Gasoline - Wikipedia

"Gasoline" is an English word that denotes fuel for automobiles. The term is thought to have been influenced by the trademark "Cazeline" or "Gazeline", named ... Gasoline FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Transparent,petroleum-derivedliquidusedprimarilyasfuel Forotheruses,seeGasoline(disambiguation). "Petrol"redirectshere.Forotheruses,seePetrol(disambiguation). Gasolineinamasonjarmeasuringroughly700 mL(24U.S.fluidounces) AtypicalgasolinecontainerofUSAholds1.0U.S.gallon(3.8 L). Gasoline(AmericanEnglish;/ˈɡæsəliːn/)orpetrol(BritishEnglish;/ˈpɛtrəl/)(seeEtymologyfornamingdifferencesandgeographicusage)isatransparent,petroleum‑derivedflammableliquidthatisusedprimarilyasafuelinmostspark-ignitedinternalcombustionengines(alsoknownaspetrolengines).Itconsistsmostlyoforganiccompoundsobtainedbythefractionaldistillationofpetroleum,enhancedwithavarietyofadditives.Onaverage,a160-liter(42-U.S.-gallon)barrelofcrudeoilcanyielduptoabout72liters(19U.S.gallons)ofgasolineafterprocessinginanoilrefinery,dependingonthecrudeoilassayandonwhatotherrefinedproductsarealsoextracted.[1] Thecharacteristicofaparticulargasolineblendtoresistignitingtooearly(whichcausesknockingandreducesefficiencyinreciprocatingengines)ismeasuredbyitsoctanerating,whichisproducedinseveralgrades.Tetraethylleadandotherleadcompounds,oncewidelyusedtoincreaseoctaneratings,arenolongerusedexceptinaviation[2] andoff-roadandauto-racingapplications.[3]Otherchemicalsarefrequentlyaddedtogasolinetoimprovechemicalstabilityandperformancecharacteristics,controlcorrosiveness,andprovidefuelsystemcleaning.Gasolinemaycontainoxygen-containingchemicalssuchasethanol,MTBE,orETBEtoimprovecombustion. Gasolinecanentertheenvironment(uncombusted),bothasliquidandasvapor,fromleakageandhandlingduringproduction,transport,anddelivery(e.g.,fromstoragetanks,fromspills,etc.).Asanexampleofeffortstocontrolsuchleakage,manyundergroundstoragetanksarerequiredtohaveextensivemeasuresinplacetodetectandpreventsuchleaks.[4]Gasolinecontainsknowncarcinogens.[5][6][7]Burning1liter(0.26 U.S. gal)ofgasolineemitsabout2.3kilograms(5.1 lb)ofCO2,agreenhousegas,contributingtohuman-causedclimatechange.[8][9] Contents 1Etymology 2History 2.11903to1914 2.2WorldWarI 2.3UnitedStates,1918–1929 2.4Leadedgasolinecontroversy,1924–1925 2.5UnitedStates,1930–1941 2.6WorldWarII 2.6.1Germany 2.6.2Japan 2.6.3UnitedStates 2.7UnitedStates,1946topresent 3Chemicalanalysisandproduction 4Physicalproperties 4.1Density 4.2Stability 4.3Combustionenergycontent 5Octanerating 6Additives 6.1Antiknockadditives 6.1.1Tetraethyllead 6.1.2Leadreplacementpetrol 6.1.3MMT 6.2Fuelstabilizers(antioxidantsandmetaldeactivators) 6.3Detergents 6.4Ethanol 6.4.1EuropeanUnion 6.4.2Brazil 6.4.3Australia 6.4.4UnitedStates 6.4.5India 6.5Dyes 6.6Oxygenateblending 7Safety 7.1Toxicity 7.2Inhalationforintoxication 7.3Flammability 7.4Gasolineexhaust 8Environmentalimpact 8.1Carbondioxide 8.2Contaminationofsoilandwater 9Useandpricing 9.1Europe 9.2UnitedStates 10Gasolineproductionbycountry 11Comparisonwithotherfuels 12Seealso 13Notes 14References 14.1Bibliography 15Externallinks Etymology[edit] "Gasoline"isanEnglishwordthatdenotesfuelforautomobiles.Thetermisthoughttohavebeeninfluencedbythetrademark"Cazeline"or"Gazeline",namedafterthesurnameofBritishpublisher,coffeemerchant,andsocialcampaignerJohnCassell.On27November1862,CassellplacedanadvertisementinTheTimesofLondon: ThePatentCazelineOil,safe,economical,andbrilliant…possessesalltherequisiteswhichhavesolongbeendesiredasameansofpowerfulartificiallight.[10]Thisistheearliestoccurrenceofthewordtohavebeenfound.CasselldiscoveredthatashopkeeperinDublinnamedSamuelBoydwassellingcounterfeitcazelineandwrotetohimtoaskhimtostop.Boyddidnotreplyandchangedevery‘C’intoa‘G’,thuscoiningtheword"gazeline".[10]TheOxfordEnglishDictionarydatesitsfirstrecordeduseto1863whenitwasspelled"gasolene".Theterm"gasoline"wasfirstusedinNorthAmericain1864.[11] InmostCommonwealthcountries(exceptCanada),theproductiscalled"petrol",ratherthan"gasoline".Thewordpetroleum,originallyusedtorefertovarioustypesofmineraloilsandliterallymeaning"rockoil",comesfromMedievalLatinpetroleum(petra,"rock",andoleum,"oil").[12][13]"Petrol"wasusedasaproductnameinabout1870,asthenameofarefinedmineraloilproductsoldbyBritishwholesalerCarless,Capel&Leonard,whichmarketeditasasolvent.[14]Whentheproductlaterfoundanewuseasamotorfuel,FrederickSimms,anassociateofGottliebDaimler,suggestedtoJohnLeonard,theownerofCarless,thattheyregisterthetrademark"Petrol",[15]butbythattimethewordwasalreadyingeneraluse,possiblyinspiredbytheFrenchpétrole,[16]andtheregistrationwasnotallowedbecausethewordwasageneraldescriptor;Carlesswasstillabletodefenditsuseof"Petrol"asaproductnameduetotheirhavingsolditunderthatnameformanyyearsbythen.Carlessregisteredanumberofalternativenamesfortheproduct,but"petrol"nonethelessbecamethecommontermforthefuelintheBritishCommonwealth.[17][18] Britishrefinersoriginallyused"motorspirit"asagenericnamefortheautomotivefueland"aviationspirit"foraviationgasoline.WhenCarlesswasdeniedatrademarkon"petrol"inthe1930s,itscompetitorsswitchedtothemorepopularname"petrol".However,"motorspirit"hadalreadymadeitswayintolawsandregulations,sothetermremainsinuseasaformalnameforpetrol.[19][20]ThetermisusedmostwidelyinNigeria,wherethelargestpetroleumcompaniescalltheirproduct"premiummotorspirit".[21]Although"petrol"hasmadeinroadsintoNigerianEnglish,"premiummotorspirit"remainstheformalnamethatisusedinscientificpublications,governmentreports,andnewspapers.[22] TheuseofthewordgasolineinsteadofpetrolisuncommonoutsideNorthAmerica,[23]althoughgasolinaisusedinSpanishandPortuguese. Inmanylanguages,thenameoftheproductisderivedfrombenzene,suchasBenzininPersianandGermanorbenzinainItalian;butinArgentina,Uruguay,andParaguay,thecolloquialnamenaftaisderivedfromthatofthechemicalnaphtha.[24] Somelanguages,likeFrenchandItalian,usetherespectivewordsforgasolinetoindicatedieselfuel.[25][26] History[edit] Thefirstinternalcombustionenginessuitableforuseintransportationapplications,so-calledOttoengines,weredevelopedinGermanyduringthelastquarterofthe19thcentury.Thefuelfortheseearlyengineswasarelativelyvolatilehydrocarbonobtainedfromcoalgas.Withaboilingpointnear85 °C(185 °F)(n-octaneboilsabout40 °Chigher),itwaswell-suitedforearlycarburetors(evaporators).Thedevelopmentofa"spraynozzle"carburetorenabledtheuseoflessvolatilefuels.Furtherimprovementsinengineefficiencywereattemptedathighercompressionratios,butearlyattemptswereblockedbytheprematureexplosionoffuel,knownasknocking. In1891,theShukhovcrackingprocessbecametheworld'sfirstcommercialmethodtobreakdownheavierhydrocarbonsincrudeoiltoincreasethepercentageoflighterproductscomparedtosimpledistillation. 1903to1914[edit] Theevolutionofgasolinefollowedtheevolutionofoilasthedominantsourceofenergyintheindustrializingworld.BeforeWorldWarOne,Britainwastheworld'sgreatestindustrialpoweranddependedonitsnavytoprotecttheshippingofrawmaterialsfromitscolonies.Germanywasalsoindustrializingand,likeBritain,lackedmanynaturalresourceswhichhadtobeshippedtothehomecountry.Bythe1890s,GermanybegantopursueapolicyofglobalprominenceandbeganbuildinganavytocompetewithBritain's.Coalwasthefuelthatpoweredtheirnavies.ThoughbothBritainandGermanyhadnaturalcoalreserves,newdevelopmentsinoilasafuelforshipschangedthesituation.Coal-poweredshipswereatacticalweaknessbecausetheprocessofloadingcoalwasextremelyslowanddirtyandlefttheshipcompletelyvulnerabletoattack,andunreliablesuppliesofcoalatinternationalportsmadelong-distancevoyagesimpractical.Theadvantagesofpetroleumoilsoonfoundthenaviesoftheworldconvertingtooil,butBritainandGermanyhadveryfewdomesticoilreserves.[27]BritaineventuallysolveditsnavaloildependencebysecuringoilfromRoyalDutchShellandtheAnglo-PersianOilCompanyandthisdeterminedfromwhereandofwhatqualityitsgasolinewouldcome. Duringtheearlyperiodofgasolineenginedevelopment,aircraftwereforcedtousemotorvehiclegasolinesinceaviationgasolinedidnotyetexist.Theseearlyfuelsweretermed"straight-run"gasolinesandwerebyproductsfromthedistillationofasinglecrudeoiltoproducekerosene,whichwastheprincipalproductsoughtforburninginkerosenelamps.Gasolineproductionwouldnotsurpasskeroseneproductionuntil1916.Theearlieststraight-rungasolinesweretheresultofdistillingeasterncrudeoilsandtherewasnomixingofdistillatesfromdifferentcrudes.Thecompositionoftheseearlyfuelswasunknownandthequalityvariedgreatlyascrudeoilsfromdifferentoilfieldsemergedindifferentmixturesofhydrocarbonsindifferentratios.Theengineeffectsproducedbyabnormalcombustion(engineknockingandpre-ignition)duetoinferiorfuelshadnotyetbeenidentified,andasaresult,therewasnoratingofgasolineintermsofitsresistancetoabnormalcombustion.ThegeneralspecificationbywhichearlygasolinesweremeasuredwasthatofspecificgravityviatheBauméscaleandlaterthevolatility(tendencytovaporize)specifiedintermsofboilingpoints,whichbecametheprimaryfocusesforgasolineproducers.TheseearlyeasterncrudeoilgasolineshadrelativelyhighBaumétestresults(65to80degreesBaumé)andwerecalledPennsylvania"High-Test"orsimply"High-Test"gasolines.Thesewouldoftenbeusedinaircraftengines. By1910,increasedautomobileproductionandtheresultantincreaseingasolineconsumptionproducedagreaterdemandforgasoline.Also,thegrowingelectrificationoflightingproducedadropinkerosenedemand,creatingasupplyproblem.Itappearedthattheburgeoningoilindustrywouldbetrappedintoover-producingkeroseneandunder-producinggasolinesincesimpledistillationcouldnotaltertheratioofthetwoproductsfromanygivencrude.Thesolutionappearedin1911whenthedevelopmentoftheBurtonprocessallowedthermalcrackingofcrudeoils,whichincreasedthepercentyieldofgasolinefromtheheavierhydrocarbons.Thiswascombinedwiththeexpansionofforeignmarketsfortheexportofsurpluskerosenewhichdomesticmarketsnolongerneeded.Thesenewthermally"cracked"gasolineswerebelievedtohavenoharmfuleffectsandwouldbeaddedtostraight-rungasolines.TherealsowasthepracticeofmixingheavyandlightdistillatestoachievethedesiredBauméreadingandcollectivelythesewerecalled"blended"gasolines.[28] Gradually,volatilitygainedfavorovertheBaumétest,thoughbothwouldcontinuetobeusedincombinationtospecifyagasoline.AslateasJune1917,StandardOil(thelargestrefinerofcrudeoilintheUnitedStatesatthetime)statedthatthemostimportantpropertyofagasolinewasitsvolatility.[29]Itisestimatedthattheratingequivalentofthesestraight-rungasolinesvariedfrom40to60octaneandthatthe"High-Test",sometimesreferredtoas"fightinggrade",probablyaveraged50to65octane.[30] WorldWarI[edit] PriortotheAmericanentryintoWorldWarI,theEuropeanAlliesusedfuelsderivedfromcrudeoilsfromBorneo,Java,andSumatra,whichgavesatisfactoryperformanceintheirmilitaryaircraft.WhentheUnitedStatesenteredthewarinApril1917,theU.S.becametheprincipalsupplierofaviationgasolinetotheAlliesandadecreaseinengineperformancewasnoted.[31]Soonitwasrealizedthatmotorvehiclefuelswereunsatisfactoryforaviation,andafterthelossofseveralcombataircraft,attentionturnedtothequalityofthegasolinesbeingused.Laterflighttestsconductedin1937showedthatanoctanereductionof13points(from100downto87octane)decreasedengineperformanceby20percentandincreasedtake-offdistanceby45percent.[32]Ifabnormalcombustionweretooccur,theenginecouldloseenoughpowertomakegettingairborneimpossibleandatake-offrollbecameathreattothepilotandaircraft. On2August1917,theUnitedStatesBureauofMinesarrangedtostudyfuelsforaircraftincooperationwiththeAviationSectionoftheU.S.ArmySignalCorpsandageneralsurveyconcludedthatnoreliabledataexistedfortheproperfuelsforaircraft.Asaresult,flighttestsbeganatLangley,McCookandWrightfieldstodeterminehowdifferentgasolinesperformedunderdifferentconditions.Thesetestsshowedthatincertainaircraft,motorvehiclegasolinesperformedaswellas"High-Test"butinothertypesresultedinhot-runningengines.ItwasalsofoundthatgasolinesfromaromaticandnaphthenicbasecrudeoilsfromCalifornia,SouthTexas,andVenezuelaresultedinsmooth-runningengines.Thesetestsresultedinthefirstgovernmentspecificationsformotorgasolines(aviationgasolinesusedthesamespecificationsasmotorgasolines)inlate1917.[33] UnitedStates,1918–1929[edit] Enginedesignersknewthat,accordingtotheOttocycle,powerandefficiencyincreasedwithcompressionratio,butexperiencewithearlygasolinesduringWorldWarIshowedthathighercompressionratiosincreasedtheriskofabnormalcombustion,producinglowerpower,lowerefficiency,hot-runningengines,andpotentiallysevereenginedamage.Tocompensateforthesepoorfuels,earlyenginesusedlowcompressionratios,whichrequiredrelativelylarge,heavyengineswithlimitedpowerandefficiency.TheWrightbrothers'firstgasolineengineusedacompressionratioaslowas4.7-to-1,developedonly8.9kilowatts(12 hp)from3,290cubiccentimetres(201 cu in),andweighed82kilograms(180 lb).[34][35]Thiswasamajorconcernforaircraftdesignersandtheneedsoftheaviationindustryprovokedthesearchforfuelsthatcouldbeusedinhigher-compressionengines. Between1917and1919,theamountofthermallycrackedgasolineutilizedalmostdoubled.Also,theuseofnaturalgasolineincreasedgreatly.Duringthisperiod,manyU.S.statesestablishedspecificationsformotorgasolinebutnoneoftheseagreedandtheywereunsatisfactoryfromonestandpointoranother.Largeroilrefinersbegantospecifyunsaturatedmaterialpercentage(thermallycrackedproductscausedgumminginbothuseandstoragewhileunsaturatedhydrocarbonsaremorereactiveandtendtocombinewithimpuritiesleadingtogumming).In1922,theU.S.governmentpublishedthefirstspecificationsforaviationgasolines(twogradesweredesignatedas"Fighting"and"Domestic"andweregovernedbyboilingpoints,color,sulfurcontent,andagumformationtest)alongwithone"Motor"gradeforautomobiles.Thegumtestessentiallyeliminatedthermallycrackedgasolinefromaviationusageandthusaviationgasolinesrevertedtofractionatingstraight-runnaphthasorblendingstraight-runandhighlytreatedthermallycrackednaphthas.Thissituationpersisteduntil1929.[36] Theautomobileindustryreactedtotheincreaseinthermallycrackedgasolinewithalarm.Thermalcrackingproducedlargeamountsofbothmono-anddiolefins(unsaturatedhydrocarbons),whichincreasedtheriskofgumming.[37]Also,thevolatilitywasdecreasingtothepointthatfueldidnotvaporizeandwasstickingtosparkplugsandfoulingthem,creatinghardstartingandroughrunninginwinterandstickingtocylinderwalls,bypassingthepistonsandrings,andgoingintothecrankcaseoil.[38]Onejournalstated,"...onamulti-cylinderengineinahigh-pricedcarwearedilutingtheoilinthecrankcaseasmuchas40percentina200-milerun,astheanalysisoftheoilintheoil-panshows."[39] Beingveryunhappywiththeconsequentreductioninoverallgasolinequality,automobilemanufacturerssuggestedimposingaqualitystandardontheoilsuppliers.Theoilindustryinturnaccusedtheautomakersofnotdoingenoughtoimprovevehicleeconomy,andthedisputebecameknownwithinthetwoindustriesas"TheFuelProblem".Animositygrewbetweentheindustries,eachaccusingtheotherofnotdoinganythingtoresolvematters,andtheirrelationshipdeteriorated.ThesituationwasonlyresolvedwhentheAmericanPetroleumInstitute(API)initiatedaconferencetoaddress"TheFuelProblem"andaCooperativeFuelResearch(CFR)Committeewasestablishedin1920,tooverseejointinvestigativeprogramsandsolutions.Apartfromrepresentativesofthetwoindustries,theSocietyofAutomotiveEngineers(SAE)alsoplayedaninstrumentalrole,withtheU.S.BureauofStandardsbeingchosenasanimpartialresearchorganizationtocarryoutmanyofthestudies.Initially,alltheprogramswererelatedtovolatilityandfuelconsumption,easeofstarting,crankcaseoildilution,andacceleration.[40] Leadedgasolinecontroversy,1924–1925[edit] Withtheincreaseduseofthermallycrackedgasolinescameanincreasedconcernregardingitseffectsonabnormalcombustion,andthisledtoresearchforantiknockadditives.Inthelate1910s,researcherssuchasA.H.Gibson,HarryRicardo,ThomasMidgleyJr.,andThomasBoydbegantoinvestigateabnormalcombustion.Beginningin1916,CharlesF.KetteringofGeneralMotorsbeganinvestigatingadditivesbasedontwopaths,the"highpercentage"solution(wherelargequantitiesofethanolwereadded)andthe"lowpercentage"solution(whereonly2–4gramspergallonwereneeded).The"lowpercentage"solutionultimatelyledtothediscoveryoftetraethyllead(TEL)inDecember1921,aproductoftheresearchofMidgleyandBoydandthedefiningcomponentofleadedgasoline.Thisinnovationstartedacycleofimprovementsinfuelefficiencythatcoincidedwiththelarge-scaledevelopmentofoilrefiningtoprovidemoreproductsintheboilingrangeofgasoline.EthanolcouldnotbepatentedbutTELcould,soKetteringsecuredapatentforTELandbeganpromotingitinsteadofotheroptions. Thedangersofcompoundscontainingleadwerewell-establishedbythenandKetteringwasdirectlywarnedbyRobertWilsonofMIT,ReidHuntofHarvard,YandellHendersonofYale,andErikKrauseoftheUniversityofPotsdaminGermanyaboutitsuse.Krausehadworkedontetraethylleadformanyyearsandcalledit"acreepingandmaliciouspoison"thathadkilledamemberofhisdissertationcommittee.[41][42]On27October1924,newspaperarticlesaroundthenationtoldoftheworkersattheStandardOilrefinerynearElizabeth,NewJerseywhowereproducingTELandweresufferingfromleadpoisoning.By30October,thedeathtollhadreachedfive.[42]InNovember,theNewJerseyLaborCommissionclosedtheBaywayrefineryandagrandjuryinvestigationwasstartedwhichhadresultedinnochargesbyFebruary1925.LeadedgasolinesaleswerebannedinNewYorkCity,Philadelphia,andNewJersey.GeneralMotors,DuPont,andStandardOil,whowerepartnersinEthylCorporation,thecompanycreatedtoproduceTEL,begantoarguethattherewerenoalternativestoleadedgasolinethatwouldmaintainfuelefficiencyandstillpreventengineknocking.Afterseveralindustry-fundedflawedstudiesreportedthatTEL-treatedgasolinewasnotapublichealthissue,thecontroversysubsided.[42] UnitedStates,1930–1941[edit] Inthefiveyearspriorto1929,agreatamountofexperimentationwasconductedondifferenttestingmethodsfordeterminingfuelresistancetoabnormalcombustion.Itappearedengineknockingwasdependentonawidevarietyofparametersincludingcompression,ignitiontiming,cylindertemperature,air-cooledorwater-cooledengines,chambershapes,intaketemperatures,leanorrichmixtures,andothers.Thisledtoaconfusingvarietyoftestenginesthatgaveconflictingresults,andnostandardratingscaleexisted.By1929,itwasrecognizedbymostaviationgasolinemanufacturersandusersthatsomekindofantiknockratingmustbeincludedingovernmentspecifications.In1929,theoctaneratingscalewasadopted,andin1930,thefirstoctanespecificationforaviationfuelswasestablished.Inthesameyear,theU.S.ArmyAirForcespecifiedfuelsratedat87octaneforitsaircraftasaresultofstudiesithadconducted.[43] Duringthisperiod,researchshowedthathydrocarbonstructurewasextremelyimportanttotheantiknockingpropertiesoffuel.Straight-chainparaffinsintheboilingrangeofgasolinehadlowantiknockqualitieswhilering-shapedmoleculessuchasaromatichydrocarbons(forexamplebenzene)hadhigherresistancetoknocking.[44]Thisdevelopmentledtothesearchforprocessesthatwouldproducemoreofthesecompoundsfromcrudeoilsthanachievedunderstraightdistillationorthermalcracking.Researchbythemajorrefinersledtothedevelopmentofprocessesinvolvingisomerizationofcheapandabundantbutanetoisobutane,andalkylationtojoinisobutaneandbutylenestoformisomersofoctanesuchas"isooctane",whichbecameanimportantcomponentinaviationfuelblending.Tofurthercomplicatethesituation,asengineperformanceincreased,thealtitudethataircraftcouldreachalsoincreased,whichresultedinconcernsaboutthefuelfreezing.Theaveragetemperaturedecreaseis3.6 °F(2.0 °C)per1,000-foot(300-meter)increaseinaltitude,andat40,000feet(12 km),thetemperaturecanapproach−70 °F(−57 °C).Additiveslikebenzene,withafreezingpointof42 °F(6 °C),wouldfreezeinthegasolineandplugfuellines.Substitutedaromaticssuchastoluene,xylene,andcumene,combinedwithlimitedbenzene,solvedtheproblem.[45] By1935,thereweresevendifferentaviationgradesbasedonoctanerating,twoArmygrades,fourNavygrades,andthreecommercialgradesincludingtheintroductionof100-octaneaviationgasoline.By1937,theArmyestablished100-octaneasthestandardfuelforcombataircraft,andtoaddtotheconfusion,thegovernmentnowrecognized14differentgrades,inadditionto11othersinforeigncountries.Withsomecompaniesrequiredtostock14gradesofaviationfuel,noneofwhichcouldbeinterchanged,theeffectontherefinerswasnegative.Therefiningindustrycouldnotconcentrateonlargecapacityconversionprocessesforsomanydifferentgradesandasolutionhadtobefound.By1941,principallythroughtheeffortsoftheCooperativeFuelResearchCommittee,thenumberofgradesforaviationfuelswasreducedtothree:73,91,and100octane.[46] Thedevelopmentof100-octaneaviationgasolineonaneconomicscalewasdueinparttoJimmyDoolittle,whohadbecomeAviationManagerofShellOilCompany.HeconvincedShelltoinvestinrefiningcapacitytoproduce100-octaneonascalethatnobodyneededsincenoaircraftexistedthatrequiredafuelthatnobodymade.Somefellowemployeeswouldcallhiseffort"Doolittle'smillion-dollarblunder"buttimewouldproveDoolittlecorrect.Beforethis,theArmyhadconsidered100-octanetestsusingpureoctanebutat$25agallon,thepricepreventedthisfromhappening.In1929StanavoSpecificationBoard,Inc.wasorganizedbytheStandardOilcompaniesofCalifornia,Indiana,andNewJerseytoimproveaviationfuelsandoilsandby1935hadplacedtheirfirst100octanefuelonthemarket,StanavoEthylGasoline100.ItwasusedbytheArmy,enginemanufacturersandairlinesfortestingandforairracingandrecordflights.[47]By1936testsatWrightFieldusingthenew,cheaperalternativestopureoctaneprovedthevalueof100octanefuel,andbothShellandStandardOilwouldwinthecontracttosupplytestquantitiesfortheArmy.By1938thepricewasdownto17.5centsagallon,only2.5centsmorethan87octanefuel.BytheendofWWIIthepricewouldbedownto16centsagallon.[48] In1937,EugeneHoudrydevelopedtheHoudryprocessofcatalyticcracking,whichproducedahigh-octanebasestockofgasolinewhichwassuperiortothethermallycrackedproductsinceitdidnotcontainthehighconcentrationofolefins.[28]In1940,therewereonly14HoudryunitsinoperationintheU.S.;by1943,thishadincreasedto77,eitheroftheHoudryprocessoroftheThermoforCatalyticorFluidCatalysttype.[49] Thesearchforfuelswithoctaneratingsabove100ledtotheextensionofthescalebycomparingpoweroutput.Afueldesignatedgrade130wouldproduce130percentasmuchpowerinanengineasitwouldrunningonpureiso-octane.DuringWWII,fuelsabove100-octaneweregiventworatings,arichandaleanmixture,andthesewouldbecalled'performancenumbers'(PN).100-octaneaviationgasolinewouldbereferredtoas130/100grade.[50] WorldWarII[edit] Germany[edit] Oilanditsbyproducts,especiallyhigh-octaneaviationgasoline,wouldprovetobeadrivingconcernforhowGermanyconductedthewar.AsaresultofthelessonsofWorldWarI,GermanyhadstockpiledoilandgasolineforitsblitzkriegoffensiveandhadannexedAustria,adding18,000barrelsperdayofoilproduction,butthiswasnotsufficienttosustaintheplannedconquestofEurope.Becausecapturedsuppliesandoilfieldswouldbenecessarytofuelthecampaign,theGermanhighcommandcreatedaspecialsquadofoil-fieldexpertsdrawnfromtheranksofdomesticoilindustries.Theyweresentintoputoutoil-fieldfiresandgetproductiongoingagainassoonaspossible.Butcapturingoilfieldsremainedanobstaclethroughoutthewar.DuringtheInvasionofPoland,Germanestimatesofgasolineconsumptionturnedouttobevastlytoolow.HeinzGuderianandhisPanzerdivisionsconsumednearly1USgallonpermile(2.4 l/km)ofgasolineonthedrivetoVienna.Whentheywereengagedincombatacrossopencountry,gasolineconsumptionalmostdoubled.Ontheseconddayofbattle,aunitoftheXIXCorpswasforcedtohaltwhenitranoutofgasoline.[51]OneofthemajorobjectivesofthePolishinvasionwastheiroilfieldsbuttheSovietsinvadedandcaptured70percentofthePolishproductionbeforetheGermanscouldreachit.ThroughtheGerman-SovietCommercialAgreement(1940),StalinagreedinvaguetermstosupplyGermanywithadditionaloilequaltothatproducedbynowSoviet-occupiedPolishoilfieldsatDrohobychandBoryslavinexchangeforhardcoalandsteeltubing. EvenaftertheNazisconqueredthevastterritoriesofEurope,thisdidnothelpthegasolineshortage.Thisareahadneverbeenself-sufficientinoilbeforethewar.In1938,theareathatwouldbecomeNazi-occupiedproduced575,000barrelsperday.In1940,totalproductionunderGermancontrolamountedtoonly234,550barrels(37,290 m3).[52]Bythespringof1941andthedepletionofGermangasolinereserves,AdolfHitlersawtheinvasionofRussiatoseizethePolishoilfieldsandtheRussianoilintheCaucasusasthesolutiontotheGermangasolineshortage.AsearlyasJuly1941,followingthe22JunestartofOperationBarbarossa,certainLuftwaffesquadronswereforcedtocurtailgroundsupportmissionsduetoshortagesofaviationgasoline.On9October,theGermanquartermastergeneralestimatedthatarmyvehicleswere24,000barrels(3,800 m3)shortofgasolinerequirements.[53] VirtuallyallofGermany'saviationgasolinecamefromsyntheticoilplantsthathydrogenatedcoalsandcoaltars.Theseprocesseshadbeendevelopedduringthe1930sasanefforttoachievefuelindependence.ThereweretwogradesofaviationgasolineproducedinvolumeinGermany,theB-4orbluegradeandtheC-3orgreengrade,whichaccountedforabouttwo-thirdsofallproduction.B-4wasequivalentto89-octaneandtheC-3wasroughlyequaltotheU.S.100-octane,thoughleanmixturewasratedaround95-octaneandwaspoorerthantheU.S.version.Maximumoutputachievedin1943reached52,200barrelsadaybeforetheAlliesdecidedtotargetthesyntheticfuelplants.Throughcapturedenemyaircraftandanalysisofthegasolinefoundinthem,boththeAlliesandtheAxispowerswereawareofthequalityoftheaviationgasolinebeingproducedandthispromptedanoctaneracetoachievetheadvantageinaircraftperformance.Laterinthewar,theC-3gradewasimprovedtowhereitwasequivalenttotheU.S.150grade(richmixturerating).[54] Japan[edit] Japan,likeGermany,hadalmostnodomesticoilsupplyandbythelate1930s,producedonly7%ofitsownoilwhileimportingtherest–80%fromtheUnitedStates.AsJapaneseaggressiongrewinChina(USSPanayincident)andnewsreachedtheAmericanpublicofJapanesebombingofciviliancenters,especiallythebombingofChungking,publicopinionbegantosupportaU.S.embargo.AGalluppollinJune1939foundthat72percentoftheAmericanpublicsupportedanembargoonwarmaterialstoJapan.ThisincreasedtensionsbetweentheU.S.andJapan,anditledtotheU.S.placingrestrictionsonexports.InJuly1940,theU.S.issuedaproclamationthatbannedtheexportof87octaneorhigheraviationgasolinetoJapan.ThisbandidnothindertheJapaneseastheiraircraftcouldoperatewithfuelsbelow87octaneandifneededtheycouldaddTELtoincreasetheoctane.Asitturnedout,Japanbought550percentmoresub-87octaneaviationgasolineinthefivemonthsaftertheJuly1940banonhigheroctanesales.[55]ThepossibilityofacompletebanofgasolinefromAmericacreatedfrictionintheJapanesegovernmentastowhatactiontotaketosecuremoresuppliesfromtheDutchEastIndiesanddemandedgreateroilexportsfromtheexiledDutchgovernmentaftertheBattleoftheNetherlands.ThisactionpromptedtheU.S.tomoveitsPacificfleetfromSouthernCaliforniatoPearlHarbortohelpstiffenBritishresolvetostayinIndochina.WiththeJapaneseinvasionofFrenchIndochinainSeptember1940,camegreatconcernsaboutthepossibleJapaneseinvasionoftheDutchIndiestosecuretheiroil.AftertheU.S.bannedallexportsofsteelandironscrap,thenextdayJapansignedtheTripartitePactandthisledWashingtontofearthatacompleteU.S.oilembargowouldprompttheJapanesetoinvadetheDutchEastIndies.On16June1941HaroldIckes,whowasappointedPetroleumCoordinatorforNationalDefense,stoppedashipmentofoilfromPhiladelphiatoJapaninlightoftheoilshortageontheEastcoastduetoincreasedexportstoAllies.HealsotelegrammedalloilsuppliersontheEastcoastnottoshipanyoiltoJapanwithouthispermission.PresidentRooseveltcountermandedIckes'orderstellingIckesthatthe"...IsimplyhavenotgotenoughNavytogoaroundandeverylittleepisodeinthePacificmeansfewershipsintheAtlantic".[56]On25July1941,theU.S.frozeallJapanesefinancialassetsandlicenseswouldberequiredforeachuseofthefrozenfundsincludingoilpurchasesthatcouldproduceaviationgasoline.On28July1941,JapaninvadedsouthernIndochina. ThedebateinsidetheJapanesegovernmentastoitsoilandgasolinesituationwasleadingtoinvasionoftheDutchEastIndiesbutthiswouldmeanwarwiththeU.S.,whosePacificfleetwasathreattotheirflank.ThissituationledtothedecisiontoattacktheU.S.fleetatPearlHarborbeforeproceedingwiththeDutchEastIndiesinvasion.On7December1941,JapanattackedPearlHarbor,andthenextdaytheNetherlandsdeclaredwaronJapan,whichinitiatedtheDutchEastIndiescampaign.ButtheJapanesemissedagoldenopportunityatPearlHarbor."AlloftheoilforthefleetwasinsurfacetanksatthetimeofPearlHarbor,"AdmiralChesterNimitz,whobecameCommanderinChiefofthePacificFleet,waslatertosay."Wehadabout4+1⁄2 millionbarrels[720,000 m3]ofoiloutthereandallofitwasvulnerableto.50caliberbullets.HadtheJapanesedestroyedtheoil,"headded,"itwouldhaveprolongedthewaranothertwoyears."[57] UnitedStates[edit] Earlyin1944,WilliamBoyd,presidentoftheAmericanPetroleumInstituteandchairmanofthePetroleumIndustryWarCouncilsaid:"TheAlliesmayhavefloatedtovictoryonawaveofoilinWorldWarI,butinthisinfinitelygreaterWorldWarII,weareflyingtovictoryonthewingsofpetroleum".InDecember1941theUnitedStateshad385,000oilwellsproducing1.4billionbarrelsofoilayearand100-octaneaviationgasolinecapacitywasat40,000barrelsaday.By1944,theU.S.wasproducingover1.5billionbarrelsayear(67percentofworldproduction)andthepetroleumindustryhadbuilt122newplantsfortheproductionof100-octaneaviationgasolineandcapacitywasover400,000barrelsaday–anincreaseofmorethanten-fold.ItwasestimatedthattheU.S.wasproducingenough100-octaneaviationgasolinetopermitthedroppingof20,000shorttons(18,000metrictons)ofbombsontheenemyeverydayoftheyear.TherecordofgasolineconsumptionbytheArmypriortoJune1943wasuncoordinatedaseachsupplyserviceoftheArmypurchaseditsownpetroleumproductsandnocentralizedsystemofcontrolnorrecordsexisted.On1June1943theArmycreatedtheFuelsandLubricantsDivisionoftheQuartermasterCorps,andfromtheirrecordstheytabulatedthattheArmy(excludingfuelsandlubricantsforaircraft)purchasedover2.4billiongallonsofgasolinefordeliverytooverseastheatersbetween1June1943,throughAugust1945.ThatfiguredoesnotincludegasolineusedbytheArmyinsidetheUnitedStates.[58]Motorfuelproductionhaddeclinedfrom701,000,000barrelsin1941downto608,000,000barrelsin1943.[59]WorldWarIImarkedthefirsttimeinU.S.historythatgasolinewasrationedandthegovernmentimposedpricecontrolstopreventinflation.Gasolineconsumptionperautomobiledeclinedfrom755gallonsperyearin1941downto540gallonsin1943,withthegoalofpreservingrubberfortiressincetheJapanesehadcuttheU.S.offfromover90percentofitsrubbersupplywhichhadcomefromtheDutchEastIndiesandtheU.S.syntheticrubberindustrywasinitsinfancy.Averagegasolinepriceswentfromarecordlowof$0.1275pergallon($0.1841withtaxes)in1940to$0.1448pergallon($0.2050withtaxes)in1945.[60] Evenwiththeworld'slargestaviationgasolineproduction,theU.S.militarystillfoundthatmorewasneeded.Throughoutthedurationofthewar,aviationgasolinesupplywasalwaysbehindrequirementsandthisimpactedtrainingandoperations.Thereasonforthisshortagedevelopedbeforethewarevenbegan.Thefreemarketdidnotsupporttheexpenseofproducing100-octaneaviationfuelinlargevolume,especiallyduringtheGreatDepression.Iso-octaneintheearlydevelopmentstagecost$30agallonandevenby1934,itwasstill$2agalloncomparedto$0.18formotorgasolinewhentheArmydecidedtoexperimentwith100-octaneforitscombataircraft.Thoughonly3percentofU.S.combataircraftin1935couldtakefulladvantageofthehigheroctaneduetolowcompressionratios,theArmysawthattheneedforincreasingperformancewarrantedtheexpenseandpurchased100,000gallons.By1937theArmyestablished100-octaneasthestandardfuelforcombataircraftandby1939productionwasonly20,000barrelsaday.Ineffect,theU.S.militarywastheonlymarketfor100-octaneaviationgasolineandaswarbrokeoutinEuropethiscreatedasupplyproblemthatpersistedthroughouttheduration.[61][62] WiththewarinEuropearealityin1939,allpredictionsof100-octaneconsumptionwereoutrunningallpossibleproduction.NeithertheArmynortheNavycouldcontractmorethansixmonthsinadvanceforfuelandtheycouldnotsupplythefundsforplantexpansion.Withoutalong-termguaranteedmarket,thepetroleumindustrywouldnotriskitscapitaltoexpandproductionforaproductthatonlythegovernmentwouldbuy.Thesolutiontotheexpansionofstorage,transportation,finances,andproductionwasthecreationoftheDefenseSuppliesCorporationon19September1940.TheDefenseSuppliesCorporationwouldbuy,transportandstoreallaviationgasolinefortheArmyandNavyatcostplusacarryingfee.[63] WhentheAlliedbreakoutafterD-Dayfoundtheirarmiesstretchingtheirsupplylinestoadangerouspoint,themakeshiftsolutionwastheRedBallExpress.Buteventhissoonwasinadequate.Thetrucksintheconvoyshadtodrivelongerdistancesasthearmiesadvancedandtheywereconsumingagreaterpercentageofthesamegasolinetheyweretryingtodeliver.In1944,GeneralGeorgePatton'sThirdArmyfinallystalledjustshortoftheGermanborderafterrunningoutofgasoline.Thegeneralwassoupsetatthearrivalofatruckloadofrationsinsteadofgasolinehewasreportedtohaveshouted:"Hell,theysendusfood,whentheyknowwecanfightwithoutfoodbutnotwithoutoil."[64]Thesolutionhadtowaitfortherepairingoftherailroadlinesandbridgessothatthemoreefficienttrainscouldreplacethegasoline-consumingtruckconvoys. UnitedStates,1946topresent[edit] Thedevelopmentofjetenginesburningkerosene-basedfuelsduringWWIIforaircraftproducedasuperiorperformingpropulsionsystemthaninternalcombustionenginescouldofferandtheU.S.militaryforcesgraduallyreplacedtheirpistoncombataircraftwithjetpoweredplanes.Thisdevelopmentwouldessentiallyremovethemilitaryneedforeverincreasingoctanefuelsandeliminatedgovernmentsupportfortherefiningindustrytopursuetheresearchandproductionofsuchexoticandexpensivefuels.Commercialaviationwasslowertoadapttojetpropulsionanduntil1958,whentheBoeing707firstenteredcommercialservice,pistonpoweredairlinersstillreliedonaviationgasoline.Butcommercialaviationhadgreatereconomicconcernsthanthemaximumperformancethatthemilitarycouldafford.Asoctanenumbersincreasedsodidthecostofgasolinebuttheincrementalincreaseinefficiencybecomeslessascompressionratiogoesup.Thisrealitysetapracticallimittohowhighcompressionratioscouldincreaserelativetohowexpensivethegasolinewouldbecome.[65]Lastproducedin1955,thePratt&WhitneyR-4360WaspMajorwasusing115/145Aviationgasolineandproducing1horsepowerpercubicinchat6.7compressionratio(turbo-superchargingwouldincreasethis)and1poundofengineweighttoproduce1.1horsepower.ThiscomparestotheWrightBrothersengineneedingalmost17poundsofengineweighttoproduce1horsepower. TheUSautomobileindustryafterWWIIcouldnottakeadvantageofthehighoctanefuelsthenavailable.Automobilecompressionratiosincreasedfromanaverageof5.3-to-1in1931tojust6.7-to-1in1946.Theaverageoctanenumberofregular-grademotorgasolineincreasedfrom58to70duringthesametime.Militaryaircraftwereusingexpensiveturbo-superchargedenginesthatcostatleast10timesasmuchperhorsepowerasautomobileenginesandhadtobeoverhauledevery700to1,000hours.Theautomobilemarketcouldnotsupportsuchexpensiveengines.[66]Itwouldnotbeuntil1957thatthefirstUSautomobilemanufacturercouldmass-produceanenginethatwouldproduceonehorsepowerpercubicinch,theChevrolet283 hp/283cubicinchV-8engineoptionintheCorvette.At$485thiswasanexpensiveoptionthatfewconsumerscouldaffordandwouldonlyappealtotheperformance-orientedconsumermarketwillingtopayforthepremiumfuelrequired.[67]Thisenginehadanadvertisedcompressionratioof10.5-to-1andthe1958AMASpecificationsstatedthattheoctanerequirementwas96-100RON.[68]At535pounds(243 kg)(1959withaluminumintake),ittook1.9pounds(0.86 kg)ofengineweighttomake1horsepower(0.75 kW).[69] Inthe1950soilrefineriesstartedtofocusonhighoctanefuels,andthendetergentswereaddedtogasolinetocleanthejetsincarburetors.The1970switnessedgreaterattentiontotheenvironmentalconsequencesofburninggasoline.TheseconsiderationsledtothephasingoutofTELanditsreplacementbyotherantiknockcompounds.Subsequently,low-sulfurgasolinewasintroduced,inparttopreservethecatalystsinmodernexhaustsystems.[70] Chemicalanalysisandproduction[edit] Someofthecomponentsofgasoline:isooctane,butane,3-ethyltoluene,andtheoctaneenhancerMTBE ApumpjackintheUnitedStates AnoilrigintheGulfofMexico Commercialgasolineisamixtureofalargenumberofdifferenthydrocarbons.Gasolineisproducedtomeetahostofengineperformancespecificationsandmanydifferentcompositionsarepossible.Hence,theexactchemicalcompositionofgasolineisundefined.Theperformancespecificationalsovarieswithseason,requiringmorevolatileblends(duetoaddedbutane)duringwinter,inordertobeabletostartacoldengine.Attherefinery,thecompositionvariesaccordingtothecrudeoilsfromwhichitisproduced,thetypeofprocessingunitspresentattherefinery,howthoseunitsareoperated,andwhichhydrocarbonstreams(blendstocks)therefineryoptstousewhenblendingthefinalproduct.[71] Gasolineisproducedinoilrefineries.Roughly72litres(19 US gal)ofgasolineisderivedfroma160-litre(42 US gal)barrelofcrudeoil.[72]Materialseparatedfromcrudeoilviadistillation,calledvirginorstraight-rungasoline,doesnotmeetspecificationsformodernengines(particularlytheoctanerating;seebelow),butcanbepooledtothegasolineblend. Thebulkofatypicalgasolineconsistsofahomogeneousmixtureofsmall,relativelylightweighthydrocarbonswithbetween4and12carbonatomspermolecule(commonlyreferredtoasC4–C12).[70]Itisamixtureofparaffins(alkanes),olefins(alkenes),andcycloalkanes(naphthenes).Theusageofthetermsparaffinandolefininplaceofthestandardchemicalnomenclaturealkaneandalkene,respectively,isparticulartotheoilindustry.Theactualratioofmoleculesinanygasolinedependsupon: theoilrefinerythatmakesthegasoline,asnotallrefinerieshavethesamesetofprocessingunits; thecrudeoilfeedusedbytherefinery; thegradeofgasoline(inparticular,theoctanerating). Thevariousrefinerystreamsblendedtomakegasolinehavedifferentcharacteristics.Someimportantstreamsincludethefollowing: Straight-rungasoline,commonlyreferredtoasnaphtha,isdistilleddirectlyfromcrudeoil.Oncetheleadingsourceoffuel,itslowoctaneratingrequiredleadadditives.Itislowinaromatics(dependingonthegradeofthecrudeoilstream)andcontainssomecycloalkanes(naphthenes)andnoolefins(alkenes).Between0and20percentofthisstreamispooledintothefinishedgasolinebecausethequantityofthisfractioninthecrudeislessthanfueldemandandthefraction'sResearchOctaneNumber(RON)istoolow.Thechemicalproperties(namelyRONandReidvaporpressure(RVP))ofthestraight-rungasolinecanbeimprovedthroughreformingandisomerization.However,beforefeedingthoseunits,thenaphthaneedstobesplitintolightandheavynaphtha.Straight-rungasolinecanalsobeusedasafeedstockforsteam-crackerstoproduceolefins. Reformate,producedinacatalyticreformer,hasahighoctaneratingwithhigharomaticcontentandrelativelylowolefincontent.Mostofthebenzene,toluene,andxylene(theso-calledBTXhydrocarbons)aremorevaluableaschemicalfeedstocksandarethusremovedtosomeextent. Catalyticcrackedgasoline,orcatalyticcrackednaphtha,producedwithacatalyticcracker,hasamoderateoctanerating,higholefincontent,andmoderatearomaticcontent. Hydrocrackate(heavy,mid,andlight),producedwithahydrocracker,hasamediumtolowoctaneratingandmoderatearomaticlevels. Alkylateisproducedinanalkylationunit,usingisobutaneandolefinsasfeedstocks.FinishedalkylatecontainsnoaromaticsorolefinsandhasahighMON(MotorOctaneNumber). Isomerateisobtainedbyisomerizinglow-octanestraight-rungasolineintoiso-paraffins(non-chainalkanes,suchasisooctane).IsomeratehasamediumRONandMON,butnoaromaticsorolefins. Butaneisusuallyblendedinthegasolinepool,althoughthequantityofthisstreamislimitedbytheRVPspecification. Thetermsabovearethejargonusedintheoilindustry,andtheterminologyvaries. Currently,manycountriessetlimitsongasolinearomaticsingeneral,benzeneinparticular,andolefin(alkene)content.Suchregulationshaveledtoanincreasingpreferenceforalkaneisomers,suchasisomerateoralkylate,astheiroctaneratingishigherthann-alkanes.IntheEuropeanUnion,thebenzenelimitissetat1%byvolumeforallgradesofautomotivegasoline.ThisisusuallyachievedbyavoidingfeedingC6,inparticularcyclohexane,tothereformerunit,whereitwouldbeconvertedtobenzene.Therefore,only(desulfurized)heavyvirginnaphtha(HVN)isfedtothereformerunit[71] Gasolinecanalsocontainotherorganiccompounds,suchasorganicethers(deliberatelyadded),plussmalllevelsofcontaminants,inparticularorganosulfurcompounds(whichareusuallyremovedattherefinery). Physicalproperties[edit] AShellstationinHiroshima,Japan Density[edit] Thespecificgravityofgasolinerangesfrom0.71to0.77,[73]withhigherdensitieshavingagreatervolumefractionofaromatics.[74]Finishedmarketablegasolineistraded(inEurope)withastandardreferenceof0.755 kg/L(6.30 lb/US gal),anditspriceisescalatedorde-escalatedaccordingtoitsactualdensity.[clarificationneeded]Becauseofitslowdensity,gasolinefloatsonwater,andthereforewatercannotgenerallybeusedtoextinguishagasolinefireunlessappliedinafinemist. Stability[edit] Qualitygasolineshouldbestableforsixmonthsifstoredproperly,butasgasolineisamixtureratherthanasinglecompound,itwillbreakdownslowlyovertimeduetotheseparationofthecomponents.Gasolinestoredforayearwillmostlikelybeabletobeburnedinaninternalcombustionenginewithouttoomuchtrouble.However,theeffectsoflong-termstoragewillbecomemorenoticeablewitheachpassingmonthuntilatimecomeswhenthegasolineshouldbedilutedwithever-increasingamountsoffreshlymadefuelsothattheoldergasolinemaybeusedup.Ifleftundiluted,improperoperationwilloccurandthismayincludeenginedamagefrommisfiringorthelackofproperactionofthefuelwithinafuelinjectionsystemandfromanonboardcomputerattemptingtocompensate(ifapplicabletothevehicle).Gasolineshouldideallybestoredinanairtightcontainer(topreventoxidationorwatervapormixinginwiththegas)thatcanwithstandthevaporpressureofthegasolinewithoutventing(topreventthelossofthemorevolatilefractions)atastablecooltemperature(toreducetheexcesspressurefromliquidexpansionandtoreducetherateofanydecompositionreactions).Whengasolineisnotstoredcorrectly,gumsandsolidsmayresult,whichcancorrodesystemcomponentsandaccumulateonwetsurfaces,resultinginaconditioncalled"stalefuel".Gasolinecontainingethanolisespeciallysubjecttoabsorbingatmosphericmoisture,thenforminggums,solids,ortwophases(ahydrocarbonphasefloatingontopofawater-alcoholphase). Thepresenceofthesedegradationproductsinthefueltankorfuellinesplusacarburetororfuelinjectioncomponentsmakesithardertostarttheengineorcausesreducedengineperformance.Onresumptionofregularengineuse,thebuildupmayormaynotbeeventuallycleanedoutbytheflowoffreshgasoline.Theadditionofafuelstabilizertogasolinecanextendthelifeoffuelthatisnotorcannotbestoredproperly,thoughremovalofallfuelfromafuelsystemistheonlyrealsolutiontotheproblemoflong-termstorageofanengineoramachineorvehicle.Typicalfuelstabilizersareproprietarymixturescontainingmineralspirits,isopropylalcohol,1,2,4-trimethylbenzeneorotheradditives.Fuelstabilizersarecommonlyusedforsmallengines,suchaslawnmowerandtractorengines,especiallywhentheiruseissporadicorseasonal(littletonouseforoneormoreseasonsoftheyear).Usershavebeenadvisedtokeepgasolinecontainersmorethanhalffullandproperlycappedtoreduceairexposure,toavoidstorageathightemperatures,torunanenginefortenminutestocirculatethestabilizerthroughallcomponentspriortostorage,andtoruntheengineatintervalstopurgestalefuelfromthecarburetor.[70] GasolinestabilityrequirementsaresetbythestandardASTMD4814.Thisstandarddescribesthevariouscharacteristicsandrequirementsofautomotivefuelsforuseoverawiderangeofoperatingconditionsingroundvehiclesequippedwithspark-ignitionengines. Combustionenergycontent[edit] Agasoline-fueledinternalcombustionengineobtainsenergyfromthecombustionofgasoline'svarioushydrocarbonswithoxygenfromtheambientair,yieldingcarbondioxideandwaterasexhaust.Thecombustionofoctane,arepresentativespecies,performsthechemicalreaction: 2C8H18+25O2→16CO2+18H2O Byweight,combustionofgasolinereleasesabout46.7 MJ/kg(13.0 kWh/kg;21.2 MJ/lb)orbyvolume33.6 MJ/L(9.3 kWh/L;127 MJ/US gal;121,000 Btu/US gal),quotingthelowerheatingvalue.[75]Gasolineblendsdiffer,andthereforeactualenergycontentvariesaccordingtotheseasonandproducerbyupto1.75%moreorlessthantheaverage.[76]Onaverage,about74L(19.5USgal;16.3impgal)ofgasolineareavailablefromabarrelofcrudeoil(about46%byvolume),varyingwiththequalityofthecrudeandthegradeofthegasoline.Theremainderisproductsrangingfromtartonaphtha.[77] Ahigh-octane-ratedfuel,suchasliquefiedpetroleumgas(LPG),hasanoveralllowerpoweroutputatthetypical10:1compressionratioofanenginedesignoptimizedforgasolinefuel.AnenginetunedforLPGfuelviahighercompressionratios(typically12:1)improvesthepoweroutput.Thisisbecausehigher-octanefuelsallowforahighercompressionratiowithoutknocking,resultinginahighercylindertemperature,whichimprovesefficiency.Also,increasedmechanicalefficiencyiscreatedbyahighercompressionratiothroughtheconcomitanthigherexpansionratioonthepowerstroke,whichisbyfarthegreatereffect.Thehigherexpansionratioextractsmoreworkfromthehigh-pressuregascreatedbythecombustionprocess.AnAtkinsoncycleengineusesthetimingofthevalveeventstoproducethebenefitsofahighexpansionratiowithoutthedisadvantages,chieflydetonation,ofahighcompressionratio.Ahighexpansionratioisalsooneofthetwokeyreasonsfortheefficiencyofdieselengines,alongwiththeeliminationofpumpinglossesduetothrottlingoftheintakeairflow. ThelowerenergycontentofLPGbyliquidvolumeincomparisontogasolineisduemainlytoitslowerdensity.Thislowerdensityisapropertyofthelowermolecularweightofpropane(LPG'schiefcomponent)comparedtogasoline'sblendofvarioushydrocarboncompoundswithheaviermolecularweightsthanpropane.Conversely,LPG'senergycontentbyweightishigherthangasoline'sduetoahigherhydrogen-to-carbonratio. MolecularweightsofthespeciesintherepresentativeoctanecombustionareC8H18114,O232,CO244,H2O18;therefore1 kgoffuelreactswith3.51 kgofoxygentoproduce3.09 kgofcarbondioxideand1.42 kgofwater. Octanerating[edit] Mainarticle:Octanerating Spark-ignitionenginesaredesignedtoburngasolineinacontrolledprocesscalleddeflagration.However,theunburnedmixturemayautoignitebypressureandheatalone,ratherthanignitingfromthesparkplugatexactlytherighttime,causingarapidpressurerisethatcandamagetheengine.Thisisoftenreferredtoasengineknockingorend-gasknock.Knockingcanbereducedbyincreasingthegasoline'sresistancetoautoignition,whichisexpressedbyitsoctanerating. Octaneratingismeasuredrelativetoamixtureof2,2,4-trimethylpentane(anisomerofoctane)andn-heptane.Therearedifferentconventionsforexpressingoctaneratings,sothesamephysicalfuelmayhaveseveraldifferentoctaneratingsbasedonthemeasureused.Oneofthebestknownistheresearchoctanenumber(RON). Theoctaneratingoftypicalcommerciallyavailablegasolinevariesbycountry.InFinland,Sweden,andNorway,95RONisthestandardforregularunleadedgasolineand98RONisalsoavailableasamoreexpensiveoption. IntheUnitedKingdom,over95%ofgasolinesoldhas95RONandismarketedasUnleadedorPremiumUnleaded.SuperUnleaded,with97/98RONandbrandedhigh-performancefuels(e.g.ShellV-Power,BPUltimate)with99RONmakeupthebalance.Gasolinewith102RONmayrarelybeavailableforracingpurposes.[78][79][80] IntheUnitedStates,octaneratingsinunleadedfuelsvarybetween85[81]and87AKI(91–92RON)forregular,89–90AKI(94–95RON)formid-grade(equivalenttoEuropeanregular),upto90–94AKI(95–99RON)forpremium(Europeanpremium). 91 92 93 94 95 96 97 98 99 100 101 102 Scandinavian Regular Premium UK Regular Premium Super High-performance USA Regular Mid-grade Premium AsSouthAfrica'slargestcity,Johannesburg,islocatedontheHighveldat1,753meters(5,751 ft)abovesealevel,theAutomobileAssociationofSouthAfricarecommends95-octanegasolineatlowaltitudeand93-octaneforuseinJohannesburgbecause"Thehigherthealtitudethelowertheairpressure,andthelowertheneedforahighoctanefuelasthereisnorealperformancegain".[82] Octaneratingbecameimportantasthemilitarysoughthigheroutputforaircraftenginesinthelate1930sandthe1940s.Ahigheroctaneratingallowsahighercompressionratioorsuperchargerboost,andthushighertemperaturesandpressures,whichtranslatetohigherpoweroutput.Somescientists[who?]evenpredictedthatanationwithagoodsupplyofhigh-octanegasolinewouldhavetheadvantageinairpower.In1943,theRolls-RoyceMerlinaeroengineproduced980 kW(1,320 hp)using100RONfuelfromamodest27 L(7.1 US gal)displacement.BythetimeofOperationOverlord,boththeRAFandUSAAFwereconductingsomeoperationsinEuropeusing150RONfuel(100/150avgas),obtainedbyadding2.5%anilineto100-octaneavgas.[83]BythistimetheRolls-RoyceMerlin66wasdeveloping1,500 kW(2,000 hp)usingthisfuel. Additives[edit] Seealso:Listofgasolineadditives Antiknockadditives[edit] AplasticcontainerforstoringgasolineusedinGermany Agascan Tetraethyllead[edit] Mainarticle:Tetraethyllead Thisarticleorsectionappearstocontradictitself.Pleaseseethetalkpageformoreinformation.(April2022) Gasoline,whenusedinhigh-compressioninternalcombustionengines,tendstoauto-igniteor"detonate"causingdamagingengineknocking(alsocalled"pinging"or"pinking").Toaddressthisproblem,tetraethyllead(TEL)waswidelyadoptedasanadditiveforgasolineinthe1920s.Withagrowingawarenessoftheseriousnessoftheextentofenvironmentalandhealthdamagecausedbyleadcompounds,however,andtheincompatibilityofleadwithcatalyticconverters,governmentsbegantomandatereductionsingasolinelead. IntheUnitedStates,theEnvironmentalProtectionAgencyissuedregulationstoreducetheleadcontentofleadedgasolineoveraseriesofannualphases,scheduledtobeginin1973butdelayedbycourtappealsuntil1976.By1995,leadedfuelaccountedforonly0.6percentoftotalgasolinesalesandunder2,000shorttons(1,800metrictons)ofleadperyear.From1January1996,theU.S.CleanAirActbannedthesaleofleadedfuelforuseinon-roadvehiclesintheU.S.TheuseofTELalsonecessitatedotheradditives,suchasdibromoethane. Europeancountriesbeganreplacinglead-containingadditivesbytheendofthe1980s,andbytheendofthe1990s,leadedgasolinewasbannedwithintheentireEuropeanUnion.TheUAEstartedtoswitchtounleadedintheearly2000s.[84] Reductionintheaverageleadcontentofhumanbloodmaybeamajorcauseforfallingviolentcrimeratesaroundtheworld[85]includingSouthAfrica.[86]Astudyfoundacorrelationbetweenleadedgasolineusageandviolentcrime.[87][88]Otherstudiesfoundnocorrelation.(SeeLead–crimehypothesis) InAugust2021,theUNEnvironmentProgrammeannouncedthatleadedpetrolhadbeeneradicatedworldwide,withAlgeriabeingthelastcountrytodepleteitsreserves.UNSecretary-GeneralAntónioGuterrescalledtheeradicationofleadedpetrolan"internationalsuccessstory".Healsoadded:"Endingtheuseofleadedpetrolwillpreventmorethanonemillionprematuredeathseachyearfromheartdisease,strokesandcancer,anditwillprotectchildrenwhoseIQsaredamagedbyexposuretolead".Greenpeacecalledtheannouncement"theendofonetoxicera".[89]However,leadedgasolinecontinuestobeusedinaeronautic,autoracingandoff-roadapplications.[90]Theuseofleadedadditivesisstillpermittedworldwidefortheformulationofsomegradesofaviationgasolinesuchas100LL,becausetherequiredoctaneratingisdifficulttoreachwithouttheuseofleadedadditives. Differentadditiveshavereplacedleadcompounds.Themostpopularadditivesincludearomatichydrocarbons,ethers(MTBEandETBE),andalcohols,mostcommonlyethanol. Leadreplacementpetrol[edit] Leadreplacementpetrol(LRP)wasdevelopedforvehiclesdesignedtorunonleadedfuelsandincompatiblewithunleadedfuels.Ratherthantetraethyllead,itcontainsothermetalssuchaspotassiumcompoundsormethylcyclopentadienylmanganesetricarbonyl(MMT);thesearepurportedtobuffersoftexhaustvalvesandseatssothattheydonotsufferrecessionduetotheuseofunleadedfuel. LRPwasmarketedduringandafterthephaseoutofleadedmotorfuelsintheUnitedKingdom,Australia,SouthAfrica,andsomeothercountries.[vague]ConsumerconfusionledtoawidespreadmistakenpreferenceforLRPratherthanunleaded,[91]andLRPwasphasedout8to10yearsaftertheintroductionofunleaded.[92] LeadedgasolinewaswithdrawnfromsaleinBritainafter31December1999,sevenyearsafterEECregulationssignaledtheendofproductionforcarsusingleadedgasolineinmemberstates.Atthisstage,alargepercentageofcarsfromthe1980sandearly1990swhichranonleadedgasolinewerestillinuse,alongwithcarsthatcouldrunonunleadedfuel.However,thedecliningnumberofsuchcarsonBritishroadssawmanygasolinestationswithdrawingLRPfromsaleby2003.[93] MMT[edit] Methylcyclopentadienylmanganesetricarbonyl(MMT)isusedinCanadaandtheUStoboostoctanerating.[94]ItsuseintheUnitedStateshasbeenrestrictedbyregulations,althoughitiscurrentlyallowed.[95]ItsuseintheEuropeanUnionisrestrictedbyArticle8aoftheFuelQualityDirective[96]followingitstestingundertheProtocolfortheevaluationofeffectsofmetallicfuel-additivesontheemissionsperformanceofvehicles.[97] Fuelstabilizers(antioxidantsandmetaldeactivators)[edit] Substitutedphenolsandderivativesofphenylenediaminearecommonantioxidantsusedtoinhibitgumformationingasoline Gummy,stickyresindepositsresultfromoxidativedegradationofgasolineduringlong-termstorage.Theseharmfuldepositsarisefromtheoxidationofalkenesandotherminorcomponentsingasoline(seedryingoils).Improvementsinrefinerytechniqueshavegenerallyreducedthesusceptibilityofgasolinestotheseproblems.Previously,catalyticallyorthermallycrackedgasolinesweremostsusceptibletooxidation.Theformationofgumsisacceleratedbycoppersalts,whichcanbeneutralizedbyadditivescalledmetaldeactivators. Thisdegradationcanbepreventedthroughtheadditionof5–100ppmofantioxidants,suchasphenylenediaminesandotheramines.[70]Hydrocarbonswithabrominenumberof10orabovecanbeprotectedwiththecombinationofunhinderedorpartiallyhinderedphenolsandoil-solublestrongaminebases,suchashinderedphenols."Stale"gasolinecanbedetectedbyacolorimetricenzymatictestfororganicperoxidesproducedbyoxidationofthegasoline.[98] Gasolinesarealsotreatedwithmetaldeactivators,whicharecompoundsthatsequester(deactivate)metalsaltsthatotherwiseacceleratetheformationofgummyresidues.Themetalimpuritiesmightarisefromtheengineitselforascontaminantsinthefuel. Detergents[edit] Gasoline,asdeliveredatthepump,alsocontainsadditivestoreduceinternalenginecarbonbuildups,improvecombustionandalloweasierstartingincoldclimates.HighlevelsofdetergentcanbefoundinTopTierDetergentGasolines.ThespecificationforTopTierDetergentGasolineswasdevelopedbyfourautomakers:GM,Honda,Toyota,andBMW.Accordingtothebulletin,theminimalU.S.EPArequirementisnotsufficienttokeepenginesclean.[99]Typicaldetergentsincludealkylaminesandalkylphosphatesatalevelof50–100ppm.[70] Ethanol[edit] Seealso:EthanolfuelandCommonethanolfuelmixtures EuropeanUnion[edit] IntheEU,5%ethanolcanbeaddedwithinthecommongasolinespec(EN228).Discussionsareongoingtoallow10%blendingofethanol(availableinFinnish,FrenchandGermangasstations).InFinland,mostgasolinestationssell95E10,whichis10%ethanol,and98E5,whichis5%ethanol.MostgasolinesoldinSwedenhas5–15%ethanoladded.ThreedifferentethanolblendsaresoldintheNetherlands—E5,E10andhE15.Thelastofthesediffersfromstandardethanol–gasolineblendsinthatitconsistsof15%hydrousethanol(i.e.,theethanol–waterazeotrope)insteadoftheanhydrousethanoltraditionallyusedforblendingwithgasoline. Brazil[edit] TheBrazilianNationalAgencyofPetroleum,NaturalGasandBiofuels(ANP)requiresgasolineforautomobileusetohave27.5%ofethanoladdedtoitscomposition.[100]Purehydratedethanolisalsoavailableasafuel. Australia[edit] Legislationrequiresretailerstolabelfuelscontainingethanolonthedispenser,andlimitsethanoluseto10%ofgasolineinAustralia.SuchgasolineiscommonlycalledE10bymajorbrands,anditischeaperthanregularunleadedgasoline. UnitedStates[edit] ThefederalRenewableFuelStandard(RFS)effectivelyrequiresrefinersandblenderstoblendrenewablebiofuels(mostlyethanol)withgasoline,sufficienttomeetagrowingannualtargetoftotalgallonsblended.Althoughthemandatedoesnotrequireaspecificpercentageofethanol,annualincreasesinthetargetcombinedwithdeclininggasolineconsumptionhavecausedthetypicalethanolcontentingasolinetoapproach10%.Mostfuelpumpsdisplayastickerthatstatesthatthefuelmaycontainupto10%ethanol,anintentionaldisparitythatreflectsthevaryingactualpercentage.Untillate2010,fuelretailerswereonlyauthorizedtosellfuelcontainingupto10percentethanol(E10),andmostvehiclewarranties(exceptforflexiblefuelvehicles)authorizefuelsthatcontainnomorethan10percentethanol.[citationneeded]InpartsoftheUnitedStates,ethanolissometimesaddedtogasolinewithoutanindicationthatitisacomponent. India[edit] InOctober2007,theGovernmentofIndiadecidedtomake5%ethanolblending(withgasoline)mandatory.Currently,10%ethanolblendedproduct(E10)isbeingsoldinvariouspartsofthecountry.[101][102]Ethanolhasbeenfoundinatleastonestudytodamagecatalyticconverters.[103] Dyes[edit] Mainarticle:Fueldyes Thoughgasolineisanaturallycolorlessliquid,manygasolinesaredyedinvariouscolorstoindicatetheircompositionandacceptableuses.InAustralia,thelowestgradeofgasoline(RON91)wasdyedalightshadeofred/orangeandisnowthesamecolorasthemediumgrade(RON95)andhighoctane(RON98),whicharedyedyellow.[104]IntheUnitedStates,aviationgasoline(avgas)isdyedtoidentifyitsoctaneratingandtodistinguishitfromkerosene-basedjetfuel,whichisclear.[105]InCanada,thegasolineformarineandfarmuseisdyedredandisnotsubjecttosalestax.[106] Oxygenateblending[edit] Oxygenateblendingaddsoxygen-bearingcompoundssuchasMTBE,ETBE,TAME,TAEE,ethanol,andbiobutanol.Thepresenceoftheseoxygenatesreducestheamountofcarbonmonoxideandunburnedfuelintheexhaust.InmanyareasthroughouttheU.S.,oxygenateblendingismandatedbyEPAregulationstoreducesmogandotherairbornepollutants.Forexample,inSouthernCaliforniafuelmustcontain2%oxygenbyweight,resultinginamixtureof5.6%ethanolingasoline.Theresultingfuelisoftenknownasreformulatedgasoline(RFG)oroxygenatedgasoline,orinthecaseofCalifornia,Californiareformulatedgasoline.ThefederalrequirementthatRFGcontainoxygenwasdroppedon6May2006becausetheindustryhaddevelopedVOC-controlledRFGthatdidnotneedadditionaloxygen.[107] MTBEwasphasedoutintheU.S.duetogroundwatercontaminationandtheresultingregulationsandlawsuits.Ethanoland,toalesserextent,ethanol-derivedETBEarecommonsubstitutes.Acommonethanol-gasolinemixof10%ethanolmixedwithgasolineiscalledgasoholorE10,andanethanol-gasolinemixof85%ethanolmixedwithgasolineiscalledE85.ThemostextensiveuseofethanoltakesplaceinBrazil,wheretheethanolisderivedfromsugarcane.In2004,over13,000 millionlitres(3.4×10^9 US gal)ofethanolwasproducedintheUnitedStatesforfueluse,mostlyfromcorn,andE85isslowlybecomingavailableinmuchoftheUnitedStates,thoughmanyoftherelativelyfewstationsvendingE85arenotopentothegeneralpublic.[108] Theuseofbioethanolandbio-methanol,eitherdirectlyorindirectlybyconversionofethanoltobio-ETBE,ormethanoltobio-MTBEisencouragedbytheEuropeanUnionDirectiveonthePromotionoftheuseofbiofuelsandotherrenewablefuelsfortransport.Sinceproducingbioethanolfromfermentedsugarsandstarchesinvolvesdistillation,though,ordinarypeopleinmuchofEuropecannotlegallyfermentanddistilltheirownbioethanolatpresent(unlikeintheU.S.,wheregettingaBATFdistillationpermithasbeeneasysincethe1973oilcrisis). Safety[edit] HAZMATclass3gasoline Toxicity[edit] Thesafetydatasheetfora2003Texanunleadedgasolineshowsatleast15hazardouschemicalsoccurringinvariousamounts,includingbenzene(upto5%byvolume),toluene(upto35%byvolume),naphthalene(upto1%byvolume),trimethylbenzene(upto7%byvolume),methyltert-butylether(MTBE)(upto18%byvolume,insomestates)andabouttenothers.[109]Hydrocarbonsingasolinegenerallyexhibitlowacutetoxicities,withLD50of700–2700 mg/kgforsimplearomaticcompounds.[110]Benzeneandmanyantiknockingadditivesarecarcinogenic. Peoplecanbeexposedtogasolineintheworkplacebyswallowingit,breathinginvapors,skincontact,andeyecontact.Gasolineistoxic.TheNationalInstituteforOccupationalSafetyandHealth(NIOSH)hasalsodesignatedgasolineasacarcinogen.[111]Physicalcontact,ingestion,orinhalationcancausehealthproblems.Sinceingestinglargeamountsofgasolinecancausepermanentdamagetomajororgans,acalltoalocalpoisoncontrolcenteroremergencyroomvisitisindicated.[112] Contrarytocommonmisconception,swallowinggasolinedoesnotgenerallyrequirespecialemergencytreatment,andinducingvomitingdoesnothelp,andcanmakeitworse.AccordingtopoisonspecialistBradDahl,"eventwomouthfulswouldn'tbethatdangerousaslongasitgoesdowntoyourstomachandstaysthereorkeepsgoing."TheUSCDC'sAgencyforToxicSubstancesandDiseaseRegistrysaysnottoinducevomiting,lavage,oradministeractivatedcharcoal.[113][114] Inhalationforintoxication[edit] Inhaled(huffed)gasolinevaporisacommonintoxicant.Usersconcentrateandinhalegasolinevapourinamannernotintendedbythemanufacturertoproduceeuphoriaandintoxication.GasolineinhalationhasbecomeepidemicinsomepoorercommunitiesandindigenousgroupsinAustralia,Canada,NewZealand,andsomePacificIslands.[115]Thepracticeisthoughttocausesevereorgandamage,alongwithothereffectssuchasintellectualdisabilityandvariouscancers.[116][117][118][119] InCanada,NativechildrenintheisolatedNorthernLabradorcommunityofDavisInletwerethefocusofnationalconcernin1993,whenmanywerefoundtobesniffinggasoline.TheCanadianandprovincialNewfoundlandandLabradorgovernmentsintervenedonseveraloccasions,sendingmanychildrenawayfortreatment.DespitebeingmovedtothenewcommunityofNatuashishin2002,seriousinhalantabuseproblemshavecontinued.SimilarproblemswerereportedinSheshatshiuin2000andalsoinPikangikumFirstNation.[120]In2012,theissueonceagainmadethenewsmediainCanada.[121] Seealso:IndigenousAustralian§ Substanceabuse Australiahaslongfacedapetrol(gasoline)sniffingprobleminisolatedandimpoverishedaboriginalcommunities.AlthoughsomesourcesarguethatsniffingwasintroducedbyUnitedStatesservicemenstationedinthenation'sTopEndduringWorldWarII[122]orthroughexperimentationby1940s-eraCobourgPeninsulasawmillworkers,[123]othersourcesclaimthatinhalantabuse(suchasglueinhalation)emergedinAustraliainthelate1960s.[124]Chronic,heavypetrolsniffingappearstooccuramongremote,impoverishedindigenouscommunities,wherethereadyaccessibilityofpetrolhashelpedtomakeitacommonsubstanceforabuse. InAustralia,petrolsniffingnow[citationneeded]occurswidelythroughoutremoteAboriginalcommunitiesintheNorthernTerritory,WesternAustralia,northernpartsofSouthAustralia,andQueensland.Thenumberofpeoplesniffingpetrolgoesupanddownovertimeasyoungpeopleexperimentorsniffoccasionally."Boss",orchronic,sniffersmaymoveinandoutofcommunities;theyareoftenresponsibleforencouragingyoungpeopletotakeitup.[125]In2005,theGovernmentofAustraliaandBPAustraliabegantheusageofOpalfuelinremoteareaspronetopetrolsniffing.[126]Opalisanon-sniffablefuel(whichismuchlesslikelytocauseahigh)andhasmadeadifferenceinsomeindigenouscommunities. Flammability[edit] Uncontrolledburningofgasolineproduceslargequantitiesofsootandcarbonmonoxide. Gasolineisextremelyflammableduetoitslowflashpointof-23°C(-9.4°F).Likeotherhydrocarbons,gasolineburnsinalimitedrangeofitsvaporphaseand,coupledwithitsvolatility,thismakesleakshighlydangerouswhensourcesofignitionarepresent.Gasolinehasalowerexplosivelimitof1.4%byvolumeandanupperexplosivelimitof7.6%.Iftheconcentrationisbelow1.4%,theair-gasolinemixtureistooleananddoesnotignite.Iftheconcentrationisabove7.6%,themixtureistoorichandalsodoesnotignite.However,gasolinevaporrapidlymixesandspreadswithair,makingunconstrainedgasolinequicklyflammable. Gasolineexhaust[edit] Theexhaustgasgeneratedbyburninggasolinenotonlydoesseriousharmtotheenvironmentbutalsotopeople'shealth.AfterCOisinhaledintothehumanbody,itisveryeasytocombinewithhemoglobinintheblood,anditsaffinityis300timesthatofoxygen.Therefore,thehemoglobininthelungsdoesnotcombinewithoxygenbutwithCO,causingthehumanbodytobehypoxic,causingheadaches,dizziness,vomiting,andotherpoisoningsymptoms.Inseverecases,itmayleadtodeath.[127][128]Hydrocarbonsonlyaffectthehumanbodywhentheirconcentrationisquitehigh,andtheirtoxicityleveldependsonthechemicalcomposition.Thehydrocarbonsproducedbyincompletecombustionincludealkanes,aromatics,andaldehydes.Amongthem,aconcentrationofmethaneandethaneover35g/m3willcauselossofconsciousnessorsuffocation,aconcentrationofpentaneandhexaneover45g/m3willhaveananestheticeffect,andaromatichydrocarbonswillhavemoreseriouseffectsonhealth,bloodtoxicity,neurotoxicity,andcancer.Iftheconcentrationofbenzeneexceeds40ppm,itcancauseleukemia,andxylenecancauseheadache,dizziness,nausea,andvomiting.Humanexposuretolargeamountsofaldehydescancauseeyeirritation,nausea,anddizziness.Inadditiontocarcinogeniceffects,long-termexposurecancausedamagetotheskin,liver,kidneys,andcataracts.[129]AfterNOxentersthealveoli,ithasaseverestimulatingeffectonthelungtissue.Itcanirritatetheconjunctivaoftheeyes,causetearingandcausepinkeyes.Italsohasastimulatingeffectonthenose,pharynx,throat,andotherorgans.Itcancauseacutewheezing,breathingdifficulties,redeyes,sorethroat,anddizzinesscausingpoisoning.[129][130] Environmentalimpact[edit] Inrecentyears,withtherapiddevelopmentofthemotorvehicleeconomy,theproductionanduseofmotorvehicleshaveincreaseddramatically,andthepollutionbymotorvehicleexhausttotheenvironmenthasbecomemoreandmoreserious.Theairpollutioninmanylargecitieshaschangedfromcoal-burningpollutionto"motorvehiclepollution."IntheUnitedStates,transportationisthelargestsourceofcarbonemissions,accountingfor30%ofthetotalcarbonfootprintoftheUnitedStates.[131]Combustionofgasolineproduces2.35 kg/l(19.6 lb/US gal)ofcarbondioxide,agreenhousegas.[132][133] Unburntgasolineandevaporationfromthetank,whenintheatmosphere,reactinsunlighttoproducephotochemicalsmog.Vaporpressureinitiallyriseswithsomeadditionofethanoltogasoline,buttheincreaseisgreatestat10%byvolume.[134]Athigherconcentrationsofethanolabove10%,thevaporpressureoftheblendstartstodecrease.Ata10%ethanolbyvolume,theriseinvaporpressuremaypotentiallyincreasetheproblemofphotochemicalsmog.Thisriseinvaporpressurecouldbemitigatedbyincreasingordecreasingthepercentageofethanolinthegasolinemixture.Thechiefrisksofsuchleakscomenotfromvehicles,butgasolinedeliverytruckaccidentsandleaksfromstoragetanks.Becauseofthisrisk,most(underground)storagetanksnowhaveextensivemeasuresinplacetodetectandpreventanysuchleaks,suchasmonitoringsystems(Veeder-Root,FranklinFueling). Productionofgasolineconsumes1.5 dm3/km(0.63 US gal/mi)ofwaterbydrivendistance.[135] Gasolineusecausesavarietyofdeleteriouseffectstothehumanpopulationandtotheclimategenerally.Theharmsimposedincludeahigherrateofprematuredeathandailments,suchasasthma,causedbyairpollution,higherhealthcarecostsforthepublicgenerally,decreasedcropyields,missedworkandschooldaysduetoillness,increasedfloodingandotherextremeweathereventslinkedtoglobalclimatechange,andothersocialcosts.Thecostsimposedonsocietyandtheplanetareestimatedtobe$3.80pergallonofgasoline,inadditiontothepricepaidatthepumpbytheuser.Thedamagetothehealthandclimatecausedbyagasoline-poweredvehiclegreatlyexceedsthatcausedbyelectricvehicles.[136][137] Carbondioxide[edit] About2.353 kg/l(19.64 lb/US gal)ofcarbondioxide(CO2)areproducedfromburninggasolinethatdoesnotcontainethanol.About2.682 kg/l(22.38 lb/US gal)ofCO2areproducedfromburningdieselfuel.[133] TheU.S.EIAestimatesthatU.S.motorgasolineanddiesel(distillate)fuelconsumptionfortransportationin2015resultedintheemissionofabout1,105milliontonsofCO2and440milliontonsofCO2,respectively,foratotalof1,545milliontonsofCO2.[133]Thistotalwasequivalentto83%oftotalU.S.transportation-sectorCO2emissionsandequivalentto29%oftotalU.S.energy-relatedCO2emissionsin2015.[133] MostoftheretailgasolinenowsoldintheUnitedStatescontainsabout10%fuelethanol(orE10)byvolume.[133]BurningE10producesabout2.119 kg/l(17.68 lb/US gal)ofCO2thatisemittedfromthefossilfuelcontent.IftheCO2emissionsfromethanolcombustionareconsidered,thenabout2.271 kg/l(18.95 lb/US gal)ofCO2areproducedwhenE10iscombusted.[133]About1.525 kg/l(12.73 lb/US gal)ofCO2areproducedwhenpureethanoliscombusted.[133] Contaminationofsoilandwater[edit] Gasolineenterstheenvironmentthroughthesoil,groundwater,surfacewater,andair.Therefore,humansmaybeexposedtogasolinethroughmethodssuchasbreathing,eating,andskincontact.Forexample,usinggasoline-filledequipment,suchaslawnmowers,drinkinggasoline-contaminatedwaterclosetogasolinespillsorleakstothesoil,workingatagasstation,inhalinggasolinevolatilegaswhenrefuelingatagasstationistheeasiestwaytobeexposedtogasoline.[138] Useandpricing[edit] Mainarticles:GasolineanddieselusageandpricingandPeakoil Europe[edit] CountriesinEuropeimposesubstantiallyhighertaxesonfuelssuchasgasolinewhencomparedtotheUnitedStates.ThepriceofgasolineinEuropeistypicallyhigherthanthatintheU.S.duetothisdifference.[139] UnitedStates[edit] Thissectionneedstobeupdated.Pleasehelpupdatethisarticletoreflectrecenteventsornewlyavailableinformation.(April2016) USRegularGasolinePricesthrough2018,inUSdollars From1998to2004,thepriceofgasolinefluctuatedbetweenUS$1andUS$2perU.S.gallon.[140]After2004,thepriceincreaseduntiltheaveragegaspricereachedahighof$4.11perU.S.galloninmid-2008,butrecededtoapproximately$2.60perU.S.gallonbySeptember2009.[140]TheU.S.experiencedanupswingingasolinepricesthrough2011,[141]andby1March2012,thenationalaveragewas$3.74pergallon.CaliforniapricesarehigherbecausetheCaliforniagovernmentmandatesuniqueCaliforniagasolineformulasandtaxes.[142] IntheUnitedStates,mostconsumergoodsbearpre-taxprices,butgasolinepricesarepostedwithtaxesincluded.Taxesareaddedbyfederal,state,andlocalgovernments.Asof2009,thefederaltaxwas18.4¢pergallonforgasolineand24.4¢pergallonfordiesel(excludingreddiesel).[143] About9percentofallgasolinesoldintheU.S.inMay2009waspremiumgrade,accordingtotheEnergyInformationAdministration.ConsumerReportsmagazinesays,"If[yourowner'smanual]saystouseregularfuel,doso—there'snoadvantagetoahighergrade."[144]TheAssociatedPresssaidpremiumgas—whichhasahigheroctaneratingandcostsmorepergallonthanregularunleaded—shouldbeusedonlyifthemanufacturersaysitis"required".[145]Carswithturbochargedenginesandhighcompressionratiosoftenspecifypremiumgasbecausehigheroctanefuelsreducetheincidenceof"knock",orfuelpre-detonation.[146]Thepriceofgasvariesconsiderablybetweenthesummerandwintermonths.[147] Thereisaconsiderabledifferencebetweensummeroilandwinteroilingasolinevaporpressure(ReidVaporPressure,RVP),whichisameasureofhoweasilythefuelevaporatesatagiventemperature.Thehigherthegasolinevolatility(thehighertheRVP),theeasieritistoevaporate.Theconversionbetweenthetwofuelsoccurstwiceayear,onceinautumn(wintermix)andtheotherinspring(summermix).ThewinterblendedfuelhasahigherRVPbecausethefuelmustbeabletoevaporateatalowtemperaturefortheenginetorunnormally.IftheRVPistoolowonacoldday,thevehiclewillbedifficulttostart;however,thesummerblendedgasolinehasalowerRVP.Itpreventsexcessiveevaporationwhentheoutdoortemperaturerises,reducesozoneemissions,andreducessmoglevels.Atthesametime,vaporlockislesslikelytooccurinhotweather.[148] Gasolineproductionbycountry[edit] Gasolineproduction,thousandbarrelsperday,2014 (thousandbarrelsperday,Source:USEnergyInformationAdministration,TheGlobalEconomy.com)[149] Country Gasolineproduction US 9571 China 2578 Japan 920 Russia 910 India 755 Canada 671 Brazil 533 Germany 465 SaudiArabia 441 Mexico 407 SouthKorea 397 Iran 382 UK 364 Italy 343 Venezuela 277 France 265 Singapore 249 Australia 241 Indonesia 230 Taiwan 174 Thailand 170 Spain 169 Netherlands 148 SouthAfrica 135 Argentina 122 Sweden 112 Greece 108 Belgium 105 Malaysia 103 Finland 100 Belarus 92 Turkey 92 Colombia 85 Poland 83 Norway 77 Kazakhstan 71 Algeria 70 Romania 70 Oman 69 Egypt 66 UAEmirates 66 Chile 65 Turkmenistan 61 Kuwait 57 Iraq 56 Vietnam 52 Lithuania 49 Denmark 48 Qatar 46 Comparisonwithotherfuels[edit] Thissectionneedsadditionalcitationsforverification.Pleasehelpimprovethisarticlebyaddingcitationstoreliablesources.Unsourcedmaterialmaybechallengedandremoved.(December2020)(Learnhowandwhentoremovethistemplatemessage) Seealso:Energycontentofbiofuel Belowisatableofthevolumetricandmassenergydensityofvarioustransportationfuelsascomparedwithgasoline.Intherowswithgrossandnet,theyarefromtheOakRidgeNationalLaboratory'sTransportationEnergyDataBook.[150] Fueltype[a] GrossMJ/L      MJ/kg GrossBTU/gal(imp) GrossBTU/gal(U.S.) NetBTU/gal(U.S.)     RON Conventionalgasoline 34.8 44.4[151] 150,100 125,000 115,400 91–98 Autogas(LPG)(ConsistingmostlyofC3andC4hydrocarbons) 26.8 46 95,640 108 Ethanol 21.2[151] 26.8[151] 101,600 84,600 75,700 108.7[152] Methanol 17.9 19.9[151] 77,600 64,600 56,600 123 Butanol[2] 29.2 36.6 125,819 104,766 91–99[clarificationneeded] Gasohol 31.2 145,200 120,900 112,400 93/94[clarificationneeded] Diesel(*) 38.6 45.4 166,600 138,700 128,700 25 Biodiesel 33.3–35.7[153][clarificationneeded] 126,200 117,100 Avgas(highoctanegasoline) 33.5 46.8 144,400 120,200 112,000 Jetfuel(kerosenebased) 35.1 43.8 151,242 125,935 Jetfuel(naphtha) 127,500 118,700 Liquefiednaturalgas 25.3 ~55 109,000 90,800 Liquefiedpetroleumgas 46.1 91,300 83,500 Hydrogen 10.1(at20kelvin) 142 130[154] (*)Dieselfuelisnotusedinagasolineengine,soitslowoctaneratingisnotanissue;therelevantmetricfordieselenginesisthecetanenumber. Seealso[edit] Energyportal Aviationfuel –Fuelusedtopoweraircraft Butanolfuel –Fuelforinternalcombustionengines–replacementfuelforuseinunmodifiedgasolineengines Biogasoline –Gasolineproducedfrombiomass-petrolderivedfrombiomasssuchasalgae Dieselfuel –Liquidfuelusedindieselengines Fillingstation –Facilitywhichsellsgasolineanddiesel Fueldispenser Fuelsavingdevice Gastoliquids Gasolineanddieselusageandpricing –Wikimedialist Gasolinegallonequivalent –Amountofalternativefuelittakestoequaltheenergycontentofoneliquidgallonofgasoline Hydrogenfuel –Usedinfuelcellsorinternalcombustionengines Internalcombustionengine (ICE) –Engineinwhichthecombustionofafueloccurswithanoxidizerinacombustionchamber Jerrycan –Robustpressedsteelliquidcontainer Listofautomotivefuelretailers Listofgasolineadditives Natural-gascondensate#Dripgas –Low-densitymixtureofhydrocarbonliquids Syntheticgasoline Octanerating –Standardmeasureoftheperformanceofanengineoraviationfuel Worldoilmarketchronologyfrom2003 –Chronologyofeventsaffectingtheoilmarket Notes[edit] ^Thetypeneedsmorereferenceswhichspecifycompositionsofeachfuel,pluscitations,toavoidvaguenessinnumbers References[edit] ^"Gasoline—apetroleumproduct".U.SEnergyInformationAdministrationwebsite.U.SEnergyInformationAdministration.12August2016.Archivedfromtheoriginalon24May2017.Retrieved15May2017. ^"Whysmallplanesstilluseleadedfueldecadesafterphase-outincars".NBCNews.Archivedfromtheoriginalon2June2021.Retrieved2June2021. ^"RaceFuel101:LeadandLeadedRacingFuels".Archivedfromtheoriginalon25October2020.Retrieved30July2020. ^"PreventingandDetectingUndergroundStorageTank(UST)Releases".UnitedStatesEnvironmentalProtectionAgency.13October2014.Archivedfromtheoriginalon10December2020.Retrieved14November2018. ^"EvaluationoftheCarcinogenicityofUnleadedGasoline".epa.gov.Archivedfromtheoriginalon27June2010. ^Mehlman,MA(1990)."Dangerouspropertiesofpetroleum-refiningproducts:carcinogenicityofmotorfuels(gasoline)".Teratogenesis,Carcinogenesis,andMutagenesis.10(5):399–408.doi:10.1002/tcm.1770100505.PMID 1981951. ^Baumbach,JI;Sielemann,S;Xie,Z;Schmidt,H(15March2003)."Detectionofthegasolinecomponentsmethyltert-butylether,benzene,toluene,andm-xyleneusingionmobilityspectrometerswitharadioactiveandUVionizationsource".AnalyticalChemistry.75(6):1483–90.doi:10.1021/ac020342i.PMID 12659213. ^"ReleasesoremissionofCO2perLiteroffuel(Gasoline,Diesel,LPG)".7March2008.Archivedfromtheoriginalon1August2021.Retrieved30July2021. ^"GlobalClimateChange:VitalSignsofthePlanet".NASA.doi:10.1088/1748-9326/8/2/024024.Archivedfromtheoriginalon11April2019.Retrieved16September2021.{{citejournal}}:Citejournalrequires|journal=(help) ^ab"Theetymologyofgasoline".OxfordEnglishDictionary.Archivedfromtheoriginalon29July2017.Retrieved30July2017. ^See: OxfordDictionaries(blog):Theetymologyofgasoline 38thCongress.SessionsI.Chapter173:AnActtoprovideInternalRevenuetosupporttheGovernment,topayInterestonthePublicDebt,andforotherPurposes,1864,p.265."… ;Andprovided,also,Thatnaphthaofspecificgravityexceedingeightydegrees,accordingtoBaume'shydrometer,andofthekindusuallyknownasgasoline,shallbesubjecttoataxoffivepercentumadvalorem."SeeLibraryofCongress(US)Archived13November2018attheWaybackMachine Seealso:Stevens,Levi,"Improvedapparatusforvaporizingandaeratingvolatilehydrocarbon,"Archived27August2018attheWaybackMachineU.S.Patentno.45,568(issued:20December1864).Fromp.2ofthetext:"Oneoftheproductsobtainedfromthedistillationofpetroleumisacolorlessliquidhavinganetherealodorandbeingthelightestinspecificgravityofallknownliquids.Thismaterialisknownnowincommercebytheterm"gasoline."" ^"petroleum"Archived16May2020attheWaybackMachine,intheAmericanHeritageDictionary ^MedievalLatin:literally,rockoil=Latinpetr(a)rock(