Conceptualising energy security andmaking explicititspolysemicnature$LynneChesternTheJohnCurtinInstituteofPublicPolicy,CurtinUniversity,GPOBoxU1987, PerthWA6845,Australiaarticle infoArticlehistory:Received15July 2009Accepted 19October 2009Available online11November 2009Keywords:EnergyregimeEnergy securitySecurity ofsupplyabstractTwenty-rstcenturyaccesstoenergysourcesdependsonacomplexsystemofglobal markets, vastcross-border infrastructure networks, a small group of primary energy suppliers, and interdependencieswith nancial markets and technology. This is the context in which energy security has risen high on thepolicy agenda of governments around the world and the term energy security has quietly slipped intothe energy lexicon. The limited discourse about the nature of the term or its underlying assumptions hasbeen totally eclipsed by an almost overwhelming focus on securing supplies of primary energy sourcesandgeopolitics. Anexaminationof explicitandinferreddenitionsndsthattheconceptof energysecurity is inherently slippery because it is polysemic in nature, capable of holding multiple dimensionsandtakingondifferent specicitiesdependingonthecountry(or continent), timeframeor energysource to which it is applied. This slipperiness poses analytical, prediction and policy difculties but ifexplicitlyrecognisedthroughdenitional clarity, newlevelsof understandingwill enrichthepolicydebate todealwithobstaclesimpacting ontheconstantly evolvingnature ofenergysecurity.&2009ElsevierLtd.Allrightsreserved.1. IntroductionThe termenergy security is ubiquitous to contemporarydiscussionaboutenergyissuesandclimatechange. Thetermiscommonly found embedded in discussion framed around ahandful of notions which denote unimpeded access or no plannedinterruptions to sources of energy, not relying on a limitednumber of energy sources, not being tied to a particulargeographic region for energy sources, abundant energy resources,anenergysupplywhichcanwithstandexternal shocks, and/orsomeform of energy self-sufciency.The terms blithe appearance throughout a wide range ofreports and documents issued over the last decade or soby government and supranational organisations (such as theEuropeanCommission), andacademicdiscourse, hasbeenrarelyaccompaniedbydiscussionorexplanationofthenotionswhichunderpin its meaning. Of the limited discussion that has ensued, ithas been more peripheral than centre stage and often the meaningattributed has been more implicit than explicitly stated. The termhas quietly slipped into the energy lexicon and assumed arelatively prominent position. The limited discourse about itsnature or any underlying assumptions has been totally eclipsed byan almost overwhelming focus in the literature on securingsupplies ofprimary energy sourcesandgeopolitics.This has ledtosporadic references about the termenergysecuritybeingabstract, elusive, vague, inherentlydifcult andblurred (For example: Alhajji, 2006; Isbell, 2007; L oschel,Mosleneret al., 2009; Wright, 2005). Tworecent contributionshavegonesomewaytodevelopadeeperunderstandingof theterm but notably the comments of both have been eclipsed by thecontext of wider energy-related discussions (Chevalier, 2006;Kruyt, vanVuuren et al., 2009).This article is intended as a contribution to redressing this gapintheliteratureabouttheconceptualisationof energysecurity.Thearticleis structuredinsixsections. Thefollowingsectionconsiders the worlds energy regime in which the terms usage hasevolved in the period since the Second World War. A third sectionconsiders denitions of energy security, explicit and inferred,increasingly apparentinrecentdecadesfrom whichanumber ofaspects about the term are discerned and subsequently discussedbeforeconsideringthemarket paradigms underpinningenergysecuritydenitions, andtheimplicationsforthepolicyroleandactionsofgovernment. Aconcludingsectiondrawstogetherthesalient pointsandpositssomeimplicationsshoulddenitionalclarity remain the exceptionrather thantherule.2. The energy regime post World War 2Usage of the termenergy security has evolved with thetransformation of the worlds energy regime. This transformationis marked by, inter alia, the growing dominance of non-renewablefossil fuels, the liberalisation of energy markets, the developmentARTICLEINPRESSContentslistsavailableatScienceDirectjournal homepage: www.elsevier.com/locate/enpolEnergyPolicy0301-4215/$ - seefront matter&2009ElsevierLtd.All rightsreserved.doi:10.1016/j.enpol.2009.10.039$An earlier version of this paper formed part of a presentation to the November20082ndIAEEAsianConferenceheldinPerth,Australia.nTel.: +61 8 9266 1707;fax: +61 8 9266 3658.E-mailaddress: I.chester@curtin.edu.auEnergyPolicy 38(2010) 887895ARTICLEINPRESSofnuclearenergy, theescalatingenergydemandsofdevelopingnations, andtheimpactsof political instabilityandlarge-scalenaturalevents.2.1. IncreasingrelianceonoilManycountries, particularlythosecomprisingtheOrganisa-tion for Economic Co-operation and Development (OECD), becamestronglyreliantonMiddleEastoilasanenergy sourcefollowingthe Second World War. This fossil fuel was integral to the worldspost-war economic growth trajectory particularly through thetransportsectorandcurrentlyaccountsfor34%ofworldenergyuse (IEA, 2008a). Oil was relatively abundant and cheap until theoilpriceshocksofthe1970sprecipitatedbytheOrganisationofPetroleumExporting Countries restriction onproduction. Theshortfall inglobal energysupplies ledtotheformationof theInternational Energy Agency (IEA) with member countriesrequired to hold oil stocks for sharing in an oil supply emergency.Italsoledtoaviewofenergysecurityassynonymouswiththeneed to reduce dependence on oil consumption (Martin andHarrje, 2005; UNDP,2000).2.2. The1970seconomiccrisisandtheliberalisationof energymarketsThe rapidly accelerating oil prices of the 1970s occurred duringa period of rampant ination, persistently high levels ofunemployment, growinggovernmentexpendituresaccompaniedby comparativelydecliningrevenues, asharpdownturninprotrates, falling productivity, and a strong trend towards theinternationalisationofproduction(Castells, 1989;Dunford, 1990,2000; Moseley, 1988). This was a period of unprecedentedeconomic phenomena and accepted economic managementstrategies did not restore the growth path of the 1950s and1960s leadingtostrident criticismof government interventionandregulation.By the 1980s the need for greater competition and lessgovernment involvement was strongly advocated for networksectors (especially electricity, gas and telecommunications) whichhadbeentraditionally dominatedbygovernment monopolies.Considerablerestructuringof energymarketsaroundtheworldhas subsequently occurred and, in electricitys case at anastonishing pace (Chester, 2007: pp. 1626). Competition hasbeeninjectedthroughthe breaking-upof verticallyintegratedmonopolies, newforms of pricing and access regulation ofmonopolynetworks, andthecreationof newtradingmarkets.This restructuring has not only been promoted by individualcountrygovernmentsbutactivelyencouragedbytheOECD, theWorldBank, theInternational MonetaryFund, andinternationaltrading agreements such as the General Agreement on Tariffs andTrade and the subsequent General Agreement on Trade inServices.2.3. Nuclear energyTheimmediatedecadesfollowingtheSecondWorldWaralsosaw the rapid development of nuclear energys use for electricitygeneration. Twenty-ve countries by the late 1970s, including theUnitedStates, UnitedKingdom,France, Germany andRussia, hadembarkedonnuclear-basedelectricity generation.Two accidentsin1979and1986(ThreeMileIslandintheUnitedStates andChernobyl inthe former Soviet Union) signicantlyweakenedpublic acceptability for this energy source. Very high capital costsconsistentlyexceedingbudget, constructiontimesincreasingtooveradecade, decommissioningandradioactivewastedisposaltaking many times the plant life, reactor safety and concern aboutitspotential applicationforweaponspurposeshaveall contrib-utedtoasignicantslowinginnuclearenergysgrowth(Green-peace International, 2007; Thomas, 2008). By 2006, nuclearenergy accounted for around 15% of the worlds electricitygenerationcomparedto41%fromcoal andafurther 20%fromgas(NuclearEnergyAgency, 2003). Thecurrent climatechangedebatehas seensomeresurgenceinthepromotionof nuclearenergyas alow-emitter of greenhousegases relative tootherprimary fuels for electricity generation.2.4. FluctuatingfortunesforcoalandnaturalgasTheemergenceofnuclearenergyfurtherreducedtheroleofcoal. Oil hadbecomethemainfuel for transport by1930andreplacedcoal asindustrysprimaryenergysourcefromthelate1950s as prices fell with the development of pipeline andsupertanker infrastructure(McNeill,2001).Similarinfrastructuredevelopment for natural gas led to lower prices and the expansionofthisparticularprimary energysourcewhichnow accountsforalmost a quarter of the worlds energy consumption. Theconsumptionof natural gas has doubledsince 1980 as infra-structure to overcome its transportation became increasinglyavailable. Theworldsknownnaturalgasreservesareaslargeasoil but shippingconstraintshindereddevelopment. Thesehavebeenremovedwiththelatetwentiethcenturyemergenceof aglobal market for liqueed natural gas (LNG). Development of LNGhasmeantthewideravailabilityof thisenergysourcealthoughnaturalgasresourcesareconcentratedinahandfulofcountries.TheformerSovietUnionandtheMiddleEastholdnearly75%ofknown world reserves (IEA,2008b;Yergin,2005).2.5. Theenergy appetiteoflargedevelopingcountriesThelatetwentiethcenturyalsowitnessedtheemergenceofChina and India as key energy consumers and major energyimporters. In 1980 these two countries accounted for less than 8%ofthe worldsenergy consumption.By2005theirshare was18%anditisprojectedthat, overthenext25years, theircombinedenergy use will more than double to reach 25% of worldconsumption(IEA,2008a;2008b).Swift growthinChinascoal consumptionoverthepastfewyears has seen a sharp increase in coals share of world energy use.Thecostofcoal isnowcomparativelylowasglobal oil andgasprices have, in recent years, escalated and remain high, comparedto their levels inthe1990s(IEA,2008b;UNDP,2004).2.6. Political instability andextremenaturaleventsGiven the levels of energy import dependence around theworld, the possibility of serious energy supply interruptionshas been heightened with political instability in suppliercountries and the increasing frequency of disruption to gassuppliesfromRussiatoEurope.Risksto theenergysupply chaininfrastructurehavealsocometotheforewiththe11September2001terroristattacksintheUnitedStates, andextremenaturaleventssuchasHurricaneKatrinain2005andthe2009oodsand bushres in north-eastern and south-eastern Australia,respectively.A rapid escalation in oil prices, the disruption of gas supplies toEurope during freezing winter temperatures, electricity blackoutsfollowinghurricanes or other severe naturaldisasters, alltend tofocus public and media attention on energy supply issues and themeasures initiated by governments to overcome short-termsupplydisruptions. This alsowas thefocus of energysecurityL.Chester/EnergyPolicy38(2010)887895 888ARTICLEINPRESSstrategiesfollowingtheoildisruptionsofthe1970s. Buttodaysenergy supply systemsarefarmorecomplexthanafew decadesago and it is this complexity which has attributed far more to thetermenergysecurity thandependencyonaparticularprimaryenergy source.2.7. Theenergyregimeofthetwentieth-rstcenturyTwentieth-rstcenturyaccesstoenergysourcesdependsonopen global markets and a vast infrastructure network of offshoreplatforms, pipelines, tankers, reneries, storage, generationcapacity, and transmission and distribution systems. Cross-borderpipelines and strategic transport channels feature strongly, Chinaand India are major energy importers, there is a growing relianceon an ever-smaller group of oil and gas suppliers as theinterdependence between industrialised countries and energyexporters has deepened, nancial markets and energy markets areclosely linked, and technology has created interdependenciesbetween electricity and oil rening as well as natural gasprocessing. This complexity brings heightened risks of majorsupply disruption through political conict or war, technicalsystemfailures, accidents, sabotage, extreme weather eventsor nancial market turmoil (Birol, 2006; UNDP, 2004; Yergin,2005).Vast networks of complex energy supply systems fromupstream to downstream, energy markets as exemplars ofliberalisation, thedominationbyfossilfuelsofagrowingglobalenergy dependence, the incapacity of most countries to be energyself-sufcient, around 80% of greenhouse gas emissions generatedbytotalworldenergyconsumption whichisprojectedtoriseby50%inthe25yearperiodto2030without fundamental policychanges or major supply constraints (IEA, 2008b), and globalattention focused on addressing the environmental consequencesof uncheckeduseof fossil fuels. Thisisthepolitical, economicandsocial context inwhichusageof thetermenergysecurityhasevolved. Itisalsothecontextinwhichenergysecurityhasbeenplacedhighonthe policyagenda of the developedanddeveloping world, and supranational organisations such asthe European Commission (EC), the World Economic Forum,the OECD, the NorthAtlantic TreatyOrganisation(NATO), theAsia Pacic Economic Cooperation (APEC) and the G8. TheEuropeanUnion, theUnitedKingdomandJapan, tonameafew,have spent considerable resources developing energy securitystrategies.3. Conceptualisations of energy securityTheenergysecurityliteratureismarkedbyaverydominantfocus on securing supplies of two primary energy sources, oil andgas(Forexample, see:IEA, 2008b, Isbell, 2007;M uller-Kraenner,2008, UNDP, 2004, Wesley, 2007). Yet electricity nowrankssecond only to oil in terms of nal energy consumption and is theworldsmost dominant formof energysupplytotheeconomymaking it critical to energy security (IEA, 2008a; Chang and LiangLee, 2008).Theliteratureisalsonotablymarkedbyvapidabstractionsfromaforeign-policycottageindustrythatobsessesabouttheneed for nations and their diplomats to worry about and attempttomanagepetroleummarkets (vanDoren, 2006: p. 186). Thispreponderancewithgeopolitics infers that theinternational orglobal realm is the only legitimate or relevant space for discourseabout energysecurity(Forexample, see: Grant, 2008; Houssin,2007; Kalicki andGoldwyn, 2005; Marquina, 2008; MoranandRussell, 2009; Naughten, 2008; Toichi, 2003; Yergin, 2005;Wesley,2007;Youngs,2007).3.1. Market-centricdenitionsBohi and Toman (1993: p. 1094) state that energy security canbedenedinvarious ways althoughtheir focus is limitedtoeconomicissues relatedtothebehaviour of markets. Subse-quentlytheydeneenergyinsecurityasthelossof economicwelfarethat mayoccur asaresult of achangeinthepriceoravailabilityofenergy (BohiandToman, 1996:p. 1). Someyearsearlier, the IEA dened energy security as an adequate supply ofenergyatareasonablecost (IEA, 1985:p. 29)andlaterpositedthatenergysecurityissimplyanotherwayof avoidingmarketdistortions (IEA, 1995: p. 23) because smoothly functioninginternational energymarkets will deliverasecureadequate,affordableand reliable supply of energy(IEA,2002: p. 3).This IEA denition of energy security in market terms has beenconsistently restated and most recently expressed as energysecurity alwaysconsistsofbothaphysicalunavailability compo-nent anda price component, (but) the relative importance ofthese depends on market structure (IEA, 2007a: p. 32). A similarapproach is mirrored by Stern (2007), the UK Government(DBERR, 2007a; DTI, 2006, 2007) andBielecki (2002: p. 237)whosuggeststhat theconcept iscentredonnotionsof supplyreliability and adequacy at reasonable market-determinedprices.Thelogicwhichunderpinsthesemarket-centric denitionsgoes something like this: as a consequence of the liberalisation ofenergy markets, energy security (and insecurity) is a marketoutcome, determined by the operation of the market and thus canonlybedenedinmarket termsparticularlysupply(physicalavailability) and price. Continuity of physical supplyoftendescribedintermsofavailability, reliability, relativeshortageorcomplete disruptionacross the total supplychainassumes asingular, unparalleledimportancewithinthis denitionof theconcept.A security of supply risk refers to a shortage in energy supply,either a relative shortage, i.e. a mismatch in supply anddemand inducing price increases, or a partial or completedisruption of energy supplies (Scheepers, Seebregts et al.,2006:p. 13).Therefore the purpose of energy security strategies is toovercome situations when energy markets do not functionproperlyy(and) shouldbemostlyaimedat makingmarketswork (No el, 2008). Competitive markets and independentregulationareconsideredthemosteffectivewayof deliveringsecure and reliable energy supplies (DBERR, 2007a: p. 8). Acorollary of this viewcomes strongly to the fore in the UKGovernmentsenergyapproach. Theright level of security(i.e.continuity of supply) depends on the balance between the costsandthe benets of increasing securityy(and) is left tothemarket as suppliers arebetter placedthangovernment or theregulatortounderstandthevaluethattheirdifferentcustomersplace onsecurity of supply (ibid:p. 17).3.2. QuantitativemeasurementAfurthercorollaryofthemarket-centricconceptualisationofenergysecurityhasbeensuccessiveendeavoursatitsoperatio-nalisation. The rst stepwas the translation of the market-centric denition into short-term(operational) and long-term(adequacy) threats to supply disruptions based on sources ofenergy supplies, and subsequent transit, storage and delivery (IEA,1995;Stern, 2002). Thesecondstepwasquanticationof theserisks. Tobeanalyticallyhelpful, ameasureof supplysecurityneeds to be quantiable (DBERR, 2007b: p. 2), can be used as aL.Chester/EnergyPolicy38(2010)887895 889ARTICLEINPRESSmeasuretoindicateadesiredstate (Scheepers, Seebregtsetal.,2006: p. 13) andcanmeasurerisks andpolicyeffectiveness(T onjes and de Jong, 2007). Even more recently it has beencontendedthat quantitativeindicators arenecessarytounder-stand the energy security consequences of different developmentpathways(Kruyt, vanVuuren et al., 2009: p. 1).Quantitative measurement of energy security risks hasgatheredpacesincetheearly partofthisdecade.Since2002theUK Government has published security-of-supply indicatorswhich range across three categories of supply and demandforecasts, market signals (e.g. forward prices for gas andelectricity) and market response (planned major new investments(JESS 2002; 2006). The Clingendael International Energy Pro-gramme has developed, in relation to the European Union, a CrisisCapability Index (for short-termsupply interruption) and aSupply/DemandIndex(Scheepers, Seebregtset al. 2006, 2007).The IEA (2004, 2007a) has also proposed energy securitymeasurement tools of physical availability(geopolitical energysecurity and pipe-based import dependence) and the pricecomponent (powersystem reliability andmarket power).Anotherexampleofthisquestforquanticationhasbeenanextension of the ShannonWiener index, an established non-parametric measure of ecological diversity (Stirling, 1998).Modications of this index have been used to construct indicatorsof energysourcediversity, import dependency, primaryenergydemandandpolitical stability(APERC, 2007; Jansen, vanArkelandBoots,2004; Neumann,2007).Other quantitative indicators to emerge have been an oilvulnerability index (Gupta, 2008), indicators of oil importdependency, Middle East oil import dependency and a non-carbon based fuel portfolio (APERC, 2007), a mathematicalexpressionof apenaltynotice, reectingthesocietal damage(Bollen,2008:p.21)fromenergyinsecurity,andclassicationofenergy security by ex-post (price development) and ex-ante(potential problem) indicators (L oschel, Moslener et al., 2009).Notably,arecentstudywent to afarmoremicrolevel andtestedtheenergysecurityof deregulatedelectricitymarketsbyestab-lishingquantitativeindicatorsforadequacyof generationcapa-city, reliability and reasonable price (Chang and Liang Lee, 2008).3.3. Broader denitionsencompassingqualitativeaspectsTheprogressiveendeavourstoquantifyenergysecurityraisetwo signicant points. First, as demonstrated by Kruyt, vanVuurenet al. (2009), the adoptionbypolicymakers of energysecurity indicators is virtually non-existent apart fromsomemarginal use in relation to oil and, as mentioned earlier, by the UKGovernment.1Secondly, broader denitions of energy security are observablewhich embrace dimensions other than market supply and marketprice. For example, the European Commissions Green PaperTowards a European strategy for the security of energy supply stated:energysupplysecuritymust begearedtoensuring, for thewell-beingof its citizens andtheproper functioningof theeconomy, the uninterrupted physical availability of energyproductsonthemarket, atapricewhichisaffordableforallconsumers(privateandindustrial), whilerespectingenviron-mental concerns and looking towards sustainable developmenty Securityofsupplydoesnotseektomaximiseenergyself-sufciency or to minimise dependence, but aims to reduce theriskslinkedto suchdependence(EC,2000:pp. 12,emphasisadded).The hazards posed to eachof these dimensions of energysecurity are identied, by the Green Paper, as physical, economic,social andenvironmental risks. Moreover, it is recognisedthatthese risks will not be ameliorated or prevented without governmentinterventionthrough policy and/or regulatory actiongiventhe complex institutional arrangements which guarantee theexistenceandfunctioning ofcontemporary energy markets.A similar viewis expressed in the European Parliamentsresponse to this Green Paper which highlights notions of adequatecapacity to meet demand, and availability through sourcediversication and many suppliers. The Parliaments responsestressesEuropeshighoilimportdependence, proposesareduc-tionintransportsdemandforoilbutcontendsthatdependenceon imports of energy fuels is neither necessarily a bad thing noreconomically inefcient provided the sources are diverse, not onesupplier isdominant andwecanproducesufcient goodsandservicesto pay forthem (EuropeanParliament,2001: p. 17).The dimensions of availability, affordability, adequate capacityandsustainabilityareechoedbytheAPERC(2007) andannualissues of the World Energy Assessment which denes energysecurity as the availability of energy at all times in various forms,insufcient quantitiesandataffordablepriceswithoutunaccep-tableorirreversibleimpact ontheenvironment (UNDP, 2004:p. 42, emphasis added).2These latter assessments distinguishbetweenshort andlongtermenergysupplyinterruptions, andstresstheneedfordiversicationof local andimportedenergysources to keep pace with expected growth in demand (Forexample: UNDP,2000:p. 113).TheAPERCsenergy security denition ofthe ability of an economy to guarantee the availability ofenergyresourcesupplyinasustainableandtimelymannerwiththeenergypricebeingatalevelthatwillnotadverselyaffecttheeconomicperformance ofthe economy (2007:p. 6)placestheconcept rmlywithinthecontext of thebroadereconomy. Similarly, Chevalier (2006: p. 2) suggests that thestandard denition yis a ow of energy supply to meet demandin a manner and at a price level that does not disrupt the course ofthe economy in an environmental sustainable manner. Boththese latter denitions also clearly infer the desirability forgovernmentaction shouldeconomicperformancebejeopardisedbyinsufcient, unsustainableandunaffordablemarketprovisionof energy.Table 1 summarises the dimensions of energy securityprioritisedbythenarrower market-centric andbroader multi-dimensional denitions as well as the endeavours toquantitativelymeasure energy security.4. Multiple aspects of energy securityA number of fundamental aspects about the termenergysecurity are discernible from thediscussion thus far.First, an inherent feature of energy security is about themanagementofrisktheriskofinterrupted, unavailableenergysupplies; the risk of insufcient capacity to meet demand; the riskofunaffordableenergyprices;theriskofrelianceonunsustain-able sources of energy. These risks maybe causedbyenergy1AlthoughtheUKGovernments indicators arenot mentioned, Kruyt, vanVuurenetal.(2009)doprovideanunparalleledsummaryoftherangeofsimpleandaggregatedindicatorsof energysecuritythat havebeendevisedinrecentyears.2Sustainabilityandacceptability(totheenvironment)arefoundtobeusedsynonymously inanumber ofpublications discussing energy security.L.Chester/EnergyPolicy38(2010)887895 890ARTICLEINPRESSmarket instabilities, technical failures or physical security threats(IEA,2007b).Asecondpointconcernstheextentto whichthedenitionofenergy security may be framed to reect a countrys (orcontinents) energyusemix, theabundanceof local resourcesand reliance on imports. This is illustrated by the ECs 2006 GreenPaperAEuropeanstrategyforsustainable, competitiveandsecureenergy. The document places a far stronger emphasis on thephysicalsecurityofsupply(networkinfrastructure, stock, diver-sication of supplies) than the Green Paper of six years earlier. Theobjective of supply security, now separated from sustainability, istargetedat tackling the EUs rising dependence onimportedenergy (EC, 2006: p. 18) projected to rise to around 70% of energyrequirements in the next 20 to 30 years. This dependence is to betackled by a number of policy measures such as reducingdemand, diversicationof theenergymixandsupplysources,stimulatinginvestmentinadequatecapacity, emergencyprepa-redness, andimprovedenergyaccessfor businessandcitizens.The clear priority of energy security is to minimise the EUs importvulnerability, supplyshortfallsandpotential supplyuncertaintygiven the high dependence on one single gas supplier (EC, 2007).Third, thetermenergysecurity clearlyreectsaconcept(anabstract idea) withsomeformof strategicintent. This viewisexempliedbythefollowingdenitiondevelopedbytheCentrefor EuropeanPolicy Studies: security of supplyconsists of avariety of approaches aimed at insuring against supply risks.Security of supply becomes a cost-effective risk-managementstrategyof governments, rmsandconsumers (EgenhoferandLegge, 2001: p. 3, emphasis added). The latter point aboutresponsibilityorcarriageofthestrategyiscontestableandgoesbeyond the purposes of the current discussion. The salient point isthat energysecurityisaconcept withstrategicintent.3Energysecurity is not a policy. Specic policy measures are implementedbygovernments toachievetheobjective(s) of energysecurity,however dened, and these policy measures have increasinglyincludedrelianceoncompetitivemarkets, thecreationof newregulatoryregimes tosupport thosemarkets, andgeopoliticalapproaches(Youngs, 2007).Fourth, the concept of energy security has a temporaldimension. Therisksorthreatstophysical supplydifferacrossshort, mediumandlongtermhorizons. Short-termrisksincludeextreme weather conditions, accidents, terrorismattacks, ortechnicalfailure. Themainissueofconcernisthereliabilityandcontinuity of available technological and commercial mechanismswhich convert primary energy sources for end-use by consumers.Long-term risks concern the adequacy of supply to meet demandandtheadequacyof infrastructuretodeliversupplytomarketswhich will, in turn, depend on levels of investment andcontracting, thedevelopmentof technologyandtheavailabilityof primary energy sources (Egenhofer, Gialoglu et al., 2004).Thereforethemeaningattributedtoenergysecuritywill differacross time because the probability, likelihood and consequencesof differentrisksor threats to supply will vary overtime.A fth aspect concerns the differences between energymarkets. Therearesignicant differences betweentheoil, gas,nuclear andelectricityenergymarkets suchas the rigidityoftransport infrastructure, the difculties of storage, and theregional natureof markets (IEA, 1995). Consequently, toapplytheconceptofenergysecuritytothegasmarketwillresultinadifferent meaning than if applied to the oil market or theelectricity market. These security-of-supply differences acrossenergymarkets were recognisedbythe IEAs 1995gas study,afrmedbytheUKGovernmentsdecisiontodevelopseparatesetsofsecurity-of-supplyindicatorsforeachenergymarketandreinforcedbytheelectricity-centricindicatorsdevelopedaspartofChangandLiangLees(2008)recentstudyofenergysecurityand deregulated electricitymarkets.Afurther aspect concernstheeyeof thebeholder, apointnoticeablymadebyAlhajji (2006), Birol (2006), andtheWorldEconomic Forum (2006). Different perspectives of energy securitywill be held by producers, large and small consumers, developingand developed countries, companiesoperatingwithin anetwork,policymakers and other energy stakeholders.Box1summarises thesemanyaspects of thetermenergysecurity andparticularly interms ofits contemporary usage.5. Market paradigms underpinning conceptualisations ofenergy securityA nal aspect about energy security is possibly the mostsignicant given the implications for the policy role and actions ofgovernments. As we have seen, a denition of energy security maycontain both absolute and relative notions. Availability andadequacy of capacity are capable of absolute measurement.Affordability, or the reasonableness of prices, are relative notionswithmeanings subject toconsiderablevariation. Supranationalorganisations, governments, policyadvisers andcommentatorsgenerallyfavour adenitionof energysecuritycentredontheabsolute notions of market supply and market price. Broaderdenitions, suchas those usedby the EuropeanCommission,encompass absolute and relative notions. All denitions envisagethe market playing a central role in ensuring, enhancing orattaining energy security. However, what is the market paradigmunderpinning these denitions?Two competing market paradigms are evident withincon-temporaryeconomicthought:thepureWalrasianmarketwhichoptimallyallocates products inaperfectlyinformed, atomisticworld; or themarket whichisasocial, political andhistoricalconstruct (Chang, 2002; Coriat and Weinstein, 2005). Eachparadigm denes the interrelationship between market and state,and thus the role to be played by policy to deal with matters suchasenergy security.Table 1Dimensionsprioritised inenergy securitydenitionsandquantitativemeasures.Dimensions of energy security Market-centric denitions Quantitative measurement Broader denitionsAbsolute:Availability | | |Adequacy of capacity | |Relative:Affordability |Sustainability |3The IEA (2002) and Jenny (2007) contend that energy security is an evolvingconcept because it now includes a range of energy sources other than oil, a widerange of risks along the supply chain, and price as well as supply availability. This, Iwould contend, amounts to a concretisation of the concept and it is the contentionof this article that the application or usage of the concept has evolved over timeto reect multipleaspects.L.Chester/EnergyPolicy38(2010)887895 891ARTICLEINPRESSThe narrower market-centric denition of energy securityclearly is based on the pure Walrasian market with its self-equilibratingproperties. Marketsareassumedtoclearautomati-cally via price adjustments i.e. prices respond to changes indemandorsupply, ndingequilibriumatthepriceatwhichthequantitysuppliedequalsthequantitydemanded. Theseoscilla-tions, accordingtothisparadigm, underpinasystemicstabilityacrossmarketsforallgoodsandservicesandensureanoptimalallocationof resourcesbetweencompetingneeds. Yet thisself-equilibratingnatureof themarket restsonnumerousassump-tions suchas identical consumers behavingrationallybecausetheyareperfectlyinformedabout all theavailablealternatives,zerotransactioncosts, notradingat disequilibriumprices, andinnitelyrapidvelocitiesof pricesandquantities(Blaug, 2002:pp.4041).Notwithstanding anyperceivedincompatibilityof these as-sumptionswitheconomicreality, thisparadigmmaintainsthatthe market should be left unfetteredfrom stateinterventions toensureitsefcient workingsareallowedtodetermineoutputand price. The market-centric denitionof energy security iscouchedinthesemarkettermsofoutput(supply)andpriceandenergy security policies should be mostly aimed at makingmarkets work and letting them work when they do (No el, 2008).Thisapproachstrongly advocatesalimitedroleforgovernmentsandpolicy.Energymarketsshouldbeallowedtooperatefreely.Competitively determined output and prices should be the energysecurity objectivesofgovernments.Adequacy ofcapacity,afford-abilityandsustainabilitywill naturallyfollowasby-productsofanunfettered marketbutthesacrosanctobjectivesofcompeti-tive output and prices will be jeopardised if governmentsintervene inthepursuit oflower-order objectives.Not surprisingly, adifferent viewis heldbythealternativemarket paradigmwhichsituatesthemarket asoneof amulti-plicity offormal andinformal institutions comprising capitalism.All institutions, including the market yare dened in relation tothestructureof therights andobligations of therelevant actors(Chang, 2007:p. 7)whichinthecaseofthemarketincludestheinstitutional arrangements that determine and/or regulate marketparticipants,andtheobjectsandprocessofmarket exchange.Asthese rights and obligations are deemed to be the result ofpolitics, themarketlikeallinstitutionsisconsideredtobeapolitical construct. Property rights, and the entitlements be-stowed on market participants are not free of politics, nor are thedetermination of interest rates and wages which impact on everysector of the economy, along withnumerous state actions toprotect market participants. Farfrombeingnatural, marketsare the fruit of complex social and historical developments(Coriat and Weinstein, 2005: p. 1) with politics, and thus the state,being integralto their creationand functioning.Consequently, the institutionalist paradigm assigns a far moreactive role to the state in relation to the market. Market outcomesresult from a myriad of institutional arrangements and processesall of which are inuenced by the state and politics. Accordingly, aviewof market outcomes solelyinterms of output andpriceprovides a partial and thus inaccurate view, of reality. Thecorollaryof this paradigmis that energy markets needtobeconsidered througha multi-dimensional lens which goes beyondthe absolute market notions of output and price to include notionssuchasadequacyofcapacitytomeetdemand, affordabilityandsustainability. Thisapproachismoreconsistentwiththedeni-tionof energysecurityadoptedby, for example, theEuropeanCommissionandreectedinthepolicypositionsofEUmemberstates.6. Implications of energy securitys multi-dimensional natureand specicitiesWithinaliteratureskewedheavilytowards viewingenergysecurity through the prism of geopolitics and the supply of oil, theapparent or inferred denitions of energy security have beenfoundtofallintooneoftwobroadcategories. Therstcategorycentres on market supply and energy availability at market price.The second category is broader taking into account moredimensions.Within each of these denitional categories, the foregoingdiscussion has also shown that multiple meanings can beattributedtothetermenergysecurity. Itsmeaningmaybeusedtoconveyabsoluteandrelativenotionsdenotingdimensionsofavailability, adequacy of capacity, affordability and/or sustain-ability (Refer Table 1). Those favouring the narrower market-centric denition place an almost exclusive priority on theabsolutedimensionof availabilityi.e. physical supply(althoughnotions around adequate capacity may be mentioned) andaffordabilityiseschewed, notonlyduetoitsinherentrelativitybut becauseit is generallyassumedthat market pricereectsenergy availability and thus the cost of security of supply (Behrensand Egenhofer, 2008). Possibly the narrowest market-centricdenitionof energysecurityisthat positedbyNo el (2008) asenergy availability to those willing to pay the marketprice.The adoptionbygovernment of a narrowmarket-basedorbroader multi-dimensional denition of energy security providesanunequivocalsignalofitsintendedrolevis- a-visthemarketinthe pursuit of energy security objectives. Energy market outcomesare either viewed purely in absolute market terms or morebroadly. Iftheformer, governmentsmaywellfocusonreducingmarket obstacles andimperfections throughregulation. If thelatter, governments maywell intervenetoadjust market out-comes. For example, with respect to market price and theaffordability of energy prices, governmentmay provide subsidiesfor low income groups such as the UK Governments fuel povertyprogramme (DBERR, 2001); with respect to sustainability, govern-ments may seek to discourage the use of high-emission fossil fuelsthroughmechanisms such astheEUcap-and-trade scheme.The discussion has also shown that energy security is a conceptnot a policy. Policies may be directed at implementing a strategicintent toalleviate energy insecuritywhichoftenis framedinterms of: (1) the management of perceived risk(s)to avoidBox1Multipleaspectsofthetermenergysecurity.y Energysecurityisaboutthemanagementofrisk(s).y Energysecuritycanrefertoenergyusemix,abundanceoflocalresources,and/ortherelianceonimports.y Energysecurityisaconcept,notapolicy,withstrategicintent.y Policiesareimplementedtoimproveenergysecurity.y Energysecuritycanholdatemporaldimension.y Energysecuritywilldifferbetweenacrossenergymarkets.y Energysecuritywilldifferbetweenenergymarketstakeholders.L.Chester/EnergyPolicy38(2010)887895 892ARTICLEINPRESSsupply disruption, insufcient capacity, unaffordability, andrelianceonunsustainableenergysources, and/or(2)acountrysenergy use mix and reliance on local resources or imports.Application of the concept of energy security has evolved tohave relevance across the worlds energy regime of a vastcomplexnetworkof energysupplysystems fromupstreamtodownstream.Thetimehorizonadds afurther layer of complexitytothemeaning of energysecurity because whatever dimensions areusedtodenetheterm,therisksorthreatsto thosedimensionswill differ intheshort termfromthemediumandlongterm.Finally, the heterogeneity between energy markets means that theapplicationof theconcept will result indifferent meaningsfordifferent energy sourcesanddifferentstakeholders.These ndings lead to the contention that the concept ofenergysecurityisinherentlyslipperybecauseitispolysemicinnature. The concept has many possible meanings. Energy securitymaybedelineatedthroughmultipledimensionsandittakesondifferent specicities dependingonthecountry(or continent),timeframeor energy source to which it isapplied.This slipperiness, and the inherent prediction and policydifculties that this poses, has been noted in the context ofsurgingoil pricesandthegovernanceofliberalisedgasmarkets(Isbell, 2007; Wright, 2005).Brennan (2007: p. 3)also alluded tothesedifculties, inthecontext of electricity, whensuggestingrather than adopt one at the risk of excluding others, it is usefulto have asareferencepointasmany ofthese differentmeaningsasisreasonable.Onepossibleapproachtoassessacountrys(orcontinents)energy security over the short and long term, encompassingBrennans notion of a multiple meaning reference point, is to usea four-dimensional grid of availability, adequacy of capacity,affordabilityandsustainabilityfullycognisant that thelevel ofdisaggregationwouldneedtobeat eachenergysource.4Thisapproachconceptualisestheissueofenergysecuritybroadlyyetexplicitly recognises the temporal aspect and energy marketheterogeneity. Suchanapproachdoesnot presupposethat onedimensionisthesoleorprimarydeterminant ofenergy security.Suchanapproachdoes, however, inferthatall fourdimensionscontribute to some degree to energy security. Such anapproach also recognises many of the polysemic layers inwhichenergysecurityis swathed. It alsoresponds tothecallformoreholisticconceptualisationsofenergysecurity (ChangandLiangLee, 2008: p. 100) despitethecomplexityposedforanalysis and allows for the application of multiple indicatorsleadingtoabroader understanding (Kruyt, vanVuurenet al.,2009:p. 1).But thepolysemic qualities of energysecurityposefurtherimplications. First, these qualities demonstrate the impracticalityof seeking a common denition of energy security for which somehave yearned (Alhajji, 2006; Cabalu, Alfonso et al., 2008).Conceptualisationof energysecurityataglobal level comparedtoregional, national, global, producer or consumer levels maycontain similar notions of availability, adequacy, affordability andsustainabilitybut thespecicities of eachwill understandablydifferatanypointintime. All holdequal validitybuteachwillexpress the concept of energy security in terms of their respectivesphere. No one sphere can appropriate energy security as its owndespitetheglobal spheredominatingtheliteraturebecausetheissue of energy security does not start or stop at national bordersor only hold signicance for a particular group of countries giventhe worlds energy appetite, the location of energy sources(primaryandenduse)andtheoperationofsub-nationalenergymarkets.Second, energy security is akin to a wicked problem which isnot amenable to traditional linear, analytical approaches orresolutionbythesystematic applicationof technical expertise(Chester, 2009; Goodin, Rein and Moran, 2006; Rittel and Webber,1973)5. Consequently strategies and specic policies to deal withenergy security require newways of thinking and pose sub-stantive challenges to governance structures, skills bases andorganisational capacities.Moreover, themultiplicity ofmeaningsthatcanbeattributedto energy security establishes thatthere canbenoone-size-ts-all solution. For example, the policy measures designed to reduceacountrys energyimport dependencewill differ considerablyfrom the policy measures aimed at improving energy affordability.Bothcanbedenotedasdimensionsofenergysecuritybuteachrequiresconsiderablydifferentpolicyformulation, policyinstru-ments and implementation given the vast difference in the natureand scaleof impactsought.Thetemporal dimensionof energysecurityalsosignals theimpossibility of an absolute or clear end-state solution. Themeaningof energysecuritydiffersovertheshort, mediumandlong term because the probability, likelihood and consequences ofdifferentrisksorthreatstosupplywillvaryovertime. Thuswewill never reachanend-state of energy security as such. Ananalogous situationis the process of competition. Firms con-tinually seekto createandmaintainthebestconditionsfortheirprotability. To do this, rms will continually seek out and exploitdifferences in technology, production, distribution, access toinformation and consumption trends. It is an ongoing never-ending process. Likewise policymakers and governments will takeactions seeking to address short and long term obstacles deemedtobeimpactingonenergysecurity. But thefactorsinuencingenergysecurity, however it is dened, areconstantlychanging.Hence, anend-stateofenergysecurityisneverreachedbecauseitsnature iscontinually evolving.As stated at the outset, the purpose of this article is to addressalacunaintheliterature, namelydiscussionabouttheconcep-tualisation of energy security. This isnot a plea forsome form ofstandardised conceptualisation, the folly of which is evident givenenergysecuritys polysemic qualities expoundedinthis articlethat have emerged fromthe evolving political, economic andsocial context of the contemporary energy regime. There is,however, apleainherent tothis articlefor robust debateanddiscussion about the use of the term. Those who engage with thediscourse, including policymakers, should openly present thesuppositions, assertions, or premises whichinformandshapetheir useof theconcept. Denitional claritywill enrichdebateabout policies to deal with obstacles impacting on the constantlyevolvingnatureof energysecurity, as it applies toarangeofspheres other thanthe global, as well as reachnewlevels ofunderstanding about thispolysemicconcept.ReferencesAlhajji, A.F., 2006. The meaning of energy security. USAEE Blog, Posted 22 August.Retrieved 12November 2008from /http://blog.usaee.org/?q=node/8#topS.AsiaPacicEnergy Research Centre (APERC),2007. 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