tidal energy in wales - c3wc3wales.org/wp-content/uploads/2012/10/tidalenergywalesv4.pdf ·...

The Urgency of Action on Human-Induced Climate Change TherecentDurbanConferenceoftheConferenceofPartiestotheClimateChangeConventionhasdemonstratedthatglobalemissionsofCO2intotheatmospherecontinuetoriseatabout+3%p.a.showinglittlesignofdiminishingalthoughthereisgeneralagreementthatwhatisrequiredareemissionsreductionsofincreasingseveritystartingwellbefore2020.Toachievethis,allcountriesneedurgentlytotakeactiontoharnessallpossiblerenewableenergysources.ThepurposeofthisnoteistopointoutthisurgencyandtocommendtheharnessingoftheTidesaroundWalesasanavailableandeffectivesourceofRenewableEnergyfortheUKthatcouldmorethanmeetWales’totalrequirementforelectricity.

Harnessing of Tidal Energy in Wales AdvantagespossessedbytheUKparticularlyaroundthecoastofWalesaresomeofthelargesttidesintheworldwithpotentialforsubstantialelectricitygeneration.Recentstudieshaveconsideredthefeasibilityofdifferentoptions.Urgentlyneedednowarefurtherstudiestodecideonthebestoptionsandproceedwiththeirrealisationassoonaspossible. ThatthelargetidesintheSevernEstuarytothesouthofWalesshouldbeharnessedtogenerateelectricity,firstconsideredinthe1930s,hasbeenaddressedinanumberofrecentstudies.PossibleoptionsincludeabarragefromWestontoCardifforseparatelagoonsindifferentlocationsintheestuary.Averagepoweroutputisestimatedatabout2GWwithonewaygeneration;twowaygenerationcouldsignificantlyincreasethatfigure. AlongthecoastofnorthWalesandincludingtheConwyandDeeestuaries,shallowwaterispresentforsomedistancefromthecoast.AnumberoflagoonscouldbebuiltbetweenAngleseyandtheWirralpeninsular(seefigure1)inwhichtidalenergycouldbegenerated.Recentworkhasshownthattheamountofenergygeneratedcanbemuchenhancedthroughgenerationonboththeebbandflowtidesandthroughpumpedstorageespeciallyduringperiodsofneaptides.Withtheseenhancementstheaveragepoweroutputhasbeenestimatedataround3GW,approximatelyequaltoWales’totalelectricityneeds. Becausethereareabout4hoursdifferenceinthetiming

ofthetidesinnorthandsouthWales,bycombiningoutputsfromthetworegions,tidalenergyisavailablethroughouttheday.Considerableflexibilityisavailableinthetimeprofileofenergygenerationthroughadjustmentsintheoutputflowsfromthebarrageorlagoonsorbyincorporatingperiodsofpumpedstorage.Synergy with Flood Defences AnumberofareasaroundWelshcoasts(e.g.northWaleseastofColwynBay)arethreatenedbylikelyincreasesinsealevelthiscenturyandwillrequirerenewedseadefences.Thebuildingoftidalrangesystemscouldassistwiththisandreducetherequirementsubstantially.Environmental Considerations Themainenvironmentalconsiderations,particularlyintheSevernEstuary,arelossofhabitat(e.g.mudflats)forbirdsandpossibledamagetofishintheturbines.Neitheraresufficientlystrongtoruleoutdetailedstudyofpossibleschemes.Itisessential,however,thattheseinclude

Conwy Bay Impoundment

Colwyn to OrmesImpoundment

ClwydImpoundment

LlandulasPilot

Hoylake & DeeImpoundment

Tidal Energy in Wales A note by Sir John Houghton, Chief Scientific Advisor, Climate Change Consortium of Wales (C3W), February 2012

Figure 1, not to scale, Map from Google

A schematic diagram of impoundments for power generation and coastal flood defenceafter Dr Stuart Anderson

Key points• The 5 North Wales coastal impoundments have a

potential average generation capacity of ~ 3GW.• Synergistic development of coastal flood defences and

power generation enhances economic benefits. • Total impounded area is approximately 700 Km2.

• Bi-directional, controlled phasing of generation adds the necessary flexibility to meet demand and increase efficiency.

• 70% of the impoundment barrages are aligned with the 5m seabed contour.

• There exists the possibility of a pumped storage power station with ~15GWh capacity at Penmaenmawr Mountain, a Brownfield coastal quarry that would link with the Conwy Bay Impoundment.

• The North Wales array would complement a Severn Barrage system due to tidal phase differences.

PenmaenmawrMountain

thoroughenvironmentalassessments.Regardingtheformerconsideration,nolossofbirdspeciesisanticipatedunderanyoftheschemesmentionedaboveandinanycasetherewillbelargechangesthiscenturyduetoclimatechangeandsealevelrisetowhichbirdswillneedtoadjust.Regardingthesecond,RollsRoyceisworkingonturbinedesignsthatwillminimizeimpactonfish.

Tidal Stream generationInadditiontopossibilitiesforTidalBarragesorlagoons,energycanalsobegeneratedfromTidalStreams.Thesearelocalregionswithstrongtidalflowsthatcanenergizeturbinesplacedintheflows.InWalessuchregionsexistparticularlyaroundAngleseyinthenorthwestandPembrokeshireinthesouthwest.

Economic BenefitTidalbarragesorlagoonsandtheassociatedinfrastructureareverylargeconstructionprojectsthatwillbringemploymentandeconomicbenefittotheareasinvolved.Ihavealreadymentionedthepotentialbenefittoseadefences.Otherdevelopmentprojectse.g.associatedwithtransportormaritimedevelopmentcouldalsobespawned.BecauseofthesizeofTidalRangeenergyschemesandtheirlargeassociatedeconomicandcommunityimpact,itisessentialthattheWelshAssemblyandtheUKgovernmentacceptanappropriatelevelofinvolvementandresponsibilityforthem.

Tidal energy in the rest of the UKTherearealsoareasintherestoftheUKwhereTidalRangeenergycanbeexploitedforinstanceestuaryschemesintheSolwayFirth,Tay,Forth,ThamesandtheWashwhichincludearangeofgenerationtimesthroughoutthe24hoursandwhereasignificantproportionofUKelectricitydemandcouldbegenerated.StrongTidalStreampossibilitiesoccurinScotlandespeciallyintheShetlands,theexploitationofwhichhasalreadybegun.AllthesepossibilitiesneedtobeinmindwhenconsideringthewiderimpactofWelshschemes,forinstanceonElectricityGridConnectionsetc.

The cost of Tidal Energy ThelargestpartofthecostofanyTidalRangeschemeistheinitialupfrontcostthatislarge-implyingapay-backperiodthatislongandvarieswiththefinancialassumptionsthataremadeincludingsupposeddiscountratesetc.However,underanyreasonableassumptionsthe‘pay-backperiod’isshortcomparedwiththeexpectedlifeoftheprojectof100yearsplus.Thereareinvestorswilling,evenkeen,toinvestinsuchprojectsprovidingthattheygetsomeguaranteesfromgovernmentregardingarrangements,suchasFIT,thatwillaffecttheshortertermandtheestimateoflikelypay-backperiod.IwasspeakingearlierthisyearatameetingonRenewableEnergyarrangedbyCitygroup,the4thlargest

bankintheworld,forsomeoftheirseniorstaffandanumberoftheirinvestors.Themainmessageofthediscussionatthatmeetingwastheneedforamoreeffectivedialoguebetweengovernment,businessandinvestorsthatwouldcreateclearandrobustarrangementsencouraginginvestmentinthewholerangeofrenewableenergies.Action NowIurgethatTidalEnergygenerationbegivenhighandurgentprioritywithinWalesforthefollowingreasons:1.TidalEnergycouldmakealargecontributionto

Wales’SustainabilityAgendaandtothereductionofgreenhousegasemissionsthatissourgentlyrequired.

2.TidalEnergycouldeasilyprovidemostofWales’Electricityneeds

3.ThenegativeImpactofTidalEnergyontheEnvironmentorAmenityissmallandverysmallcomparedwiththeoveralladvantages

4.Becauseoftheirsizeandtheirlonglife,thelongtermeconomicbenefitofTidalEnergyschemesislarge.Alsointheshortterm,thereissubstantialbenefittolocaleconomiesbecauseoftheirimpactonemployment,infrastructuredevelopmentandcommunityencouragement.

Start with the schemes in the NorthIhavearguedabovethatitisimportanttoconsidertogethertheproposedTidalschemesinbothnorthandsouthWales.Theschemesinthenorthhowever,aresimplertoaddressbecausetherearelesspotentialproblemseitherwiththeenvironmentorwithshippingandbecausethesynergywithseadefencesisalsobetterdefined.Further,therearelesspotentialcomplicationswiththelocationsofthenorthWaleslagoonsthanwitharrangementsinthemorecomplexSevernEstuary.ApilotschemebasednearLlandulashasalreadybeenproposedandwouldprovideanimportantandeffectivebasefortryingoutthelatestturbinetechnologyandoperationaluseoftwowaygenerationandofpumpedstorage.Thisneedstobestartedassoonaspossibletoprovideexperiencewith2-wayturbinesandoperationaltechnologyandtoassistinthereductionofuncertaintiessurroundingcurrentestimatesofperformance.

Diagramoftime-tide-phaseadvantageswithSevernBarrage

Above: Cross-section of barrage at turbine station. During construction, one caisson section at a time is closed off and pumped dry, allowing turbine installation. Sluice doors in adjacent turbine chambers are left open to allow tidal flow.

Above: Phase and height differences for tides at Cardiff (Blue), Conwy and Liverpool Bays (Green); Tremadog & Barmouth (Red) and Forth & Tay (Yellow). This demonstrates the complementary value of potential N. Wales tidal generation with the Severn Barrage.