Source category fugitive emissions from 1B2b – Natural gas

3.3.4.1 Source category description for 1B2b

Emissions from natural gas production (1B2b ii) are only occurring for the years of operation of the single production plant in Switzerland from 1985–1994. Other emissions in this sector occur from natural gas transmission (1B2b iv) and distribution (1B2b v). Emissions from transmission include leakages from gas pipelines, small-scale damages, revision processes of the pipeline network and leakage of network components. Emissions from accidents in the gas pipeline system are reported under source category (1B2b vi).

Table 3-95 Specification of source category fugitive emissions from 1B2b Natural gas in Switzerland.

3.3.4.2 Methodological issues for 1B2b Methodology (1B2b)

According to the decision tree for natural gas systems, Switzerland follows a Tier 2 approach for emissions attributed to 1B2b iv Transmission and storage as well as 1B2b v and a Tier 1

1B2 Source Specification

1B2b Fugitive emissions attributed to natural gas

Emissions from gas network

3 Energy: 3.3 Source category 1B – Fugitive emissions from fuels

approach for emissions concerning 1B2b ii Production in order to estimate fugitive emissions under 1B2b fugitive emissions from natural gas (IPCC 2006, Volume 2 Energy, chp. 4

Fugitive Emissions, Figure 4.2.1). For emission calculations country-specific emission factors (partly) as well as activity data are available for source category 1B2b. Emissions from source category 1B2 are key, however, the contribution from 1B2b ii is small and therefore the use of a Tier 1 method for this source category is justified.

For source category 1B2b ii, emissions are calculated based on annual production data and default emission factors (IPCC Tier 1 approach). Production data under 1B2b ii are only available for the years 1990–1994 because the single production site was closed in 1994.

Emissions from gas transmission and distribution are calculated with a country-specific method, based on length, type and pressure of the gas pipelines, supplemented by estimates of fugitive emissions from distribution network components (regulators, shut off fittings and gas meters). Losses from end-users’ appliances (household or industry) are reported in the corresponding source category in sector 1A.

Emission factors (1B2b)

CO2, CH4 and NMVOC default emission factors for natural gas production are taken from the 2006 IPCC Guidelines (IPCC 2006) as documented in the internal emission database

documentation (EMIS 2015/1B2b Gasproduktion).

Emission factors for gas transport and distribution losses (source 1B2b iv and 1B2b v) have been reassessed in a recent study by Quantis (2014). Due to insufficient data regarding distribution network components (regulators, shut-off fittings and gas meters) and

appropriate emission factors, emissions are estimated as a fixed percentage of the network losses.

Table 3-96 Emission factors for fugitive emissions of source category 1B2b Natural gas in 2014.

Emission factors for gas distribution losses due to accidents in the gas pipeline system are also based on the same study by Quantis (2014) and reported under 1B2b vi Other leakage.

Table 3-97 Emission factors for 1B2b vi Other leakage in 2014.

Source/fuel CO2 CH4 N2O NOx NMVOC SO2 CO

g/GJ g/GJ g/GJ g/GJ g/GJ g/GJ g/GJ

1B2b Natural gas

Production NO NO NO NO NO NO NO

Transmission 312 17'888 NA NA 1'427 NA NA

Distribution 312 17'888 NA NA 1'427 NA NA

Source/fuel CO2 CH4 N2O NOx NMVOC SO2 CO

g/GJ g/GJ g/GJ g/GJ g/GJ g/GJ g/GJ

1B2b vi Other Leakage 312 17'888 NA NA 1'427 NA NA

3 Energy: 3.3 Source category 1B – Fugitive emissions from fuels

Activity data (1B2b)

Activity data for fugitive emissions from gas production (1B2b ii) are the actual gas pro-duction data for the years 1990–1994 (SFOE 2015). For gas transmission (1B2b iv), distribution (1B2v), and other (1B2b vi), activity data shown in Table 3-98 and Table 3-99 represent the actual amount of gas lost.

For source categories 1B2b iv and 1B2b v, information regarding the gas transport and distribution network from the Swiss Gas and Water Industry Association (SGWA 2015) is used as activity data (see Quantis 2014).

Fugitive emissions from pipelines are the major emission source in source category 1B2b.

Fugitive emissions from damages and ruptures of the pipelines, maintenance of the pipelines and the components are very small (Quantis 2014). Total CH4 emissions from gas trans-mission and distribution decreased due to gradual replacement of cast-iron pipes with polyethylene pipes.

Table 3-98 Activity data for fugitive emissions from 1B2b

Concerning isolated events in source category Other (1B2b vi), there were two accidents reported by the transit pipeline operator, one in 2010 and 2011. These events have also been taken into account in the recent reassessment of fugitive emissions from the gas industry (Quantis 2014).

Table 3-99 Activity data for 1B2b Other leakage.

3.3.4.3 Uncertainties and time-series consistency for 1B2b

According to the assessment by Quantis (2014), an uncertainty of 30% is estimated for fugitive CH4 emissions from natural gas pipelines in Switzerland.

A preliminary uncertainty assessment of all other sources in source category 1B2 based on expert judgement results in medium confidence in the emissions estimate (see Table 1-11).

Consistency: Time series for 1B2b Natural gas are all considered consistent.

1B2b Natural Gas / 1B2d Other Unit 1990 1995 2000

1B2b Natural gas GJ 832'181 832'934 671'875

Production GJ 130'000 NO NO

Transmission GJ 26'135 29'189 30'923

Distribution GJ 676'046 803'745 640'952

1B2b Natural Gas / 1B2d Other Unit 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

1B2b Natural Gas 535'013 515'652 511'645 497'610 485'484 472'966 465'376 461'196 425'593 425'593

Production GJ NO NO NO NO NO NO NO NO NO NO

Transmission GJ 31'813 31'902 32'786 32'864 32'887 32'699 32'678 32'682 33'309 33'309

Distribution GJ 503'200 483'750 478'859 464'746 452'597 440'267 432'698 428'514 392'284 392'284

1B2b Natural Gas / 1B2d Other Unit 1990 1995 2000

1B2b vi Other Leakage GJ NO NO NO

1B2b Natural Gas / 1B2d Other Unit 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

1B2b vi Other Leakage GJ NO NO NO NO NO 35'225 27'940 NO NO NO

3 Energy: 3.3 Source category 1B – Fugitive emissions from fuels

3.3.4.4 Category-specific QA/QC and verification for 1B2b The general QA/QC measures are described in section 1.2.3.

As suggested by the 2006 IPCC guidelines (IPCC 2006) the gas industry was involved in the reassessment of fugitive emissions from the natural gas system (Quantis 2014).

3.3.4.5 Category-specific recalculations for 1B2b Recalculations reported in submission 2015

 No category-specific recalculations were carried out.

Recalculations reported in submission 2016

 No category-specific recalculations were carried out.

3.3.4.6 Category-specific planned improvements for 1B2b No category-specific improvements are planned.