District heating systems based on low-carbon energy technologies in Mediterranean areas

1Introduction Energysupplysafetyisoneofthegreatchallengesforthecomingdecades.By2040,anincreaseinenergydemandof48%isexpectedwithagreatcontributionofcountriesasChinaandIndia[1].Thebuildingsectorisoneofthemainenergyconsumers,with 20%ofthecurrenttotalenergyconsumption,andwithanexpectedincreaseof1.4%/year,from2012to2040[1]. Abigpartofthisincreasecomesfromurbanareas,butenergyconsumptioninruralareasalsorequiresspecificconsiderations.Mostruralareasdonothavenaturalgasnetworks,theirthermalenergyproductionbeingbasedongasoilcombustion[2],witha higherprice.Moreover,inmanycases,theseruralareasarelocatedatclimateconditions,i.e.:higheraltitudes,closetomountains,withahighheatingenergydemand.Byothersideinruralareasfrequentlythereisbiomassenergyresourceavailable.Whenavailable,its correctusefavoursthesocial,environmentalandeconomicsustainabilityoftheregion.Inmanycasesruralareashavelowerpercapitaincomesandhigherlevelsofunemployment[3,4].Thus,theusualcombinationofhigherenergydemandrequirements,highercostof energyandreducedincomes,impliesahigherriskofenergypovertyforcitizenslivinginruralareasthanforcitizensofurbanareas. Districtheating(DH)systemsareconsideredapromisingwaytoincreaseenergyefficiencyinthermalpowerproduction[5].DHsystemsarebasedonacentralpowerproductionsourcethatsuppliesenergytoseveralbuildingsconnectedbyaheatingnetwork. WhenDHsystemsarepoweredbyrenewableenergies,asrenewablebiomass,thegreenhousegasesemissionsarehighlyreduced,byboththelowerenvironmentalimpactoftheserenewablefuelresourcesevaluatedalongtheirwholelifecycle,andthehigher efficiencyofDHsystemscomparedwithindividualheatingsystems[6].Inaddition,theuseofcentralizedgenerationthermalsystemsallowsamoreeffectivecontrolofpollutantsthantheobtainedinindividualboilers.TheEuropeanDirective2012/27/EU[7]promotes energyefficiency,inwhichthedistrictheatingsystemsplayanimportantrole.Today,therearearound6000DHfacilitiesinEurope,withahigherpenetrationofthetechnologyinNorthandNortheastEurope[8].InSpain,thedeploymentofDHsystemsisbecominga reality,with306facilities,althoughalltheseplantsonlypresentaninstalledthermalpowercapacityof893MWth[9].Inrecentyears,manyauthorshavebeeninvestigatingDHsystemsfromseveralperspectives:technicaldevelopment[10–12],methodologiestoevaluate thepotentialofDHfacilities[13,14],and,policiestofacilitatethedeploymentofDHsystems[15–17].Furthermore,severalongoingresearchprojectsthroughouttheworldarefocusedonadvancedDHsystems[18–20]. Amongrenewableenergies,biomass,solarandgeothermalenergiesareparticularlysuitableforintegrationintoDHsystems[21].Thebiomasspriceishighlydependentontheresourcepotentialavailabilityinareasnearthefacility[22,23],anditsuseasan Potentialofbiomassdistrictheatingsystemsinruralareas V.M.Solteroa,∗ vmsolte[email protected]s R.Chacarteguib C.Ortizc R.Velázquezb aEscuelaPolitécnicaSuperior,UniversidaddeSevilla,41011,Sevilla,Spain bEscuelaTécnicaSuperiordeIngeniería,UniversidaddeSevilla,CaminodelosDescubrimientoss/n,41092,Sevilla,Spain cFacultaddeFísica,UniversidaddeSevilla,AvenidaReinaMercedess/n,41012,Sevilla,Spain ∗Correspondingauthor. Abstract Biomassdistrictheatingsystemsareapromisingwaytoincreasethermalefficiencyinruralareas.Theseareashavespecificcharacteristics,suchasarelativelowlinearheatdensityandproximitytobiomassresources.Generally,ruralareasshow higherlevelsofenergypovertythanurbanareasandahighernumberofpartiallyusedorunoccupieddwellings.Thesefactorsgreatlyaffecttheenergyprovidedbyadistrictheatingsystemandshouldthereforebeproperlyassessedwhendesigninga sustainablefacility.Thismanuscriptdevelopsamethodologyforimplementingbiomassdistrictheatingfacilitiesinruralareas,takingintoaccounttheirspecificcharacteristics.Asacasestudy,themethodologyisappliedto499ruralmunicipalitieswitha populationabove1500inhabitantsinthecontinentalregionofSpain.Resultsshowapotentialfor154biomassdistrictheatingsystemswithaninternalrateofreturnabove5%,and31systemsabove10%.Ontheotherhand,onlythreedistrictheatingsystems areclassifiedasnon-profitable.ThemassiveimplantationofthesesystemsintheregionunderstudyreduceCO2emissionsfromfossilfuelsin5.4milliontonsperyearandwouldimplyandimportantimpulsetolocaleconomy. energyresourcewithinaframeworkofenvironmentalplanning,contributestoreducingwildfirerisksintheforest–urbanareas[24]. Oneofthemostusedindicatorsforpre-evaluationofdistrictheatingsystemsviabilityisthelinearheatdensity(LHD)[25].Reidhavetal.[15]setalinearheatdensitythresholdvalueof0.56 MWh/mfortheeconomicviabilityofthefacility.Theyalsoobtainedthat valuesofLHDhigherthan1.1 MWh/mdonotimprovethereturnontheinvestment. Nevertheless,inthecaseofnon-homogenousurbanareas(asinruralareas),theusualmethodofestimatingtheLHDmaybeinaccurateifspecificissuesarenotincludedintheevaluation.DHsystemsinruralareashaveadditionalchallengessuchaslower buildingdensitiesandtherequirementformoreextendedpipenetworks.InthecaseofbiomassDH(BioDH)systems,theLHDcanbeusedtonotonlyanalysethepotentialforDH,butalsothebiomassprice,whichvarieswidelybasedonavailability,biomasstypeand distancetotheresources. ThispaperpresentsanewmethodologydevelopedtoevaluatethepotentialofBioDHinruralareasfromaglobalperspective.Itintroducesasetoffactorsthatsignificantlyaffecttotheimplantationofheatingnetworksinruralareas,suchasenergypovertyand thenumberofsecondresidences.Inaddition,distributiontypologyofbuildings(blocks)andagedistributionofbuildingsareincluded.TheintroductionofthesecorrectionfactorssignificantlymodifiesthecriteriaforDHinvestment. Thepaperisstructuredasfollow:first,theproposedmethodologyisdescribed,highlightingthemainfactorsthatinfluenceruralBioDHsystems.Then,themethodologyisapplied,ascasestudy,toevaluatetheuseofbiomassdistrictheatingnetworksin499 ruralmunicipalitiesinSpain.Thisapplicationshowsthehighreproducibilityofthemethodology.Theresultsshowthat496(99.4%)oftheproposedDHsystemsareprofitable,ofwhich31systemshaveaninvestmentratereturn(IRR)above10%. 2Methodology Thissectiondescribesatop-down/bottom-upmethodologyforevaluatingtheprofitability,andthesocioeconomicandenvironmentalimpactsofBioDHsystems.Fig.1showsthestagesthatcomprisestheproposedmethodology.Itisdevelopedunderthe followingassumptions[14]:i)energycostfortheenduserislowerwiththeBioDHsystem;ii)NosubsidiesareconsideredfortheBioDHprojects,whichmustbeviableandself-sustainable;iii)BioDHsystemswilluselocalbiomassresourcesasfaraspossible, consideringsustainableforestexploitationandmanagement;and,iv)BioDHimprovesenvironmentalperformanceoftheheatingtechnologiesinuseinthemunicipality.UnliketheworkpresentedbySolteroetal.[14]whichisfocusedoncombinedheatandpower systemsinlocationswithnaturalgasnetworks,withrepeatabledemandandresourcepatterns,themethodologyproposedinthepresentworkincludesspecificstepsintheevaluationforbiomass,suchaslocalbiomassresourceanalysis,aswellasimprovedstepstofits theheatdemandestimationtothespecificcharacteristicsofeachruralarea.Itisbasedonforestrybiomassresource,althoughithavecommonpointsanddifferenceswithagricultureresiduesexploitation[26]. DHsystemsinruralareas,whereenergydemandpatternsarelesshomogenousthaninurbanareas(withhigherbuildingdensitiesandnaturalgasnetworks),requirespecificlocalevaluation.Themethodologyallowstheevaluationofthesenon-repeatable energydemandandresourcepatternsbyusingspecificcorrectionfactors.Itfullycoversthe2012/27/EUDirectiveforevaluationofpotentialDHsystems.Themethodologycomprisesthefollowingstages: Fig.1Top-Down/Bottom-uplevelstudy. alt-text:Fig.1 Step1 Regionalcharacterisation The first step is the definition of the area under analysis, at a global level. Different features can be found as function of the area characteristics regarding the heating energy demand and fuel availability. A rough classification can be in terms of urban/industrial/ruralareasalthoughanyotherwithspecificcharacteristicscandefined. Step2 ThermalSystemassessment.Preliminaryevaluation Fortheselectedarea,energydemandisevaluatedasthesumofSanitaryHotWater(SHW)andheatingdemand.SHWcanbeestimatedbasedonconsumptionratesaccordingtolocalregulation,whileheatingdemandcanbecalculatedevaluatingenergy lossestotheambientthroughbuildingenvelopes,andtheeffectsofexternal(solarradiation)andinternal(occupationanddomesticelectricalequipment)gains[14]. Themethodologyproposesmakingapriorevaluation,basedonaglobalmacro-scaleevaluationbymeansofspecificlocalsurveys.Moreover,preliminarydatacanalsobeextractedfromgeographicinformationsystem(GIS)tools,suchasthosedeveloped withintheSTRATEGOproject[27].TheSECH(DevelopmentofdetailedStatisticsonEnergyConsumptioninHouseholds)[28]projecthasdevelopedstatisticsforenergyintheresidentialsectorbyapplyingBottom-Upmethodologies,measurementsandmodels. OnceestimatedtheaggregatedenergydemandofthebuildingssuppliedbytheDHandthenetworksize,thelinearheatdensity(LHD)canbecalculatedassumingacertainaveragenetworklength.Thenetworkheatlossescanbeestimatedandlinkedtothe LinearHeatDensityusingcorrelations[29],asexpressedinEq.(1): Heatdistributionlossescanbeintherangeof5–25%dependingonthelocation,networkoperationtemperature,networksize,isolationandmaintenance[30,31].ForanefficientDHsystem,annualenergylossesmustbebelow10%[14]. Step3 BioDHviabilityfactors ThisstageimpliestheevaluationofthefactorsthatdirectlyinfluencetoBioDHviability: •Biomassresources:Costandavailabilitymustbeanalysed.ThisevaluationcanbebasedonavailabledatafromGIStoolsorstatisticaldatabases. •Environmentalfactors:identificationofavailablespacesforpipingandthermalstationplant.Definitionoflocationscharacteristicsandrequirementsforthermalstationplant,transferenergystationsandadjacentareas.Definitionofcontaminantsandparticledispersionrequirements andsafetydistances. •Socioeconomicfactors.Theseshouldincludeanalysesof: -Energypoverty,whichisarelevantindicatorforthedevelopmentofpoliciesthatimprovethewell-beingofcitizens.Energypovertydistortsuserdemandprofilesandheatingdemandestimations.Usually,inlocationswithgreaterenergypovertypercentage,therealdemandwillbelowerthanthatestimatedbytraditionalmethods,penalizingthe viabilityofBioDHsystems. -Dwellingsoccupancy.Manyruralareasarecharacterisedbypartiallydepopulatedmunicipalitiesandfrequentlyhavearelevantpercentageofsecondresidencehomes.Intheareaunderstudy,theproportionofunoccupieddwellings,forweekendsorholidaysuses,tothoseinpermanentusemustbeidentified. Step4 Municipalityassessment AfteridentificationofpotentialBioDHlocations,thisstagedefinesthespecificBioDHdetails.Heatingdemand,upto90%oftheenergydemandofthedistrictheating,isthekeyfactorfortheeconomicevaluationofthesystems.Thepredictionoftheannual revenuesofBioDHdependsdirectlyonthecorrectevaluationofthedemand.Thetheoreticaldemandisdefinedbyconsideringtheinfluenceofexternal(solarradiation)andinternal(occupationanddomesticelectricalequipment)gains[14]. Thepresentmethodology,whichisspecificforBioDHsystemsinruralareas,andwithcorrectionindicestakingintoaccountthefactorsdefinedinStep3,proposesanenergydemandevaluationfollowingthestructureshowninFig.2. (1) Fig.2Top-Down/Bottom-upstepsmethodology. alt-text:Fig.2 Fig.3Energydemandevaluationscheme. Themethodologyforenergydemandevaluationinruralareasiscorrectedforseveralfactors: i) Dwellingsoccupancy:theoreticaldemandiscorrectedbyanintermittencefactorthatmustbeadjustedandcalibratedfortheregionunderanalysis.Inthisworkthisfactorissetto0.78orpermanentresidencesof[14],andto0.4fordwellingswithseasonalandparttimeuse(i.e: weekendsandholidaysperiods). ii) Energypoverty:itonlyaffectstopermanentdwellings.Ausualdefinitionofenergypovertythresholdisgivenbythepercentageoftotalhouseholdincomesusedformaintainingenoughcomfortlevelsinthedwelling(forheating,21 °Cinthemainroomand18 °Cintheotherrooms). Inthiswork,forthedefinitionofenergypoverty,athresholdof10%ofhouseholdincomesdedicatedtopaytheenergybillhasbeenused.Morerecentenergypovertymetrics[32,33]canbeusedifenoughdisaggregateddataforthelocationunderanalysisareavailable.Detailed informationforenergypovertycanbedeterminedbymeansoflocalsurveys. Foramoredirectapproach,theaveragepercapitaincomeforthedifferentstudypopulationscanbeobtainedfromsocio-economicstatisticsdatabases.The10%ofthepreviousvalueiscomparedwiththecostofenergyforthedifferenttheoreticaldemands, influencedbythelocationandthetotalheatedareaoftheresidence.Thereferencebaselinecostiscalculatedfromtheheatingsystemfuelpriceandtheaverageseasonalperformanceoftheconventionalsystem. Theproposedcorrectionfactorontheenergydemandintermsofenergypoverty,onlyapplicabletopermanentresidences,canbeapproachedbyanexponentialexpressionsuchastheoneshowninFig.4,wheretheshapeisadjustedtothecharacteristicsof eachlocationunderthepreviousconsiderations. iii) Ageofthebuildings:foramoreaccurateevaluationofheatingdemandatmunicipalitylevel,thetheoreticaldemandmustbecorrectedasfunctionofthetimesincetheirconstructionorlastrehabilitation.Inthisworktheuseofcorrectionfactor isproposed.Itevaluatesthe numberofbuildingsintermsoftheirconstructionperiodorlastrefurbishment.Thesedatacanbeestimatedfrommunicipalitydatabases,withreasonable,ifnotexact,estimationsoftheaverageageofbuildingsordistricts.Asageneralrule,morerecentbuildingshaveanimproved andsmallerdemands,astheyweredevelopedundermodernefficiencyregulations.Fig.5showsthemeanvaluesofheatingdemandperunitareacomparedtobuildingageforSpain.Itcanbeseenhowforthiscasethereisaclearincreaseofdemandperunitareawiththeage ofthebuilding.Thisevolutionmustbeevaluatedforeachregion,adjustingthetimescaleasappropriate,althoughinMediterraneancountriessimilarprofilesareexpected. alt-text:Fig.3 kage kage Fig.4Energypovertyandenergydemandcorrelation. isthetheoreticaldemandperinhabitant, isenergypovertyinthemunicipality, isthedemandsensitivitytoenergypovertycoefficient, ismunicipalitypopulation(%). alt-text:Fig.4   EPkEPH AnimportantpointfortheanalysisofBioDHviability,istotakeintoaccountfuturedemandevolutionandtheforecasteddecreaseofdegreedaysinthelifetimeofthesystem.InRef.[34],thedecreaseofthedegreedayswasestimated,evaluatingaperiodfrom 1958to2005,projectingthreefuturescenariosofglobalwarming.Undertheintermediatescenario,adecreaseofmeandegreedaysof1.8%perdecadewasestimated.Inaddition,improvementintheenergyefficiencyofbuildingsshouldbeexpectedduetoregulations onnewbuildings,buildingrehabilitationandtheintegrationofothertechnologies.Thismeanvaluecanbeincludedasacorrectionfactorfortheevaluation,althoughmorepreciseevaluationscanbeconsidered. ThelengthofthenetworkisakeydifferentiatorbetweenBioDHsystems.Alongerlengthimpliesagreaterinvestmentandanexpectedlowerprofitability.Itisdirectlyrelatedtoheatlossesforagiveninsulation,asitdirectlyaffectsoperatingcosts.Thefactors influencingthelengthofthenetworkforagivenmunicipalityaretheurbanarea(SDH,seeFig.6)andtherelationshipbetweentheareaofbuildingsandthatofroadsandpavements,whichdeterminesthebuildingdensity .Thelasttwoparameterscanbe characterisedbythedepthofthedistrictLcandthewidthofthestreetsandpavements,Lr.TheurbanhomogeneityoftheareaunderstudyshouldbeanalysedtoobtaintheratiobetweenthelengthofthenetworkandSDH.Inthisway,thelengthofthenetworkforall BioDHscouldbeevaluatedbymeansofEq.(2): Foreachbuilding,thespecificnetworklength isgivenbyRef.[35]: Theratiobetweenbothparameterscanbeadjustedfromextrapolationoftheexistingdataoralreadydesignednetworks,foramoreaccuratespecificnetworklengthestimation.Inthisway,itwouldbepossibletoevaluatethelengthofthenetworkforallBioDHin thearea. Biomassavailabilityandpricemustbeevaluated.Whenavailable,asisthecaseindifferentcountriesofEurope,suchasSpain,thesedatacanbeevaluatedusingGIStoolsthatprovidebiomasscharacteristics(LHV,humidity)andextractioncosts(seeFig.7).If suchinformationisnotavailable,itmustbecompiledfromdifferentsources. Fig.5MeanheatingdemandasafunctionofbuildingageinSpain. alt-text:Fig.5 (ρbuilding) (2) Fig.6Networklengthcharacterisation. alt-text:Fig.6 Lspec (3) Biomassavailabilityisestimatedintermsofbiomasstype, ,andexploitationcost, .Ifbiomassmustbeimportedfromneighbouringareas,withtheassociatedchallengesforbiomassexploitationandmanagement[36],biomasscomposition, ,and supplycost, [€/ton]mustbeincluded.ThemeanbiomasscostpertonneisgivenbyEq.(6): Step5 Costandbenefitevaluation Cost-Benefitanalysisisusedforevaluatingviabilityofeachspecificsystem[14,26].Itinvolvestheanalysisof: i) CapitalExpenditures(CAPEX).Itincludesallinvestmentstostartupthesystem:biomassthermalpowerstation ,distributionnetwork andenergytransferstations . TheexpectedthermalplantinvestmentinthelowerpowerrangeofBioDHsystemsisfrom855€/kWto1453€/kW,definedintermsoftheglobalpower[37,38].Thesepricesinclude:biomassboiler;alternativefuelback-upboiler;piping,pumpsandcontrol system;fuelstorage;electrostaticprecipitator;engineering;construction;and,contingencies.Howeverforinstallationsintheupperpowerrange,8 MW–50 MW,lowerunitinvestmentscostsareexpectedduetoeconomiesofscale,withvaluesintherangefrom200€/kW to250€/kW. Distributionnetworkcostisbeevaluatedintermsoflengthandspecificdiameter.Thespecificpipediameterisgiven[25]: wheredaisthepipediameter(m),and thenetworkpipelength(m),togetherwithD,formsD/LPthelinearheatdensity(GJ/m).Accordingto[25],networkinvestmentcanbeevaluatedasfollows: whereC1istheconstructioncostconstant[€/m]andC2istheconstructioncostcoefficient.TheestimatedvaluesgiveninRef.[35]forruralareasareC1 = 251.30€/mandC2 = 2026.03€/m. However,althoughinsystemswithsimilarequivalentoperatinghours,thediameterofthepipecanberelatedtothelinearheatingdensity[25],thediameterunderthesameoperatingconditions,temperature,velocityandpressuredrop,thevolumetricflowrateis proportionaltothepowertransmittedbythenetworkandisthereforeproportionaltothesquareofthediameter.Thepipecostsareproportionaltothepipediameter.Theinvestmentinthenetworkis: Theuseofplasticpipesasasolutionforheatingdistributionnetworkshasconsiderablyreducedpipecosts,reducingthecostoffittingsandcivilworks,bysignificantlyreducinginstallationtimes.Fromtheresultsofthecasestudiesdevelopedinthereal Fig.7GISanalysesofbiomassresources. alt-text:Fig.7 Qmi Pmi Qexti Pexti (4) (CAPEXTP) (CAPEXN) (CAPEXETS) (5) (6) LP (7) (8) applicationinthiswork,updatedvaluesforthispipetechnologyareestimatedasC1 = 120€/mandC3 = 750€/m W0.5. ii) ReferenceBaselinedefinition.Thebaseline forevaluatingBioDHimpact,isdefinedintermsofthetechnologiesusedforheatingandSHW.Itisdefinedintermsoffinalenergycost,functionofsystemefficiencyandfuelcost,anditincludesdepreciationandmaintenancecosts ofindividualsystems(Eq.(7))[14,26].AssustainabledesigncriteriathesellingpriceofenergyforwiththeBioDHshouldbebelowthecostoftechnologiestobedisplaced ,andabovethetotalenergyproductioncost. where isthenetworkfixedcost(€), and arethecentralandnetworkamortisationcostsrespectively, isthenetworkenergycost, isthefuelcostand isthetotalenergysold(kWh). iii) Incomes.BioDHincomes aregivenby: where istheenergydemanded(kWh)and istheendusersellingprice. Thispriceshouldbelowerenoughthanreferencebaselinepricetogiveaclearvaluetotheenduser.Inmanysystemsitischosentointroduceafixedcosttotheuser,whichwouldimplyfixedincomes.Inthisanalysis,thisoptionhasnotbeenconsidered. iv) OperationalExpenditures(OPEX).Mainoperationalexpendituresarebiomassfuelandpumpingconsumption.Theyarelinearlydependentonheatingdemand.Besides,fixedoperationcostsmustbeincluded.OPEXexpressionisgivenby: where istheproductofbiomassmeanprice, ,andenergyconsumedbythesystem. ,pumpingcost,dependsontheheatdemandandtoalesserextentonthetopologyofthenetwork.Aroughestimationoffixedcosts, , for this applicationis5.5%oftheinvestment[39,40]. v) Viabilityanalysisandreturnontheinvestment.ThelifetimeperioddependsonthermalgenerationtechnologiesfortheBioDHthermalstationandDHnetworktechnologiesandmaterials.Infrastructuredesignswithlifetimeperiodsabove30yearsmustbeconsidered[26].Investment returnrate(IRR)istheparameterchosenforevaluationandcomparisonoftheprojects: Steps6and7.EvaluationofthepotentialofaBioDHsystemandenvironmentalassessment OnceaviabilitythresholdisdefinedforBioDHsystems,whichineachcasemaybedifferent,alowerlimitfortheprofitabilityofabiomassheatingnetworkissettoensureitseconomicandtechnicalviability.Itdeterminesthepotentialofbiomassheating networksforagivenareaorregion.Theprofitabilitythresholdisinfluencedbyrequirementsoftheprivateinvestmentinitiativeandregulations. AvoidedCO2emissionswiththerenewableforestrybiomassareevaluatedwiththeconversionfactoroffuel[26,41]: where istheindividualboilerefficiencyreplacedbytheBioDHsystem,and istheconversionfactorfordieselfuel. 3ApplicationofthemethodologytotheSpanishcontinentalclimateregion 3.1ExistingBioDHsystems ThissectionpresentsthedetailedresultsobtainedfortheapplicationofthemethodologytofourDHsystemsoperatinginSpain:oneinthenorth(BioDHN),twointhecentralarea(BioDHC1andBioDHC2)andoneinthesouth(BioDHS).Thesecasesareusedfor calibratingthemethodology.Energydemandandinstalledpowerwereevaluatedthroughsurveysbythecompanyinchargeofthedistrictheatingsystemimplementation,incollaborationwiththeauthors.Thesurveycoversmorethan70%ofhomesintheareas.The (Lbase) Lbase (9)           Esold (In) (10) D PricekWh (11)         (12) (13)   GHGDiesel mostimportantindicesarethoseshowninTable1. Table1ResultsofthestudyofBioDHimplementationin4municipalities. alt-text:Table1 BioDHNBioDHC1 BioDHC2 BioDHS Inhabitants 1919 1998 3069 1502 Grossaverageincomepercapita[€] 14,504 22,878 14,709 13,708 Giniindex 0.42 0.44 0.45 0.46 EnergyPoverty[%] 62.83 38.27 56.24 39.28 Dwellings 1180 1775 1860 967 -Firstresidence 745 770 1105 530 -Secondaryresidence 305 775 550 294 -Unoccupieddwellings 130 210 205 144 Correctionindexaccordingageofbuildings 0.87 0.86 0.89 0.85 Municipalityurbanarea[m2] 410,620 583,321 861,126 229,614 Networklength(fromengineeringdesign)[m] 8632 11,230 15,560 5126 Networklength(fromEq.(2))[m] 8456 11,904 17,571 4792 RelativeerrorfromNetworklength[%] 1.97 8.58 16.53 4.53 Altitude[masl] 1200 1157 1068 1230 Minimumtemperature[ºC] −7.4 −5.4 −5.8 −4.9 DegreeDays[ºCHDD] 4133 3359 2765 3439 Thermalpower[MW] 8 12 16 8 CAPEXtotalBioDH[k€] 4206 6398 8928 3430 -CAPEXTh[k€] 1733 2615 3378 1667 -CAPEXN[k€] 1541 2376 3732 866 -CAPEXETS[k€] 932 1407 1818 897 CO2tonnesavoided 22,737 1,207,92 2,451,08 850,772 503,081 361,412 5,396,997 Correctedenergydemand[MWh/y] 51,177 2,718,790 5,516,890 1,914,920 1,132,340 813,469 12,147,590 Revenues[k€/y] 3480 184,877 375,149 130,215 76,999 55,316 826,036 Totaloperationcost(fuelandO&M)[k€/y] 1730 66,640 114,740 35,488 19,971 13,051 251,620 Linearheatdensity[MWh/m·y] 0.48–0.73 0.48–2.31 0.50–4.73 0.69–9.14 0.99–9.12 1.14–5.03 0.48–9.12 Equivalentworkinghours(h/y) 876-1433 875- 1926 1158–2210 1276–2204 1357–2619 1575–2403.4 875- 2619 Localbiomassprice[€/t] 71.77–80.52 67.86–80.52 32.42–75.85 32.42–75.85 27.84–67.86 27.84–42.35 27.84- 80.52 4Conclusionsandfinalremarks ThispaperpresentsamethodologyfortheanalysisofthepotentialforBioDHnetworksinruralareas.Theyarecharacterisedbyrelativelylowlinearheatdensitiesandproximitytobiomassresources,andahighdispersioninthedemandnetwork,comparedto homogeneousurbanareas. Themethodologyaddscorrectiontermstothewell-establishedlinearheatdensityestimationsusedforevaluatingdistrictheatingviabilityinurban/homogenousareas.Theyareincludedintheformofcorrectionfactorsthatevaluatethetypeofuseofdwellings, buildingage,energypovertyinthemunicipalityandnetworkcharacteristics.Correctionfactorsbasedonexistingnetworksareincludedforcalibratingthemethodologyinaspecificregiontoimproveaccuracyofthemethodology.Byusingexistingdata,themethodology wasappliedtoanalyseanumberofmunicipalitiesincontinentalSpain,where499municipalitiesweredetectedwiththepotentialforimplementingaBioDHsystem.Inthesemunicipalitiestheequivalentoperatinghoursvaryfrom875to2,619,andlinearheatdensity variesfrom0.48to9.12 MWh/m·y.Fromtheeconomicpointofview,IRRvariesintherangefrom−0.4%to14.7%,with154BioDHsystemshavinganIRRabove5%. Theenergypovertyintheregionanalysedinthisstudyvariesfrom25.18to78.09%,whichisconsiderablyhigherthantheSpanishaveragevalue.ThisisduetothelocationofBioDHsystemsunderanalysis,wherenaturalgasisnotavailableandfueltransport increasesendusercosts.Thewiderangeofbiomasspriceforthedifferentlocations,from27.84to80.52€/t,makesthisfactordeterminantfortheviabilityoftheBioDHsystem. TheimplementationofDHsystemscouldmitigateenergypovertyandpromotethecirculareconomy.Moreover,extensivelyapplyingtheproposedmethodologythroughoutallmunicipalitieswithinaregion,wouldallowthedevelopmentofenergypoliciesanda clearimpulseforthelocaleconomybytheconstructionofdistrictheatingsystemsandbiomassforestryexploitation.TheinvestmenttocarryouttheimplementationofalltheDHsystemsanalysedis4253 M€,whichwouldleadtoahugebusinessopportunityinrural areas.Itcouldhaveadditionalimpactsasbusinessattractortoreducethedemographicdeclineintheseareas.Fromtheenvironmentalpointofview,themassiveimplementationofBioDHsystemsintheregionunderanalysiswouldsave5.4 MtofCO2emissionsper year.TheCO2emissionssavings/investmentratioislowerthanthepresentedinurbanareas,wherehigherlinearheatdensitiesreducethedistributioncosts. Notation CapitalExpenditures InvestmentintheBioDHsystem(k€) Investmentofthethermalpowerplant(k€) Networkinvestment(k€) CAPEX CAPEXBioDH CAPEXTh CAPEXN CAPEXETS Energytransferstationinvestment(k€) CO2domesticboileremissions(t) BioDHfixedcost(€/year) Boileramortisationcost(€/year) Boilermaintenancecost(€/year) Centralamortisationcost(€/year) Biomassfuelcost(€/year) Networkamortisationcost(€/year) Networkenergycost(€/year) Networkfixedcost(€/year) Externalairaveragespecificheat(W·s/kgK) Heatingenergydemand(kWh) Districtheatingsystem Districtheatingandcoolingsystem Cp D DH DHC DEP Demandcorrectedforenergypoverty(MWh) SanitaryHotWaterdemand(MWh) TotalEnergyDemand(MWh) Averagetheoreticaldemand(MWh·H−1) Mainhousingdemand(MWh) Demandforsecondresidence(MWh) CorrectedDemand(MWh) Pipediameter(m) Energypoverty(%) Totalenergysold(kWh) EnergyTransferStation Conversionfactorfordieselfuel Inhabitants% Equivalentthermalhours DSHW Dt D1stResidence D2ndResidence D* da EP GHGDiesel H IRR Internalrateofreturn Indexofprofitabilityofbiomassheatnetworks Incomes Coefficientofageofbuilding Thermalconstantofthebuilding Coefficientofsensitivitytoenergypovertyofdemand Economicbaseline(€) Networkpipelength(m) Locationswithpopulationunder10,000inhabitantsandwithoutnaturalgasnetwork Netpresentvalue Operationalexpenditure Heatingpowerdemand(kW) Energyprice(€) BiomassPrice(€) IBIODH In kage Kbuilding kEP Lbase LP NGF10k NPV OPEX P PricekWh Pexti Priceofbiomassinothermunicipalities(€) Priceofbiomassinthemunicipality(€) Thermalpower(MW) Biomassobtainedfromothermunicipalities(t) Biomassavailableinthemunicipality(t) DistrictArea(m2) Energytaxes(€) Coldwatertemperature(ºC) Comforttemperature(ºC) Exteriorairtemperature(ºC) Globalcoefficientoftransmission(W/m2·K) Infiltrationairflow(m3/s) CO2emissionsavings(t) Individualboilerefficiency Pmi PTh Qexti Qmi SDH TaxesSpecial tcoldwater tc_indoor tout U Vainf ΔCO2 Externalairdensity(kg/m3) Hours References [1]U.S.Energyinformationadministration.Internationalenergyoutlook2016,2016,0484www.eia.gov/forecasts/ieo/pdf/0484(2016).pdf. 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QueriesandAnswers Query:Pleaseconfirmthattheprovidedemail(s)[email protected]is/arethecorrectaddressforofficialcommunication,elseprovideanalternatee-mailaddresstoreplacetheexistingone,becauseprivatee-mailaddressesshould notbeusedinarticlesastheaddressforcommunication. Answer:[email protected]iscorrect. Query:Pleaseconfirmthatgivennamesandsurnameshavebeenidentifiedcorrectlyandarepresentedinthedesiredorderandpleasecarefullyverifythespellingofallauthors’names. Answer:Thecorrectnamesandsurnamesare:V.M.Soltero Query:Yourarticleisregisteredasaregularitemandisbeingprocessedforinclusioninaregularissueofthejournal.IfthisisNOTcorrectandyourarticlebelongstoaSpecialIssue/Collectionpleasecontact [email protected]immediatelypriortoreturningyourcorrections. Answer:Yes Highlights •Top-down/bottom-upmethodologyforevaluatingbiomassdistrictheating. •Methodologyforevaluationdistrictheatingsystems. •Biomassdistrictheatingnetworksinruralareas. •CasestudyinthecontinentalregionofSpain. •Analysisoftheviabilityofbiomassheatingnetworksin499villagesplant.