CEN/TS 17874:2022

Methodology for methane emissions quantification for gas transmission, distribution and storage systems and LNG terminals

This document describes a methodology to identify different types of methane emissions from the gas infrastructure and it explains, step by step, how to quantify each type of emission in a gas transmission, distribution and/or storage system and in an LNG terminal. Gas is considered any product with a high methane content  that is in gaseous form inside the respective gas infrastructure (e.g. natural gas, biogas or mixtures thereof with each other or with hydrogen).
Note of the editors: The inclusion of methane emissions in LNG terminals in the prTS is in clarification with CEN/TC 282. A Mode 4 cooperation has been established by CEN/TC 234 for this purpose.
Methane emission from utilisation, CNG/LNG fuelling stations, biomethane production and upgrading plants and LNG liquefaction and transport are not covered in this document, except if they are inside the covered asset (see Annex I on granularity).
NOTE 1: These principles can also be applied to other parts of the gas value chain.
The document specifies a bottom-up method of quantification of identified methane sources.
This quantification method requires splitting the gas systems into groups of assets, devices and components and indicating categories of emission that can be expected from these groups to determine the emission factors (EF) and the activity factors (AF).
Finally, a general method to calculate the uncertainties associated with the quantified amounts of emitted methane is described.
NOTE 2: Part of the methods of this document are retrieved by an international research program initiated by GERG for DSO.

Abschätzung von Methanemissionen für Gastransportund -verteilnetze

Evaluation des emissions de methane pour les réseaux de transport et de distribution de gaz

Metodologija za vrednotenje emisij metana za sisteme za prenos, distribucijo in skladiščenje ter terminale za utekočinjeni zemeljski plin

General Information

• Status: Not Published
• Publication Date: 02-Apr-2023
• ICS: 75.200 - Petroleum products and natural gas handling equipment
• Technical Committee: CEN/TC 234 - Gas infrastructure
• Drafting Committee: CEN/TC 234/WG 14 - Methane emissions
• Current Stage: 6055 - CEN Ratification completed (DOR) - Publishing
• Start Date: 30-Oct-2022
• Due Date: 11-Mar-2022
• Completion Date: 30-Oct-2022
• Ref Project: kSIST-TS FprCEN/TS 17874:2022 - Methodology for methane emissions quantification for gas transmission, distribution and storage systems and LNG terminals

Standards Content (Sample)

SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 17874:2022
01-september-2022
Metodologija za vrednotenje emisij metana za sisteme za prenos, distribucijo in
skladiščenje plina ter terminale za utekočinjeni zemeljski plin

Methodology for methane emissions quantification for gas transmission, distribution and

storage systems and LNG terminals
Abschätzung von Methanemissionen für Gastransportund -verteilnetze

Evaluation des emissions de methane pour les réseaux de transport et de distribution de

gaz
Ta slovenski standard je istoveten z: FprCEN/TS 17874
ICS:
75.200 Oprema za skladiščenje Petroleum products and
nafte, naftnih proizvodov in natural gas handling
zemeljskega plina equipment
kSIST-TS FprCEN/TS 17874:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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kSIST-TS FprCEN/TS 17874:2022
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 17874
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
July 2022
ICS 75.200
English Version
Methodology for methane emissions quantification for gas
transmission, distribution and storage systems and LNG
terminals

Méthodologie pour la quantification des émissions de Abschätzung von Methanemissionen für

méthane relatives aux réseaux de transmission, de Gastransportund -verteilnetze
distribution, aux stockages de gaz, et aux terminaux
GNL

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee

CEN/TC 234.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change

without notice and shall not be referred to as a Technical Specification.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 17874:2022 E

worldwide for CEN national Members.
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Content

European foreword ........................................................................................................................................... 5

Introduction ........................................................................................................................................................ 6

1 Scope ........................................................................................................................................................ 7

2 Normative references ........................................................................................................................ 7

3 Terms and definitions ....................................................................................................................... 7

4 Symbols and abbreviations .......................................................................................................... 14

5 Quantification of methane emission sources ......................................................................... 17

5.1 Strategy for quantification of methane emission from a gas system .................................... 17

5.1.1 General..................................................................................................................................................... 17

5.1.2 Materiality of emissions considerations ..................................................................................... 17

5.1.3 Starting point ......................................................................................................................................... 17

5.1.4 Other issues ........................................................................................................................................... 21

5.1.5 Building further knowledge of methane emissions ................................................................ 22

5.2 Emission types for gas systems .......................................................................................................... 23

5.3 Identification of emission sources. ................................................................................................... 24

5.3.1 General..................................................................................................................................................... 24

5.3.2 Identification of Emissions Sources for UGS .............................................................................. 26

6 Quantification .................................................................................................................................... 28

6.1 General concept of quantifications ................................................................................................... 28

6.2 Determination of Emission Factors (EF) ......................................................................................... 30

6.2.1 General..................................................................................................................................................... 30

6.2.2 Measurements ....................................................................................................................................... 30

6.2.3 EF estimations ....................................................................................................................................... 30

6.3 Determination of Activity Factor (AF) ............................................................................................. 31

6.4 Quantification of fugitive emissions ................................................................................................. 31

6.4.1 Fugitive emissions from permeation ............................................................................................ 31

6.4.2 Fugitive emissions due to connections (e.g. flanges, pipe equipment, valves, joints,

seals) ..................................................................................................................................................... 32

6.5 Quantification of vented emissions .................................................................................................. 36

6.5.1 General considerations ...................................................................................................................... 36

6.5.2 Operational emissions ....................................................................................................................... 37

6.6 Emissions from incidents ..................................................................................................................... 41

6.6.1 General..................................................................................................................................................... 41

6.6.2 Incidents on an individual basis ..................................................................................................... 42

6.6.3 Incidents grouping .............................................................................................................................. 42

6.6.4 Emission rate of incidents 𝑸𝑸𝑸𝑸 ........................................................................................................ 43

6.6.5 Duration of gas escape ....................................................................................................................... 43

6.6.5 Number of Incidents ........................................................................................................................... 44

6.7 Methane emissions from incomplete combustion ...................................................................... 44

6.7.1 General..................................................................................................................................................... 44

6.7.2 Measurement ......................................................................................................................................... 44

6.7.3 Emissions based on emission factor ............................................................................................. 44

7 Methods for detection and/or quantification (Informative) ...................................................... 46

8 Uncertainty calculations ........................................................................................................................... 55

8.1 Introduction .............................................................................................................................................. 55

8.2 Example of uncertainty calculation based on deterministic calculation ............................ 56

Annex A (informative) Permeation coefficients for plastic pipelines ........................................ 60

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Annex B (informative) Permeation of plastic pipelines – Influence of the soil temperature

................................................................................................................................................................. 63

Annex C (informative) Approaches to determine emission rates Q_V for underground leaks

................................................................................................................................................................. 65

C.1 Direct measurement of the emission rates .................................................................................... 65

C.2 Determination of soil coefficients and calculation of the emission rate from leak size and

pipeline pressure ............................................................................................................................. 65

Annex D (informative) Fugitive emissions: Approaches to determine leak duration .......... 67

D.1 Leak duration depending on the monitoring period and the maximum repair time .... 67

D.2 Leak duration by verified expert estimations .............................................................................. 67

Annex E (informative) Estimating volume flow rate for aerial leaks for different types of

flow conditions .................................................................................................................................. 68

E.1 General ........................................................................................................................................................ 68

E.2 Formulas for Subsonic Flow ................................................................................................................ 69

E.3 Formulas for Supersonic Flow ............................................................................................................ 70

E.4 Discharge coefficient (see [53]) ......................................................................................................... 70

Annex F (informative) Technologies for measurements of fugitive emissions on pipelines

................................................................................................................................................................. 71

F.1 General ........................................................................................................................................................ 71

F.2 Overview of technologies for Measurements on Facilities ....................................................... 72

F.2.1 General ..................................................................................................................................................... 72

F.2.2 Method of EN 15446 - Direct Measurement of the Emission Rates .................................... 72

F.3 Guidance for EF estimation .................................................................................................................. 73

Annex G (informative) Examples uncertainty calculation ............................................................. 75

G.1 Example 1: ........................................................................................................................................... 75

G.2 Example 2 ............................................................................................................................................ 76

G.3 Example 3 ............................................................................................................................................ 76

Annex H (informative) Terms used to define granularity .............................................................. 79

Annex I (informative) OGMP 2.0 level and tier description and correspondence ................. 80

Annex J (informative) Chapters linked to reporting categories .................................................. 83

J.1 Transmission system operator (TSO) ....................................................................................... 83

J.2 Underground Gas Storage Operator (UGS) ............................................................................. 88

J.3 LNG Terminal ..................................................................................................................................... 92

J.4 Distribution System Operator (DSO)......................................................................................... 94

Bibliography ..................................................................................................................................................... 97

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European foreword

This document (FprCEN/TS 17874:2022) has been prepared by Technical Committee CEN/TC 234 “Gas

infrastructure”, the secretariat of which is held by DIN.
This document is currently submitted to the Vote on TS.
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Introduction

Greenhouse gas (GHG) emissions, and more specifically methane (CH ) emissions are considered to have

an important impact on climate change. It is crucial for the gas industry to assess and to mitigate

methane emissions in the gas supply chain to support and contribute actively to European greenhouse

gas emission reduction targets.

Methane emissions management and reduction is a priority for the European natural gas industry. To

address this challenge a high level of transparency and reliability when reporting its emissions of

methane is required with harmonized standards.

A lack of harmonized standards to address the quantification of methane emissions from the natural gas

industry has been detected and, therefore, developed the present document that describes a

methodology, based on a source-level approach, to identify and to quantify all types of methane

emissions from transmission, distribution and storage systems and LNG terminals.

Some international initiatives have been recently launched with the intention to tackle the methane

emissions issue in the energy sector. Among those, the Oil and Gas Methane Partnership (OGMP), a

multi-stakeholder partnership supported by UNEP, stands out and intends to provide the industry with

a credible mechanism to address their methane emissions. The new OGMP standard commits

participating companies to increase the accuracy and granularity of their methane emissions reporting

for operated and non-operated assets.

Following the launch of the European methane strategy in October 2020, the European Commission is

encouraging the widespread adoption of the measurement and reporting framework developed under

the OGMP standard.

The quantification methodology described in this document can be used for OGMP reporting needs. It

should be a technical guideline for gas companies across Europe to support fast and harmonized

implementation of methane emissions quantification process.

This methodology is based in large parts on the document prepared by Marcogaz “Assessment of

methane emissions for gas Transmission and Distribution system operators” [18]. Marcogaz is the

Technical Association of the European Natural Gas industry.
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1 Scope

This document describes a methodology to identify different types of methane emissions from gas

infrastructure and it explains, step by step, how to quantify each type of emission in a gas transmission,

distribution and/or storage system and in an LNG terminal. Gas is considered any product with a high

methane content that is in gaseous form inside the respective gas infrastructure (e.g. natural gas, biogas

or mixtures thereof with each other or with hydrogen).

Methane emission from utilisation, CNG/LNG fuelling stations, biomethane production and upgrading

plants and LNG liquefaction and transport are not covered in this document, except if they are inside the

covered asset (see Annex I on granularity).

NOTE 1 These principles can also be applied to other parts of the gas value chain.

NOTE 2 Natural emission by the soil or seepage of methane due to gas field above or next to the storage reservoir

are not taken into account.

The document specifies a source-level method of quantification of identified methane sources.

NOTE 3 Source-level method - Emissions from each identified source are individually quantified. Total emissions

on a given asset are calculated by adding each type of emission source data.

This quantification method consists in splitting the gas systems into groups of assets, devices and

components and indicating categories of emission that can be expected from these groups to determine

the emission factors (EF) and the activity factors (AF). It comprises measurements of the amount of

methane emitted from different origin, estimation of emissions from groups of assets or calculation

based on available data. In case of individual measurements or calculations, the total emissions are

found by summing the quantified methane emissions.

Finally, a general method to calculate the uncertainties associated with the quantified amounts of

emitted methane is described.

NOTE 4 Part of the methods of this document are retrieved by an international research program initiated by

GERG for DSO.
2 Normative references
There are no normative references in this document.
3 Terms and definitions

For the purposes of this document, the terms and definitions given in CEN/TC 234 standards and the

following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— IEC Electropedia: available at http://www.electropedia.org/
— ISO Online browsing platform: available at http://www.iso.org/obp

NOTE The terms and definitions of CEN/TC 234 are compiled in CEN/TC 234 Doc N 776 [7]. Any new terms

used in CEN/TC 234 standards and related to hydrogen are to be added to CEN/TC 234 document.

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3.1
Activity Factor

numerical value describing the size of the population of emitting equipment such as length of pipelines,

number of valves (per type), number of pneumatic devices (per type), or the number of emitting events

such as number of operating vents, multiplied, if relevant, by the duration of the emission

Note 1 to entry: The question whether or not to multiply by the duration of the emission is examined later in this

document.
3.2
annulus
space between two strings of pipes or between the casing and the borehole
3.2
asset

part of the gas system owned by a natural gas company, comprising multiple devices that allows the

company to process, transport, store, and/or distribute gas (see Annex I)
3.3
block valve

valve used to isolate a segment of the main transmission pipeline for tie-in or maintenance purposes

Note 1 to entry: Block valves are located along each line to limit the amount of piping that may need to be

depressurized for tie-ins and maintenance, and to reduce the amount of gas that would be lost in the event of a

line break.
3.4
blow down valve

valve used to empty a gas pipeline section or a whole asset and, when actuated, initiates the gas

blowdown (e.g. when gas compressor units are shut down)
3.5
component
part or element of a larger whole, e.g.. flange, valve, connection (see Annex I)
3.6
connection

area of contact between two or more linked parts, axially or radially, normally sealed by mechanical

means in order to keep tightness
3.7
device

equipment (active or passive) related to a gas system and needed in order to keep the normal operation

of the network (see Annex I)

Note 1 to entry: It can be found as in-line equipment (like valves) or auxiliary equipment (like analysers).

Note 2 to entry: Methane emissions can appear from devices in unexpected way or as consequence of its function.

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3.8
control valve

modulating valve that controls either the flow rate or pressure through the pipeline and flowlines

Note 1 to entry: In the latter case, it is often referred to as a regulator station.

Note 2 to entry: High pressure gas from the pipeline may be used as the supply medium needed to energize the

valve actuator.
3.9
discharge coefficient

coefficient, which relates the actual flowrate to the theoretical flowrate through an opening and

accommodates the friction of the real flow as well as boundary layer effects (jet contraction)

Note 1 to entry: Needs to be determined experimentally and is nearly one for well-rounded openings.

Note 2 to entry: According to several data sources, a value of about 0.6 can be applied for sharp edged holes,

welding cracks or ruptures ([24], [25], [26]).
3.10
equipment

asset, device or component (see Annex I) of a gas system depending on the considered granularity

3.11
emission factor

factor that describes typical methane emissions of a component or part of the gas system (e.g. valve,

pipeline section) or from an event and can have units like [kg/km] or [kg/event]
3.12
fugitive emission
leakages due to tightness failure and permeation

Note 1 to entry: Some type of vented emissions, e.g. those from specific connections detected during survey, cannot

always be clearly distinguished from fugitive emissions. When reporting methane emission double counting

should be avoided.

Note 2 to entry: This term comprises the sum of various unaccounted channelled emissions, fugitive emissions and

area emissions.

Note 3 to entry: Permeation is leakage intrinsic to the use of permeable materials.

3.13
gas compressor station [5]
asset used for:
— transporting gas in pipelines;
— compressing gas from a pipeline to a gas storage facility or vice versa

Note 1 to entry: More than one of the above functions could be done simultaneously or alternatively.

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3.14
gas distribution system [7]

pipeline system for supplying natural gas comprising mains and service lines including piping above

and below ground and all other equipment necessary to supply the gas to the consumer

Note 1 to entry: Operating pressure is normally less than 16 bar.
3.15
gas transmission system [12]

gas transport network, which mainly contains high-pressure pipelines, other than an upstream pipeline

network and other than the part of high-pressure pipelines primarily used in the context of local

distribution of gas, with a view to its delivery to customers, but not including supply

Note 1 to entry: Transmission lines transport natural gas across long distances and occasionally across interstate

boundaries. They are connected to the distribution grid via city gate stations and/or pressure regulating stations.

Note 2 to entry: High-pressure gas transport over long distance including pipelines, compressor stations, metering

and regulating stations and a variety of above-ground facilities to support the overall system. Underground gas

storage and LNG terminals are excluded. Operating pressure is normally equal or greater than 16 bar.

3.16
gate station

facility located adjacent to a transmission grid where at least one of the following functions is

performed: pressure reduction, odorization, measurement or flow of gas through a splitter system for

distribution to different districts or areas
3.17
gas system [13]

any transmission networks, distribution networks, LNG facilities and/or storage facilities owned and/or

operated by a natural gas undertaking, including linepack and its facilities supplying ancillary services

and those of related undertakings necessary for providing access to transmission, distribution and LNG

3.18
incident [5]
unexpected occurrence, which could lead to an emergency situation
3.19
incident emission
methane emissions from unplanned events

Note 1 to entry: This will be from failures of the system due to third party activity, external factors, corrosion, etc.

3.20
incomplete combustion emissions

unburned methane in the exhaust gases from natural gas combustion devices, such as turbines, engines,

boilers or flares
3.21
LNG terminal

asset which is used either for the liquefaction of natural gas, exportation, or for the importation,

offloading, and re-gasification of LNG, and includes ancillary services and temporary storage necessary

for the re-gasification process and subsequent delivery to the transmission system, but does not include

any part of LNG terminals used for storage
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3.22
methane emission
release of methane to the atmosphere, whatever the origin, reason and duration
3.23
main lines of distribution [3]
pipework in a gas supply system to which service lines are connected
3.24
operational emission
methane emissions from normal or planned operating activities

1 to entry: This includes release through stacks; blow off valves, pressure release and purging of turbines

Note

and emissions due to normal maintenance inspection and control. Operational vents comprise planned venting

and purging of pipelines, which is usually done during commissioning, decommissioning, renewal and

maintenance of pipelines for safety reasons to prevent the risk of explosions. Pneumatic emissions are also

operational emissions.
3.25
permeation
penetration of a permeate (such as a liquid, gas, or vapour) through a solid

Note 1 to entry: In case of natural gas through pipelines made of polymer materials, it is directly related to the

pressure of the gas, intrinsic permeability of polymer materials and wall thickness. Polymers can be polyethylene,

polyamide or PVC.
3.26
pneumatic emission

emissions caused by gas operated valves, continuous as well as intermittent emissions

3.27
point of delivery [7]
point where the gas is transferred to the user

Note 1 to entry: This can be at a means of isolation (e.g. at the outlet of an LPG storage vessel) or at a meter

connection. For this document the point of delivery is typically nominated by the distribution system operator and

can be defined in National Regulations or Codes of Practices.
3.28
pressure regulating station [3]

asset comprising all the equipment including the inlet and outlet pipework as far as the isolating valves

and any structure within which the equipment is housed, used for gas pressure regulation and over-

pressure protection
3.29
purge factor
purge
factor, which accounts for the emissions caused by purge operations

Note 1 to entry: Purging of the air inside a pipeline or facility is necessary to mitigate the risk of explosions. The

purge factor herein does not refer to the amount of purge gas used but to the amount of the gas vented.

EXAMPLE: If purging is done with 1.5 times the pipeline volume, one volume stays in the pipe and 0.5 volumes are

vented to the atmosphere. The purge factor is in this case 0.5. If the actual purge factor is not known for an

operation, country specific factors should be used.
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3.30
purging [7]

process for safely removing air or inert gas from pipework and/or pipeline components and replacing

it with gas, or the reverse process
3.31
regulator [1]

device which reduces the gas pressure to a set value and maintains it within prescribed limits

3.32
service lines [3]

pipework from the main lines to the point of delivery of the gas into the installation pipework

Note
...