SF6 IN THE ELECTRIC INDUSTRY,STATUS 2000

by P. O’CONNELL, F. HEIL, J. HENRIOT, G. MAUTHE, H. MORRISON, L. NIEMEYER,M. PITTROFF, R. PROBST, J.P. TAILLEBOIS

PAPER PRESENTED IN THE NAME OF WG 23.02

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ABSTRACTA survey is given of the present sit-

uation concerning the environmentalimplications of SF6 used in electricpower equipment. Recently publisheddata on global SF6 production and emis-sion are critically evaluated and extrap-olated to the future. They show that theefforts of the electric industry, namely,original equipment manufacturers(OEM) and users of electric powerequipment (utilities) to reduce SF6 emis-sions are being successfully imple-mented and that a substantial furtheremission reduction can be expected.

It is also shown that the environ-mental impact of SF6 cannot be judgedby its global warming potential (GWP)alone, but that several other factors,which are reviewed in detail, have to betaken into consideration. Recommen-dations are made for providing a basisfor a rational discussion of the issue.

INTRODUCTION

The high global warming potential ofSF6 became known in 1995, as a conse-quence of which the gas was put on thelist of greenhouse gases in the Kyotoprotocol 1997 [1]. The high GWP of SF6triggered various efforts to reduce itsemissions from SF6-insulated transmis-sion and distribution (T&D) equipment.These efforts range from improved seal-ing of equipment over improved gas han-dling procedures, systematic gas reuse

and voluntary emission reduction pro-grams in the electric industry, to gov-ernmental regulatory actions. Key issuesin the ongoing discussion on the envi-ronmental impact of “electric” SF6 arethe quantitative facts of atmospheric SF6emissions, the efficiency of ongoing SF6emission reduction efforts and the roleof the SF6 used in the electric industry ina more general environmental context.This note summarises the presentlyknown facts, tries to extrapolate theminto the future and presents, as conclu-sion, suggestions for supporting a ratio-nal discussion of the SF6 issue.

FACTS AND TRENDSOF ATMOSPHERICSF6 EMISSIONS

Key information for an evaluation ofthe environmental impact of the SF6used in the electrical industry (OEMand utilities) is the global SF6 balance,which is controlled by production, bank-ing of gas in newly installed electricequipment and release into the atmo-sphere by leakage and handling.

The global SF6 production can beinferred from the annual SF6 salesworld-wide, which were compiled bythe major SF6 producers world-widein two surveys [2] [3]. These data do notinclude the SF6 production in Russia andChina and the losses at the SF6 pro-ducers themselves. The production inRussia and China was estimated in [4] to

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Greenhouse effect is areal concern for the future

of our life on earth.Electricity industries areleading players for thecontrol of greenhousegases, mainly through

the generation ofelectricity and the related

CO2 production, lessknown SF6 widely used in

the electricity industry,has a rather strong ‘global

warning potential’ andhas been put in the list ofthe ‘greenhouse gases‘of the Kyoto Protocol.

It is therefore important toknow the most accuratefigures concerning this

gas and its emissions inthe atmosphere, for to-day

and for the mid-term.It is the purpose of the

work carried out bya CIGRE Working

Group 23.02 reportedin the following paper*.

* The paper can be download-ed from the CIGRE web-site.

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be 400 t/y in 1992 and 880 t/y in 1996.For lack of proper data we tentativelyextrapolate these figures to 400 t/ybefore 1995, a linear rise from 1995 to1998 and a constant value after 1998.As the gas producers claim to have SF6release rates 0.5 % to 8 % of theirsales [5], we will account for these byadding an average of 3 % to the sales.The thus corrected total production isrepresented as the uppermost curvein figure 1.

The annual rate at which SF6 isbanked in newly installed electricpower equipment was estimated tobe 2000 t/y in 1995 [4]. This figure isroughly consistent with an estimate ofthe banking rate in GIS, which hasrecently been evaluated by the CIGREWG 23.02. The rate at which electricpower equipment is being installedworld-wide has been approximatelyconstant over the last decade and isexpected to stay constant during the

next decade [6]. The banking in newlyinstalled equipment is assumed toslowly decrease since 1997, becausethe quantity of SF6 required per instal-lation goes down due to improveddesign and other factors. We assumethe banking rate to decrease from2000 t/y in 1996 to 1500 t/y in 2000 andto 1200 t/y in 2010.

Unlike for electric applications, thegas used for non-electric applicationsis usually not recoverable. Most of thisgas is immediately released (e.g. covergas in the magnesium industry, semi-conductor industry, military applica-tions) and a smaller fraction of it isreleased with some delay (e.g. tires,sport shoes, insulation in double-glazedwindows). For simplicity, we approxi-mately assume immediate release ofall “non-electric” SF6. We then obtainthe calculated global atmosphericrelease rate as the difference betweenthe total production rate (upper-

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Figure 1: Elements of global SF6 balance: The total atmospheric release rate (dot-dashedcurve) can be calculated as the difference between the total production rate (uppermost curve)and the estimated rate of banking in newly installed electrical power equipment (lowest curve).This calculated release rate is seen to roughly coincide with the measured atmospheric emis-sion rate (solid curve with error bars).

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most curve in figure 1) and the bankingrate in newly installed electrical powerequipment (lowest broken curve in fig-ure 1). This calculated release rate isrepresented by the dotted curve in fig-ure 1 and can be checked against themeasured atmospheric SF6 emissionrate represented by the curve withattached error bars. This curve is deter-mined from the increase of the SF6 con-centration in the atmosphere, which ismonitored by various atmosphericresearch institutions (e.g. [7]). It is seenthat this measured emission rateroughly coincides with the calculatedrelease rate, which confirms the approx-imate consistency of the assumptionsthat had to be made above.

In their global annual SF6 sales data[2] [3] the major SF6 producers alsodeclare the fractions of the total pro-duction, which were sold to the utilitiesand original equipment manufacturers.These data will be referred to as “sales”

to the electric industry and are shownas the uppermost (broken) curve in fig-ure 2 (data from the RAND study [3]).As the data in [2] and [3] are partly con-tradictory it is important to cross-checkthem with an independent data source,namely, the purchases recorded by theelectric industry (OEM and utilities).Such data have been published forJapan [8], The European Union (EU 15)[9] [10] and the US [11]. As these regionscover the vast majority of “electric” SF6purchases world-wide they can be com-pleted by estimates for the “rest of theworld”. The “bottom-up” data thusobtained will be referred to as “pur-chases” by the electric industry. Theirtotal (OEM + utilities) is represented bythe dot-dashed curve in figure 2. It isseen that the sales data substantiallyoverestimate the purchases till about1998. Possible reasons for this discrep-ancy were discussed in detail in [4].Around 1999 the data become approx-imately consistent.

The purchases by the OEM arepartly banked in newly installed equip-ment and partly lost during testing,manufacturing and commissioning.Note that the banking of gas in newequipment at commissioning is normallyhandled under the responsibility of theOEM. The purchases by the utilitiesessentially cover leakage and handlinglosses during equipment operation andare therefore all released. Subtractingthe gas banked in newly installed elec-tric equipment (see broken curve in fig-ure 1) from the total purchase by theelectric industry one obtains an estimatefor the total release from the electricindustry, represented by the solid curvein figure 2.

From figures 1 and 2 the followingconclusions can be drawn for the pre-sent (1999) situation:

➧ ➧ A substantial fraction of the annualSF6 production is not used in con-tained form (as it is in the electricindustry) but in applications with

Figure 2: Global SF6 balance of the electric industry: Total sales to (uppermost brokencurve) and total purchases by the electric industry (dot-dashed curve). Total release by theelectric industry (solid curve) as difference between purchases and banking rate as shownin figure 1.

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substantial capital investment in han-dling equipment, time for person-nel instruction and world-wide logis-tic efforts.

➧ ➧ In [4] the SF6 banked in electricpower equipment was estimated tohave been about 27 000 t in 1995.With the average annual banking rateassumed in figure 1, the SF6 bankedin equipment in 1999 results about30 000 t. With utility losses of about1500 t/y this yields a world averagerelease rate from operating equip-ment (leakage + handling) of~5%/y. This value is higher than thedata retrieved by CIGRE for high volt-age GIS [12]. These data indicate thatleakage losses from high voltage GISwere in the range 0.5 …1 %/y andhandling losses around 1…2 %/y. Formedium voltage distribution equip-ment of the sealed-for-life type, totallosses during operation are muchlower still. The discrepancy betweenthe CIGRE figures and the worldaverage is most probably due toemissions from regions where SF6technologies and handling

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immediate or eventual release tothe atmosphere.

➧ ➧ There is a clear decreasing trend inthe total SF6 production and in theSF6 release from the electric indus-try since 1996. From 1996 to 1999the electric industry has consider-ably reduced its release with a fur-ther falling trend for the future,although new SF6 equipment con-tinues to be installed.

➧ ➧ It should be noted that thedecrease of “electric” SF6 emis-sions starts already after 1996, i.e.only one year after the high globalwarming potential of SF6 becameknown in 1995. This indicates arapid reaction of the electric indus-try to the problem.

➧ ➧ The continuing downward trend ofthe “electric” SF6 emissions since1996 shows that the electric indus-try has started to implement envi-ronmentally conscious SF6 handlingpractice world-wide. It should benoted that such an implementationis a tedious process, which requires

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practice considerably below thestate of the art are still in use. As anexample of such regional differ-ences, the total “electric” emissionfrom the European Union in 1995was only 3 % of the global emissionwhereas 15 % of the “electric” SF6was banked in this region [13]. Moreprecise and regionally differentiatedstatements will only become pos-sible after more detailed databecome available.

As environmentally conscious SF6handling in the electric industry ispresently still in the process of imple-mentation, it is justified to extrapolatethe “electric” SF6 emissions to thefuture. For this purpose, we make thefollowing assumptions, which are allbased on presently established powerequipment technology and gas han-dling practice and do not yet accountfor future improvements:

➧ ➧ We can estimate an “ideal” lowerlimit based on what would betechnically achievable withoutregarding cost aspects. For this weassume that the utilities reduce theiremissions to a total (leakage +handling) of ~ 1 %/y. Figures in thisrange have already been reported

in the past from some countries(e.g. [14]). The figure of 1 %/y hasalso been proposed in the draft ofthe international electrotechnicalstandard IEC 60517 [15] and hasalready been agreed upon in somevoluntary emission reduction com-mitments (e.g. [5] [8]). Under theassumption of a future annual bank-ing rate as shown in figure 1, thequantity of SF6 banked in electricequipment in 2010 will be approxi-mately 45 000 t. This would resultin future emissions from operatingequipment of approximately 450t/y. The original equipment manu-facturers (OEM) are assumed toreduce their loss rate to less than4 % of the SF6 they install in newequipment. This figure has alreadybeen committed to by an OEMassociation [5]. For medium voltagedistribution equipment of thesealed-for-life type even lowerlosses are already presentlyachieved. With a prospective bank-ing rate of 1200 t/y this would cor-respond to an OEM release ofabout 50 t/y. The ideal lower limitfor emissions from the electricindustry would thus be about500t/y world-wide.

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1 - Promotion of appropriate(state-of-the-art) SF6 hand-ling by international com-mittees:

• • Issuing of recommendations forenvironmentally responsible SF6handling in the electric industry (e.g.CAPIEL/UNIPEDE [16], IEC [17],CIGRE [18-20])

• • Preparation of SF6 handlingguides for the electric industry (IEC[17], CIGRE [19, 20]).

• • Ensuring maximal reuse of SF6 onsite and avoiding unnecessary trans-port (return to the OEM or SF6 pro-ducer) [19] [20] [32].

2 - Activities of OEM (OriginalEquipment Manufacturers):

• • Improved equipment design toreduce the quantity of SF6 requiredper installation and to reduce leak-age.

• • Implementation of appropriateSF6 handling practice in test labo-ratories, factories and on erectionsites.

• • R&D activities to explore the fea-sibility of SF6 substitution (e.g. [21-23])

• • Environmental evaluation of SF6insulated electric power equipmentby environmental lifecycle assess-ment (LCA) [24] according to thestandard ISO 14040 [25].

3 - Activities of electric utilitiesincluding:

• • Improvement of gas handling pro-cedures.

• • Introduction of SF6 inventories.

• • Signing memoranda of under-standing for emission reductionwith a government authority (e.g.USA [26], Japan [5]).

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➧ ➧ For a more realistic scenario wehave to consider cost aspects, dif-ficulties to achieve world-wideimplementation of efficient gas han-dling and remaining equipmentbelow state-of-the-art performance.Under these conditions we assumeutility emissions of about 1000 t/yand OEM losses of approximately200 t/y resulting in total emissionsfrom the electric industry would beabout 1200t/y.

The “ideal” lower limit and the real-istic scenario estimates are representedin figure 2 by the two levels marked“ideal” and “realistic” for the year 2010.They specify the range to which the“electric” SF6 emissions are expec-tedto decrease asymptotically.

With these estimates we come tothe following prospective conclusion:

➧ ➧ The electric industry (OEM + util-ities) has the potential to reduceits SF6 emissions to about 1000t/y world-wide which is a reduc-tion of the 1995 value by morethan 60 % despite of a consider-able increase in gas banked inequipment. This is more than anorder of magnitude better thanthe reduction requirements by theKyoto Protocol.

3. ONGOING SF6EMISSION REDUC-TION EFFORTS

Voluntary programs for the reduc-tion of SF6 emissions from the electricindustry were initiated briefly after thehigh global warming potential (GWP)of SF6 had become known. These activ-ities were organised by the electricindustry (electrotechnical committees,OEM and utilities), SF6 producers andmanufacturers of SF6 handling andrecycling equipment. They consisted of:

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4 - Activities of the SF6 producers:

• • Establishment and updating ofglobal SF6 production inventories[2] [3]

• • Offering take-back services forused SF6

5 - Manufacturers of SF6 hand-ling and recycling equipment:

• • Performance improvement andcost reduction of SF6 handling andrecycling equipment

• • Support of personnel ins-truction.

4. SF6 IN A GENERALENVIRONMENTALCONTEXT

Although SF6 is one of thestrongest greenhouse gases by itsmolecular properties, it is important toput it into a general environmental con-text and to do this in a quantitative way.In this respect, the following aspectsare of particular importance for electricpower equipment:

SF6 is one of many other man-madegreenhouse gases and is emitted incomparatively small quantity. Its con-tribution to global warming can beapproximately assessed in terms ofCO2 - equivalent emission rates. A CO2

- equivalent emission rate is the actualemission rate multiplied by the globalwarming potential (GWP) of the gas. Atpresent (1999), the SF6 emission fromthe electric industry is about 2200 t/y(see figure 2) which, with a GWP of 22500 for SF6 [33], corresponds to 50Mt/yCO2 equivalent. The total equivalentemission of the other man-made green-house gases is presently 43 000 Mt /yCO2 equivalent [6]. The present shareof “electric” SF6 in man-made green-house gas emissions is therefore:

50 Mt/y (CO2 equivalent) /43 000 Mt/y ~ 1.16 10-3 ~ .1 % (1999)

As estimated above, the full imple-mentation of appropriate SF6 handlingin the electric industry will reduce the“electric” SF6 emissions to about 1000t/y corresponding to ~ 23 Mt/y CO2

equivalent. Considering that the globalemission rate of all man-made green-house gases will have increased toapproximately 50 000 Mt/y CO2 equiv-alent in 2010 [6], the share of the elec-tric SF6 emission in relation to the totalgreenhouse gas emissions will then be

23 Mt/y (CO2 equivalent) /50 000 Mt ~ 0.04 % (2010)

It can thus be concluded that the“electric” SF6 emissions, which arealready now quantitatively insi-gnificant, will become irrelevant inthe future despite the ongoinginstallation of SF6 insulated powerequipment. This conclusion mayseem against intuitive expectation,which considers only the molecularproperty GWP and does not accountfor the quantitative emission SF6data.

It has to be noted that the aboveestimates do not yet account for thepositive environmental value of SF6when it is viewed in the context ofan integral environmental evalua-tion. Because of its high functionalefficiency SF6 allows to design verycompact equipment. This allows thesaving of materials and energy losses,both of which substantially contributeto the integral environmental impact.These savings have to be balancedagainst the negative impact of the SF6losses. The procedure for such a bal-ance is LCA (environmental life-cycle assessment) according to theinternational standard ISO 14040 [25].LCA evaluates the integral environ-mental impact of a technology andallows, in particular, the assessmentof the relative contribution of SF6.Applying LCA to a regional electricpower supply system [24] has led tothe result that the use of SF6-insula-tion reduces the environmental impact

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of the overall system. Material sav-ings, lower energy losses and otherfeatures enabled specifically by SF6over-compensate for the negativeimpact of the SF6 emissions. It hastherefore to be concluded that SF6,in spite of its high GWP, may evenreduce the integral environmentalimpact of electric power equip-ment due to its extraordinaryfunctional performance.

In contrast to many other green-house gases, the SF6 used in electricpower equipment is, by its very func-tion, enclosed and is practically alwayshandled by expert personnel. In con-trast to consumer products, it is there-fore relatively easy to implement con-servative gas handling, once thenecessary investments in gas handlingequipment and personnel instructionhave been made. The electric industryhas proven that it has started toimplement appropriate SF6 handlingworld-wide.

Several decades of intense andcomprehensive research have shownthat a functionally equivalent substi-tute gas for SF6 does not exist forphysical reasons (e.g. [21]). As a conse-quence, SF6 substitution, if enforced,would become technically difficult, eco-nomically unacceptable and environ-mentally disadvantageous, particularlyfor high voltage transmission equip-ment. Nevertheless,the OEMs are con-tinuing research and development workto identify performance niches (mainlylower voltages and currents) in whichSF6-free equipment might eventuallybecome feasible. The 1997 Kyoto pro-tocol for the reduction of greenhousegas emissions [1] explicitly lists SF6 asthe gas with the highest global warm-ing potential. This obliges all partici-pating countries to achieve SF6 emis-sion reduction. The methods by whichgovernmental institutions try to achievethis goal and the reduction levels theyhave as targets are at the choice of the

countries. Presently, three major con-cepts of governmental action can berecognised:

a) Establishment of national SF6inventories (e.g. in Brazil [14], EU [27],D [28] [29], Japan [5]).

b) Voluntary agreements on SF6emission reduction between govern-ment and electric industry (e.g. in US[26], Japan [5], D [30]).

c) Straightforward taxation of SF6as greenhouse gas and/or programmedphase-out (e.g. DK [31]). Whereas theestablishment of national SF6 invento-ries is necessary and voluntary emissionreduction agreements have alreadyproven to be efficient, straightforwardtaxation and/or phase-out call forremarks:

• • Such measures are solely basedon a material specific property (theglobal warming potential) and dis-regard functional aspects, the roleof the gas in the context of an inte-gral environmental impact assess-ment (LCA) and the economic con-sequences.

• • Such measures will have several(probably unintended) counter-productive consequences.

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They will cause a cost increase formaintaining and retrofitting existingSF6 power equipment. They willenforce technologies with increas-ed cost and (integral) environmen-tal impact. They may even make itimpossible to provide certain vitalfunctions in the T&D system, whichcan not be realised technically with-out SF6, without reverting to his-torical technologies which werephased out decades ago, not onlyfor economic but also for safety andenvironmental reasons.

5. RECOMMEN-DATIONS

Based on the facts and figures pre-sented in this paper it is recommendedthat:

(1) Information of the kind presentedin this document is made available onthe CIGRE SF6 web-site and regularlyupdated, with free access for CIGREmembers and non-members.

(2) CIGRE includes instructions onthe establishment of SF6 inventoriesin the planned practical SF6 handlingguide presently in preparation. Theseinstructions could be based on theCAPIEL Inventory Methodology whichis based on the Tier 3b Mass BalanceMethodology according to IPCC GoodPractice [10].

(3) CIGRE develops a sample formfor a voluntary SF6 emission reductionagreement between government andelectric industry. This form could bebased on existing documents of thistype (e.g. US [26], Japan [5], D [30]).

(4) Background information of thekind presented in this document ismade available to governmental insti-tutions and their consultants and to allrelevant international and national orga-nizations in order to provide informa-tion on the quantitative aspects of SF6use in the electric industry. This isexpected to help putting the ongoingSF6 discussion on a rational basis.

6. REFERENCES

[1] Kyoto Protocol: http://www.unfccc.de/resource/convkp.html[2] Sales of Sulphur Hexafluoride (SF6)by End-use Applications, Science andPolicy Services Inc., Washington DC,1997[3] Katie D. Smythe, RAND Environ-mental Science & Policy Center Pro-duction and Distribution of SF6 by End-Use Application, EPA Conference onSF6 and Environment, San Diego,November 2000 http://www.epa.gov/highgwp1/sf6/agenda.html[4] M. Maiss and A. M. Brenninkmaijer,«Atmospheric SF6, trends, sources andprospects», Envir. Science & Technol.,Oct. 1998[5] Shigeru Maruyama, The Federationof Electric Power Companies (FEPC),Japan: ”SF6 emission reduction formgas insulated electrical equipment inJapan”, Presentation at the CIGRE GISworkshop April 19th 2001, Hakone Japan[6] International Energy Agency:http://www.iea.org/weo/electricity.jpgand http://www.iea.org/pubs/review/files/ ire99/04-ire.htm[7] M. Maiss and C.A. Brenninkmeijer:“A reversed trend in emission of SF6into the atmosphere?” 2nd Int. Symp.on Non-CO2 Greenhouse Gases(NCGG-2), Noordwij-kerhout, TheNetherlands, 8-10 September 1999, vanHam et. al. eds., Kluwer Academic Pub-lishers, Dordrecht[8] Federation of Electric Power Com-panies Japan; Japan Electrical manu-facturers’ Association; Asahi Glass Co.Ltd.; Kanto Denka Kogyo Co. Ltd.:«Partnership Activities for SF6 GasEmission Reduction from Gas InsulatedElectrical Equipment in Japan.»IPCC/TEAP Joint Expert Meeting, Pet-ten, The Netherlands, 26-28 May 1999[9] «Special Report on behalf of theEuropean Commission, DG Environ-ment for Economic Evaluation of Emis-sion Reductions of HFCs, PFCs andSF6, Final report», April 25, 2000

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[10] ECCP, Brussels, issued by Ecofys andEnviros: «Final Report of the EuropeanClimate Change Programme, WG Indus-try, Fluorinated Gases» June 18, 2001[11] US EPA: «Inventory of U.S. Green-house Gas Emissions and Sinks: 1990-1998.» April 15, 2000[12] CIGRE Brochure 150: Report on thesecond international survey on highvoltage gas insulated substations (GIS)service experience[13] J.W. Wouda (CAPIEL/EURELEC-TRIC): “SF6 management and handlingby switchgear manufacturers and users:an overview of the situation in the Euro-pean Union” See notes under ref [13 ]http://www.epa.gov/highgwp1/sf6/pdf/woudap.pdf[14] M. J. Pereira et al., SF6 leakagessurvey in Brazilian Gas Insulated Sub-stations, CIGRE 1996, 23-103[15] IEC Standard 60 5170.[16] CAPIEL/UNIPEDE: Joint statementon switchgear and the greenhouseeffect, March 1997[17] IEC Standard 1634 “Use and han-dling of SF6 in HV switchgear andcontrolgear”[18] CIGRE WG 23.10, “ SF6 and theglobal atmosphere”, ELECTRA 164(1996), 121-138[19] CIGRE WG 23.10, “ SF6 RecyclingGuide”, ELECTRA 173 (1997), 43-69[20] CIGRE WG 23-10, “ Guide for SF6gas mixtures”, CIGRE TechnicalBrochure 163, August 2000[21] L. Niemeyer: A systematic searchfor insulation gases and their environ-mental evaluation, Gaseous DielectricsVIII, Plenum, New York, 1998[22] L. Christophorou et al.:”recentadvances in gaseous dielectrics at OakRidge National Laboratory”, IEEE Trans.Electr. Insul.,19 (6), 1984, p. 550-566[23] S.Yanabu: “New concept of switch-gear for replacing SF6 gas or SF6 mix-ture”, IXth Internat. Sympos. onGaseous Dielectrics, Turf Valley, Mary-land, May 2001 [24] LCA-study «Electricity supply usingSF6 technology», April 1999, projectgroup ABB, PreussenElektra, RWE,

Siemens, Solvay. Summary in: B. Zahnand E. Ruess, “Economical and eco-logical system comparison for the elec-tricity supply of an urban area”, CIGRESC23.99 (COLL) IWD, Zurich 1999,short version under http://www.solvay.com/fluor/en/news/julioekobilanz.html[25] Environmental lifecycle assess-ment: Standard ISO 14040 http://www.ansi.org/public/iso14000/docs/14040.html[26] US Environmental ProtectionAgency (EPA): SF6 emission reductionpartnership, memorandum of under-standing, December 2000, http://www.epa.gov/highgwp1/sf6/[27] Ecofys and Enviros: «Final Reportof the European Climate Change Pro-gramme, WG Industry, FluorinatedGases» June 18, 2001[28] K. Schwab, Perspectives on SF6emission reduction in Germany, EPAconference on SF6, San Diego, Nov.2000, http://www.epa.gov/highgwp1/sf6/pdf/schwaabp.pdf[29] W. Schwarz et al: “ Emissions andreduction potentials of HFC, PFC andSF6 in Germany, October 1999, seehttp://www.epa.gov/highgwp1/sf6/agenda.html[30] Association of German ElectricPower Utilities – VDEW, Confederationof the German Electrical Engineeringand Electronics Industries: Declarationon the Use of SF6 in Connection withElectrical Switchgear and Substationsin Germany, 1998[31] F. Jensen: Danish plan for regulat-ing the industrial greenhouse gases,EPA Conference on SF6, San Diego,Nov. 2000, http://www.epa.gov/hgwp1/sf6/pdf/[32] Standard IEC 60480, presentlyunder revision[33] F. Moore et al.: “Measured SF6losses and its influence on age of air cal-culations”, Proc. 9th Int. Symp. onGaseous Dielectrics, Ellicot City ML,USA, May 2001. This paper contains therecently revised global warming char-acteristics of SF6: atmospheric lifetime:520 years and GWP: 22 500 ■