# 3.4. Methodology for Estimating CH 4 

# and CO 2 

# Emissions from Natural Gas Systems

The following steps were used to estimate CH 4 

### and non-energy CO 2 

### emissions from natural gas systems.

Step 1: Calculate Emission Estimates for Base Year 1992 Using EPA Adjusted GRI/EPA Study

The first step in estimating CH 4 

### and non-energy related (i.e., fugitive, vented and flared) CO 2 

### emissions from

natural gas systems was to develop a detailed base year esti mate of emissions. The study by EPA/GRI (1996) divides the

industry into four stages to construct a detailed emission inventory for the year 1992. These stages include: field

production, processing, transmission and storage (i.e., both underground and liquefied gas storage), and distribution. This

study produced emission factors and activity data for over 80 different emission sources within the natural gas system.

Emissions for 1992 were estimated by multiplying activity levels by emission factors for each system component and then

summing by stage. Since publication, the EPA has updated activity data for some of the components in the system based

on publicly available data. For other sources where annual activit y data are not available, a set of industry activity factor

drivers was developed that can be used to update activity data. Table A- 118 through Table A- 121 display the 2008

activity levels, CH 4 

### emission factors, and CH 4 

### emissions for each stage.. These data are shown to illustrate the kind of

data used to calculate CH 4 

### and non-energy CO 2 

### emissions from all stages. For most sources, the CH 4 

### emission factors

were adjusted for CO 2 

### content when estimating fugitive and vented non-energy CO 2 

### emissions. In the case of non-energy

CO 2 

### emissions from flared sources, acid gas removal units and condensate tanks, specific industry data related to those

sources was used to derive their respective emission factors.

The activity levels and CH 4 

### emission factors in Table A- 118 are arranged into regions designated by the

National Energy Modeling System (NEMS). NEMS splits the continental United States into 6 regions: Northeast, MidCentral, Rocky Mountain, South West, West Coast and Gulf Coas t. GRI, however, does not evaluate activity data for each

of these regions separately. The GRI national AF estimates we re allocated to the NEMS regions using the NEMS regional

gas well counts to national well count ratios.

Step 2: Collect Aggregate Statistics on Main Driver Variables

As detailed data on each of the over 80 sources were not available for the period 1990 through 2008, activity

levels were estimated using aggregate statistics on key dr ivers, including: number of producing wells (EIA 2009a-b, New

Mexico 2009a-b, Texas 2009a-b), number of gas plants (AGA 1991-1997; OGJ 1998-2009), number of shallow and deep

offshore platforms (MMS 2009a-d), miles of transmission pipeline (OPS 2009a), miles of distribution pipeline (OPS

2009b), miles of distribution services (OPS 2009b), and energy consumption (EIA 2009c).

A-149

### Table A- 122 provides the activity levels of some of the key drivers in the natural gas analysis.

Step 3: Estimate CH 4 

### Emissions for Each Year and Stage

Emissions from each stage of the natural gas industry were estimated by multiplying the activity factors by the

appropriate emission factors, summing all sources for each stage and then accounting for CH 4 

### reductions reported to the

Natural Gas STAR Program and CH 4 

### reductions resulting from National Emission Standards for Hazardous Air Pollutants

(NESHAP) regulations.

Industry partners report CH 4 

### emission reductions by project to the Natural Gas STAR Program. The reductions

are estimates using actual measurement data or equipment-spec ific emission factors. Before incorporating the reductions

into the Inventory, quality assurance and quality control checks are undertaken to identify errors, inconsistencies, or

irregular data. The checks include matching Natural Gas STAR reported reductions to specific inventory sources to make

sure that a reported reduction for one source is not greater than the emission estimate for that source. Total emissions were

estimated by adding the emission estimates from each stage. The base year of the inventory is 1992; therefore any

reductions reported for 1992 or earlier are considered to be already included in the base-year emission factors and are not

subtracted from the inventory estimate. If the reported reduction occurred between 1990 and 1992, then the reduction is

added back into the estimate for the appropriate year(s). The reductions are also adjusted to remove the sunsetting time

period which is relevant to Natural Gas STAR accounting but not the Inventory. For example, replacing a gas-assisted

pump with an electric pump permanently reduces the vented methane emissions from that source, even after the Natural

Gas STAR sunsetting period. CH 4 

### emission reductions from the Natural Gas ST AR Program beyond the efforts reflected

in the 1992 base year are summarized in Table A- 123.

The 1990 Clean Air Act (CAA) sets the limits on the amount of hazardous air pollutants (HAPs) that can be

emitted in the United States. The NESHAP regulations set the standards to limit emissions of HAPs. The emission sources

are required to use the Maximum Achievable Control Technology, giving the operators flexibility to choose the type of

control measure(s) to implement. In regards to the oil a nd natural gas industry, the NESHAP regulation addresses HAPs

from the oil and natural gas production sectors and the natura l gas transmission and storage sectors of the industry.

Though the regulation deals specifically with HAPs reductions, methane emissions are also reduced.

The NESHAP regulation requires that glycol dehydration unit vents and storage tanks that have HAP emissions

and exceed a gas throughput and liquids throughput value, respectively, be connected to a closed loop emission control

system that reduces emissions by 95 percent. Also, gas processing plants exceeding the threshold natural gas throughput

limit are required to routinely implement Leak Detection and Survey (LDAR) programs. The emissions reductions

achieved as a result of NESHAP regulations were estimate d using data provided in the Federal Register Background

Information Document (BID) for this regulation. The BID provides the levels of control measures in place before the

enactment of regulation. The emissions reductions were estimated by analyzing the portion of the industry without control

measures already in place that would be impacted by the re gulation. The reductions are representative of the control

measures in both the oil and natural gas industry. CH 4 

### emission reductions from the NESHAP regulation are summarized

in Table A- 124.

Step 4: Estimate CO 2 

### Emissions for Each Year and Stage

The same procedure for estimating CH 4 

### emissions holds true for estimating non-energy related CO 2 

### emissions,

except the emission estimates are not corrected for reductions due to the Natural Gas STAR program or the NESHAP

regulations.

Produced natural gas is composed of primarily CH 4 

### , but as shown in Table A- 129, the natural gas contains, in

some cases, as much as 8 percent CO 2 

### . The same vented and fugitive emissions of natural gas that led to CH 4 

### emissions

also contain a certain volume of CO 2 

### . Accordingly, the CO 2 

### emissions for each sector can be estimated using the same

methane activity and emissions factors for these vented and f ugitive sources. The primary difference is that EPA/GRI

emission factors are adjusted for CO 2 

### content in each sector.

Using the default CH 4 

### content of produced natural gas from EPA/GRI (1996) of 78.8 percent, the corresponding

amount of CO 2 

### emissions from the production sector can be estimated. Each sector of the natural gas system has varying

CO 2 

### contents, similar to the way the CH 4 

### content varies among the sectors. Table A- 129 shows the CO 2 

### content for the

different well types in the production sector of the natural gas system. In the estimation of CO 2 

### emissions from the

production sector, the production sector CH 4 

### emission factors were used as a basis to estimate CO 2 

### emissions; however,

they were converted to CO 2 

### emission factors by multiplication by a conversion factor. This conversion factor is the ratio

of CO 2 

### content in the gas stream (in this case the production concentrations provided in Table A- 129) to the

corresponding CH 4 

### content of the same gas stream. The three exceptions to this methodology are CO 2 

### emissions from

A-142 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008

### flares, acid gas removal units, and condensate tanks. In the case of flare emissions, a direct CO 2 

### emission factor from EIA

(1996) was used. This emission factor was applied to the portion of offshore gas that is not vented and all of the gas

reported as vented and flared onshore by EIA. The amount of CO 2 

### emissions from an acid gas unit in a processing plant is

equal to the difference in CO 2 

### concentrations between produced natural gas and pipeline quality gas applied to the

throughput of the plant. This methodology was applied to the national gas throughput using national average CO 2 

### concentrations in produced gas (3.45 percent) and transmission quality gas (1 percent). For condensate tanks, a series of

API Tankcalc (EPA 1999) simulations provide the total CO 2 

### vented per barrel of condensate throughput from fixed roof

tank flash gas for condensate gravities of API 44 degree and highe r. The ratios of emissions to throughput were used to

estimate the CO 2 

### emission factor for condensate passing through fixed roof tanks. The detailed source emission estimates

for CH 4 

### and CO 2 

### from the production sector are presented in Table A- 125 and Table A- 130, respectively.

In the processing sector, the CO 2 

### content of the natural gas remains the same as the CO 2 

### content in the

production sector for the equipment upstream of the acid gas removal unit because produced natural gas is usually only

minimally treated after being produced and then transported to natural gas processing plants via gathering pipelines. The

CO 2 

### content in gas for the remaining equipment that is downstream of the acid gas removal is the same as in pipeline

quality gas. The EPA/GRI study estimates the average CH 4 

### content of natural gas in the processing sector to be 87 percent

CH 4 

### . Consequently, the processing sector CH 4 

### emission factors were proportioned to reflect the CO 2 

### content of either

produced natural gas or pipeline quality gas using the same methodology as the production sector. The detailed source

emission estimates for CH 4 

### and CO 2 

### from the processing sector are presen ted in Table A- 126 and Table A- 131,

respectively.

For the transmission sector, CO 2 

### content in natural gas transmission pipelines was estimated for the top twenty

transmission pipeline companies in the United States (separate analyses identified the top twenty companies based on gas

throughput and total pipeline miles). The weighted average CO 2 

### content in the transmission pipeline quality gas in both

cases—total gas throughput and total miles of pipeline—was estimated to be about 1 percent. To estimate the CO 2



### emissions for the transmission sector the CH 4 

### emission factors were proportioned from the 93.4 percent CH 4 

### reported in

EPA/GRI (1996) to reflect the 1 percent CO 2 

### content found in transmission quality natural gas. The detailed source

emissions estimates for CH 4 

### and CO 2 

### for the transmission sector are presented in Table A- 127 and Table A- 132,

respectively.

The natural gas in the distribution sector of the system has the same characteristics as the natural gas in the

transmission sector. The CH 4 

### content (93.4 percent) and CO 2 

### content (1 percent) are identical due to the absence of any

further treatment between sector boundaries. Thus, the CH 4 

### emissions factors were converted to CO 2 

### emission factors

using the same methodology as discussed for the transmission sector. The detailed source emission estimates for CH 4 

### and

CO 2 

### for the distribution sector are presented in Table A- 128 and Table A- 133, respectively.

Because Partners report only CH 4 

### emission reductions to the Natural Gas STAR Program, there was no need to

adjust for the Natural Gas STAR program in the CO 2 

### emissions estimates for any of the sectors in the natural gas system.

The impact of NESHAP regulations on CO 2 

### emission reductions are not currently addressed in the CO 2 

### emission

estimates.

A-143

### Table A- 118: 2008 Data and CH 4 

### Emissions (Mg) for the Natural Gas Production Stage

Activity 2008 EPA Inventory Value s

A ctivity Data Emission Factor Emissions

North East

Gas Wells

NE - A ssociated Gas Wells 2

NE - Non-associated Gas Wells (less

Unconventional)

NE - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

Mi d -Centra l

Gas Well s

MC - A ssociated Gas Wells 2

MC - Non-associated Gas Wells

MC - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps 47,088 wells N A

174,609 wells 7 scfd/well

0 wells N A scfd/well

349 heaters 14 scfd/heater

123,972 separators 1 scfd/sep

1,130 dehydrators 22 scfd/deh y

8,868 meters 9 scfd/meter

175 compressors 269 scfd/comp

24 compressors 15,262 sc f d/comp

3 stations 8,278 scfd/station

84,210 miles 53 scfd/mile

253 completions/year 736 scf/comp

15,490 wells 2,553 scf/well

84,860 controllers 346 scfd/device

873 active pumps 249 scfd/pump

330,819 MMscf/yr 996 scf/MMsc f

371,290 MMsc f / yr 277 scf/MMsc f

0 MMbbl/yr 22 scf/bbl

0 MMbbl/yr 4 scf/bbl

0 MMHPhr 0.2 scf/HPhr

7,595 workovers/yr 2,463 scfy/w.o.

72,288 LP Gas Wells 49,756 scfy/LP well

125,452 vessels 78 scfy/vessel

84,210 miles (gathering) 310 scfy/mile

175 compressors 3,788 scfy/comp

175 compressors 8,475 scfy/comp

334,935 PRV 34 scfy/PRV

21,053 miles 672 scf/mile

72,487 wells N A

70,098 wells 7 scfd/well

12,702 wells 5 scfd/well

33,617 heaters 15 scfd/heater

36,018 separators 1 scfd/sep

12,027 dehydrators 96 scfd/deh y

113,257 meters 9 scfd/meter

9,356 compressors 282 scfd/comp

16 compressors 16,013 scfd/comp

2 stations 8,685 scfd/station

65,703 miles 56 scfd/mile

120 completions/year 772 scf/comp

7,346 wells 2,678 scf/well

128,423 controllers 363 scfd/device

11,758 active pumps 261 scfd/pump NA

8,774

N

A

35

786

173

564

330

2,575

175

31,583

4

762

206,584

1,528

6,344

1,978

­

­

-

360

69,274

189

503

13

29

220

272

NA

3,688

453

3,537

240

8,114

7,555

18,547

1,801

122

25,854

2

379

328,011

21,587



### A-144 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008Activity 2008 EPA Inventory Value s

A ctivity Data Emission Factor Emissions

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

Rocky Mountain

Gas Well s

RM - A ssociated Gas Wells 2

RM - Non-associated Gas Wells

RM - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring 1

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

Coal Bed Methane

Powder River

South Wes t

Gas Well s

SW - A ssociated Gas Wells 2 3,520,338 MMscf/yr 1,045 scf/MMsc f

3,950,997 MMscf/yr 290 scf/MMsc f

11 MMbbl/yr 22 sc f / bbl

11 MMbbl/yr 4 scf/bbl

15,483 MMHPhr 0.3 scf/HPhr

3,602 workovers/yr 2,584 scfy/w.o.

34,279 LP Gas Wells 52,203 scfy/LP well

81,662 vessels 82 scfy/vessel

65,703 miles (gathering) 325 scfy/mile

9,356 compressors 3,974 scfy/comp

9,356 compressors 8,891 scfy/comp

158,828 PRV 36 scfy/PRV

16,426 miles 705 scf/mile

14,630 wells N A

62,958 wells 36 scfd/well

25,512 wells 7 scfd/well

40,342 heaters 58 scfd/heater

44,146 separators 122 scfd/sep

12,851 dehydrators 91 scfd/deh y

102,226 meters 53 scfd/meter

9,820 compressors 267 scfd/comp

32 compressors 15,161 scfd/comp

4 stations 8,223 scfd/station

113,453 miles 53 scfd/mile

128 completions/year 731 scf/comp

7,849 wells 2,536 scf/well

129,520 controllers 344 scfd/device

15,748 active pumps 247 scfd/pump

3,761,376 MMscf/yr 989 scf/MMsc f

4,221,522 MMscf/yr 275 scf/MMsc f

13 MMbbl/yr 22 scf/bbl

13 MMbbl/yr 4 scf/bbl

16,543 MMHPhr 0.2 scf/HPhr

3,848 workovers/yr 2,447 scfy/w.o.

36,626 LP Gas Wells 49,426 scfy/LP well

97,339 vessels 78 scfy/vessel

113,453 miles (gathering) 308 scfy/mile

9,820 compressors 3,763 scfy/comp

9,820 compressors 8,418 scfy/comp

169,702 PRV 34 scfy/PRV

28,363 miles 667 scf/mile

28,486,776,948 gal produced water 2.002E-09 Gg/gallon water

drainage

55,251 wells N A 70,832

22,086

4,423

885

75,370

179

34,465

129

412

716

1,602

110

223

NA

15,802

1,244

16,321

37,757

8,209

37,908

18,430

3,411

231

42,269

2

383

313,213

27,375

71,656

22,343

5,265

1,053

76,246

181

34,866

146

673

712

1,592

111

364

57,039

NA



### A-145Activity 2008 EPA Inventory Value s

A ctivity Data Emission Factor Emissions

SW - Non-associated Gas Wells

SW - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring 1

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

West Coas t

Gas Well s

WC - A ssociated Gas Wells 2

WC - Non-associated Gas Wells

WC - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring 1

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines 27,903 wells 37 scfd/well

10,146 wells N A

10,311 heaters 59 scfd/heater

21,383 separators 125 scfd/sep

5,527 dehydrators 93 scfd/deh y

46,589 meters 54 scfd/meter

5,175 compressors 274 scfd/comp

16 compressors 15,536 scfd/comp

2 stations 8,426 scfd/station

56,981 miles 54 scfd/mile

55 completions/year 749 scf/comp

3,375 wells 2,598 scf/well

50,529 controllers 352 scfd/device

2,321 active pumps 253 scfd/pump

1,617,679 MMscf/yr 1,014 scf/MMsc f

1,815,576 MMscf/yr 282 scf/MMsc f

6 MMbbl/yr 22 scf/bbl

6 MMbbl/yr 4 scf/bbl

7,115 MMHPhr 0.2 scf/HPhr

1,655 workovers/yr 2,507 scfy/w.o.

15,752 LP Gas Wells 50,648 scfy/LP well

37,221 vessels 80 scfy/vessel

56,981 miles (gathering) 316 scfy/mile

5,175 compressors 3,856 scfy/comp

5,175 compressors 8,627 scfy/comp

72,985 PRV 35 scfy/PRV

14,245 miles 684 scf/mile

24,259 wells N A

1,693 wells 42 scfd/well

0 wells N A

1,693 heaters 67 scfd/heater

1,236 separators 142 scfd/sep

246 dehydrators 106 scfd/deh y

3,242 meters 62 scfd/meter

1,966 compressors 312 scfd/comp

8 compressors 17,728 scfd/comp

1 stations 9,615 scfd/station

16,263 miles 62 scfd/mile

2 completions/year 855 scf/comp

150 wells 2,965 scf/well

1,696 controllers 402 scfd/device

1,150 active pumps 289 scfd/pump

71,980 MMscf/yr 1,157 scf/MMsc f

80,785 MMscf/yr 321 scf/MMsc f

0 MMbbl/yr 22 scf/bbl

0 MMbbl/yr 4 scf/bbl

317 MMHPhr 0.3 scf/HPhr 7,303.98

NA

4,274.52

18,740.61

3,617.63

17,703.68

9,951.73

1,747.41

118.47

21,753.84

0.80

169

125,212

4,134

31,579

9,847

2,527

505

33,602

80

15,366

57

346

384

860

49

188

NA

506

NA

801

1,236

184

1,406

4,314

997

68

7,085

0.04

9

4,797

2,337

1,603

500

-

-

1,706



### A-146 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008Activity 2008 EPA Inventory Value s

A ctivity Data Emission Factor Emissions

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

Gulf Coas t

Gas Well s

GC - A ssociated Gas Wells 2

GC - Non-associated Gas Wells

GC - Unconventional Gas Wells

Field Separation Equipmen t

Heaters

Separators

Dehydrators

Meters/Piping

Gathering Compressor s

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Drilling and Well Completion

Completion Flaring

Well Drilling

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vent s

Condensate Tanks without Control Devices

Condensate Tanks with Control Devices

Compressor Exhaust Vente d

Gas Engines

Well Workover s

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdown s

Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upset s

Pressure Relief Valves

Mishaps

Coal Bed Methan e

Black Warrior

Offshore Platforms

Shallow water Gas Platforms (GoM and Pacific)

Deepwater Gas Platforms (GoM and Pacific) 74 workovers/yr 2,861 scfy/w.o.

701 LP Gas Wells 57,796 scfy/LP well

3,175 vessels 91 scfy/vessel

16,263 miles (gathering) 360 scfy/mile

1,966 compressors 4,400 scfy/comp

1,966 compressors 9,844 scfy/comp

3,248 PRV 40 scfy/PRV

4,066 miles 780 scf/mile

26,560 wells N A

69,394 wells 41 scfd/well

0 wells N A scfd/well

15,544 heaters 65 scfd/heater

45,661 separators 137 scfd/sep

10,080 dehydrators 102 scfd/deh y

80,993 meters 59 scfd/meter

5,621 compressors 301 scfd/comp

24 compressors 17,084 scfd/comp

3 stations 9,266 scfd/station

92,088 miles 60 scfd/mile

101 completions/year 824 scf/comp

6,156 wells 2,857 scf/well

48,229 controllers 388 scfd/device

2,290 active pumps 279 scfd/pump

2,950,362 MMscf/yr 1,115 scf/MMsc f

3,311,293 MMscf/yr 310 scf/MMsc f

32 MMbbl/yr 22 scf/bbl

32 MMbbl/yr 4 scf/bbl

12,976 MMHPhr 0.3 scf/HPhr

3,019 workovers/yr 2,757 scfy/w.o.

28,729 LP Gas Wells 55,697 scfy/LP well

71,286 vessels 88 scfy/vessel

92,088 miles (gathering) 347 scfy/mile

5,621 compressors 4,240 scfy/comp

5,621 compressors 9,487 scfy/comp

133,112 PRV 38 scfy/PRV

23,022 miles 752 scf/mile

5,026 wells 0.002 Gg/wel l

2,218 Shallow water gas

platforms 19,178 scfd/platform

39 Deepwater gas

platforms 79,452 scfd/platform 4

780

6

113

167

373

2

61

NA

19,975

N

A

7,086

44,008

7,256

33,845

11,888

2,882

195

38,662

2

339

131,429

4,486

63,337

19,749

13,479

2,696

67,395

160

30,818

120

616

459

1,027

98

333

11,687

299,058

21,783

1 Emissions are not actually 0, but too small to show at this level of precision.

2 Emissions from oil wells that produce associated gas are estimated in the Petroleum Systems model. Here the oil wells count is used as a driver only.

3 NA = not available; i.e. this data is not available from the specified source.



### A-147

### Table A- 119: 2008 Data and CH 4 

### Emissions (Mg) for the Natural Gas Processing Stage

2008 EPA Adjusted Values

Activity Activity Data Emission Factor Emissions

Plants

Recip. Compressors

Centrifugal Compressors

Compressor Exhaust

Gas Engines

Gas Turbines

A GR Vents

Kimray Pumps

Dehydrator Vents

Pneumatic Devices

Blowdowns/Venting 577

4,781

771

34,346

40,725

292

1,244,246

11,209,420

577

577 plants

compressors

compressors

MMHPhr

MMHPhr

A GR units

MMscf/yr

MMscf/yr

gas plants

gas plants 7,906

11,196

21,230

0.2

0.01

6,083

178

122

164,721

4,060 scfd/plant

scfd/comp

scfd/comp

scf/HPhr

scf/HPhr

scfd/AGR

scf/MMscf

scf/MMscf

scfy/plant

Mscfy/plant 32,069

376,275

114,997

158,762

4,471

12,506

4,260

26,242

1,831

45,119



### Table A- 120: 2008 Data and CH 4 

### Emissions (Mg) for the Na tural Gas Transmission Stage

Activity 2008 EPA Adjusted Values

Activity Data Emission Factor Emissions

Pipeline Leaks

Compressor Stations (Transmission)

Station

Recip Compressor

Centrifugal Compressor

Compressor Stations (Storage)

Station

Recip Compressor

Centrifugal Compressor

Wells (Storage)

M&R (Trans. Co. Interconnect)

M& R (Farm Taps + Direct Sales)

Dehydrator vents (Transmission)

Dehydrator vents (Storage)

Compressor Exhaus t

Engines (Transmission)

Turbines (Transmission)

Engines (Storage)

Turbines (Storage)

Generators (Engines)

Generators (Turbines)

Pneumatic Devices Trans + Stor

Pneumatic Devices Trans

Pneumatic Devices Storage

Routine Maintenance/Upset s

Pipeline venting

Station Venting Trans + Storage

Station Venting Transmission

Station Venting Storage

LNG Storag e

LNG Stations

LNG Reciprocating Compressors

LNG Centrifugal Compressors

LNG Compressor Exhaus t

LNG Engines

LNG Turbines

LNG Station Venting

LNG Import Terminal s

LNG Stations

LNG Reciprocating Compressors

LNG Centrifugal Compressors

LNG Compressor Exhaus t

LNG Engines 294,488 miles 2 Scfd/ mile

1,748 Stations 8,778 Scfd/station

7,028 Compressors 15,205 Scfd/ comp

705 Compressors 30,305 Scfd/ comp

400 Stations 21,507 Scfd/ comp

1,178 Compressors 21,116 Sc f d/ comp

116 Compressors 30,573 Scfd/ comp

18,673 Stations 115 Scfd/ comp

2,621 Stations 3,984 scfd/station

77,729 Stations 31 scfd/station

1,114,305 MMscf/Year 94 scf/MMsc f

2,074,894 MMscf/Year 117 scf/MMsc f

46,332 MMHPhr 0.2 scf/HPhr

11,055 MMHPhr 0.01 scf/HPhr

5,106 MMHPhr 0.2 scf/HPhr

1,794 MMHPhr 0 scf/HPhr

2,267 MMHPhr 0 scf/HPhr

27 MMHPhr 0 sc f / HPhr

68,809 Devices 162,197 Scfy/device

15,763 Devices 162,197 Scfy/device

294,488 Miles 32 Mscfy/mile

1,748 Compressor

Stations 4,359 Mscf y/station

400 Compressor

Stations 4,359 Mscf y/station

70 Stations 21,507 scfd/station

270 Compressors 21,116 scfd/comp

64 Compressors 30,573 scfd/comp

718 MMHPhr 0.2 scf/HPhr

113 MMHPhr 0.01 scf/HPhr

70 Stations 4,359 Mscfy/station

7 Stations 21,507 scfd/station

34 Compressors 21,116 scfd/comp

6 Compressors 30,573 scfd/comp

1,496 MMHPhr 0.2 scf/HPhr 3,217

107,873

751,258

150,174

60,546

174,866

24,931

15,030

73,420

17,049

2,011

4,683

214,167

1,214

23,603

197

10,480

3

214,952

49,242

179,514

146,761

33,620

10,623

40,147

13,766

3,320

12

5,899

1,058

5,047

1,290

6,913



### A-148 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008LNG Turbines 358 MMHPhr 0.01 scf/HPhr 39

LNG Station Venting 7 Stations 4,359 Mscfy/station 588



### Table A- 121: 2008 Data and CH 4 

### Emissions (Mg) for the Natu ral Gas Distribution Stage

Activity 2008 EPA Adjusted Value s

Activity Data Emission Factor Emissions

Pipeline Leak s

Mains

—

Cast Iron 36,462 miles 239 Mscf/mile-yr 167,628

Mains

—

Unprotected steel 69,374 miles 110 Mscf/mile-yr 147,229

Mains

—

Protected steel 479,502 miles 3 Mscf/mile-yr 28,324

Mains

—

Plasti c 603,377 miles 10 Mscf/mile-yr 115,164

Services

—

Unprotected steel 5,388,623 services 2 Mscf/service 176,514

Services Protect ed steel 15,456,866 services 0.2 Mscf/service 52,543

Services

—

Plastic 41,573,069 services 0.01 Mscf/service 7,445

Services

—

Copper

Meter/Regulator (City Gates) 1,140,738 services 0.3 Mscf/service 5,588

M&R >300 4,033 stations 180 scfh/station 122,342

M&R 100-300 14,718 stations 96 scfh/station 237,389

M&R <100 7,867 stations 4 scfh/station 5,720

Reg >300 4,409 stations 162 scfh/station 120,441

R-Vault >300 2,590 stations 1 scfh/station 568

Reg 100-300 13,339 stations 41 scfh/station 91,145

R-Vault 100-300 5,993 stations 0.2 scfh/station 182

Reg 40-100 40,028 stations 1 scfh/station 7,024

R-Vault 40-100 35,497 stations 0.1 scfh/station 518

Reg <40

Customer Meter s 16,973 stations 0.1 scfh/station 381

Residential 41,549,008 outdr meters 143 scfy/meter 114,650

Commercial/Industry

Routine Maintenance 4,345,918 meters 48 scfy/meter 4,009

Pressure Relief Valve Releases 1,188,714 mile main 0.1 Mscf/mile 1,145

Pipeline Blowdown

Upse t s 1,346,158 miles 0.1 Mscfy/mile 2,645

Mishaps (Dig-ins) 1,346,158 miles 2 mscfy/mile 41,224



### A-149Table A- 122: Key Activity Data DriversVariable Units1990199520022003 20042005 2006 2007 2008Transmission Pipelines Lengthmiles291,990296,947303,541 301,827 303,095 300,542 300,321 300,996 294,488WellsNE—Associated Gas Wells*# wells68,26166,10252,928 47,803 47,412 46,47147,03446,64647,088NE—Non-associated Gas Wells*# wells124,241129,789154,590 156,320 155,257 158,238 164,322 172,493 174,609MC—Associated Gas Wells*# wells64,37972,48365,786 65,864 65,902 65,65265,90369,23472,487MC—Non-associated Gas Wells*# wells53,94065,58567,861 70,377 72,809 71,37973,91480,65082,800RM—Associated Gas Wells*# wells13,74913,74512,446 12,495 12,723 13,25913,43712,01214,630RM—Non-associated Gas Wells*# wells24,33932,66872,438 71,239 70,770 72,57975,17070,53288,470SW—Associated Gas Wells*# wells69,33959,95460,623 60,31559,38154,78154,55055,25155,251SW—Non-associated Gas Wells*# wells24,21727,39235,025 36,648 37,219 34,24735,41738,04938,049WC—Associated Gas Wells*# wells20,67219,10922,503 22,263 22,584 21,56222,18922,11024,259WC—Non-associated Gas Wells*# wells1,2921,1141,415 1,459 1,388 1,424 1,503 1,506 1,693GC—Associated Gas Wells*# wells36,27934,79229,880 28,078 27,675 28,09027,31926,23426,560GC—Non-associated Gas Wells*# wells41,753PlatformsGulf of Mexico and Pacific OCS Off-shore41,97853,198 54,245 54,544 57,60060,71568,18869,394Platforms# platforms3,941GoM and Pacific OCS Deep Water3,9784051 400339323908391238373762Platforms# platforms172344 46 50 59 6763 65Gas Plants# gas plants761675590 574 572 566 571 574 577Distribution Services# of services47,883,08354,644,03358,876,416 58,537,395 61,089,889 58,556,335 62,255,435 63,524,388 63,559,296Steel—Unprotected# of services7,633,5266,151,6535,186,134 4,840,347 4,791,652 5,308,375 5,642,470 5,448,804 5,388,623Steel—Protected# of services19,781,58121,002,45517,778,463 17,258,710 18,147,587 15,883,423 15,732,037 15,756,048 15,456,866Plastic# of services18,879,86526,044,54534,547,274 35,071,961 36,811,107 36,152,277 39,632,313 41,092,515 41,573,069Copper# of services1,588,1111,445,3801,364,545 1,366,377 1,339,543 1,212,260 1,248,615 1,277,021 1,140,738Distribution Mainsmiles944,1571,001,7061,133,625 1,104,683 1,151,995 1,093,909 1,209,419 1,198,585 1,188,714Cast Ironmiles58,29250,62542,025 41,091 40,600 37,37136,97737,66936,462Steel—Unprotectedmiles108,94194,05878,119 74,042 75,859 69,29171,73869,52569,374Steel—Protectedmiles465,538503,288480,982 483,782 495,861 461,459 481,811 489,815 479,502Plasticmiles311,386353,735532,499 505,768 539,675 525,788 618,893 601,575 603,377*NEMS (National Energy Modeling System)projects the production, imports, conversion, consumption,and prices of energy, subject to assumptions on macroeconomic andfinancial factors, world energy markets, resource availability andcosts, behavioral and technological choice criteria, cost and performance characteristics of energy technologies, and demographicsA-150 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008

### Table A- 123: CH 4 

### Reductions Derived from the Natural Gas STAR Program (Gg)

Process 1992* 1995 2002 2003 2004 2005 2006 2007 2008

Production - 75 439 615 1,002 1,425 1,469 1,857 2,227



### Processing - 5 38 68 65 129 140 139 145



### Transmission and Storage

- 121 344 330 416 512 505 487 471



### Distribution - 19 151 116 100 35 48 34 26



### Total - 220 972 1,130 1,583 2,101 2,162 2,518 2,869

*Reductions are relative to 1992; theref ore, there are zero reductionsin 1992.

Note: These reductions will not match the Natural Gas STAR prog ram reductions. These numbers are adjusted for reductions prior to the 1992 base year, and do not

include a sunsetting period. Totals may not sum due to independent rounding.



### Table A- 124: CH 4 

### Reductions Derived from NESHAP Regulations (Gg)

Process 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

Production 24.0 25.4 27.6 28.6 28.6 28.4 28.9 30.5 31.6 32.8

Processing

Transmission and Storage

Distribution 12.7

N A

N

A 12.9

NA

NA 13.2

NA

NA 12.7

NA

NA 12.8

NA

NA 12.5

NA

NA 12.1

NA

NA 12.4

NA

NA 12.9

NA

NA 13.9

N

A

N

A

Total 36.7 38.3 40.8 41.3 41.4 40.9 41.0 43.0 44.5 46.7

NA Not applicable

Note: NESHAP regulations went into effect in 1999. Totals may not sum due to independent rounding.



### Table A- 125: CH 4 

### Emission Estimates from the Natural Gas Production Stage Exluding Reductions from the Natural Gas

STAR Program and NESHAP regulations (Gg)

Activity 1990 1992

Normal Fugitives

Gas Wells

Non- A

ssociated Gas Wells (less

conventional)

Unconventional Gas Wells

Field Separation Equipment

Heaters

Separators

Dehydrators

Meter/ Piping

Gathering Compressors

Small Reciprocating Comp.

Large Reciprocating Comp.

Large Reciprocating Stations

Pipeline Leaks

Vented and Combusted

Drilling and Well Completion

Completion Flaring

Well Drilling

Coal Bed Methane

Powder River

Black Warrior

Normal Operations

Pneumatic Device Vents

Chemical Injection Pumps

Kimray Pumps

Dehydrator Vents

Condensate Tank Vents

Condensate Tanks without

Control Device

Condensate Tanks with Control

Device

Compressor Exhaust Vented

Gas Engines

Well Workovers

Gas Wells

Well Clean Ups (LP Gas Wells)

Blowdowns 30.82

0.01

12.57

43.83

14.75

43.61

30.22

7.50

0.51

98.03

0.01

0.74

0.04

2.72

569.76

26.89

131.82

41.10

23.59

4.72

119.06

0.56

106.80 31.68

0.02

13.28

44.16

15.76

44.95

32.15

8.56

0.58

102.22

0.01

0.54

0.47

4.84

607.88

29.38

140.65

43.86

21.69

4.34

125.48

0.58

111.49 1995 2002 2003 2004 2005 2006 2007 2008

37.42

0.04

16.48

54.79

17.89

54.89

38.27

9.80

0.66

114.49

0.01

0.53

1.48

6.25

697.61

35.04

159.45

49.72

20.22

4.04

151.43

0.64

122.33 51.07 50.29 50.09 49.40 50.87 52.01 56.05

0.67 0.85 0.98 1.21 1.33 1.52 1.70

26.44 26.60 26.67 26.94 28.00 28.44 32.05

84.15 85.03 85.25 86.52 90.23 94.19 102.77

23.28 23.62 23.73 23.96 24.90 26.20 27.55

81.96 82.73 83.08 83.81 87.15 90.37 98.98

52.53 53.52 53.99 53.89 56.03 58.55 63.46

12.62 12.48 12.61 12.60 12.58 12.56 13.41

0.86 0.85 0.86 0.85 0.85 0.85 0.91

145.52 145.56 147.60 148.53 152.90 158.22 167.21

0.01 0.01 0.01 0.01 0.01 0.01 0.01

1.01 1.17 1.37 1.61 1.88 2.00 2.04

47.17 46.85 44.74 46.37 56.55 54.12 57.04

7.81 8.54 9.22 9.88 10.45 11.08 11.69

932.14 937.52 955.82 955.56 990.34 1,031.91 1,109.25

49.42 51.28 51.80 51.93 53.85 54.98 61.45

207.39 210.19 211.38 213.42 221.79 233.31 245.35

64.67 65.54 65.91 66.55 69.16 72.75 76.50

24.43 23.59 22.54 23.59 25.90 25.69 25.69

4.89 4.72 4.51 4.72 5.18 5.14 5.14

208.50 212.13 214.62 215.27 223.88 235.54 254.32

0.82 0.82 0.84 0.84 0.87 0.92 0.97

157.67 156.89 160.77 162.03 167.93 176.14 185.57



### A-151Vessel BD

Pipeline BD

Compressor BD

Compressor Starts

Upsets

Pressure Relief Valves

Mishaps

Offshore

Offshore water Gas Platforms

(GoM & Pacific)

Deepwater Gas Platforms (GoM &

Pacific) 0.36

1.56

1.17

2.61

0.34

0.85

290.49

5.21

1,696 Total 1,612 0.38

1.63

1.24

2.78

0.35

0.88

297.77

5.94 0.42

1.82

1.48

3.31

0.39

0.99

307.32

7.40 0.55 0.55 0.56 0.56 0.58

2.32 2.32 2.35 2.37 2.44

2.03 2.07 2.08 2.08 2.16

4.54 4.62 4.66 4.66 4.84

0.50 0.50 0.51 0.51 0.53

1.25 1.25 1.27 1.28 1.32

331.99 330.76 324.49 321.73 321.34

15.10 15.93 17.31 20.43 23.20 0.61 0.65

2.52 2.66

2.26 2.45

5.06 5.48

0.56 0.59

1.36 1.44

305.09 299.06

21.10 21.78

1,917 2,543 2,559 2,582 2,593 2,689 2,765 2,933

Note: Totals may not sum due to independent rounding.



### Table A- 126: CH 4 

### Emission Estimates from the Nat ural Gas Processing Plants Exluding Reductions from the Natural Gas

STAR Program and NESHAP regulations (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Normal Fugitives

Plants 42.30 40.68 37.52 32.79 31.90 31.79 31.46 31.74 31.90 32.07

Reciprocating

Compressors 324.94 324.74 338.42 344.69 347.39 338.24 327.87 337.12 348.25 376.28

Centrifugal Compressors 99.31 99.25 103.43 105.34 106.17 103.37 100.20 103.03 106.43 115.00

Vented and Combusted

Normal Operations

Compressor Exhaust

Gas Engines 137.10 137.02 142.79 145.43 146.57 142.71 138.34 142.24 146.94 158.76

Gas Turbines 3.86 3.86 4.02 4.10 4.13 4.02 3.90 4.01 4.14 4.47

A GR Vents 16.49 15.87 14.63 12.79 12.44 12.40 12.27 12.38 12.44 12.51

Kimray Pumps 3.68 3.68 3.83 3.90 3.93 3.83 3.71 3.82 3.94 4.26

Dehydrator Vents 22.66 22.65 23.60 24.04 24.23 23.59 22.87 23.51 24.29 26.24

Pneumatic Devices 2.41 2.32 2.14 1.87 1.82 1.81 1.80 1.81 1.82 1.83

Routine Maintenance

Blowdowns/Venting 59.51 57.24 52.78 46.14 44.88 44.73 44.26 44.65 44.88 45.12

Total 712 707 723 721 723 706 687 704 725 777

Note: Totals may not sum due to independent rounding.



### A-152 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008

### Table A- 127: CH 4 

### Emission Estimates from the Natural Gas Transmi ssion and Storage Exluding Reductions from the

Natural Gas STAR Program and NESHAP regulations (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Fugitives

Pipelines Leaks 3.19 3.18 3.24 3.32 3.30 3.31 3.28 3.28 3.29 3.22

Compressor Stations

(Transmission)

Station 106.96 106.77 108.77 111.19 110.56 111.03 110.09 110.01 110.26 107.87

Recip Compressor 744.89 743.55 757.53 774.35 769.98 773.22 766.70 766.14 767.86 751.26

Centrifugal Compressor 148.90 148.63 151.43 154.79 153.92 154.56 153.26 153.15 153.49 150.17

Compressor Stations

(Storage)

Station 54.64 58.36 60.35 60.83 63.20 60.58 60.06 54.36 58.70 60.55

Recip Compressor 157.80 168.48 174.27 175.76 182.59 175.01 173.53 157.05 169.52 174.87

Centrifugal

Compressor 22.35 23.86 24.72 24.93 26.01 24.93 24.72 22.35 24.07 24.93

Wells (Storage) 13.56 14.49 14.98 15.10 15.69 15.04 14.91 13.49 14.57 15.03

M&R (Trans. Co.

Interconnect) 72.80 72.67 74.03 75.68 75.25 75.57 74.93 74.87 75.04 73.42

M&R (Farm Taps + Direct

Sales) 16.90 16.87 17.19 17.57 17.47 17.55 17.40 17.39 17.43 17.05

Vented and Combusted

Normal Operation

Dehydrator Vents

(Transmission) 1.99 1.99 2.03 2.07 2.06 2.07 2.05 2.05 2.06 2.01

Dehydrator Vents

(Storage) 4.23 4.51 4.67 4.71 4.89 4.69 4.65 4.20 4.54 4.68

Compressor Exhaust

Engines (Transmission) 176.92 186.65 204.91 212.29 205.55 206.59 203.10 200.09 212.66 214.17

Turbines (Transmission) 1.00 1.06 1.16 1.20 1.16 1.17 1.15 1.13 1.21 1.21

Engines (Storage) 21.30 22.75 23.53 23.72 24.64 23.62 23.41 21.19 22.88 23.60

Turbines (Storage) 0.18 0.19 0.20 0.20 0.21 0.20 0.20 0.18 0.19 0.20

Generators (Engines) 8.66 9.13 10.03 10.39 10.06 10.11 9.94 9.79 10.41 10.48

Generators (Turbines) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Pneumatic Devices

Trans+Stor

Pneumatic Devices Trans 213.13 212.75 216.75 221.56 220.31 221.23 219.37 219.21 219.70 214.95

Pneumatic Devices Storage 44.44 47.46 49.09 49.48 51.40 49.27 48.85 44.21 47.74 49.24

Routine Maintenance/Upsets

Pipeline Venting 177.99 177.67 181.01 185.03 183.99 184.76 183.20 183.07 183.48 179.51

Station venting

Trans+Storage

Station Venting

Transmission 145.52 145.26 147.99 151.27 150.42 151.05 149.78 149.67 150.00 146.76

Station Venting Storage 30.34 32.41 33.51 33.78 35.10 33.64 33.35 30.18 32.59 33.62

LNG Storage

LNG Stations 9.24 9.45 9.77 10.52 10.62 10.62 10.62 10.62 10.62 10.62

LNG Reciprocating

Compressors 34.50 35.37 36.67 39.71 40.15 40.15 40.15 40.15 40.15 40.15

LNG Centrifugal

Compressors 11.78 12.09 12.55 13.61 13.77 13.77 13.77 13.77 13.77 13.77

LNG Compressor Exhaust

LNG Engines 3.21 3.23 3.25 3.31 3.32 3.32 3.32 3.32 3.32 3.32

LNG Turbines 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

LNG Station Venting 5.13 5.25 5.43 5.84 5.90 5.90 5.90 5.90 5.90 5.90

LNG Import Terminals

LNG Stations 0.21 0.21 0.21 0.32 0.42 0.42 0.42 0.42 0.42 1.06

LNG Reciprocating

Compressors 1.01 1.01 1.01 1.51 2.02 2.02 2.02 2.02 2.02 5.05

LNG Centrifugal

Compressors 0.26 0.26 0.26 0.39 0.52 0.52 0.52 0.52 0.52 1.29

LNG Compressor Exhaust

LNG Engines 1.74 0.96 0.49 4.52 9.83 12.57 12.18 11.28 14.81 6.91

LNG Turbines 1 0.01 0.00 0.00 0.03 0.06 0.07 0.07 0.07 0.09 0.04



### A-153LNG Station Venting 0.12 0.12 0.12 0.18 0.24 0.24 0.24 0.24 0.24 0.59

Total 2,235 2,267 2,331 2,389 2,395 2,389 2,367 2,325 2,374 2,348

1 Emissions are not actually 0, but too small to show at this level of precision.

Note: Totals may not sum due to independent rounding.



### Table A- 128: CH 4 

### Emission Estimates from the Natural Gas Distributi on Stage Exluding Reductions from the Natural Gas

STAR Program (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Pipeline Leaks

Mains—Cast Iron 267.99 243.28 232.74 193.20 188.91 186.65 171.81 170.00 173.18 167.63

Mains—Unprotected steel 231.20 211.42 199.62 165.79 157.14 160.99 147.05 152.25 147.55 147.23

Mains—Protected steel 27.50 27.71 29.73 28.41 28.58 29.29 27.26 28.46 28.93 28.32

Mains—Plastic 59.43 51.02 67.52 101.64 96.53 103.01 100.36 118.13 114.82 115.16

Services—Unprotected steel 250.05 233.84 201.51 169.88 158.55 156.96 173.89 184.83 178.49 176.51

Services Protected steel 67.24 67.11 71.39 60.43 58.67 61.69 53.99 53.48 53.56 52.54

Services—Plastic 3.38 3.71 4.66 6.19 6.28 6.59 6.47 7.10 7.36 7.44

Services—Copper 7.78 7.68 7.08 6.68 6.69 6.56 5.94 6.12 6.01 5.59

Meter/Regulator (City Gates)

M&R >300 110.41 117.93 121.96 122.92 127.71 122.42 121.36 109.84 118.61 122.34

M&R 100-300 214.25 228.82 236.64 238.52 247.81 237.54 235.49 213.13 230.15 237.39

M&R <100 5.16 5.51 5.70 5.75 5.97 5.72 5.67 5.14 5.55 5.72

Reg >300 108.70 116.09 120.06 121.01 125.73 120.52 119.48 108.13 116.77 120.44

R-Vault >300 0.51 0.55 0.57 0.57 0.59 0.57 0.56 0.51 0.55 0.57

Reg 100-300 82.26 87.86 90.86 91.58 95.15 91.20 90.42 81.83 88.37 91.15

R-Vault 100-300 0.16 0.18 0.18 0.18 0.19 0.18 0.18 0.16 0.18 0.18

Reg 40-100 6.34 6.77 7.00 7.06 7.33 7.03 6.97 6.31 6.81 7.02

R-Vault 40-100 0.47 0.50 0.52 0.52 0.54 0.52 0.51 0.47 0.50 0.52

Reg <40 0.34 0.37 0.38 0.38 0.40 0.38 0.38 0.34 0.37 0.38

Customer Meters

Residential 103.47 110.51 114.29 115.20 119.68 114.72 113.73 102.93 111.15 114.65

Commercial/Industry 3.97 4.25 4.78 4.38 4.25 4.27 3.95 3.85 3.97 4.01

Routine Maintenance

Pressure Relief Valve Releases 0.91 0.86 0.96 1.09 1.06 1.11 1.05 1.16 1.15 1.14

Pipeline Blowdown 2.39 2.55 2.64 2.66 2.76 2.65 2.62 2.37 2.56 2.64

Upsets

41.42 43.03 41.25 40.89 37.01 39.97 41.22

Mishaps (Dig-ins) 37.20 39.74 41.09

Total 1,591 1,568 1,562 1,485 1,484 1,462 1,430 1,394 1,437 1,450

Note: Totals may not sum due to independent rounding.



### Table A- 129: U.S. Production Sector CO 2 

### Content in Natural Gas by NEMS Region and Natural Gas Well type

Well Types North East Mid-Central Gul f Coast U.S. Region

South West Rocky Mountain West Coast Lower-48 States

Conventional 0.92% 0.79% 2.17% 3.81% 7.95% 0.16% 3.41%

Un-conventional 7.42% 0.31% 0.23% N A 0.64% N A

4.83%

A ll types 3.04% 0.79% 2.17% 3.81% 7.58% 0.16% 3.45%



### Table A- 130: CO 2 

### Emission Estimates from the Na tural Gas Production Stage (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Normal Fugitives

Gas Wells

Associated Gas Wells 3.56 3.57 4.25 6.67 6.44 6.27 6.04 6.18 5.87 7.01

Unconventional Gas Wells 2 0.00 0.00 0.00 0.01 0.02 0.02 0.03 0.03 0.03 0.03

Field Separation Equipment

Heaters 1.86 1.91 2.32 4.42 4.39 4.38 4.44 4.61 4.48 5.35

Separators 6.04 5.97 7.17 12.55 12.56 12.56 12.70 13.20 13.16 15.21

Dehydrators 1.50 1.54 1.73 2.81 2.81 2.79 2.83 2.94 2.93 3.30

Meter/ Piping 5.85 5.85 6.95 12.12 12.12 12.11 12.23 12.69 12.57 14.61

Gathering Compressors

Small Reciprocating Comp. 2.95 2.98 3.57 6.13 6.15 6.16 6.18 6.41 6.38 7.38

Large Reciprocating Comp. 0.69 0.91 1.02 1.40 1.40 1.40 1.40 1.40 1.40 1.62

Large Reciprocating Stations 0.05 0.06 0.07 0.09 0.09 0.09 0.09 0.09 0.09 0.11

Pipeline Leaks 10.75 10.85 11.99 17 18 17 18 18 18 20

Vented and Combusted



### A-154 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - - Drilling and Well Completion

Completion Flaring 2 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00

Well Drilling 0.07 0.05 0.05 0.11 0.13 0.15 0.18 0. 21 0.22 0.23

Coal Bed Methane

Powder River 1

- ­ -

Black Warrior 1

- ­ - Normal Operations

Pneumatic Device Vents 58.49 60.24 69.38 114 114 114 115 119 119 136

Chemical Injection Pumps 2.95 3.11 3.75 7.00 7.09 7.08 7.19 7.45 7.20 8.66

Kimray Pumps 13.41 13.71 15.43 24.94 24.93 24.78 25.18 26.12 26.05 29.32

Dehydrator Vents 4.18 4.28 4.81 7.78 7.77 7.73 7.85 8.15 8.12 9.14

Condensate Tank Vents

Condensate Tanks without

Control Device 10.25 9.43 8.79 10.62 10.25 9.79 10.25 11.26 11.17 11.17

Condensate Tanks with Control

Device 2.05 1.89 1.76 2.12 2.05 1.96 2.05 2.25 2.23 2.23

Compressor Exhaust Vented

Gas Engines 1

- ­ -

Well Workovers

- ­ -

Gas Wells 0.06 0.06 0.06 0.09 0.09 0.09 0.09 0.10 0.10 0.11

Well Clean Ups (LP Gas Wells) 10.64 10.89 12.02 17.86 17.95 17.92 18.15 18.84 19.13 21.11

Blowdowns

Vessel BD 0.04 0.04 0.04 0.06 0.06 0.06 0.07 0.07 0.07 0.08

Pipeline BD 0.17 0.17 0.19 0.28 0.28 0.28 0.28 0.29 0.29 0.32

Compressor BD 0.11 0.12 0.14 0.24 0.24 0.24 0.24 0.25 0.25 0.28

Compressor Starts 0.25 0.26 0.31 0.53 0.53 0.53 0.53 0.55 0.55 0.64

Upsets

Pressure Relief Valves 0.03 0.03 0.04 0.06 0.06 0.06 0.06 0.06 0.06 0.07

Mishaps 0.09 0.09 0.10 0.15 0.15 0.15 0.15 0.16 0.16 0.17

Flaring Emissions - Onshore 9,093 10,172 17,168 6,001 5,936 5,828 7,200 7,812 9,104 7,838

Offshore

Offshore water Gas Platforms (GoM

& Pacific) 1.47 1.51 1.56 1.69 1.68 1.65 1.63 1.63 1.55 1.52

Deepwater Gas Platforms (GoM &

Pacific) 0.03 0.03 0.04 0.08 0.08 0.09 0.10 0.12 0.11 0.11

Flaring Emissions - Offshore 230 163 197 211 155 165 181 146 160 361

Total 9,461 10,475 17,523 6,463 6,343 6,243 7,633 8,221 9,525 8,495

1 Energy use CO 2 emissions not estimated to avoid double counting.

2 Emissions are not actually 0, but too small to show at this level of precision

. Note: Totals may not sum due to independent rounding.



### Table A- 131: CO 2 

### Emission Estimates from the Na tural Gas Processing Plants (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Normal Fugitives

Plants

– Before CO 2 removal 2.56 2.46 2.27 1.98 1.93 1.92 1.90 1.92 1.93 1.94

Plants

– A fter CO 2 removal 0.57 0.55 0.50 0.44 0.43 0.43 0.42 0.43 0.43 0.43

Reciprocating Compressors

– Before CO 2 removal 19.67 19.66 20.45 20.86 21.03 20.47 19.85 20.41 21.08 22.78

Reciprocating Compressors

– After CO 2 removal 4.37 4.36 4.55 4.63 4.67 4.55 4.41 4.53 4.68 5.06

Centrifugal Compressors

– Before CO 2 removal 6.01 6.01 6.26 6.38 6.43 6.26 6.07 6.24 6.44 6.96

Centrifugal Compressors

– After CO 2 removal 1.33 1.33 1.39 1.42 1.43 1.39 1.35 1.38 1.43 1.55

Vented and Combusted

Normal Operations

Compressor Exhaust

Gas Engines 1

- - - Gas Turbines 1

- ­ -

A GR Vents 27,708 26,652 24,577 23,022 21,958 21,737 21,694 21,161 21,144 21,328

Kimray Pumps 0.39 0.39 0.41 0.42 0.42 0.41 0.40 0.41 0.42 0.46

Dehydrator Vents 2.42 2.42 2.52 2.57 2.59 2.52 2.45 2.51 2.60 2.81

Pneumatic Devices 0.29 0.27 0.25 0.22 0.22 0.21 0.21 0.21 0.22 0.22

Routine Maintenance



### A-155- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - -

- - - - - - - Blowdowns/Venting 6.36 6.12 5.64 4.93 4.80 4.78 4.73 4.78 4.80 4.83

Total 27,752 26,696 24,621 23,066 22,002 21,779 21,736 21,204 21,188 21,375

1 Energy use CO 2 emissions not estimated to avoid double counting.

Note: Totals may not sum due to independent rounding.



### Table A- 132: CO 2 

### Emission Estimates from the Natura l Gas Transmission and Storage (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Fugitives

Pipelines Leaks 0.09 0.09 0.09 0.10 0.10 0.10 0.09 0.09 0.09 0.09

Compressor Stations (Transmission)

Station 3.09 3.08 3.14 3.21 3.19 3.20 3.18 3.17 3.18 3.11

Recip Compressor 21.49 21.45 21.85 22.34 22.21 22.30 22.12 22.10 22.15 21.67

Centrifugal Compressor 4.30 4.29 4.37 4.47 4.44 4.46 4.42 4.42 4.43 4.33

Compressor Stations (Storage)

Station 1.58 1.68 1.74 1.75 1.82 1.75 1.73 1.57 1.69 1.75

Recip Compressor 4.55 4.86 5.03 5.07 5.27 5.05 5. 01 4.53 4.89 5.04

Centrifugal Compressor 0.64 0.69 0.71 0.72 0.75 0.72 0.71 0.64 0.69 0.72

Wells (Storage) 0.39 0.42 0.43 0.44 0.45 0.43 0.43 0.39 0.42 0.43

M&R (Trans. Co. Interconnect) 2.10 2.10 2.14 2.18 2.17 2.18 2.16 2.16 2.16 2.12

M&R (Farm Taps + Direct Sales) 0.49 0.49 0.50 0.51 0.50 0.51 0.50 0.50 0.50 0.49

Vented and Combusted

Normal Operation

Dehydrator Vents (Transmission) 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 0.06 .06

Dehydrator Vents (Storage) 0.12 0.13 0.13 0.14 0.14 0.14 0.13 0.12 0.13 .14

Compressor Exhaust

Engines (Transmission) 1

- - - Turbines (Transmission) 1

- - - Engines (Storage) 1

- - - Turbines (Storage) 1

- - - Generators (Engines) 1

- - - Generators (Turbines) 1

- - - Pneumatic Devices Trans+Stor

Pneumatic Devices Trans 6.15 6.14 6.25 6.39 6.35 6.38 6.33 6.32 6.34 6.20

Pneumatic Devices Storage 1.28 1.37 1.42 1.43 1.48 1.42 1.41 1.28 1.38 1.42

Routine Maintenance/Upsets

Pipeline Venting 5.13 5.13 5.22 5.34 5.31 5.33 5.28 5.28 5.29 5.18

Station venting Trans+Storage

Station Venting Transmission 4.20 4.19 4.27 4.36 4.34 4.36 4.32 4.32 4.33 4.23

Station Venting Storage 0.88 0.93 0.97 0.97 1.01 0.97 0.96 0.87 0.94 0.97

LNG Storage

LNG Stations 0.31 0.32 0.33 0.35 0.36 0.36 0.36 0.36 0.36 0.36

LNG Reciprocating Compressors 1.16 1.18 1.23 1.33 1.34 1.34 1.34 1.34 1.34 1.34

LNG Centrifugal Compressors 0.39 0.41 0.42 0.46 0.46 0.46 0.46 0.46 0.46 0.46

LNG Compressor Exhaust

LNG Engines 1

- - - LNG Turbines 1

- - - LNG Station Venting 0.17 0.18 0.18 0.20 0.20 0.20 0.20 0.20 0.20 0.20

LNG Import Terminals

LNG Stations 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.04

LNG Reciprocating Compressors 0.03 0.03 0.03 0.05 0.07 0.07 0.07 0.07 0.07 0.17

LNG Centrifugal Compressors 0.01 0.01 0.01 0.01 0.02 0.02 0.02 0.02 0.02 0.04

LNG Compressor Exhaust

LNG Engines 1

- - - LNG Turbines 1

- - - LNG Station Venting 2 0.00 0.00 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.02

Total 59 59 61 62 62 62 61 60 61 61

1 Energy use CO 2 emissions not estimated to avoid double counting.

2 Emissions are not actually 0, but too small to show at this level of precision.

Note: Totals may not sum due to independent rounding.



### Table A- 133: CO 2 

### Emission Estimates from the Natu ral Gas Distribution Stage (Gg)

Activity 1990 1992 1995 2002 2003 2004 2005 2006 2007 2008

Pipeline Leaks

Mains—Cast Iron 7.73 7.02 6.71 5.57 5.45 5.38 4.96 4.90 5.00 4.84

Mains—Unprotected steel 6.67 6.10 5.76 4.78 4.53 4.64 4.24 4.39 4.26 4.25



### A-156 Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2008Mains—Protected steel 0.79 0.80 0.86 0.82 0.82 0.84 0.79 0.82 0.83 0.82

Mains—Plastic 1.71 1.47 1.95 2.93 2.78 2.97 2.89 3.41 3.31 3.32

Total Pipeline Miles

6.75 5.81 4.90 4.57 4.53 5.02 5.33 5.15 5.09

Services Protected steel 1.94 Services—Unprotected steel 7.21

1.94 2.06 1.74 1.69 1.78 1.56 1.54 1.54 1.52

Services—Plastic 0.10 0.11 0.13 0.18 0.18 0.19 0.19 0.20 0.21 0.21

Services—Copper 0.22 0.22 0.20 0.19 0.19 0.19 0.17 0.18 0.17 0.16

Meter/Regulator (City Gates)

M&R >300 3.18 3.40 3.52 3.55 3.68 3.53 3.50 3.17 3.42 3.53

M&R 100-300 6.18 6.60 6.83 6.88 7.15 6.85 6.79 6.15 6.64 6.85

M&R <100 0.15 0.16 0.16 0.17 0.17 0.17 0.16 0.15 0.16 0.17

Reg >300 3.14 3.35 3.46 3.49 3.63 3.48 3.45 3.12 3.37 3.47

R-Vault >300 0.01 0.02 0.02 0.02 0.02 0.02 0.02 0.01 0.02 0.02

Reg 100-300 2.37 2.53 2.62 2.64 2.74 2.63 2.61 2.36 2.55 2.63

R-Vault 100-3001 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.01 0.01

Reg 40-100 0.18 0.20 0.20 0.20 0.21 0.20 0.20 0.18 0.20 0.20

R-Vault 40-100 0.01 0.01 0.01 0.02 0.02 0.01 0.01 0.01 0.01 0.01

Reg <40 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01

Customer Meters

3.19 3.30 3.32 3.45 3.31 3.28 2.97 3.21 3.31

Commercial/Industry 0.11 Residential 2.98

0.12 0.14 0.13 0.12 0.12 0.11 0.11 0.11 0.12

Routine Maintenance

Pressure Relief Valve Releases 0.03 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03

Pipeline Blowdown 0.07 0.07 0.08 0.08 0.08 0.08 0.08 0.07 0.07 0.08

Upsets

Mishaps (Dig-ins) 1.07 1.15 1.19 1.19 1.24 1.19 1.18 1.07 1.15 1.19

Total 46 45 45 43 43 42 41 40 41 42

1 Emissions are not actually 0, but too small to show at this level of precision.

Note: Totals may not sum due to independent rounding.



### A-157