# April 16, 2007 

# TECHNICAL REPORT

Fugitive Emissions Pilot Project:

Measurement of Natural Gas Emissions from the

Canadian Natural Gas Transmission and Distribution Industry

PREPARED FOR:

Canadian Energy Partnership for Environmental Innovation (CEPEI)

75 Winbledon Road Guelph, Ontario

N1H 7V7

PREPARED BY:

Clearstone Engineering Limited 700, 900-6 Avenue S.W. Calgary, Alberta T2P 3K2

# i 

# Executive Summary

A fugitive emission measurement program was conducted from 2004 to 2006 at a representative selection of natural gas transmission, storage and distribution facilities from across Canada. This was done as part of a fugitive emissions pilot project sponsored by CRESTech and included the development of a formal leak detection and measurement protocol aimed at providing reliable and consistent results. The objectives of this work were to improve the quality, coverage and compatibility of emission factors and average unit-specific component counts used to estimate fugitive methane emissions from the Canadian natural gas transmission, storage and distribution industry, and to calculate the uncertainty bounds associ ated with these industry-specific emission

factors.

The selected natural gas facilities were chosen, in consultation with the project sponsors, to provide increased data for the source categories estimated to contribute most to total uncertainty in the gas industry’s national GHG emissions inventory, while covering the range of operators, geographic locations, age, and type of facility or installation. Leak detection and measurement surveys were conducted at 149 facilities across the country including 121 distribution facilities (i.e., 50 regulator/gate stations, 20 commercial meter sets, 18 farm taps, 30 residential meter sets and 3 industrial meter sets), 27 gas transmission facilities (i.e., 2 mainline block valves, 13 receipt/sales meter stations and 12 compressor stations) and 1 liquefied natural gas (LNG) storage facility. The results were combined with the data from a similar measurement program conducted in 1995/96 [1], as well as the results of several leak measurement programs sponsored by individual gas companies (i.e., Alliance Pipeline and Terasen). The combined data set represents emission survey results from 438 facilities located throughout British Columbia, Alberta, Saskatchewan, Manitoba, Ontario and Quebec and operated by the following study participants: Alta Gas, Atco Gas, Atco Pipelines, Duke Energy, Enbridge, Gaz Metro, Manitoba Hydro, TransCanada Pipelines and Union Gas. The leak measurement work was performed by Clearstone Engineering in all of these cases, with the exception of the 1995/96 study, which was performed jointly with

Environment Canada.

Before combing the results, some checks were performed to confirm that the data were all from the same population (i.e., that no st atistically significant changes have occurred since the 1995/96 study). The combined results show that the leak-rate distribution for most component categories is highly skewed rather than normally distributed. As a result, much greater sample sizes are needed to accurately characterize the leak rate

distribution than would be the case if the distributions were normal.

While in most cases the new average em ission factors have changed little from the current factors being used by the Canadian natural gas industry, in a few cases quite significant changes have occurred and the uncertainty limits on these factors have actually increased. In these cases, the developed emissions factors have been affected by a few particularly large leakers detected during the current study at different facilities. It could be argued that these data are outliers and should be excluded from the emission factor calculations. However, it has viewed that these extreme leaker results actually help to better delineate the full profile of the skewed distributions for the respective component categories. Accordingly, these extreme values were retained as valid points

in the emissions distribution.

# ii The uncertainties in the developed emission factors were determined based on a 95- percent confidence interval in accordance with the IPCC (2000) Good Practice Guidance. This differs from the current practice in the United States where the US Environmental Protection Agency has been using a 90-percent confidence interval in GHG-related uncertainty analyses.

Overall, the data collected during the 2005/06 field measurement campaign at a large selection of transmission, storage and distribution facilities has re-affirmed and highlighted a number of key findings from previo us studies of fugitive emissions in the industry. No new trends or anomalies were detected in the compiled data.

There were two LNG storage facilities included in the combined data set. Both facilities were relatively new but were operated by different companies and located in different provinces. Very little equipment at either facility was actually in LNG service, beyond a few fittings on the LNG spheres and vaporizers. Most of the equipment was in natural gas service and associated with the compressor units. There was insufficient data available to draw any meaningful conclusions regarding possible difference in fugitive emissions at LNG facilities; however, there was not indication of any differences.

The component counts used to develop the emission factors were all prepared by Clearstone Engineering based on actual counts performed while at the facilities. In some cases operators also provided their own counts which were understood to have largely been derived from drawings rather than field counts. The results for smaller facilities such as distribution meter stations tended to agree well with the field counts; however, the company supplied counts for larger facilities often greatly understated the population of components determined from the field counts (i.e., by as much as an order of magnitude). This reflects the lack of detail s hown on most types of drawings, particularly for third party packages such as compressors. As well, it highlights the need to improve the quality of component counts being compiled by some operators..

# iii 

# Table of Contents

Executive Summary ........................................................................................................... i List of Figures................................................................................................................

... iv

List of Tables.................................................................................................................

... vi

1.0 Introduction............................................................................................................ 1

2.0 Field Measurement Program................................................................................. 2

2.1 Surveyed Facilities ............................................................................................ 2

2.2 Component Screening....................................................................................... 4

2.3 Leak Rate Measurement ................................................................................... 4

2.4 Component Counts ........................................................................................... 4

3.0 Results .................................................................................................................. 5

3.1 Average Emission Factors ................................................................................ 5

3.2 Default Component Counts ............................................................................. 10

4.0 Conclusions......................................................................................................... 13

References.....................................................................................................................

. 14 Glossary.......................................................................................................................

... 15 Appendix A: Average Emission Factors by Component Type ..................................... 19 Appendix B: Comparison of Average Emission Factors from Published Sources to Current Study by Component Type................................................................................. 26 Appendix C: Leaker Data Distribution.......................................................................... 29 Appendix D: Cumulative Leak Contributions................................................................ 40 Appendix E: Default Component Counts and Confidence Intervals ............................ 46 Appendix F: Changes observed from 1995/1996 to 2005/2006 data sets................... 51 Appendix G: Measured Emissions from 2005/2006 Field Campaign....................... 56

# iv 

# List of Figures

Figure A-1 Average Emission Factors – Centrifugal Compressor Seals ....................... 20

Figure A-2 Average Emission Factors – Reciprocating Compressor Seals................... 20

Figure A-3 Average Emission Factors – Connector....................................................... 21

Figure A-4 Average Emission Factors – Control Valve.................................................. 21

Figure A-5 Average Emission Factors – Controller........................................................ 22

Figure A-6 Average Emission Factors – Blowdown....................................................... 22

Figure A-7 Average Emission Factors – Open-Ended Line ........................................... 23

Figure A-8 Average Emission Factors – Orifice Meter................................................... 23

Figure A-9 Average Emission Factors – Other Flow Meter............................................ 24

Figure A-10 Average Emission Factors – Pressure Regulator ........................................ 24

Figure A-11 Average Emission Factors – Pressure Relief Valve..................................... 25

Figure A-12 Average Emission Factors – Valve .............................................................. 25

Figure B-1 Comparison of Average Emission Factors – All Equipment Components ... 26

Figure B-2 Comparison of Average Emission Factors – Pressure Regulator, Connector

and Other Flow Meter................................................................................... 27

Figure B-3 Comparison of Average Emission Factors – Orifice Meter, Control Valve and

Valve ............................................................................................................ 27

Figure B-4 Comparison of Average Emission Factors – Open-Ended Line, Controller

and Pressure Relief Valve............................................................................ 28

Figure B-5 Comparison of Average Emission Factors – Blowdown, Centrifugal Compressor Seal and Reciprocating Compressor Seal............................... 28

Figure C-1 Transmission Leaker Data Distribution – Centrifugal Compressor Seals .... 30

Figure C-2 Transmission Leaker Data Distribution – Reciprocating Compressor Seals 30

Figure C-3 Transmission Leaker Data Distribution – Connector.................................... 31

Figure C-4 Transmission Leaker Data Distribution – Control Valve............................... 31

Figure C-5 Transmission Leaker Data Distribution – Controller..................................... 32

Figure C-6 Transmission Leaker Data Distribution – Blowdown.................................... 32

# v Figure C-7 Transmission Leaker Data Distribution – Open-Ended Line ........................ 33

Figure C-8 Transmission Leaker Data Distribution – Orifice Meter................................ 33

Figure C-9 Transmission Leaker Data Distribution – Pressure Regulator ..................... 34

Figure C-10 Transmission Leaker Data Distribution – Pressure Relief Valve ............. 34

Figure C-11 Transmission Leaker Data Distribution – Valve....................................... 35

Figure C-12 Distribution Leaker Data Distribution – Centrifugal Compressor Seals ... 35

Figure C-13 Distribution Leaker Data Distribution – Connector .................................. 36

Figure C-14 Leaker Data Distribution – Control Valve ................................................ 36

Figure C-15 Distribution Leaker Data Distribution – Blowdown................................... 37

Figure C-16 Distribution Leaker Data Distribution – Open-Ended Line....................... 37

Figure C-17 Distribution Leaker Data Distribution – Pressure Relief Valve ................ 38

Figure C-18 Distribution Leaker Data Distribution – Pressure Regulator .................... 38

Figure C-19 Distribution Leaker Data Distribution – Valve .......................................... 39

Figure D-1 Cumulative Leak Contributions for Transmission Facilities – All equipment
components.................................................................................................. 40

Figure D-2 Cumulative Leak Contributions – Transmission – Centrifugal Compressor

Seals ............................................................................................................ 41

Figure D-3 Cumulative Leak Contributions – Transmission – Reciprocating Compressor

Seals ............................................................................................................ 41

Figure D-4 Cumulative Leak Contributions – Transmission – Connector ...................... 42

Figure D-5 Cumulative Leak Contributions – Transmission – Controller Vent............... 42

Figure D-6 Cumulative Leak Contributions – Transmission – Control Valve ................. 43

Figure D-7 Cumulative Leak Contributions – Transmission – Blowdown....................... 43

Figure D-8 Cumulative Leak Contributions – Transmission – Open-Ended Line........... 44

Figure D-9 Cumulative Leak Contributions – Transmission – Orifice Meter .................. 44

Figure D-10 Cumulative Leak Contributions – Transmission – Pressure Relief Valve 45

Figure D-11 Cumulative Leak Contributions – Transmission – Valve ......................... 45

# vi 

# List of Tables

Table 2-1 Scope of Survey............................................................................................. 3

Table 3-1 Average Emission Factors for Gas Transmission and Distribution Facilities

from the Combined Data Set.......................................................................... 7

Table 3-2 Comparison of Average Emission Facto rs (kg/h/source) from Published Sources to the 1995/1996 GTC/EC Study and the Combined Data Set........ 9

Table 3-3 Equipment Schedules for Gas Transmission Facilities. ............................... 11

Table 3-4 Equipment Schedules for Gas Distribution Facilities.................................... 12

Table E-1 Confidence Limits on Equipment Schedules for Gas Transmission Facilities Based on 2005/2006 Measurement Campaign and Independent Company

Studies Data Set. ......................................................................................... 46

Table E-2 Confidence Limits on Equipment Schedules for Gas Distribution Facilities and Meter/Regulation Stations Based on 2005/2006 Measurement Campaign and Independent Company Studies Data Set............................. 48

Table E-3 Confidence Limits on Equipment Schedules for Gas Distribution Commercial and Residential Meter Sites Based on 2005/2006 Measurement Campaign

Data Set. ...................................................................................................... 50

Table F-1 Comparison of Average Emission Factors for Gas Transmission Facilities. 51

Table F-2 Changes from 1995/1996 to 2005/2006 Gas Transmission Data Sets........ 52

Table F-3 Comparison of Average Emission Factors for Gas Distribution Facilities and Meter/Regulation Stations............................................................................ 53

Table F-4 Changes from 1995/1996 to 2005/2006 Gas Distribution Data Sets ........... 54

Table F-5 Comparison of Average Emission Factors for Commercial and Residential

Gas Distribution Sites................................................................................... 55

Table F-6 Changes from 1995/1996 to 2005/2006 Commercial and Residential Gas

Distribution Data Sets................................................................................... 55

Table G-1 2005/2006 Measured Emissions by Facility Type........................................ 56

Table G-2 Top Twenty Leakers from 2005/2006 Emissions Survey............................. 56

# 1 

# 1.0 Introduction

The pilot measurement program comprised tw o parts. The first part was to develop a standard leak measurement protocol for detec ting, measuring and classifying leaks at natural gas facilities. The second part, which is the focus of this document, was to apply the protocol at a representative sampling of natural gas transmission and distribution facilities to increase the current database of leak data for the industry and then use this information to develop improved emission factors and default unit-specific component

counts.

Leak detection and measurement data collected during the 2005/2006 field campaign at 149 study participant facilities were combined with data collected during recent testing programs undertaken by independent companies 1 

# and with the data gathered for the1995/1996 GTC/EC study of Western Canadian natural gas facilities [1]. The combined data set was used to develop emission factors for estimating fugitive natural gas losses at Canadian gas transmission, storage and distribution facilities.

A summary of the leak detection and quantification program is given in Section 2. Section 3 provides a summary of the re sults including the updated average emission, comparison of the developed factors to published data and average unit-specific component counts. The conclusions of the study are presented in Section 4. A graphical comparison of the emission factors, by co mponent type, developed by the current study to those and developed by the 1995/1996 GTC/EC Study of Western Canadian natural gas facilities is given in Appendix A, along with the associated uncertainty bounds for each of the factors. Appendix B provides a graphical comparison of the average emissions to published factors. An examination of leaker data distribution profiles and

cumulative leak contributions are avail able in Appendix C and Appendix D, respectively. Appendix E presents the confidence limits for the developed average unit-specific component counts. The changes in leak fr equency and emission factors between the 1995/1996 and 2005/2006 data sets are examined in Appendix F. Finally, Appendix G provides a summary of the total losse s measured during the 2005/2006 field campaign and a listing of the top leaks encountered.

1 

# Data used with permission.

# 2 

# 2.0 Field Measurement Program

The field measurement program was conducted from 2005 to 2006 at a selection of facilities which provided a uniform representation of the Canadian natural gas transmission, storage and distribution industry. This work comprised identifying all natural gas equipment leaks at each host faci lity, measuring the amount of emissions from each detected leak, developing equipment counts and estimating the amount of emissions from non-leaking sources. The work was completed in accordance with the Fugitive Emissions Measurement Protocol [2]. A component was considered to be leaking if it produced a screening value of 10,000 ppm or greater using a portable organic vapour analyzer when screened in accordance with US Environmental Protection Agency’s Method 21.



# 2.1 Surveyed Facilities

Facilities included in the study were selected by the industry participants and the project steering committee with the intent of providing a uniform representation of the Canadian natural gas transmission, storage and distribution system. Consideration was given to age, type, location and operator when selecting facilities.

Measurement data collected during the study were combined with other similar leak data that were available and satisfied the basic requirements of the developed Leak Measurement Protocol. These additional data included the results of an industry sponsored leak measurement program conducted in Canada in 1995/96 [1] and several recent leak measurement campaigns sponsored by individual gas companies in Canada (namely, Alliance Pipeline and Terasen). Table 2-1 provides a summary of the compiled data sources along with the number and types of facilities that were surveyed in each of these cases. The combined data set represents survey results from 44 compressor stations, 33 sales and receipt meter stations, 47 block/control valve stations, which includes 6 border meter stations, 2 LNG storage facilities, 26 industrial meter sites, 56 commercial meter sites, 111 residential meter sites, 28 farm taps and 94 regulation/gate stations. These facilities are located throughout British Columbia, Alberta, Saskatchewan, Manitoba, Ontario and Quebec and are operated by the following study participants: Alta Gas, Atco Gas, Atco Pipelines, Duke Energy, Enbridge, Gaz Metro, Manitoba Hydro, TransCanada Pipelines and Union Gas.3Table 2-1 Scope of SurveyGAS DISTRIBUTIONGAS TRANSMISSIONTOTALRegulator /GateStationCommercialMeter SetFarmTapResidentialMeter SetIndustrialMeter SetBlock /ControlValveStation1Receipt/ SalesMeterStation1CompressorStation1StorageFacility1Block /ControlValveStationReceipt/ SalesMeterStationCompressorStationStorageFacility2005/2006FacilitiesSurveyed149 50 20 18 30 3 0 0 0 0 2 13 12 1OtherSurveyedFacilities2106 12 15 0 14 5 22 8 8 1 12 0 9 0TOTALCURRENTSTUDY2556235184482288114132111995/1996GTC/ECStudy183 32 21 10 67 18 0 0 0 0 11 12 12 0COMBINEDDATA SET438945628111262288125253311Odourized transmission facilities are deemed to be in distribution service and are categorized as such for the purpose of developing average emission factors2Not all equipment surveyed at some facilities

# 4 

# 2.2 Component Screening

Equipment components in pressurized natural gas service were screened for leaks in accordance with the methodology presented by the U.S. EPA [3] and following the methodology outlined in the Fugitive Emissions Measurement Protocol [2]. The types of components surveyed included connectors, va lves, pressure relief devices, open-ended lines, blowdown vents (during passive periods ), regulator and actuator diaphragms, flow meters, and compressor seal vents.

Screening was conducted using ultrasonic leak detectors, bubble tests with soapsolution and portable hydrocarbon vapour analyzers calibrated to methane (BascomTurner Gas Sentry CGI-201 and CGI-211). A screening value of 10,000 ppmv in the vicinity of the component was used at the leak definition. Component determined to be emitting based on qualitative screening techniques were also screened using quantitative screening techniques to verify the leak definition was exceeded. Identified leaking equipment components were marked with sequentially numbered tags indicating the source of the leakage.



# 2.3 Leak Rate Measurement

Emission rates were measured for all components determined to be leaking. The

HiFlow TM 

# Sampler was the primary instrument used to quantify emissions from leaking sources. However, flow through meters (i.e. rotary meter, diaphragm meter and rotameter) and velocity probes (i.e. hot wire anemometer, thermal dispersion anemometer, vane anemometer, and micro-tip vane anemometer) were also utilized when the source type and emission rate was appropriate. Section 4 of the Fugitive Emissions Measurement Protocol [2] outlines the leak measurement techniques applied. Data collection and reporting was done in accordance with the source classification scheme provided in Section 2 of the Protocol.



# 2.4 Component Counts

Detailed counts of the components in natural gas service for each facility surveyed were developed by Clearstone Engineering in accordance with the Fugitive Emissions Measurement Protocol. Independent component counts were provided by approximately half the operators. Count verification results showed significant differences between the two data sets for some facility types and highlighted some of the challenges related to obtaining an accurate component population:

• Relying on piping and instrumentation drawings to develop equipment component counts can lead to a significant underestimation of the component population. P&IDs typically lack sufficient detail to develop an accurate count, details on packaged units are generally missing (particularly, for fuel gas system piping), and open-ended lines are not shown on drawings.

• A systematic approach, such as that laid out in the Protocol, must be employed to avoid either missing equipment components or double counting.

# 5 • Process knowledge and training is needed to recognize and exclude non-target service applications such as electrical conduit, coolant, heat medium and lubricating oil.

• Facilities of the same type and size may have very different numbers of components due to differences in design practices and the number of trains
present.

Ultimately, only the Clearstone component counts were used to develop the average emission factors presented in the following section. Refer to Section 2.3 of the Fugitive

Emission Measurement Protocol for a discu ssion of the component counting guidelines and basic component categories.



# 3.0 Results

Natural gas companies typically use aver age emission factors and estimated component populations to determine the amount of methane emitted at their facilities due to fugitive equipment leaks. This is done using the following relation:



# ∑∑

⋅ ⋅ =

i j
j i j i 

# X N EF ER

, 

# (1)

Where: ER is the total emission rate for the target source population EF is the average emission factor N is the number of sources (src) X is the mass fraction of the target pollutant in the process fluid

Updated average emission factors developed from the expanded leak measurement data set are presented in Section 3.1 below. Updated default unit-specific component counts are presented in Section 3.2; however, these values are derived from the 2005/2006 and independent study measurement data only since the 1995/96 GTC/EC data set does not contain the detail required to evaluate the confidence limits on the
component counts.

Prior to combining the data sets, various statistical tests and quality assurance checks were performed on the data to ensure that they are representative of the same populations, to identify and deal with outliers and to harmonize component codes and database structures. Several comparisons were made between data from the current study (i.e., the 2005/2006 field campaign and recent independent company studies) and that from the 1995/1996 study. This included comparing the 95 percent confidence limits on the data sets, the data distributions and component populations.



# 3.1 Average Emission Factors

The average emission factors developed based on a statistical analysis of the total combined data set of leak measurement and component counts are presented in Table 3-1 along with their 95 percent confidence limits. The previous study [1] of the Canadian natural gas transmission, storage and distribution industry concluded that fugitive equipment leaks are dependent on the industry sub-sector and component type. Consequently, emission factors developed in th is study are classified accordingly. Following the Fugitive Emissions Measurement Protocol, odourized transmission

# 6 facilities are deemed to be in distribution service as fugitive emissions from odourized transmission facilities are lower than their unodourized counterparts. Previous study has shown that components in gas transmission se rvice tend to leak more, on average, than components in gas distribution service and that odourization of the distribution gas is likely an important factor [2].

The average emission factors represent the total amount of organic emission observed in each source category divided by the corresponding number of potential sources. Consequently, the factors account for emissions from both leaking and non-leaking sources. Emission rates for all leaking components were quantified using the methods described in the Fugitive Emission Measurement Protocol. Emissions from non-leaking equipment component were assigned the average non-leaking emission rates presented in the US EPA Protocol for Equipment Leak Emission Estimates [7].

The 95 percent confidence limits provide an indication of the variability of the compiled average emission factors. In general, the confidence interval is narrow when there were a large number of data points or the data were clustered around the mean. If the data showed a wide variability around the mean or there were few data points, the 95 percent confidence interval is wide. Comparing the c onfidence limits of two data sets provides a simple means of establishing if the data sets are from the same population.

A comparison of the updated average emissi on factors to those developed from the 1995/1996 study and to factors published for U.S. gas production [4], upstream oil and gas [5] and U.S. gas transmission systems [6] is presented in Table 3-2.

An examination of the updated average emission factors for the Canadian natural gas transmission, storage and distribution indus try shows that both the average emission factors and the 95 percent confidence limit s have increased for a number of source categories. These changes to the average emission factors are attributed to the highly skewed emission rate distributions for leaking components and the inclusion of a few particularly big leakers detected during the current measurement program. Although most equipment components are considered non-leaking, those that do satisfy the leak definition contribute almost all the emissions. Furthermore, within the subset of leaking equipment components, the majority of emissions result from only a few big leakers. The top few leakers in each category, therefore, have a significant impact on the average emission rate. As a result of the highly skewed emission rate distributions encountered, sample sizes must be quite large to see the full range of emission rates.

Additionally, the confidence limits for the 1995/96 data are believed to be artificially tight due to the use of published leak-rate correlations to estimate emissions for some of the leaks detected during that study (i.e., actual leak rate measurements were only performed on what appeared to be the greatest leakers at each site).

Please refer to Appendix A for a graphical comparison of the average emission factors developed from 1995/1996 data to those from the 2005/2006 data sets and the combined data set, and to Appendix F for tabular summaries. Appendix B provides a graphical comparison of average emission factor s to published sources. An examination of the leaker data distribution and cumulative leak contribution, both by component type, are provided in Appendix C and Appendix D, respectively.

# 7 Table 3-1 Average Emission Factors for Ga s Transmission and Di stribution Facilities

from the Combined Data Set.

Gas Transmission Facilities 1



# 95% Confidence Limits

Source Number of

Sources Leak Frequency Average

Emissions (kg TOC/h/source) Lower Upper

Compressor Seal – Centrifugal 2 

# 103 64.1 1.269E+00 8.197E-01 1.718E+00

Compressor Seal – Reciprocating 2 

# 167 40.1 1.073E+00 6.130E-01 1.533E+00

Connector 3 

# 145829 0.9 4.471E-04 1.957E-04 6.985E-04

Control Valve 4 

# 782 9.0 1.650E-02 1.082E-02 2.219E-02

Controller 5 

# 50 90.0 2.371E-01 9.941E-02 3.747E-01

Station or Pressurized Blowdown System 6 

# 219 59.8 3.405E+00 0.000E-00 7.885E+00

Open-Ended Line 928 58.1 9. 183E-02 5.395E-02 1.297E-01

Orifice Meter 7 

# 185 22.7 4.863E-02 0.000E-00 1.066E-01

Other Flow Meter 8 

# 443 1.8 9.942E-06 2.223E-07 1.966E-05 Pressure Regulator 816 7. 0 7.945E-03 0.000E-00 1.882E-02

Pressure Relief Valve 612 31. 2 1.620E-01 2.906E-02 2.950E-01

Valve 9 

# 17029 2.8 4.131E-03 2.748E-03 5.514E-03

Gas Distribution Facilities a nd Meter/Regulation Stations 1



# 95% Confidence Limits

Source Number of

Sources Leak Frequency Average Emissions (kg TOC/h/source) Lower Upper

Compressor Seal – Centrifugal 2 

# Use Transmission Factor

Compressor Seal – Reciprocating 2 

# Use Transmission Factor

Connector 3 

# 52051 0.9 8.227E-05 3.792E-05 1.266E-04

Control Valve 4 

# 605 13.7 1.949E-02 1.127E-02 2.771E-02

Controller 5 

# 25 84.0 3.997E-01 1.158E-01 6.836E-01

Station or Pressurized Blowdown System 6 

# 42 9.5 5.878E-03 0.000E-00 1.591E-02

Open-Ended Line 969 49.9 6. 077E-02 3.086E-02 9.068E-02

Orifice Meter 7 

# 142 17.6 3.011E-03 1.890E-03 4.131E-03

Other Flow Meter 8 

# 348 2.0 7.777E-06 0.000E-00 1.752E-05 Pressure Regulator 1323 2. 1 6.549E-04 0.000E-00 1.375E-03

Pressure Relief Valve 472 9. 5 3.944E-03 0.000E-00 8.865E-03

Valve 9 

# 9817 2.0 5.607E-04 1.892E-04 9.322E-04
TOC – Total organic compounds.

# 8 Gas Distribution Commercial and Residential Sites

95% Confidence Limits

Source Number of

Sources Leak Frequency Average

Emissions (kg TOC/h/source) Lower Upper

Connector 3 

# 8616 0.2 4.467E-06 8.226E-07 8.112E-06

Control Valve 4 

# 8 0.0 1.006E-02 0.000E-00 2.466E-02 Open-Ended Line 642 72.1 8. 355E-02 3.924E-02 1.279E-01

Orifice Meter 7 

# 107 19.6 3.274E-03 1.919E-03 4.630E-03

Other Flow Meter 8 

# 405 1.7 7.203E-06 0.000E-00 1.560E-05 Pressure Regulator 348 2.3 2 .329E-05 2.410E-07 4.633E-05

Pressure Relief Valve 78 3. 8 1.749E-03 0.000E-00 3.747E-03

Valve 9 

# 1340 0.1 2.173E-06 1.753E-06 2.593E-06
TOC – Total organic compounds.

1 

## Includes two LNG storage facilities. Odourized trans mission facilities are deemed to be in distribution

service and have been categorized as such for the purpose of developing average emission factors.

2 

## The Compressor Seal categories account for emission s from individual compressor seals (i.e., for a four

cylinder reciprocating compressor unit there are four seals so the compressor seal emissions for the unit would be four times the factor in the table).

3 

## Includes flanges, threaded connections and mechanical couplings.

4 

## Accounts for leakage from the stem packing and t he valve body. Emissions from the controller and

actuator are accounted for by the Instrument Controller and Open-Ended Line categories respectively. This factor applies to all valves with automatic actuators (i ncluding fuel gas injection valves on the drivers of reciprocating compressors).

5 

## The Instrument Controller category accounts for emi ssions from pneumatic control devices that use natural

gas as the supply medium.

6 

## Accounts for leakage past a valve seat through an open vent line to the atmosphere. These vents are

typically six inches or greater in diameter and are used to blowdown major process units or sections of pipeline. Small diameter open-ended lines such as t hose used to blowdown chart recorders, meter runs etc. are accounted for by the Open-Ended Line category.

7 

## Accounts for emissions from the orifice changer. Emissi ons from sources on pressure tap lines etc. are not

included in the factor (i.e., these em issions must be calculated separately).

8 

## Accounts for emissions from other types of gas flow meters (e.g., diaphragm, ultrasonic, roots, turbine and

vortex meters).

9 

## Accounts for emissions from the stem packing and t he valve body, and it applies to all types of block

valves (e.g., butterfly, ball, globe, gate, needle, or bit and plug valves). Leakage past the valve seat is accounted for by the Open-Ended Line emission categor y. Leakage from the end connections is accounted for by the connector category (i.e., one connector for each end).9Table 3-2 Comparison of Average Emission Factors (kg/h/source) from Published Sources to the 1995/1996 GTC/EC Study and the CombinedData Set.US Gas Production2SourceService(VOC)(TOC)UpstreamOil & GasOperations(TOC)3GRI GasTransmission(TOC)495/96 GTC/ECStudy GasTransmission(TOC)95/96GTC/ECStudy GasDistribution(TOC)95/96GTC/ECStudy GasDistribution- CR (TOC)CombinedData GasTransmission(TOC)1CombinedData GasDistribution(TOC)1CombinedData GasDistribution -CR (TOC)1Compressor Seal –CentrifugalG/V 0.042 0.20 0.80488 0.418 0.8139 - -1.269--Compressor Seal –ReciprocatingG/V 0.042 0.20 0.8 1.00 0.6616 - -1.073--Connector G/V 0.00046 0.0011 0.002530.000372 0.0002732 0.0001098 0.000006780.00044710.000082270.000004467Control Valve G/V 0.0075 0.2000.04351 0.0203 0.01969 0.01969 -0.016500.019490.01006Controller G/V - - 0.1996 0.411 0.4618 0.4618 -0.23710.3997-Blowdown G/V - - - 0.669 0.9369 0.9369 -3.4050.005878-Open-Ended Line G/V 0.014 0.022 0.001373 0.0284 0.08355 0.08355 0.083550.091830.060770.08355Orifice Meter G/V - - - - 0.003333 0.003333 -0.048630.0030110.003274Other Flow Meter G/V - - - - 0.00000906 0.00000906 0.000009060.0000099420.0000077770.000007203Pressure Regulator G/V - - - - 0.003304 0.001915 0.000021980.0079450.00065490.00002329Pressure Relief Valve G/V 0.014 0.19 0.12096 0.0157 0.2795 0.01665 0.00027170.16200.0039440.001749Valve G/V 0.0075 0.200 0.04351 0.00220 0.00214 0.001109 0.000003330.0041310.00056070.000002173G/V - Gas/Vapour- No data available or the source categorydoes not apply to this industry sector.1Not all equipment was surveyed at some facilities.2U.S. EPA. 1985. [3] Table 9.1.23Picard, D.J., B.D. Ross, and D.W.H.Koon. 1992. [5] Table 5, Page 49.4Adapted from; Hummel et al. 1996. [6] Table 4-15, page 51.

# 10 

# 3.2 Default Component Counts

To use the average emission factors presented in Table 3-1, the numbers of each of the different types of equipment components in each service category must be determined (see Section 2.4). In the absence of site-specific equipment component counts, however, the average equipment counts provided in Tables 3-2 and 3-3 may be used. These average counts were compiled by adding up the total number of each type of component at a particular type of facility and dividing by the number of such facilities surveyed. The industry-specific average component counts presented here are based on equipment component counts from 255 surveyed facilities, but data from the 1995/1996 GTC/EC study is not included.

Equipment schedules for residential meter sites, commercial meter sites, industrial meter sites, farm taps, district regulator stations and gate stations are presented on a per facility or per site basis. The amount of equipment at gas transmission facilities was found to vary widely from site to site. Refer to Appendix E where the upper and lower confidence limits on the component counts are provided. In an effort to manage the impact of this equipment variability, the schedules for meter stations are on a per meter run basis and compressor stations are on a per compressor unit basis. The amount of compressor yard station piping, excluding suction and discharge headers and valving for each unit, was found to be essentially independent of the number of compressor units [1]. Therefore, the total number of equipment components at a compressor station is determined by adding the components from yard piping to the components from each of the compressor units. If discharge coolers are used on site, the components from these

must also be added.11Table 3-3 Equipment Schedules for Gas Transmission Facilities.ComponentMainline BlockValveReceipt / SalesMeter Station2ReciprocatingCompressor Unit3CentrifugalCompressor Unit3CompressorStation YardPiping4CompressorDischarge Cooler5Facilities Surveyed113 168 25 29 21 9Compressor Seal –Centrifugal- - - 2 - -Compressor Seal –Reciprocating- - 4 - - -Connector 200 33 256 502 950 3527Control Valve 060 1 5 13 0Instrument Controller 0 0 0 0 1 -Blowdown 0 - 1 1 4 -Open-Ended Line 1 0 1 4 6 2Orifice Meter - 0 1 0 2 -Other Flow Meter 0 1 - 0 1 -Pressure Regulator 2 1 2 5 15 0Pressure Relief Valve 0 0 2 3 8 0Valve 36 7 22 120 217 331 Not all equipment at some facilities surveyed2 Number of components per meter run3 Number of components per compressor unit4 Number of components per compressor station. For a station with 2 reciprocating compressor units, the total number of connectors would be:2*256+985=14975 Number of components associated with discharge coolers at compressor stations. If the stationhas discharge coolers, add these additional components.6 A zero value indicates a fractional value less than 0.5.Please refer to AppendixE for further discussion.12Table 3-4 Equipment Schedules for Gas Distribution Facilities.Distribution – Commercialand ResidentialDistribution FacilitiesComponentResidentialMeter Set2CommercialMeter Set2FarmTap2IndustrialMeter Set2DistrictRegulatorStation2GateStation2BorderMeterStationMainlineBlockValveReciprocatingCompressorUnit3CentrifugalCompressorUnit3CompressorStation YardPiping4CompressorDischargeCooler5Facilities Surveyed144 35 18 15 32 30 6 22 2 12 9Compressor Seal –Centrifugal- - - - - - - - - 2 - -Compressor Seal –Reciprocating- - - - - - - - 5 - - -Connector 48 82 48 111 181 353 381 142 163 430 1172 527Control Valve 060 0 0 1 2 1 1 1 5 19 0Instrument Controller - - - - - 0 - 0 - - - -Blowdown - - - - - - - - 1 1 3 -Open-Ended Line - - - - 0 0 4 1 4 5 22 -Orifice Meter - 0 - 0 0 1 - 0 1 0 1 -Other Flow Meter 1 2 0 1 0 1 1 0 - 1 1 -Pressure Regulator 2 3 2 4 8 12 8 2 1 3 18 -Pressure Relief Valve 0 1 2 0 2 3 3 1 2 2 18 1Valve 8 14 13 26 40 64 62 33 20 83 222 141 Not all equipment at some facilities surveyed2 Number of components per meter set (forresidential, commercial and industrial meter sets) or site (for district and gate stations)3 Number of components per compressor unit4 Number of components per compressor station. For a station with 2 reciprocating compressor units, the total number of connectors would be:2*256+985=14975 Number of components associated with discharge coolers at compressor stations. If the stationhas discharge coolers, add these additional components.6 A zero value indicates a fractional value less than 0.5.Please refer to AppendixE for further discussion.

# 13 

# 4.0 Conclusions

Updated average emission factors and average unit-specific component counts for the Canadian natural gas transmission, storage and distribution industry have been developed using data collected during leak detection and measurement programs conducted since 1995 at natural gas facilities throughout Canada. The confidence limits associated with these results are also provided and may be used, in accordance with IPCC Good Practice Guidance (2000), to help develop quantitative uncertainty estimates

for emissions inventories.

An analysis of the data collected during the 2005/2006 field measurement campaign has re-affirmed and highlighted a number of key findi ngs from previous study of fugitive emissions in the industry:

• Components satisfying the leak definition (i.e., those with screening values greater than 10,000 ppm) account for the vast majority of fugitive emissions at all facility types. Although non-leak ing equipment components typically represent more than 98 percent of the component population, the contribution these components make to overall emissions is dwarfed by identified leakers.

• The distribution of emission rates for equipment components is highly skewed for most component categories, indicating that component population is predominantly composed of non-leaker s. The major exceptions are the compressor seal categories, which have relatively flat emission rate

distributions.

• Within the leaker subset of the component population, the distribution of emission rates is also highly skewed for all component categories. As a result, the top few leakers in each category have a significant impact on the average emission rate. Furthermore, a large sample population is required in order to define the shape of the emission rate distribution and see the full range of

leakers.

• Detailed, accurate component counts, ideally based on actual site surveys, are essential in developing emission inventorie s. The complexity of many facilities requires technicians both to be knowledgeable about the process and to follow a systematic approach such as that laid out in the Fugitive Emission Measurement

Protocol.

# 14 

# References

[1] Ross, B.D. and D.J. Picard. 1996. Measurement of Methane Emissions from Western Canadian Natural Gas Facilities – GTC Program #3 Environmental Technology Program.

[2] Clearstone Engineering Ltd. 2006. Canadian Energy Partnership for Environmental Innovation (CEPEI) – Fugiti ve Emissions Measurement Protocol.

[3] U.S. EPA (Environmental Protection Agency). 1997. Method 21 – Determination of Volatile Organic Compound Leaks. Available at: www.epa.gov/ttn/emc/promgate/m-21.pdf

.

[4] U.S. EPA. 1985. Compilation of Air Pollutant Emission Factors – Volume I: Stationary Point and Area Sources. AP-42. Fourth Edition.

[5] Picard, D.J., B.D. Ross, and D.W.H. Koon. 1992. A Detailed Inventory of CH 4 

# and VOC Emissions from Upstream Oil and Gas Operations in Alberta. Volume III: Results of Field Validation Program. Prepared by Clearstone Engineering Ltd.

for Canadian Petroleum Association.

[6] Hummel et al. 1996. Final Draft. Methane Emissions from the Natural Gas Industry. Volume 8: Equipment Leaks. Prepared by Radian International LLC for Gas Research Institute and U.S. Environmental Protection Agency.

[7] U.S. EPA. 1995. Protocol for Equipment Leak Emission Estimates. Publication

No. EPA-453/R-95-017. Section 2.

[8] Intergovernmental Panel on Climat e Change. 2000. Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories.

# 15 

# Glossary

Centrifugal Compressor Seal System A mechanical seal used to prevent the loss of process fluid past a rotating compressor shaft where the shaft penetrates the compressor housing.

Connectors - A connector is any flanged or threaded connection, ormechanical coupling, but excludes all welded or backwelded connections. If properly installed and maintained, a connector can provide essentially leak-free service for extended periods of time. However, there are many factors that can cause leakage problems to arise. Some of the
common causes include vibration, thermal stress and cycles, dirty or damaged contact surfaces, incorrect sealing material, improper tightening, misalignment, and

external abuse.

Control Valve A valve equipped with an actuator for automated operation to control flow, pressure, liquid level or other relevant
process parameter.

Leak Frequency The portion of a population of components that are determined to be leaking at the time of a leak detection

survey.

Open-ended Valves

and Lines - An open-ended valve is any valve that may release process fluids directly to the atmosphere in the event of leakage past the valve seat. The leakage may result from improper seating due to an obstruction or sludge accumulation, or because of a damaged or worn seat. An open-ended line is any segment of pipe that may be attached to such a valve that opens to the atmosphere at

the other end.

Few open-ended valves and lines are designed into process systems. However, actual numbers can be quite significant at some sites due to poor operating practices and various process modifications that may occur over

time.

Some common examples of instances where this type of source may occur are listed below:

• scrubber, compressor-unit, station and mainline blowdown valves,

• supply-gas valve for a gas-operated engine starter (i.e., where natural gas is the supply medium),

• instrument block valves where the instrument has been

# 16 removed for repair or other reasons, and

• purge or sampling points.

Pneumatic Controller A mechanism activated by an analog or digital signal that regulates the escape of a supply medium (e.g., compressed air or natural gas) to move mechanical

controls such as valves and levers.

Pressure Regulator A device used for maintaining a constant outlet pressure at a predetermined set point.

Pressure-Relief Valves - Pressure relief or safety valves are used to protect process piping and vessels from being accidentally over-pressured. They are spring loaded so that they are fully closed when the upstream pressure is below the set point, and only open when the set point is exceeded. Relief valves open in proportion to the amount of overpressure to provide modulated venting. Safety valves pop to a full-open positions on activation.

When relief or safety valves reseat after having been activated, they often leak because the original tight seat is not regained either due to damage of the seating surface or a build-up of foreign material on the seat plug. As a result, they are often responsible for fugitive emissions. Another problem develops if the operating pressure is too close to the set pressure, causing the valve to "simmer" or "pop" at the set pressure.

Gas that leaks from a pressure-relief valve may be detected at the end of the vent pipe (or horn). Additionally, there normally is a monitoring port located on the bottom

of the horn near the valve.

Reciprocating Compressor Packing Systems - Packings are used on reciprocating compressors to control leakage around the piston rod on each cylinder. Conventional packing systems have always been prone to leaking a certain amount, even under the best of conditions. According to one manufacturer, leakage from within the cylinder or through any of the various vents will

be on the order of 1.7 to 3.4 m 3 

# /h under normal conditions and for most gases. However, these rates may increase rapidly as normal wear and degradation of the system

occurs.

Standard Reference

Conditions - Most equipment manufacturers reference flow, concentration and equipment performance data at ISO

standard conditions of 15 ° C, 101.325 kPa, sea level and 0.0 percent relative humidity.

# 17 The following equation shows how to correct air

contaminant concentrations measured in the exhaust to 3 percent oxygen (15% excess air) for comparison and regulatory compliance purposes. To correct emission levels to 3 percent oxygen that are referenced to excess air levels other than 3 percent , use the following equation:

Total Hydrocarbons - All compounds containing at least one hydrogen atom and one carbon atom, with the exception of carbonates and

bicarbonates.

Total Organic Compounds (TOC) - TOC comprises all VOCs plus all non-reactive organic compounds (i.e., methane, ethane, methylene chloride, methyl chloroform, many fluorocarbons, and certain classes of per fluorocarbons).

Valves - There are three main locations on a typical valve where leakage may occur: (1) from the valve body and around the valve stem, (2) around the end connections, or (3) past the valve seat. Leaks of the first type are referred to as

valve leaks. Emissions from the end connections are classified as connector leaks. Leakage past the valve seat is only a potential source of emissions if the valve, or any downstream piping, is open to the atmosphere. This is referred to as an open-ended valve or line.

The potential leak points on each of the different types of valves are, as applicable, around the valve stem, body seals (e.g., where the bonnet bolts to the valve body, retainer connections), body fittings (e.g., grease nipples, bleed ports), packing guide, and any monitoring ports on the stem packing system. Typically, the valve-stem packing is the most likely of these parts to leak.

Vented Emissions - Vented emissions are releases to the atmosphere by design or by operational practice, and may occur on either

a continuous or intermittent basis. The most common causes or sources of these emissions are gas operated devices that use natural gas as the supply medium (e.g., compressor start motors, chemical injection and odourization pumps, instrument control loops, valve actuators, and some types of glycol circulation pumps), equipment blowdowns and purging activities, and venting of still-column off-gas by glycol dehydrators.

Volatile Organic Any compound of carbon, excluding carbon monoxide, and 

# (actual) ppm x (actual) O

- 21 3

- 21

= %) (3 ppm

2

# 18 Compounds (VOC) - carbon dioxide, which participates in atmospheric chemical reactions. This excludes methane, ethane, methylene chloride, methyl chloroform, many fluorocarbons, and certain classes of per fluorocarbons.

# 19 

# Appendix A: Average Emission Factors by Component Type

The figures in this appendix provide a graphical comparison of the average emission factors, by component type, developed based on the 1995/1996 GTC/EC data set, the 2005/2006 data, which includes the independent company studies and factors developed from the combined data set. Each figure provides both whisker plots showing the average emission factor and the 95 percent confidence limits, and bar graphs indicating the number of surveyed sources. The bar graph scale is on the left axis and the average emission rate in kg/hr/source is on the right axis.

The average emission factors for transmission facilities have increased for some categories and dropped for others. The most notable increases are in the factors for compressor seals, connectors, blowdowns and valves. In contrast, the distribution average emission factors, are virtually all lowe r than those from previous study. A tabular summary of change in the number of su rveyed sources, leak frequency and average emission factors between the 1995/1996 and 2005/2006 data sets is provided in Appendix F.

The whisker plots show the 95 percent confidence limits for each of the developed

emission factors. In a number of instanc es, the confidence limits have become wider rather that tighter despite the larger sample population. In these cases, the relative increase in the sample variance was greater than the relative increase in the sample population. Examination of the leaker data shows that the top few largest leakers in each component category create a highly skewed emission rate distribution. Not only do these leakers introduce a great deal of variance into the data set, which accounts for the wider confidence limits, but they also have a signi ficant impact on the average emission factor. Please refer to Appendix C for a discussion of the leaker data distribution.

# 20 0 20 40 60 80 100 120

T rans

mi

s s ion -

Co

mbine d

Tra ns miss

i o n -

2005

/ 2 0 0 6

T ra ns mis

si o n -

19

9 5 / 1 9 9 5Number of Sources

0 0.5 1 1.5 2 2.5Average Emission Rate (kg/h/src)



# Figure A-1 Average Emission Factors – Centrifugal Compressor Seals

0 20 40 60 80 100 120 140 160 180

T rans

mi

s s ion -

Co

mbine d

Tra ns miss

i o n -

2005

/ 2 0 0 6

T ra ns mis

si o n -

19

9 5 / 1 9 9 5Number of Sources

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2Average Emission Rate (kg/h/src)



# Figure A-2 Average Emission Factors – Reciprocating Compressor Seals

# 21 0 20000 40000 60000 80000 100000 120000 140000 160000

Distribution - Combined Distribution - 2005/200 6

Dis

tr ibution - 1 995/199 5 Distribution-CR - Combined

Di

str

ibuti

o n-CR - 2 00

5 /200

6

Di

str

ibuti

o n-CR - 1 99

5 /199

5

T ransm i s s ion - C o mbined

T ra nsmissi o n - 200 5 / 2 006

T ra nsmissi o n - 199 5 / 1 995Number of Sources

0 0.0001 0.0002 0.0003 0.0004 0.0005 0.0006 0.0007 0.0008 0.0009 0.001Average Leak Rate (kg/h/src)



# Figure A-3 Average Emission Factors – Connector

0 100 200 300 400 500 600 700 800 900

Distr

i b u ti o n - C o mbine d

Di

str

ib

u ti o n -

2 005

/2

00

6

Di

str

ibution - 1 995

/1

99

5 Distribution-CR - Combined

Distributi o n-CR - 2 005/200 6

T ransm i s si on - C o mbined

T ra ns mi

ssi

o n -

2 00

5 / 2 0 0 6

Tra

ns mi

s sio

n -

1 9 95/1

9 9 5Number of Sources

0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04Average Leak Rate (kg/h/src)



# Figure A-4 Average Emission Factors – Control Valve

# 22 0 10 20 30 40 50 60

D i str

i b u ti o n - C

o mb

in

e d

Di s tributi o n - 2005 /2

006

Di s tribution - 1995/1995

Trans mi

ssion - Co

mbine d

T ra ns

m i s si o n - 2

0 0 5 / 2 0 0 6

Tra ns miss

i o n -

1995

/ 1 9 9 5Number of Sources

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9Average Leak Rate (kg/h/src)



# Figure A-5 Average Emission Factors – Controller

0 50 100 150 200 250

D istribu ti o n - Co mb

ined

Di s tr i b u ti o n - 2

0 05

/2

0 0 6

T ra nsmi s si

o n - Co

mb

i n ed

T ra nsmi s si o n - 2

0 0 5 / 2 0 0 6

Transmi s sion - 1 9 95/1995Number of Sources

0 2 4 6 8 10 12 14 16Average Leak Rate (kg/h/src)



# Figure A-6 Average Emission Factors – Blowdown

# 23 0 200 400 600 800 1000 1200

Distr

i bution - Combine d

Di

str

ibution - 2 005/200 6

Di

stri

b u ti o n - 19

95

/1

9 95

Di

str

ibution-CR - Co mb

ined

Di

str

ibuti

o n-CR - 1 99

5 /199

5

T ra ns

m i s si

o n -

C

o mb

i n e d Transmission - 2005/2006

Tra

ns mi

s sio

n -

1 9 95/1

9 9 5Number of Sources

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2Average Leak Rate (kg/h/src)



# Figure A-7 Average Emission Factors – Open-Ended Line

0 20 40 60 80 100 120 140 160 180 200

Di stri

b u ti o n - Co

mb

i n ed

Di

stri

b u ti o n - 20

05

/2

0 06 Distribution - 1995/1995

Dis

tr ibution-CR - Com b ined

Di

str

i b u tio

n-CR - 2

00

5 /20

06

Distrib u tion-CR - 1995/1 9 95

T ra ns

m i s si

o n -

C

o mb

i n e d

T ra nsmissi o n - 200 5 / 2 006

Transmi s sion - 1 9 95/1995Number of Sources

0 0.05 0.1 0.15 0.2 0.25 0.3Average Leak Rate (kg/h/src)



# Figure A-8 Average Emission Factors – Orifice Meter

# 24 0 50 100 150 200 250 300 350 400 450 500

D i stribution - Combi n ed

Di

str

ib

u ti o n -

2 005

/2

00

6

Di

str

ibution - 1 995/199 5

Di

str

ib

u ti o n-CR - C

o mb

in

e d

Distributi o n-CR - 2 005/200 6

Di

str

i b uti

o n-CR - 1

99

5 /199

5 Transmission - C ombined

T ra nsmissi o n - 200 5 / 2 006

Transmi s sion - 1 9 95/199 5Number of Sources

0 0.000005 0.00001 0.000015 0.00002 0.000025 0.00003Average Leak Rate (kg/h/src)



# Figure A-9 Average Emission Factors – Other Flow Meter

0 200 400 600 800 1000 1200 1400

Di stributio n - Com b i n ed

Di

stri

b u ti o n -

20

05

/2

00

6

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stri

b u ti o n -

19

95

/1

99

5

D istri

b u ti o n -CR

- Combi n e d

Di

str

ibuti

o n-CR - 2 00

5 /200

6

Di

str

ibuti

o n-CR - 1 99

5 /199

5

Trans m ission - C ombine d

Transmi s sion - 2 0 05/2006

Tra

ns mi

s s i o n -

1 9 95

/ 1 9 9 5Number of Sources

0 0.005 0.01 0.015 0.02 0.025Average Leak Rate (kg/h/src)



# Figure A-10 Average Emission Factors – Pressure Regulator

# 25 0 100 200 300 400 500 600 700

Distr

i b u ti o n - C o mb

i ne

d

Dis

tr ibution - 2 005/200 6

Di

str

ib

u ti o n -

1 995

/1

99

5

Distri b ution-CR - Combi n ed

Di

str

i b uti

o n-CR - 2

00

5 /20

06

Distrib u tion-CR - 1995/1 9 95

T ransm i s s ion - C o mbined

Transmi s sion - 2 0 05/2006

T ra nsmissi o n - 199 5 / 1 995Number of Sources

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7Average Leak Rate (kg/h/src)



# Figure A-11 Average Emission Factors – Pressure Relief Valve

0 2000 4000 6000 8000 10000 12000 14000 16000 18000

Di stributio n - Com b i n ed

Di

stri

b u ti o n -

20

05

/2

00

6

Di

stri

b u ti o n -

19

95

/1

99

5

D istri

b u ti o n -CR

- Combi n e d

Di

str

ibuti

o n-CR - 2 00

5 /200

6

Di

str

ibuti

o n-CR - 1 99

5 /199

5

Trans m ission - C ombine d

Transmi s sion - 2 0 05/2006

Tra

ns mi

s s i o n -

1 9 95

/ 1 9 9 5Number of Sources

0 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008Average Leak Rate (kg/h/src)



# Figure A-12 Average Emission Factors – Valve

# 26 

# Appendix B: Comparison of Average Emission

Factors from Published Sources to Current Study by Component Type

The figures in this appendix provide a graphical comparison of the average emission factors developed based on a statistical analysis of combined data set of leak measurement and component counts collect ed during several field measurement programs, to those from the 1995/1996 and the 2005/2006 data sets and to published sources. The 95 percent confidence interv als on the average emission factors developed for the Canadian natural gas transmission and distribution industry are incorporated via whisker plots. This comparison is presented in tabular form in Table 3-2. To illustrate the relative magnitude of the emission factors for various component categories, the first figure shows the average factors for all categories on a Cartesian scale. The following four figures offer the emission factor comparisons on log scales in order to expand the emission rate range for various component categories.

0 1 2 3 4 5 6

B

l o w

d o w

n

C

o m

p r e s s o r S

e a l - C e n t

C

o m

p r e s s o r S

e a l - R e c i p

O

p e n - E

n d e d L

i n e C o n t r o l l e r

P

r e s s u r e R

e l i e f V

a l v e

O

r i f i c e M e t e r

C

o n t r o l V

a l v e V a l v e

P

r e s s u r e R

e g u l a t o r C

o n n e c t o r

O

t h e r F

l o w M e t e rAverage Emission Factor (kg/h/src)

U.S. Gas Production [1] Upstream Oil and Gas Operations [2] GRI Gas Transmission [3]

1995/1996 Gas Transmission [4] 2005/2006 Gas Transmission Combined Gas Transmission

1995/1996 Gas Distribution [4] 2005/2006 Gas Distribution Combined Gas Distribution

1995/1996 Gas Distribution-CR [4] 2005/2006 Gas Distribution-CR Combined Gas Distribution-CR



# Figure B-1 Comparison of Average Emission Factors – All Equipment Components

# 27 0.000001 0.00001 0.0001 0.001 0.01 0.1

Pressure Regulator Connector Other Flow MeterAverage Emission Factor (kg/h/src)

U.S. Gas Production [1]

Upstream Oil and Gas Operations [2]

GRI Gas Transmission [3]

1995/1996 Gas Transmission [4]

2005/2006 Gas Transmission

Combined Gas Transmission

1995/1996 Gas Distribution [4]

2005/2006 Gas Distribution

Combined Gas Distribution

1995/1996 Gas Distribution-CR [4]

2005/2006 Gas Distribution-CR

Combined Gas Distribution-CR



# Figure B-2 Comparison of Average Emission Factors – Pressure Regulator, Connector

and Other Flow Meter

0.000001 0.00001 0.0001 0.001 0.01 0.1

1

Orifice Meter Control Valve ValveAverage Emission Factor (kg/h/src)

U.S. Gas Production [1]

Upstream Oil and Gas Operations [2]

GRI Gas Transmission [3]

1995/1996 Gas Transmission [4]

2005/2006 Gas Transmission

Combined Gas Transmission

1995/1996 Gas Distribution [4]

2005/2006 Gas Distribution

Combined Gas Distribution

1995/1996 Gas Distribution-CR [4]

2005/2006 Gas Distribution-CR

Combined Gas Distribution-CR



# Figure B-3 Comparison of Average Emission Factors – Orifice Meter, Control Valve

and Valve

# 28 0.0001 0.001 0.01 0.1

1

Open-Ended Line Controller Pressure Relief ValveAverage Emission Factor (kg/h/src)

U.S. Gas Production [1]

Upstream Oil and Gas Operations [2]

GRI Gas Transmission [3]

1995/1996 Gas Transmission [4]

2005/2006 Gas Transmission

Combined Gas Transmission

1995/1996 Gas Distribution [4]

2005/2006 Gas Distribution

Combined Gas Distribution

1995/1996 Gas Distribution-CR [4]

2005/2006 Gas Distribution-CR

Combined Gas Distribution-CR



# Figure B-4 Comparison of Average Emission Factors – Open-Ended Line, Controller

and Pressure Relief Valve

0.001 0.01 0.1

1 10 100

Blowdown Compressor Seal - Cent Compressor Seal - RecipAverage Emission Factor (kg/h/src)

U.S. Gas Production [1]

Upstream Oil and Gas Operations [2]

GRI Gas Transmission [3]

1995/1996 Gas Transmission [4]

2005/2006 Gas Transmission

Combined Gas Transmission

1995/1996 Gas Distribution [4]

2005/2006 Gas Distribution

Combined Gas Distribution

1995/1996 Gas Distribution-CR [4]

2005/2006 Gas Distribution-CR

Combined Gas Distribution-CR



# Figure B-5 Comparison of Average Emission Factors – Blowdown, Centrifugal Compressor Seal and Reciprocating Compressor Seal

# 29 

# Appendix C: Leaker Data Distribution

The figures in this appendix show the data distribution for leak measurements, sorted by source type, for the transmission and distribution industries. The percent of the leaker population is on the X-axis and the span of the leak rate measurements is on the Y-axis. Absolute emission rates can be inferred from the mean, standard deviation and confidence limits provided on each graph. These graphs only represent the emissions from identified leakers, and the statistical values provided on the graphs are for the leaking equipment component population rather than the entire population of leaking and non-leaking equipment components. The populat ion of leaking equipment components at commercial and residential meter sets was not large enough to construct the corresponding figures for this industry sub-sector.

The leak frequencies provided in Table 3-1 show that the component population, for most component categories, is composed predominantly of non-leaking equipment components. The overall leak frequency at the facilities surveyed is approximately 1.9 percent. The distribution for most component types is very flat; therefore one is most likely to encounter non-leakers. The four exceptions to this are compressor seals, controllers, blowdowns and open-ended lines, all of which have leak frequencies exceeding 50 percent.

The distributions of leaker emission rates, shown in the following figures, illustrate a highly skewed population for most component categories. The emission rates from the vast majority of components in the leaker population are small and there are only a few large leakers in the component category, typically representing only 1 to 2 percent of the population. These top few leakers in each category have a significant impact on the average emission rate. Again, the major exceptions are compressor seals and controllers, which have a flat distribution. For these component types, the likelihood of encountering a small leaker and large leaker is similar.

# 30 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Compressor Seal - Cent Mean = 3.12E+00 (kg/h/src) Standard Deviation = 3.05E+00 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.00E+00 (kg/h/src)



# Figure C-1 Transmission Leaker Data Distri bution – Centrifugal Compressor Seals

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Compressor Seal - Recip Mean = 4.31E+00 (kg/h/src) Standard Deviation = 5.38E+00 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.76E+00 (kg/h/src)



# Figure C-2 Transmission Leaker Data Distri bution – Reciprocating Compressor Seals

# 31 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Connector Mean = 7.27E-02 (kg/h/src) Standard Deviation = 7.08E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 5.29E-02 (kg/h/src)



# Figure C-3 Transmission Leaker Data Distribution – Connector

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Control Valve Mean = 9.04E-02 (kg/h/src) Standard Deviation = 1.75E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 6.25E-02 (kg/h/src)



# Figure C-4 Transmission Leaker Data Distribution – Control Valve

# 32 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Controller Mean = 1.39E-01 (kg/h/src) Standard Deviation = 1.59E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 5.89E-02 (kg/h/src)



# Figure C-5 Transmission Leaker Data Distribution – Controller

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Blowdown Mean = 1.16E+01 (kg/h/src) Standard Deviation = 6.65E+01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.74E+01 (kg/h/src)



# Figure C-6 Transmission Leaker Data Distribution – Blowdown

# 33 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Open-Ended Line Mean = 4.15E-01 (kg/h/src) Standard Deviation = 1.16E+00 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 2.61E-01 (kg/h/src)



# Figure C-7 Transmission Leaker Data Distribution – Open-Ended Line

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Orifice Meter Mean = 4.06E-01 (kg/h/src) Standard Deviation = 1.16E+00 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 4.95E-01 (kg/h/src)



# Figure C-8 Transmission Leaker Data Distribution – Orifice Meter

# 34 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Pressure Regulator Mean = 1.67E-01 (kg/h/src) Standard Deviation = 7.46E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 2.44E-01 (kg/h/src)



# Figure C-9 Transmission Leaker Data Distribution – Pressure Regulator

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Pressure Relief Valve Mean = 7.64E-01 (kg/h/src) Standard Deviation = 3.36E+00 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 7.99E-01 (kg/h/src)



# Figure C-10 Transmission Leaker Data Distribution – Pressure Relief Valve

# 35 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Transmission - Valve Mean = 2.23E-01 (kg/h/src) Standard Deviation = 7.20E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 9.37E-02 (kg/h/src)



# Figure C-11 Transmission Leaker Data Distribution – Valve

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100 

### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Compressor Seal - Cent Mean = 2.94E-01 (kg/h/src) Standard Deviation = 1.53E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 9.46E-02 (kg/h/src)



# Figure C-12 Distribution Leaker Data Dist ribution – Centrifugal Compressor Seals

# 36 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Connector Mean = 5.85E-03 (kg/h/src) Standard Deviation = 5.32E-02 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 5.13E-03 (kg/h/src)



# Figure C-13 Distribution Leaker Data Distribution – Connector

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Control Valve Mean = 8.16E-02 (kg/h/src) Standard Deviation = 2.31E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 6.90E-02 (kg/h/src)



# Figure C-14 Leaker Data Distribution – Control Valve

# 37 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Blowdown Mean = 5.58E-02 (kg/h/src) Standard Deviation = 1.06E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.04E-01 (kg/h/src)



# Figure C-15 Distribution Leaker Data Distribution – Blowdown

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Open-Ended Line Mean = 2.48E-01 (kg/h/src) Standard Deviation = 5.47E-01 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 2.34E-01 (kg/h/src)



# Figure C-16 Distribution Leaker Data Distribution – Open-Ended Line

# 38 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Pressure Relief Valve Mean = 2.40E-03 (kg/h/src) Standard Deviation = 3.28E-03 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.18E-03 (kg/h/src)



# Figure C-17 Distribution Leaker Data Distribution – Pressure Relief Valve

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Pressure Regulator Mean = 8.70E-03 (kg/h/src) Standard Deviation = 2.08E-02 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 1.23E-02 (kg/h/src)



# Figure C-18 Distribution Leaker Data Distribution – Pressure Regulator

# 39 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of SpanPercent of Components 

### Data Distribution for Distribution - Valve Mean = 5.33E-03 (kg/h/src) Standard Deviation = 1.41E-02 (kg/h/src) 95 Percent Confidence Limits = Mean +/- 2.47E-03 (kg/h/src)



# Figure C-19 Distribution Leaker Data Distribution – Valve

# 40 

# Appendix D: Cumulative Leak Contributions

The following graphs for each equipment component type show the cumulative contribution of each leaking equipment com ponent to emissions from that source category. When the leakers are ranked from largest to smallest, as on these graphs, it becomes apparent that the top 10 percent of leakers typically contribute approximately 90 percent of the emissions. While this does vary somewhat by component category, the majority of the emissions in all component categories are contributed by a relatively small fraction of the leaking component popul ation. Only the data from the surveyed transmission facilities are presented by way of example, as the cumulative leak contribution graphs for components at distribution facilities are analogous.

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-1 Cumulative Leak Contributions fo r Transmission Facilities – All equipment
components

# 41 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-2 Cumulative Leak Contributions – Transmission – Centrifugal Compressor

Seals

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-3 Cumulative Leak Contributi ons – Transmission – Reciprocating Compressor Seals

# 42 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-4 Cumulative Leak Contribut ions – Transmission – Connector

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-5 Cumulative Leak Contributi ons – Transmission – Controller Vent

# 43 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-6 Cumulative Leak Contributi ons – Transmission – Control Valve

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-7 Cumulative Leak Contribut ions – Transmission – Blowdown

# 44 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-8 Cumulative Leak Contributi ons – Transmission – Open-Ended Line

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-9 Cumulative Leak Contributi ons – Transmission – Orifice Meter

# 45 0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-10 Cumulative Leak Contributi ons – Transmission – Pressure Relief

Valve

0 10 20 30 40 50 60 70 80 90 100

0 10 20 30 40 50 60 70 80 90 100



### Percent of ComponentsPercent of Emissions



# Figure D-11 Cumulative Leak Cont ributions – Transmission – Valve46Appendix E:Default Component Counts and Confidence IntervalsThe following tables present the default component count data and the 95 percent confidence limits (CL) on each value, along with thenumber of facilities or units surveyed. The 1995/1996 data set doesnot contain the detail required to evaluate confidence limits on thecomponent counts; consequently, the counts presented are basedon the 2005/2006 and independent company study data only.As has been noted, component counts can vary significantly basedon a number of factors. The results of component counts at thesurveyedfacilities show that certain component categories may not be present at all facilities of a given type. In these cases a fractional activity factorresults. To avoid confusion associated with fractional activity factors, entries in the table have been rounded to generate integer values. Incases of fractional activity factors less than 0.5, a value of zero has been entered to indicate that the component may be encounteredinfrequently at facilities of the given type. Since these fractional component types do not make a significant contribution ofoverall emissions,the impact on large scale emission inventories is considered extremely small.Table E-1 Confidence Limits on Equipment Schedules forGas Transmission FacilitiesBased on 2005/2006 MeasurementCampaign and Independent Company Studies Data Set.ComponentReceipt / SalesMeter StationMainline BlockValveReciprocatingCompressorUnitCentrifugalCompressorUnitCompressorStation YardPipingCompressorDischargeCoolerFacilitiesSurveyed168 13 25 29 21 9Average – – – 2 – –Upper CL – – – – – –CompressorSeal –CentrifugalLower CL – – – – – –Average – – 4 – – –Upper CL – – 5 – – –CompressorSeal –ReciprocatingLower CL – – 4 – – –Average 33 200 256 502 950 3527Upper CL 46 317 347 576 1210 4537ConnectorLower CL 20 84 165 429 689 251747Table E-1 Confidence Limits on Equipment Schedules forGas Transmission FacilitiesBased on 2005/2006 MeasurementCampaign and Independent Company Studies Data Set.ComponentReceipt / SalesMeter StationMainline BlockValveReciprocatingCompressorUnitCentrifugalCompressorUnitCompressorStation YardPipingCompressorDischargeCoolerAverage 0 0 1 5 13 0Upper CL 0 1 2 6 22 1Control ValveLower CL 0 0 0 4 4 0Average 0 0 0 0 1 –Upper CL 0 0 0 0 1 –ControllerLower CL 0 0 0 0 0 –Average 0 0 0 1 4 –Upper CL 0 0 0 1 5 –BlowdownLower CL 0 0 0 1 3 –Average 0 1 0 4 6 2Upper CL 0 1 0 6 9 3Open-EndedLineLower CL 0 1 0 3 3 1Average 0 – 1 0 2 –Upper CL 0 – 1 0 4 –Orifice MeterLower CL 0 – 0 0 0 –Average 1 0 – 0 1 –Upper CL 1 0 – 1 2 –Other FlowMeterLower CL 1 0 – 0 0 –Average 1 2 2 5 15 0Upper CL 1 5 3 6 20 1PressureRegulatorLower CL 1 0 2 3 10 0Average 0 0 2 3 8 0Upper CL 1 0 2 4 10 1Pressure ReliefValveLower CL 0 0 1 2 5 0Average 7 36 22 120 217 33Upper CL 9 53 27 140 289 46ValveLower CL 5 18 17 101 145 2048Table E-2 Confidence Limits on Equipment Schedules for Gas Distribution Facilities and Meter/Regulation Stations Based on2005/2006 Measurement Campaign and Independent Company Studies Data Set.ComponentIndustrialMeter SetGateStationDistrictRegulatorStationBorderMeterStationMainlineBlockValveReciprocatingCompressorUnitCentrifugalCompressorUnitCompressorStation YardPipingCompressorDischargeCoolerFacilities Surveyed 15 30 32 6 22 2 12 9 7Average – – – – – – 2 – –Upper CL – – – – – – – – –Compressor Seal –CentrifugalLower CL – – – – – – – – –Average – – – – – 5 – – –Upper CL – – – – – – – – –Compressor Seal –ReciprocatingLower CL – – – – – – – – –Average 111 353 181 381 142 163 430 1172 527Upper CL 152 427 248 – 207 – 523 1546 626ConnectorLower CL 70 280 113 – 77 – 336 799 428Average 0 2 1 1 1 1 5 19 0Upper CL 1 3 1 – 3 – 6 31 0Control ValveLower CL 0 0 0 – 0 – 4 7 0Average – 0 – – 0 – – – –Upper CL – 0 – – 0 – – – –ControllerLower CL – 0 – – 0 – – – –Average – – – 0 – 1 1 3 –Upper CL – – – – – – 1 7 –BlowdownLower CL – – – – – – 0 0 –Average – 0 0 4 1 4 5 22 –Upper CL – 1 1 – 1 – 8 37 –Open-Ended LineLower CL – 0 0 – 0 – 2 8 –Average 0 1 0 – 0 1 0 1 –Upper CL 0 1 0 – 0 – 1 2 –Orifice MeterLower CL 0 0 0 – 0 – 0 0 –Average 1 1 0 1 0 – 1 1 –Upper CL 2 1 0 – 1 – 1 2 –Other Flow MeterLower CL 1 0 0 – 0 – 0 0 –49Table E-2 Confidence Limits on Equipment Schedules for Gas Distribution Facilities and Meter/Regulation Stations Based on2005/2006 Measurement Campaign and Independent Company Studies Data Set.ComponentIndustrialMeter SetGateStationDistrictRegulatorStationBorderMeterStationMainlineBlockValveReciprocatingCompressorUnitCentrifugalCompressorUnitCompressorStation YardPipingCompressorDischargeCoolerAverage 4 12 8 8 2 1 3 18 –Upper CL 6 14 10 – 4 – 4 27 –Pressure RegulatorLower CL 2 10 5 – 1 – 1 8 –Average 0 3 2 3 1 2 2 18 1Upper CL 1 3 2 – 3 – 3 36 1Pressure ReliefValveLower CL 0 2 1 – 0 1 1 0 0Average 26 64 40 62 33 20 83 222 14Upper CL 37 80 53 – 54 – 102 321 19ValveLower CL 15 49 27 – 13 – 64 122 850Table E-3 Confidence Limits on Equipment Schedules for GasDistribution Commercial and Residential Meter Sites Based on2005/2006 Measurement Campaign Data Set.ComponentResidential Meter SetCommercial Meter SetFarm TapFacilities Surveyed 44 35 18Average 48 82 48Upper CL 69 100 60ConnectorLower CL 27 65 35Average 0 0 0Upper CL 0 0 0Control ValveLower CL 0 0 0Average – 0 –Upper CL – 0 –Orifice MeterLower CL – 0 –Average 1 2 0Upper CL 2 3 1Other Flow MeterLower CL 1 1 0Average 2 3 2Upper CL 2 5 3Pressure RegulatorLower CL 1 2 2Average 0 1 2Upper CL 0 2 3Pressure ReliefValveLower CL 0 0 1Average 8 14 13Upper CL 13 18 18ValveLower CL 4 10 751Appendix F: Changes observedfrom 1995/1996 to 2005/2006 data setsThe tables in this appendix offer a comparison, by industry sub-sector, of the average emission factors and confidence limits based on the1995/1996 data set, the 2005/2006 measurement campaign and independentcompany studies data set and the combined data set.In addition, tabular summaries of the magnitude of changes between the 1995/1996 study and subsequent measurement work, in terms ofnumber of sources encountered, leak frequencies and average emissions are provided.Table F-1 Comparison of Average Emission Factors (kg TOC/h/source) for GasTransmission Facilities.Combined Data Set2005/2006 Measurement Campaign +Independent Company Studies1995/1996 StudyComponentCategoryNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLCompressorSeal - Cent79 1.617E+00 2.181E+00 1.053E+0058 1.908E+00 2.634E+00 1.182E+0021 8.139E-01 1.397E+00 2.307E-01CompressorSeal - Recip 149 1.203E+00 1.714E+006.908E-01 113 1.375E+00 2.042E+00 7.074E-01 36 6.616E-01 9.184E-01 4.048E-01Connector 145829 4.471E-04 6.985E-04 1.957E-04 100761 5.297E-04 8.928E-04 1.667E-04 45068 2.624E-04 3.146E-04 2.102E-04Control Valve 782 1.650E-02 2.219E-021.082E-02 509 1.479E-02 1.911E-02 1.048E-02 273 1.969E-02 3.387E-02 5.514E-03Controller 50 2.371E-01 3.747E-01 9.941E-02 33 1.181E-01 1.708E-01 6.532E-02 17 4.681E-01 8.429E-01 9.330E-02Blowdown 219 3.405E+00 7.885E+00 0 117 5.556E+00 1.392E+01 0 102 9.369E-01 1.516E+00 3.576E-01Open-EndedLine928 9.183E-02 1.297E-01 5.395E-02286 1.104E-01 1.827E-01 3.816E-02642 8.354E-02 1.279E-01 3.924E-02Orifice Meter 185 4.863E-02 1.066E-01 0 81 1.068E-01 2.386E-01 0104 3.313E-03 4.694E-03 1.932E-03Other FlowMeter443 9.942E-06 1.966E-05 2.223E-07 177 1.131E-05 2.645E-050 266 9.034E-06 2.172E-05 0PressureRegulator 816 7.945E-03 1.882E-02 0 687 8.770E-03 2.167E-02 0 129 3.552E-03 6.208E-03 8.949E-04PressureRelief Valve 612 1.620E-01 2.950E-01 2.906E-02 426 1.225E-01 2.520E-01 0 186 2.524E-01 5.744E-01 0Valve 17029 4.131E-03 5.514E-03 2.748E-03 10877 5.257E-03 7.366E-03 3.148E-03 6152 2.140E-03 3.000E-03 1.280E-0352Table F-2 Changes from 1995/1996 to 2005/2006 Gas Transmission Data SetsPercent Change from 1995/1996 to 2005/2006Component CategoryNumber of SourcesSurveyedLeak Frequency Leaker Emission Factor Average Emission FactorCompressor Seal - Cent 176 -35 260 134Compressor Seal - Recip 214 -63 462 108Connector 124 -45 292 102Control Valve 86 -60 19 -25Controller 94 -15 -70 -75Blowdown 15 -35 811 493Open-Ended Line -55 -63 259 32Orifice Meter -22 28 4519 3124Other Flow Meter -33 -79 554 25Pressure Regulator 443 -68 743 147Pressure Relief Valve 129 -76 100 -51Valve 77 -48 473 14653Table F-3 Comparison of Average Emission Factors (kg TOC/h/source) for Gas Distribution Facilities and Meter/Regulation Stations.Combined Data Set2005/2006 Measurement Campaign +Independent Company Studies1995/1996 StudyComponentCategoryNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLCompressorSeal - Cent 24 1.223E-01 1.927E-01 5.191E-02 24 1.223E-011.927E-01 5.191E-02 – – – –CompressorSeal - Recip9 5.600E-04 1.789E-03 0 9 5.600E-04 1.789E-03 0 – – – –Connector 52051 8.227E-05 1.266E-04 3.792E-05 43466 7.687E-05 1.258E-04 2.791E-05 8585 1.096E-04 2.138E-04 5.472E-06Control Valve 605 1.949E-02 2.771E-021.127E-02 332 1.933E-02 2.875E-02 9.903E-03 273 1.969E-02 3.387E-02 5.514E-03Controller 25 3.997E-01 6.836E-011.158E-01 8 2.544E-01 6.599E-01 017 4.681E-01 8.429E-01 9.330E-02Blowdown 42 5.878E-03 1.591E-02 042 5.878E-03 1.591E-02 0 – – – –Open-EndedLine 969 6.077E-02 9.068E-02 3.086E-02 327 1.606E-02 3.216E-02 0642 8.355E-02 1.279E-01 3.924E-02Orifice Meter 142 3.011E-03 4.131E-031.890E-03 38 2.182E-03 3.987E-03 3.771E-04 104 3.313E-03 4.694E-03 1.932E-03Other FlowMeter 348 7.777E-06 1.752E-05 0 82 3.700E-06 7.634E-06 0 266 9.034E-06 2.172E-05 0PressureRegulator1323 6.549E-04 1.375E-03 0 954 1.218E-042.695E-04 0 369 2.033E-03 4.584E-03 0PressureRelief Valve472 3.944E-03 8.865E-03 0 3787.860E-04 1.044E-03 5.283E-04 94 1.664E-02 4.127E-02 0Valve 9817 5.607E-04 9.322E-04 1.892E-04 7832 4.217E-04 4.629E-04 3.805E-04 1985 1.109E-03 2.940E-03 054Table F-4 Changes from 1995/1996 to 2005/2006 Gas Distribution Data SetsPercent Change from 1995/1996 to 2005/2006Component CategoryNumber of SourcesSurveyedLeak Frequency Leaker Emission Factor Average Emission FactorCompressor Seal - Cent– – – –Compressor Seal - Recip– – – –Connector 406 17 -55 -30Control Valve 22 -12 8 -2Controller -53 -50 9 -46Blowdown– – – –Open-Ended Line -49 -91 114 -81Orifice Meter -63 -48 -50 -34Other Flow Meter -69 -100 -100 -59Pressure Regulator 159 -75 -79 -94Pressure Relief Valve 302 -50 -98 -95Valve 295 -58 -81 -6255Table F-5 Comparison of Average Emission Factors (kg TOC/h/source) for Commercial and Residential Gas Distribution Sites.Combined Data Set2005/2006 Measurement Campaign +Independent Company Studies1995/1996 StudyComponentCategoryNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLNumberofSourcesAverageEmissionFactor Upper CL Lower CLConnector 8616 4.467E-06 8.112E-06 8.226E-07 5846 3.469E-06 5.567E-06 1.371E-062770 6.573E-06 1.701E-05 0Control Valve 8 1.006E-02 2.466E-020 8 1.006E-02 2.466E-02 0 – – – –Open-EndedLine642 8.355E-02 1.279E-01 3.924E-02642 8.355E-02 1.279E-01 3.924E-02Orifice Meter 107 3.274E-03 4.630E-03 1.919E-03 3 1.925E-03 9.913E-030 104 3.313E-03 4.694E-03 1.932E-03Other FlowMeter405 7.203E-06 1.560E-05 0 1393.700E-06 6.714E-06 6.861E-07 266 9.034E-06 2.172E-05 0PressureRegulator 348 2.329E-05 4.633E-05 2.410E-07 2462.383E-05 5.352E-05 0 1022.197E-05 5.464E-05 0PressureRelief Valve78 1.749E-03 3.747E-03 0 72 1.872E-034.034E-03 0 6 2.717E-04 8.144E-04 0Valve 1340 2.173E-06 2.593E-06 1.753E-06 1081 2.100E-06 2.540E-06 1.660E-06 259 2.478E-06 3.641E-06 1.315E-06Table F-6 Changes from 1995/1996 to 2005/2006 Commercial and Residential Gas Distribution Data SetsPercent Change from 1995/1996 to 2005/2006Component CategoryNumber of SourcesSurveyedLeak Frequency Leaker Emission Factor Average Emission FactorConnector 111 -66 13 -47Control Valve– – – –Open-Ended Line– – – –Orifice Meter -97 -100 -100 -42Other Flow Meter -48 -100 -100 -59Pressure Regulator 141 -94 1747 9Pressure Relief Valve– – – –Valve 317 -100 -100 -15

# 56 

# Appendix G: Measured Emissions from 2005/2006 Field Campaign

Emissions from fugitive equipment lea ks identified and measured during the 2005/2006 field campaign total 13,536 × 10 3 

# m 3 

# /yr of lost product. The estimated value of these losses is $2,250,000 CDN/yr based on a natural gas value of $4.45 CDN/GJ. Table F-1 provides a summary of the measured emissions by type of facility, while Table F-2 lists the top 20 leaks encountered during the survey, along with the volume and value of product lost. Both tables indicate the significant contribution compressor stations, both odourized and unodourized, make to the overall emissions from the Canadian natural gas transmission and distribution industry. Compressor stations account for 98 percent of overall leakage and all 20 of the top leakers encountered during the 2005/2006 emission survey were located at compressor stations.

Table G-1 2005/2006 Measured Emissions by Facility Type

Facility Type Hydrocarbon Leak Rate (m 3 

# /hr) Contribution of Overall Leakage (%) Compressor Stations 1 

# 1513.7 97.96 Gate / Regulation Stations 14.61 0.95

Block / Control Valve Stations 13.11 0.85 Receipt / Meter Stations 3.66 0.24

1 

## Includes two LNG storage facilities.



# Table G-2 Top Twenty Leakers from 2005/2006 Emissions Survey

Facility Type Process Unit Source Hydrocarbon

Leak Rate

(m 3 

# /hr) Value of Lost Product ($/yr)

Compressor Stn. Station Blowdown Blowdown 656.2 $956,700 Compressor Stn. Cyclone Separator Blowdown 121.7 $177,378

Compressor Stn. Station Blowdown Pressure Relief

Valve 35.7 $52,098

Compressor Stn. Recip. Compressor Compressor Seal 28.8 $41,970 Compressor Stn. Recip. Compressor Compressor Seal 28.8 $41,970

Compressor Stn. Filter Unit Connector - Filter

Cover 22.9 $33,392

Compressor Stn. Recip. Compressor Compressor Seal 19.5 $28,475 Compressor Stn. Recip. Compressor Compressor Seal 19.2 $28,025

Compressor Stn. Station Fuel Gas

Vent Blowdown 18.3 $26,640

Compressor Stn. Cent. Compressor Compressor Seal 17.4 $25,367

Compressor Stn. Compressor

Blowdown Blowdown 15.9 $23,241

Compressor Stn. Cent. Compressor Compressor Seal 15.8 $22,994 Compressor Stn. Recip. Compressor Compressor Seal 14.0 $20,449 Compressor Stn. Cent. Compressor Compressor Seal 12.8 $18,619 Compressor Stn. Cent. Compressor Compressor Seal 12.1 $17,642 Compressor Stn. Cent. Compressor Compressor Seal 11.7 $17,103 Compressor Stn. Discharge Cooler Open-Ended Line 11.6 $16,939 Compressor Stn. Recip. Compressor Compressor Seal 11.3 $16,403 Compressor Stn. Cent. Compressor Compressor Seal 10.7 $15,545 Compressor Stn. Cent. Compressor Compressor Seal 10.6 $15,435