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SUSTAINABLE ENERGY

JULIANR.H.ROSS

EmeritusProfessor,UniversityofLimerick,Limerick,Ireland; MemberoftheRoyalIrishAcademy(MRIA);Fellowofthe RoyalSocietyofChemistry(FRSC)

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Notices

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1.Introduction1

Energyproductionandthegreenhouseeffect1

Greenhousegases4

Consequencesofthegreenhouseeffect9

Thesourcesofgreenhousegasemissions11

2.Traditionalmethodsofproducing,transmittingandusing

Concludingremarks47

3.Lessconventionalenergysources49 Introduction49 Nuclearenergy50

Geothermalenergy55 Tidalenergy59

Wavepower62

Hydroelectricpower63 Windpower67

Solarpower69

Concludingremarks75

4.Theproductionandusesofhydrogen77

Introduction77

Theproductionofhydrogenfromnaturalgasbysteamreforming77

Theproductionofhydrogenfromnaturalgasbyothermethods89

Methanolproduction96

ProductionoffuelsusingtheFischerTropschprocess97

Productionofammonia99

Conclusions102

5.Biomassasasourceofenergyandchemicals103

Introduction103

Woodasasourceofenergyandpaper104

Non-traditionalusesofbiomass:Firstandsecondgenerationbio-refinery processes112

Concludingremarks129

6.Transport131

Introduction131

Historicaldevelopmentofmechanicallydriventransport131 Exhaustemissioncontrol143

Hybridvehicles150

Plug-inhybridvehicles152

Batteryelectricalvehicles154

Fuelcellvehicles159

Concludingremarks160

7.Batteries,fuelcellsandelectrolysis163

Introduction163

TheVoltapile,Faradayandtheelectrochemicalseries163

Half-cellEMF’sandtheelectrochemicalseries167

Thekineticsofelectrochemicalprocesses170

Electrochemicalbatteries175

Flowbatteries185 Fuelcells186 Electrolysis192

8.Thewayforward:NetZero197 Introduction197

Hydrogenproductionusingrenewableenergy199

Fuelcellstobeusedfortransportationpurposes203

Solidoxidehydrolysiscells(SOEC’s)forhydrogenproductionandtheiruse forthesynthesisofgreenammoniaandmethanol205

Tailpiece221 Index 225

Preface

Itisnotpossibletoopenanewspaperormagazinewithoutreadingofsome aspectoftheglobalproblemofclimatechangeandofthemeasuresthatare necessarytocombatitsothatwecanachieve‘zerocarbon’beforetheyear 2050.Therehasbeenasteadyincreaseintheemissionofgreenhousegases sincetheIndustrialRevolutionandtheaimofallthosecountriesthathave signeduptotheParisAccordistobringbacktheresultanttemperaturerise tonomorethan2°C(andevento1.5°C)withinfewerthan30years.

Thisbookconsidersmanyaspectsofthepotentialusesof‘sustainable energy’.Inthiscontext,thisistheenergythatcanbeobtainedbyusing renewableresourcessuchaswindpower,hydroelectricpowerorsolarradiation,andthebookdiscusseshowthisenergycanbeusedinplaceofconventionallyderivedenergyfromfossilreserves:coal,oilandnaturalgas.In ordertosetthescene,thebookalsodiscussesinsomedetailthemanywaysin whichconventionalenergyiscurrentlyused.

ThefirstchaptersetsthescenebyconsideringsomeaspectsofthegreenhouseeffectandoutlinestheobjectivesoftheParisAccordthatisaimedat reducingtheemissionsresponsiblefortheeffect.Itthentracestheoriginsof thegreenhouseeffect,discussingsomehumanactivities(manyofwhichare discussedlaterinthebook)thathavetakenplacesincetheIndustrialRevolutionandhavecontributedtotheincreasedemissions.

Thebookthenconsiderssomeimportantexistingindustrialactivities,all relatedtotheuseofenergycreatedfromtheuseoffossilfuels,coaloiland naturalgas,eachofwhichresultsintheemissionofgreenhousegases.Some oftheseemissionscanbereducedbymethodssuchascarboncollectionand storage,butanalternativeistoproducesomeofthechemicalsandfuelson whichwerelybyusingbiomass-derivedmaterials.Hence,theuseofbiomassasasourceofenergyandchemicalsisthenconsidered.

Transport,inoneformortheother,isresponsibleforasignificantshare ofourgreenhousegasemissions.Thedevelopmentsthathaveoccurredsince theIndustrialRevolutionofvariousformsoftransportareoutlinedand moderndevelopmentssuchastheuseofhybridengines,batterypower andfuelcellsarethenconsidered.Thisleadstoadetaileddiscussionofvarioustypesofbatteriesandfuelcellsfollowedbyasectionconsideringthe potentialimportanceofelectrolysisbroughtaboutusingrenewableenergy asameansofproducinghydrogenandsyngas.

Thefinalchapterconsidershowgreenhydrogenorsyngasproduced usingelectrolyticmethodsfuelledbyrenewableelectricitycanbeusedin industrialapplicationssuchasammoniaandmethanolsynthesis,theproductionofsteelandcementmanufacture.Italsoconsiderstheimportanceof achievingreductionsinemissionsfromcommercial,domesticandagriculturalsources.

ThereductionsrequiredtoallowusreachthetargetssetintheParis Accordareenormousandtheprogresstowardsachievingtheseaimshas beendisappointinglyslowuntilnow.Governmentsandresponsibleagencies mustthereforepaysignificantlygreaterattentiontowaysinwhichobjectives canbeachievedandcanonlymanagethatbyapplyingthe‘carrotandstick approach’:offeringincentivestoallenergyusersthatencourageenergysavinginitiativesandtheintroductionofnewmethodswhileatthesame timepenalisinginactivity.

Acknowledgements

AsIdidinmyprevioustwobooks,Ifirstthanktheverymanypeoplewith whomIhaveworkedovertheyearsfortheireffortsandenthusiasm,especiallythestudentsandpostdocsfrommyvariousresearchgroups,toomany tonameindividually,whohavehelpedmebuildupmyknowledgeofcatalysisandrelatedfields.Thanksarealsoduetothemanyscientistsandengineerswithwhommydifferentresearchgroupshavecollaboratedandfrom whomIhavelearntmuchabouttheapplicationsandexploitationoffundamentalresearchinthefieldofheterogeneouscatalysis.Thiscollaborative workwascarriedoutwithfundingprovidedbymanysources,particularly byvariousEUresearchprogrammes.

IthankElsevierandthemanypeoplefromthatcompanywithwhomI havecollaboratedduringmyeditorialworkfor AppliedCatalysis and CatalysisToday andintheproductionofthethreebooksthatIhavenowwritten andpublishedwiththem.Inparticular,IthankKostasMarinakiswhonot onlyguidedmethroughtheprocessinvolvedintheplanningofthisbook butwithwhomIhavehadmanypreviousinteractionsduringmyworkasan editor.Iwishhimwellinhisretirement.ThanksarealsoduetoKostas’s successor,AnitaKoch,forhermorerecentinvolvementwiththeproductionofthisbook;toNarmathaMohanforherassistanceinensuringthatthe necessarypermissionhadbeenobtainedtoreproducecopyrightmaterial; andtoBharatwajVaratharajanforhiscarefulandhelpfulworkonthefinal productionandduringtheproofreadingstage.IparticularlythankAlice Grantwho,asthemostrecentElsevierdeskeditorinvolved,hascheerfully andhelpfullyworkedwithmeformostofthewritingprocess.

Mythanksareduetotwogoodfriendswho,eachinparticularway, helpedmeduringthewritingphase:firstly,mycolleagueandlong-standing collaborator,MichaelHayes,whoverykindlyreadthroughthefirstdraftof Chapter5 (BiomassasaSourceofEnergyandChemicals)andnotonlyprovidedmewithusefulcommentsbutalsogavemeinvaluableinformationon soilorganicmatter;andsecondly,TonyHilley,aretiredoffshoreoilandgas engineer,whoencouragedmethroughoutthewritingphasebyproviding mewithalargenumberofimportantweblinkstorecentdevelopmentsin thefieldofenergy.IalsothankMiguelBan ˜ aresforhiscommentsonthe contentsofthecompletedmanuscriptandforsuggestingtheterm‘Mount Sustainable’.

x Acknowledgements

Finally,Imustoncemoreexpressmysincerethankstomywife,Anne, whohasencouragedandsupportedmeduringthewritingofyetanother book.Thissupportwasevenmoreimportantforthecurrentvolumeas shehaspatientlytoleratedmyinvolvementinthetaskduringaperiodwhen COVID-19intrudedonourexistenceandforcedlongperiodsofselfisolation.

JulianR.H.Ross

CHAPTER1

Introduction

Energyproductionandthegreenhouseeffect

Solaractivityandglobalwarming

Forcenturies,wehavereliedonournaturalresourcesfortheprovisionof energy.Earlymanreliedonthecombustionofbiomass(predominantly wood)toprovideheatandfuelforcooking.Verymuchlater,roughlyat thetimeoftheIndustrialRevolution,hediscoveredcoal,oilandnatural gasandthesediscoveriesledtoourcurrentalmosttotaldependenceonfossil fuelsfortheprovisionofenergy.a UntiltheIndustrialRevolution,the earth’spopulationwaspredominantlyagrarianandanyfluctuationsinclimatethatoccurredwererelatedonlytovariationsinsolaractivity.Since then,however,therehasbeenasteadyincreaseintheaverageglobaltemperatureanditisnowgenerallyrecognisedthatthischangeoftemperatureis relatedtoincreasedemissionsoftheso-calledgreenhousegases.

Fig.1.1 showsthevaluesofthesolarirradianceandalsotheglobaltemperaturethathavebeenmeasuredovertheperiodsince1880;althoughthere havebeensomesignificantchangesinthesolaractivity(andtherewasa markedmaximumvaluearound1960),themeasuredvalueshaveremained relativelysteadyoverthelast50years.However,therehasbeenaverysignificantincreaseinglobaltemperatureduringthesameperiod.Itisnow generallyaccepted(see Fig.1.2)thathumanactivitieshavebeenresponsible forthisincreaseintemperature.b

a Wealsorelyonpetroleumderivativesforthemanufactureofmanyoftheotherresourcesthatwenow takeforgranted:polymers,dyestuffs,pharmaceuticals,detergents,etc.However,ourfossilfuelreserves aregraduallydiminishingandtheymustthereforebeusedmuchmorestrategically.

b Ausefulsummaryofsomeaspectsofclimatechangearetobefoundinthepublication“VitalClimate ChangeGraphics”publishedbyUNEP/GRID-Arendal;thisisavailableasafreepdffrom https:// www.grida.no/publications/254/

Fig.1.1 Globaltemperatureandsolaractivitysince1880.Theyearlyvariationsofboth theseparametersareshownbylightercurvesandthesehavebeenaveragedtogivethe moredistinctcurves. (Source: https://climate.nasa.gov/ .)

Fig.1.2 IPPCkeyfindings.Predictedmajorchangesduetoglobalwarming. (Source: https://climate.nasa.gov/ .)

Fig.1.3 Schematicrepresentationofthegreenhouseeffect. (Source:FromWikipedia (https://en.wikipedia.org/wiki/Greenhouse_effect/ ).)

Thegreenhouseeffect

Muchlifeonearthasweknowitdependsonthelightradiationfromthesun thatpenetratesthroughtheatmospheretowarmtheearth’ssurface.Without theatmosphere,muchoftheincidentradiationwouldbere-emittedfrom thesurfaceandwouldbetotallylostinspace.Fortunatelyhowever,the atmosphereactsinthesamewayasdoestheglassinagreenhouse,c absorbing andreflectingbackmuchofthere-emittedradiationandensuringthatthe temperatureoftheatmosphereisincreased.Thisprocessisshownschematicallyin Fig.1.3.Theresultanttemperatureonearthisadelicatebalanceof thelevelsofincomingandreflectedradiationandisthusverysusceptibleto changesinthecompositionoftheatmosphere;iftoomuchofthereflected radiationisretainedbytheatmosphere,thetemperatureoftheearth willrise.

c Withagreenhouse,almostalltheincidentlightpassesthroughtheglassandisabsorbedbythesoil withinthestructure;someoftheenergyisthenre-emittedatadifferentwavelengthbutthisisnow absorbedbytheglass,ensuringthattheincreasedtemperatureinthegreenhouseismaintained.

Greenhousegases

Table1.1 liststhemaingreenhousegasesassociatedwithglobalwarming,givingforeachthechemicalformula,theglobalwarmingpotentialrelativeto thatforCO2 overa100-yearlifespanandtheatmosphericlifetimeinyears.

Table1.2 showsthemainsourcesofthesegreenhousegasesandalsogives thepre-industrialatmosphericconcentrationsandthecurrentatmospheric concentrations.Thefirstthreegasesallexistedinthepre-industrialera, althoughtheconcentrationshaveallincreasedsince,whilethelastentries allrefertoman-madegasesintroducedoverthelastcentury.Weobtainan approximationtotherelativecontributionsoftherelevantgasestoglobal warmingifwemultiplythecurrentconcentrationsofeachgasbytheglobal warmingpotentialfrom Table1.1.Theresultantfiguresshowthatthemain culpritsareCO2,methaneandnitrousoxide:nottakingintoaccountthesmall contributionsofthefluorine-containingmolecules,CO2 contributes73.3% ofthetotalglobalwarmingpotentialofthesegaseswhilemethanecontributes 8.5%andN2Ocontributes18.2%.Althoughthecontributionsofthevarious fluorinatedmoleculesarerelativelylow,itneedstoberecognisedthatthelifetimesofthesespeciesaresignificantlyabovethoseoftheothergreenhouse gasesanditisforthisreasonthattheyarenolongermanufactured.Aswewill seebelow,thereareanumberofothergreenhousegases,someofwhichcontributetoglobalwarmingwhileothersdonot.Watervapourisoneexample ofagaswhichdoesnotcontributedirectlytoglobalwarmingandozoneis

Table1.1 Globalwarmingpotentialandatmosphericlifetimeforthemostimportant greenhousegases.

Table1.2 Themostimportantsourcesofthemajorgreenhousegasesandtheir preindustrialandrecent(2011)concentrations.

GreenhousegasMajorsources

CarbondioxideFossilfuel combustion Deforestation Cement production

MethaneFossilfuel production Agriculture

Landfills 7221803

NitrousoxideFertilizer application

Fossilfueland biomass combustion

Industrial processes 271324

Chlorofluorocarbon12(CFC-12) Refrigerants00.0527

Hydofluorocarbon23(HFC-23) Refrigerants00.024 SulfurhexafluorideElectricity

another.Wewillnowconsidereachgreenhousegasinturn,startingwith watervapour.

Watervapour

Themostimportantgreenhousegasesarewatervapourandcarbondioxide. Bothoftheseresultfromthecombustionoffossilfuelsbutmayalsoarise fromothersources.Water-vapour,whichresultspredominantlyfromthe evaporationofsurfacewater,hasafeedbackeffect:itformscloudsinthe atmosphereandtheseleadtoprecipitation,thishavingtheconsequencethat thelevelofwater-vapourintheatmosphereiswellcontrolled.Theclouds alsoreflectsomeoftheradiation(UV,visibleandinfra-red)reachingthe

atmospherefromthesun,thisalsorestrictingthetemperaturerise.Oneconsequenceofthepresenceofincreasedpartialpressuresofcarbondioxidein theatmosphere(seebelow)isthattheresultingtemperaturerisealsocauses anincreaseinthepartialpressureofthewaterintheatmosphere,thusgiving risetoafurtherincreaseinthetemperature.Hence,watervapourhasan indirecteffectonglobalwarming.

Carbondioxide

Eventhoughtheconcentrationofcarbondioxideintheatmosphereismuch lowerthanthatofwater,itseffectismuchgreatersincethereisnoequivalent feedbackmechanismtothatwithwater:oncethecarbondioxidereachesthe atmosphere,itsresidencetimethereisverymuchgreaterthanthatofwater. ThedoublebondsoftheC]OlinkagesoftheCO2 absorbmuchofthe infraredradiationemittedfromtheearthandpreventthisradiationfrom leavingtheatmosphere.Theresultisanincreaseinatmospherictemperature.ItshouldberecognisedthattheCO2 reachingtheatmospherecan comefrommanysourcesapartfromcombustion,forexample,respiration andvolcaniceruptions.Itcanalsoarisefromdeforestationandchangesin landuse.Asdiscussedabove,theincreaseinatmospherictemperaturecaused bytheCO2 alsohasaneffectonthelevelofwatervapourintheatmosphere sincethesaturationvapourpressureofthewaterincreaseswithincreasing temperatureandhencethismagnifiestheeffectoftheincreasein CO2 concentration.AtmosphericCO2 isessentialforthegrowthofplants andalltypesofvegetation.Hence,werelyonasteadypartialpressureof CO2 toenableagriculturalactivities.Wewillreturntothesubjectof CO2 utilisationinsubsequentchapters.Asshownin Fig.1.4 of Box1.1, therehasbeenadramaticincreaseintheconcentrationofCO2 intheatmosphereoverthelast70years.

Methane

Methane(CH4),thesimplesthydrocarbonmolecule,mayarisefromanumberofsources,bothnaturalandman-made.Itisproducedbythedecompositionofwastesinlandfills,fromagriculturalsourcessuchasrice paddies,fromdigestiveprocessesofruminants(e.g.cattleandsheep)and manuremanagementfromdomesticlivestock.Itwasalsocommonlyemittedaswastefromoilwelloperationsandasleakagesfromchemicalprocessing;however,bothofthesesourcesarenowmuchmorecarefully

controlled.(See Box1.2 foranexampleofmethaneemission.)Methaneis amuchmoreactivegreenhousegasthanisCO2,its‘globalwarmingpotential’beingmuchhigher(see Table1.1).Theatmospherealsocontains yetlowerconcentrationsofotherhydrocarbonssuchasthevapoursof petroleumanddieselcomponentsandthesetooaregreenhousegases. Methaneandtheotherhydrocarbonshavemuchlongerlifetimesthandoes CO2 intheatmosphere;whileCO2 isremovedbynaturalprocesses,the

BOX1.1VariationofglobalCO2 concentrationsasafunction oftime

Fig.1.4 showstheconcentrationofCO2 intheatmosphereasafunctionoftimeover manycenturies.Thesedatahavebeencompiledfromtheanalysisofairbubbles trappediniceoverthelast400,000years.Duringiceages,thelevelswereabout 200ppm(ppm)andtheyrosetoaround280ppminthewarmerinterglacial periods.Theriseafterabout1950isattributabletoarapidincreaseintheuseof fossilfuelsaswillbediscussedfurtherinlatersections.

Fig.1.4 Thevariationincarbondioxideconcentrationasafunctionoftime.Itis clearthattherehasbeenadramaticincreaseinthelevelofcarbondioxidesince 1950thatiswelloutsidethenormaltemporalvariations. (Source:https://climate. nasa.gov/resources/)

BOX1.2Methaneemissionsfromtheproductionofbitumen fromoilsands

Thereisasignificantindustrybasedontheextractionofbitumenfrom undergroundreservoirscontainingoilsands.Thebitumenisheatedusingthe injectionofsteamtodecreaseitsviscosityandtomakeitflowmoreeasily.The steamisgeneratedbythecombustionofnaturalgas(methane)andthisprocess givesrisetosignificantCO2 emissions,thesecontributingtoglobalwarming. Canada’sOilSandsInitiativeAlliance(COSIA)isattemptingtofindwaysof reducingtheseemissionsandhasannouncedthatitwillassistinnovatorsin developingnewroutestoreducetheemissionsformedduringthesteam generationstep,preferablyproducingasequestration-readyproduct(e.g. concentratedCO2)orasaleableproduct(e.g.carbonblack).

https://cosia.ca/blog/helping-clear-air-oil-sands-emissions-natural-gasdecarbonization/

hydrocarbonsarerelativelystable.Asaresult,theyallhavehigherglobal warmingpotentials(Table1.1).d

Nitrousoxide

Nitrousoxide(N2O)isaverypowerfulgreenhousegas(see Table1.1 )that isformedbysoilcultivationpractices,especiallybytheuseofnitrogenous fertilisers;itisalsoformedbyfossilf uelcombustion,nitricacidproduction andbiomassburning.ItshouldberecognisedthatN2Oisonlyaminor constituentofso-calledNOx,amixtureoftheoxidesofnitrogen (N2O,NOandNO2),formedinhigh-temperaturecombustionprocesses e suchasthoseinvolvedinelectricity generationandinternalcombustion engines.NOx isconsideredtobeanatmosphericpollutantanditsemission isassociatedwiththeformationof‘acidrain’;theNO x emissionsfrom thesesourcesaregenerallycontrolledbycatalyticreductionprocesses. f

d Itshouldbenotedthattheglobalwarmingpotentialofmethaneistimedependentasitisgradually destroyedbyoxidationprocessesintheatmosphere;overperiodslessthan100years,thevalueofthe globalwarmingpotentialismuchlarger.

e Athightemperaturesandinexcessoxygen,thermodynamicsfavourstheformationofNO2

f ForadescriptionofthecontrolofNOxemissionsfrompowerstationsandautomobiles,see ContemporaryCatalysis – FundamentalsandCurrentApplications,JulianR.H.Ross, www.elsevier. com/books/contemporary-catalysis/ross/978-0-444-634740-0.Seealso Chapter2

Ozoneandchlorofluorocarbons

Ozoneisalsoagreenhousegas.Itisformedinthetropospherebytheinteractionofsunlightwithotheremissionssuchascarbonmonoxideormethane andalsobyinteractionwithhydrocarbonsandNOxfromautomobileemissions.Thelifetimeofozoneisrelativelyveryshort(daystoweeks)anditsdistributionisveryvariable.ItabsorbsharmfulUVradiationandwearetherefore dependentonthepresenceoftheozonelayer.Thecreationofanozonehole overtheAntarcticisascribedtotheemissionofchlorofluorocarbons(CFCs), anotherclassofpowerfulgreenhousegas,andthishasledtothebanningofthe productionofthesemolecules;theproductionofotherhydrofluorocarbons (HFCs)andperfluorocarbons(PFCs)isalsobeingphasedout.g

Consequencesofthegreenhouseeffect

Itisgenerallyrecognisedthatitisdifficulttopredicttheconsequencesof changingthecompositionofthenaturallyoccurringatmosphericgreenhousethatsurroundstheEarth.However,itisextremelylikelythattheaveragetemperatureoftheEarthwillcontinuetorise;eventhoughsomeareas willbecomecooler,otherswillbecomewarmer.Warmerconditionswill probablygiverisetomoreevaporationandprecipitationalthoughsome regionswillbecomewetterandotherswillbecomedrier.Astrongergreenhouseeffectwillwarmtheworld’soceansandthesewillexpandandincrease sealevels;additionally,glaciersandothericewillmelt,thusfurtherincreasingthesealevel.TheincreasedCO2 concentrationintheatmospherewill encouragesomecropsandotherplantstogrowmorerapidlyandtouse watermoreefficiently;however,atthesametime,highertemperatures andchangeintheclimatepatternsmaycausechangesinthedistribution oftheareaswherecropsgrowbest.Althoughclimatechangehasbeen thesubjectofgreatconcernforquitesometime,itwasonlyabout30years agothatscientistsbecameparticularlyconcernedaboutthechangeswhich wereoccurring;h see Box1.3.Arrheniusdiscussedin1886theimportanceof theincreasesinemissionsofcarbondioxideresultingfromcoal-burning;he arguedthatthiswouldleadtoimprovedagriculturalpracticesandbetter

g ThisphasingoutispartoftheKyotoProtocol(2005);theUShasnotratifiedthisinternational agreement.

h AnexcellentarticlebyAndrewRevkinoutliningsomeofthehistoryofawarenessoftheproblemsof climatechangeistobefoundintheNationalGeographicMagazineofJuly2018(https://www. nationalgeographic.com/magazine/2018/07/embark-essay-climate-change-pollution-revkin/). However,therearemanyothersucharticlesavailableontheweb.

growthofcrops.AnarticlebyWaldemarKaempffertintheNewYork Timesasearlyas1956(October28)i predictedthattheincreasedemissions fromenergyproductionwouldleadtolong-lastingenvironmentalchanges. Thisarticlepointedoutveryclearlythatanimpedimenttocounteracting thesechangeswastheabundanceofcoalandoilinmanypartsoftheworld andthatthesefossilfuelswouldcontinuetofeatureinindustrialuseaslongas itwasfinanciallybeneficialtousethem.However,itwasnotuntil1988that theWorldMeteorologicalOrganisation(WMO)establishedtheIntergovernmentalPanelonClimateChange(IPCC).TheIPCCsummarisesthescientificdevelopmentsincounteringclimatechangeintheIPCCAssessment Reportsthatarepublishedeveryfivetosixyears,thesebeingcompiledin associationwithanumberofotherrelatedreportsfromthepanel.(TheSixth SynthesisReportisduein2022.)j Inparalleltotheseactivities,therehave beenalargenumberofreportsbyotheragencies,bothinternationaland national,someofwhichwillbequotedbelow.Therehavealsobeentwo importantinternationalagreementsonhowclimatechangeshouldbe counteracted,theKyotoAgreementof1992andtheParisAgreementof 2015,bothestablishedundertheauspicesoftheUnitedNationsFramework ConventiononClimateChange(UNFCCC).Justfewerthan200countries weresignatoriestotheseagreements,theaimsofwhichbeingtoreducetheemissionofgreenhousegases.k Theseagreementswillbediscussed furtherbelow.

BOX1.3Theimportanceoftheexistenceofagreenhouse effectonearth

Iftheearthdidnothaveaneffectiveshieldinggreenhouselayercontaininghigh levelsofwatervapouraswellasCO2 andtheothergreenhousegases,muchof thelightofallwavelengthsreachingthesurfaceoftheearthfromthesun wouldbereflectedbackintospacewithoutwarmingtheplanet.Theplanet Marshasarelativelythinatmosphereconsistinglargelyofcarbondioxidebut littleornowatervapourandthisresultsinaweakgreenhouseeffect.Asa Continued

i SeeNewYorkTimesDecember8,2015: https://www.nytimes.com/interactive/projects/cp/ climate/2015-paris-climate-talks/from-the-archives-1956-the-rising-threat-of-carbon-dioxide

j TheMontrealProtocoltoreducetheemissionofcompoundsthataffecttheozonelayersuchasthe chlorofluorocarbonsmentionedabovewasagreedin1987.

k TheUSunderPresidentTrumphadannouncedthatitwasgoingtoleavetheParisAgreementbutthat decisionhasnowbeenreversedbyPresidentBiden;ofthecountrieswithover1%shareoftheglobal emissions,onlyIranandTurkeyarenotpartiestotheagreement.

Theglobalemissionofallgreenhousegasesin2010was48gigatonnesof CO2 equivalentanditwasestimatedthatthisfigurewouldincreaseto53.5 gigatonnesin2020.Whatismuchmorealarmingisthattheamountwill increaseto70gigatonnesby2050unlessactionistakentoreducegreenhouseemissions.Theseunfetteredincreaseswillgiverisetototallyunacceptableglobaltemperatureincreases,theseinturngivingrisetomyriad problemsfortheworld’sinhabitants.TheKyotoProtocolandtheParis Agreementhaveledtotwotargetsrelatingtotemperaturerise:thefirst,a limitof2.0°Ccomparedtotheemissionsinthepre-industrialera;and thesecond,pursuingatthesametimemeanstolimitthetemperature increaseto1.5°C.

Fig.1.5 illustratesthepredictedchangesoccurringfordifferentscenarios envisagedintherun-uptotheParisAccord,rangingfromtheabsenceofany policy(resultinginaveryhighchancethattheglobaltemperaturerisewillbe wellabove4°C)toaverystrictpolicy(whenthechanceofthetemperature approachingpre-industriallevelswillbemuchgreater).Thesolidcurvesof thediagramshowthepredictedemissionsofCO2 fordifferentscenarios, fromnoaction(topcurve)tothemostambitiousseriesofactionswith higherratesofdecarbonisation(1.5°Cwarming,bottomcurve).Itwillbe seenthatonlythelatterapproachgivesanysignificantreductionintheemissionofgreenhousegases.Theslightlylowersetofambitions,withconstant ratesofdecarbonisation(2°Cwarming)givesalevellingoffofthelevelsof CO2 afterabout2030.

Thesourcesofgreenhousegasemissions

Therehavebeenanumberofverydetailednationalandinternationalreports thatgiveinformationonemissionsofgreenhousegasesandlistthemain BOX1.3Theimportanceoftheexistenceofagreenhouse effectonearth cont’d result,thesurfaceofMarsislargelyfrozenandthereisnoevidenceofanylifeform. Incontrast,VenushasamuchhigherconcentrationofCO2 initsatmosphere (150,000timesasmuchasonEarthand19,000asmuchasonMars)andthe surfacetemperatureis+460°C.Again,thisatmospherewouldnotbeamenableto lifeasweknowit.(See https://agreenerfutureblog.wordpress.com/1-the-naturalgreenhouse-effect/1-4-greenhouse-effect-on-other-planets/; https://earthsky.org/ space/venus-mars-atmosphere-teach-us-about-earth/)

Fig.1.5 ChangesincarbondioxideemissionsenvisionedinParisAccord.Theeffectson CO2 emissionsofeithernochangeoradoptingvariousstrategies(seetext). (Adapted fromClimateScienceSpecialReport(USGlobalChangeProgram),FourthNational ClimateAssessment(NCA4)Vol.1,Chapter14.2: https://science2017.globalchange.gov/ .)

sources.Someofthesereportswillbediscussedinmoredetailinlatersections.Oneofthemostrelevantofthesereportsforthepresentpurposesis onebytheEuropeanEnvironmentAgencyl andthefollowingsectionswill summarisesomeofitsmostrelevantmaterial.

Table1.3 showsdataforthetotalemissionsofgreenhousegasesfrom Europeancountriesin2017andalsoshowsthechangesinemissionsthat haveoccurredintheperiodbetween1990and2017,thegreenhousegas emissionspercapitaandthechangeinthetotalenergyintensityofeach countryintheperiod1990–2017.ThemajorityofthesecountriesaremembersoftheEUbutthedataforNorwayandTurkeyhavealsobeenaddedfor completeness.ItshouldberecognisedthattheUnitedKingdomisalso includedasanEUcountryasthedatarelatetoaperiodpriortoBREXIT. (ItshouldbenotedthatthedataforanumberofsmallerEUcountrieshave beenomittedforclarity;fulldetailsareavailableinthesourcereportwhich alsogivessomemoredetailforeachcountry.)ThefiguresforthewholeEU aregiveninthelastrow;theEUfiguresforthe%changesinGHG

l TheEuropeanEnvironment – StateandOutlook2020,EuropeanEnvironmentAgency,(2019),doi: https://doi.org/10.2800/96749,downloadablefrom https://eea.europa.eu/

Table1.3 GreenhousegasemissionsfromEUcountries.

Country

Austria84.5+6.29.6

Spain357.3+21.87.7

Sweden55.5 23.75.5

UK505.4

(Norway54.4+4.910.3

Thedatafortwonon-EUcountries,NorwayandTurkey,arealsoincludedinitalicsandthetotal emissionsfromtheEU(EU-28)areshowninboldfigures. SomedataconcerninggreenhousegasemissionsfromsomeEuropeancountries.

emissions,theGHGemissionspercapitaandthechangeintheenergyintensityoftheeconomyallowonetoseehoweachcountryhasperformedcomparedwiththeaverageresultforthewholeEU.ItcanbeseenthatBulgaria, theCzechRepublic,Germany,Ireland,Poland,Romania,Slovakiaandthe UKhaveperformedbetterthantheaverage.

Fig.1.6 showstheemissionsoftheprincipalgreenhousegasespersource type(givenasCO2 equivalentsinmillionsoftonsperyear)foralltheEU statesfortheperiod1990to2017and Table1.3 givessomeadditionalinformation.Mostofthecategoriesincludedinthefigureandtablehaveshown

Fig.1.6 EUgreenhouseemissionspersector.EquivalentCO2 emissionsfromdifferent Europeansectorsovertheperiod1990to2017. (Source:Europeenvironmentstateand Outlook2020(https://www.eea.europa.eu ).)

significantdecreasesinemissions.Aparticularlylargedecreaseoccurredin energysupply,thisbeingtheresultofincreaseduseofrenewablesourcesof energy,particularlywindandsolarpower.m Theintroductionofthesetechnologieshasbeenaccompaniedbyadecreaseintheuseofcoalcombustion forelectricityproduction.Therehasalsobeenasignificantdropinindustrial energyconsumption,duelargelytoimprovedefficienciesinindustrialprocessesandtoaswitchawayfromtheuseofcoalandoiltonaturalgasforthe supplyofenergy,thischangealsobeingassociatedwithimprovementsof technologies(Chapter3).SomeEUcountrieshavebeenattheforefront indecreasinggreenhousegasemissions.Forexample,ascanbeseenfrom Table1.3,Germany,originallyoneofthegreatestemittersofgreenhouse gasesinEurope,hadreduceditsemissionsby25.9%overtheperiodtoa levelof936milliontonsofCO2 equivalent.(Thishasbeenachievedpartly byasignificantdecreaseintheuseofligniteasafuel.)Unfortunately,however,somecountrieshadincreasedtheircontributions;forexample, Ireland’scontributionincreasedby12.9%to63.8milliontonsof CO2 equivalentandthatofCyprusincreasedby55.7%to10.0milliontons ofCO2 equivalent.Theseratherdifferentresultsappeartoberelatedtodifferencesinthestructuresofthedifferenteconomies.Forexample,Ireland hasverylittleheavyindustrybuthasastrongagriculturaleconomyaswellas

m Nuclearenergyisalsoconsideredtobearenewablesourceofenergy.Franceisparticularlyrelianton nuclearpower.Germany,ontheotherhand,hasdecidedtoclosedownallofitsnuclearreactorsandis wellonitswaytodoingso.OthercountriessuchasIrelandhaveneverhadnuclearfacilities.

largenumbersofnewhigh-technologycompaniesconsumingrelatively largequantitiesofenergy.

Table1.4 givesabreakdownofthechangesthathaveoccurredinthe emissionsofgreenhousegases(bothCO2 andothers)fortheperiod1990 to2017fromallEuropeancountries,thedatabeinggiveninmilliontons ofCO2 equivalents.Itcanbeseenthatroadtransportationcontinuestogive increasedemissionsasdorefrigerationandairconditioning.Inallothersectors,therehavebeensignificantreductions;particularlyimportantreductions havebeenfoundinresidentialheating,ironandsteelproduction,the manufacturingindustriesandpublicelectricityandheatproduction.Many oftheseimprovementswillbediscussedinsubsequentsectionsandchapters.

Fig.1.6 showsthattherehasbeenaslightlydecreasingcontributionto greenhouseemissionsfromagriculturesince1990.Theseemissions,mainly fromruminants(cattleandsheep)arestillsignificantandarethereforeacontinuingcauseforconcern,particularlyinIreland.Asimilarsetoffigureswill applygloballyalthoughtherewillbenationaldifferencesarisingfromdifferent

Table1.4 EUemissionspersource.