The URL can be used to link to this page

Home My WebLink AboutJuneau Airport Ground Source Heat Pump Project Summary Report - Jan 2012 - REF Grant 2195359 ABriefReporttotheAlaskaEnergyAuthority OntheInstallationofaGeothermalHeatPumpSystemat JuneauInternationalAirport PreparedbyDouglasMurray,PEand CatherineFritz,JNUAirportArchitect January19,2012 Murray & Associates, P. C. Consulting Engineers PO Box 21081, Juneau, Alaska 99802-1081 (907) 780-6151 Fax: (907) 780-6182 Jeannie Johnson, Airport Manager 789-7821 Background. In2008,theJuneauInternationalAirport(JNU)receivedgrantfundingintheamountof$513,000to assistintheconstructionofageothermalheatpumpsystemfortheheating,cooling,andventilation needsintheairportterminal.ThisworkwaspartofamultiͲphaserenovationandexpansionofthe airportterminal.Theloopfieldwasdesignedbymechanicalengineer,DouglasMurray,PE.Thelifecycle costanalysis(basisofAEAgrantapplication)wasdevelopedcollaborativelybyMr.Murrayand mechanicalengineerJamesRehfeldt,PE. Thegeothermalloopfieldislocatedunderthepavementofthecommuterplaneairfieldramp.It consistsof108verticalboringstoadepthof350feeteach(fig1).Amixof88%waterand12%methanol circulatesthroughacontinuousundergroundloopofmorethan16milesofHDPEpiping.Thepiping entersthebuildingandisdistributedto31electricheatpumpsthatprovideheating,cooling,and ventilationtointeriorspaces,aswellasheattothebuilding’sfrontsidewalkthatpreventsbuildͲupof iceandsnow.Theheatpumpsaredigitallycontrolledtoefficientlyrespondtochangingairconditions. Constructionoftheloopfieldwascompletedinthefallof2009.Installationoftheheatpumpsinside thebuildingbeganinearly2010andcontinuedalongsideotherrenovationworkuntilMay,2011. PerformanceData. Thecompletedgeothermalheatpumpsystemhasnotyetbeenoperatingunderdesignconditionslong enoughtodrawsubstantiveconclusions.Additionally,nearlyhalfofthe96,000sq.ft.buildingareais notusingthenewgeothermalsystemandwillcontinuetobeservedbydieselboilersuntilfundscanbe obtainedtoreplacetheseolderportionsoftheterminal.Regardlessoftheseobstacles,datagatheredto dateshowpromisingevidenceofasuccessfulconversionfromtraditionaldieselfiredboilersto renewablegeothermalheatpumps.Preliminaryfindingsaredocumentedbelow. DieselFuelUsage: Adecreaseindieselfuelusagesinceinstallationofthegeothermalheatpumpsystemcanbeseeninfig. 3below.Fiscalyearsarehighlightedbycolorinordertoprovidetwomethodsbywhichtocompare dieselusagethroughseasonalcycles.Thegeothermalheatpumpinstallationwasfullyoperationalin May,2011,socalendaryear2011representsthebestavailableperiodofpostͲconstructiondata; Calendaryear2008representsafull12monthperiodpriortoanyinstalledheatpumps. Figure2.Schematicrenderingofclosedloopheatpump system.Imagefromwww.mcquay.com Figure1.VerticalboringsforJNUAirportloop field.ImagecourtesyofJNUstaff MONTH2008200920102011 GALLONSGALLONSGALLONSGALLONS JANUARY9636893999209307 FEBUARY97258462117761116 MARCH472210220107337788 APRIL10327298871003199 MAY6451115018415350 JUNE807578121908999 JULY1425722501900 AUGUST5659200012003600 SEPTEMBER8679460026384400 OCTOBER8227471249951377 NOVEMBER8314984433334209 DECEMBER84421016543919355 TOTALCalendar Year(JanͲDec) 89,682gal78,117gal59,835gal52,600gal TOTALFiscalYear (July1–June30) FY2009(grey) 80,317gal FY2010(aqua) 81,824gal FY2011(yellow) 46,216gal Figure3.DieselUsageatJNUTerminalpriorto,during,andaftergeothermalheatpumpinstallation. ElectricalUsage: Whiledieselusagehasdeclined,electricalusage,notedinfig.4below,hasincreased.Fiscalyearsare highlightedbycolorinordertoprovidetwomethodsbywhichtocompareelectricalusagethrough seasonalcycles.ThegeothermalheatpumpinstallationwasfullyoperationalinMay,2011,socalendar year2011representsthebestavailableperiodofpostͲconstructiondata;calendaryear2008represents afull12monthperiodpriortoanyinstalledheatpumps.Electricspacesheaterswereusedextensively fortemporaryheatduringconstructionfrom2009through2010. MONTH2008200920102011 KWHRKWHRKWHRKWHR JANUARY192,960191,840189,280232,800 FEBUARY209,280166,400175,840200,000 MARCH181,280161,440186,720233,760 APRIL175,520152,160201,760209,760 MAY153,760163,840186,880191,520 JUNE149,280151,680158,560197,440 JULY158,880166,400169,600186,400 AUGUST185,600182,880177,440184,160 SEPTEMBER170,080174,240165,920184,160 OCTOBER171,840168,960180,320180,160 NOVEMBER181,920180,960190,560218,720 DECEMBER163,200172,160220,480227,840 TOTALCalendar Year(JanͲDec) 2,093,600KWHR2,032,960KWHR2,203,360KWHR2,262,560KWHR TOTALFiscalYear (July1–June30) FY2009(grey) 2,018,880KWHR FY2010(aqua) 2,144,640KWHR FY2011(yellow) 2,369,600KWHR Figure4.ElectricalUsageatJNUTerminalpriorto,during,andaftergeothermalheatpumpinstallation. OperationalCostSavingsSummary. ThesavingsinfueloilbetweenCalendarYear2008(preͲconstruction)andCalendarYear2011(postͲ construction)is37,082gallons.Theaveragecostoffueloildiesel#2inJuneauduringtheperiodofthis analysisis$3.52pergallon.Therefore,thecostoffueloilsavedbetweenCalendarYear2008and CalendarYear2011isapproximately$130,529. Theairportterminalprojectaddedapproximately12,000sq.ft.ofnewareatothebuilding.The differenceinelectricalusagebetweenCalendarYear2008(preͲconstruction)andCalendarYear(postͲ constructionthatincludes12,000sq.ft.buildingexpansion)isapproximately168,960KWHR.The electricallocalcost,includingdemandcharges,usedforpurposesofthisanalysisis$0.092perKWHR. Therefore,theadditionalcostofelectricityfortheairportterminalisapproximately$15,544. Subtractingtheadditionalelectricalusagecostfromthefueloilcostsavingsresultsin$114,985indirect annualfuelcostsavingsfortheJuneauInternationalAirportfacilitywiththeinstallationoftheground sourceheatpumpsystem. Anothersignificantbenefitthattheairporthasseenisthedecreaseinoperationscostsduetothe snowmeltsystem.Thisisanewsystem,andwhileitdemandssignificantenergytooperate,thesafety andpassengercomfortissuesareverypositive.ThesnowmeltsystemisenergizedbythreewaterͲtoͲ waterelectricheatpumpsthatareintegrallytiedtothegeothermalloopfield.Whilenotanalyzedin detail,itisexpectedthatoperatingthissystembyanequivalentdieselenergysourcewouldhavemade theinstallationcostprohibitivefortheairport’sannualoperatingbudget.Thegeothermalsnowmelt systemsavingsovertraditionalsnowremovaloperationsisapproximately$10,000peryearinstaff labor,and$1,000inequipmentandsupplies. Note: Thisoperationalcostsavingssummaryislimitedinscope.Afullenergyusageanalysisofpreandpost constructionconditionswouldrequiremoreextensiveinvestigationofelectricalconsumptionfrom computers,lights,andotherelectricequipmentusedthroughoutthefacility,aswellastrendingdata fromthecontrolsystemoperationforallgroundsourceequipment.Inordertoproduceamore accuratecalculation,informationwouldberequiredonhowofteneachwaterͲtoͲairheatpump operatesincoolingmodeandhowoftenitoperatesinheatingmode.Additionalinformationthat indicatesthepercentageofuseofeachofthetwosystemcirculationpumpswouldberequired,aswell. AsimilarusagequestionariseswiththewaterͲtoͲwaterheatpumpsduringshouldermonths(ie transitionfromtimesofsnowandnosnow)whenheatpumpsareintermittentlyinoperation,rather thanhavingallthreeinfulloperation24/7,astheroughelectricalusagecalculationimplies. FurtherAnalysisofadditionaloperationalsavingsisexpectedtobedoneastheairportimplements energyconservationmeasuresrecommendedfromarecentenergyaudit,andperformsongoingminor renovationprojectsintheterminalbuilding.Mostnotably,astheairportlearnsmoreaboutthe intricaciesofthegeothermalheatpumpsystem,itisexpectedthatadditionalsavingswillberealized throughmoredetailedcontrolofheatpumpsetpointsandusagepatterns.Ofparticularinterestisthe MayͲOctoberperiod(whensnowmeltsystemisnotinoperation)whenthegroundsourcesystem averagepowerconsumptiondropssignificantlyasthebuilding’sheatingandcoolingneedsare “balanced”andthesystemdoesnotrequirerecirculationthroughtheoutsideloopfield. Otheroperationalandhumancomfortbenefitsofthegeothermalheatpumpsystemarestillbeing realized,nottheleastofwhichisthebuilding’snewabilitytoprovidecooling(airconditioning) throughouttheoccupiedspaceswhichdidnotexistbefore.