Hood County Emission Inventory Review

Transcription

FY14-15
PGA 582-14-40697 FY14-1
Task 3.1
Amendment 1
Report
Review of Hood County
Ozone Precursor Emission Inventory
for Point, Off-road and Area Sources
PREPARED UNDER A GRANT FROM THE
TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
The preparation of this report was financed through grants from the State of Texas
through the Texas Commission on Environmental Quality.
The content, findings, opinions and conclusions are the work of the author(s) and
do not necessarily represent findings, opinions or conclusions of the TCEQ.
Prepared for:
Michelle McKenzie
Hood County Clean Air Coalition
123 E. Pearl St. #200
Granbury, Texas 76048
Prepared by:
John Grant, Sue Kemball-Cook
and Greg Yarwood
ENVIRON International Corporation
773 San Marin Drive, Suite 2115
Novato, California, 94998
www.environcorp.com
P-415-899-0700
F-415-899-0707
March 2015
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CONTENTS
EXECUTIVE SUMMARY ......................................................................................................... 1
1.0 INTRODUCTION ............................................................................................................. 4
1.1 Background and Purpose.................................................................................................4
1.2 All Source Emissions Overview ........................................................................................6
1.3 Anthropogenic Source Emissions Overview ....................................................................7
2.0 OFF-ROAD EMISSIONS REVIEW ...................................................................................... 9
2.1 Overview of emissions inventory ....................................................................................9
2.2 Analysis ..........................................................................................................................13
2.2.1 Off-Road Equipment Emissions Calculated Using the TexN Emission
Model ..................................................................................................................13
2.2.2 Off-Road Equipment Emissions Calculated Outside of the TexN
Emission Model ...................................................................................................14
3.0 AREA SOURCE EMISSIONS REVIEW ............................................................................... 16
3.1 Overview of emissions inventory ..................................................................................16
3.2 Analysis ..........................................................................................................................23
3.2.1 Oil and Gas Emissions .........................................................................................23
3.2.2 Fuel Combustion Emissions ................................................................................26
3.2.3 Gasoline Distribution Emissions .........................................................................26
4.0 POINT SOURCE EMISSIONS REVIEW.............................................................................. 28
4.1 2012 Point Source Emissions .........................................................................................28
4.1.1 Emission Summary ..............................................................................................28
4.2 Point Source Emission Comparison to NEI ....................................................................31
4.3 Newly Permitted Power Plant Units ..............................................................................33
4.3.1 DeCordova Power Plant Expansion.....................................................................34
4.3.2 Wolf Hollow II Power Plant Expansion................................................................35
5.0 RECOMMENDATIONS................................................................................................... 37
6.0 REFERENCES ................................................................................................................ 38
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APPENDICES
Appendix A. Hood County Off-road and Area Source Emissions
Appendix B. Hood County Point Source Emissions
TABLES
Table 2-1.
2012 off-road emission inventory data sources. ....................................................9
Table 2-2.
Hood County 2012 off-road emissions..................................................................10
Table 3-1.
Population changes in Hood County between 2006 and 2015. Data
source: http://www.dshs.state.tx.us/chs/popdat/default.shtm ..........................16
Table 3-2.
Hood County 2012 area source emissions. ...........................................................19
Table 3-3.
2011 and 2012 area source emissions comparison. .............................................21
Table 3-4.
Oil and gas emissions methods summary by source category. ............................25
Table 3-5.
Texas statewide annual gasoline consumption. ...................................................27
Table 4-1.
Top emitting NOx and VOC point sources in Hood County. .................................30
Table 4-2.
Hood County point source emissions by industrial sector....................................31
Table 4-3.
2011 NEI and 2012 TCEQ NOx ozone season day point source
emissions by year by facility. .................................................................................32
Table 4-4.
Number of facilities by SIC in the 2011 NEI and 2012 TCEQ point
source emission inventory. ...................................................................................33
Table 4-5.
NOx and VOC emissions for facilities that did not report emissions in
both years, 2011 and 2012. ...................................................................................33
Table 4-6.Hourly maximum allowable emission rate (source: TCEQ Permit Number
107569) and calculated daily maximum allowable emission rate from
additional permitted units at the DeCordova Power Plant. .................................35
Table 4-7. Hourly maximum allowable emission rate (source: TCEQ Permit Number
83638 and PSDTX1110) and calculated daily maximum allowable
emission rate from additional permitted units at the Wolf Hollow II
Power Plant Expansion. .........................................................................................36
FIGURES
Figure 1-1.
2012 Hood County NOx and VOC emissions by source category for NOx
(left) and VOC (right). ..............................................................................................7
Figure 1-2.
Hood County 2006 and 2012 Hood County anthropogenic emissions by
sector for NOx (left) and VOC (right).......................................................................8
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Figure 2-1.
Hood County 2012 off-road NOx emissions emission by source
category. ................................................................................................................11
Figure 2-2.
Hood County 2012 off-road VOC emissions emission by source
category. ................................................................................................................11
Figure 2-3.
Comparison of 2011 NEI and 2012 TCEQ NOx off-road emissions
emission by source category for Hood County. ....................................................12
Figure 2-4.
Comparison of 2011 NEI and 2012 TCEQ VOC off-road emissions
emission by source category for Hood County. ....................................................12
Figure 3-1. 2000-2014 oil and gas production (left) and well count (right) totals for
Hood County based on TRC oil and gas activity data. (Well counts are
as of beginning of February for each year). ..........................................................18
Figure 3-2. 2000-2014 oil and gas production from the Barnett Shale. .....................................18
Figure 3-3. Natural gas productivity within the Barnett Shale. Figure from the Texas
Bureau of Economic Geology:
http://www.utexas.edu/news/files/Productivity-Tiers-2.jpg. ..............................19
Figure 3-4. Hood County 2012 area source NOx emissions emission by source
category. ................................................................................................................20
Figure 3-5. Hood County 2012 area source VOC emissions emission by source
category. ................................................................................................................20
Figure 3-6. Hood County 2012 oil and gas source NOx emissions by source category. .............22
Figure 3-7. Hood County 2012 oil and gas source VOC emissions by source category. .............22
Figure 4-1.
Map showing location of Hood County point sources in the TCEQ 2012
NOx emission inventory (facility name labels not provided for facilities
emitting 0.03 tpd NOx or less). .............................................................................29
Figure 4-2.
Hood County ozone season day point source emissions from the 2011
NEI and 2012 TCEQ inventories.............................................................................31
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LIST OF ACRONYMS AND ABBREVIATIONS
ARPDB
BACT
BSASI
CAMD
CAMS
CEM
CO
CTG
DFW
DLN
EGU
EIA
EPA
hr
HAP
HCCAC
Kg
kW
M
MEGAN
MM
MOBILE6.2
MOVES
NAAQS
NEI
NNA
NO
NOx
OSD
ppb
SCC
SCR
scf
SIC
SIP
STARS
TAC
TCEQ
Ton
tpd
TRC
VMT
VOC
yr
Acid Rain Program Database
Best available control technology
Barnett Shale Area Special Inventory
Clean Air Markets Division
Continuous Air Monitoring Station
Continuous emissions monitor
Carbon Monoxide
Combustion turbine generation
Dallas-Fort Worth Area
Dry low-NOx
Electric generating unit
Energy Information Administration
Environmental Protection Agency
Hour
Hazardous air pollutant
Hood County Clean Air Coalition
Kilogram
Kilowatt
Thousand
Model of Emissions of Gases and Aerosols from Nature
Million
Mobile source emissions model (predecessor to MOVES)
Motor Vehicle Emissions Simulator
National Ambient Air Quality Standard
National Emission Inventory
Near Non-Attainment Area (for the ozone NAAQS)
Nitric Oxide
Oxides of Nitrogen
Ozone season day
parts per billion
Source Classification Code
Selective Catalytic Reduction
Standard cubic feet
Standard industrial classification
State Implementation Plan (for the ozone NAAQS)
State of Texas Air Reporting System
Texas Administrative Code
Texas Commission on Environmental Quality
English short ton (2000 pounds)
Ton per day
Texas Railroad Commission
Vehicle Miles Travelled
Volatile organic compound
Year
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EXECUTIVE SUMMARY
The purpose of this study is to review the most recent Texas Commission on Environmental
Quality (TCEQ) ozone precursor emission inventories available for Hood County for off-road,
area (non-point) and point sources to identify sources of emissions that are missing from the
inventory or are not well-characterized. Through analysis of the emission inventory we aimed
to identify sources of emissions that are overestimated or underestimated, accompanied by
high levels of uncertainty, or for which more accurate or detailed emissions are available and to
determine source categories for which further emission inventory development efforts are
warranted.
Before focusing on specific emission categories we first reviewed the entire Hood County
emission inventory of ozone precursors from human activities (anthropogenic emissions) and
natural sources (biogenic emissions). Biogenic emissions are emitted by sources such as trees,
agricultural crops and microbial activity in soils. The most recent available emission inventory of
anthropogenic and biogenic emissions for Hood County is TCEQ’s 2012 emission inventory.
Hood County-wide 2012 total emission estimates are 11 tons per day (tpd) of nitrogen oxides
(NOx) and 78 tpd of volatile organic compounds (VOC). Biogenic emissions are the largest VOC
category comprising 68 tpd of Hood County VOC emissions. Presence of abundant biogenic VOC
emissions ensures there are typically sufficient VOC to allow ozone formation. This means local
emissions control strategies aimed at reducing the local contribution to Hood County ozone
should focus on reducing NOx emissions.
The three largest contributors to Hood County NOx emissions are: point sources (3.3 tpd, 29%),
oil and gas area sources (2.9 tpd, 25%) and on-road vehicles (2.7 tpd, 23%). Together, these
three source categories account for over three-quarters of Hood County’s NOx emissions.
Smaller NOx emissions source categories, off-road (1.3 tpd, 11%), biogenics (1.2 tpd, 11%), and
non-oil and gas area sources (0.1 tpd, 1%) together account for less than one-quarter of Hood
County NOx emissions. Biogenic sources are the largest VOC category comprising 87% (68 tpd)
of Hood County VOC emissions. Anthropogenic sources account for 13% of VOC emissions with
contributions from oil and gas area sources (7%; 5.1 tpd), non-oil and gas area sources (3%; 2.2
tpd), point sources (1%; 1.0 tpd), on-road vehicles (1%; 0.9 tpd), and off-road sources (1%; 0.7
tpd).
Electric power generation accounts for 58% of point source NOx emissions while oil and gasrelated point sources account for the remaining 42%. TCEQ has approved a permit to construct
and operate two additional natural gas-fueled combustion turbine generation (CTG) units at the
DeCordova Power Plant and has also approved a permit to construct and operate two
additional CTG units at the Wolf Hollow Power Plant. For the DeCordova Power Plant
expansion, estimated daily maximum total permitted NOx emissions for these units are 1.8 tpd
to 2.9 tpd. Estimated daily maximum NOx emissions from the DeCordova Power Plant
expansion represent potential increases of 18% to 28% from all Hood County anthropogenic
sources relative to the 2012 TCEQ emission inventory (see Section 4.3.1 for further
information). For the Wolf Hollow Power Plant expansion, estimated daily maximum total
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permitted NOx emissions for these units are 0.8 tpd NOx. Estimated daily allowable NOx
emissions from the Wolf Hollow Power Plant expansion represent potential increases of 8%
from all Hood County anthropogenic sources relative to the 2012 TCEQ emission inventory (see
Section 4.3.2 for further information). Estimated daily allowable NOx emission estimates
provided above are not expected to represent ozone season daily estimates. Ozone season
daily emission estimates will depend on the power plant electric load during the ozone season;
since the new units are peaking units it is expected that during summer months they may
operate at a higher load.
Oil and gas area source NOx emissions account for 96% of area source NOx emissions with 94%
of oil and gas area sources from compressor engines. Compressor engine emissions are
estimated based on the TCEQ Barnett Shale Area Special Inventory (BSASI)1, which was
developed using local data supplied by energy exploration and production companies active in
the Barnett Shale.
Recommended improvements to the TCEQ 2012 area, off‐road, and point source emissions
inventories are listed below in order of importance. NOx emissions updates are a higher priority
than VOC emission updates because ozone formation in Hood County is expected to be NOx
limited because of substantial biogenic VOC emissions that are not controllable. None of the
recommended changes are expected to affect the largest Hood County NOx emission source
categories (i.e. power plants and oil and gas area source compressor engines) and accordingly
none of these updates is considered a high priority.
Inventory Improvements and Recommendations for Implementation
1. Switching locomotive emissions associated with Cresson rail yard are not included in the
2012 emission inventory. “Switching” is the process of sorting and re-combining rolling
stock at a rail yard.
Recommendation: Develop Cresson rail yard emission inventory for inclusion in future
inventories (Section 2.2.2).
2. Update oil and gas activity/equipment area source emissions data (Section 3.2.1).
Recommendation: Update equipment configuration and ancillary data used in emissions
calculations for heaters, pneumatic pumps, fugitive devices, dehydrators, and well
completions.
3. Verify data underlying gasoline distribution emission inventory (Section 3.2.3).
Recommendation: Obtain gasoline distribution volume estimates from local/state
agencies to verify that reasonable gasoline throughput volumes are used in the ERG
(2008a) study.
1
“Barnett Shale Area Special Inventory, Phase One”, TCEQ, 2009,
http://www.tceq.texas.gov/assets/public/implementation/air/ie/pseiforms/Barnett%20Shale%20Area%20Special%20
Inventory.pdf, “Barnett Shale Phase Two Special Inventory Data”, TCEQ,
http://www.tceq.texas.gov/assets/public/implementation/air/ie/pseiforms/summarydatainfo.pdf
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Power plants are one of the largest sources of NOx emissions in Hood County; in 2012 they
comprised 16% of the Hood County NOx emission inventory. Expansion of the Wolf Hollow and
DeCordova power plants through addition of new CTGs would increase NOx emissions.
Because proposed CTGs would operate as peaking units, they would likely have their highest
emissions on hot summer days when Hood County is most likely to experience high ozone.
Therefore, plans to develop new units should be monitored closely and new NOx emissions
analyzed to determine their magnitude, variability and potential ozone impacts.
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1.0 INTRODUCTION
1.1 Background and Purpose
Hood County is located in the southwestern part of the Dallas–Fort Worth–Arlington
Metropolitan Statistical Area (DFW)2. On May 21, 2012, the United States Environmental
Protection Agency (EPA) published in the Federal Register final designations for the 2008 eighthour ozone standard. Hood County was and is currently designated as
attainment/unclassifiable for eight-hour ozone.3 Ground level ozone monitoring data are used
to calculate what are termed “design values” (DV) that determine whether an area is in
compliance with the National Ambient Air Quality Standard (NAAQS) for ozone. “Design values”
are indicators of attainment status that are expressed in the same units (e.g., parts ozone per
billion parts ambient air) but are not directly comparable with ambient measurements. The
Texas Commission on Environmental Quality (TCEQ) operates one Continuous Air Monitoring
Station (CAMS) in Hood County, the Granbury monitor (CAMS 73). As of the end of 2014, the
Granbury monitor had a design value of 76 parts per billion (ppb) which exceeds the 2008
ozone NAAQS of 75 ppb.
Under the Clean Air Act, the EPA is required to review the NAAQS periodically. On November
26, 2014, the EPA announced their proposal to lower the NAAQS to a value in the 65-70 ppb
range and to finalize the NAAQS by October, 2015. Designations of attainment status are
anticipated by October 2017 and will likely be based on monitored ozone levels in the 20142016 timeframe. The Granbury (CAMS 73) monitor’s design value is higher than the current
ozone standard and with the anticipated lowering of the ozone standard the Granbury monitor
may remain out of compliance. Because failure to comply with the NAAQS carries adverse
public health impacts and significant economic penalties, ozone air quality planning is
important for Hood County. Accurate and up-to-date emission inventories of ozone precursors
are a key component of air quality planning.
Emission inventories are used to assess the nature of an area’s ozone problem and can help
answer questions such as whether ozone formation in the region is limited by the amount of
available NOx or VOC as well as which types of emissions sources are good candidates for
emissions controls that could reduce the area’s ozone levels. Emission inventories are also
required for ozone modeling. Ozone models are used to gain a better understanding of an
area’s ozone problem and to test potential impacts of emission control strategies.
Following EPA’s 2010 reconsideration of the ozone standard, the TCEQ began preparing for
State Implementation Plan (SIP) development by planning for ozone modeling that would
coordinate efforts for all Texas Near Non-Attainment Areas (NNAs). The TCEQ developed an
emission inventory for a 2006 ozone modeling episode. The purpose of the ozone modeling was
2
3
http://www.census.gov/population/metro/data/def.html
https://www.tceq.texas.gov/airquality/sip/dfw/dfw-ozone-history
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to develop and test emissions control strategies that would ensure that each NNA would attain
the new ozone standard. The 2006 emission inventory and air quality modeling are now dated
and no longer adequately reflect present emission levels due to changes to parameters
important to emission inventory development. Examples of these parameters include the
amount of oil and gas activity and ongoing changes to on-road and off-road equipment fleets as
a result of fleet turnover and changes in vehicle and equipment populations. The TCEQ is
currently developing a 2012 ozone modeling episode for use by the Texas NNAs. This ozone
modeling episode will eventually be available to the Hood County Clean Air Coalition (HCCAC)
for emission control strategy development and evaluation.
The TCEQ selected a June, 2012 episode which will serve as an initial base case modeling
episode. The TCEQ plans to eventually expand this modeling episode to include the entire 2012
ozone season. The purpose of the 2012 base case episode is to determine whether the
photochemical model is able to replicate observed ozone and precursors during a historical
period of high ozone. If the model is able to reproduce the past ozone episode with reasonable
accuracy it may then be used to make projections of future year ozone and to evaluate effects
of proposed emission control strategies.
The TCEQ recommended that NNAs review emission inventories that may be used for ozone
modeling or may be used as the basis for future year emission inventory development. The
purpose of this report is to provide a review of the most recent 2012 TCEQ anthropogenic
emission inventories for Hood County for off-road, area and point sources. Point sources are
large stationary emissions sources that exceed a specified emissions threshold and therefore
are tracked individually in the emissions inventory. Area sources are sources that may be
spread out geographically and are small individually (such as an oil well), but, taken together,
may constitute a sizeable amount of emissions. Off-road mobile source emissions are from
mobile and portable internal combustion powered equipment not generally licensed or
certified for highway use.
In this report we summarize the TCEQ 2012 area, off-road and point source emission inventory
for Hood County, examine emissions estimation methodology and emission trends, and identify
emissions categories that are overestimated or underestimated, accompanied by high levels of
uncertainty, or for which more accurate or detailed emissions are available. The contents of the
remainder of this report are as follows:
Section 2: 2012 off-road emissions review,
Section 3: 2012 area source emissions review,
Section 4: 2012 point source emissions review, and
Section 5: Recommendations for emission inventory improvement.
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1.2 All Source Emissions Overview
The TCEQ 2012 emission inventory is summarized below to establish the relative importance of
point, area, and off-road sources with respect to other emissions source categories (e.g. onroad mobile sources, biogenics) in the Hood County emission inventory.
At the time this analysis was performed, 2012 was the most recent year for which a full Hood
County emission inventory (i.e. anthropogenic and biogenic emissions) was available. Area
source emissions presented in this section have been divided into two components: non-oil and
gas area sources and oil and gas area sources. This division facilitates understanding of
contributions from oil and gas area sources; oil and gas sources comprise a larger fraction of the
area source NOx and VOC inventories than any other single area emissions source category.
Figure 1-1 shows NOx and VOC emissions by source category in Hood County for 2012. Hood
County-wide 2012 total emission estimates are 11.4 tpd NOx and 78.3 tpd VOC. The largest
three emissions source categories, point sources (3.3 tpd, 29%), oil and gas area sources (2.9
tpd, 25%), and on-road vehicles (2.7 tpd, 23%), account for over three-quarters of Hood County
NOx emissions. Smaller NOx emissions sources, off-road (1.3 tpd, 11%), biogenic (1.2 tpd, 11%),
and non-oil and gas area (0.1 tpd, 1%) sources, together account for less than one-quarter of
Hood County total NOx emissions. Biogenic sources are the largest VOC category comprising
87% (68.4 tpd) of Hood County total VOC emissions. Anthropogenic sources account for 13% of
VOC emissions with contributions from: oil and gas area sources (7%; 5.1 tpd), non-oil and gas
area sources (33%; 2.2 tpd), point sources (1%; 1.0 tpd), on-road vehicles (1%; 0.9 tpd), and offroad sources (1%; 0.7 tpd).
Biogenic emissions estimates were developed by the TCEQ using the Model of Emissions of
Gases and Aerosols from Nature (MEGAN; Guenther et al., 2012) version 2.10; MEGAN
emissions provide hourly day-specific emissions that depend on photosynthetically active solar
radiation and temperature as well as other inputs such as land cover. Episode average biogenic
emissions were extracted by ENVIRON from a draft TCEQ 2012 biogenic emission inventory for
Hood County from data available at the time this analysis was performed. This TCEQ inventory
included biogenic emissions for the period June 14-30, 2012 only. Extension of the average
period across the entire episode can be done in the future, but is unlikely to significantly
change the ratio of biogenic to total VOC emissions.
Ozone formation depends on the amount of NOx and VOC present as well as on the ratio of
VOC to NOx where the ratio is taken in terms of parts per billion by carbon (ppbC) per ppb.
When the VOC/NOx ratio is higher than about 10 ozone formation is limited by the amount of
available NOx and reducing NOx tends to decrease peak ozone concentrations. However, if the
VOC/NOx ratio is less than about 7 reducing NOx tends to increase ozone in the vicinity of NOx
emission sources (e.g., an urban area) and the area is said to be VOC-limited. In this situation,
ozone is suppressed in the urban area due to titration by large amounts of fresh NO emissions.
When NOx emissions are reduced suppression of ozone by NO is lessened and ozone increases.
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For Hood County, the emission inventory VOC/NOx ratio is 23 ppbC/ppb, which is well within
the NOx-limited regime. The presence of abundant biogenic VOC emissions ensures that there
are sufficient VOCs to allow ozone formation and that ozone formation is limited by the amount
of available NOx. This means local emissions control strategies should focus on reducing NOx
emissions.
Figure 1-1. 2012 Hood County NOx and VOC emissions by source category for NOx (left) and
VOC (right).
1.3 Anthropogenic Source Emissions Overview
The TCEQ 2006 and 2012 emission inventories are compared below to evaluate Hood County
emissions trends between 2006 and 2012. Figure 1-1 shows NOx and VOC anthropogenic
emissions by source category in Hood County for 2006 and 2012. Hood County-wide
anthropogenic NOx emissions decreased from 12.3 tpd in 2006 to 10.2 tpd in 2012 (-17%). The
following NOx emissions source categories showed decreases from 2006 to 2012: on-road
vehicles (-46%), off-road mobile sources (-40%) and non-oil and gas area sources (-25%). Point
sources and oil and gas area source NOx emissions increased by 9% and 40%, respectively.
Hood County-wide anthropogenic VOC emissions decreased from 13.1 tpd in 2006 to 10.0 tpd
in 2012 (-24%). The following VOC emissions source categories showed decreases from 2006 to
2012: oil and gas sources (-37%), on-road vehicles (-31%), and non-oil and gas area sources (9%). Point source VOC emissions and off-road source VOC emissions increased by 70% and 3%,
respectively.
Changes to on-road emissions result from changes in vehicle activity (vehicle miles traveled;
VMT) and fleet turnover over time. VMT activity trends are typically consistent with human
population trends. Hood County population increased by 8% from 2006 to 20124; decreases in
NOx and VOC emissions from on-road vehicles are likely the result of fleet turnover to new
vehicles between 2006 and 2012 rather than decreases in vehicle activity. Similar to on-road
4
http://www.dshs.state.tx.us/chs/popdat/default.shtm
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vehicles changes in emissions from off-road sources are the result of both changes in activity
(i.e. equipment population and annual use) and fleet turnover to new equipment. Decreases in
off-road NOx emissions and increases in off-road VOC emissions from 2006 to 2012 are due to
combination of equipment activity changes and the effect of fleet turnover. Changes in oil and
gas area source emissions from 2006 to 2012 are likely due to a combination of factors: oil and
gas activity increases from 2006 to 2012 as well as improvements in TCEQ’s oil and gas area
source emissions estimation methodology. Development of the 2012 emission inventory is
based on a collection of Barnett Shale survey data in studies such as the BSASI. This level of
detailed area-specific data was not available in 2006. Point source emission increases are due to
increased activity for the point source sector between 2006 and 2012.
Figure 1-2. Hood County 2006 and 2012 Hood County anthropogenic emissions by sector for
NOx (left) and VOC (right).
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2.0 OFF-ROAD EMISSIONS REVIEW
Off-road mobile source emissions are from mobile and portable internal combustion powered
equipment not generally licensed or certified for highway use. Off-road emissions equipment
categories span a wide range of equipment types such as lawn and garden equipment, heavyduty construction equipment, aircraft and locomotives. Off-road emissions for many of these
categories are calculated using EPA’s NONROAD computer model. TCEQ has developed a Texasspecific application of the NONROAD model called TexN (ERG, 2014) for counties within Texas
and this model is described below.
2.1 Overview of emissions inventory
ENVIRON obtained the most recent 2012 emission inventory for Hood County from several
sources based on input from TCEQ staff (TCEQ, 2014a). The most recent source of data
available for each emissions source category was used. Table 2-1 contains a listing of data
sources. Hood County off-road source emissions by county and source category are presented
in Appendix A.
Table 2-1.
Off-road Type
c
Locomotives
Drill Rigs
2012 off-road emission inventory data sources.
b
c
Other Off-road
d
Equipment
Emissions Data Source
Source: TCEQ ftp site ftp://amdaftp.tceq.texas.gov/pub/
a
Reference: No reference available
Source: Personal communication with TCEQ staff (TCEQ, 2015)
Reference: ERG (2010a) methodology with 2012 spudding activity
Source: TCEQ ftp site ftp://amdaftp.tceq.texas.gov/pub/
Reference: TexN model, version 1.6.1 (ERG, 2014)
a
Previously based on ERG (2010b). Emissions have been updated, but new documentation is not yet available.
The TCEQ 2012 inventory includes no emissions from aviation sources in Hood County.
c
Average day emissions available from TCEQ were used.
d
Average day emissions were estimated based on weekday, Saturday, and Sunday emissions available from TCEQ according to
the following equation: (weekday emissions*5 + Saturday emissions + Sunday emissions)/7.
b
The off-road sector is made up of various types of equipment that change locations at least
once each year (or in certain cases once each season). Off-road sector emissions for many types
of off-road equipment can be estimated with the U.S. EPA’s NONROAD model5. A Texas nonroad emissions model, the TexN model (ERG, 2014) is also available. The TCEQ developed the
TexN model which runs the NONROAD model with Texas-specific data for equipment activity
parameters such as equipment population, equipment annual hours of activity, seasonal usage
patterns, and activity growth to the extent that such Texas-specific data is available primarily
from TCEQ-funded studies as described in ERG (2008b) and ERG (2014). The TexN model is
described in more detail in Section 2.2.1. Off-road sources not in the TexN model (locomotives,
5
http://www.epa.gov/otaq/nonrdmdl.htm
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March 2015
drill rigs, and aviation) are estimated in stand-alone analyses based on the unique types of
engines and activities associated with each of these off-road sources.
Table 2-2 shows Hood County NOx, VOC and CO off-road emissions from the 2012 TCEQ
inventory and the 2011 EPA National Emissions Inventory (NEI). The 2011 NEI is shown for
comparison purposes; however, the 2011 NEI is an annual emission inventory while the 2012
TCEQ inventory is an ozone season emission inventory hence differences in the two inventories
are based not only on (1) differences in equipment activity source data and (2) changes in
activity and emission factors from 2011 to 2012, but also due to seasonal usage profiles.
Therefore, emissions differences for a source category for which activity varies considerably by
season (e.g. pleasure craft) may be dominated by differences in the temporal scope of the two
inventories.
Table 2-2.
Pollutant
NOx
VOC
CO
1
2
Hood County 2012 off-road emissions.
Emissions (tpd)
2012 TCEQ1
2011 NEI2
1.33
1.29
0.51
0.75
5.71
3.89
Ozone season day inventory
Annual inventory
Figure 2-1 and Figure 2-2 show 2012 off-road emission contributions by source category for
Hood County for NOx and VOC. The three largest contributors to off-road NOx emissions are
agricultural equipment (40%), construction and mining equipment (26%), and drilling
equipment (20%). The top three NOx emissions sources are all primarily made up of diesel
engine fleets and together account for 86% of off-road source NOx emissions. Over threequarters (79%) of VOC emissions are from the top two contributors (pleasure craft and lawn
and garden equipment). Off-road source categories with the largest contributions to VOC
emissions have gasoline engine fleets.
Figure 2-3 and Figure 2-4 show a comparison of 2012 TCEQ inventory NOx and VOC emissions
by source category with 2011 NEI estimates. Three source categories that stand-out for their
differences between 2011 and 2012 emissions are agricultural equipment (38% higher NOx
emissions in the TCEQ inventory), drilling equipment (39% lower NOx emissions in the TCEQ
inventory), and pleasure craft (84% higher emissions in the TCEQ inventory). Differences
between 2012 TCEQ and 2011 NEI drilling emissions are due to changes in drill rig activity from
2011 to 2012 as explained below. Differences between 2012 TCEQ and 2011 NEI agricultural
equipment emissions are due primarily to use of Texas-specific population updates in TexN as
described below while differences between 2012 TCEQ and 2011 NEI pleasure craft emissions
are due to both updates in TexN to pleasure craft population and differences in the temporal
basis of the emission inventory. Since the 2012 TCEQ inventory is for an average ozone season
day which occurs in summer there is more pleasure craft (boating) activity and associated
emissions in the 2012 TCEQ inventory than in the 2011 NEI which is an annual inventory based
on annual average pleasure craft activity.
10
March 2015
Figure 2-1. Hood County 2012 off-road NOx emissions emission by source category.
Figure 2-2. Hood County 2012 off-road VOC emissions emission by source category.
11
March 2015
Figure 2-3. Comparison of 2011 NEI and 2012 TCEQ NOx off-road emissions emission by
source category for Hood County.
Figure 2-4. Comparison of 2011 NEI and 2012 TCEQ VOC off-road emissions emission by
source category for Hood County.
12
March 2015
2.2 Analysis
2.2.1 Off-Road Equipment Emissions Calculated Using the TexN Emission Model
All off-road emissions except for emissions from locomotives and drilling equipment are
estimated in the TexN model; TexN model sources taken together represent 74% of off-road
NOx emissions and 98% of off-road VOC emissions in Hood County.
The TexN model includes input data that has been updated to more accurately reflect Texas
specific off-road operations as well as NONROAD default data. There have been a number of
emission inventory improvements in TexN which are typically made on a category-by-category
basis and consist of updates to the statewide equipment population, spatial allocation of
population, temporal allocations, and/or annual hours of use estimates.
For those equipment types for which NONROAD default data is used there is considerable
uncertainty in emissions that are calculated with TexN. NONROAD model default base year
statewide population estimates were developed based on nationwide population estimates
allocated to the state level using spatial surrogates. National equipment populations were
developed from calendar year 1996 to 2000 base year data. Growth rate estimates used to
project population to past and future years were estimated for most source categories based
on population trends taken from EPA’s analysis of 1989 to 1996 nationwide population data
(exceptions are off-road motorcycles, ATVs and snowmobiles) (EPA, 2004); a notable exception
is construction equipment population growth rates which were estimated based on Texasspecific data in (ERG, 2014).
The TexN model includes Texas-specific non-default estimates of growth rates for most diesel
construction equipment types. TexN also includes Texas-specific temporal allocations which
may differ from NONROAD region-specific default temporal allocations. Because of the
distributed nature of off-road equipment across residential, commercial and industrial sectors,
updating NONROAD model inputs can be resource-intensive. The TCEQ has funded a series of
studies that have developed detailed Texas-specific data for use in TexN as described in ERG
(2008b) and ERG (2014). Table 4 below summarizes data sources used in the TexN model for
the Hood County area. Below, we discuss source categories that make the largest contributions
to the Hood County area off-road NOx emission inventory and describe more detailed nondefault data for Hood County that were available within TexN.
Table 4. Non-default data used in the TexN model for the Hood County area (ERG, 2008b).
Statewide
Spatial Allocation
Temporal
Annual Hours
Equipment Type
Population
(of population)
Allocation
of Use
Construction and
Mining4
Non-default1
Non-default1
Non-default1 Non-default1
Agricultural4
Non-default
Non-default
Non-default
Non-default
D
D
D
D
Industrial
D
D
D
D
Commercial
D
Lawn and Garden
Non-default2
Non-default2
Non-default2
13
March 2015
Statewide
Equipment Type
Population
D
Logging
Pleasure Craft
Non-default
D
Recreational
D
Railroad
3
Airport Ground
D
NONROAD model default data used.
Support
1
Spatial Allocation
(of population)
Temporal
Allocation
Annual Hours
of Use
D
D
D
Non-default
D
D
D
D
D
D
D
D
D
D
D
Local data limited to diesel powered construction equipment greater than 25 horsepower.
Local data limited to commercial lawn and garden equipment.
3
No population estimates provided in TexN.
4
Additional information provided below for this category because it is a major off-road NOx emission source.
2
Agricultural Equipment
In a 2009 study (Thesing, 2009) data on agricultural equipment use were gathered from Texas
farming operation owners via a telephone survey; these data were used to improve
representation of equipment populations, annual hours of use, and seasonal, weekly and
diurnal activity profiles for agricultural equipment within TexN. Because of the Texas-specific
update to agricultural data within TexN that includes DFW-specific survey data, improvements
to this category are not recommended.
Construction and Mining Equipment
TexN diesel construction equipment data for the entire state of Texas were updated based on
Baker and Preusse (2009) which revised equipment profiles based on surveys of equipment
operators. Updated data included information on equipment populations by county,
horsepower (hp) distributions and hours per year of operation based on information gathered
for the DFW nine county area (not including Hood County). While use of Hood County
equipment profiles is ideal, use of DFW nine county area based profiles is reasonable based on
expected overlap in equipment fleets in the DFW nine county area and Hood County.
2.2.2 Off-Road Equipment Emissions Calculated Outside of the TexN Emission Model
Drilling. Drilling equipment emissions include emissions from drilling rigs at oil and gas wells.
Drilling rigs are most commonly powered by one or more diesel-fired compression-ignition
engines that power the rig’s draw works, mud pump and generators. Drilling emissions were
estimated by TCEQ based on ERG (2010a) methodology and 2012 drilling activity obtained from
the Texas Railroad Commission (TRC) (TCEQ, 2014b). Baker Hughes6 estimates of annual
average rig count in the Barnett Shale were 72 rigs in 2011 compared to 47 rigs in 2012 (a 35%
decrease). The 35% decrease in Barnett Shale rig count agrees very closely with the decrease in
drilling NOx emissions from the 2011 NEI to the 2012 TCEQ emission inventory of 39%.
6
http://www.bakerhughes.com/rig-count
14
March 2015
Locomotives. Line-haul locomotive emissions are reasonable based on expected and actual
close agreement between the 2011 NEI and 2012 TCEQ emission inventory. Emissions
associated with switching locomotive activity at the Cresson rail yard, however, are not
included in the TCEQ 2012 inventory or the 2011 NEI based on omission of any emissions from
the switching locomotive source category classification code (SCC 2285002010) in Hood County
in both of these emission inventories. “Switching” is the process of sorting and re-combining
rolling stock at a rail yard. Locomotive emission estimates were recently updated from the
emissions presented in ERG (2010b), however, documentation is not yet available to
understand how switching locomotive emissions were estimated and/or why the Cresson rail
yard is not included.
15
March 2015
3.0 AREA SOURCE EMISSIONS REVIEW
The area source inventory treats in aggregate all stationary sources that have emissions below
the point source threshold. These are sources that may be spread out geographically and are
small individually, but taken together, may constitute a sizeable amount of emissions. Examples
of area sources include dry cleaners, residential wood heating, auto body painting, fires, oil and
gas wells and consumer solvent use. These emissions are typically estimated and reported as
county totals and allocated to a finer geographic scale using a surrogate such as population
distribution. For example, if a certain amount of VOC emissions are allocated to dry cleaners in
a given county most of those emissions would be allocated to the locations within the county
that have the highest population density.
3.1 Overview of emissions inventory
ENVIRON obtained the 2012 oil and gas and non-oil and gas area source emission inventories
for Hood County from the TCEQ ftp site (TCEQ, 2014a). For non-oil and gas area sources,
emissions were available for a typical weekday, Saturday, and Sunday. Average day emissions
were estimated by source classification code (SCC) as: (weekday emissions x 5+ Saturday
emissions + Sunday emissions) / 7. Hood County area source emissions by county and source
category are presented in detail in Appendix A.
The area source sector is made up of various types of stationary sources that fall below point
source permitting thresholds. Typically, area source emissions are estimated based on EPA AP42 methods7. For certain area source categories such as consumer products, human population
or a related surrogate such as housing units is the typical emissions activity surrogate; these
emission sources are of smaller magnitude than oil and gas sources in Hood County. Human
population is provided for reference in Table 3-1. From 2006 to 2012, human population in
Hood County increased by 8%.
Table 3-1. Population changes in Hood County between 2006 and 2015. Data source:
http://www.dshs.state.tx.us/chs/popdat/default.shtm
Year
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
7
Human
Population
49,058
50,214
50,688
51,381
51,182
52,105
53,105
54,099
55,084
56,112
Annual
Growth
3%
2%
1%
1%
0%
2%
2%
2%
2%
2%
http://www.epa.gov/ttn/chief/ap42/
16
March 2015
Of particular importance for Hood County are area source oil and gas emissions which are
significant sources of VOC and NOx emissions due to the number of oil and gas wells in Hood
County. As shown in Figure 3-1, there are hundreds of oil and gas wells in Hood County8. Close
to 100% of oil and gas wells in Hood County are gas wells. TRC data for calendar year 2014
indicates the presence of only one oil well in Hood County which produced 152 barrels (bbl) of
oil and 3,050 thousand cubic feet (MCF) of gas. Close to 100% of Hood County wells produce
gaseous and liquid hydrocarbons from the Barnett Shale formation. From 2004 to 2007 there
were favorable natural gas prices for development and the number of gas wells in Hood County
increased steadily. From 2007 to 2009 the number of gas wells in Hood County increased
sharply; during 2008 natural gas prices reached their peak then dipped sharply from late 2008.
From 2009 to 2010, as natural gas prices remained low, there was a slower pace of increase in
the number of gas wells. The number of gas wells has been relatively constant from 2010 to
2014 during which natural gas prices remained significantly lower than the 2008 peak price.
Increases in well count since 2004 in Hood County are due to development of the Barnett Shale
oil and gas play. As well count increased from 2004, gas production and condensate production
also increased sharply; gas production reached a maximum in 2009 and condensate production
reached a maximum in 2008 after which both oil and gas production declined steadily to 2014.
Oil and gas production declines are due to well decline (i.e. the tapering off of hydrocarbon
production as a well ages) outpacing production from new oil and gas development in Hood
County. Figure 3-2 shows a similar trend of increases in Barnett Shale-wide gas production to
2012 with a tapering off of production from 2012 to 2014. Hood County has gas production
trends that show both delayed increases in gas production and earlier declines in gas
production relative to the Barnett Shale-wide trends which indicates that Hood County was
both developed later and the pace of development slowed earlier than in other areas of the
Barnett Shale. The pace of Hood County development relative to the entire Barnett Shale
reflects Hood County’s location outside of the “sweet spot” of the Barnett Shale Play (Figure
3-3).
8
http://www.rrc.state.tx.us/
17
March 2015
Figure 3-1. 2000-2014 oil and gas production (left) and well count (right) totals for Hood
County based on TRC oil and gas activity data. (Well counts are as of beginning of February
for each year).
Figure 3-2. 2000-2014 oil and gas production from the Barnett Shale.
18
March 2015
Figure 3-3. Natural gas productivity within the Barnett Shale. Figure from the Texas Bureau of
Economic Geology: http://www.utexas.edu/news/files/Productivity-Tiers-2.jpg.
Table 3-2 compares 2012 Hood County-wide oil and gas vs. non-oil and gas area source
emissions of NOx and VOC, and Figure 3-4 and Figure 3-5 show 2012 area source emission
contributions by source category in Hood County. Oil and gas area source emissions are the
highest contributor accounting for 96% and 70% of NOx and VOC emissions, respectively. Fuel
combustion accounts for 4% of NOx emissions, while the 30% of VOC emissions not accounted
for by oil and gas sources are distributed across a number of source categories including
contributions of 13% from gasoline distribution and 8% from consumer products.
Table 3-2.
Hood County 2012 area source emissions.
Source
Non-Oil and Gas
Oil and Gas
Total Area
2012 Emissions
NOx
VOC
0.13
2.17
2.86
5.11
2.99
7.28
19
March 2015
Figure 3-4. Hood County 2012 area source NOx emissions emission by source category.
Figure 3-5. Hood County 2012 area source VOC emissions emission by source category.
20
March 2015
ENVIRON compared 2012 area source emissions by source category to the 2011 NEI as a gross
check on the magnitude of the emissions in the 2012 TCEQ inventory. Table 3-3 shows changes
in Hood County inventory from the 2011 NEI to 2012 TCEQ inventory. Differences between the
two inventories are quite large for oil and gas area source NOx emissions, but are similar
otherwise. Close to 100% of the difference in NOx emissions between the two inventories is
due to differences in compressor engine emission estimates. As part of the 2011 NEI
development effort EPA compiled the Oil and Gas Emission Estimation Tool9 which estimates oil
and gas emissions based on oil and gas activity inputs and equipment configuration data by
county. It is likely that 2011 NEI oil and gas area source emissions differ considerably from TCEQ
2012 inventory emission estimates due to lack of local data in the 2011 NEI. The TCEQ 2012
estimate of compressor engine emissions is based on local data.
Table 3-3.
2011 and 2012 area source emissions comparison.
Source
Non-Oil and Gas
Oil and Gas
Total Area
2011 NEI Emissions
NOx
VOC
0.11
2.02
0.01
5.51
0.12
7.53
2012 Emissions
NOx
VOC
0.13
2.17
2.86
5.11
2.99
7.28
Oil and gas emission contributions to area source emissions by source category are shown in
Figure 3-6 and Figure 3-7. The largest source of oil and gas NOx emissions is compressor
engines (95%) while fracturing engines comprise 5% of NOx emissions. The largest sources of
VOC emissions are condensate tanks (54%), pneumatic devices (14%) and pneumatic pumps
(11%).
9
ftp://ftp.epa.gov/EmisInventory/2011nei/doc/Tool_and_Report112614.zip
21
March 2015
Figure 3-6. Hood County 2012 oil and gas source NOx emissions by source category.
Figure 3-7. Hood County 2012 oil and gas source VOC emissions by source category.
22
March 2015
3.2 Analysis
The emissions analysis below focuses on those categories responsible for the preponderance of
Hood County area source NOx and/or VOC emissions and for which emission updates could
have significant effects on the emission inventory.
3.2.1 Oil and Gas Emissions
TCEQ (2014b) provides a description of the basis of the oil and gas area source emissions
development. Oil and gas emission inventory estimates are primarily based on the ERG (2010a)
study with updates to emission factors and equipment profiles for a number of source
categories as listed below. ERG (2010a) emission estimation methodology and inputs are based
on the BSASI for a number of sources. In developing the BSASI, the TCEQ used its regulatory
authority to compel survey participation by all companies with production or transmission of
Barnett Shale oil or gas; because participation was compulsory, TCEQ received a very high
response rate (98%). Included in the BSASI data request was the request for provision of 2009
emissions for NOx, VOC and hazardous air pollutant (HAP) emissions. The survey data allowed
for improvement of the Barnett Shale oil and gas emission inventory.
Condensate tank emission estimates were based on a methodology described in ERG (2012).
Condensate tank emission rates are typically estimated using software such as the E&P Tank
model or the HYSYS process simulator; condensate production is multiplied by condensate tank
emission rates to estimate county-level emission estimates; flaring or vapor recovery may be
used to control condensate tank VOC emissions. Uncontrolled VOC emission factors for the
Barnett Shale (9.76 pounds VOC per barrel of condensate) including Hood County were
estimated based on data gathered as part of the BSASI10. A control factor of 11.8%, estimated
based on the BSASI, accounts for the fraction of emissions that are controlled and estimated
control efficiency. The BSASI was compiled based on a compulsory request by TCEQ to Barnett
Shale operators to provide specific oil and gas emissions data, including data for condensate
tanks, and obtained a very high response rate (greater than 90% of all condensate production
reported). Since the TCEQ 2012 emissions are based on emission factors estimated from
surveys of Barnett Shale condensate tanks they can be considered reasonably representative of
Hood County condensate tank emissions. The EPA New Source Performance Standard Subpart
OOOO requires controls on tanks emitting more than six tons of VOC per year after August 23,
2011. In 2012 the effect on emissions is expected to be small as it only applies to wells drilled in
late 2011 and 2012. However, for future year emission inventories the effect of Subpart OOOO
on emissions will need to be accounted for.
Heater emission estimates were developed based on equipment profiles and emission factors
for the Arch Bend-Fort Worth region developed in ERG (2013). The Hood County heater profiles
10
“Barnett Shale Area Special Inventory, Phase One”, TCEQ, 2009,
http://www.tceq.texas.gov/assets/public/implementation/air/ie/pseiforms/Barnett%20Shale%20Area%20Special%20
Inventory.pdf, “Barnett Shale Phase Two Special Inventory Data”, TCEQ,
http://www.tceq.texas.gov/assets/public/implementation/air/ie/pseiforms/summarydatainfo.pdf
23
March 2015
used to estimate 2012 emissions assumed the presence of 0.15 heaters per well. This was
based on responses from operators representing 5% of liquid hydrocarbon production in the
Fort Worth area. ERG (2013) noted the higher frequency of heaters in the 2013 study relative to
the 2009 BSASI and suggested that this could be due to the fact that the BSASI threshold for
response was any source emitting more than 1 ton per year of NOx or 5 tons per year of NOx
site-wide; some smaller heaters may not have been covered in the BSASI.
Pneumatic devices emissions were estimated based on survey data collected as part of the
BSASI study. EPA New Source Performance Standard Subpart OOOO requires use of low-bleed
pneumatic devices (i.e. pneumatic devices that are rated at 6 standard cubic-feet of gas per
hour (scf/hr) or lower) from August 23, 2011 at new or modified wells. The 2012 pneumatic
device emissions do not reflect EPA New Source Performance Standard Subpart OOOO controls.
Since Subpart OOOO only applies to new or modified wells installed from August 23, 2011, the
effect of Subpart OOOO is expected to be small in the 2012 emission inventory. However,
future year inventories will need to consider the effect Subpart OOOO on pneumatic device
emissions.
Pneumatic pump emissions were estimated based on EPA oil and gas emissions tool equipment
profiles and operational characteristics. Pneumatic pump emissions are not currently based on
data specific to the Barnett Shale and should be considered for update.
Compressor engine emissions were estimated based on BSASI data. TCEQ (2014b) described
this as follows:
TCEQ conducted the Barnett Shale Special Inventory in 2011, obtaining data from over
8,000 sites that operated in the Barnett Shale in 2009, including information from over
1,850 compressor engines. This compressor engine data was combined with control
requirements from the TCEQ Chapter 117 NOx rules to develop updated compressor
engine profiles and emission factors for the DFW non-attainment counties, the Barnett
Shale attainment counties, and the East Texas area.
Hood County is not subject to TCEQ Chapter 117 NOx rules. Hood County compressor engine
emissions are based on local survey data compiled as part of the BSASI; they are expected to be
reasonably representative of Hood County emissions.
Table 3-4 summarizes the methodology used to compile oil and gas emissions for each oil and
gas source category as presented in ERG (2010a) and based on communication with TCEQ staff
(TCEQ, 2014b). Source categories not based on Barnett Shale survey data are recommended for
update except for oil related source categories which are expected to have very small emissions
in Hood County and are not recommended for update.
24
March 2015
Table 3-4.
Oil and gas emissions methods summary by source category.
Source Category
Artificial Lift
(Pumpjack)
Engines
Brief description of how unit-level emissions were estimated*
Engines were assumed to operate at any oil well greater than one
year old. Statewide assumptions were implemented as follows:
70% of pumpjack engines are electric, uncontrolled emissions
factors were applied (assumed that no engines meet NSPS
standards), horsepower, load factor, and annual usage were
estimated for a typical engine.
As described above, Hood County compressor engine emissions
are based on local data collected as part of the BSASI.
Recommended for Update?
No, crude oil production is
too small to warrant
additional consideration.
Dehydrators
Emissions per unit of gas production were estimated based on
central facility dehydrator GLYCalc reports and controls. ERG
(2010a) indicates that these estimates may be biased low
because application of dehydrator controls at well sites may be
different than at central facilities.
Fugitives
Components
The number of devices per well were taken from Bar-Ilan et al.
(2008) for the Fort Worth Basin. AP-42 emission rates per device
were applied. Bar-Ilan et al. (2008) did not include Barnett Shalespecific data for component counts.
Emissions were estimated based on TERC (2009).
Yes, basis of current area
source emissions is data
collected from larger facility
that meets emissions
criteria for a point source;
current emissions may be
biased low.
Yes, fugitive device counts
are not based on Barnett
Shale-specific data.
Compressor
Engines
Crude Oil
Storage Tanks
Condensate
Storage Tanks
Condensate tank emissions were estimated based on emission
factor and control information from the BSASI as described in
ERG (2012) applied to TRC estimates of condensate production.
Heaters
Heater emissions were estimated based on emission factor and
equipment configuration estimates in ERG (2013) and TRC
estimates of well count.
Tank
Truck/Railcar
Loading of Crude
Oil and
Condensate
Well Venting
(blowdowns)
Emission rates per barrel loaded were estimated using AP-42
methodology. Assumed that all crude oil and condensate
production in each county is loaded once.
Well
Completions
Pneumatic
Pumps
Average blowdown frequency per well and vented volume was
taken from Bar-Ilan et al. (2008) for the Fort Worth Basin based
on survey data collected for the Fort Worth Basin.
Average completion vented volume per well and prevalence of
flaring and green completion control were taken from Bar-Ilan et
al. (2008) for the Fort Worth Basin. EPA Subpart OOOO regulation
requires VOC emissions from completions at hydraulically
fractured wells drilled after August 23, 2011 to be controlled by
flare; for wells drilled after January 1, 2015, control by green
completion techniques is required.
As described above, pneumatic pump emissions were estimated
based on EPA oil and gas emissions tool equipment profiles and
25
No
No, emissions from crude
oil production are too small
to warrant additional
consideration.
No
Yes, low survey response
rates may lead to
inaccurate estimates of
heater configuration and
prevalence.
No
No
Yes, well completion
emission estimates do not
include the effects of EPA
Subpart OOOO regulations.
Yes
March 2015
Source Category
Pneumatic
Devices
Produced Water
Brief description of how unit-level emissions were estimated*
operational characteristics. Pneumatic pump emissions are not
currently based on data specific to the Barnett Shale.
As described above, pneumatic devices emissions were estimated
based on survey data collected as part of the BSASI study.
Average emission factors from produced water were estimated
from ENVIRON (2010a).
Recommended for Update?
No
No
* Oil and gas activity (e.g. number of wells, gas production, oil production) was taken from Texas Railroad Commission (TRC)
databases and applied to unit-level estimates to develop emission inventory estimates. For example, heater emissions were
estimated by multiplying the unit-level estimate of average heater emissions per well by the number of oil and gas wells in a
given county.
As described in Table 3-4, there are oil and gas source categories for which emission estimates
rely on Barnett Shale specific data and source categories for which emission estimates rely on
data that is outdated and/or not specific to the Barnett Shale. Compressor engines, the largest
source of oil and gas NOx emissions Hood County, and a number of other categories rely on
data collected for the Barnett Shale as part of the BSASI Study.
Emissions from oil and gas production (with close to 100% of that production from the Barnett
Shale) are a large component of the NOx emission inventory for Hood County; this is expected
given that, in 2012, there were approximately 800 wells producing oil and gas in Hood County.
Accurate characterization of oil and gas emissions is a high priority. Updating Hood County
heaters, pneumatic pumps, fugitive devices, dehydrators and well completions emissions is
recommended.
3.2.2 Fuel Combustion Emissions
Area source fuel combustion estimates are based on state-level fuel consumption activity data
which typically includes consumption from point and area sources and is obtained from the
Energy Information Administration (EIA). Area source-specific fuel consumption is estimated by
allocating state-level consumption estimates to the county-level and reconciling county-level
fuel consumption estimates with point source fuel consumption. Because the reconciliation
step requires compiling both fuel consumption estimates and reconciling those fuel
consumption estimates against point source fuel consumption, a separate study would need to
be performed to confirm the accuracy of the TCEQ emission inventory estimates for area
source fuel combustion. Given that these emissions are a relatively small component of the
Hood County inventory (<4% of total NOx emissions), such a study is not recommended.
3.2.3 Gasoline Distribution Emissions
Gasoline distribution emissions account for about 13% of 2012 anthropogenic area source VOC
emissions. Gasoline distribution emissions are associated with transport and delivery of
gasoline and include the following types of emissions: Stage I (transfer from tanker truck to
service station tanks), Stage II (vehicle refueling), storage tank breathing and evaporative
emissions associated with truck transport. A study of gasoline distribution emissions by ERG
26
March 2015
(ERG, 2008a) commissioned by TCEQ is the source of gasoline distribution emissions in the 2012
TCEQ emission inventory.
The ERG (2008a) study surveyed 3,000 service stations in Texas, eight of which were in Hood
County, to obtain station specific data for gasoline tank throughput. Based on information
provided by survey respondents (23.4% response rate) about tank throughput and tank volume
data available from TCEQ underground storage tank records, a model was developed that
estimated annual throughput of a given gasoline storage tank based on the storage tank’s
capacity by grade of fuel.
Emission rates in ERG (2008a) for each process were estimated according to standard
methodology for each source as described below. Uncontrolled Stage I and Stage II emission
rates were assumed for Hood County.

Stage II (refueling): Emission rates estimated based on MOBILE6 model. It is noted that
MOBILE6 is no longer the preferred model for estimating Stage II emission rates; the
current preferred model to estimate Stage II emission rates is the MOVES model.

Stage I (transfer from tanker truck to service station tanks): AP-42, section 5.2 emission
rates were applied for submerged filling.

Storage tank breathing: AP-42, section 5.2 emission rates.

Truck transport: AP-42, section 5.2 emission rates.
ENVIRON compared total estimated throughput for Texas in ERG (2008a) with EIA data and
found significant differences in gasoline throughput estimates (see Table 3-5).
Table 3-5.
Year
CY2007
CY2007
CY2008
CY2012
1
Texas statewide annual gasoline consumption.
Source
ERG (2008b)
Energy
Information
1
Administration
Annual Gasoline
Consumption
(billion gallons)
17.8
12.2
12.1
12.7
Texas State Profile and Energy Estimates, http://www.eia.gov/state/?sid=tx
Additional data could be used to evaluate whether annual gasoline throughput estimates in
Hood County are in reasonable agreement with records of annual gasoline consumption which
should be available from a state or local agency based on sales tax records receipts. However,
given the magnitude of emissions from gasoline distribution (0.93 tpd in 2012), even a decrease
of 50% in these emissions would only represent a decrease of 5% in anthropogenic VOC
emissions. Update of this source category is a low priority as this update will only result in
changes to VOC emissions.
27
March 2015
4.0 POINT SOURCE EMISSIONS REVIEW
Point sources are large stationary emissions sources that exceed a specified emissions
threshold. Point source emissions are frequently but not always released through an exhaust
stack. In non-attainment areas, the TCEQ defines a point source to be any industrial,
commercial or institutional source that emits actual levels of criteria pollutants at or above the
following amounts: 10 tons per year (tpy) of VOC; 25 tpy of NOx; or 100 tpy of any of the other
criteria pollutants including CO, SO2, PM10, or lead. In attainment areas of the state such as
Hood County any facility that emits a minimum of 100 tpy of any criteria pollutant must submit
a point source emissions inventory to the TCEQ. Each point source has a well-defined location
(latitude and longitude) as well as ancillary information known as stack parameters that
indicate the height at which emissions are released, the diameter of the emitting stack, and
other factors. As with all other TCEQ ozone modeling emission inventories the 2012 point
source inventory contains air emissions of the following ozone precursors: NOx, VOC and CO.
4.1 2012 Point Source Emissions
The TCEQ developed statewide 2012 emissions from data from the TCEQ’s State of Texas Air
Reporting System (STARS) and the EPA’s Acid Rain Program. While there is currently no publicly
available documentation specific to this emission inventory, documentation is expected to be
released by TCEQ in 2015.
The STARS database is administered by the TCEQ. Each year the TCEQ sends questionnaires to
all facilities that meet reporting requirements of 30 Texas Administrative Code (TAC) §101.10.
The TCEQ collects point source emissions data as well as industrial process operating data. For
all sources except electric generating units (EGUs), the TCEQ uses this data to compile ozone
season day (OSD) emissions. The OSD emissions represent average daily emissions during the
summer when ambient ozone in Texas is highest.
The EPA requires all existing utility units serving generators with an output capacity of greater
than 25 megawatts (MW) and all new utility units to continuously measure and record their
emissions of SO2, NOx and CO2 as well as other quantities such as heat input of fuels. This is
accomplished through in-stack monitoring using a Continuous Emissions Monitor (CEM). All
sources must submit hourly emissions data to the EPA’s Clean Air Markets Division (CAMD) Acid
Rain Program Database (ARPDB) on a quarterly basis.
Typically, hourly EGU emissions are used in ozone modeling to provide the most accurate
possible simulation of emissions as well as transport and fate of EGU emissions, however, TCEQ
OSD average emissions were generated for EGUs from the hourly data for the emissions
analysis presented here.
4.1.1 Emission Summary
The TCEQ 2012 point source emission inventory is summarized below in several different ways
to establish (1) the geographical distribution of point source emissions, (2) the relative
importance of point source emissions by industry and (3) the relative importance of emissions
28
March 2015
sources by the mass of pollutants emitted. Appendix B includes a table of TCEQ estimates of
point source emissions by facility.
Figure 1-1 and Figure 1-2 in Section 1.2 above show emissions by source category in Hood
County. Point sources are one of the three largest contributors to NOx emissions accounting for
29% of the total emissions in 2012. Point source emissions account for minor contributions to
total VOC emissions.
Figure 4-1 shows the location of Hood County point sources in the 2012 TCEQ emission
inventory. Source locations were taken directly from modeling files. The size of the facility
location circle represents the magnitude of facility-level NOx emissions.
Figure 4-1. Map showing location of Hood County point sources in the TCEQ 2012 NOx
emission inventory (facility name labels not provided for facilities emitting 0.03 tpd NOx or
less).
Table 4-1 shows Hood County point sources emissions by facility in the 2012 emission
inventory. The Wolf Hollow I power plant is by far the largest NOx emissions source accounting
29
March 2015
for 52% of point source NOx emissions; two gas processing plants, Corvette and Cowtown are
the next largest NOx emission sources accounting for 12% and 9% of NOx emissions,
respectively. Three gas processing plants are the largest VOC sources; the Cowtown Gas
Processing Plant, Tolar Gas Plant, and Corvette Gas Processing Plant each accounting for 27%,
25% and 14% of VOC emissions, respectively.
Table 4-1.
Top emitting NOx and VOC point sources in Hood County.
Facility
Wolf Hollow I
2012 NOx
Percent of
Hood
County
tons/
point
day
emissions
Facility
Cowtown Gas Processing
Plant
2012 VOC
Percent of
Hood
County
tons/
point
day
emissions
0.27
27%
0.25
25%
0.14
14%
0.06
0.06
0.04
0.04
6%
6%
4%
4%
DeCordova Power Plant
0.03
3%
2%
Wolf Hollow I
0.01
1%
Randle A Unit 8H 9H
0.01
1%
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
<0.01
1%
1%
1%
1%
1%
1%
1%
1%
1%
<1%
<0.01
<1%
1.7
52%
0.4
12%
0.3
9%
0.2
0.2
0.1
0.1
6%
5%
4%
3%
Corvette Gas Processing
Plant
Vermont Hares Ear C Pad
Taylor Swd Red Dragon
Sherry P Deborah Lou Ctb
Cresson Compressor Station
0.1
3%
0.1
Plant
Plant
Tolar Gas Plant
Helton Pad
Electric Power Generation
(Tenaska Gateway Partners)
Black Ranch A3H A4H A6H
Wellborn Simon Common
Bat
Boggs Unit 3H 4H Taylor U
Randle B Unit 20H 21H
Randle A Unit 8H 9H
Randle A Unit 13H
West Granbury Unit 1H 2H
Randle A Unit 10H 11H
Kidd C Unit 5H 6H
Brock Unit 4
0.1
2%
0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
2%
1%
<0.5%
<0.5%
<0.5%
<0.5%
<0.5%
<0.5%
<0.5%
<0.5%
DeCordova Compressor
<0.1
<0.5%
Tolar Gas Plant
Kidd C Unit 5H 6H
Randle A Unit 13H
Brock Unit 4
Helton Pad
Bat
Next we examine the breakdown of point source emissions by type of emitting facility. Facilities
are categorized by type by their Standard Industrial Classification (SIC) code which is a four-digit
numerical code assigned by the U.S. Securities and Exchange Commission that is unique to each
type of industry. Table 4-2 shows emissions by SIC code. The Electric Services sector, which
encompasses EGUs, transmission and distribution, is the largest source of point source NOx
emissions in Hood County, accounting for 58% of NOx emissions; the Crude Petroleum and
30
March 2015
Natural Gas sector accounts for 25% of point source NOx emissions. The largest contributor to
point source VOC emissions is the Crude Petroleum and Natural Gas sector (58%); the Natural
Gas Transmission and the Natural Gas Liquids sectors account for 25% and 14% of point source
VOC emissions, respectively.
Table 4-2.
SIC
4911
1311
1321
4922
Totals
Hood County point source emissions by industrial sector.
OSD Emissions (tons/day)
NOx
VOC
CO
1.9
<0.1
5.0
0.8
0.6
0.5
0.4
0.1
<0.1
0.2
0.3
0.1
3.3
1.0
5.7
SIC Description
Electric Services
Crude Petroleum and Natural Gas
Natural Gas Liquids
Natural Gas Transmission
Percent of OSD Emissions
NOx
VOC
CO
58%
3%
88%
25%
58%
9%
12%
14%
1%
5%
25%
2%
100%
100%
100%
4.2 Point Source Emission Comparison to NEI
The 2012 TCEQ emission inventory is compared to the 2011 NEI below to analyze recent trends
in Hood County point source emissions.
Figure 4-2 shows Hood County point source emissions totals for NOx and VOC from the 2012
TCEQ emission inventory and 2011 NEI. This comparison is made as a gross check on the
magnitude of the TCEQ 2012 emission estimates. Compared to the 2011 NEI estimates TCEQ
2012 point source NOx and VOC emissions are 12% and 13% larger. Differences between the
2011 NEI and the 2012 TCEQ inventory are primarily due to differences in Wolf Hollow I
emissions. Since Wolf Hollow I is a “peaking unit”, that is a unit that usually operates only when
demand for electrical power on the grid approaches a peak, it is expected to have more activity
and emissions during an average OSD in the summer season in the TCEQ 2012 inventory
compared to annual average Wolf Hollow emissions estimates in the 2011 NEI.
Figure 4-2. Hood County ozone season day point source emissions from the 2011 NEI and
2012 TCEQ inventories.
31
March 2015
Table 4-3 shows the 2011 NEI and 2012 TCEQ emissions of NOx and VOC, respectively, by
facility for all facilities in the TCEQ 2012 emission inventory; additional sources in the 2011 NEI
are described below. The largest change in NOx emissions from 2011 to 2012 is the 0.7 tpd
increase Wolf Hollow I emissions. VOC emission from the largest three VOC sources, Cowtown
Gas Processing Plant, Tolar Gas Plant, and Corvette Gas Processing Plant increased by 0.10 tpd,
0.11 tpd and 0.02 tpd, respectively.
Table 4-3. 2011 NEI and 2012 TCEQ NOx ozone season day point source emissions by year
by facility.
Facility
SIC
NOx Emissions
(tons per ozone
season day)
2011
2012
NEI
TCEQ
Facility
SIC
VOC Emissions
(tons per ozone
season day)
2011
2012
NEI
TCEQ
4911
1.0
1.7
Plant
1311
0.17
0.27
1321
0.4
0.4
Tolar Gas Plant
4922
0.14
0.25
1311
<0.1
0.3
1321
0.12
0.14
4911
4922
1311
1311
1311
1311
0.4
0.2
0.1
<0.1
0.1
0.2
0.2
0.2
0.1
0.1
0.1
0.1
Plant
Helton Pad
1311
1311
1311
1311
4911
1311
0.04
0.05
0.03
0.05
0.02
0.01
0.06
0.06
0.04
0.04
0.03
0.01
1311
0.2
0.1
1311
0.02
0.01
1311
<0.1
0.1
Randle A Unit 8H 9H
1311
0.03
0.01
1311
1311
1311
1311
1311
1311
1311
1311
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
1311
1311
1311
1311
1311
1311
4911
1311
0.01
0.01
0.03
0.02
0.02
0.02
<0.01
0.02
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Brock Unit 4
1311
<0.1
<0.1
1311
0.01
<0.01
1311
<0.1
<0.1
Brock Unit 4
Randle A Unit 13H
Kidd C Unit 5H 6H
Wolf Hollow I
Bat
1311
<0.01
<0.01
Wolf Hollow I
Plant
Plant
Tolar Gas Plant
Helton Pad
Bat
Cresson Compressor
Station
Randle A Unit 8H 9H
Randle A Unit 13H
Kidd C Unit 5H 6H
Table 4-4 summarizes the number of facilities by SIC in the 2011 and 2012 inventories while
Table 4-5 shows emissions from sources that were not included in both inventories. The
32
March 2015
inventories are, to a large extent, consistent with each other in terms of the facilities included
except for airports and airfields (SIC 4581 and 4700) which are included only in the 2011 NEI. Of
all sources that were not consistently identified in all three years none of these sources emitted
over 0.06 tpd of NOx or 0.02 tpd of VOC (see Table 4-5).
Table 4-4. Number of facilities by SIC in the 2011 NEI and 2012 TCEQ point source emission
inventory.
SIC
SIC Description
1311
4911
4922
1321
4581
4700
Totals
Crude Petroleum and Natural Gas
Electric Services
Natural Gas Transmission
Natural Gas Liquids
Airports, Flying Fields & Airport Terminal Services
Transportation Services
Number of Facilities
2012
2011
TCEQ
NEI
17
21
2
2
1
1
1
1
0
6
0
1
21
32
Table 4-5. NOx and VOC emissions for facilities that did not report emissions in both years,
2011 and 2012.
Facility
SIC
Black Ranch 12H 14H
Black Ranch 8H 10H
Granbury Muni
(air strip/ airfield)
KVUE-TV
Maberry Common Battery A
Morrison Unit 1H
Nassau Bay
Parker
Pecan Plantation
Shelton Pvt
The Landings
1311
1311
2012 EI
NOX
VOC
-
2011 NEI
NOX
VOC
0.05
0.01
0.05
0.01
4700
-
-
<0.01
<0.01
4581
-
-
<0.01
<0.01
1311
1311
-
-
0.06
<0.01
0.02
<0.01
4581
-
-
<0.01
<0.01
4581
-
-
<0.01
<0.01
4581
-
-
<0.01
<0.01
4581
-
-
<0.01
<0.01
4581
-
-
<0.01
<0.01
4.3 Newly Permitted Power Plant Units
Comparing potential emissions from proposed new sources to actual emissions from existing
sources is difficult because the information available is fundamentally different. Actual
33
March 2015
emissions for existing sources are estimated from historical records of how those sources
operated over specific time periods. For proposed new sources permit applications generally
provide estimates of maximum allowable emissions under specific operating conditions. In this
section we compare emission estimates for proposed and existing sources to place potential
new emissions in context with existing emissions. These comparisons are uncertain and may
tend to over-state the importance of emissions from proposed new sources.
4.3.1 DeCordova Power Plant Expansion
The DeCordova Power Plant is located near Granbury and is owned and operated by Luminant.
The facility has an operating capacity of 260 MW11. In October 2014 TCEQ approved a permit
revision to the DeCordova II Power Company Steam Electric Station authorizing construction
and operation of two new natural gas-fueled combustion turbine generators (CTGs) at the
DeCordova Power Plant; these units would replace the existing 860 MW Unit 1 steam boiler and
are expected to operate as peaking units in simple cycle mode. The two units together will have
a generation capability of 460 MW. NOx control measures include the use of dry low-NOx
(DLN) burners. In a DLN burner, air and fuel are pre-mixed to reduce formation of thermal NOx
without need for injection of water or steam. DLN burners are considered to be the Best
Available Control Technology (BACT) for peaking turbines in Texas. To minimize NOx emissions
and comply with BACT the turbines are limited to 100 hours peak firing during any rolling 12
month period. Selective Catalytic Reduction (SCR) technology which is proven also to achieve
large emissions reductions from electric generators was not considered due to limits on
maximum heat input for the CTGs and cost.
It is important to note that while these facilities have been permitted there is a chance that
they will not be constructed. In January 2015 Luminant spokesman Brad Watson was quoted as
stating “Luminant has made no final decision to build these units. The company took these
steps to position it to quickly add new generation to the market when price conditions improve
to a level that incents new generation”.12
Table 4-6 shows NOx hourly maximum allowable emission rates for the two configuration
options with estimated daily maximum allowable emission rates. The allowable hourly
emissions were multiplied by 24 hours per day to estimate allowable daily emissions from these
newly permitted and yet to be constructed units. Estimated allowable daily emissions represent
potential increases of approximately 96% to 153% in NOx OSD emissions from the Hood County
electric power generation (SIC 4911). Estimated allowable daily emissions represent potential
increases of 18% to 28% in NOx emissions from all Hood County anthropogenic sources relative
to the 2012 TCEQ emission inventory. Average daily estimates shown are not expected to
represent ozone season daily estimates. Ozone season daily emission estimates will depend on
11
http://www.luminant.com/plants/pdf/DeCordova_Facts.pdf
http://www.dallasnews.com/business/energy/20150128-texas-wholesale-power-prices-sliding-alongsidenatural-gas-decline.ece
12
34
March 2015
power plant electric load during ozone season; since the new units are peaking units it is
expected that during summer months they may operate at a higher load than would be
represented by an annual average.
Table 4-6.Hourly maximum allowable emission rate (source: TCEQ Permit Number 107569)
and calculated daily maximum allowable emission rate from additional permitted units at the
DeCordova Power Plant.
NOx
Unit
Unit 5 CTG (GE Option)
Unit 6 CTG (GE Option)
GE Option Subtotal
(lb/hr)
74.98
74.98
149.96
1
(tpd )
0.9
0.9
1.8
NOx (peak firing)
1
(lb/hr)
(tpd )
120
1.4
120
1.4
240
2.9
Unit 5 CTG (Siemens Option)
82.24
1.0
120
Unit 6 CTG (Siemens Option)
82.24
1.0
120
Siemens Option Subtotal
164.48
2.0
240
1
estimated from the hourly emission rate multiplied by 24 hours per day
1.4
1.4
2.9
4.3.2 Wolf Hollow II Power Plant Expansion
The Wolf Hollow Generating Station is located in Hood County and is owned and operated by
Exelon Corporation. This facility, referred to below as Wolf Hollow I, has a generation capability
of 704 MW. Exelon has filed a permit for approval of construction and operation of an
expansion of the Wolf Hollow Power Plant. The expansion project (referred to as Wolf Hollow
II) authorizes construction of two new combined cycle natural gas-fueled CTGs equipped with
pre-mix low NOx combustors and ancillary equipment. Each new CTG will have an approximate
maximum base load electric power output for 330 MW and will use an SCR system to control
NOx emissions and an oxidation catalyst system to control CO and VOC emissions. Construction
of the units is expected to start in 2015 and operation is expected to begin in 201713.
Table 4-7 shows NOx hourly maximum allowable emission rates for the Wolf Hollow II
expansion. Allowable hourly emissions were multiplied by 24 hours per day to estimate
allowable daily emissions from these newly permitted and yet to be constructed units.
Estimated allowable daily emissions represent potential increases of approximately 42% in NOx
OSD emissions from Hood County electric power generation (SIC 4911) and potential increases
of 8% in NOx emissions from all Hood County anthropogenic sources based on comparison to
the 2012 TCEQ emission inventory. Average daily estimates shown are not expected to
represent ozone season daily estimates. Ozone season daily emission estimates depend on the
power plant electric load during ozone season; since the new units are peaking units it is
expected that during summer months they may operate at a higher load than would be
represented by an annual average.
13
http://www.prnewswire.com/news-releases/exelon-generation-to-build-two-new-natural-gas-units-in-texas277448991.html
35
March 2015
Table 4-7. Hourly maximum allowable emission rate (source: TCEQ Permit Number 83638 and
PSDTX1110) and calculated daily maximum allowable emission rate from additional
permitted units at the Wolf Hollow II Power Plant Expansion.
Emission Point
No.
E-ST3
E-ST4
E-AUXBLR2
Source Name
GE 7FA (~170 MW) +
GE 7FA (~170 MW) +
Auxiliary Boiler
Emergency Generator
2
Fire Water Pump 2
Air
Contaminant
Name
NOx
NOx
NOx
Emission Rate
(lb/hour)
18
18
1.42
Calculated
Daily Emission
1
Rate (tpd)
0.22
0.22
0.02
E-GEN2
NOx
23.25
0.28
E-PUMP2
NOx
5.67
0.07
Totals
66.34
0.80
1
Estimated based on hourly emission rate multiplied by 24 hours per day divided by 2,000 pounds per ton.
36
March 2015
5.0 RECOMMENDATIONS
Below is a list of recommended improvements to the TCEQ 2012 area, off‐road and point
source emissions inventories. These recommendations are listed below in order of importance
as determined by Environ; NOx emissions updates are a higher priority than VOC emission
updates because ozone formation in Hood County is known to be NOx-limited (see Conceptual
Model of Ozone in Hood County [Parker et al., 2015]). Because none of these changes is
expected to affect the largest Hood County emission source categories (e.g. power plants and
oil and gas area source compressor engines) none of these updates is considered a high
priority.
1. Emissions from the Cresson rail yard are not included in the 2012 TCEQ emission inventory;
when TCEQ releases documentation of the 2012 locomotive emission inventory the
methodology can be reviewed to determine why these emissions are omitted. Emissions
from this rail yard should be estimated and included in future updates to the TCEQ
locomotive emission inventory if emissions are significant.
2. For the following oil and gas source categories: heaters, pneumatic pumps, fugitive devices,
dehydrators, and well completions, emission calculation assumptions are generally based
on potentially outdated studies or not based on data that encompasses recent drilling and
production activity in the Barnett Shale formation and should be updated.
3. Gasoline distribution volume estimates should be obtained from the Texas Comptroller's
office to verify that reasonable gasoline throughput volumes are used in the ERG (2008a)
study. Obtaining annual gasoline throughput estimates from the Texas Comptroller's office
and comparing those throughput estimates to throughput estimates in ERG (2008a) is likely
to require minimal effort.
Construction and operation of new units at the DeCordova and Wolf Hollow power plants
would increase NOx emissions in Hood County. In 2012 existing emissions from these two
facilities made them the 1st and 4th largest point sources of NOx in Hood County. The ratio of
VOC to NOx emissions in Hood County as well as June 2006 ozone modeling results (Johnson et
al., 2015) indicate that ozone formation in Hood County is limited by the amount of available
NOx. Expansion of the DeCordova and Wolf Hollow power plants through addition of new CTGs
would increase NOx emissions. Because the proposed CTGs would likely operate as peaking
units they would likely have their highest emissions on hot summer days when Hood County is
most likely to experience high ozone. Therefore plans to develop the new units should be
monitored closely and new NOx emissions analyzed to determine their magnitude, variability
and potential ozone impacts.
37
March 2015
6.0 REFERENCES
Baker, R. and D. Preusse, 2009. “Update of Diesel Construction Equipment Emission Estimates
for the State of Texas –Phase I and II. Final report”. Prepared for Texas Commission on
Environmental Quality.
http://www.tceq.state.tx.us/assets/public/implementation/air/am/contracts/reports/ei
/erg‐DCE_EI_Update‐20090731.pdf
Bar-Ilan et al. 2008. Bar-Ilan, Amnon; Parikh, Rajashi; Grant, John; Shah, Tejas; and Pollack,
Alison, 2008. Recommendations for Improvements to the CENRAP States’ Oil and Gas
Emissions Inventories. Prepared by ENVIRON International Corporation for the Central
States Regional Air Partnership. November.
Eastern Research Group, Inc. (ERG). 2008a. Stage I and Stage II Gasoline Dispensing Emissions
inventory: Final. Prepared for the Texas Commission on Environmental Quality. August.
http://www.tceq.texas.gov/assets/public/implementation/air/am/contracts/reports/ei/
5820784003FY0807-20080831-ergi-gasline_despensing_ei.pdf
Eastern Research Group, Inc. (ERG). 2008b. Texas NONROAD (TexN) Model Version 1.0 User’s
Guide. Prepared for the Texas Commission on Environmental Quality. August.
Eastern Research Group, Inc. (ERG). 2010a. Characterization of Oil and Gas Production
Equipment and Develop a Methodology to Estimate Statewide Emissions: Final Report.
Prepared for the Texas Commission on Environmental Quality. November.
5820784003FY1026-20101124-ergi-oilGasEmissionsInventory.pdf
Eastern Research Group, Inc. (ERG). 2010b. Development of Locomotive and Commercial
Marine Emissions Inventory – 1990 to 2040. Prepared for the Texas Commission on
Environmental Quality. July.
Eastern Research Group, Inc. (ERG). 2011. Development of Texas Statewide Drilling Rigs
Emission Inventories for the years 1990, 1993, 1996, and 1999 through 2040. Prepared
for the Texas Commission on Environmental Quality. August.
5821199776FY1105-20110815-ergi-drilling_rig_ei.pdf
Eastern Research Group, Inc. (ERG). 2012. Condensate Tank Oil and Gas Activities Final Report.
Prepared for the Texas Commission on Environmental Quality. October.
Eastern Research Group, Inc. (ERG). 2013. Upstream Oil and Gas Heaters and Boilers Final
Report. Prepared for the Texas Commission on Environmental Quality. August.
Eastern Research Group, Inc. (ERG). 2014. Texas NONROAD Model Update and Enhancement.
Prepared for the Texas Commission on Environmental Quality. August.
Environmental Protection Agency. EPA, 2004. “Nonroad Engine Growth Estimates”. EPA420-P04-008. United States Environmental Protection Agency. April.
http://www.epa.gov/OMS/models/nonrdmdl/nonrdmdl2004/420p04008.pdf
38
March 2015
Guenther, A. B., X. Jiang, C. L. Heald, T. Sakulyanontvittaya, T. Duhl, L. K. Emmons, and X. Wang,
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,
Geosci. Model Dev., 5(6), 1471-1492.
Johnson, J., S. Kemball-Cook, and G. Yarwood. 2015. Photochemical Modeling of June 2006 for
Hood County. Draft report prepared for: Michelle McKenzie, Hood County Clean Air
Coalition, 123 E. Pearl St. #200, Granbury, TX, 76048.
Parker, L., J. Zagunis, S. Kemball-Cook and G. Yarwood. 2015. Conceptual Model of Ozone in
Hood County. Draft report prepared for: Michelle McKenzie, Hood County Clean Air
Coalition, 123 E. Pearl St. #200, Granbury, TX, 76048.
Texas Commission on Environmental Quality (TCEQ). 2015. Personal Communication with TCEQ
staff (Chris Kite). January.
Texas Commission on Environmental Quality (TCEQ). 2014a. Personal Communication with
TCEQ staff (Jim McKay). August.
Texas Commission on Environmental Quality (TCEQ), 2014b. Personal Communication with
TCEQ staff (Michael Ege). August.
Texas Environmental Research Consortium (TERC), October 2006, revised April 2009. VOC
Emissions from Oil and Condensate Storage Tanks.
Thesing, K., 2009. “Development of Emissions Inventory of Agricultural Equipment in all Texas
Counties, Part Two, Final Report Task 6”. Contract No. 582-7-84008, Work Order No.
582-7-84008-FY09-02, Tracking No. 2009-47. Prepared for the TCEQ. August.
39
March 2015
APPENDIX A
Hood County Off-Road and Area Source Emissions
(Area sources include oil and gas area sources)
March 2015
Appendix A. Hood County Off-road and Area Source Emissions
Table A-1. 2012 Hood County off-road and area source NOx emissions (tons per ozone season
day).
Lumped Category
NOx
Off-road
Agricultural Equipment
Construction and Mining Equipment
Drilling Equipment
Locomotives
Pleasure Craft
Commercial Equipment
Industrial Equipment
Lawn and Garden Equipment
Recreational Equipment
VOC
CO
0.52
0.33
0.26
0.07
0.04
0.03
0.02
0.02
<0.00
1.29
0.05
0.04
0.01
<0.00
0.43
0.04
<0.00
0.16
0.01
0.75
0.48
0.26
0.05
0.01
1.37
0.93
0.08
2.05
0.47
5.71
2.86
0.11
0.02
0.01
<0.00
<0.00
2.99
5.11
0.05
0.02
0.03
<0.00
<0.00
0.93
0.59
0.13
0.07
0.05
0.04
0.04
0.04
0.03
0.03
0.03
0.03
0.02
0.01
0.01
<0.00
<0.00
<0.00
<0.00
7.28
1.20
0.31
0.22
0.21
<0.00
<0.00
<0.00
0.01
1.96
Area
Oil and Gas
Fuel Combustion
Waste Disposal
Open Burning
Structural Fires
Vehicle Fires
Gasoline Distribution
Consumer Products
Architectural Coatings
Gasoline Service Stations
Portable Fuel Storage
Textile Products: SIC 22
Industrial Surface Coating
Degreasing
Pesticides
Landfills
Cutback Asphalt
Graphic Arts
Leaks/Spills
Auto Body Refinishing
Traffic Marking
Commercial Cooking - Frying
Dry Cleaning
Commercial Cooking - Charbroiling
Wastewater Treatment
A-1
March 2015
APPENDIX B
Hood County Point Source Emissions
March 2015
Appendix B. Hood County Point Source Emissions
Table B-1.TCEQ 2012 Hood County NOx, VOC, and CO point source emissions (tons per ozone
season day).
NOx Emissions
(tons per ozone
season day)
2012
VOC Emissions
(tons per ozone
season day)
2012
CO Emissions
(tons per ozone
season day)
2012
Facility
SIC
Wolf Hollow I
Corvette Gas Processing Plant
Cowtown Gas Processing Plant
Tolar Gas Plant
4911
1321
1311
4911
4922
1311
1.7003
0.4064
0.3037
0.1835
0.1625
0.1237
0.0092
0.2710
0.0061
0.0448
0.1372
0.2529
4.9959
0.0013
0.0804
0.0038
0.3218
0.0294
Helton Pad
Wellborn Simon Common Bat
1311
1311
1311
1311
1311
1311
0.0927
0.0855
0.0590
0.0529
0.0519
0.0252
0.0054
0.0588
0.0110
0.0109
0.0132
0.0260
0.0114
0.0174
0.0149
0.0076
0.0054
0.1077
Randle A Unit 8H 9H
Brock Unit 4
Kidd C Unit 5H 6H
1311
1311
1311
1311
1311
1311
0.0057
0.0038
0.0038
0.0019
0.0019
0.0019
0.0037
0.0421
0.0106
0.0622
0.0115
0.0101
0.0040
0.0236
0.0400
0.0076
0.0038
0.0038
Randle A Unit 13H
TOTAL
1311
1311
1311
0.0019
0.0019
<0.0001
3.2700
0.0131
0.0127
0.0016
1.0138
0.0038
0.0038
5.6874
B-1

Hood County Emission Inventory Review

Transcription

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