### A

- 1 

# Annexes to the Inventory of U.S. GHG Emissions and Sinks

The following seven annexes provide additional information related to the material presented in the main body of

this report as directed in the UNFCCC Guidelines on Reporting and Review (GE.03

- 60887). Annex 1 contains an analysis

of the key categories of emissions discussed in this report and a review of the methodology used to identify those key

categories. Annex 2 describes the methodologies used to estimate CO 2 

### emissions from fossil fuel combustion, the carbon

content of fossil fuels, and the amount of carbon stored in products from non

- energy uses of fossil fuels. Annex 3

discusses the methodologies used for a number of individual source categories in greater detail than was presented in the

main body of the report and includes explicit activity data and emission factor tables. Annex 4 presents the IPCC

reference approach for estimating CO 2 

### emissions from fossil fuel combustion. Annex 5 addresses the criteria for the

inclusion of an emission source category and discusses some of the sources that are excluded from U.S. estimates. Annex

6 provides a range of additional information that is relevant t o the contents of this report. Annex 7 provides data on the

uncertainty of the emission est imates included in this report. Finally, Annex 8 provides informa tion on the QA/QC

methods and procedures used in the development of the Inventory.

ANNEX 1 Key Category Analysis

................................ ................................ ................................ ................................ ................................ 2

ANNEX 2 Methodology and Data for Estimating CO 2 

### Emissions from Fossil Fuel Combustion

................................ ............................... 27

2.1. Methodology for Estimating Emissions of CO 2 

### from Fossil Fuel Combustion

................................ ................................ ..... 27

2.2. Methodology for Estimating the Carbon Content of Fossil Fuels

................................ ................................ ......................... 59

2.3. Methodo logy for Estimating Carbon Emitted from Non

- Energy Uses of Fossil Fuels

................................ ......................... 98

ANNEX 3 Methodological Descriptions for Additional Source or Sink Categories

................................ ................................ ................... 125

3.1. Methodology for Estimating Emissions of CH 4 

### , N 2 

### O, and Indirect Greenhouse Gases from Stationary Combustion

....... 125

3.2. Methodology for Estimating Emissions of CH 4 

### , N 2 

### O, and Indirect Greenhouse Gases from Mobile Combustion and

Me thodology for and Supplemental Information on Transportation

- Related GHG Emissions

................................ ................................ . 132

3.3. Methodology for Estimating Emissions from Commercial Aircraft Jet Fuel Consumption

................................ ................. 164

3.4. Methodology for Estimating CH 4 

### Emissions from Coal Mining

................................ ................................ .......................... 168

3.5. Methodology for Estimating CH 4 

### and CO 2 

### Emissions from Natural Gas Systems

................................ ............................. 175

3.6. Methodology for Estimating CH 4 

### and CO 2 

### Emissions from Petroleum Systems

................................ ............................... 202

3.7. Methodology for Estimating CO 2, 

### N 2 

### O and CH 4 

### Emissions from the Incineration of Waste

................................ .............. 209

3.8. Methodology for Estimating Emissions from International Bunker Fuels used by the U.S. Military

................................ .. 214

3.9. Methodology for Estimating HFC and PFC Emissions from Substitution of Ozone Depleting Substances

...................... 219

3.10. Methodology for Estimating CH 4 

### Emissions from Enteric Fermentation

................................ ................................ ............ 240

3.11. Methodology for Estimating CH 4 

### and N 2 

### O Emissions from Manure Management

................................ ............................ 258

3.12. Methodology for Estimating N 2 

### O Emissions and Soil Organic C Stock Changes from Agricultural Soil Management

(Cropland and Grassland)

................................ ................................ ................................ ................................ ................................ ........ 287

3.13. Methodology for Estimating Net Carbon Stock Changes in Forest Lands Remaining Forest Lands

................................ 338

3.14. Methodology for Estimating CH 4 

### Emissions from Landfills

................................ ................................ ................................ 367

ANNEX 4 IPCC Reference Approach for Estimating CO 2 

### Emissions from Fossil Fuel Combustion

................................ ....................... 385

AN NEX 5 Assessment of the Sources and Sinks of Greenhouse Gas Emissions Not Included

................................ ............................. 395

ANNEX 6 Additional Information

................................ ................................ ................................ ................................ .............................. 397

6.1. Global Warming Potential Values

................................ ................................ ................................ ................................ ...... 397

6.2. Ozone Depleting Substance Emissions

................................ ................................ ................................ ............................. 406

6.3. Sulfur Dioxide Emissions

................................ ................................ ................................ ................................ ................... 407

6.4. Complete List of Source Categories

................................ ................................ ................................ ................................ .. 409

6.5. Constants, Units, and Conversions

................................ ................................ ................................ ................................ ... 410

6.6. Abbreviations

................................ ................................ ................................ ................................ ................................ ..... 412

6.7. Chemical Formulas

................................ ................................ ................................ ................................ ............................ 417

ANNEX 7 Uncertainty

................................ ................................ ................................ ................................ ................................ ............... 421

7.1. Overview

................................ ................................ ................................ ................................ ................................ ............ 421

7.2. Methodology and Results

................................ ................................ ................................ ................................ .................. 421

7.3. Planned Improvements

................................ ................................ ................................ ................................ ...................... 428

7.4. Additional Information on Uncertainty Analyses by Source

................................ ................................ ............................... 429

ANNEX 8 QA/QC Procedures

................................ ................................ ................................ ................................ ................................ .. 450

8.1. Background

................................ ................................ ................................ ................................ ................................ ........ 450

8.2. Purpose

................................ ................................ ................................ ................................ ................................ .............. 450

8.3. Assessment Factors

................................ ................................ ................................ ................................ .......................... 451

### A

- 2 Inventory of U.S. Greenhouse Ga s Emissions and Sinks: 1990

- 2012 

# ANNEX 1 Key Category Analysis

The United States has identified national key categories based on the estimates presented in this report. The

IPCC’s Good Practice Guidance (IPCC 2000) describes a key category as a “[category] that is prioritized within th e national inventory system because its estimate has a significant influence on a country’s total inventory of direct

greenhouse gases in terms of the absolute level of emissions, the trend in emissions, or both.” By definition, key categories

are sources or sinks that have the greatest contribution to the absolute overall level of national emissions in any of the

years covered by the time series. In addition, when an entire time series of emission estimates is prepared, a determination

of key categories m ust also account for the influence of the trends of individual categories. Therefore, a trend assessment

is conducted to identify source and sink categories for which significant uncertainty in the estimate would have

considerable effects on overall emiss ion trends. Finally, a qualitative evaluation of key categories should be performed, in

order to capture any key categories that were not identified in either of the quantitative analyses, but can be considered ke y

because of the unique country

- specific e stimation methods.

The methodology for conducting a key category analysis, as defined by IPCC’s Good Practice Guidance (IPCC

2000), IPCC’s Good Practice Guidance for Land Use, Land

- Use Change, and Forestry (IPCC 2003) , and IPCC’s 2006

Guidelines for Nation al Greenhouse Gas Inventories IPCC (2006) ; includes:

 Tier 1 approach (including both level and trend assessments);

 Tier 2 approach (including both level and trend assessments, and incorporating uncertainty analysis); and

 Qualitative approach.

This Annex presents an analysis of key categories, both for sources only and also for sources and sinks (i.e.,

including LULUCF); discusses Tier 1, Tier 2, and qualitative approaches to identifying key categories; provides level and

trend assessment equations; and pr ovides a brief statistical evaluation of IPCC’s quantitative methodologies for defining

key categories. Table A

- 1 presents the key categories for the United States (including and excluding LULUCF categories)

using emissions and uncertainty data in this report, and ranked according to their sector and global warming potential

weighted emissions in 2012. The table also indicates the criteria used in ide ntifying these categories (i.e., level, trend, Tier

1, Tier 2, and/or qualitative assessments).

### A

- 186 Inventory of U.S. Greenhouse Ga s Emissions and Sinks: 1990

- 2012

Table A

- 129 : 2012 Data and CH 4 

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

2012 EPA Inventory Values

Activity Activity Data Emission Factor (Potential) aa Calculated

Potential

Emissions

(Mg)

Fugitives

Pipeline Leaks 303,126 

### miles a,1 1.55 Scfd/ mile b 3,311.4

Compressor Stations (Transmission)

Station 1,799 

### stations c,2 8,778 Scfd/station b 111,037.1

Reciprocating Compressor 7,235 

### compressors c,2 15,205 Scfd/ compressor b 773,294.3

Centrifugal Compressor (wet seals) 659 

### compressors d,2 50,222 Scfd/ compressor d 232,825.7

Centrifugal Compressor (dry seals) 66 

### compressors d,2 32,208 Scfd/ compressor d 14,971.9

Compressor Stations (Storage)

Station 344 

### stations e,2 21,507 Scfd/ station b 52,013.2

Reciprocating Compressor 1,012 

### compressors e,2 21,116 Scfd/ compressor b 150,224.7

Centrifugal Compressor (wet seals) 70 

### compressors d,2 45,441 Scfd/ compressor d 22,346.7

Centrifugal Compressor (dry seals) 29 

### compressors d,2 31,989 Scfd/ compressor d 6,531.7

Wells (Storage) 16,042 

### wells b,2 115 Scfd/well b 12,912.2

M&R (Trans. Co. Interconnect) 2,698 

### stations c,2 3,984 scfd/station b 75,573.6

M& R (Farm Taps + Direct Sales) 80,009 

### stations c,2 31 scfd/station b 17,548.7

Vented and Combusted

Dehydrator vents (Transmission) 1,146,991 

### MMscf/year b,2 93.72 

### scf/MMscf b 2,070.4

Dehydrator vents (Storage) 1,782,492 

### MMscf/year b,2 117 

### scf/MMscf b 4,022.9

Compressor Exhaust

Engines (Transmission) 50,908 

### MMHPhr b,2 0.24 

### scf/HPhr b 235,315.3

Turbines (Transmission) 12,147 

### MMHPhr b,2 0.01 

### scf/HPhr b 1,333.5

Engines (Storage) 4,387 

### MMHPhr b,2 0.24 

### scf/HPhr b 20,277.1

Turbines (Storage) 1,541 

### MMHPhr b,2 0.01 

### scf/HPhr b 169.2

Generators (Engines) 2,491 

### MMHPhr b,2 0.24 

### scf/HPhr b 11,515.2

Generators (Turbines) 29 

### MMHPhr b,2 0.01 

### scf/HPhr b 3.2

Pneumatic Devices Transmission +

Storage

Pneumatic Devices Transmission 70,827 

### devices f,2 162,197 

### Scfy/device b 221,256.9

Pneumatic Devices Storage 13,542 

### devices e,2 162,197 

### Scfy/device b 42,304.0

Routine Maintenance/Upsets

Pipeline venting 303,126 

### miles a,1 31.65 

### Mscfy/mile b 184,779.2

Station Venting Transmission + Storage

Station Venting Transmission 1,799 compressor

stations c,2 4,359 

### Mscfy/station b 151,065.9

Station Venting Storage 344 compressor

stations e,2 4,359 

### Mscfy/station b 28,882.0

LNG Storage

-

LNG Stations 70 

### stations f,g,3 21,507 

### scfd/station b 10,622.8

LNG Reciprocating Compressors 270 

### compressors

f,g,3 21,116 

### scfd/comp b 40,146.5

LNG Centrifugal Compressors 64 

### compressors

f,g,3 30,573 

### scfd/comp b 13,766.0

LNG Compressor Exhaust

LNG Engines 579 

### MMHPhr f,g,3 0.24 

### scf/HPhr b 2,677.7

LNG Turbines 113 

### MMHPhr f,g,3 0.01 

### scf/HPhr b 12.4

LNG Station Venting 70 

### stations f,g,3 4,359 

### Mscfy/station b 5,898.6

LNG Import Terminals

LNG Stations 8 

### stations f,g,3 21,507 

### scfd/station b 1,164.2

LNG Reciprocating Compressors 37 compressors f,g,3 21,116 

### scfd/compressor b 5,551.8

LNG Centrifugal Compressors 7 compressors f,g,3 30,573 

### scfd/compressor b 1,418.5

LNG Compressor Exhaust

LNG Engines 774 

### MMHPhr f,g,3 0.24 

### scf/HPhr b 3,576.6

LNG Turbines 178 

### MMHPhr f,g,3 0.01 

### scf/HPhr b 19.5

LNG Station Venting 8 

### stations f,g,3 4,359 

### Mscfy/station b 646.4

Regulatory Reductions (Gg) 

### (0.0)

Voluntary Reductions (Gg) 

### (390.1)

### A

- 187

Total Reductions (Gg) 

### ( 390.1 )

Total Potential Emissions (Gg) 

### 2,46 1.1

Total Net Emissions (Gg) 

### 2, 071.0

a Pipeline and Hazardous Materials Safety Administration (PHMSA), Offic e of Pipeline Safety (OPS) (2013 )

b EPA/GRI (1996), Methane Emissions from the Natural Gas Industry

c ICF (2008), Natural Gas Model Activity Factor Basis Change

d ICF (2010), Emissions from Centrifugal Compressors

e ICF (1997), Additional Changes to Activity Factors for Portions of the Gas Industry

f ICF (1996), Estimation of Activity Factors for the Natu ral Gas Exploration and Production Industry in the U.S.

g EIA (2004), US LNG Markets and Uses

1 Activity data for 2012 available from source.

2 Ratios relating other factors for which activity data are available.

3 2011 activity data are used to determine some or all of the 2012 activity (to be updated).

aa Emission factors listed in this table are for potential emissions (unless otherwise indicated in a footnote). For many of the se sources, emission

reductions are subtracted from potential emissions to calculate net emissions. For this reason, emission factors presented in these tables

cannot be used to directly estimate net emissions from these sources. See detailed explanation of methodology above.