April 2022
Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-2020:
Updates for Gas STAR and Methane Challenge Reductions
This memo documents the updates implemented in EPA's 2022 Inventory of U.S. Greenhouse Gas Emissions
and Sinks (GHGI) due to reassessing Natural Gas STAR ("Gas STAR") reductions and incorporating Methane
Challenge reductions. Additional considerations for using reductions data in the GHGI were previously
discussed in a memo released in September 2021 (Inventory of U.S. Greenhouse Gas Emissions and Sinks 1990-
2020: Updates Under Consideration for Gas STAR and Methane Challenge Reductions).1
1 Background and Previous (1990-2019) GHGI Methodology
For a limited number of emission sources within Natural Gas Systems, EPA applies methane (CH4) emission
factors (EFs) from a 1996 Gas Research Institute (GRI) and EPA study (GRI/EPA study) across the entire 1990-
2019 time series.2 These EFs are representative of technologies and practices in the early 1990's, but not
necessarily of more recent operations. Industry practices and technologies have evolved significantly in the 25
years since the release of the GRI/EPA study. For these emission sources, the methodology first estimated
"potential" emissions with the GRI/EPA factors and then estimated "net" emissions by subtracting voluntary
emissions reductions reported under EPA's Gas STAR program from the potential emissions.3 Throughout this
memo, this is called a "potential methodology". Most other GHGI emission source calculation methodologies
have been updated to use EFs developed from subpart W data or a recently published methane emissions
study; throughout this memo, this is called a "net methodology".
Within the Gas STAR program, voluntary emission reductions are classified as either short- or long-term
reductions. Short-term reductions are assumed to be 1-year reductions and in the GHGI are only applied to
calculated potential emissions in the specific year of implementation. In contrast, long-term reductions are
those reductions which extend beyond the specific year of implementation. Most of these long-term
reductions are the result of capital investments in new equipment, controls, etc. For these sources, the Gas
STAR program assigns a "sunset date", which is the length of time a technology or practice could be considered
to generate emission reductions for the purposes of Gas STAR after implementation. For long-term reductions,
the "sunset date" is either 7 or 10 years. For purposes of the GHGI, EPA assumes that all reported long-term
reductions are permanent (i.e., Gas STAR "sunset dates" are ignored and the identified reductions are applied
to the implementation year and all subsequent years). The net effect of this assumption is that the total annual
quantity of long-term reductions gradually increases over time as more reductions are reported to Gas STAR.
In the previous GHGI (i.e., 1990-2019 GHGI), Gas STAR reductions were applied to the following sources:
• Production Segment
o Gas engines
o Compressor starts
o Other (for activities not assigned to a particular GHGI emission source)
• Transmission and Storage Segment
o Pipeline leaks
o Dehydrator vents (Transmission)
o Engines (Transmission)
o Station venting (Transmission)
1 https://www.epa.gov/system/files/documents/2021-09/2022-ghgi-update-gas-starmc_sept-2021.pdf
2 GRI/EPA 1996. Methane Emissions from the Natural Gas Industry. EPA-600/R-96-080. June 1996.
3 In addition to adjustments for voluntary reductions, regulatory reductions are also applied for one source in the GHGI-production
segment dehydrator vents, to reflect NESHAP reductions. Other sources covered by regulations (such as NSPS) are calculated with a net
methodology.
Page 1 of 17
-------
April 2022
The most recent Gas STAR reduction data that were incorporated into the GHGI were for 2013. These 2013
year reductions were then carried forward as proxy data for the 2014 through 2019 emission years without
new reductions data being incorporated. Table 1 (Production Segment) and Table 2 (Transmission and Storage
Segment) present the numerical Gas STAR reductions used and reported in the previous GHGI. Reductions are
only presented for inventory years 1990, 2005, and 2015-2019 (i.e., the years shown in the main text of the
previous GHGI report); Appendix A presents the numerical Gas STAR reductions for the entire 1990-2019 time
series in the previous GHGI.
Table 1. Annual Production Segment Gas STAR Reductions for 1990, 2005, and 2015-2019 (mt CH4)
in the Previous (2021) GHGI.
Source
1990
2005
2015
2016
2017
2018
2019
Gas Engines
0
96,625
139,167
139,167
139,167
139,167
139,167
Compressor Starts
0
182
512
512
512
512
512
Other
0
100,762
104,624
104,624
104,624
104,624
104,624
Total
0
197,569
244,304
244,304
244,304
244,304
244,304
Table 2. Annual Transmission and Storage Segment Gas STAR Reductions for 1990, 2005, and 2015-
2019 (mt CH4) in the Previous (2021) GHGI.
Source
1990
2005
2015
2016
2017
2018
2019
Pipeline Leaks
0
0
1,213
1,213
1,213
1,213
1,213
Dehydrator vents
0
2,718
2,819
2,819
2,819
2,819
2,819
Engines
0
83,207
126,910
126,910
126,910
126,910
126,910
Station Venting
0
126,310
136,856
136,856
136,856
136,856
136,856
Total
0
212,235
267,799
267,799
267,799
267,799
267,799
2 Update Implemented in the 2022 GHGI
2.1 Gas STAR
EPA replaced the Gas STAR data currently used in the GHGI with a revised dataset including reductions from
1990-20194, adjusted to remove reductions for sources calculated with net methodologies. EPA continued to
treat long-term Gas STAR reductions in the revised dataset in the same manner as the previous GHGI approach
wherein those reductions are assumed to be permanent (see Section 1). Reduction data for 2019 were applied
for 2020, as 2020 data were not yet available.
As part of the overall reassessment of the Gas STAR reductions, EPA examined every Gas STAR activity (i.e., the
list of technologies and practices implemented by companies to mitigate emissions) in the Production,
Transmission and Storage, and Distribution segments.5 First, EPA assigned each Gas STAR reduction activity in
the Production segment and the Transmission and Storage segment to a GHGI emission source; in a few
instances, a Gas STAR reduction activity was assigned to two GHGI emissions sources. EPA also assigned
relevant Gas STAR reduction activities in the Distribution segment to specific Distribution segment emission
sources: pressure relief valve releases, pipeline blowdowns, and mishaps (dig-ins). The Gas STAR reductions
data assessed included a total of 102 Production segment reduction activities, 58 Transmission and Storage
segment reduction activities, and 37 Distribution segment reduction activities.
4 https://edap.epa.gov/public/extensions/NGS/Accomplishments.html
5 EPA did not analyze the Gas STAR activities for the Processing segment as most Processing sources are quantified with net
methodologies.
Page 2 of 17
-------
April 2022
EPA then assessed which Gas STAR reduction activities were related to a GHGI emission source which still used
the "potential methodology" (e.g., the GHGI emission source calculation methodology still relied on data from
the 1996 GRI/EPA study) versus the "net methodology" (i.e., the GHGI emission source calculation
methodology had been updated to use emissions data from subpart W or a recently published methane
emissions study). EPA removed the reduction activities related to a GHGI emission source with a "net
methodology" from further analysis. A total of 40 Production segment reduction activities, 23 Transmission
and Storage segment reduction activities, and 12 Distribution segment reduction activities were determined to
use the "potential methodology". These activities are presented below in Table 3 (Production Segment), Table
4 (Transmission and Storage Segment), and Table 5 (Distribution Segment).
As indicated in the footnotes for Table 3 and Table 4, a few reduction activities were assigned to two GHGI
emissions sources for which one source used the "net methodology" and the other source used the "potential
methodology". For these activities, the reductions were adjusted using a ratio of source-specific emissions
versus overall emissions. For example, the reductions from the Production segment reduction activity (i.e.,
"Capture and use gas released from gas-operated pneumatic pumps") were reduced by the ratio of Kimray
pump emissions to the sum of Kimray pump and chemical injection pump emissions. Likewise, the reductions
from the three Transmission and Storage segment reduction activities that were assigned to two GHGI
emission sources (see the last three rows of Table 4) were reduced using similar ratios.
Table 3. Gas STAR Production Segment Reduction Activities Assigned to GHGI Emission Sources
with a Potential Methodology
Gas STAR Reduction Activity
GHGI Emission Source
Reduce methane emissions from compressor rod packing
systems
Compressors
Automate compressor systems operations to reduce venting
Compressors/Compressor
Blowdowns
Lower compressor purge pressure for shutdown
Compressor Blowdowns
Redesign blowdown/alter ESD practices
Compressor Blowdowns
Reduce emissions when taking compressors offline
Compressor Blowdowns
Convert engine starting to nitrogen and/or C02 rich gas
Compressor Starts
Convert to low pressure compressor starters
Compressor Starts
Install electric motor starters
Compressor Starts
Reduce gas venting with fewer compressor startups and
improved ignition
Compressor Starts
Replace gas starters with air or nitrogen
Compressor Starts
Replace ignition/reduce false starts
Compressor Starts
Install condensers on glycol dehydrators
Dehydrator Vents/Kimray Pumps
Install flash tank separators on glycol dehydrators
Dehydrator Vents/Kimray Pumps
Reduce glycol circulation rates in dehydrators
Dehydrator Vents/Kimray Pumps
Replacing glycol dehydrators with desiccant dehydrators
Dehydrator Vents/Kimray Pumps
Reroute dehydrators/tank vents to flare or station suction
Dehydrator Vents/Kimray Pumps
Reroute glycol skimmer gas
Dehydrator Vents/Kimray Pumps
Shutdown glycol dehydrator stripping gas in winter
Dehydrator Vents/Kimray Pumps
Catalytic converter installation
Engines
Convert natural gas-fired generator to solar power
Engines
Install automated air/fuel ratio controls
Engines
Install electric compressors
Engines
Install electric motors
Engines
Install lean burn compressor
Engines
Page 3 of 17
-------
April 2022
Gas STAR Reduction Activity
GHGI Emission Source
Install pilotless burner controls
Engines
Turbine fuel use optimization
Engines
DI&M at compressor stations
Equipment Leaks
DI&M at remote sites
Equipment Leaks
DI&M: leak detection using IR camera/optical imaging
Equipment Leaks
DI&M: leak detection using lower emission threshold
Equipment Leaks
DI&M: survey and repair leaks
Equipment Leaks
Install plugs on valves and open ended lines
Equipment Leaks
Test and repair pressure safety valves
Equipment Leaks
Capture and use gas released from gas-operated pneumatic
pumps
Kimray Pumps/Chemical Injection
Pumps3
Convert water tank blanket from natural gas to C02
Produced Water
Install flash tank separator on water gathering system
Produced Water
a Kimray pumps use a potential methodology and chemical injection pumps use a net methodology.
Table 4. Gas STAR Transmission and Storage Segment Reduction Activities Assigned to GHGI
Emission Sources with a Potential Methodology.
Gas STAR Reduction Activity
GHGI Emission Source
Install condensers on glycol dehydrators
Dehydrator Vents
Install flash tank separators/controls on transmission sector
glycol dehydrators
Dehydrator Vents
Replace glycol dehydrator with separator and in-line heaters
Dehydrator Vents
Reroute dehydrators/tank vents to flare or station suction
Dehydrator Vents
Reroute glycol skimmer gas
Dehydrator Vents
Install automated air/fuel ratio controls
Engines
Install electric compressors
Engines
Install electric motor starters
Engines
Install electric motors
Engines
Install lean burn compressor
Engines
Replace gas starters with air or nitrogen
Engines
Replace ignition/reduce false starts
Engines
Use of turbines at compressor stations
Engines
DI&M: aerial leak detection using laser and/or infrared
technology
Pipeline Leaks
Inspect/repair valves during pipeline replacement
Pipeline Leaks
Pipeline replacement and repair
Pipeline Leaks
Design isolation valves to minimize gas blowdown volumes
Station Venting
Lower compressor purge pressure for shutdown
Station Venting
Move in fire gates at compressors
Station Venting
Reduce emissions when taking compressors offline
Station Venting/Compressors3
Inject blowdown gas into low pressure mains or fuel gas
system
Station Venting/Pipeline Venting3
Redesign blowdown/alter ESD practices
Station Venting/Pipeline Venting3
a Station venting uses a potential methodology and pipeline venting and compressor emissions are
estimated using net methodologies.
Page 4 of 17
-------
April 2022
Table 5. Gas STAR Distribution Segment Reduction Activities Assigned to GHGI Emission Sources
with a Potential Methodology.
Gas STAR Reduction Activity
GHGI Emission Source
Install excess flow valves
Mishaps (Dig-ins)
Reduced emissions through third-party damage prevention
Mishaps (Dig-ins)
Inject blowdown gas into low pressure mains or fuel gas
system
Pipeline Blowdown
Install overpressure protection system
Pipeline Blowdown
Redesign blowdown/alter ESD practices
Pipeline Blowdown
Reduce/downgrade system pressure
Pipeline Blowdown
Reduce/downgrade system pressure (manual)
Pipeline Blowdown
Use automated systems to reduce pressure
Pipeline Blowdown
Use hot taps for in-service pipeline connections
Pipeline Blowdown
Use pipeline pump-down techniques to lower gas line
pressure
Pipeline Blowdown
Test and repair pressure safety valves
Pressure Relief Valve Releases
Test gate station pressure relief valves with nitrogen
Pressure Relief Valve Releases
Tables 6, 7, and 8 present a summary of the year 2019 Gas STAR reductions by GHGI emission source (all Gas
STAR reductions are summed together for a common GHGI emission source) for the Production segment, the
Transmission and Storage segment, and the Distribution segment, respectively. Appendix B presents the
complete time series of Gas STAR reductions of each emission source in Tables 6, 7, and 8.
Table 6. Year 2019 Production Segment Gas STAR Reductions by Emission Source (mt CH4).
GHGI Emission Source
Gas STAR Reductions
Compressor Blowdowns
4,499
Compressor Starts
16,954
Compressors
48
Dehydrator Vents/Kimray Pumps
50,911
Engines
32,147
Equipment Leaks
85
Kimray Pumps
166
Produced Water
1,023
Total
105,833
Table 7. Year 2019 Transmission and Storage Segment Gas STAR Reductions by Emission Source (mt CH4).
GHGI Emission Source
Gas STAR Reductions
Dehydrator Vents
4,089
Engines
132,410
Pipeline Leaks
590
Station Venting
21,418
Total
158,507
Page 5 of 17
-------
April 2022
Table 8. Year 2019 Distribution Segment Gas STAR Reductions by Emission Source (mt CH4).
GHGI Emission Source
Gas STAR Reductions
Pressure Relief Valve Releases
0a
Pipeline Blowdowns
2,202
Mishaps (Dig-ins)
1,383
Total
3,586
a Gas STAR reductions were not reported for pressure relief valve
releases in year 2019; however, reductions were reported for other
years in the time series.
In order to correspond with GHGI emission sources, EPA disaggregated Gas STAR reductions for production
segment "dehydrator vents/Kimray pumps" and "equipment leaks" to the individual GHGI emission sources.
EPA applied the average source-specific distribution of emissions over the entire time series to estimate the
reductions for each emission source (e.g., production segment separator emissions account for 48 percent of
equipment leak emissions over the 1990-2020 time series and EPA assigned 48 percent of the equipment leak
Gas STAR reductions to separators):
• Dehydrator vents/Kimray pumps
o Dehydrator vents - 24 percent
o Kimray pumps - 76 percent
• Equipment leaks
o Heaters - 9 percent
o Separators - 48 percent
o Dehydrators - 6 percent
o Meters/piping - 37 percent
2.2 Methane Challenge
EPA's Methane Challenge Program has collected reductions data starting with reductions reported for 2016.
EPA incorporated these data into the GHGI.
Methane Challenge data are available for two commitment options (Best Management Practice Commitment
Option (BMP) and the ONE Future Emissions Intensity Commitment Option [ONE Future]) and reductions for
both commitment options are considered. BMP partners make a commitment to implement mitigation
activities for specific emission sources and the list of emission sources varies by industry segment. ONE Future
partners make a commitment to achieve a ONE Future-defined target segment intensity rate by 2025 for all
their operations in the segment and may implement mitigation activities for any of their emission sources to
achieve that rate. For both options, partners report the emissions reductions achieved in a given year as a
result of implementing specific mitigation activities to achieve their commitment. BMP emissions reductions
are available for years 2016-2019 and ONE Future emissions reductions are available for years 2017-2019.6
Table 9 presents the Methane Challenge reductions by industry segment and emission source for 2016-2019.
Table 9 also shows the Methane Challenge emission sources that are related to GHGI emission sources with a
potential methodology.
6 https://www.epa.gov/natural-gas-star-program/methane-challenge-program-accomplishments
Page 6 of 17
-------
April 2022
Table 9. Methane Challenge CH4 Emission Reductions by Emission Source (mt CH4) and
Identification of Sources That Use a Potential Methodology.
Methane Challenge
Emission Source
2016
2017
2018
2019
GHGI Emission Source
Uses a Potential
Methodology?
Transmission Segment
Transmission Pipeline
Blowdowns
4,787
58,113
98,147
74,971
No
Equipment Leaks
[transmission station leaks]
0
3,411
8,314
15,118
No
Reciprocating Compressors
0
621
583
911
No
Pneumatic Controllers
0
6
184
215
No
Distribution Segment
Distribution Mains
2,449
8,974
8,709
9,652
No
Distribution Services
1,014
3,126
2,528
2,682
No
Distribution Pipeline
Blowdowns
0
4
802
192
Yes
Pressure Relief Valves
0
789
52
47
Yes
Onshore Production
Storage Tanks
0
0
0
14
No
Gathering and Boosting
Reciprocating Compressors
0
0
0
196
No
Only two sources with Methane Challenge reductions use a potential methodology in the GHGI and both are in
the distribution segment. For 2016-2019 in the 2022 GHGI, distribution pipeline blowdown emissions average
4,400 mt CH4 and pressure relief valve releases average 1,300 mt CH4.
3 Time Series Considerations
Gas STAR reductions are available over the entire time series. Methane Challenge data are available for year
2016 forward. With the exception of the long-term GasSTAR reductions discussed in Section 2.1, EPA applied
the reductions data only to the years reported and did not make adjustments to other years of the time series.
Upon comparing the reductions data to the potential emissions over the time series for each emission source,
there were a number of instances where the reductions exceeded the potential emissions resulting in
"negative emissions". The sources with calculated negative net emissions (and years of negative emissions)
include:
• Production Segment
o Compressor blowdowns (2001-2020)
o Compressor starts (1994-2020)
o Dehydrator vents (2010-2011)
• Transmission segment
o Dehydrator vents (1997-2020)
o Pipeline leaks (1998-1999, 2007-2012, 2014, 2017-2018)
• Distribution segment
o Pipeline blowdowns (1997, 2005-2006)
o PRV releases (2002)
Page 7 of 17
-------
April 2022
EPA removed Gas STAR reductions entirely for sources with more than 10 years of negative calculated
emissions (i.e., production segment compressor blowdowns and compressor starts, and transmission segment
dehydrator vents and pipeline leaks).
For the remaining sources with negative emissions (i.e., production segment dehydrator vents and distribution
segment pipeline blowdowns and PRV releases), calculated negative emissions occur for a maximum of three
years in the time series. EPA replaced the negative net emissions value with zero for the years of negative net
emissions for these sources.
4 National Emissions Estimates
Tables 10, 11, and 12 present the impact of Gas STAR and Methane Challenge voluntary reductions, along with
regulatory reductions, for the Production, Transmission and Storage, and Distribution segments in the GHGI.
Appendix C presents the complete time series of reductions used for each emission source in the 2022 GHGI.
The reductions in Tables 10 - 12 and Appendix C reflect the adjustments presented in Section 2 (to
disaggregate emissions) and Section 3 (to exclude certain reductions that resulted in negative net emissions
values).
Table 10. Year 2019 Production Segment Potential and Net Emissions with Reductions (mt CH4).
Parameter
Emissions/Reductions
Previous (2021) GHGI
Emissions/Reductions
Current (2022) GHGI
Potential Emissions
3,992,187
3,801,962
Gas STAR Reductions
236,934
84,380
Regulatory Reductions3
7,370
7,370
Net Emissions
3,747,883
3,710,212
a. Regulatory reductions include the impacts of EPA National Emission Standards for Hazardous Air Pollutants
(NESHAP) regulations for dehydrator vents.
Table 11. Year 2019 Transmission and Storage Segment Potential and Net Emissions with
Reductions (mt CH4).
Parameter
Emissions/Reductions
Previous (2021) GHGI
Emissions/Reductions
Current (2022) GHGI
Potential Emissions
1,746,133
1,736,643
Gas STAR Reductions
267,799
153,828
Net Emissions
1,478,334
1,582,815
Table 12. Year 2019 Distribution Segment Potential and Net Emissions with Reductions (mt CH4).
Parameter
Emissions/Reductions
Previous (2021) GHGI
Emissions/Reductions
Current (2022) GHGI
Potential Emissions
559,880
559,199
Gas STAR Reductions
0
3,586
Methane Challenge Reductions
0
239
Net Emissions
559,880
555,375
5 Requests for Stakeholder Feedback
EPA sought stakeholder feedback on the approaches under consideration through two 2021 webinars, in the
September 2021 memo, and in the public review draft of the GHGI. EPA received stakeholder comments on
Page 8 of 17
-------
April 2022
the September 2021 version of the memo and through the public review draft of the Inventory. Stakeholder
feedback is summarized here.
Stakeholders agreed with using updated Gas STAR reductions and with the incorporation of Methane
Challenge reductions. One stakeholder supported the approach of treating long-term reductions as permanent
reductions instead of applying long-term reductions that incorporate sunset dates.
The requests for stakeholder feedback below were not updated for this memorandum and are copied from the
September 2021 memorandum:
EPA seeks stakeholder feedback on the update under consideration discussed in this memo and the questions
below.
1. Are the Gas STAR reduction activity assignments to GHGI emission sources in Tables 3-5 appropriate?
2. Are there any Gas STAR activities identified in Tables 3 - 5 as having a potential methodology that
should be considered to have a net methodology?
3. Are there other data sources available to quantify emissions or reductions for the identified sources?
Page 9 of 17
-------
April 2022
Appendix A. Previous (2021) GHGI Gas STAR Reductions
A-l. Previous (2021) GHGI Annual Production Segment Gas STAR Reductions for 1990-2019 (mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Gas Engines
0
0
0
3,217
6,845
12,456
20,855
28,958
34,950
43,414
Compressor
Starts
0
0
0
0
0
3
5
6
117
117
Other
0
0
0
5,562
20,524
29,361
59,362
60,621
75,855
81,560
Total
0
0
0
8,778
27,369
41,820
80,222
89,586
110,922
125,091
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Gas Engines
51,862
60,473
69,101
74,801
87,824
96,625
103,170
110,329
115,060
121,762
Compressor
Starts
117
179
179
179
182
182
182
189
197
395
Other
76,656
83,116
77,643
95,796
99,957
100,762
93,875
98,577
107,160
102,361
Total
128,635
143,768
146,923
170,777
187,962
197,569
197,226
209,096
222,417
224,517
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Gas Engines
132,021
135,866
138,672
139,167
139,167
139,167
139,167
139,167
139,167
139,167
Compressor
Starts
512
512
512
512
512
512
512
512
512
512
Other
104,184
99,639
99,772
104,624
104,624
104,624
104,624
104,624
104,624
104,624
Total
236,718
236,017
238,956
244,304
244,304
244,304
244,304
244,304
244,304
244,304
A-2. Previous (2021) GHGI Annual Transmission and Storage Segment Gas STAR Reductions for 1990-2019
(mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Pipeline Leaks
0
0
0
0
0
33
0
0
0
0
Dehydrator
vents
(Transmission)
0
0
0
0
0
0
755
3,249
3,225
3,182
Engines
(Transmission)
0
0
0
2,803
7,725
12,547
15,909
19,339
40,719
45,526
Station Venting
(Transmission)
0
0
0
2,740
1,416
5,161
7,239
23,627
42,847
58,878
Total
0
0
0
5,543
9,141
17,742
23,904
46,215
86,790
107,586
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Pipeline Leaks
0
0
0
0
0
0
0
0
0
1,136
Dehydrator
vents
(Transmission)
2,718
2,718
2,718
2,718
2,718
2,718
2,840
2,819
2,819
2,819
Engines
(Transmission)
49,291
54,241
68,381
72,424
77,975
83,207
87,797
94,454
103,082
116,170
Station Venting
(Transmission)
77,530
106,355
119,998
125,039
127,850
126,310
146,461
129,026
161,055
136,592
Total
129,539
163,313
191,098
200,181
208,543
212,235
237,097
226,299
266,956
256,718
Page 10 of 17
-------
April 2022
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Pipeline Leaks
0
2,773
4,199
1,213
1,213
1,213
1,213
1,213
1,213
1,213
Dehydrator
vents
2,819
2,819
2,819
2,819
2,819
2,819
2,819
2,819
2,819
2,819
(Transmission)
Engines
(Transmission)
119,382
121,688
124,050
126,910
126,910
126,910
126,910
126,910
126,910
126,910
Station Venting
(Transmission)
135,250
134,419
135,824
136,856
136,856
136,856
136,856
136,856
136,856
136,856
Total
257,451
261,700
266,891
267,799
267,799
267,799
267,799
267,799
267,799
267,799
Page 11 of 17
-------
April 2022
Appendix B. Updated Gas STAR Reductions
Appendix B reflects the updated Gas STAR reductions data that was assessed for the 2022 GHGI, and does not
include adjustments other than treating long-term reductions as permanent reductions (i.e., these data do not
reflect the adjustments presented in Section 2 (to disaggregate emissions) and Section 3 (to exclude certain
reductions that resulted in negative net emissions values)).
B-l. Annual Production Segment Gas STAR Reductions, by GHGI Emission Source, for 1990-2019 (mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Compressors
0
0
0
0
0
0
0
0
0
0
Compressor
Blowdowns
0
0
0
46
61
94
94
95
95
103
Compressor
Starts
0
0
0
391
6,891
6,893
9,939
12,705
12,893
12,816
Dehydrator
Vents/Kimray
Pumps
0
0
0
3,766
5,051
6,862
12,391
20,007
22,873
22,769
Engines
0
0
0
3,037
3,847
5,831
8,618
8,323
6,259
9,123
Equipment
Leaks
0
0
0
0
9
250
594
790
9,678
14,378
Kimray
Pumps
0
0
0
0
0
0
0
0
65
0
Produced
Water
0
0
0
0
0
0
0
0
0
0
Total
0
0
0
7,240
15,858
19,931
31,636
41,920
51,864
59,189
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Compressors
0
0
0
0
0
2,790
957
451
984
981
Compressor
Blowdowns
125
3,828
4,132
9,103
4,450
4,450
5,407
5,908
6,244
6,161
Compressor
Starts
12,833
13,030
13,116
13,118
13,707
14,269
14,344
14,379
17,705
15,416
Dehydrator
Vents/Kimray
Pumps
24,369
28,742
26,836
30,737
32,510
35,434
43,333
52,245
63,917
70,806
Engines
9,498
9,790
10,472
7,928
15,928
12,250
13,399
18,650
17,646
20,610
Equipment
Leaks
8,117
9,082
9,097
22,792
24,792
20,118
29,246
23,927
42,160
39,416
Kimray
Pumps
0
0
0
0
0
0
42
822
2,530
424
Produced
Water
628
628
628
628
628
628
686
1,023
1,023
1,023
Total
55,570
65,099
64,282
84,306
92,015
89,939
107,414
117,405
152,208
154,836
Page 12 of 17
-------
April 2022
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Compressors
333
1,769
48
48
48
51
51
48
48
48
Compressor
Blowdowns
19,802
4,510
4,500
5,211
5,224
5,566
4,633
4,499
4,499
4,499
Compressor
Starts
16,126
15,240
15,238
15,927
15,932
15,909
15,909
15,909
15,909
16,954
Dehydrator
Vents/Kimray
Pumps
76,552
82,728
48,177
49,987
49,987
50,043
50,125
51,798
50,125
50,911
Engines
29,069
29,208
29,074
28,817
30,100
32,255
30,938
44,629
31,396
32,147
Equipment
Leaks
50,043
48,832
13,191
12,261
5,102
4,049
6,477
2,700
23
85
Kimray
Pumps
278
166
166
166
167
166
166
166
166
166
Produced
Water
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
Total
193,226
183,476
111,417
113,441
107,583
109,063
109,322
120,772
103,190
105,833
B-2. Annual Transmission and Storage Segment Gas STAR Reductions, by GHGI Emission Source, for 1990-
2019 (mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Dehydrator
Vents
0
0
0
61
74
77
849
3,374
3,371
3,341
Engines
0
0
0
2,803
6,007
9,108
11,438
13,495
35,790
37,132
Pipeline Leaks
0
0
0
136
0
33
465
0
21,251
3,382
Station Venting
0
0
0
1,071
429
1,164
1,650
916
1,239
1,113
Total
0
0
0
4,071
6,510
10,381
14,402
17,784
61,652
44,969
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Dehydrator
Vents
3,219
3,415
3,367
3,318
3,229
3,135
2,860
2,759
2,759
2,759
Engines
38,732
44,477
56,309
57,719
65,869
70,824
73,845
80,627
86,944
98,272
Pipeline Leaks
0
0
0
0
0
2
0
6,929
3,659
4,098
Station Venting
2,246
3,766
2,590
6,563
5,069
2,032
9,255
1,664
6,140
3,350
Total
44,197
51,658
62,266
67,600
74,167
75,993
85,960
91,978
99,502
108,479
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Dehydrator
Vents
2,759
2,759
2,759
2,759
2,759
2,759
2,759
2,759
2,759
4,089
Engines
86,793
87,773
91,931
91,575
95,736
97,156
97,258
97,084
115,091
132,410
Pipeline Leaks
5,066
6,972
6,972
1,919
4,179
1,194
2,534
4,085
4,083
590
Station Venting
3,475
2,541
3,258
3,556
3,243
3,639
18,151
25,998
28,402
21,418
Total
98,093
100,044
104,919
99,809
105,918
104,748
120,701
129,926
150,335
158,507
Page 13 of 17
-------
April 2022
B-3. Annual Distribution Segment Gas STAR Reductions, by GHGI Emission Source, for 1990-2019 (mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Pressure Relief
Valve Releases
0
0
0
0
0
0
0
0
193
0
Pipeline
Blowdowns
0
0
0
963
1,813
1,258
1,555
4,270
1,468
1,550
Mishaps (Dig-
ins)
0
0
0
0
0
13
18
39
38
61
Total
0
0
0
963
1,813
1,272
1,573
4,308
1,699
1,611
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Pressure Relief
Valve Releases
0
0
1,490
0
0
1
10
0
143
0
Pipeline
Blowdowns
1,502
1,607
3,111
2,645
3,609
5,986
8,804
3,024
3,034
2,652
Mishaps (Dig-
ins)
13
42
51
100
343
618
816
2,382
1,101
1,495
Total
1,516
1,650
4,652
2,744
3,952
6,605
9,630
5,406
4,278
4,147
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
Pressure Relief
Valve Releases
0
0
0
0
0
0
0
0
0
0
Pipeline
Blowdowns
3,021
2,200
1,988
2,170
1,871
2,282
2,022
2,334
2,801
2,202
Mishaps (Dig-
ins)
1,593
5,441
1,415
1,891
2,054
1,978
2,188
1,420
1,331
1,383
Total
4,614
7,642
3,403
4,062
3,925
4,260
4,209
3,754
4,133
3,586
Page 14 of 17
-------
April 2022
Appendix C. Adjusted Gas STAR Reductions Applied for the 2022 GHGI
Update
Appendix C reflects the Gas STAR reductions data as applied for the 2022 GHGI, and includes the adjustments
presented in Section 2 (to disaggregate emissions) and Section 3 (to exclude certain reductions that resulted in
negative net emissions values)).
C-l. Annual Production Segment Adjusted Gas STAR Reductions, by GHGI Emission Source, for 1990-2020
(mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Compressors
0
0
0
0
0
0
0
0
0
0
Compressor
Blowdowns3
0
0
0
0
0
0
0
0
0
0
Compressor Starts3
0
0
0
0
0
0
0
0
0
0
Dehydrator
Vents/Kimray
Pumps
0
0
0
3,766
5,051
6,862
12,391
20,007
22,873
22,769
Dehy Vents
0
0
0
904
1,212
1,647
2,974
4,802
5,490
5,464
Kimray Pumps
0
0
0
2,862
3,839
5,215
9,417
15,205
17,384
17,304
Engines
0
0
0
3,037
3,847
5,831
8,618
8,323
6,259
9,123
Equipment Leaks
0
0
0
0
9
250
594
790
9,678
14,378
Heaters
0
0
0
0
1
21
51
67
823
1,222
Separators
0
0
0
0
4
120
286
380
4,655
6,916
Dehydrators
0
0
0
0
1
16
38
51
619
920
Meters/Piping
0
0
0
0
3
93
220
292
3,581
5,320
Kimray Pumps
0
0
0
0
0
0
0
0
65
0
Produced Water
0
0
0
0
0
0
0
0
0
0
Total
0
0
0
6,803
8,907
12,944
21,604
29,119
38,875
46,270
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Compressors
0
0
0
0
0
2,790
957
451
984
981
Compressor
Blowdowns3
0
0
0
0
0
0
0
0
0
0
Compressor Starts3
0
0
0
0
0
0
0
0
0
0
Dehydrator
Vents/Kimray
Pumps
24,369
28,742
26,836
30,737
32,510
35,434
43,333
52,245
63,917
70,806
Dehy Vents
5,849
6,898
6,441
7,377
7,802
8,504
10,400
12,539
15,340
16,994
Kimray Pumps
18,521
21,844
20,396
23,360
24,708
26,930
32,933
39,706
48,577
53,813
Engines
9,498
9,790
10,472
7,928
15,928
12,250
13,399
18,650
17,646
20,610
Equipment Leaks
8,117
9,082
9,097
22,792
24,792
20,118
29,246
23,927
42,160
39,416
Heaters
690
772
773
1,937
2,107
1,710
2,486
2,034
3,584
3,350
Separators
3,904
4,369
4,376
10,963
11,925
9,677
14,068
11,509
20,279
18,959
Dehydrators
519
581
582
1,459
1,587
1,288
1,872
1,531
2,698
2,523
Meters/Piping
3,003
3,360
3,366
8,433
9,173
7,444
10,821
8,853
15,599
14,584
Kimray Pumps
0
0
0
0
0
0
42
822
2,530
424
Produced Water
628
628
628
628
628
628
686
1,023
1,023
1,023
Total
42,612
48,242
47,034
62,085
73,858
71,220
87,663
97,119
128,258
133,260
Page 15 of 17
-------
April 2022
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
Compressors
333
1,769
48
48
48
51
51
48
48
48
48
Compressor
Blowdowns3
0
0
0
0
0
0
0
0
0
0
0
Compressor
Starts3
0
0
0
0
0
0
0
0
0
0
0
Dehydrator
Vents/Kimray
Pumps
75,140b
79,345b
48,177
49,987
49,987
50,043
50,125
51,798
50,125
50,911
50,911
Dehy Vents
18,372
19,855
11,562
11,997
11,997
12,010
12,030
12,431
12,030
12,219
12,219
Kimray Pumps
58,179
62,874
36,614
37,990
37,990
38,033
38,095
39,366
38,095
38,692
38,692
Engines
29,069
29,208
29,074
28,817
30,100
32,255
30,938
44,629
31,396
32,147
32,147
Equipment Leaks
50,043
48,832
13,191
12,261
5,102
4,049
6,477
2,700
23
85
85
Heaters
4,254
4,151
1,121
1,042
434
344
551
229
2
7
7
Separators
24,071
23,488
6,345
5,898
2,454
1,947
3,115
1,299
11
41
41
Dehydrators
3,203
3,125
844
785
327
259
415
173
1
5
5
Meters/Piping
18,516
18,068
4,881
4,537
1,888
1,498
2,396
999
9
31
31
Kimray Pumps
278
166
166
166
167
166
166
166
166
166
166
Produced Water
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
1,023
Total
155,886
160,342
91,679
92,302
86,427
87,587
88,780
100,364
82,782
84,380
84,380
a EPA removed Gas STAR reductions entirely for sources with more than 10 years of negative calculated emissions:
compressor blowdowns and compressor starts.
b EPA reduced GAS STAR reductions for dehydrator vents (2010-2011) to prevent negative calculated emissions.
C-2. Annual Transmission and Storage Segment Adjusted Gas STAR Reductions, by GHGI Emission Source, for
1990-2020 (mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Dehydrator Vents3
0
0
0
0
0
0
0
0
0
0
Engines
0
0
0
2,803
6,007
9,108
11,438
13,495
35,790
37,132
Pipeline Leaks3
0
0
0
0
0
0
0
0
0
0
Station Venting
0
0
0
1,071
429
1,164
1,650
916
1,239
1,113
Total
0
0
0
3,874
6,436
10,272
13,088
14,410
37,029
38,246
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Dehydrator Vents3
0
0
0
0
0
0
0
0
0
0
Engines
38,732
44,477
56,309
57,719
65,869
70,824
73,845
80,627
86,944
98,272
Pipeline Leaks3
0
0
0
0
0
0
0
0
0
0
Station Venting
2,246
3,766
2,590
6,563
5,069
2,032
9,255
1,664
6,140
3,350
Total
40,978
48,243
58,900
64,282
70,938
72,856
83,101
82,291
93,084
101,622
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
Dehydrator
Vents3
0
0
0
0
0
0
0
0
0
0
0
Engines
86,793
87,773
91,931
91,575
95,736
97,156
97,258
97,084
115,091
132,410
132,410
Pipeline Leaks3
0
0
0
0
0
0
0
0
0
0
0
Station
Venting
3,475
2,541
3,258
3,556
3,243
3,639
18,151
25,998
28,402
21,418
21,418
Total
90,268
90,314
95,189
95,131
98,980
100,796
115,408
123,082
143,493
153,828
153,828
a EPA removed Gas STAR reductions entirely for sources with more than 10 years of negative calculated emissions:
dehydrator vents and pipeline leaks.
Page 16 of 17
-------
April 2022
C-3. Annual Distribution Segment Adjusted Gas STAR Reductions, by GHGI Emission Source, for 1990-2020
(mt CH4).
GHGI Source
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Pressure Relief
Valve Releases
0
0
0
0
0
0
0
0
193
0
Pipeline
Blowdowns
0
0
0
963
1,813
1,258
1,555
3,407a
1,468
1,550
Mishaps (Dig-
ins)
0
0
0
0
0
13
18
39
38
61
Total
0
0
0
963
1,813
1,272
1,573
3,446
1,699
1,611
GHGI Source
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
Pressure Relief
Valve Releases
0
0
l,092a
0
0
1
10
0
143
0
Pipeline
Blowdowns
1,502
1,607
3,111
2,645
3,609
3,855a
3,973a
3,024
3,034
2,652
Mishaps (Dig-
ins)
13
42
51
100
343
618
816
2,382
1,101
1,495
Total
1,516
1,650
4,254
2,744
3,952
4,474
4,798
5,406
4,278
4,147
GHGI Source
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
Pressure Relief
Valve Releases
0
0
0
0
0
0
0
0
0
0
0
Pipeline
Blowdowns
3,021
2,200
1,988
2,170
1,871
2,282
2,022
2,334
2,801
2,202
2,202
Mishaps (Dig-
ins)
1,593
5,441
1,415
1,891
2,054
1,978
2,188
1,420
1,331
1,383
1,383
Total
4,614
7,642
3,403
4,062
3,925
4,260
4,209
3,754
4,133
3,586
3,586
a EPA reduced GAS STAR reductions for pressure release valves (2002) and pipeline blowdowns (1997, 2005-2006) to
prevent negative calculated emissions.
Page 17 of 17
------- |