4-30: 2018 DFW Area Non-Road Emissions 

Inventory by Equipment Group.
Table 4-29: 2006 DFW Area Non-Road Emissions Inventory by Equipment Group

Equipment

Category

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Agricultural Equipment 9,117 12.74 1.43 20.31 1.74 1.10

Commercial Equipment 207,441 8.60 14.08 291.64 0.68 0.77

Construction and Mining Equipment 84,012 47.44 8.50 75.99 6.59 4.66

Industrial Equipment 46,923 31.33 8.01 123.01 1.61 1.09

Lawn and Garden Equipment 1,509,143 2.64 22.26 256.99 0.14 0.83

Pleasure Craft 37,985 0.27 4.50 12.21 0.01 0.06

Railroad Equipment 101 0.08 0.02 0.07 0.01 0.01

Recreational Equipment 46,216 0.20 5.93 26.39 0.01 0.16

DFW Total 1,940,938 103.30 64.73 806.60 10.78 8.69

Table 4-30: 2018 DFW Area Non-Road Emissions Inventory by Equipment Group

Equipment

Category

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Agricultural Equipment 11,286 4.95 0.64 5.24 0.01 0.33

Commercial Equipment 281,479 5.91 7.65 250.59 0.02 0.55

Construction and Mining Equipment 107,975 21.38 4.56 48.97 0.03 1.94

Industrial Equipment 59,642 10.65 1.50 30.29 0.04 0.32

Lawn and Garden Equipment 1,860,832 1.73 12.76 203.95 0.01 0.94

Pleasure Craft 41,419 0.31 1.99 9.57 0.00 0.02

Railroad Equipment 137 0.06 0.01 0.04 0.00 0.01

Recreational Equipment 67,158 0.17 3.94 29.93 0.00 0.10

DFW Total 2,429,928 45.15 33.04 578.58 0.12 4.22

The 10-county DFW non-road emissions are summarized by fuel type for 2006 and 2018, 

respectively, in Table 4-31: 2006 DFW Area Non-Road Emissions Inventory by Fuel Type and 

Table 4-32: 2018 DFW Area Non-Road Emissions Inventory by Fuel Type.

Table 4-31: 2006 DFW Area Non-Road Emissions Inventory by Fuel Type

Equipment

Category

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Two-Stroke Gasoline 593,205 0.25 20.05 50.50 0.00 1.13

Four-Stroke Gasoline 1,201,542 4.66 29.93 601.14 0.03 0.19

Diesel 119,469 75.33 7.90 38.34 10.72 7.23

Compressed Natural Gas (CNG) 1,998 1.78 1.05 13.76 0.00 0.02

Liquefied Petroleum Gas (LPG) 24,723 21.28 5.81 102.85 0.03 0.13

DFW Total 1,940,938 103.30 64.73 806.60 10.78 8.69

Table 4-32: 2018 DFW Area Non-Road Emissions Inventory by Fuel Type

Equipment

Category

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Two-Stroke Gasoline 730,319 0.35 13.23 53.80 0.00 1.19
Equipment

Category

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Four-Stroke Gasoline 1,499,476 2.24 14.49 476.30 0.03 0.23

Diesel 164,059 37.21 4.11 17.97 0.05 2.62

Compressed Natural Gas (CNG) 2,437 0.32 0.09 1.53 0.00 0.01

Liquefied Petroleum Gas (LPG) 33,637 5.03 1.12 28.98 0.03 0.17

DFW Total 2,429,928 45.15 33.04 578.58 0.12 4.22

The 10-county DFW non-road emissions for 2006 and 2018, respectively, are summarized by 

the 25 DCE subcategory codes from Table 4-26 in Table 4-33: 2006 DFW Area Non-Road 

Emissions Inventory by Diesel Subcategory and Table 4-34: 2018 DFW Area Non-Road 

Emissions Inventory by Diesel Subcategory.

Table 4-33: 2006 DFW Area Non-Road Emissions Inventory by Diesel Subcategory

Non-Road

DCE Subsector

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Non-Diesel Equipment 1,883,489 56.51 59.80 781.90 4.20 4.22

Agricultural Activities 895 1.31 0.14 0.71 0.20 0.13

Boring and Drilling Equipment 107 0.11 0.01 0.04 0.01 0.01

Brick and Stone Operations 206 0.68 0.05 0.27 0.11 0.05

City and County Road Construction 1,559 0.37 0.03 0.15 0.04 0.03

Commercial Construction 13,373 3.58 0.34 1.58 0.39 0.26

Concrete Operations 201 0.52 0.04 0.23 0.08 0.04

County-Owned Construction 283 0.23 0.02 0.11 0.03 0.02

Cranes 996 2.33 0.16 0.58 0.29 0.13

Heavy Highway Construction 626 0.97 0.08 0.40 0.14 0.08

Landfill Operations 110 0.80 0.05 0.29 0.14 0.05

Landscaping Activities 1,088 0.54 0.11 0.49 0.07 0.08

Manufacturing Operations 179 0.41 0.03 0.18 0.06 0.03

Municipal-Owned Construction 1,200 0.72 0.12 0.57 0.10 0.10

Transportation/Sales/Services 1,967 4.09 0.37 1.98 0.62 0.35

Residential Construction 3,930 7.37 0.57 2.84 1.02 0.55

Rough Terrain Forklifts 5,532 5.74 0.58 3.47 0.86 0.61

Scrap/Recycling Operations 124 0.37 0.03 0.12 0.06 0.03

Skid Steer Loaders 10,528 3.57 1.05 4.46 0.45 0.78

Special Trades Construction 184 0.09 0.01 0.07 0.01 0.01

Trenchers 4,012 3.35 0.33 2.10 0.52 0.37

TxDOT Construction Equipment 250 0.11 0.01 0.06 0.01 0.01

Utility Construction 3,279 1.78 0.14 0.76 0.19 0.15

Mining and Quarry Operations 984 4.78 0.34 1.57 0.82 0.33

Miscellaneous Equipment 5,836 2.93 0.33 1.68 0.35 0.27

DFW Total 1,940,938 103.30 64.73 806.60 10.78 8.69
Table 4-34: 2018 DFW Area Non-Road Emissions Inventory by Diesel Subcategory

Non-Road

DCE Subsector

Equipment

Population

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Non-Diesel Equipment 2,349,480 23.99 30.49 566.49 0.08 2.48

Agricultural Activities 877 0.37 0.05 0.22 0.00 0.03

Boring and Drilling Equipment 147 0.08 0.01 0.02 0.00 0.00

Brick and Stone Operations 137 0.09 0.02 0.04 0.00 0.01

City and County Road Construction 1,926 0.24 0.02 0.09 0.00 0.01

Commercial Construction 20,979 2.88 0.26 1.21 0.00 0.16

Concrete Operations 170 0.11 0.01 0.05 0.00 0.01

County-Owned Construction 345 0.12 0.01 0.05 0.00 0.01

Cranes 1,472 1.07 0.10 0.29 0.00 0.05

Heavy Highway Construction 1,051 0.50 0.06 0.23 0.00 0.04

Landfill Operations 135 0.11 0.03 0.04 0.00 0.00

Landscaping Activities 1,380 0.34 0.05 0.25 0.00 0.04

Manufacturing Operations 292 0.17 0.02 0.08 0.00 0.01

Municipal-Owned Construction 1,459 0.41 0.05 0.27 0.00 0.04

Transportation/Sales/Services 3,206 1.72 0.24 0.96 0.00 0.13

Residential Construction 2,001 1.10 0.12 0.46 0.00 0.08

Rough Terrain Forklifts 7,728 2.45 0.27 1.63 0.00 0.23

Scrap/Recycling Operations 151 0.06 0.01 0.02 0.00 0.00

Skid Steer Loaders 15,840 3.11 0.60 3.44 0.00 0.51

Special Trades Construction 324 0.07 0.01 0.05 0.00 0.01

Trenchers 5,521 2.05 0.15 0.82 0.00 0.09

TxDOT Construction Equipment 250 0.06 0.01 0.03 0.00 0.00

Utility Construction 7,132 1.96 0.17 0.76 0.00 0.12

Mining and Quarry Operations 383 0.25 0.06 0.08 0.00 0.01

Miscellaneous Equipment 7,540 1.82 0.21 0.97 0.00 0.14

DFW Total 2,429,928 45.15 33.04 578.58 0.12 4.22

The non-road emissions data output from TexN were prepared for photochemical modeling 

using EPS3. Table 4-35: EPS3 Modules for Processing Non-Road Emissions summarizes the 

steps that were taken to process the 2006 and 2018 non-road inventories.

Table 4-35: EPS3 Modules for Processing Non-Road Emissions

EPS3

Module Description

PREAM Convert text-based input files to binary format for further processing.

CNTLEM Apply adjustments for temperature/humidity NOX correction and TxLED.

TMPRL Apply profiles to temporally allocate daily emission totals.

SPCEMS Chemically speciate VOC emissions into olefins, paraffins, etc.

GRDEM Spatially allocate emissions with surrogates and prepare model inputs.

MRGUAM Merge and adjust multiple gridded files for photochemical model input.
When running a summer weekday scenario, the NONROAD model reports 24-hour emission 

totals and does not account for the effects of hourly variation in temperature and humidity on 

NOX emissions. Greater detail on the development of correction equations to account for these 

effects can be found in Appendices F.4 and F.5 of the December 2004 HGB SIP revision. During 

EPS3 processing, the CNTLEM module is also used to apply an hourly temperature/humidity 

NOX correction and the impacts on the 2006 and 2018 non-road DFW inventories are presented 

in Table 4-36: Temperature/Humidity NOX Correction for Non-Road Emissions.

Table 4-36: Temperature/Humidity NOX Correction for Non-Road Emissions

Calendar

Year

Temperature/Humidity

NOX Correction (tpd)

2006 1.19

2018 1.46

The 2006 and 2018 non-road NOX emission totals presented above in Table 4-27 through Table 

4-34 exclude the benefits of Texas Low Emission Diesel (TxLED) fuel. Instead, TxLED benefits 

were accounted for by applying a NOX reduction to the diesel non-road equipment categories 

through use of the EPS3 CNTLEM module. The specific adjustment factors vary by horsepower 

range and certification standard, as summarized in Table 4-37: Non-Road TxLED Adjustments 

by Horsepower and Standard. More detail on development of these post-processing adjustments 

can be found in a September 27, 2001 EPA memorandum entitled Texas Low Emission Diesel 

(LED) Fuel Benefits.

Table 4-37: Non-Road TxLED Adjustments by Horsepower and Standard

Non-Road Diesel Equipment

Standard/Category

TxLED NOX

Reduction Factor

Under 50 Horsepower 0.0%

Base, Tier 0, Tier 1, and Tier 2 6.2%

Tier 3 and Tier 4 4.8%

The 2006 and 2018 non-road TxLED benefits for the 10-county DFW area are presented in 

Table 4-38: 2006 and 2018 DFW Area Non-Road TxLED Benefits.

Table 4-38: 2006 and 2018 DFW Area Non-Road TxLED Benefits

Calendar

Year

TxLED NOX

Reduction (tpd)

2006 4.04

2018 1.55

The activity level for different non-road equipment varies between weekday and weekend day 

types. For example, commercial construction equipment is more commonly used on weekdays 

than weekends. Conversely, recreational boats are more commonly used on weekends than on 

weekdays. The EPS3 TMPRL module is used to adjust the average weekday emissions by 

equipment type for creating Saturday and Sunday day types. Within each day type, TMPRL also 

allocates daily totals to each hour. After the CNTLEM and TMPRL adjustments are made, the 

EPS3 GRDEM module is used to spatially allocate the non-road emissions with surrogates that 

vary based on SCC. The files output from GRDEM are in the binary gridded format required by 
the photochemical model. The 2006 and 2018 non-road emissions output from GRDEM by day 

type for the 10-county DFW area are respectively summarized in Table 4-39: 2006 DFW Area 

Non-Road Emissions Inventory by Day Type and Table 4-40: 2018 DFW Area Non-Road 

Emissions Inventory by Day Type.

Table 4-39: 2006 DFW Area Non-Road Emissions Inventory by Day Type

2006 Day Type NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Monday – Friday Average Weekday 98.06 64.69 806.01 10.78 8.12

Saturday 68.72 94.19 977.67 6.99 5.73

Sunday 50.08 82.22 823.17 5.19 4.43

Table 4-40: 2018 DFW Area Non-Road Emissions Inventory by Day Type

2018 Day Type NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

PM2.5

(tpd)

Monday – Friday Average Weekday 42.13 33.02 578.12 0.11 3.59

Saturday 30.91 47.05 742.31 0.10 2.67

Sunday 23.59 42.00 644.62 0.08 2.14

Comparing Table 4-39 and Table 4-40 with Table 4-27 through Table 4-34 indicates that the 

weekday VOC, CO, and SO2 totals remain unchanged, while the weekday NOX totals are reduced 

by the temperature/humidity and TxLED adjustments presented in Table 4-36 and Table 4-38. 

The PM2.5 totals are also slightly lower in Table 4-39 and Table 4-40 because they include only 

organic carbon, elemental carbon, and sulfate (SO4). The PM2.5 emissions from gasoline, 

compressed natural gas (CNG), and liquefied petroleum gas (LPG) equipment were allocated to 

these PM2.5 categories based on profiles from the EPA SPECIATE Database. The amount 

allocated to these categories for diesel engines varies based on whether exhaust after-treatment 

is needed to meet applicable standards. To obtain these diesel PM2.5 factors, the MOVES2010b 

model was run in default mode to obtain contributions by model year group for 2006-and-older 

and 2010-and newer diesel vehicles. The former group did not need after-treatment while the 

latter group does, and the 2007 through 2009 model years were not included in the analysis 

because they are transition years for the tighter standards. These PM2.5 allocation methods are 

summarized in Table 4-41: Speciation of Non-Road PM2.5 Emissions.

Table 4-41: Speciation of Non-Road PM2.5 Emissions

Non-Road Fuel Type

and/or Standard

PM2.5 Allocation

Approach

Gasoline SPECIATE profile 92113 for non-road gasoline exhaust

CNG and LPG SPECIATE profile 92112 for natural gas combustion

Diesel – Base and Tiers 0-3 MOVES2010b default runs for 2006-and-older without after-treatment

Diesel – Tier 4 MOVES2010b default for 2010-and-newer with after-treatment

For the non-DFW areas of Texas, all of the steps described above are similar for the TexN 

development and EPS3 processing of non-road emission estimates for 2006 and 2018. The 

EPS3 processing for Texas non-road emissions is divided into streams for:

• the 10-county DFW area;
• the eight-county HGB area;

• the remaining 92 of all 110 eastern Texas counties subject to TxLED; and

• the 144 counties of western Texas not subject to TxLED.

The complete EPS3 processing streams for all of these areas are available for both 2006 and 

2018 at ftp://amdaftp.tceq.texas.gov/pub/Nonroad_EI/TEX/2006/ and 

ftp://amdaftp.tceq.texas.gov/pub/Nonroad_EI/TEX/2018/. The following pages contain 

graphical plots of the 2006 and 2018 summer weekday non-road NOX and VOC emissions for 

the DFW area. These plots are respectively entitled Figure 4-12: 2006 Summer Weekday DFW 

Non-Road NOX Emissions Distribution, Figure 4-13: 2006 Summer Weekday DFW Non-Road 

VOC Emissions Distribution, Figure 4-14: 2018 Summer Weekday DFW Non-Road NOX

Emissions Distribution, and Figure 4-15: 2018 Summer Weekday DFW Non-Road VOC 

Emissions Distribution.

For the non-Texas U.S. areas of the modeling domain, the EPA National Mobile Inventory 

Model (NMIM) was run for 2006 and 2018 to obtain non-road emission estimates for each 

county. The NMIM output was processed through EPS3 in a manner similar to that described 

above for non-road emissions within Texas.
Figure 4-12: 2006 Summer Weekday DFW Non-Road NOX Emissions Distribution
Figure 4-13: 2006 Summer Weekday DFW Non-Road VOC Emissions Distribution
Figure 4-14: 2018 Summer Weekday DFW Non-Road NOX Emissions Distribution
Figure 4-15: 2018 Summer Weekday DFW Non-Road VOC Emissions Distribution
4.5 Area Sources

Area sources include commercial, small-scale industrial, and residential activities that use 

materials or operate processes that can generate emissions. These sources of emissions fall 

below the point source reporting levels and are either too numerous or too small to identify 

individually. Emissions from these sources are estimated on a source category basis per county. 

Area source VOC emissions can result from either evaporation or fuel combustion. Examples of 

sources of evaporative losses include printing operations, industrial coatings, degreasing 

solvents, house paints, underground storage tanks, underground tank filling at gasoline service 

stations, and vehicle refueling operations. Fuel combustion sources include stationary source 

fossil fuel combustion at residences and businesses, along with outdoor burning and structural 

fires. With some exceptions, area source emission estimates are obtained by multiplying an 

established emission factor by the appropriate activity or activity surrogate responsible for 

generating the emissions. Human population is the most commonly used activity surrogate for 

many area source categories, while other activity data include the amount of gasoline sold in an 

area, employment by industry type, acres of cropland, etc. Area source modeling estimates were 

based primarily on data from the 2008 and 2011 periodic emissions inventories, which are 

available via TexAER at http://www5.tceq.state.tx.us/texaer/index.cfm.

The NOX, VOC, CO, SO2, NH3, and PM2.5 area source emissions by county from TexAER for 

2008 and 2011, respectively, are presented below in Table 4-42: 2008 DFW Area Source 

Emissions Inventory by County and Table 4-43: 2011 DFW Area Source Emissions Inventory by 

County.

Table 4-42: 2008 DFW Area Source Emissions Inventory by County

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Collin 2.57 20.79 9.18 0.54 3.48 11.30

Dallas 12.53 95.66 25.05 3.27 6.36 16.02

Denton 1.75 19.61 8.42 0.29 5.66 8.26

Ellis 0.59 6.89 5.06 0.12 3.59 9.00

Johnson 0.64 7.42 4.82 0.26 3.44 7.88

Kaufman 0.44 4.86 4.47 0.17 2.73 5.52

Parker 0.41 4.81 4.15 0.15 3.23 7.33

Rockwall 0.22 2.48 1.90 0.06 0.59 2.18

Tarrant 7.88 65.05 17.58 2.24 4.47 11.58

Wise 0.28 3.88 4.14 0.09 2.40 4.62

DFW Total 27.32 231.45 84.77 7.19 35.96 83.70

Table 4-43: 2011 DFW Area Source Emissions Inventory by County

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Collin 2.59 22.27 8.00 0.45 3.49 10.64

Dallas 12.16 89.24 22.74 2.75 6.40 11.67

Denton 1.65 20.59 5.26 0.25 5.66 7.96

Ellis 0.56 6.90 3.33 0.08 3.58 9.11

Johnson 0.62 6.51 3.75 0.19 3.43 7.96
DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Kaufman 0.43 4.96 3.04 0.13 2.72 5.63

Parker 0.39 4.83 2.29 0.11 3.22 7.31

Rockwall 0.22 2.77 1.81 0.05 0.59 2.20

Tarrant 7.36 62.23 15.42 1.87 4.50 10.72

Wise 0.25 3.71 1.51 0.07 2.38 4.69

DFW Total 26.24 224.01 67.15 5.95 35.96 77.89

The 2008 and 2011 area source emissions data from TexAER were prepared for photochemical 

modeling using EPS3. Table 4-44: EPS3 Modules for Processing Area Source Emission 

Inventories summarizes the steps that were taken to prepare the 2006 and 2018 area source 

emission inventories.

Table 4-44: EPS3 Modules for Processing Area Source Emission Inventories

EPS3

Module Description

PREAM Convert text-based input files to binary format for further processing.

CNTLEM Back-cast 2008 emissions to 2006, and project 2011 emissions to 2018.

TMPRL Apply profiles to temporally allocate daily emission totals.

SPCEMS Chemically speciate VOC emissions into olefins, paraffins, etc.

GRDEM Spatially allocate emissions with surrogates and prepare model inputs.

MRGUAM Merge and adjust multiple gridded files for photochemical model input.

As shown, the EPS3 CNTLEM module was used to backcast 2008 DFW area source emission 

estimates from TexAER to 2006, and to project the 2011 DFW area source emission estimates to 

2018. In both cases, a study done under contract by ERG was conducted to develop growth 

factors from 2005 through 2030 based on data available from Moody’s Analytics and the U.S. 

EIA. More detail on this analysis is available within TexAER. The adjusted NOX, VOC, CO, SO2, 

NH3, and PM2.5 area source emissions for 2006 and 2018, respectively, by county are presented 

below in Table 4-45: 2006 DFW Area Source Emissions Inventories by County and Table 4-46: 

2018 DFW Area Source Emission Inventories by County.

Table 4-45: 2006 DFW Area Source Emissions Inventories by County

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Collin 2.60 25.01 8.72 0.55 3.48 11.18

Dallas 13.47 123.06 23.77 3.36 6.39 15.72

Denton 1.76 23.13 8.03 0.30 5.66 8.13

Ellis 0.65 8.90 5.72 0.15 3.60 9.10

Johnson 0.69 9.40 5.61 0.29 3.44 8.00

Kaufman 0.51 6.17 5.88 0.19 2.73 5.69

Parker 0.44 5.79 4.50 0.18 3.23 7.42

Rockwall 0.24 3.08 2.42 0.07 0.59 2.22

Tarrant 8.35 80.82 16.64 2.28 4.49 11.36
DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Wise 0.30 5.08 4.30 0.10 2.40 4.68

DFW Total 29.02 290.46 85.59 7.46 36.01 83.50

Table 4-46: 2018 DFW Area Source Emission Inventories by County

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Collin 2.98 27.67 8.79 0.54 3.50 10.99

Dallas 14.31 113.79 25.71 3.31 6.46 12.45

Denton 1.87 26.72 5.82 0.30 5.66 8.23

Ellis 0.67 9.07 4.25 0.09 3.59 9.31

Johnson 0.73 8.15 4.78 0.22 3.44 8.16

Kaufman 0.52 6.55 4.26 0.16 2.72 5.85

Parker 0.45 6.15 2.82 0.13 3.22 7.47

Rockwall 0.26 3.59 2.44 0.05 0.59 2.30

Tarrant 8.68 78.53 17.43 2.26 4.54 11.28

Wise 0.29 4.71 1.79 0.08 2.38 4.79

DFW Total 30.76 284.94 78.09 7.14 36.09 80.82

The 10-county DFW area source emissions inventory includes 171 different types of SCCs. The 

files available on the TCEQ area source FTP site include a complete set of estimates by county 

and SCC. The 10-county DFW aggregate SCC categories for the area source emissions are 

summarized for 2006 and 2018, respectively, in Table 4-47: 2006 DFW Area Source Emission 

Inventories by Aggregate Category and Table 4-48: 2018 DFW Area Source Emission 

Inventories by Aggregate Category.

Table 4-47: 2006 DFW Area Source Emission Inventories by Aggregate Category

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Agricultural Production 0.29 0.58 5.51 0.00 23.27 5.40

Catastrophic/Accidental Releases 0.00 0.15 0.00 0.00 0.00 0.00

Commercial/Institutional 8.34 77.70 5.54 0.39 0.07 0.59

Construction 0.00 0.00 0.00 0.00 0.00 18.32

Degreasing 0.00 11.61 0.00 0.00 0.00 0.00

Dry Cleaning 0.00 6.96 0.00 0.00 0.00 0.00

Fabricated Metals 0.00 1.01 0.00 0.00 0.00 0.00

Food and Kindred Products 0.00 1.63 1.50 0.00 0.00 4.06

Graphic Arts 0.00 47.24 0.00 0.00 0.00 0.00

Incineration, Burning, and Combustion 0.70 2.01 30.21 0.10 0.14 2.87

Industrial 13.42 8.19 8.16 6.86 0.60 0.41

Landfills 0.00 3.95 0.00 0.00 0.00 0.00

Petroleum Refining, Storage, and Transport 0.00 41.39 0.01 0.00 0.00 0.00

Residential 6.26 5.86 34.65 0.11 0.30 4.99
DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Roads - Paved and Unpaved 0.00 0.00 0.00 0.00 0.00 46.86

Rubber/Plastics 0.00 1.65 0.00 0.00 0.00 0.00

Secondary Metal Production 0.00 0.00 0.00 0.00 0.00 0.00

Surface Coating 0.00 80.04 0.00 0.00 0.00 0.00

Underground Storage Tanks 0.00 0.16 0.00 0.00 0.00 0.00

Waste Animal Emissions 0.00 0.00 0.00 0.00 11.57 0.00

Wastewater Treatment 0.00 0.32 0.00 0.00 0.06 0.00

DFW Area Total 29.02 290.46 85.59 7.46 36.01 83.50

Table 4-48: 2018 DFW Area Source Emission Inventories by Aggregate Category

DFW Area

County

NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Agricultural Production 0.29 0.58 5.51 0.00 23.27 5.40

Catastrophic/Accidental Releases 0.00 0.15 0.00 0.00 0.00 0.00

Commercial/Institutional 9.11 95.37 6.55 0.28 0.06 0.15

Construction 0.00 0.00 0.00 0.00 0.00 12.65

Degreasing 0.00 13.61 0.00 0.00 0.00 0.00

Dry Cleaning 0.00 0.08 0.00 0.00 0.00 0.00

Fabricated Metals 0.00 0.95 0.00 0.00 0.00 0.00

Food and Kindred Products 0.00 1.70 2.25 0.00 0.00 6.07

Graphic Arts 0.00 44.96 0.00 0.00 0.00 0.00

Incineration, Burning, and Combustion 0.59 1.19 17.20 0.09 0.00 2.82

Industrial 13.76 8.94 8.95 6.65 0.51 0.44

Landfills 0.00 4.30 0.00 0.00 0.00 0.00

Petroleum Refining, Storage, and Transport 0.00 40.52 0.01 0.00 0.00 0.00

Residential 7.01 6.31 37.62 0.12 0.33 5.39

Roads - Paved and Unpaved 0.00 0.00 0.00 0.00 0.00 47.90

Rubber/Plastics 0.00 2.23 0.00 0.00 0.00 0.00

Secondary Metal Production 0.00 0.00 0.00 0.00 0.00 0.00

Surface Coating 0.00 63.35 0.00 0.00 0.00 0.00

Underground Storage Tanks 0.00 0.32 0.00 0.00 0.00 0.00

Waste Animal Emissions 0.00 0.00 0.00 0.00 11.85 0.00

Wastewater Treatment 0.00 0.36 0.00 0.00 0.07 0.00

DFW Area Total 30.76 284.94 78.09 7.14 36.09 80.82

The activity level for different area source categories differs between weekday and weekend day 

types. The EPS3 TMPRL module is used to adjust the average weekday emissions by SCC for 

creating Saturday and Sunday day types. Within each day type, TMPRL also allocates daily 

totals to each hour. After the CNTLEM and TMPRL adjustments are made, the EPS3 GRDEM 

module is used to spatially allocate the area source emissions with surrogates that vary based on 

SCC. For example, residential fuel use emissions are spatially allocated to grid cells as a function 

of households. The files output from GRDEM are in the binary gridded format required by the 
photochemical model. The area source output from GRDEM by day type for the 10-county DFW 

area are summarized for 2006 and 2018, respectively, in Table 4-49: 2006 DFW Area Source 

Emission Inventories by Day Type and Table 4-50: 2018 DFW Area Source Emission 

Inventories by Day Type.

Table 4-49: 2006 DFW Area Source Emission Inventories by Day Type

2006 Day Type NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Monday – Friday Average Weekday 29.02 290.46 85.59 7.46 36.01 83.50

Saturday 22.21 136.92 75.57 5.26 35.81 81.90

Sunday 15.41 88.36 65.69 3.06 35.61 80.34

Table 4-50: 2018 DFW Area Source Emission Inventories by Day Type

2018 Day Type NOX

(tpd)

VOC

(tpd)

CO

(tpd)

SO2

(tpd)

NH3

(tpd)

PM2.5

(tpd)

Monday – Friday Average Weekday 30.76 284.94 78.09 7.14 36.09 80.82

Saturday 23.61 137.45 67.38 5.03 35.92 79.27

Sunday 16.46 88.12 56.79 2.92 35.75 77.75

For the non-DFW areas of Texas, all of the steps described above are similar for the area source 

emissions inventory development where TexAER datasets from 2008 and 2011 were adjusted to 

create 2006 and 2018 inventories, respectively. The EPS3 processing for Texas area source 

emissions is divided into streams for:

• the 10-county DFW area;

• the eight-county HGB area;

• the remaining 236 counties of Texas outside of DFW and HGB.

The complete EPS3 processing streams for all of these areas are available for both 2006 and 

2018 at ftp://amdaftp.tceq.texas.gov/pub/Area_EI/2006/ and 

ftp://amdaftp.tceq.texas.gov/pub/Area_EI/2018/. The following pages contain graphical plots 

of the 2006 and 2018 area source NOX and VOC emissions for the DFW area. These plots are 

respectively entitled Figure 4-16: 2006 DFW Area Source NOX Emissions Distribution, Figure 

4-17: 2006 DFW Area Source VOC Emissions Distribution, Figure 4-18: 2018 DFW Area Source 

NOX Emissions Distribution, and Figure 4-19: 2018 DFW Area Source VOC Emissions 

Distribution. For the non-Texas U.S. areas of the modeling domain, area source emission 

estimates from the EPA NEI were used. The 2008 NEI was used for the 2006 inputs, and the 

2011 NEI was used for the 2018 inputs. The area source emission estimates from these NEI 

datasets were processed through EPS3 in a manner similar to that described above for the area 

source emissions within Texas.
Figure 4-16: 2006 DFW Area Source NOX Emissions Distribution
Figure 4-17: 2006 DFW Area Source VOC Emissions Distribution
Figure 4-18: 2018 DFW Area Source NOX Emissions Distribution
Figure 4-19: 2018 DFW Area Source VOC Emissions Distribution
5. BIOGENIC MODELING EMISSIONS

The TCEQ used version 2.1 of the Model for Emissions of Gases and Aerosols from Nature 

(MEGAN) (Guenther, et al., 2012). The MEGAN model code, User’s Guide, and default input 

data are available at http://lar.wsu.edu/megan/index.html. The MEGAN model requires inputs 

by model grid cell area of:

• Emission factors for nineteen chemical compounds or compound groups.

• Plant Functional Types (PFTs).

• Fractional Vegetated Leaf Area Index (LAIv).

• Meteorological information including air and soil temperatures, photosynthetically active 

radiation (PAR), barometric pressure, wind speed, water vapor mixing ratio and 

accumulated precipitation.

5.1 Emission Factor and PFT Inputs

The TCEQ used the default emission factors and PFTs that are provided with the model for the 

entire globe in netCDF format. To process the emission factors and PFTs to the TCEQ air 

modeling domain structures, raster layers of each emission factor file were created in ArcMap 

version 9.3 using the Make NetCDF Raster Layer tool. The Zonal Statistics as Table tool was 

then used to tabulate averages per grid cell for each compound class and CAMx domain. 

5.2 Fractional Vegetated Leaf Area Index Input

Leaf Area Index (LAI) is the one-sided leaf coverage over the same area of land. Fractional 

vegetated Leaf Area Index (LAIv) is LAI divided by the fraction of land defined as vegetated, and 

files for every eight-day period of 2008 are provided on the MEGAN website. The TCEQ created 

2006-specific LAIv data using the level-4 Moderate-Resolution Imaging Spectroradiometer 

(MODIS) global LAI MCD15A2 product. For each eight-day period, the satellite tiles covering 

North America in a Sinusoidal grid were mosaicked together using the MODIS Reprojection 

Tool (MRT). Urban LAI cells, which MODIS excludes, were filled according to a function that 

follows the North American average for four urban land cover types. An urban LAI maximum 

was chosen based on Loughner et al (2012). MODIS’ quality control flags were applied to use 

only the high quality data from the main retrieval algorithm. The resultant LAI was divided by 

the percentage of vegetated PFT per grid cell to yield the final LAIv.

5.3 Meteorological Input

The Weather Research and Forecasting (WRF) meteorological model provided the 

meteorological data needed for MEGAN input, except for PAR. The WRF output was processed 

through the Meteorology-Chemistry Interface Processor (MCIP). The episode-specific satellitebased PAR were obtained from the historical data center operated by the Global Energy and 

Water Cycle Experiment (GEWEX) Continental International Project (GCIP) and GEWEX 

Americas Prediction Project (GAPP) at the University of Maryland, which has a full site address 

of http://metosrv2.umd.edu/~srb/gcip/cgi-bin/historic.cgi. The PAR data were derived from 

hourly GOES satellite imagery of cloud cover, which were processed with a solar irradiation 

model (Pinker and Laszlo, 1992).

5.4 Biogenic Emission Summary

The MEGAN model was run for each 2006 episode day. Since biogenic emissions are dependent 

upon the meteorological conditions on a given day, the same episode-specific emissions for the 

2006 baseline were used in the 2018 future case modeling scenarios. The summaries of biogenic 
emissions by episode day are shown in Table 5-1: Daily Summary of Biogenic Emissions for the 

June 2006 Episode and Table 5-2: Daily Summary of Biogenic Emissions for the AugustSeptember 2006 Episode.

Table 5-1: Daily Summary of Biogenic Emissions for the June 2006 Episode

Episode Day Isoprene 

(tons/day)

Monoterpenes 

(tons/day)

Other VOC 

(tons/day)

Nitrogen Oxide 

(tons/day)

Total VOC 

(tons/day)

5/31/2006 215.84 39.72 119.01 11.64 374.58

6/1/2006 210.25 39.11 116.21 11.32 365.56

6/2/2006 377.91 50.29 171.77 13.82 599.97

6/3/2006 380.30 49.70 171.13 13.54 601.13

6/4/2006 467.68 60.58 201.22 17.40 729.48

6/5/2006 571.09 67.15 231.80 19.05 870.03

6/6/2006 622.20 71.68 252.33 20.23 946.21

6/7/2006 575.44 65.30 234.70 17.85 875.44

6/8/2006 564.75 65.14 233.06 17.92 862.94

6/9/2006 624.09 69.99 251.70 19.38 945.78

6/10/2006 687.47 73.64 265.82 20.22 1026.93

6/11/2006 512.00 64.38 214.69 18.59 791.06

6/12/2006 597.85 67.78 238.48 18.86 904.11

6/13/2006 566.64 65.80 230.37 18.45 862.80

6/14/2006 449.82 53.77 187.85 14.67 691.43

6/15/2006 514.22 61.32 209.33 17.25 784.87

6/16/2006 422.29 56.74 184.59 16.72 663.62

6/17/2006 284.39 46.46 137.32 13.58 468.16

6/18/2006 402.37 51.94 172.93 14.62 627.24

6/19/2006 462.57 56.10 190.84 15.55 709.51

6/20/2006 239.06 44.64 130.08 13.26 413.79

6/21/2006 374.30 54.65 174.27 15.97 603.22

6/22/2006 350.19 54.85 171.18 16.41 576.22

6/23/2006 221.58 45.98 129.08 14.18 396.64

6/24/2006 302.64 49.99 149.02 15.17 501.65

6/25/2006 471.44 58.84 200.56 16.66 730.84

6/26/2006 301.26 43.12 142.10 11.70 486.49

6/27/2006 291.39 41.74 134.71 11.49 467.84

6/28/2006 365.02 48.35 158.81 13.42 572.18

6/29/2006 392.48 51.28 170.41 14.23 614.18

6/30/2006 386.33 53.29 171.68 15.17 611.30

7/1/2006 386.03 52.84 169.97 14.83 608.84

7/2/2006 337.00 49.72 153.85 14.12 540.57
Table 5-2: Daily Summary of Biogenic Emissions for the August-September 2006 

Episode

Episode Day Isoprene 

(tons/day)

Monoterpenes 

(tons/day)

Other VOC 

(tons/day)

Nitrogen Oxide 

(tons/day)

Total VOC 

(tons/day)

8/15/2006 588.98 69.50 232.58 18.61 891.05

8/16/2006 683.25 75.31 257.01 19.88 1015.57

8/17/2006 673.03 75.49 255.37 20.22 1003.89

8/18/2006 624.47 74.96 245.79 20.53 945.22

8/19/2006 566.77 70.02 228.30 19.27 865.09

8/20/2006 543.67 68.02 219.99 18.81 831.68

8/21/2006 510.58 63.47 204.54 17.67 778.58

8/22/2006 322.45 51.03 145.91 14.96 519.39

8/23/2006 409.52 53.68 164.71 15.00 627.91

8/24/2006 522.62 64.45 201.85 18.11 788.92

8/25/2006 623.05 70.15 233.54 19.14 926.74

8/26/2006 538.64 65.19 211.70 18.09 815.53

8/27/2006 264.01 44.61 128.78 12.98 437.40

8/28/2006 64.40 28.29 59.85 8.22 152.53

8/29/2006 224.45 38.57 113.42 10.11 376.44

8/30/2006 265.08 40.02 125.45 10.25 430.55

8/31/2006 364.13 49.27 157.06 13.05 570.45

9/1/2006 341.07 49.71 154.27 13.33 545.04

9/2/2006 155.06 37.52 99.47 10.28 292.05

9/3/2006 68.18 27.95 62.04 7.37 158.17

9/4/2006 23.79 20.35 40.23 4.80 84.37

9/5/2006 142.67 30.52 85.08 7.56 258.26

9/6/2006 203.53 33.67 105.31 8.21 342.51

9/7/2006 201.75 34.72 106.52 8.72 342.99

9/8/2006 177.03 36.70 101.28 10.00 315.00

9/9/2006 179.80 38.10 104.43 10.40 322.33

9/10/2006 240.09 42.65 124.92 11.55 407.67

9/11/2006 241.79 42.06 122.53 11.22 406.37

9/12/2006 233.88 39.40 120.21 10.00 393.48

9/13/2006 164.82 29.88 91.07 7.17 285.77

9/14/2006 218.39 35.92 106.26 9.59 360.57

9/15/2006 260.56 46.57 131.23 13.47 438.36

Isoprene and other biogenic VOC emissions were plotted to visually determine the location of 

emissions matched to known forested areas as shown in Figure 5-1: Biogenic Isoprene

Emissions on June 12, 2006 for the 4 km Domain. CAMx output concentrations of the same 

VOC for the same time period are also plotted to ensure concentrations follow emission 

magnitudes. An example isoprene concentration plot for June 12, 2006 at 12:00 is displayed in 

Figure 5-2: Modeled CAMx Isoprene Concentrations for June 12, 2006 at 12:00 CST.
Figure 5-1: Biogenic Isoprene Emissions on June 12, 2006 for the 4 km Domain
Figure 5-2: Modeled CAMx Isoprene Concentrations for June 12, 2006 at 12:00 

CST

6. REFERENCES

Guenther, A., Jiang, X., Heald, C., Sakulyanontvittaya, T., Duhl, T., Emmons, L., et al., 2012. 

The Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGAN2.1): an 

extended and updated framework for modeling biogenic emissions. Geoscientific Model 

Development, 1471-1492.

Loughner, Christopher P., Dale J. Allen, Da-Lin Zhang, Kenneth E. Pickering, Russell R. 

Dickerson, Laura Landry, 2012. Roles of Urban Tree Canopy and Buildings in Urban Heat 
Island Effects: Parameterization and Preliminary Results. J. Appl. Meteor. Climatol., 51, 1775–

1793.

Pinker, R.T. and I. Laszlo, 1992. Modeling surface solar irradiance for satellite applications on a 

global scale. J. Appl. Meteor., 31, 194-211.