March/April2009‐TechnologyReview‐PublishedbyMITsince1899AZero­EmissionsCityintheDesertOil‐richAbuDhabiisbuildingagreenmetropolis.Shouldtherestoftheworldcare?ByKevinBullis

Thefirsthintsoftheprojectarevisible.Awhitewallstretchesthroughthedesert,likeachalklineonadustyplayingfield.Abuswithdarkenedwindowsstirsalowcloud,ferryingworkerspastaclusterofsteelcranes,twoportabledrillingrigs,andastandofconcretecolumnssproutingrust‐coloredrebar.Atallwirefenceguardsrowsofsolarpanelsmountedonconcretepads.Theconstructionisthestartofavastexperiment,anattempttocreatetheworld'sfirstcar‐free,zero‐carbon‐dioxide‐emissions,zero‐wastecity.Duetobecompletedin2016,thecityisthecenter‐pieceoftheMasdarInitiative,a$15billioninvestmentbythegovernmentofAbuDhabi,whichispartoftheUnitedArabEmirates.Thenewdevelopment,beingbuiltontheoutskirtsofAbuDhabicity,willrunalmostentirelyonenergyfromthesunandwillusejust20percentasmuchpowerasaconventionalcityofsimilarsize.Garbagewillbesortedandrecycledorusedforcompost;sewagewillbeprocessedintofuel.Concretecolumnswillliftthecitysevenmetersofftheground,creatingspaceunderneathforanetworkofautomatedelectrictransportsthatwillreplacecars.Plannerspredictthatthedevelopmentwillattract1,500clean‐techbusinesses,rangingfromlargeinternationalcorporationstostartups,and‐‐eventually‐‐some50,000residents.Thecitywillbeanoasisofrenewableenergyinacountryoffivemillion,maderichbyoil,thatconsumesthemostnaturalresourcespercapitaintheworld.Seenoneway,it'sjustthelatestostentatiousprojectinacountrythat'sbeendefinedbythem.Indeed,theUAEisalreadyhometotheworld'stallestbuildingandanenormousindoorskifacilitythatfeaturesa200‐meter‐longblack‐diamondslope.Real‐estatedevelopershavedredgedcoralandsandfromtheseafloor,pilingitupinthePersianGulftocreateislandsintheshapeofpalmtreesandamapoftheworld.

Yetmanyexpertsareoptimisticthatthecitycanbecomeatestbedfornewapproachestotheengineeringandarchitecturalproblemsinvolvedincreatingenvironmentallysustainablecities.Althougharchitectshavealreadydesignedandbuildersconstructedmanysmallzero‐emissionsresidencesandcommercialbuildings,projectsinvolvinglarge,multi‐usecommercialbuildingshavefallenshortofexpectations,usingtoomuchenergyorfailingtogenerateenough.Partoftheproblemisthegrowingcomplexitythatcomeswithscale,saysJ.MichaelMcQuade,seniorvicepresidentofscienceandtechnologyatUnitedTechnologiesinHartford,CT;today'sdesignsoftwarehasn'tbeenabletohandleit.ButMasdarCity,itselfdevelopedwiththehelpof

extensivemodeling,willbewiredfromthebeginningtocollectdatathatcouldprovevaluablefordevelopingbettermodels.Thatinformationcouldmakefuturezero‐emissionscitiescheaperandeasiertobuild.

Andthedevelopmentismeanttomakemoney,notjustintroducenewtechnology."WewantMasdarCitytobeprofitable,notjustasunkcost,"saidKhaledAwad,theproject'sdirectorofpropertydevelopment,atahugereal‐estateexhibitioninDubailastfall."Ifitisnotprofitableasareal‐estatedevelopment,itisnotsustainable."Yetifitis,itmaybereplicable.

"Ifenvironmentalengineers,bygainingexperiencefrombuildingthiswildcity,becomemuchmoreproductiveatbuildingthenextcity,thisstartstomovefrombeingsciencefictiontosomethingHoustonwouldadopt,"saysMatthewKahn,aprofessorofeconomicsattheUniversityofCalifornia,LosAngeles.GilFriend,CEOofNaturalLogic,asustainable‐designcompanybasedinBerkeley,CA,agrees."IseeMasdarontheonehandasaplaygroundfortherich,"hesays,"andontheotherhandasanR&Dopportunitytodeployandtestouttechnologythat,ifthingsgowell,willshowupinothercities."

Ofcourse,muchofwhat'slearnedfromMasdarwon'tapplyoutsidetheincrediblyhotandsunnycoastofthePersianGulf.AsiteinGermany,whichwouldn'tgetasmuchsunlight,couldn'trelyasheavilyonsolarenergy.AsiteinSanFranciscomightnotneedairconditioning,makinginformationaboutadvancedcoolingsystemslessrelevant.Butiftheprojectreachesitsenvironmentalgoals,itwillattheveryleastshowthatsuchcitiescanbebuilt."Peoplesay,'Gee,thatwouldbegreat.Thatwouldbeagoodidea,butobviouslyit'snotpossible,'"Friendsays."Onceyoucanpointatsomething,ittakesawayalotofthosearguments."

Energysurplus:Masdarheadquarters,showninanarchitecturalrendering,isdesignedtogeneratemorerenewableelectricitythanitconsumes;itwouldbethefirstlarge‐scale,multi‐usebuildingtodoso.Credit:©AdrianSmith+GordonGillArchitecture

BreakingGroundTheMasdarInitiativeispartofanambitiousplantotransformaresource‐basedeconomy‐‐thethird‐largestexporterofoilintheworld‐‐intoonebasedonknowledgeandexpertise.ThenameMasdarcomesfromtheArabicwordfor"source,"andtheplanistomakeAbuDhabitheSiliconValleyofalternativeenergy:asourceoftalent,patents,andstartupsintheveryindustrythatcouldonedaychallengethesupremacyofoil.It'sadauntingchallengetosaytheleast,especiallyforaregionthat,accordingtoAwad,"hasn'tbeenknownforinnovationforathousandyears."

Thecitywasconceivedasatax‐freezonemeanttoattractclean‐technologycompanies,largelyfromothercountries.(Thefirsttenant,GeneralElectric,planstobuilda4,000‐square‐meterfacility.)TheMasdarInstitute,thefirstpartofthecitytobebuilt,ismeanttobewhatStanfordUniversityistoSiliconValley.DevelopedincollaborationwithMIT,whichorganizedthecurriculumandishelpingtoselectandtrainthefaculty,theinstitutewillbeagraduateresearchschool,offeringmaster'sdegreesand,eventually,PhDs.Itsfirstclassof100studentswillstartcoursesthisfall.Andifgraduatesdeveloppromisingideasandstartcompanies,theycanlooktotheMasdarInitiativeforcapital.Ofthe$15billionthegovernmenthassetasidesofarfortheinitiative,onlyabout$4billionisdesignatedasseedmoneyforbuildingthecity's

infrastructure.(Thecityisexpectedtocostatotalof$22billion,theresttocomefromoutsideinvestors.)Theremaining$11billionisearmarkedforarangeofinvestments;projectssofarincludeasolar‐cellfactoryinGermany,anoffshorewindfarmintheUnitedKingdom,andeffortstoreducecarbonemissionsinNigeria.

Still,thecityisthemostvisiblepartoftheinitiative.Itisbyfarthelargestzero‐emissionsandzero‐wasteprojectintheworld,accordingtoseveralexperts.(Alarger"eco‐city"developmentnearShanghaidoesn'taspiretozeroemissions.)Effortselsewherehavesofarbeenlimitedtosmalltomoderate‐sizedbuildingsandsmallcommunities,likeaseriesofefficientrowhousesfor250peopleinWallington,SouthLondon.Oneofthemostambitiouszero‐emissionsbuildingstodate,theLewisCenteratOberlinCollegeinOhio,has1,263squaremetersoffloorspace.MasdarCitywillcoversixsquarekilometers.Itsheadquartersalone,whichwillincludeofficesaswellasretailandculturalspace,willoccupyan89,500‐square‐meterstructure.

Adetailedmasterplanforthecityiscomplete,asareplansforthefirstbuildings:theMasdarInstituteandtheheadquarters.Thecity‐‐whichwillincludeapartmentsandlaboratories,butalsofactories,movietheaters,cafés,schools,firestations,andsoon‐‐isintendedtogenerateasmuchelectricityasituses.Itswaterwillberecycledtosavetheenergycostsofdesalination.Vacuumtubesunderthecitywilltransportgarbagetoacentrallocation,whereitwillbesorted,andasmuchaspossiblewillberecycled.Trashthatcan'tberecycledwillbeconvertedtoenergythroughagasificationprocessandtheleftoversincorporatedintobuildingmaterials.Sewagewillbetreatedandsomeofitprocessedintoadryrenewablefuelforgeneratingelectricity.Thetransportationsystemwillincludealight‐raillinelinkingthedevelopmenttodowntownAbuDhabiandtheairport,aswellasapersonalrapid‐transit(PRT)systemwithstationsthroughoutthecity.ThePRT,asystemofautomatedelectricvehicles,willconnectpeopletotheraillineordeliverthemtoparkinggaragesoutsidethecity.

Asistypicalforzero‐emissionsprojectstodate,thecitywillneedtorelyinpartonfossilfuels‐‐bothduringconstructionandforpoweratnight,whenitssolarpanelswon'tbeproducinganyelectricity.Thegoalisactuallybestdescribedaszeronetcarbondioxideemissions:toreachthezero‐emissionstarget,thedeveloperswillturntoasystemofcarboncredits.Asthecityisbeingbuilt,a10‐megawattarrayofsolarpanelswilldeliverpowertonearbyAbuDhabicity,reducingdemandforelectricityfromlocalnatural‐gas‐firedpowerplantsduringtheday.Thecarbonemissionssavedwilloffsettheemissionsproducedatnight,whenMasdardrawspowerfromthosesamenatural‐gasplants.Thissolararray,andadditionalpanelsthatwillbeinstalledasconstructioncontinuesandelectricitydemandgrows,willalsooffsetthecarbonemissionsfromconstructionequipment,fromtheprocessesusedtomakebuildingmaterialssuchasconcrete,andevenfromconsultants'flightsintoAbuDhabifromcitiesaroundtheworld.

Sofar,thedevelopershavebeenaccountingfor"justabouteverything,"saysPooranDesai,cofounderofBioRegional,aBritishcompanythathelpeddevelopthezero‐emissionsprojectinLondonandhasconsultedforMasdar."Idon'tknowofanyotherprojectthathasbeenasthoroughintermsofitscarbonmonitoring,"saysDesai."They'rehuntingdowneverymoleculeofcarbondioxide."

Thebuilding’sstructuralcones,whichsupportaroofladenwithsolarpanels,willprovidelightandventilation.Thepondhelpscooltheair.Credit:©AdrianSmith+GordonGillArchitecture

TheMasterPlanDubaiisasprawling,car‐dominatedcityaboutanhour'sdrivefromAbuDhabicity.Skyscrapersstretchalonga12‐lanehighway,SheikhZayedRoad.Sunlightheatstheunshadedareasto46°Cinthesummer.ButthereareafewplacesinDubaiwhereapersoncanwalkoutdoorsinthemiddleofthedaywithoutriskingheatstroke,andallareartifactsofthepast.Therearethecoveredsouks,shadedmarketplaces.AndthereisahistoricdistrictcalledtheBastakiya,whichpreservessomeofthearchitecturethatprotectedlocalsfromtheheatandhumiditybeforethearrivalofairconditioning.Thehousesandshopshavethickwallsmadeofdriedcoralandgypsumthatabsorbheatduringtheday,releasingitslowlyatnight.Becausethebuildingsarepackedcloselytogether,theyshadebotheachotherandthenarrowpassagesbetweenthem.Thepassagesfunnelbreezes,coolingthebuildingsfurther.WhenGerardEvenden,aseniorpartnerattheBritishfirmFosterandPartners,begantomakethemasterplanforMasdarCity,helookedtosuchtraditionaldesignsforwaystosaveenergy.Sincethecitywilldependalmostentirelyonelectricityfromsolarpower,whichisfivetimesthepriceofelectricityfromthelocalgrid,thecityneedstoberoughlyfivetimesasenergyefficientascompetingdevelopmentsnearby.OneofthefirstthingsEvendendidwassubtractcars:withthehighwaysgone,thecity'sbuildingscouldbeseparatedbypassagesjust7to12meterswide,closeenoughtoshadeeachotheryetfarenoughaparttoletinindirectlight.That'sacheapwaytoreducetheneedfornotonlyairconditioningbutelectriclighting,thelargestdrainonelectricityincommercialbuildings.Insulationischeap,too:intheMasdarInstitute,Evendenplanstouse30‐centimeter‐thickinsulationtokeepouttheheat.He'salsoincorporating"skins"ofcopperfoilthatreflectlightandconductheatawayfromthebuildings.Thefoilwillbeprotectedfromthedesertdustbyaself‐cleaningTeflon‐likeplastic.Toreducetheneedforenergy‐intensivedesalination,Evenden'sdesignwillcutwaterconsumptionby75percentthroughrecycling,low‐flowfixtures,andwaterlessurinals.

Asmallfractionoftheenergythat'sstillneededtorunthecitywillcomefromwaste‐basedfuelandperhapsgeothermalpower.Therestwillcomefromthesun‐‐butnotallofitthroughexpensivephotovoltaics,whichconvertsunlightintoelectricity.Muchcheaperdevicesthatconcentrateheatfromthesunwillheatwaterandrunatypeofairconditionercalledanabsorptionchiller.(Thisisthesamekindoftechnologythatisusednowinpropane‐poweredrefrigerators.)

Intheory,itshouldallwork.Butinpractice,evenmuchlessambitiousprojectshavefailed.OberlinCollege'sLewisCenterfeaturesmanyofthesameelementsofenergy‐efficientdesign:thickinsulation,naturalventilationwithheatexchangers,plentyofwindowstooffsettheneedforelectriclighting,andheatpumpsratherthanconventionalfurnaces.A60‐kilowattarrayofsolarpanelsonitsroofwassupposedtoproduceasmuchelectricityoverthecourseofayearasthebuildingconsumes.Yetthebuildinginitiallyusedtoomuchenergy,andthesolarpanelswerenotadequate.Toachievezeronetenergy,thecollegehadtoinstallanextrasolararraynearby,morethantriplingthetotalpowerproduction.Itaddedoveramilliondollarstoanalreadyexpensivebuilding,estimatesJohnScofield,aphysicsprofessoratOberlinwhohaspublishedadetailedanalysisofthebuilding'sperformance.

Ingeneral,architectsfindthatpredictinghowenergy‐efficientsystemswillinteractgetsmuchharderasbuildingsgetbigger.Inbuildingsdesignedtotakeadvantageofnaturallight,forexample,designerscaninstallsensorstoautomaticallyswitchbulbsoffwhenenoughlightcomesinfromoutside.Butlights

turningonoroffinonesensingzonemayaffectthesensorsinanother.Insomebuildingsthishascreatedafeedbackloopthatmakeslightscycleonandoffannoyingly.

Neighboringheatingandcoolingzonescanalsoaffectoneanothertocreatecomplexandunpredictablefeedbackloops,especiallyasthenumberofzonesincreases.UnitedTechnologies'J.MichaelMcQuaderecallswhathappenedwhenhiscompanydesignedwhatwassupposedtobeanintelligentheating,ventilation,andair‐conditioningmanagementsystemforanewbuildinginParis.Thesystemwasdesignedtocoördinate3,000differentzones."Whenthatbuildingwasfirstputtogether,itwasasignificantenergyconsumer,andittookarevampoftheintegratedcontrolsystemstogetitright,"McQuadesays.

Ifzero‐emissionsbuildingsaretobeeconomical,Scofieldsays,thedesignswillhaveworkfromthestart."Ifyoudon'tgetitright,"hesays,pointingtothefiascoatOberlin,"everycorrectionyoumakeissomuchmorecostlythangettingitrightthefirsttime."

PersonalTransitMasdarCitywillberaisedonconcretestiltstomakeroomforapersonalrapid‐transit(PRT)systemthatwillreplacebusesandtrainswithsmallervehiclesdesignedforfourpeople.Masdar'splannersexpectthesystemtouselessenergythanconventionalmasstransit,andtheysayitwillbemoreconvenient,too.

InaPRTsystem,severalsmallvehicles,oftencalledpods,arekeptwaitingateachstation.Anindividualorasmallgroupboardsoneandselectsadestination;thepodproceedsautomaticallytothedestinationwithoutstopping.Inatypicaldesign,eachvehicleresemblesabattery‐poweredgolfcart,onlyit'scompletelyenclosedandsomewhatbigger‐‐anditlacksasteeringwheel.Thevehiclefollowsatrack,whichisconnectedtostationsbyon‐rampsandoff‐ramps,andacomputercontrolshowthepodsenterandexitthestations:therampsallowindividualpodstomakestopswhileotherscontinuealongthemaintrackattopspeeds.Simulationssuggestthatthesystemscouldrunwithaslittleashalfasecondbetweenvehicles.

ButalthoughPRTslookpromising,theyhaven'tcaughton.That'sinpartbecauseanearlyPRT‐likesystembuiltinthe1970sinMorgantown,WV,gavetheideaabadname,saysJerrySchneider,anemeritusprofessorofurbanplanningandcivilengineeringattheUniversityofWashingtoninSeattleandalongtimeadvocateofPRTs."Peoplewouldgetonthevehiclesandtheywouldn'tstop,"Schneidersaysofthesystem,atransitlinewithautomatedcarsforabout20people.Technologyhasimprovedsincethen,hesays,buttherehasn'tbeenasignificantreal‐worlddemonstrationoftheupdatedsystems.

Twodemonstrationprogramsareontheway.Thefirst,whichwilltransportpassengerstoanewterminalatHeathrowInternationalAirportnearLondon,willopenlaterthisyear.Testsofthatsystemarealreadyunderway.AndthefirststageofthesystematMasdarCity,tobebuiltbytheDutchfirm2GetThere,isscheduledtobeinplacefortheopeningoftheMasdarInstitutethisfall.

Shadylane:Solarpanelsontheroofsprovidesunprotectioninpublicspacesbetweenbuildings.Credit:©AdrianSmith+GordonGillArchitecture

TheTestBedSameerAbu‐Zaidisn'tbreakingasweat.It's39°Cwith74percenthumidity,buthesaysit'saniceday‐‐muchcoolerthanthesummerinAbuDhabi,whentemperaturescanreach49°C.Abu‐Zaid,who'soriginallyfromJordanandwasmostrecentlyamanageratasemiconductorequipmentmanufacturerinSiliconValley,willmanageMasdarCity'spoweranddistributioninfrastructure."Allofthesemoduleshavebeentestedatthefactories,"hesaysashegivesatourofoneofthefirstvisiblesignsofthecity,atestsitewherehe'sputting41arraysofsolarpanelsfromvariousmanufacturersthroughtheirpaces."Buttheyhavebeentestedunderstandardtestconditions:1,000wattspermetersquared,25°C.Niceair‐conditionedspace.Itistotallydifferenthere."

Dustfromthedesertquicklycoatsthepanels,effectivelydimmingthelightthatreachesthem.Abu‐Zaidhaslearnedthatjustfourmonthsofdustreducestheoutputofthesolararraysbymorethan20percent‐‐informationhe'llusetodecidehowoftentowashthepanels,balancingpowerlossagainstwaterconsumption.

Anotherproblemistheheat.Solarpanels'darksurfacesabsorbsunlight,raisingtheirtemperaturetoasmuchas80°C.Theheataffectssomesolar‐celltechnologiesmorethanothers.Someofthemostefficientsolarpanelsalsoproducelesspowerwhentheygethot.Becauseofthesetrade‐offs,it'snotobviouswhichpanelswillworkbestattheMasdarsite,Abu‐Zaidsays.Atthetestplot,sensorstrackhowmuchvariouspanelsheatup,howeffectivedifferentcoolingstrategiesare,andhowpoweroutputchangeswithtemperature,amongotherfactors.

Suchdatagatheringwillcontinueasthecitygrows.Itsdesignersandengineerswillmeasurebothenergyconsumptionandenergyproduction.Theywilltrackwaterconsumptiondowntotheindividualfixture.AtMasdarheadquarters,designersmayuseRFIDtagsinsecuritybadgestogatherinformationontheway‐peopleusewaterandenergy.Suchmeasurementswillallowdesignersandengineerstocomparetherealperformanceofthecitywiththeperformancepredictedbylaboratorytestsandsimulations.RealityCheckIntheearly1960s,whiletheUnitedStateswasrushingtoputamanonthemoon,electricfansandlightswerestillunheard‐ofinAbuDhabi,accordingtoMohammedAlFahim,anativeoftheemiratewhohaswrittenararehistoryoftheplace.Thatwasnotlongafteroilwasdiscoveredthere,andwellbeforethemoneystartedflowing.AlFahimisfromoneofthewealthiestfamiliesinthearea,yetbothhissisterandlaterhismotherdiedbecauseofalackofbasichealthcare.NowlifeexpectancyinAbuDhabiisvirtuallythesameasintheUnitedStates.Before,thelocalssurvivedonwaterfrombrackishwells;nowtheydrinkfreshwaterfromnewdesalinationplants.Thefragileandhighlyflammablepalm‐frondhutsthathousedmostpeoplehavebeenreplacedbygleamingglass‐and‐steelskyscrapers.Inmanyways,thedevelopmentofAbuDhabioverthelastfewdecadeshasreflectedafreneticefforttocatchupwiththedevelopedworld.Now,becauseofprojectssuchasMasdarCity,theemiratehasachancetoraceahead.Butintermsofurbandevelopment,itappearstobeverymuchatacrossroads.Inafewyears,whilethecitizensofMasdarCitywillbepinchingkilowatt‐hoursandusingwaterlessurinals,go‐cartswillbescreamingaroundanewtrackataFerrarithemeparknearby,kidswillbeshriekingas

theyplummetdownwaterslidesatanewwaterpark,andmassiveairconditionerswillberoaringastheycoolanew700‐storesupermall.It'sallpartofa2,500‐hectaredevelopmentthatwilldwarfthe640‐hectareMasdarCity.ThetwodevelopmentsarecompetingvisionsforthefutureofAbuDhabi.IftheMasdarprojectdoesn'tjustifyitselffinancially,itcouldindeedbejustagreenplaygroundfortherich,anenvironmentalthemeparkthatislargelyirrelevantforthedevelopmentofsustainabletechnologyonabroaderscale.Butifitisprofitable,itcouldbeadrivingforceforsustainableurbandesign.Thentheoil‐richdevelopersintheUAEandelsewheremighthaveareasontobuildmoregreencitiesandskipconstructinganotherskislopeinthedesert.Anddevelopersworldwidewillfollow.KevinBullisisTechnologyReview'sEnergyEditor.