Chapter 8: Other Product Manufacture and Use

CHAPTER 8

OTHER PRODUCT MANUFACTURE
AND USE

2006 IPCC Guidelines for National Greenhouse Gas Inventories

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Volume 3: Industrial Processes and Product Use

Authors
Sections 8.1, 8.2, and 8.3
Deborah Ottinger Schaefer (USA)Friedrich Plöger (Germany), Winfried Schwarz (Germany), Sven Thesen (USA), Ewald Preisegger (Germany),
Ayite-Lo N. Ajavon (Togo), and Dadi Zhou (China)
Section 8.4
Nigel Harper (UK)

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Chapter 8: Other Product Manufacture and Use

Contents
8

Other Product Manufacture and Use .............................................................................................................8.6
8.1

Introduction ...........................................................................................................................................8.6

8.2

Emissions of SF6 and PFCs from electrical equipment .........................................................................8.6

8.2.1

Introduction ...................................................................................................................................8.6

8.2.2

Methodological issues ...................................................................................................................8.7

8.2.2.1

Choice of method.....................................................................................................................8.7

8.2.2.2

Choice of emission factors.....................................................................................................8.14

8.2.2.3

Choice of activity data ...........................................................................................................8.17

8.2.2.4

Completeness.........................................................................................................................8.19

8.2.2.5

Developing a consistent time series .......................................................................................8.20

8.2.3

Uncertainty assessment ...............................................................................................................8.20

8.2.4

Quality Assurance/Quality Control (QA/QC), Reporting and Documentation ...........................8.21

8.3

8.2.4.1

Quality Assurance/Quality Control........................................................................................8.21

8.2.4.2

Reporting and Documentation ...............................................................................................8.22

Use of SF6 and PFCs in other products ...............................................................................................8.23

8.3.1

Introduction .................................................................................................................................8.23

8.3.2

Methodological issues .................................................................................................................8.23

8.3.2.1

Choice of method...................................................................................................................8.23

8.3.2.2

Choice of emission factors.....................................................................................................8.32

8.3.2.3

Choice of activity data ...........................................................................................................8.33

8.3.2.4

Completeness.........................................................................................................................8.33

8.3.2.5

Developing a consistent time series .......................................................................................8.33

8.3.3

Uncertainty assessment ...............................................................................................................8.33

8.3.4

Quality Assurance/Quality Control (QA/QC), Reporting and Documentation ...........................8.33

8.4

8.3.4.1

Quality Assurance/Quality Control........................................................................................8.33

8.3.4.2

Reporting and Documentation ...............................................................................................8.34

N2O from product uses ........................................................................................................................8.35

8.4.1

Introduction .................................................................................................................................8.35

8.4.2

Methodological issues .................................................................................................................8.36

8.4.2.1

Choice of method...................................................................................................................8.36

8.4.2.2

Choice of emission factors.....................................................................................................8.36

8.4.2.3

Choice of activity data ...........................................................................................................8.37

8.4.2.4

Completeness.........................................................................................................................8.37

8.4.2.5

Developing a consistent time series .......................................................................................8.37

8.4.3
8.4.3.1

Uncertainty assessment ...............................................................................................................8.37
Emission factor uncertainties.................................................................................................8.37

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8.4.3.2

Activity data uncertainties .....................................................................................................8.38

8.4.4

Quality Assurance/Quality Control (QA/QC), Reporting and Documentation ...........................8.38

References.....................................................................................................................................................8.39

Annex 8A

Examples of Tier 3 national SF6 inventory systems ....................................................................8.41

Equations
Equation 8.1

Default emission factor method.............................................................................................8.8

Equation 8.2

Equipment disposal emissions under country-specific emission factor method....................8.9

Equation 8.3

Tier 3 total emissions...........................................................................................................8.10

Equation 8.4A Equipment manufacturing emissions - pure mass-balance ..................................................8.10
Equation 8.4B Equipment manufacturing emissions - hybrid .....................................................................8.11
Equation 8.5A Equipment installation emissions - pure mass-balance .......................................................8.11
Equation 8.5B Equipment installation emissions - hybrid...........................................................................8.11
Equation 8.6A Equipment use emissions - pure mass-balance....................................................................8.11
Equation 8.6B Equipment use emissions - hybrid.......................................................................................8.12
Equation 8.7A Equipment disposal and final use emissions - pure mass-balance.......................................8.12
Equation 8.7B Equipment disposal and final use emissions - hybrid..........................................................8.12
Equation 8.8

Emissions from recycling of SF6 .........................................................................................8.13

Equation 8.9

Emissions from destruction of SF6 ......................................................................................8.13

Equation 8.10 Utility-level mass-balance approach....................................................................................8.14
Equation 8.11 Retiring nameplate capacity ................................................................................................8.18
Equation 8.12 Emissions from AWACS (default emission actor)..............................................................8.24
Equation 8.13 Emissions from AWACS (user mass-balance)....................................................................8.25
Equation 8.14 University and research particle accelerator emissions (country-level) ..............................8.27
Equation 8.15 University and research particle accelerator emissions(accelerator-level emission factor) ......................................................................................8.28
Equation 8.16 Total research accelerator emissions ...................................................................................8.28
Equation 8.17 Research accelerator emissions (accelerator-level mass-balance).......................................8.28
Equation 8.18 Industrial/medical accelerator emissions (country-level) ....................................................8.30
Equation 8.19 Adiabatic property applications...........................................................................................8.31
Equation 8.20 Double-glazed windows: assembly .....................................................................................8.31
Equation 8.21 Double-glazed windows: use...............................................................................................8.31
Equation 8.22 Double-glazed windows: disposal .......................................................................................8.31
Equation 8.23 Prompt emissions.................................................................................................................8.32
Equation 8.24 N2O emissions from other product uses ..............................................................................8.36

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Chapter 8: Other Product Manufacture and Use

FiguresFigure 8.1

Decision tree for SF6 from electrical equipment....................................................................8.8

Figure 8.2

Decision tree for SF6 from AWACS ...................................................................................8.24

Figure 8.3

Decision tree for SF6 from research accelerators.................................................................8.27

Figure 8.4

Decision tree for industrial and medical particle accelerators .............................................8.29

Figure 8A.1

Example of Tier 3 approach: Germany, High-Voltage equipment ......................................8.42

Figure 8A.2

Example of Tier 3 approach: Germany, Medium-Voltage equipment ................................8.43

TablesTable 8.1

Avoiding double-counting or overlooking emissions: two examples..................................8.13

Table 8.2

Sealed pressure electrical equipment (MV Switchgear) containing SF6:
default emission factors .......................................................................................................8.15

Table 8.3

Closed pressure electrical equipment (HV Switchgear) containing SF6:
default emission factors .......................................................................................................8.16

Table 8.4

Gas insulated transformers containing SF6: default emission factors..................................8.16

Table 8.5

Uncertainties for default emission factors and lifetime .......................................................8.21

Table 8.6

Good practice reporting information for SF6 emissions
from electrical equipment by tier.........................................................................................8.22

Table 8.7SF6 emissions per plane per year .........................................................................................8.24

Table 8.8

National AWACS fleets ......................................................................................................8.25

Table 8.9

Average SF6 charge in a particle accelerator by process description...................................8.30

Table 8.10

Emission factor for each process description, (SF6 emissions from industrial
and medical particle accelerators) .......................................................................................8.30

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8 OTHER PRODUCT MANUFACTURE AND USE
8.1

INTRODUCTION

This chapter outlines methods for estimating emissions of sulphur hexafluoride (SF6) and perfluorocarbons(PFCs) from the manufacture and use of electrical equipment and a number of other products. It also provides
methods for estimating emissions of nitrous oxide (N2O) from several products. In most of these applications,
the SF6, PFC, or N2O is deliberately incorporated into the product to exploit one or more of the physicalproperties of the chemical, such as the high dielectric strength of SF6, the stability PFCs, and the anaesthetic
effect of N2O. However, the applications discussed here have a wide range of emission profiles, ranging fromimmediate and unavoidable release of all of the chemical (e.g., use of PFCs as atmospheric tracers) to largely
avoidable, delayed release from leak-tight products after 40 years of use (e.g., manufacture and use of sealedpressure electrical equipment). The estimation methods presented in the chapter have been tailored to reflect
these differences in emission profiles.
Section 8.2 details methods for estimating SF6 and PFC emissions from electrical equipment. Section 8.3 details
methods for estimating emissions from the manufacture and use of a wide variety of other industrial, commercial,and consumer products that contain SF6 and PFCs, excluding those discussed elsewhere in this volume (e.g.,
PFC emissions from electronics manufacturing, which are discussed in Chapter 6). (Please see the introduction
to Section 8.3 for the list of excluded sources.) Finally, Section 8.4 discusses methods for estimating N2Oemissions from anaesthetics, propellants, and other product uses.

8.2

EMISSIONS OF SF 6 AND PFCs FROMELECTRICAL EQUIPMENT

8.2.1

Introduction

Sulphur hexafluoride (SF6) is used for electrical insulation and current interruption in equipment used in thetransmission and distribution of electricity. Emissions occur at each phase of the equipment life cycle, including
manufacturing, installation, use, servicing, and disposal. Most of the SF6 used in electrical equipment is used in
gas insulated switchgear and substations (GIS) and in gas circuit breakers (GCB), though some SF6 is used inhigh voltage gas-insulated lines (GIL), outdoor gas-insulated instrument transformers and other equipment. The
aforementioned applications may be divided into two categories of containment. The first category is ‘Sealed
Pressure Systems’ or ‘Sealed-for-life Equipment’, which is defined as equipment that does not require any
refilling (topping up) with gas during its lifetime and which generally contains less than 5 kg of gas perfunctional unit. 1 Distribution equipment normally falls into this category. The second category is ‘Closed
Pressure Systems’, which is defined to include equipment that requires refilling (topping up) with gas during its
lifetime. This type of equipment generally contains between 5 and several hundred kg per functional unit.
Transmission equipment normally falls into this category. Both categories of equipment have lifetimes of morethan 30 to 40 years. In Asia, significant quantities of SF6 are used in gas-insulated power transformers (GIT).
Electrical equipment is the largest consumer and most important use of SF6, globally. It significantly contributes
to worldwide SF6 emissions. However, the importance of this source varies considerably from region to region
and from country to country. The emissions from this category depend not only on the installed (banked) or
consumed quantities of SF6, but also very much on the tightness of the products and the handling processes
applied. Regional average emission rates presently vary between far less than 1 percent to more than 10 percent.
In general, emission rates have declined significantly since 1995. Targeted industry actions have reduced
emissions by 50 to 90 percent in Europe and Asia (Ecofys, 2005; Aoyama, 2004). These actions include (1)1Formal definitions of ‘sealed-pressure system’ and ‘closed-pressure system’ are contained in International Electrotechnical Commission (IEC) Standard 60694. (IEC, 1996)

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Chapter 8: Other Product Manufacture and Use

designing equipment to require a smaller charge of SF6 and to be more leak tight and (2) improving handlingprocesses and handling equipment for all life cycle stages.2
In some regions (e.g., North America and Japan), perfluorocarbons (PFCs) are used as dielectrics and heattransfer fluids in power transformers. PFCs are also used for retrofitting CFC-113 cooled transformers. One PFC
used in this application is perfluorohexane (C6F14). In terms of both absolute and carbon-weighted emissions,
PFC emissions from electrical equipment are generally believed to be much smaller than SF6 emissions fromelectrical equipment; however, there may be regional exceptions to this pattern.

8.2.2

Methodological issues

8.2.2.1

C HOICE OF METHOD

Emissions of SF6 from electrical equipment can be estimated in a variety of ways with varying degrees ofcomplexity and data intensity. This section describes good practice for using a Tier 1 method (the default
emission-factor approach), a Tier 2 method (the country-specific emission-factor approach), and a Tier 3
method (a hybrid that can use either mass-balance or emission-factor approaches for different life cycle stages,
depending on country-specific circumstances). Generally, emissions estimates developed using the Tier 3
method, which is implemented at the facility level, will be the most accurate. Estimates developed using the Tier
1 method will be the least accurate.
As is true for other emission sources, the tier selected will depend on data availability and whether or not thecategory is key. Figure 8.1, Decision Tree for SF6 from Electrical Equipment, summarises the process forchoosing among Tiers 3, 2, and 1. Good practice in choosing between the mass-balance and emission-factor
variants of the Tier 3 approach is discussed in detail in Section 1.5 of Chapter 1. This choice will depend both ondata availability and on country-specific circumstances. As a first step in assessing the importance of SF6emissions from electrical equipment and the other categories discussed in this chapter, inventory compilers areencouraged to contact chemical producers and suppliers as well as electrical equipment manufacturers andutilities and/or their industry associations. These organisations can provide basic information on chemical
consumption and on equipment stocks and applications that can help the inventory compiler estimate emissions
and identify sources that merit further investigation. They can also provide important advice and support inestablishing more extensive data collection systems to support Tier 2 and Tier 3 estimates.

2

International Council on Large Electric Systems (CIGRE) has published a guide on SF6 handling, Guide for the Preparationof customized “Practical SF6 Handling Instructions,” Task Force B3.02.01, CIGRE Publication No.276, August 2005.
(CIGRE, 2005)

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Decision tree for SF 6 from electrical equipment 1

Figure 8.1

Start

Can anannual surveyof facilities that use SF6
be completed, gathering
data by lifecycle
stage?

Yes

Estimate emissions
using Tier 3 HybridLife-Cycle Approach.
Box 3: Tier 3NoAre
country-specificemission factors
available?

Yes

Estimate emissions
using Tier 2 CountrySpecific Emission
Factor Approach.
Box 2: Tier 2

Collect data forTier 2 or 3
approaches,3

No

Yes

Is theOther Product
Manufacture and Use a
key category2, and is
this subcategory
significant?

No

Estimate emissions
using the Tier 1
Default Emission
Factor Approach.
Box 1: Tier 1

Note:
1. In selecting an estimation method, it is good practice also to consider the criteria presented in Table 1.7, Chapter 1, Section 1.5 of thisvolume for choosing between the mass-balance and emission-factor variants of each tier.
2. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for
discussion of key categories and use of decision trees.
3. It is good practice to contact National/Regional associations of utilities/users and manufacturers to collect, check, andaggregate actual and historical data.

TIER 1 METHOD – DEFAULT EMISSION FACTORSThe Tier 1 approach is the simplest approach for estimating SF6 and PFC emissions from electrical equipment.
(Henceforth in this section, ‘SF6’ will be used to denote ‘SF6 and/or PFCs.’) In this method, emissions are
estimated by multiplying default regional emission factors by, as appropriate, the SF6 consumption of equipment
manufacturers and/or by the nameplate SF6 capacity of the equipment at each life cycle stage beyond
manufacturing in the country. The term Installation Emissions may be omitted if (1) installation emissions are
not expected to occur (i.e., for closed-pressure equipment) or (2) installation emissions are included in theemission factor for emissions from Manufacturing or Use. Default emission factors are given in Tables 8.2 to 8.4.
It is good practice to use the following equation:
EQUATION 8.1
DEFAULT EMISSION FACTOR METHOD
Total Emissions = Manufacturing Emissions + Equipment Installation Emissions+ Equipment Use Emissions + Equipment Disposal Emissions
Where:

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Manufacturing emissions = Manufacturing Emission Factor • Total SF6 consumption by equipment
manufacturers
Equipment installation emissions = Installation Emission Factor • Total nameplate capacity of new
equipment filled on site (not at the factory).
Equipment use emissions = Use Emission Factor • Total nameplate capacity of installed equipment. The‘use emission factor’ includes emissions due to leakage, servicing, and maintenance as well as
failures
Equipment disposal emissions = Total nameplate capacity of retiring equipment • Fraction of SF6
remaining at retirement

TIER 2 METHOD – COUNTRY-SPECIFIC EMISSION FACTOR METHODThe Tier 2 method uses the same basic equation as Tier 1, but requires reliable country-specific emission factors
for each life cycle stage. Country-specific emission factors will be more accurate because they reflect the unique
circumstances in which electrical equipment is used in a given country. In addition, if detailed data forequipment retirement are available, emissions due to retirement can be estimated more accurately. The
expression for Equipment Disposal Emissions in the Tier 2 method includes terms accounting for SF6 recovery
at retirement and disposal, as follows:
EQUATION 8.2
EQUIPMENT DISPOSAL EMISSIONS UNDER COUNTRY-SPECIFIC EMISSION FACTOR METHOD
Equipment disposal emissions = Total nameplate capacity of retiring equipment • Fraction of SF6
remaining at retirement • (1 – fraction of retiring equipment whose SF6 is recovered • recovery
efficiency • fraction of recovered SF6 recycled, reused with no further treatment, or destroyed*)*This final term is intended to account for emissions during chemical recycling and destruction.
Note that to be considered Tier 2, estimates must be developed using only country-specific emission factors.

TIER 3 HYBRID METHOD – EMISSIONS BY LIFE CYCLE STAGE OFEQUIPMENTThe Tier 3 method is the most accurate approach for estimating actual emissions of SF6 from electricalequipment. This method is detailed but flexible, accommodating a wide range of national circumstances. The
method is implemented at the facility level and includes separate equations for each phase of the life cycle ofequipment, including equipment manufacture, installation, use, and disposal. Depending on the type ofequipment, the life cycle stage, and country-specific circumstances, either a mass-balance approach or country(or facility-) specific emission factors may be used. In general, it is good practice to use the mass-balance
approach, except where (1) emission rates from a process are near or below the precision of the measurements
required for the mass-balance approach (e.g., 3 percent of nameplate capacity per year or less), (2) equipment isnever serviced during its lifetime (as is expected to be the case for sealed pressure equipment), or (3) equipment
stocks are growing very rapidly, as may be the case in countries where electrical equipment has been introduced
within the last 10-20 years.
The hybrid approach enhances accuracy by permitting use of the mass-balance approach for some processes andlife cycle stages and the emission-factor approach for other processes and life cycle stages. However, thecombination of different approaches also introduces opportunities for double-counting or overlooking emissions.
Inventory compilers need to be aware of this problem and take steps to avoid it. Table 8.1, Avoiding DoubleCounting or Overlooking Emissions, provides examples of both the problem and some potential solutions.
The annex to this chapter (Annex 8A) briefly describes an example of the Tier 3 approach as it has been appliedin Germany. This example is intended to illustrate rather than prescribe; the precise approach taken by any given
country will depend on country-specific circumstances.
Ideally, data are obtained for every equipment manufacturer, electricity transmission and distribution facility(utility), equipment disposer (which may be a manufacturer, electric utility, or other entity), and SF6 recycling or
destruction facility in the country, and the emissions of all manufacturers, utilities, disposers, and recycling or
destruction facilities are summed to develop the national estimate. The basic equation is:2006 IPCC Guidelines for National Greenhouse Gas Inventories

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EQUATION 8.3
TIER 3 TOTAL EMISSIONS
Total Emissions = ∑ Equipment Manufacturing Emissions+ ∑ Equipment Installation Emissions+ ∑ Equipment Use Emissions+ ∑ Equipment Disposal and Final Use Emissions+ ∑ Emissions from SF6 Recycling and Destruction

Where:
Equipment Manufacturing Emissions at the facility level can be estimated by Equations 8.4A and 8.4B.
Equipment Installation Emissions at the facility level can be estimated by Equations 8.5A and 8.5B.
Equipment Use Emissions at the facility level can be estimated by Equations 8.6A and 8.6B.
Equipment Disposal and Final Use Emissions at the facility level can be estimated by Equations 8.7A and
8.7B.
Emissions from SF6 Recycling and Destruction at the facility level can be estimated by Equations 8.8 and
8.9.
In the above equation, national emissions for each phase are equal to the sum of the emissions of all equipment
manufacturers, equipment users, equipment disposers, or SF6 recyclers/destroyers at that phase. In practice, it is
not always possible to obtain data for every facility; in these cases countries may use one of the extrapolation
methods discussed in Section 8.2.2.3, Choice of Activity Data.

Equipment manufacturing emissions
Equipment manufacturing emissions can be estimated using either a pure mass-balance approach or a mixture(hybrid) of a mass-balance approach for some processes and an emission-factor based approach for others. The
pure mass-balance approach is preferred except where a substantial fraction of a manufacturer’s emissions comefrom processes whose emission rates fall below the precision of the measurements required for the mass-balance
approach (e.g., 3 percent of nameplate capacity per year or less). In these cases, it is good practice to use
emission factors to estimate emissions from the processes with very low emission rates and to use the massbalance approach to estimate emissions from the other manufacturing processes.
Pure mass-balance approach: Using the pure mass-balance approach, the total emissions of each equipment
manufacturer can be estimated using the following equation:
EQUATION 8.4A
EQUIPMENT MANUFACTURING EMISSIONS - PURE MASS-BALANCE

Equipment Manufacturing Emissions = Decrease in SF6 Inventory + Acquisitions of SF6− Disbursements of SF6
Where:

Decrease in SF6 Inventory = SF6 stored in containers at the beginning of the year – SF6 stored incontainers at the end of the year
Acquisitions of SF6 = SF6 purchased from chemical producers or distributors in bulk + SF6 returned byequipment users or distributors with or inside of equipment + SF6 returned to site after off-site
recycling
Disbursements of SF6 = SF6 contained in new equipment delivered to customers + SF6 delivered toequipment users in containers + SF6 returned to suppliers + SF6 sent off-site for recycling + SF6
destroyed
Hybrid approach: This method first requires that manufacturers separate the gas flows associated with processes
for which the mass-balance approach will be used from the gas flows associated with processes for which theemission-factor approach will be used. Emissions from the former can then be estimated using the approach
outlined in Equation 8.4A. Emissions from the latter can be estimated by multiplying the total nameplate
capacity of equipment undergoing each process (e.g., filling) by the country- or facility-specific emission factor
for that process. Total emissions for each manufacturer are then estimated by summing the emissions from bothsets of processes, using the following equation:

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EQUATION 8.4B
EQUIPMENT MANUFACTURING EMISSIONS - HYBRID
Equipment Manufacturing Emissions = Equation 8.4 A+ ∑ Nameplate capacity of equipment undergoing each process *• Emission factor for that process* Excluding that covered by Equation 8.4A

Equipment installation emissions
Equipment installation emissions may be estimated using either a mass-balance or an emission-factor approach.
Again, the mass-balance approach is preferred except where emission rates are very low.
Pure Mass-balance approach: Using the mass-balance approach, the total emissions of each equipment installer
can be estimated using the following equation:
EQUATION 8.5A
EQUIPMENT INSTALLATION EMISSIONS - PURE MASS-BALANCE
Equipment Installation Emissions = SF6 used to fill equipment− Nameplate capacity of new equipment

Hybrid approach: This method first requires that users separate the gas flows associated with equipment for
which the mass-balance approach will be used from the gas flows associated with equipment for which theemission-factor approach will be used. Emissions from the former can then be estimated using the approach
outlined in Equation 8.5A. Emissions from the latter can be estimated by multiplying the newly installed
nameplate capacity of each equipment type by the country- or facility-specific installation emission factor forthat type. Total emissions for each installer are then estimated by summing the emissions from both sets ofequipments, using the following equation:
EQUATION 8.5B
EQUIPMENT INSTALLATION EMISSIONS - HYBRID

Equipment Installation Emissions = Equation 8.5A
+ ∑ Nameplate capacity of new equipment filled on site* • Installation emission factor* Excluding that covered by Equation 8.5A

Equipment use emissions
Equipment use emissions may be estimated using either a pure mass-balance or a hybrid approach. The puremass-balance approach is likely to be appropriate for countries where (1) electrical equipment that uses SF6 has
been in use for 10-20 years or more, and (2) emissions from sealed-pressure systems are likely to be negligible.
The hybrid approach is likely to be appropriate for other countries.
Pure mass-balance approach: Using the pure mass-balance approach, the total emissions of each equipment user
can be estimated using the following equation:
EQUATION 8.6A
EQUIPMENT USE EMISSIONS - PURE MASS-BALANCE
Equipment Use Emissions = SF6 used to recharge closed pressure equipment at servicing− SF6 recovered from closed pressure equipment at servicing

Hybrid approach: This method first requires that users separate the gas flows associated with equipment for
which the mass-balance approach will be used from the gas flows associated with equipment for which theemission-factor approach will be used. Emissions from the former can then be estimated using the approach
outlined in Equation 8.6A. Emissions from the latter can be estimated by multiplying the total nameplate
capacity of each type of equipment by the country- or facility-specific emission factor for that type of equipment.
The emission-factor approach is likely to be more accurate for sealed-pressure equipment everywhere and for all

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types of equipment in countries where electrical equipment has been used for less than 10-20 years. Total
emissions for each user are then estimated by summing the emissions from both sets of equipment, using thefollowing equation:
EQUATION 8.6B
EQUIPMENT USE EMISSIONS - HYBRID

Equipment Use Emissions = Equation 8.6A
+ ∑ Nameplate capacity of equipment installed * • Use emission factor* Excluding that covered by Equation 8.6A

Equipment disposal and final use emissions
Equipment disposal and final use emissions may be estimated using either a pure mass-balance or a hybrid
approach, based on country-specific circumstances. In both the pure mass-balance and hybrid approaches,
emissions from closed-pressure equipment are estimated using a mass-balance equation. In the pure massbalance approach, emissions from sealed-pressure systems are also estimated using a mass-balance equation. In
the hybrid approach, emissions from sealed-pressure systems are estimated using an emission-factor-based term.
Pure mass-balance approach: In countries where the gas-collection infrastructure (including recovery equipment,
technician training, and economic or legal incentives to recover) is not very well-developed or widely applied, it
is good practice to use the pure mass-balance approach, as follows:
EQUATION 8.7A
EQUIPMENT DISPOSAL AND FINAL USE EMISSIONS - PURE MASS-BALANCE
Disposal and Final Use Emissions = Emissions from closed⋅ pressure equipment+ Emissions from sealed⋅ pressure equipment (MB)Where:
Disposal and final use emissions from closed-pressure equipment = Nameplate capacity of retired closedpressure equipment – SF6 recovered from retired closed-pressure equipment, andDisposal and final use emissions from sealed-pressure equipment (MB) = Nameplate capacity of retired
sealed-pressure systems – SF6 recovered from retired sealed-pressure systems
Note that if the inventory compiler uses the emission-factor approach to estimate ‘use emissions’ from sealedpressure equipment, a term should be subtracted from the second equation to avoid double counting. See Table
8.1, Avoiding Double-Counting or Overlooking Emissions: Two Examples, for this term.
Hybrid approach: In countries where the disposal of equipment is well controlled and understood (i.e., where an
efficient gas collection infrastructure is in place) and where emissions from use of sealed-pressure equipment are
accounted for under ‘use’ above, the hybrid approach may be used, as follows:
EQUATION 8.7B
EQUIPMENT DISPOSAL AND FINAL USE EMISSIONS - HYBRID
Disposal and Final Use Emissions = Emissions from closed pressure equipment+ Emissions from sealed pressure equipment (EF )Where:
Disposal and final use emissions from closed-pressure equipment = Nameplate capacity of retired closedpressure equipment – SF6 recovered from retired closed-pressure equipment, andDisposal emissions from sealed-pressure equipment (EF) = [(Nameplate capacity of retired sealedpressure systems) – (Nameplate capacity of retired sealed-pressure systems • Use emission factor •Lifetime of equipment)] • (1 – fraction of retiring equipment whose SF6 is recovered • recovery
efficiency)
As noted above, emissions estimated using the above approach should be periodically checked, e.g., by using apure mass-balance approach and/or assessing recovery frequency and practices. Inventory compilers should pay
particular attention to the fraction of retiring equipment whose SF6 is recovered and to the fraction of the chargethat is recovered when recovery is performed (‘recovery efficiency’). Even in countries where it is the norm torecover SF6 from retiring equipment, some venting may occur, and the venting of just a few percent of the SF6 in

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Chapter 8: Other Product Manufacture and Use

retiring equipment will drive emission rates far above the minimum that is technically achievable and that would
otherwise be a reasonable basis for an emission factor.

Emissions from SF 6 recycling and destruction

Some SF6 emissions occur after the chemical is recovered. These emissions include (1) emissions associatedwith recycling of SF6, and (2) emissions associated with the destruction of SF6. (Emissions associated with the
shipment of SF6 to off-site recyclers or destruction facilities are considered negligible.) Emissions from recyclingof SF6 are generally expected to be small — on the order of less than one percent of the total quantity fed into therecycling process. However, these emissions may be higher if state-of-the art handling equipment and practices
are not used. In most cases, recycling is expected to occur on the site of the equipment manufacturer or user. In
other cases, recycling may take place at a centralised recycling facility that is not associated with a chemical
producer. Finally, recycling may take place on the premises of a chemical producer. Recycling emissions fromchemical producers will be accounted for under chemical production (see Section 3.10 of this volume) andshould not be included here.
Emissions associated with the destruction of SF6 depend on the destruction efficiency of the process and thequantity of SF6 fed into the process. Given the high stability and dissociation temperature of SF6, the destruction
efficiency may be as low as 90 percent. Thus, up to 10 percent of the SF6 fed into the destruction process could
be emitted. The quantity of gas fed into the destruction process is generally expected to be small compared tothat recycled. However, this may vary from country to country.
It is good practice to develop country-specific emission factors for recycling and destruction that are based on
full consideration of country-specific logistics and practices for SF6 recycling and destruction.
Emissions from recycling of SF6 may be estimated using the following equation:
EQUATION 8.8
EMISSIONS FROM RECYCLING OF SF6*

Emissions from Recycling = Recycling emission factor • Quantity SF6 fed into recycling process*Emissions from recycling that occurs at chemical production facilities should be excluded.
Emissions from destruction of SF6 may be estimated using the following equation:
EQUATION 8.9
EMISSIONS FROM DESTRUCTION OF SF6

Emissions from Destruction = Destruction emission factor • Quantity SF6 fed into destruction
process

TABLE 8.1
AVOIDING DOUBLE-COUNTING OR OVERLOOKING EMISSIONS: TWO EXAMPLES
Example 1 – Double Counting

Example 2 – Omission

Situation: An emission-factor approach is used toestimate emissions from sealed-pressure equipment
during use, and a mass-balance approach is used toestimate emissions during disposal of sealed-pressure
equipment.

Situation: A mass-balance approach is used to estimate
emissions during use of closed-pressure equipment, but
an emission-factor approach is used to estimate
emissions during disposal of closed-pressure.

Potential problem: Emissions during use may be
double-counted because some of the SF6 that is found tobe missing when the equipment is disposed has alreadybeen counted as emitted during use.

Potential problem: Emissions that occur between the
final servicing of the equipment and its disposal may beoverlooked. These ‘final use’ emissions may account fora significant fraction of total use emissions, particularly
if the equipment is refilled every 10 years or more.

Solution: Subtract lifetime use emissions (Nameplate
capacity of retired sealed-pressure systems • Useemission factor • Lifetime of equipment) from emissions
during disposal.

Solution: Use the mass-balance approach for both theuse and disposal phases of the closed-pressure equipment
life cycle.

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A special case of the Tier 3 method: the utility-level, pure mass-balance
approachCountries that satisfy the good practice criteria for using the pure mass-balance approach beyond equipment
manufacturing (i.e., countries where emissions during equipment installation, use, and disposal account for 3
percent or more of facility-level gas flows, where electrical equipment has been used for 10-20 years or more,
and where emissions from sealed-pressure equipment are negligible), may, with little or no loss of accuracy, usea simplified version of the Tier 3 method to estimate emissions during equipment use. When summed together
and reformulated in terms of facility-level gas flows, equations 8.5A, 8.6A, and 8.7A result in the following
equation:
EQUATION 8.10
UTILITY-LEVEL MASS-BALANCE APPROACH

User Emissions = Decrease in SF6 Inventory + Acquisitions of SF6 – Disbursements of SF6– Net Increase in the Nameplate Capacity of Equipment
Where:
Decrease in SF6 Inventory = SF6 stored in containers at the beginning of the year – SF6 stored incontainers at the end of the year
Acquisitions of SF6 = SF6 purchased from chemical producers or distributors in bulk + SF6 purchasedfrom equipment manufacturers or distributors with or inside of equipment + SF6 returned to site after
off-site recycling
Disbursements of SF6 = SF6 contained in equipment that is sold to other entities + SF6 returned tosuppliers + SF6 sent off-site for recycling + SF6 destroyed
Net Increase in Nameplate Capacity of Equipment = Nameplate Capacity of New Equipment –Nameplate Capacity of Retiring Equipment
Although the utility-level approach is less detailed than the full life cycle approach, it is simple, and for thosecountries whose national circumstances permit its use, it provides estimates that are closely related to actual gas
loss.

SF 6 EMISSIONS FROM MANUFACTURING OF ELECTRICAL COMPONENTS
Some electrical equipment components may contain 1 percent or less by weight of SF6 in the insulating mediumof the product. These components include but are not limited to medium voltage cast resin instrumenttransformers and high voltage bushings. In medium voltage (up to 52 kV) cast resin instrument transformers, SF6
is used to fill up micro-cavities in the resin insulation to improve the dielectric quality and durability of the
product. In High Voltage (above 52 kV) bushings, SF6 is used as the blowing agent for the polyurethane resin in
certain parts of the insulation system to improve the dielectric quality and durability of the product.
SF6 emissions solely result from the casting/blowing process for the solid insulation of the product. All SF6 used
is assumed to be emitted at the manufacturing stage. To estimate emissions from this source, the pure massbalance approach for equipment manufacturers (Equation 8.4A) may be used, setting the SF6 contained in new
equipment equal to zero.
Emission reduction measures focus on limiting losses/improving rate of recycling by suction devices and/or
improved casting processes. SF6 in this type of high voltage bushings may be replaced by another blowing agent
in the future.

8.2.2.2

C HOICE OF EMISSION FACTORS

Because emission rates can vary not only from country to country but from facility to facility, inventory
compilers using emission-factor based methods are encouraged to develop and use their own emission factors.
Surveying a representative sample of equipment manufacturers and utilities within the country is an effective
way to develop such factors. In general, it is good practice to document the evidence and reasoning supporting
the selected emission factors, and to review these factors at least every 5 years.
Factors that influence emission rates include the design of the equipment (which varies depending on when andwhere the equipment was manufactured), SF6-handling practices, availability of state-of-the-art handlingequipment, SF6 prices, and regulations (e.g., recovery requirements). Variation of any one of these can change
emission rates over time or among countries.

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Chapter 8: Other Product Manufacture and Use

TIER 1 METHOD
Suggested default emission factors have been developed for some regions based on recent research. These
factors are shown in Tables 8.2-8.4 below.
It is good practice to select default emission factors from countries and regions with equipment designs and SF6handling practices similar to those of the country whose emissions are being estimated. Because Japan andEurope supply most of the global demand for electrical equipment, equipment designs are likely to be similar to
those of either Japan or Europe. With the exception of the factors for the U.S., regional default emission factors
are those documented for 1995, i.e., before any special industry actions for emission reduction were
implemented. In Japan in 1995, approximately 70 percent of the SF6 used to test equipment during manufacture
was recovered, and a similar percentage was recovered during equipment maintenance for equipment rated 110
kv or higher. (The 70 percent recovery fraction reflected recovery from an initial pressure of about 5 bars
absolute to a final pressure of 1 to 1.5 bars absolute.) No gas was recovered from equipment rated lower than
110 kV (Maruyama et al., 2000). In Europe in 1995, gas supply systems for equipment manufacture were usuallydecentralised, and filling tubes were not self-closing. Gas was recovered to approximately 0.05 bars absoluteduring manufacturing and maintenance (Ecofys, 2005).

TABLE 8.2
SEALED PRESSURE ELECTRICAL EQUIPMENT (MV SWITCHGEAR) CONTAINING SF6:
DEFAULT EMISSION FACTORS

Phase

Manufacturing(Fraction SF6
Consumption by
Manufacturers)

Japan

c

Disposal(Fraction Nameplate Capacity of Disposed
Equipment)(Fraction per Year of
Nameplate Capacity of All
Equipment Installed)

Lifetime(years)Fraction of charge
remaining at retirement b

0.07

0.002

>35

0.93

0.29

0.007

Not reported

0.95

RegionEurope a

Use (Includes leakage,major failures/arc faults
and maintenance losses)aSource: ‘Reductions of SF6 Emissions from High and Medium Voltage Electrical Equipment in Europe,’ Ecofys, June, 2005.

bThis refers to the percentage of the original charge or nameplate capacity remaining in the equipment at end of life; it represents thefraction of the nameplate capacity potentially emitted before the equipment is recycled or disposed.

cBased on data reported by the Federation of Electric Power Companies (FEPC) and the Japan Electrical Manufacturers’ Association(JEMA) (FEPC and JEMA, 2004). These organisations did not distinguish among equipment types in reporting average emission
factors. The factors are therefore intended to be applied to all equipment types, including sealed pressure systems, closed pressure
systems, and gas-insulated transformers.

Note: The emission factors above reflect the practices and technologies in place in 1995, i.e., before mitigation measures were
implemented. References per footnotes a and c show how these developed further upon successive implementation of various voluntarymeasures later on. Another reference (Schwarz, 2006) relates state-of–the-art emission factors to mitigation measures in Germany.

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TABLE 8.3
CLOSED PRESSURE ELECTRICAL EQUIPMENT (HV SWITCHGEAR) CONTAINING SF6:
DEFAULT EMISSION FACTORS

Phase

Manufacturing(Fraction SF6
Consumption by
Manufacturers)

Japan
U.S.
a

d

Disposal(Fraction Nameplate Capacity of Disposed
Equipment)(Fraction per Year of
Nameplate Capacity of All
Equipment Installed)

Lifetime(years)Fraction of charge
remaining at retirement c

0.085b

0.026

>35

0.95

b

0.007

Not reported

0.95

>35

h

RegionEurope a

Use (Includes leakage,major failures/arc faults
and maintenance losses)

0.29

e

f

0.14

g

Source: ‘Reductions of SF6 Emissions from High and Medium Voltage Electrical Equipment in Europe,’ Ecofys, June, 2005.

b

Includes emissions from installationcThis refers to the percentage of the original charge or nameplate capacity remaining in the equipment at end of life; it represents thefraction of the nameplate capacity emitted before the equipment is recycled or disposed.

dBased on data eported by the Federation of Electric Power Companies (FEPC) and the Japan Electrical Manufacturers’ Association(JEMA) (FEPC and JEMA, 2004). These organisations reported average emission factors that include emissions from all equipment
types, including sealed pressure systems, closed pressure systems, and gas-insulated transformers.

e

From the U.S. Inventory of Greenhouse Gases and Sinks, 1990-2002. (U.S. EPA, 2004). Value is from 1999, first year for which
representative country-specific data were available.

f

No country-specific value available.

gIncludes emissions from installation.

hDisposal emissions are included in use emission factor in the US.

Note: The emission factors above reflect the practices and technologies in place in 1995, i.e., before mitigation measures were
implemented. References per footnotes a and d show how these developed further upon successive implementation of various voluntarymeasures later on. Schwarz (2006) relates state-of–the-art emission factors to mitigation measures in Germany.

TABLE 8.4
GAS INSULATED TRANSFORMERS CONTAINING SF6: DEFAULT EMISSION FACTORS
Phase

Manufacturing(Fraction SF6
Consumption by
Manufacturers)

RegionJapan b0.29

Use (Includes leakage,major failures/arc faults
and maintenance losses)

Disposal(Fraction Nameplate Capacity of Disposed
Equipment)(Fraction per Year of
Nameplate Capacity of All
Equipment Installed)

Lifetime(years)Fraction of charge
remaining at retirement a

0.007

Not reported

0.95

a

This refers to the percentage of the original charge or nameplate capacity remaining in the equipment at end of life; it represents thefraction of the nameplate capacity emitted before the equipment is recycled or disposedb

Based on data reported by the Federation of Electric Power Companies (FEPC) and the Japan Electrical Manufacturers’ Association(JEMA) (FEPC and JEMA, 2004). These organisations did not distinguish among equipment types in reporting average emission
factors. The factors are therefore intended to be applied to all equipment types, including sealed pressure systems, closed pressure
systems, and gas-insulated transformers.

Note: The emission factors above reflect the practices and technologies in place in 1995, i.e., before mitigation measures were
implemented. References per footnote b show how these developed further upon successive implementation of various voluntarymeasures later on. Schwarz (2006) relates state-of–the-art emission factors to mitigation measures in Germany.

TIER 2 METHOD
Emission factors for the Tier 2 method are generally developed on the basis of data collected from representative
manufacturers and utilities that track emissions by life cycle stage, essentially using the Tier 3, pure massbalance method at their facilities for at least one year. (The disposal emission factor should also account foremissions that occur downstream of the utility site, as discussed below.) These emissions by life cycle stage arethen divided by the corresponding SF6 consumption or equipment capacity at that life cycle stage (i.e., SF6
consumption for manufacturing emissions, total existing equipment capacity for use emissions, and retiring

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Chapter 8: Other Product Manufacture and Useequipment capacity for final use and disposal emissions) to develop emission factors. For example, to develop anemission factor for manufacturing, total emissions from the survey of manufacturers are summed and thendivided by the total SF6 consumption of surveyed manufacturers. This emission factor can then be applied to the
manufacturing sector as a whole, using national SF6 consumption by manufacturers. A similar approach can beused to estimate and apply emission factors for equipment use.
The emission factor for disposal should fully account for three factors: (1) the recovery frequency (the fraction ofequipment whose charge is recovered), (2) the recovery efficiency (the fraction of charge recovered whenrecovery is performed), and (3) the emissions from recycling and destruction of the recovered gas. The quantitiesin (1) and (2) will be automatically accounted for in emission factors based on use of the Tier 3 mass-balancemethod at representative utilities. However, the quantity in (3) reflects emissions that occur both on site anddownstream of the utility/user. Thus, it must be accounted for separately. See the Tier 3 Method discussion
below for guidance on estimating recycling and destruction emission factors.
The facility-level variant of the Tier 3 approach may also be used to develop emission factors, but these will beapplied at a more aggregated level, i.e., to equipment manufacturing and use (where the latter includes
installation, use, and disposal) rather than to each lifecycle stage.

TIER 3 METHOD
Because the Tier 3 method encourages the use of emission factors only when emission rates from processes arequite low (e.g., 3 percent of nameplate capacity per year or less) or when electrical equipment has only recently
been introduced into a country, emission factors for this method may be difficult to measure directly using a
mass-balance approach. To estimate Tier 3 emission factors, therefore, engineering studies may be used,
identifying potential leak points and loss mechanisms and assigning probabilities and emission rates to these.
Expected losses from service and maintenance should be factored into overall emission rates, as should losses
from rare but catastrophic events that result in the loss of most of the equipment’s charge. Past experience withsimilar processes and designs should be considered. To ascertain and verify emission factors for use, surveys ofequipment in the field may be carried out after several years of use, with the number of years determined by the
expected leak rate and the limit of detection of the measuring equipment. Manufacturer statistics on equipment
failure rates should be monitored to help ensure that catastrophic or gradual loss rates are not higher than
expected. Disposal emissions are extremely sensitive to recovery frequencies (the fraction of equipment whosecharge is recovered) and to recovery efficiencies (the fraction of charge recovered when recovery is performed,
which, due to time considerations, may be lower than what is technically achievable). Thus, these should bemonitored and documented carefully before establishing disposal emission factors.
Emission factors for recycling of recovered SF6 may be based on professional judgement. Emission factors for
destruction may be based on the rated destruction efficiency of the destruction technology, assuming that thetechnology is maintained and operated in a way that maintains its rated destruction efficiency.

8.2.2.3

C HOICE OF ACTIVITY DATA

The activity data necessary to carry out the various estimation methods may be gathered from chemical
manufacturers, equipment manufacturers, equipment users, and equipment disposers and/or their industry
associations in the country or the region. The best source(s) of data vary depending upon the method andnational circumstances.

TIER 1 METHOD
SF6 consumption by equipment manufacturers: SF6 consumption by equipment manufacturers can be estimatedusing information from the manufacturers on their purchases of SF6, their returns of SF6 to chemical producers,
and changes in their inventory of SF6 in containers. If information from equipment manufacturers is unavailable
or incomplete, information from chemical producers and/or distributors on their sales to equipment
manufacturers (less any returns) may be used.
Namep la te capacity of new and retiring equipment: Nameplate capacity can be estimated using one
or more of the following data sources: (1) information from equipment manufacturers/importers on the total
nameplate capacity of the equipment they manufacture or import and export, (2) information from utilities on the
total nameplate capacity of the equipment they install and retire each year, or (3) if information from (1) or (2) is
not available, information from chemical manufacturers/importers on their sales of SF6 to equipment
manufacturers. The first two data sources are preferable to the third, because gas sales to equipment
manufacturers will differ from the nameplate capacity of new equipment installed in the country, particularly if
equipment imports or exports are significant. In estimating the nameplate capacities of new and retiring
equipment, inventory compilers should include the nameplate capacity of imported equipment and exclude the2006 IPCC Guidelines for National Greenhouse Gas Inventories

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nameplate capacity of exported equipment. (See Section 7.5, Refrigeration, Box 7.1, Accounting for Imports andExports of Refrigerant and Equipment, for a full discussion of how to treat imports and exports in estimatingthese quantities. This guidance is directly applicable to this category.)In the case of retiring equipment, capacity or sales information should be historical, starting in the year when thecurrent year’s retiring equipment was built. Typical values for the lifetime of electrical equipment range from 30
to 40 years. If information on the total nameplate capacity of retiring equipment is not available, it can be
estimated from new nameplate capacity, using the estimated annual growth rate of equipment capacity. In
estimating the growth rate, it is good practice to consider both the number of pieces of equipment sold each year
3
and the average nameplate capacity of the equipment.
The following equation can be used to estimate retiring nameplate capacity, if this information is not available
directly:
EQUATION 8.11
RETIRING NAMEPLATE CAPACITY

Retiring Nameplate Capacity = New Nameplate Capacity / ( 1 + g )L
Where:
L = equipment lifetimeg = rate of growth
According to a 2004 global survey, the average annual growth rate of SF6 sales to equipment manufacturers
between 1970 and 2000 was approximately 9 percent. (Smythe, 2004). In the absence of country-specificinformation, a default factor of 9 percent may be used.
To ta l namep la te capacity of insta lle d equipment: The total nameplate capacity of equipment can be
estimated using the same data sources as are used to estimate the nameplate capacity for new and retiring
equipment. If data from equipment manufacturers is used, it should include data on sales over the full lifetime ofthe equipment (30 to 40 years).

TIER 2 METHOD
Quantities can be estimated as for Tier 1 above.

TIER 3 METHOD
To implement the Tier 3 method, information must be gathered at two levels. At the facility level, gas flows
must be tracked correctly according to the Tier 3 method. At the national level, information from facilities(manufacturers, users, and disposers of equipment) must be collected, checked, summed, and if necessary,
extrapolated to include estimates of emissions from facilities in the country that do not collect data. Guidance
regarding the information to be tracked by facilities is provided in the descriptions of the Tier 3 method above.
Gas consumption may be measured by weighing gas cylinders before and after filling or recovery operations orat the beginning and end of the year or by using flow meters (e.g., during equipment manufacturing). At thenational level, trade associations for equipment manufacturers and utilities can be very helpful in disseminatingknowledge to their members regarding the Tier 3 approach and in helping their members to track and report dataconsistently and transparently. Trade associations can also act as third parties to aggregate confidential orsensitive data so that it can be released (in aggregate) to the public. Where trade associations are not active,
national inventory compilers can facilitate the collection of information at the facility level, as well as thereporting and verification of this information, by developing model emission tracking protocols or by adopting
existing industry protocols that embody the Tier 3 approach. These protocols can then be distributed to the
manufacturers, users, and disposers of electrical equipment. Electronic protocols such as spreadsheets further
facilitate the tracking, documentation, and reporting of emissions and minimize opportunities for arithmetic error.
Because emission rates can vary from region to region and facility to facility, it is good practice to survey as
many facilities as practical. In addition to manufacturers and utilities, countries should survey industrial sites andother non-utility sites if these contribute substantially to emissions from electrical equipment. If the number offacilities in a country is large (e.g., over 50), it may be difficult to achieve complete reporting. In these cases,
countries may estimate emissions from non-reporting facilities by applying the Tier 2 method to these facilities

3

While the number of pieces of equipment sold each year has generally grown, the average nameplate capacity has generally
declined.

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Chapter 8: Other Product Manufacture and Useor by using alternative activity data as described in Chapter 2 of Volume 1, Approaches to Data Collection.
Sector-specific considerations in selecting and using alternative activity data are discussed below.
For sealed pressure equipment (which is widely dispersed among industrial users as well as utilities),
manufacturers and distributors are likely to be the best source of complete information on national bank sizes
and emission rates. To develop an accurate estimate, inventory compilers should survey manufacturers regarding
their sales of equipment between the present and the time when currently retiring equipment was installed, or, if
equipment has not yet begun to be retired, between the present and the time when the equipment was introduced
into the country.

Sector-specific considerations in selecting and using alternative activity data
for Tier 3
As discussed above, even when implementing a Tier 3 method it may not be possible to obtain data from all
facilities. To obtain complete coverage of facilities, it is possible to use alternative activity data. For estimating
emissions from non-reporting manufacturers, it may be possible to use the manufacturing capacity and/orcollective market share (in terms of functional units) of the non-reporting manufacturers. For estimating
emissions from non-reporting utilities, possible alternative data sets or drivers include (but are not limited to) the
length of transmission lines, the combined length of transmission and distribution lines, or the number ofsubstations of the non-reporting utilities. Transmission kilometres are likely to be a good predictor of emissions
where most SF6 is used in high voltage transmission equipment, as in the U.S. (A discussion of how transmission
kilometres are used to estimate emissions in the U.S. can be found in Volume 1, Chapter 2, Approaches to Data
Collection.) Where a high percentage of SF6 is used in medium voltage distribution equipment or in gasinsulated substations, one of the other types of data may be appropriate.
Wherever alternative data sets are used, it is important to derive emission factors from a representative set of
facilities to ensure that the resulting estimate of national SF6 emissions is unbiased. Note that more than one
factor may be appropriate, e.g., for different size utilities or for utilities in urban vs. rural locations. Because SF6
use and emission patterns can change over time, it is good practice to update the analysis and emission factor(s)at least every five years. (For example, emission rates may change as compact and leak-tight equipment replaces
larger, leakier equipment and as sealed pressure equipment grows in importance.) In some cases, countries may
be able to make use of emission factors developed in countries with similar electrical grids. In these cases, it isgood practice to document the similarities between the grids before applying the emission factor from the othercountry.

8.2.2.4

C OMPLETENESS

Completeness for this source category requires accounting for emissions during the manufacture, use, anddisposal of equipment, and during the recycling or destruction of SF6 recovered from equipment. Where Tier 3
methods are used, completeness requires that all significant SF6 users (manufacturers and utilities) be identified.
When facility-level emissions data are not available from all of these users, emission estimates should be
developed for them using one of the extrapolation methods described in Section 8.2.2.3, Choice of Activity Data.
In the manufacturing sector, this requires assessing emissions from:•

Manufacture of gas insulated switchgear (GIS), gas circuit breakers (GCB), high voltage gas-insulated lines(GIL), outdoor gas-insulated instrument transformers, reclosers, switches, and ring main units of both types(sealed and closed pressure systems, respectively up to and above 52 kV), and other equipment including
but not limited to cast resin instrument transformers and certain types of bushings using SF6 either as gas forthe casting process or as a blowing agent;•

Manufacturers of gas-insulated power transformers (GIT);•

Minor SF6 users, including equipment remakers and servicing companies;•

The SF6 distribution chain from producers and distributors to manufacturing facilities.

In the utility and disposal sector, this requires accounting for all SF6 losses associated with:•

New electrical equipment installations;•Leakage, refill, maintenance, and equipment failures;•

Disposal of discarded electrical equipment;•

Recycling or destruction of SF6 recovered from equipment (but recycling emissions from chemical
producers should be counted under chemical production, which is covered in Section 3.10 of this volume).

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It is good practice to identify and include industrial, military and small-utility applications if these are believed
to contribute substantially to total emissions from the electrical equipment source category.

8.2.2.5

D EVELOPING A CONSISTENT TIME SERIESWhen estimating emissions from equipment users over a time series, it is necessary to consider SF6 emissions
associated with the full set equipment at users’ sites for the years of interest. Thus, when using approaches basedon banks and emission-factors (e.g., the Tier 2 approach), countries will require information on the capacity andemission rate of equipment purchased and installed for 30 to 40 years preceding the years of interest.
In the user sector, if historical data are unavailable, good practice is to develop estimates using the top-down
method, i.e., develop a model based on professional judgement by industry experts and inventory compilers andthen calibrate as discussed below. Average leak rates for new equipment and the frequency of refill and routine
maintenance all decreased from 1970 to 1995, and this trend has continued to the present. It is not good practice
to apply current (post-2000) overall loss rates to historical years. Aggregate loss rates estimated from historicalsales can be used in this case as well.
On the manufacturing side, if historical data for developing base year emissions for 1990/1995 are not available,
the top-down method calibrated to more accurate estimates for current years may be applied. Since SF6 handlingpractices of equipment manufacturers have changed substantially since 1995 (e.g., more gas is recovered), it is
not good practice to apply current loss rates to historical estimates. Aggregate loss rates determined from global
and regional sales and emission analyses may assist in providing an unbiased estimate for earlier years. It is goodpractice to recalculate emissions according to the guidance provided in Volume 1, Chapter 5, with all
assumptions clearly documented.

8.2.3

Uncertainty assessment

When using the Tier 3 method, the resulting emissions estimates will have an accuracy of the order of ± 10
percent, and are likely to be more accurate than estimates developed using Tier 2 or Tier 1 methods.. If surveys
are incomplete, the associated uncertainty will be greater. Particular sources of uncertainty may include:•

SF6 exported by equipment manufacturers (either in equipment or separately in containers);•

SF6 imported by foreign equipment manufacturers (either in equipment or in containers);•

SF6 returned to foreign recycling facilities;•

Measurements of mass, density, and pressure (generally accurate to within one or two percent of the total
quantity massed, but if emission rates are low, this may be a substantial percentage of those rates);•

Emission factors;•

Time lag between emissions and servicing;4•Lifetime of the equipment;•

Regression error associated with any extrapolative approaches.

The estimated uncertainties in the default emission factors for the Tier 1 method are shown in Table 8.5,
Uncertainties for Default Emission Factors for SF6 Emissions from Electrical Equipment. These values are basedon the variation observed in emission factors in Europe. If the factors in Tables 8.2-8.4 are applied outside thecountries and/or regions in which they were developed, uncertainties will be greater.

4

See Chapter 1 of this volume for a discussion of this issue.

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Chapter 8: Other Product Manufacture and Use

TABLE 8.5
UNCERTAINTIES FOR DEFAULT EMISSION FACTORS AND LIFETIME
Phase

Manufacturing

Use (Includes leakage,major failures/arc faults
and maintenance losses)

Lifetime (years)

Fraction of charge
remaining at retirement

a

±20%

±20%

-20%/+40%

d

b

±30%

±30%

-10%/+40%

d

±30%

±30%

-10%/+40%d

Equip-ment Type
Sealed-Pressure

Closed-Pressure
Gas Insulated
Transformers c

Disposala

Estimated from ‘Reductions of SF6 Emissions from High and Medium Voltage Electrical Equipment in Europe,’ Ecofys, June, 2005;nouncertainties available from Japan; not relevant for USA..

b

Estimated from ‘Reductions of SF6 Emissions from High and Medium Voltage Electrical Equipment in Europe,’ Ecofys, June, 2005;
U.S. emission factors have higher uncertainty for manufacturing (±70%) and slightly lower uncertainty for use (±15%) (U.S.
Inventory of Greenhouse Gases and Sinks (U.S. EPA, 2004)). No uncertainties available from Japan.

c

Estimated by analogy with closed pressure systems; actual uncertainties may be somewhat higher. No uncertainties available fromJapan.

d

No uncertainties available on fraction of charge remaining at retirement.

8.2.4
8.2.4.1

Quality Assurance/Quality Control (QA/QC),
Reporting and Documentation
Q UALITY A SSURANCE /Q UALITY C ONTROL

It is good practice to conduct quality control checks as outlined in Volume 1, Chapter 6, and an expert review ofthe emissions estimates. Additional quality control checks as outlined in Volume 1, and quality assurance
procedures may also be applicable, particularly if higher tier methods are used to determine emissions from thissource category. Inventory compilers are encouraged to use higher tier QA/QC for key categories as identified inVolume 1, Chapter 4.
Additional procedures specific to electrical equipment are outlined below:

Comparison of emissions estimates using different approaches
Inventory compilers should sum the facility-level data used as part of a bottom-up, Tier 3 method and crosscheck the data against national level emissions calculated using country-level data (the Tier 2 method) and/or
country-level data with the IPCC default emission factors (the Tier 1 method). The Tier 2 method may similarly
be checked against the Tier 1 method. Countries may also compare their results to those derived using a countrylevel mass-balance approach, as described in Equations 7.3 and 7.9 of Chapter 7. If countries do not have
manufacturing facilities, they may also compare their estimates against potential emissions estimated using
national apparent consumption data.

Review of facility-level emissions dataIn all instances where site-specific emissions data are obtained through surveys, inventory compilers should
compare the emission rates between sites (adjusting for relative size or capacity) to identify significant outliers.
They should investigate any outliers to determine if the differences can be explained or if there is an error in thereported emissions. As noted in Section 8.2.2.3, national inventory compilers can facilitate both the collection
and verification of information at the facility level by distributing emission tracking protocols that embody the
Tier 3 approach. Electronic protocols such as spreadsheets are particularly useful, as they minimize opportunities
for arithmetic error. The calculations included in these protocols (whether electronic or not) can then be checked
after they are submitted.

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Comparison of emission rates with those of other countries
Inventory compilers should compare effective emission factors (loss rates) with values reported by othercountries in the region, or with defaults published in the scientific literature for equipment with a similar designand similar level of emissions control. Transparent reporting, as outlined above, is essential for making
international comparisons.

8.2.4.2

R EPORTING AND D OCUMENTATION

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Volume 1, Section 6.11. It is not practical to include all documentation in the national
inventory report. However, the inventory should include summaries of methods used and references to source
data such that the reported emissions estimates are transparent and steps in their calculation may be retraced.
Some examples of specific documentation and reporting relevant to this source category ensuring transparency
in reported emissions estimates are provided in Table 8.6, Good Practice Reporting Information for SF6
Emissions from Electrical Equipment by tier.
Confidentiality issues may arise where there are limited numbers of manufacturers or utilities. In these cases,
aggregated reporting for the total electrical equipment sector, or even total national SF6 applications, may benecessary. National or regional associations of users and manufacturers may be willing to collect, check, andaggregate data, particularly when they have collected such data historically. They can then report the aggregatedinformation to the inventory compiler, resolving the problem of confidentiality. If survey responses cannot bereleased as public information, third party review of survey data may be necessary to support data verification
efforts.

TABLE 8.6
GOOD PRACTICE REPORTING INFORMATION FOR SF6 EMISSIONS FROM ELECTRICAL EQUIPMENT BY TIER
Data

Tier 3

Annual, country-wide consumption of SF6 byequipment manufacturers

Tier 2Tier 1X

X

Nameplate capacity of new equipment

X

X

X

Nameplate capacity of existing equipment

X*

X

X

Nameplate capacity of retiring equipment

X

X

X

SF6 destroyedX

SF6 in inventory at beginning of year

X

SF6 in inventory at end of year

X

SF6 purchased by facilityX

SF6 sold or returned by facilityX

SF6 sent off-site for recycling

X

SF6 returned to site after recyclingX

SF6 used to fill new equipment

X

SF6 used to service equipment

X

SF6 recovered from retiring equipment

X

Emission/recovery factors

X*

X

Documentation for factors, if country-specific

X*

X*Required for some variants of the methods.

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Chapter 8: Other Product Manufacture and Use

8.3

USE OF SF 6 AND PFCs IN OTHER PRODUCTS

8.3.1

Introduction

This source category excludes the following source categories that are addressed elsewhere in the 2006
Guidelines:•

Production of SF6 and PFCs (Section 3.10);•

Production and use of electrical equipment (Section 8.2);•

Primary and secondary production of magnesium and aluminium (Chapter 4); and•Semiconductor and flat panel display manufacturing (Chapter 6).

Identified remaining applications in this source category include:•

SF6 and PFCs used in military applications, particularly SF6 used in airborne radar systems, e.g., AWACS(Airborne Warning and Control System), and PFCs used as heat transfer fluids in high-powered electronic
applications;•SF6 used in equipment in university and research particle accelerators;•

SF6 used in equipment in industrial and medical particle accelerators;•‘Adiabatic’ applications utilising the low permeability through rubber of SF6 and some PFCs, e.g., car tires
and sport shoe soles;•

SF6 used in sound-proof windows;•

PFCs used as heat transfer fluids in commercial and consumer applications;•

PFCs used in cosmetics and in medical applications;•

Other uses e.g. gas-air tracer in research and leak detectors.

8.3.2

Methodological issues

8.3.2.1

C HOICE OF METHOD

The good practice method is to use either consumption data from users of SF6 or PFCs or top-down import,
export and consumption data from national SF6 producers and distributors, disaggregated by major type of SF6 or
PFC application. Acquiring this data will entail a survey of all producers and distributors of SF6 and PFCs toidentify total net SF6 and PFC consumption. Once the data are obtained, the amount of SF6 and PFC consumed
by application in this source category should be estimated.

MILITARY APPLICATIONSSF 6 EMISSIONS FROM OPERATION OF AWACS
SF6 is used as an insulating medium in the radar systems of military reconnaissance planes of the Boeing E-3A
type, commonly known as AWACS. The purpose of the SF6 is to prevent electric flashovers in the hollow
conductors of the antenna, in which high voltages of more than 135 kV prevail. When the plane ascends, SF6 is
automatically released from the system and into the atmosphere to maintain the appropriate pressure difference
between the system and the outside air. When the plane descends, SF6 is automatically charged into the systemfrom an SF6 container on board. Most emissions occur during the pressure-balancing process on ascent, butemissions from system leakage can also occur during other phases of flight or during time on the ground. Annual
emissions per plane have been estimated to be 740 kg, while the charge of each system is approximately 13 kg.

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Volume 3: Industrial Processes and Product Use

Figure 8.2

Decision tree for SF 6 from AWACS
Start

Are detailed
acquisition anddisbursement data available
for this
category?

Yes

Use Mass-Balance
Tier 2 approach.
Box 2: Tier 2

No

Is the Other
Product Manufactureand Use a key category1, and is
this subcategory
significant?

No

Use Emission-Factor
Tier 1 approach.
Box 1: Tier 1

Yes
Collect data forTier 2 method.
Note:
1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for
discussion of key categories and use of decision trees.

Tier 1 method – SF 6 emissions per plane
If a country does not have data on SF6 consumption by its AWACS, it may use a per-plane emission factor toestimate emissions. An emission factor of 740 kg per plane per year is presented in Table 8.7 below; this figure
is based on estimates of SF6 emissions from NATO Boeing E-3As. Note that actual emissions per plane arestrongly influenced by the average number of sorties (take-offs) per plane per year. More frequent sorties willraise the emission rate above 740 kg/plane; less frequent sorties will lower it. Leakage rates during flight or
during time on the ground will also affect the emission rate.
EQUATION 8.12
EMISSIONS FROM AWACS (DEFAULT EMISSION ACTOR)

User Emissions = 740 kg • Number of planes in AWACS fleet

TABLE 8.7
SF6 EMISSIONS PER PLANE PER YEAR
Emissions per plane per year (kg SF6)740 kgUncertainty±100 kg

Source: Schwarz (2005)

Table 8.8 includes information on national AWACS fleets world wide (Boeing, 2005); like other activity data, it
may quickly go out of date. Countries are in the best position to know the numbers of planes in their AWACS
fleets.

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Chapter 8: Other Product Manufacture and Use

TABLE 8.8
NATIONAL AWACS FLEETSCountry/
Organisation

USA

Japan

France

UK

Other
NATO

Saudi
ArabiaTotal

No. AWACS

33

4

4

7

17

5

70

Source: Boeing (2005)

Tier 2 method – user mass-balance method
The most accurate method for estimating SF6 emissions from AWACS is to track SF6 consumption by thesystems. To do so, the following equations, which are similar to the utility-level variant of the Tier 3 method forelectrical equipment, may be used. Note that for AWACS, acquisitions and disbursements of SF6 containers arelikely to be considerably more important to the result than acquisitions and retirements of operating systems.
EQUATION 8.13
EMISSIONS FROM AWACS (USER MASS-BALANCE)

User Emissions = Decrease in SF6 Inventory + Acquisitions of SF6 – Disbursements of SF6 – Net
Increase in AWACS Fleet Charge
Where:
Decrease in SF6 Inventory = SF6 stored in containers at the beginning of the year – SF6 stored incontainers at the end of the year
Acquisitions of SF6 = SF6 purchased from chemical producers or distributors in bulk + SF6 purchasedfrom AWACS manufacturers or distributors with or inside of new planes + SF6 returned to site after
off-site recycling
Disbursements of SF6 = SF6 contained in AWACS that are transferred to other entities + SF6 returned tosuppliers + SF6 sent off-site for recycling + SF6 destroyed
Net Increase in AWACS Fleet Charge = 13 kg • (New AWACS – Retiring AWACS)

SF6 AND PFC EMISSIONS FROM OTHER MILITARY APPLICATIONSThere is wide range of military applications using PFCs or SF6.5 Military electronics are believed to be an
important and growing application of PFC heat transfer fluids, which are valued for their stability and dielectric
properties. The fluids are used in ground and airborne radar (klystrons), avionics, missile guidance systems,
ECM (Electronic Counter Measures), sonar, amphibious assault vehicles, other surveillance aircraft, lasers, SDI(Strategic Defense Initiative), and stealth aircraft. PFCs may also be used to cool electric motors, particularly inapplications where noise reduction is valued, e.g., in ships and submarines. The specific PFCs used in theseapplications are believed to be similar to those identified as heat transfer fluids in electronics manufacturing in
Chapter 6. Spray cooling, jet impingement cooling, and pool boiling appear to be the favoured systems for heatremoval. In all of these cooling applications, the PFC is contained in a closed system, and neither replacement
nor replenishment of the PFC liquid appears to be required. Thus, the greatest opportunities for emissions are the
manufacture, maintenance, and, especially, the disposal of the equipment.
SF6 is used in high-performance ground and airborne radar systems in their hollow conductors for transmissionof high-frequency energy pulses at high voltages from the klystron. Another application of SF6 is as an oxidantof lithium in Stored Chemical Energy Propulsion System (SCEPS), e.g., in naval torpedoes and in infrared
decoys (Koch, 2004). Apparently, these applications of SF6, like those of the PFC heat transfer fluids
enumerated above, are generally more or less enclosed, but servicing and testing procedures may lead toemission. The use of SF6 for the quieting of torpedo propellers has also been reported (NIST, 1997).
In addition, SF6 may be emitted as a by-product of the processing of nuclear material for the production of fueland nuclear warheads. SF6 is known to be emitted from neutralising excess fluorine during the production of
nuclear fuel for civilian applications (AREVA, 2005).
5David Harris and James Hildebrandt, “Spray Cooling Electrical and Electronic Equipment,” COTS Journal, November
2003; C. Shepherd Burton, “Uses and Air Emissions of Liquid PFC Heat Transfer Fluids from the Electronics Sector,”
Draft report prepared for Scott C. Bartos, U.S. Environmental Protection Agency.

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Although it is believed that the total amounts of SF6 and PFCs consumed and emitted in this sector may besignificant, no data on quantities are publicly available so far. Therefore, inventory compilers should try tocollect further information from the relevant authorities and, if possible, their suppliers. As noted above, thegreatest opportunities for emissions from many of these applications appear to be the manufacture, maintenance,and disposal of the equipment. Thus, if inventory compilers can acquire information on emission rates during the
manufacture, maintenance, and disposal of the equipment, along with the quantities of equipment manufactured,in use, and disposed, they can use the Tier 2 or Tier 3 method for electrical equipment to estimate emissions. For
applications with different emissions profiles (e.g., prompt emissions), the appropriate equation from Section 8.2
may be used.

SF 6 EMISSIONS FROM UNIVERSITY AND RESEARCH PARTICLEACCELERATORS
SF6 is used in university and research operated particle accelerators as an insulating gas. Typically, high voltage
equipment is contained and operated within a vessel filled with SF6 at a pressure exceeding atmospheric pressure.
Charges range from five kilograms to over ten thousand kilograms, with typical charges falling between 500 and
3 000 kg. When the equipment requires maintenance, the SF6 is transferred into storage tanks. SF6 losses occur
primarily during gas recovery and transfer, when pressure relief valves are actuated, and through slow leaks.
Based on two recent studies annual SF6 losses range between 5 and 7 percent of vessel capacity per year andgenerally depend on the vessel opening frequency plus the efficiency of the recovery and transfer equipment.
World banked capacity is roughly estimated to be 500 tonnes with annual SF6 emissions of 35 tonnes.
Switzerland has developed a voluntary program to reduce SF6 emissions from particle accelerators. Suggestions
and techniques for reducing SF6 emissions from these sources exist.

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Chapter 8: Other Product Manufacture and Use

Figure 8.3

Decision tree for SF 6 from research accelerators
Start

Are
detailed acquisitionand disbursement data
available for thiscategory?

Yes

Use Accelerator-Level
Mass-Balance approach.
Box 3: Tier 3

NoAredata on individual
accelerator charges
available?

Yes

Use Accelerator-Level
Emission-Factor approach.
Box 2: Tier 2

No
Is theOther Product
Manufacture and Use
a key category1, and is thissubcategory
significant?

No

Use Country-Level
approach.
Box 1: Tier 1

Yes
Collect data for Tier 3
or Tier 2 method.
Note:
1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for
discussion of key categories and use of decision trees.

Tier 1 method – country-level method
In cases where individual user accelerator charge data is unavailable, one extremely rough method involves
determining the total number of university and research particle accelerators in the country and using several
factors to determine the country-level annual emission rate as noted in Equation 8.14. For this Tier 1 method, theonly data that requires collection is the total number of university and research particle accelerators in the given
country.
EQUATION 8.14
UNIVERSITY AND RESEARCH PARTICLE ACCELERATOR EMISSIONS (COUNTRY-LEVEL)

Emissions = (Number of university and research particle accelerators in the country) • (SF6 Use
Factor) • (SF6 Charge Factor, kg) • (SF6 university and research particle accelerator Emission Factor)
Where:
Number of university and research particle accelerators in the country = The total number of university
and research particle accelerators in the country. This rough method does not require countries todetermine the number of accelerators that use SF6. To determine if a country has a particle
accelerator, go to http://www-elsa.physik.uni-bonn.de/Informationen/accelerator_list.html

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SF6 Use Factor = 0.33 Approximately one third of university and research particle accelerators use SF6 as
an insulator.
SF6 Charge Factor = 2400 kg, SF6, the average SF6 charge in a university and research particle
accelerator.
SF6 university and research particle accelerator Emission Factor = 0.07, the average annual university
and research particle accelerator emission rate as a fraction of the total charge.

Tier 2 method – accelerator-level emission-factor approach
If data on the quantity of SF6 contained within each university and research accelerator are available, a default
emission factor of 7 percent may be multiplied by the total SF6 charge contained in university and researchaccelerators in the country. The total country SF6 emission rate from university and research accelerators istherefore calculated from Equation 8.15.
EQUATION 8.15
UNIVERSITY AND RESEARCH PARTICLE ACCELERATOR EMISSIONS (ACCELERATOR-LEVELEMISSION FACTOR)

Total Emissions = SF6 university and research particle accelerator Emission Factor• ∑ Individual Accelerator Charges
Where:
SF6 university and research particle accelerator Emission Factor = 0.07, the average annual university
and research particle accelerator emission rate as a fraction of the total charge.
Individual User Accelerator Charges = SF6 contained within each university and research accelerator.

Tier 3 method –accelerator-level mass-balance method
SF6 emissions from university and research facilities operating particle accelerators may be most accurately
determined at the user level on an accelerator-by-accelerator basis. Emission calculations are estimated bytracking accelerator charge as well as SF6 consumption and disposal. As detailed in Equation 8.16, the total
emissions are equal to the sum of the individual users’ emissions. Note, under this method, as the overall SF6emission rate from particle accelerators is small compared to other SF6 uses, the associated SF6 lost in
manufacturing is considered negligible and is not included in the calculation.
EQUATION 8.16
TOTAL RESEARCH ACCELERATOR EMISSIONS
Total Emissions = ∑ Individual Accelerator Emissions

Each particle accelerator’s emissions can be calculated as follows:
EQUATION 8.17
RESEARCH ACCELERATOR EMISSIONS (ACCELERATOR-LEVEL MASS-BALANCE)

Accelerator Emissions = Decrease in SF6 Inventory + Acquisitions of SF6 – Disbursements of SF6– Net Increase in Accelerator Charge
Where:
Decrease in SF6 Inventory = SF6 stored in containers at the beginning of the year – SF6 stored incontainers at the end of the year
Acquisitions of SF6 = SF6 purchased from chemical producers or distributors in bulk + SF6 purchasedfrom accelerator manufacturers or distributors with or inside of new accelerator components + SF6
returned to site after off-site recycling
Disbursements of SF6 = SF6 contained in components transferred to other entities + SF6 returned tosuppliers + SF6 sent off-site for recycling + SF6 destroyed
Net Increase in Accelerator Charge = SF6 Charge of New Components – SF6 Charge of Retiring
Components

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Chapter 8: Other Product Manufacture and Use

SF 6 EMISSIONS FROM INDUSTRIAL AND MEDICAL PARTICLEACCELERATORS
SF6 is used as an insulating gas in two types of industrial particle accelerators (low and high voltage) and also in
medical (cancer therapy) particle accelerators, as is the case for university and research particle accelerators.
However, the emission and charge factors for industrial and medical particle accelerators are different from thoseof university and research accelerators, as discussed below.
Global banked capacity for industrial particle accelerators is roughly estimated to be 500 tonnes with annual SF6emissions of 35 tonnes. Global banked capacity for medical (radiotherapy) particle accelerators is roughly
estimated to be less than 5 tonnes with annual SF6 emissions of less than 5 tonnes. (Schwarz, 2005).
Figure 8.4

Decision tree for industrial and medical particle accelerators
Start

Are detailed
acquisition and disbursement
data available for thiscategory?

Yes

Use User-Level MassBalance approach.
Box 3: Tier 3

NoAredata on individual
accelerator charges
available?

Yes

Use User-Level EmissionFactor approach.
Box 2: Tier 2

No

Is the Other
Product Manufactureand Use a key category1, and is
this subcategory
significant?

No

Use Country-Level
approach.
Box 1: Tier 1

Yes
Collect data for Tier 3
or Tier 2 method.
Note:
1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for
discussion of key categories and use of decision trees.

Tier 1 method – country-level method
In cases where individual user accelerator charge data is unavailable, one extremely rough method involves
determining the total number of particle accelerators by process description in the country and using factors to2006 IPCC Guidelines for National Greenhouse Gas Inventories

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Volume 3: Industrial Processes and Product Use

determine the country level annual emission rate as noted in Equation 8.18. For this Tier 1 method, the only datathat requires collection is the total number of particle accelerators which contain SF6 by process description in
the given country.
EQUATION 8.18
INDUSTRIAL/MEDICAL ACCELERATOR EMISSIONS (COUNTRY-LEVEL)

Emissions = (Number of particle accelerators that use SF6 by process description in the country) •(SF6 Charge Factor, kg) • (SF6 applicable particle accelerator Emission Factor)
Where:
Number of particle accelerators by type in the country = The total number of particle accelerators by type(industrial high voltage, industrial low voltage and radiotherapy) that use SF6 in the country, 1, 2, etc.
(Only count particle accelerators that use SF6. This differs for the Tier 1 calculation for university
and research particle accelerators)
SF6 Charge Factor = The average SF6 charge in a particle accelerator by process description as noted
below.
SF6 particle accelerator Emission Factor = The average annual SF6 particle accelerator emission rate as afraction of the total charge by process description.

TABLE 8.9
AVERAGE SF6 CHARGE IN A PARTICLE ACCELERATOR BY PROCESS DESCRIPTION
Process Descriptiona

SF6 Charge Factor, kg

Industrial Particle Accelerators – high voltage (0.3-23 MV)

1300

Industrial Particle Accelerators –low voltage (<0.3 MV)

115

Medical (Radiotherapy)

0.5aThis is the average of values ranging from 0.05 kg to over 0.8 kg, depending on model and manufacturer.

Source: Schwarz (2005)

Tier 2 method – user-level emission-factor approach
If data on the quantity of SF6 contained within each industry and medical accelerator are available, use the Tier 2
method for university and research facilities; however, multiply the emission factor for each process description
provided below by the total, country-specific SF6 charge for that process description.
TABLE 8.10
EMISSION FACTOR FOR EACH PROCESS DESCRIPTION,(SF6 EMISSIONS FROM INDUSTRIAL AND MEDICAL PARTICLE ACCELERATORS)
Process Descriptiona

Emission Factor, kg /kg SF6 charge

Industrial Particle Accelerators – high voltage (0.3-23 MV)

0.07

Industrial Particle Accelerators – low voltage (<0.3 MV)

0.013

Medical (Radiotherapy)

2.0aThis emission factor is the average of values ranging from 1 kg to 10 kg per kg charge, depending on model, manufacturer, and service
intervals.

Source: Schwarz (2005)

Tier 3 method – user-level mass-balance method
To calculate SF6 emissions from industrial and medical particle accelerators, use the same Tier 3 method as theuniversity and research facilities. The customer service organisations for manufacturers and distributors of theequipment are likely to have information on equipment stocks, imports, and exports, and on the quantities of SF6
used to fill and refill the equipment.

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Chapter 8: Other Product Manufacture and Use

EMISSIONS FROM OTHER APPLICATIONS OF SF 6 AND PFCs
It is good practice to contact all gas producers/distributors to identify SF6 and PFC users and to investigate thegas consumption of source categories other than those mentioned above. The key difference among theapplications discussed below is the typical delay between the purchase of the SF6 or PFC and the release of thechemical. In some cases (e.g., SF6 used in sound-proof glazing, PFCs used as heat transfer fluids), the chemical
is fairly well contained during the life of the equipment or product, and most emissions are associated with the
manufacture and disposal of the product. In these cases, the delay between the purchase of the chemical and its
final emission depends on the lifetime of the product, ranging from three years for tyres and sport-shoes to 25
years for sound-proof glazing. In other cases (e.g., use of SF6 and PFCs as tracers or in medical applications), thechemical is fully emitted within a year of its purchase. If, as a result of an initial survey, applications with
distinctive delayed emissions appear significant, then good practice is to use a source category-specific emission
calculation, taking into account the delay in emissions.

Adiabatic uses
Adiabatic uses of SF6 and some PFCs exploit the low permeability of these gases through rubber. Historically,SF6 has been the dominant gas in these applications; however, PFCs with similar molecular weights (such as
C3F8) have recently been used as well. Applications with a delay period of 3 years include or car tyres, sportshoe soles and tennis balls (Schwarz et al., 1996). For applications with emissions that are delayed by three years,
the following formula can be used.
EQUATION 8.19
ADIABATIC PROPERTY APPLICATIONSEmissions in year t = Sales in year (t – 3)

Sound-proof glazing
Double-glazed sound-proof windows: Approximately one-third of the total amount of SF6 purchased is released
during assembly (i.e., filling of the double glass window) (Schwarz/Leisewitz, 1999). For the stock of gas
remaining inside the window (capacity), an annual leakage rate of 1 percent is assumed (including glass
breakage). Thus, about 75 percent of initial stock remains at the end of its 25-year lifetime. The application of
SF6 in windows began in 1975, so disposal is only beginning to occur. Emissions from this source sub-category
should be calculated using Equations 8.20 to 8.22:
EQUATION 8.20
DOUBLE-GLAZED WINDOWS: ASSEMBLY

Assembly Emissions in year t = 0.33 • SF6 purchased to fill windows assembled in year t

EQUATION 8.21
DOUBLE-GLAZED WINDOWS: USE

Leakage Emissions in year t = 0.01 • Capacity of Existing Windows in year t

EQUATION 8.22
DOUBLE-GLAZED WINDOWS: DISPOSAL

Disposal Emissions in year t = Amount Left in Window at End of Lifetime in year t • (1 –Recovery Factor)

Unless country-specific data are available, a default recovery factor value of zero should be assumed in Equation
8.22. If no specific information is available for these sub-source categories, good practice is to treat them as
prompt emissions.

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PFCs used as heat transfer fluids in consumer and commercial applications
PFCs are used as heat transfer fluids in a number of high-power-density commercial and consumer electronic
applications. Commercial applications include cooling for supercomputer, telecommunication, and airport radarsystems, as well as drive units (rectifiers) on high-speed trains (Burton, 2006). These applications consume muchsmaller volumes of liquid PFCs than electronics manufacturing, but are believed to be significant among ‘niche’applications. Consumer applications include cooling kits for desktop computers that are operated at high voltages
to increase their processing speed. The specific PFCs used in these applications are believed to be similar to
those identified as heat transfer fluids in electronics manufacturing in Chapter 6. In all of these applications, theliquid PFCs are used in closed modules, indicating that most emissions occur during the manufacture,
maintenance, and disposal of the product or equipment. Thus, if inventory compilers can acquire information onemission rates during the manufacture, maintenance, and disposal of the equipment, along with the quantities ofequipment manufactured, used, and disposed each year, they can use the Tier 2 or Tier 3 method for electricalequipment to estimate emissions. For applications with different emissions profiles (e.g., prompt emissions), theappropriate equation from Section 8.2 may be used.

PFCs used in cosmetic and medical applications
PFCs with relatively large molecular weights (e.g., C10F18) are used in cosmetic and medical applications,
exploiting their ability to carry oxygen to living tissue (May, 2006). Cosmetic applications include anti-wrinkle
creams and are estimated to consume fairly small amounts. Current and potential medical applications include
storage of pancreatic tissue for transplants (using the ‘two-layer method’), eye surgery (to repair retinal tears),pneumonectomy (lung therapy and diagnosis), use as a contrast agent in ultrasonic and MRI examinations, blood
extension, wound healing, and treatment of diseases of the middle ear. All but the first two medical applications
involve only small quantities and/or are at the research stage. Storage of pancreatic tissue is a small but growing
application. Emissions from medical uses are uncertain but are believed to be small.
In all of these applications, the PFC is believed to be emitted into the atmosphere within one year of its purchase.
Thus, emissions from these sources can be estimated using Equation 8.23 for prompt emissions.

Any other uses of SF 6 and PFCs
Other applications for SF6 and PFCs that are not specifically addressed above include their use as tracers (in leakdetection, indoor and outdoor tracking of air-masses, and oil recovery6) and use of SF6 in the production of
optical cables (for fluorodoping of glass fibres 7 ). Often the gases or liquids are emitted within one year ofpurchase. In this case, good practice in calculating SF6 and PFC emissions from these ‘prompt’ emissive
applications is to use the following formula:
EQUATION 8.23
PROMPT EMISSIONS

Emissions in year t = (0.5 • Amount Sold in year t) + (0.5 • Amount Sold in year t – 1)

This equation is similar to the equation for prompt ODS Substitute applications (e.g., aerosols and solvents)
addressed in Chapter 7 of this volume. The equation covers more than one year because both sales and emissions
are assumed to be continuous over the year; that is, chemical sold in the middle of year t-1 is not fully emitted
until the middle of year t.

8.3.2.2

C HOICE OF EMISSION FACTORSFor ‘other’ source categories of SF6 and PFCs that contribute substantially to a country’s SF6 and PFCs
emissions, countries are encouraged to develop country-specific emission factors based on occasional surveys ofrepresentative subsets of sources. It is good practice to clearly document such emission factors. Default emission
factors are provided above for AWACS, accelerators, prompt emissive applications and adiabatic applications,
including windows.

6

D. Vlachogiannis et al. (2005). This paper indicated that some fraction of injected PFCs and SF6 was destroyed during fuelcombustion, but the magnitude of this fraction (compared to the fraction of injected chemical that escaped before
combustion) was unclear.

7

See further information on this application in Schwarz (2005).

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Chapter 8: Other Product Manufacture and Use

8.3.2.3

C HOICE OF ACTIVITY DATA

The activity data for these sub-source categories should be consistent with the data used in the calculation of SF6emissions from other source categories (e.g., electrical equipment) to ensure that the estimate is complete andthere is no double counting. For medical linear accelerators, the customer service organisations for
manufacturers and distributors of the equipment are likely to have information on equipment stocks, imports, andexports, and on the quantities of SF6 used to fill and refill the equipment. Guidance regarding possible sources ofactivity data for other sources is provided under the method for each source category.

8.3.2.4

C OMPLETENESS

Data per application on import, export and consumption from national SF6 and PFC producers and distributors
will suffice, provided that (i) all SF6 and PFC producers and distributors are identified, (ii) domestic consumers
only purchase SF6 and PFCs from national suppliers, and (iii) imports and exports in products (e.g., sport
attributes) are negligible. It is good practice to check regularly for additional distributors to ensure that no gas isimported directly (in bulk) by end-users and that identified products containing SF6 or PFCs are not imported insizeable amounts.
Alternatively, if top-down data on chemical consumption is not available, countries may use information on thenumber of accelerators, AWACS, windows, etc. in use in the country, applying the emission factors that aresupplied in the method for each source category.

8.3.2.5

D EVELOPING A CONSISTENT TIME SERIESFor base year estimates, data may be needed for a few years prior to the base year; one year for prompt
emissions and more years for delayed emission applications. It is good practice to calculate emissions using thesame method for every year in the time series. Where data are unavailable to support a more rigorous method for
all years in the time series, it is good practice to recalculate according to the guidance provided in Volume 1,
Chapter 5.

8.3.3

Uncertainty assessment

If the survey of domestic sales per application by national gas producers and distributors is complete, then theaccuracy of annual apparent consumption data will be high. The uncertainty in emissions estimates will besimilarly small when the uses are all prompt emissions. In case of delayed emission applications, theuncertainties are:•

Default delay times in adiabatic property applications: 3±1 year;•

Defaults for soundproof windows: 50±10% filling emissions and 1±0.5% leakage/breach emissions.

If gas consumption data are not available, uncertainties regarding the numbers and usage of accelerators and
AWACS, etc. become important.
•

For accelerators, the total SF6 charge and leak rate determine emissions and associated uncertainty•

For use of SF6 in AWACS, the number of sorties per plane has a significant impact on emissions anduncertainty.

8.3.4
8.3.4.1

Quality Assurance/Quality Control (QA/QC),
Reporting and Documentation
Q UALITY A SSURANCE /Q UALITY C ONTROL

It is good practice to conduct quality control checks as outlined in Volume 1, Chapter 6, and an expert review ofthe emissions estimates. Additional quality control checks as outlined in Volume 1, and quality assurance
procedures may also be applicable, particularly if higher tier methods are used to determine emissions from this2006 IPCC Guidelines for National Greenhouse Gas Inventories

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Volume 3: Industrial Processes and Product Usesource category. Inventory compilers are encouraged to use higher tier QA/QC for key categories as identified inVolume 1, Chapter 4.
Additional procedures specific to other sources of SF6 are outlined below:

Comparison of emissions estimates using different approaches
Inventory compilers should compare total national potential SF6 and PFC emissions (minus the amount allocatedto the source categories as per chapters 3.10, 4, 6 and 8.2) to the estimated SF6 and PFC emissions from otheruses. These adjusted potential national emissions can be used as an upper bound on emissions.

Activity data check
Inventory compilers should compare the activity data submitted by different producers and distributors, and,adjusting for relative size or capacity of the companies, identify significant outliers. Any outliers should be
investigated to determine if the differences can be explained or if there is an error in the reported activity.

Comparison of emission rates with those of other countries
Inventory compilers should compare the emissions from other SF6 and PFC end-uses included in the national
inventory with information submitted by other similar countries. For each source, emissions per capita or per
unit of GDP should be compared with the corresponding emission rates of other countries. If national figuresappear to be relatively very high or very small, a justification should be provided.

8.3.4.2

R EPORTING AND D OCUMENTATION

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Volume 1, Section 6.11. It is not practical to include all documentation in the national
inventory report. However, the inventory should include summaries of methods used and references to source
data such that the reported emissions estimates are transparent and steps in their calculation may be retraced.
For transparency, it is good practice to report both actual and potential emissions from the source category ‘otheruses’ separately from other SF6 and PFC emissions. In addition, providing information on the specificapplications that are included in this source category is useful for comparing (estimates of) national practices
with other countries, regionally, or globally. In addition, the methods applied and references should be
documented. For delayed emission sub-source categories, annual emissions, delay times and emission factors pertype of sub-source category should be reported.

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Chapter 8: Other Product Manufacture and Use

8.4

N 2 O FROM PRODUCT USES

8.4.1

Introduction

Evaporative emissions of nitrous oxide (N2O) can arise from various types of product use, including:•

Medical applications (anaesthetic use, analgesic use and veterinary use);•

Use as a propellant in aerosol products, primarily in food industry (pressure-packaged whipped cream, etc);•

Oxidising agent and etchant used in semiconductor manufacturing;•

Oxidising agent used, with acetylene, in atomic absorption spectrometry;•

Production of sodium azide, which is used to inflate airbags;•

Fuel oxidant in auto racing; and•Oxidising agent in blowtorches used by jewelers and others.

In general, medical applications and use as a propellant in aerosol products are likely to be larger sources thanothers. It is good practice to estimate and report N2O emissions from these sources. Inventory compilers areencouraged to estimate and report N2O emissions from the other sources as well, if data are available.

MEDICAL APPLICATIONS
Anaesthetic use of N 2 O
N2O for anaesthetic use is supplied in steel cylinders containing a minimum of 98 percent N2O. N2O is usedduring anaesthesia for two reasons: a) as an anaesthetic and analgesic and as b) a carrier gas for volatilefluorinated hydrocarbon anaesthetics such as isoflurane, sevoflurane and desflurane. The anaesthetic effect of
N2O is additive to that of the fluorinated hydrocarbon agents.
Not all anaesthetics require the use of N2O, and the use of N2O is contra-indicated in a small number of medical
situations. The carrier gas during anaesthesia may be either N2O and oxygen or a mixture of air and oxygen, in
which case N2O is avoided.
Inhaled anaesthetic agents are increasingly administered via breathing systems which re-circulate the exhaled
breath of the patient through a canister of carbon dioxide absorbent before directing the gases back to the patient.
Using this method the flow of carrier gas can be reduced considerably after the first few minutes of anaesthesia
when uptake by the patient is high. This technique is known as Low Flow Anaesthesia. Low Flow Anaesthesia
has the advantage of reducing emissions as well as reducing cost.
Some anaesthetics may avoid both N2O and the fluorinated hydrocarbon agents completely by employing atechnique in which an anaesthetic drug is continuously infused into a vein throughout the surgical procedure.
This technique is known as Total Intravenous Anaesthesia.

Analgesic use of N 2 O
Inhaled N2O is used to provide pain relief in certain situations. For example, it is supplied in steel cylinders
containing pre-mixed N2O 50 percent and oxygen 50 percent as premixed nitrous oxide and oxygen mixtures in
the UK. Premixed nitrous oxide and oxygen mixtures are used to provide pain relief in childbirth, and for painfulprocedures of short duration, e.g. for dressings to be changed in burns patients. Premixed nitrous oxide andoxygen mixtures are not used in countries with a very cold climate because the mixture can separate if thecylinders are stored below –6 degrees centigrade, with the consequent risk of administering pure nitrous oxide topatients with no oxygen.

Veterinary use of N 2 O
N2O is also used during animal anaesthesia. Administration methods are similar to those used in humananaesthesia.

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USE AS A PROPELLANT IN AEROSOL PRODUCTS, PRIMARILY IN FOOD
INDUSTRY
N2O is also used as a propellant in aerosol products primarily in food industry. Typical usage is to make whippedcream, where cartridges filled with N2O are used to blow the cream into foam.

8.4.2

Methodological issues

8.4.2.1

C HOICE OF METHOD

It is good practice to estimate N2O emissions from data of quantity of N2O supplied that are obtained frommanufacturers and distributors of N2O products according to Equation 8.24 below. There will be a time delay
between manufacture, delivery and use but this is probably small in the case of medical applications because
hospitals normally receive frequent deliveries to avoid maintaining large stores. Therefore, it is reasonable toassume that the N2O products supplied will be used in one year. In the case of use as a propellant in aerosol
products, there is no reliable data that prove there is a significant time delay between manufacture, delivery anduse. Such being the case, it is considered practical to assume that the N2O products supplied will be used in one
year. Equation 8.24 covers more than one year because both supply and use are assumed to be continuous over
the year; that is, N2O supplied in the middle of year t–1 is not fully used and emitted until the middle of year t.
Different tiers could not be defined for this source category, because there is no other reliable estimation method.
For example, in the case of medical applications, estimations from numbers of anaesthetics given, number ofsurgical beds or hours of anaesthesia could be considered but these methods are likely to be inaccurate. (See
Section 8.4.2.3, Choice of Activity Data.)
EQUATION 8.24
N2O EMISSIONS FROM OTHER PRODUCT USESE N 2O (t ) = ∑ { [0.5 • Ai (t ) + 0.5 • Ai (t − 1) ] • EFi }i

Where:
EN2O(t) = emissions of N2O in year t, tonnes
Ai (t) = total quantity of N2O supplied in year t in application type i, tonnes
Ai (t-1) = total quantity of N2O supplied in year t-1 in application type i, tonnes
EFi = emission factor for application type i, fraction

8.4.2.2

C HOICE OF EMISSION FACTORSMEDICAL APPLICATIONS
It is assumed that none of the administered N2O is chemically changed by the body, and all is returned to theatmosphere. It is reasonable to assume an emission factor of 1.0.

USE AS A PROPELLANT IN AEROSOL PRODUCTS, PRIMARILY IN FOOD
INDUSTRY
For N2O used as a propellant in pressurized and aerosol food products, none of the N2O is reacted during theprocess and all of the N2O is emitted to the atmosphere resulting in an emissions factor of 1.0 for this source.

OTHERSFor the other types of product use, it may not be appropriate to assume an emissions factor of 1.0. In case theinventory compilers estimate and report N2O emissions arising from product use other than medical applications
and use as a propellant in aerosol products, they are encouraged to derive reasonable emission factors for thatsource from literature or measurements.

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Chapter 8: Other Product Manufacture and Use

8.4.2.3

C HOICE OF ACTIVITY DATAMEDICAL APPLICATIONS
Total quantity of N2O supplied by application type should be obtained from manufacturers and distributors of
N2O products. Alternatively, for medical applications, quantity of N2O usage may be obtained from thepharmacy department in individual hospitals that usually have records of the number and capacity of nitrous
oxide cylinders purchased per annum.
The duration of hospital stay following a surgical procedure varies considerably from less than one day toseveral days or weeks. Estimates of the number of anaesthetics administered which are calculated from thesurgical bed occupancy are likely to be inaccurate.
Because N2O is used in only a proportion of anaesthetics its use cannot be estimated reliably from the number ofanaesthetics given.
The flow of N2O (L/min) delivered by the anaesthetic apparatus may be varied by the anaesthetist during thecourse of surgery, typically between zero and 6 L/min. Because of this considerable variability, estimates ofconsumption based on duration of anaesthesia are likely to be inaccurate.
The proportion of anaesthetics in which N2O is used varies between countries and between individualanaesthetists in a given country. Over the recent years there appears to be a general reduction in the proportion ofanaesthetics which incorporate N2O but data are sparse.

USE AS A PROPELLANT IN AEROSOL PRODUCTS, PRIMARILY IN FOOD
INDUSTRY
Total quantity of N2O supplied by application type should be obtained from manufacturers and distributors of
N2O products.

8.4.2.4

C OMPLETENESS

Data per application on import, export and consumption from national N2O manufacturers and distributors will
suffice, provided that (i) all N2O manufacturers and distributors are identified, (ii) domestic consumers only
purchase N2O from national suppliers, and (iii) imports and exports in products (e.g. sport attributes) are
negligible. It is good practice to check regularly for additional distributors to ensure that no N2O is imported
directly (in bulk) by end users and that identified products containing N2O are not imported in sizeable amounts.

8.4.2.5

D EVELOPING A CONSISTENT TIME SERIESIt is good practice to calculate emissions of N2O using the same method for every year in the time series. Where
data are unavailable to support a more rigorous method for all years in the time series, it is good practice torecalculate according to the guidance provided in Volume 1, Chapter 5.

8.4.3
8.4.3.1

Uncertainty assessment
E MISSION FACTOR UNCERTAINTIESIn the published literature it is widely assumed that none of the N2O inhaled by a patient during anaesthesia ismetabolised. N2O is taken up continuously from the lungs as dissolved N2O in blood. The portion which is nottaken up is exhaled in the next breath. Uptake by the patient is high initially and falls progressively in a nearexponential fashion over time. It is reasonable to assume that all the administered N2O is eventually returned tothe atmosphere and the emission factor is 1.0. This is a pragmatic assumption because there are no reliable data.
Any error in the emission factor is likely to be extremely small in comparison with other uncertainties.
Also in the case of use as a propellant in aerosol products, N2O is not likely to be reacted during the process.
Therefore, it is a pragmatic assumption that emission factor is 1.0, and any error in the emission factor is likely
to be extremely small in comparison with other uncertainties.

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Volume 3: Industrial Processes and Product Use

In case the inventory compilers estimate and report N2O emissions arising from product use other than medical
applications and use as a propellant in aerosol products, emission factor uncertainties may need to be carefully
considered.

8.4.3.2

A CTIVITY DATA UNCERTAINTIESThe uncertainties in quantity of N2O supplied by application type obtained from manufacturers and distributorsof N2O products may vary widely from country to country. If the uncertainty estimates are obtainable from the
manufacturers and distributors, those estimates should be used. Otherwise, activity data uncertainties should be
estimated by expert judgement.

8.4.4

Quality Assurance/Quality Control (QA/QC),
Reporting and Documentation

It is good practice to document and archive all information required to produce the national emissions inventory
estimates as outlined in Volume 1, Chapter 6. It is not practical to include all documentation in the national
inventory report. However, the inventory should include summaries of methods used and references to source
data such that the reported emissions estimates are transparent and steps in their calculation may be retraced.
For transparency, providing information on the specific applications that are included in this source category isuseful for comparing (estimates of) national practices with other countries, regionally, or globally. In addition,
the methods applied and references should be documented.
It is good practice to conduct quality control checks and quality assurance procedures as outlined in Volume 1,
Chapter 6. Inventory compilers are encouraged to use higher tier QA/QC for key categories as identified inVolume 1, Chapter 4.
Additional procedures specific to this source category are outlined below:

Activity data check
Inventory compilers should compare the activity data submitted by different manufacturers and distributors of
N2O, and, adjusting for relative size or capacity of the companies, to identify significant outliers. Any outliers
should be investigated to determine if the differences can be explained or if there is an error in the reported
activity.

Comparison of emissions with other countries
Inventory compilers should compare the N2O emissions from types of product use included in the national
inventory with information submitted by other similar countries. For each source, emissions per capita or per
unit of GDP with other countries should be compared. If national figures appear to be relatively very high orvery small, a justification should be provided.

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Chapter 8: Other Product Manufacture and Use

References
SECTIONS 8.1 - 8.3
Aoyama, T. (2004). Japan Electrical Manufacturers’ Association (JEMA), “The Situation of Reduction in SF6
Emissions from Gas-insulated Electrical Equipment In Japan” Paper and presentation delivered to theConference on SF6 and the Environment, Scottsdale, Arizona, December 1-3, 2004.
AREVA (2005). AREVA, World energy experts, Activity and Sustainable Development Report 2004.
(Registered office: rue Le Peletier – 75009 Paris – France, http://www.areva.com/), published in July
2005.
Boeing (2005). “E-3 AWACS in Service Worldwide”, March 2005. Boeing Integrated Defense Systems, P.O.
Box 516, St. Louis, MO 63166, (Available from http://www.boeing.com/defense-space/ic/awacs/docs/E3AWACS_overview.pdf)
Burton, C. S. (2006). “Uses and Air Emissions of Liquid PFC Heat Transfer Fluids from the Electronics Sector,”
Report prepared for Scott C. Bartos, U.S. Environmental Protection Agency.
Ecofys (2005). Reductions of SF6 Emissions from High and Medium Voltage Electrical Equipment in Europe, Final Report
to CAPIEL, S, Wartmann and J. Harnisch, June 28, 2005

FEPC and JEMA (2004). Federation of Electric Power Companies (FEPC) and the Japan Electrical
Manufacturers’ Association (JEMA), “Japanese Emission Factors.” (Personal communication from Mr.
Kiyoshi Saitoh of Japan Electrical Manufacturers Association (JEMA) to Mr. Kiyoto Tanabe, IPCC
Technical Support Unit, November, 2004.)
Harris, D., and Hildebrandt, J. (2003). “Spray Cooling Electrical and Electronic Equipment,” COTS Journal,
November 2003.
CIGRE (2005). International Council on Large Electric Systems (CIGRE) Publication No.276: Guide for the
Preparation of customized “Practical SF6 Handling Instructions”, Task Force B3.02.01, August 2005.
IEC (1996). International Electro-technical Commission (IEC) Standard 60694: “Common specifications forhigh-voltage switchgear and controlgear standards,” Second edition, 1996-05. Geneva, Switzerland.
Koch, E.C. (2004). “Special Materials in Pyrotechnics: III. Application of Lithium and its Compounds in
Energetic Systems;” Propellants, Explosives, Pyrotechnics, Volume 29, Issue 2, Pages 67 - 80, 2004
May, G. (2006). F2 Chemicals Limited. Personal communication with Deborah Ottinger Schaefer, January 23,
2006.
Maruyama, S. and Meguro, M. (2000). “SF6 Gas Emission Reduction From Gas-Insulated Electrical Equipment
in Japan.”, Paper presented at the Conference on SF6 and the Environment: Emission Reduction
Strategies in San Diego, USA (November 2000).
NIST (1997). Gases for Electrical Insulation and Arc Interruption: Possible Present and Future Alternatives toPure SF6; by L. G. Christophorou, J. K. Olthoff, D. S. Green; NIST Technical Note 1425, National
Institute of Standards, November 1997.
Schwarz, W. and Leisewitz, A. (1996). Current and future emissions of fluorinated compounds with global
warming effect in Germany (in German). Report UBA-FB 1060 1074/01, Umweltbundesamt, Berlin.
Schwarz, W. and Leisewitz, A. (1999). Emissions and reduction potentials of HFCs, PFCs, and SF6 in Germany.
Report UBA-FB 298 41 256, Umweltbundesamt, Berlin.
Schwarz, W. (2005). Emissions, Activity Data, and Emission Factors of Fluorinated Greenhouse Gases (F-Gases)in Germany 1995-2002. Research Report 201 41 261/01, UBA-FB 000811/e, Umweltbundesamt, Berlin.
Schwarz, W. (2006). “The German Monitoring System for SF6 Emissions from Equipment for Electricity
Transmission and Distribution.”
Smythe, K. (2004). ‘Trends in SF6 Sales and End-Use Applications: 1961-2003.’ International Conference on
SF6 and the Environment: Emission Reduction Technologies, December 1-3, 2004, Scottsdale, AZ.
U.S. EPA (2004). U.S. Inventory of Greenhouse Gases and Sinks, 1990-2002. U.S. Environmental Protection
Agency, April, 2004.
Vlachogiannis, D., et al. (2005). Assessment of the impact of SF6 and PFCs reservoir tracers on global warming,
the AEOLOS study, Non-CO2 Greenhouse Gases (NCGG-4), coordinated by A. van Amstel, Rotterdam,
p. 389-396.

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Volume 3: Industrial Processes and Product Use

SECTION 8.4
Austria [Umweltbundesamt] (2004), AUSTRIA’S NATIONAL INVENTORY REPORT 2004, Submission
under the United Nations Framework Convention on Climate Change
Beatty PCW, Kay B and Healy TEJ (1984), Measurement of the rates of nitrous oxide uptake and nitrogenexcretion in man. British Journal of Anaesthesia; 56: 223-232.
Environment Canada (2004), Canada’s Greenhouse Gas Inventory 1990-2002
Jordan M. (1996), Pharmacology in the Practice of Anaesthesia p 43. Arold, London. Edited by Kaufman L and
Tabener PV.
U.S. EPA (2004). U.S. Inventory of Greenhouse Gases and Sinks, 1990-2002. U.S. Environmental Protection
Agency, April, 2004.

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Chapter 8: Other Product Manufacture and Use

Annex 8A

Examples of Tier 3 national SF6 inventory
systems

Figures 8A.1 and 8A.2 illustrate the Tier 3 Hybrid approach as it is currently applied in Germany for closed
pressure (high voltage) and sealed-pressure (medium voltage) equipment (Schwarz, 2006). In the diagram, ‘MB’
indicates processes or life cycle stages for which the mass-balance approach is used, while ‘EF’ indicatesprocesses and life cycle stages for which emission factors are used. For example, in manufacturing, the massbalance approach is used to estimate emissions from the filling of gas-insulated switchgear, while emission
factors are used to estimate emissions from the filling of bushings, instrument transformers, and circuit breakers.
In Germany, the latter processes have emission rates of 1 percent or less, making emissions difficult to measureusing mass-balance methods. Note that this diagram is intended to be an example only; when implementing theTier 3 approach, countries are encouraged to choose approaches and emission factors appropriate to theirnational circumstances.

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Figure 8A.1

Example of Tier 3 approach: Germany, High-Voltage equipment

Legend for Emissions Estimation in HV
Mass Balance Approach
SymbolEquation

MB I

Development Emissions = Consumption for Developing minus Return from Development Department

MB II

GIS Charging Emissions = Consumption for Charging minus Charge (nameplate capacities); also applicable to Gas
insulated Lines (GIL’s)

MB III

Operating Emissions I = Annually surveyed topping up by equipment operators

MB IV

Operating Emissions II = Nameplate capacity of decommissioned equipment minus gas recovered from this equipment

Emission Factor (EF) Approach
SymbolKind of Emission Factor (EF)

Multiplied by

EF 1

Factory Filling EF Bushings*

NC** of bushings filled in factory

EF 2

Factory Filling EF Outdoor Instrument Transformers (ITs)

NC of ITs filled in factory

EF 3

Factory Filling EF Gas Circuit Breakers (GCBs)

NC of GCBs filled in factory

EF 4Site Erection EF GIS and GIL

NC of GIS and GIL filled on site

EF 5

Site Erection EF GCBs

NC of GCBs filled on site

EF 6

Site Erection EF Outdoor ITs

NC of Outdoor ITs filled on site

EF 7

Disposal EF

NC of decommissioned equipment* Bushings are treated as integral parts of GIS as of Site erection.
**NC = Total nameplate capacity of equipment undergoing a given process

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Chapter 8: Other Product Manufacture and Use

Figure 8A.2

Example of Tier 3 approach: Germany, Medium-Voltage equipment

Legend for Emissions Estimation in MV
Mass Balance Approach
SymbolEquation

MB I

Development Emissions = Consumption for Developing minus Return from Development Department*

Emission Factor (EF) Approach
SymbolKind of Emission Factor (EF)

Multiplied by

EF 1

Factory Filling EF

NC** filled in factory

EF 2

Site Erection EF

NC*** filled on site

EF 3

Operating EF

NC of operating equipment (total bank from this and previous years)

EF 4

Disposal EF

NC decommissioned* This mass balance approach also applies to manufacturing of Cast Resin Instrument Transformers (ITs).
**NC = Total nameplate capacity of equipment undergoing a given process.
*** In countries where MV equipment is already gas-filled in factories, site erection emissions are negligible.

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