First published in December 19991DWLRQDO 3ROOXWDQW ,QYHQWRU\Emission EstimationTechnique ManualforGas SupplyGas SupplyiEMISSION ESTIMATION TECHNIQUESFORGAS SUPPLYTABLE OF CONTENTS1.0 INTRODUCTION 11.1 Manual Structure 21.2 Manual Application 22.0 PROCESSES AND EMISSIONS 43.0 REPORTABLE EMISSION SOURCES 53.1 Reporting Thresholds 53.1.1 Category 1 53.1.2 Category 2 53.1.3 Category 3 73.2 Emissions to Air 73.3 Emissions to Water 93.4 Emissions to Land 94.0 GLOSSARY OF TECHNICAL TERMS AND ABBREVIATIONS 105.0 REFERENCES 11APPENDIX A - EMISSION ESTIMATION TECHNIQUES 12A.1 Direct Measurement 13A.1.1 Sampling Data 13A.1.2 Continuous Emission Monitoring System (CEMS) Data 16A.2 Using Mass Balance 19A.3 Engineering Calculations 20A.3.1 Fuel Analysis 20A.4 Emission Factors 21APPENDIX B - EMISSION ESTIMATION TECHNIQUES: ACCEPTABLERELIABILITY AND UNCERTAINTY 23B.1 Direct Measurement 23B.2 Mass Balance 23B.3 Engineering Calculations 24B.4 Emission Factors 24APPENDIX C - LIST OF VARIABLES AND SYMBOLS 25Gas SupplyiiGAS SUPPLYLIST OF FIGURES, TABLES AND EXAMPLESFigure 1 - Gas Supply System - Overview 4Table 1 - Approximate Fuel Usage Required to Trigger Category 2 Thresholds 52 - NPI-listed Category 2 Substances 63 - Stack Sample Test Results 144 - Example CEMS Output for a Hypothetical Furnace Firing Waste Fuel Oil 17Example 1 - Category 2 Threshold Calculations 62 - Hydrogen Sulfide Emission Calculations 83 - Using Stack Sampling Data 144 - Calculating Moisture Percentage 165 - Using CEMS Data 186 - Using Fuel Analysis Data 21Gas Supply11.0 IntroductionThe purpose of all Emission Estimation Technique (EET) Manuals in this series is to assistAustralianmanufacturing,industrialandservicefacilitiestoreportemissionsoflistedsubstancestotheNationalPollutantInventory(NPI).ThisManualdescribestheproceduresandrecommendedapproachesforestimatingemissionsfromthegassupplyindustry.EET MANUAL: Gas SupplyHANDBOOK: Gas SupplyANZSIC CODES: 3620PacificAir&EnvironmentPtyLtddraftedthisManualonbehalfofEnvironmentAustralia.IthasbeendevelopedthroughaprocessofnationalconsultationinvolvingStateandTerritoryenvironmentalauthoritiesandkeyindustrystakeholders.ParticularthanksareduetotheAustralianGasAssociationanditsmembersfortheirassistanceinthe development of this Manual.Gas Supply21.1Manual StructureThis Manual is structured as follows:Section 2.0 provides a brief overview of the gas supply industry.Section3.0summarisestheNPI-listedsubstances,whicharetriggered,orlikelytobetriggered, for the gas supply industry.Category 1, 2 and 3 substances are discussed inSections 3.1.1, 3.1.2 and 3.1.3 respectively.Sections 3.2, 3.3 and 3.4 detail the expectedemissionstoair,waterandlandrespectivelyfromtheindustry.Thesesectionsalsodescribethesourcesoftheseemissionsandwhereemissionestimationtechniquesforeach of these sources are to be found.Section4.0providesaglossaryoftechnicaltermsandabbreviationsusedinthisManual.Section 5.0 provides a list of references used in the development of this Manual.AppendixAprovidesanoverviewofthefourgeneraltypesofemissionestimationtechniques:samplingordirectmeasurement;massbalance;engineeringcalculationsand emission factors, as well as example calculations to illustrate their use.Referenceto relevant sections of this appendix is recommended in understanding the applicationof these techniques with particular respect to the gas supply industry.AppendixBprovidesadiscussionofthereliabilityanduncertaintyassociatedwitheach of the techniques presented in Appendix A.Appendix C provides a list of variables and symbols used throughout this Manual.1.2Manual ApplicationContext and use of this ManualThisNPIManualprovidesahowtoguidefortheapplicationofvariousmethodstoestimate emissions as required by the NPI.It is recognised that the data that is generatedin this process will have varying degrees of accuracy with respect to the actual emissionsfromgassupplyfacilities.Insomecasestherewillnecessarilybealargepotentialerrordue to inherent assumptions in the various emissions estimation techniques (EETs).EETs should be considered as points of referenceThe EETs and generic emission factors presented in this Manual should be seen as pointsofreferenceforguidancepurposesonly.Eachhasassociatederrorbandsthatarepotentiallyquitelarge.AppendixBdiscussesthegeneralreliabilityassociatedwiththevarious methods.The potential errors associated with the different EET options should beconsidered on a case-by-case basis as to their suitability for a particular facility.FacilitiesmayuseEETsthatarenotoutlinedinthisdocument.Theymust,however,seektheconsentoftheirrelevantenvironmentalauthoritytodeterminewhetheranyinhouseEETs are suitable for meeting their NPI reporting requirements.Gas Supply3Hierarchical approach recommended in applying EETsThisManualpresentsanumberofdifferentEETs,eachofwhichcouldbeappliedtotheestimationofNPIsubstances.Therangeofavailablemethodsshouldbeviewedasahierarchy of available techniques in terms of the error associated with the estimate.Eachsubstanceneedstobeconsideredintermsoftheleveloferrorthatisacceptableorappropriatewiththeuseofthevariousestimationtechniques.Also,theavailabilityofpre-existing data and the effort required to decrease the error associated with the estimatewill need to be considered.For example, if emissions of a substance are clearly very small,nomatterwhichEETisapplied,thentherewouldbelittlegainedbyapplyinganEETwhich required significant additional sampling.The steps in meeting the reporting requirements of the NPI can be summarised as follows:Category 1 and 1a Substances:Identify which reportable NPI substances are used (or handled by way of their incidentalpresenceinoreormaterials,orexceedsthebulkstoragecapacityfor1a),anddeterminewhethertheamountsusedorhandledareabovethethresholdvaluesandthereforetriggerreportingrequirements.SeeSection3.1.1ofthisManualforguidanceonwhichCategory 1 substances are likely to require reporting in the gas supply industry.Category 2a and 2b Substances:Determinetheamountandrateoffuel(orwaste)burnteachyear,theannualpowerconsumptionandthemaximumpotentialpowerconsumption,andassesswhetherthethreshold limits are exceeded.See Section 3.1.2ofthisManualforadiscussionofwhichCategory 2 substances are likely to be triggered in the gas supply industry.Category 3 Substances:Determinetheannualemissionstowaterandassesswhetherthethresholdlimitsareexceeded.ItisunlikelythatthisNPICategorywillrequirereportingforthegassupplyindustry.Those substances above the threshold valuesExaminetheavailablerangeofEETsanddetermineemissionestimatesusingthemostappropriate EET.Generally,itwillbeappropriatetoconsidervariousEETsasalternativeoptionswhosesuitability should be evaluated in terms of:the associated reliability or error bands; andthe cost/benefit of using a more reliable method.The accuracy of particular EETs is discussed in Appendix B.NPI emissions in the environmental contextItshouldbenotedthattheNPIreportingprocessgeneratesemissionestimatesonly.Itdoes not attempt to relate emissions to potential environmental impacts, bioavailability ofemissions or natural background levels.Gas Supply42.0 Processes and EmissionsThis Manual will cover the gas supply industry as defined under the ANZSIC Code 3620-Gas Supply.These operations include distribution of manufactured town gas, natural gasor liquefied petroleum gas (LPG).Discussion with the gas industry indicated that, at thetime of writing, town gas was no longer producedinAustraliaforgassupply.ItshouldalsobenotedthatthemajordifferencebetweengasandLPG,inthecontextofthisManual, is that LPG distribution through the mains system does not include high pressuretransmission (as is the case for natural gas).LPG is distributed from LPG vessels that arefilled periodically by road tankers.The treatment of natural gas is not covered under thisANZSIC code.Inverysimpleterms,transmissionrepresentsthehigh-pressuretransferofgas,usingcompressors,fromthepointofproductiontothecitygate.Distributioninvolvestheremainingtransportofthegasfromthecitygate(highpressure)tothecustomer(lowpressure).Figure1givesanoverviewofthegassupplysystem.Emissionsofconcernwith respect to the NPI are total VOCs and hydrogen sulfide released through losses in thepipingsystems.TheselossesaretobereportedasaggregatedemissionsundertheNPI.Somenaturalgastransmissionsystemsincludegascompressors.Inthesesystems,therewill also be NPI-listed releases as a result of gas combustion (to power the compressors).TransmissionCity GatePressure RegulatorPressure Regulator Pressure RegulatorCustomer Customer CustomerGas ProductionCustomer Customer CustomerTransmissionDistributionHigh PressureMedium PressureLow PressureFigure 1 - Gas Supply System - OverviewGas Supply53.0 Reportable Emission Sources3.1 Reporting Thresholds3.1.1 Category 1From discussions with industry and a review of the published data on gas composition itislikelythattheonlysubstancepresentinsufficientquantitiestotriggertheCategory1reporting threshold of 10 tonnes per annum is hydrogen sulfide (AGL, 1995).In addition,the Category 1a threshold of 25 tonnes per annum for volatile organic compounds (VOCs)will also be triggered.TheusageofeachofthesubstanceslistedasCategory1and1aundertheNPImustbeestimated to determine whether the 10 tonnes (or 25 tonnes for VOCs) reporting thresholdis exceeded.If the threshold is exceeded, emissions of these Category 1 and 1a substancesmustbereportedforalloperations/processes,eveniftheactualemissionsofthesubstances are very low or zero.3.1.2 Category 2TheCategory2thresholdisbasedonenergyconsumedoronfueluse.TheCategory2athreshold for fuel usage is triggered if:a facility burns 400 tonnes or more of fuel or waste per year; ora facility burns 1 tonne or more of fuel or waste per hour.The Category 2b threshold is triggered if:a facility burns 2000 tonnes or more of fuel or waste per year; ora facility uses 60 000 megawatt hours (MWh) or more of energy in a year; orafacilitysmaximumpotentialpowerconsumptionisratedat20megawatts(MW)ormore at any time during the year.Fromdiscussionswithindustry,thecombustionofgasinthegas-firedcompressorsthatformpartofthegastransmissionanddistributionsystemmayleadtoreportingonCategory 2 substances being triggered.ThefuelconsumptionrequiredtotriggertheCategory2thresholdsmaybefoundinTable 1.Table 1 - Approximate Fuel Usage Required to Trigger Category 2 ThresholdsFuel Type Category 2a Category 2bNatural Gasa5.30 * 105 m3 per reporting year, or at least1.32 * 103 m3 in any one hour in the reportingyear2.65 * 106 m3per reporting yearaAssuming ideal gas with a density of 0.755 kg/m3 at 15oC and 101.325 kPa. Natural gas (NSW) data from theNatural Gas Technical Data Handbook (AGL Gas Company (NSW) Limited, 1995)DiscussionswiththeindustryindicatethatthemaximumcompressorsizeusedintheAustraliangastransmissionsystemis10MWandthatcompressorsareonlyrunGas Supply6periodically.The following example illustrates the calculation procedure for determiningifaCategory2thresholdhasbeenexceeded.Itislikelythatsomeoperatorswilltriggerthe Category 2a threshold but it is unlikely that any will trigger the Category 2b threshold.Example 1 - Category 2 Threshold CalculationsWhatistheminimumpowerratingforcompressorsthatwilltriggerthehourlyCategory 2a threshold (of 1 tonne per hour or 1000 kg/hr)?Assume a turbine efficiency of 45%.Gross heating value of natural gas = 38.8 MJ/m (AGL, 1995)Density = 0.755 kg/m (AGL, 1995)Volume required to trigger = Threshold value / Density= 1000 kg/hr / 0.755kg/m= 1324 m/hrTurbine Power = Heating Value * Volume * Efficiency= 38.8 MJ/m * 1324 m/hr * 0.45= 23 126 MJ/hr= 6.42 MWTherefore,iftheturbinehasapowerratingof6.42MWorgreater,thentheCategory2areporting threshold will be exceeded (and, as a consequence, reporting will be required forCategory 2a substances).IfafacilitytriggerstheCategory2athreshold,allCategory2apollutantsneedtobereported. IfafacilitytriggerstheCategory2bthreshold,allCategory2bpollutantsneedto be reported, in addition to Category 2a substances.Category 2 substances are listed inTable 2.Table 2 - NPI-listed Category 2 SubstancesCategory 2a Substances Category 2b SubstancesCarbon MonoxideFluoride CompoundsHydrochloric AcidOxides of NitrogenParticulate Matter (PM10)Polycyclic Aromatic HydrocarbonsSulfur DioxideTotal Volatile Organic CompoundsArsenic & compoundsBeryllium & compoundsCadmium & compoundsChromium (III) compoundsChromium (VI) compoundsCopper and compoundsLead & compoundsMagnesium Oxide FumeManganese & compoundsMercury & compoundsNickel & compoundsNickel CarbonylNickel SubsulfidePolychlorinated Dioxins & FuransPLUS all Category 2a substancesGas Supply73.1.3Category 3Category3substancesinvolvethereleaseofnutrients(phosphorusandnitrogen)tosurface waters.This is unlikely to be an issue in the gas supply industry and no reportingof Category 3 substances is expected to be required.3.2 Emissions to AirTotal VOCs, hydrogen sulfide and Category 2 substances are the only likely substances torequire reporting by the gas supply industry under the NPI.VOCs and Hydrogen SulfideVOCsandhydrogensulfidearereleasedthroughlinelossesandthroughblowdownoperations.Fromdiscussionswiththegassupplyindustry,industryblowdownoperations generally no longer involve venting to atmosphere.However, if natural gas isventedtoatmosphere,thequantitiesofgasventedarerecordedforbillingpurposes.These estimated quantities may be used as the basis for NPI reporting.Emissions as a consequence of line losses can be estimated using the measured line losses(alsometeredforbillingpurposes)andtheconcentrationsinthegasstream.Example2illustrateshowthesedatamaybeappliedforthepurposesofemissionsestimation.Calculatingemissionsbasedonmeasuredlossescanbeappliedtobothtransmission(fornatural gas) distribution systems (for both natural gas and LPG).It shouldbe notedthatmostoftheLPGdistributionsystemsinAustraliaarerelativelynewand,asaconsequence, there should be negligible losses due to routine operations.It is likely that itisonlyaccidentsituations(eg.burstpipes)whichwouldleadtosignificantemissionsofNPI-listed substances.Unaccounted for gas (UAFG) consists of line losses and metering errors.To estimate linelosses,itcanbeconservativelyassumedthatallUAFGislineloss.Industryliteratureindicates that currently UAFG is 2.5% within the Australian gas industry (AGA, 1998b).Gas Supply8Example 2 - Hydrogen Sulfide Emission CalculationsAgasdistributioncompanysupplies70PJofnaturalgastoitscustomersperyear.ThecompanyhasanUAFGvalueof2%.Gassuppliedtothedistributorhasahydrogensulfideconcentrationof2.5mg/m3atSTP.EstimatethequantitiesoftotalVOCsandhydrogen sulfide emitted.Assume (conservatively) that all UAFG is losses.Convert energy value to an equivalent volume of gas:Gross heating value of natural gas = 38.8 MJ/m3 (AGL,1995)Equivalent volume of gas = Energy supplied / Heating value= 70 PJ/yr / 38.8 MJ/m3 * 109 MJ/PJ= 1.804 * 109 m3 at STP/yrVolume lost (emitted) = 2% of Equivalent volume= 0.02 * 1.804 * 109 m3 at STP/yr= 3.608 * 107 m3 at STP/yrEstimate VOC emissions:Total organic compounds (including methane) present in natural gas= 96.8% (AGL, 1995)If the methane content of natural gas is 90% (typical level)Volume of VOC = 6.8% of Volume lost= 2.454 * 106 m3 at STP/yrDensity of gas = 0.755kg/m3 (assumed to be the same as naturalgas. (AGL, 1995))Mass of VOC released = Volume * Density= 2.454 * 106 m3/yr * 0.755kg/m3= 1.853 * 106 kg/yr= 1 853 tonnes/yrEstimate H2S emissions:Concentration of H2S= 2.5mg/m3Mass of H2S emitted = Concentration * Volume lost= 2.5mg/m * 3.608 * 107 m3 at STP/yr= 90 200 000mg/yr= 90.2 kg/yrTherefore, the amounts to be reported would be 1853 tonnes/yr of VOC and 90.2 kg/yr ofhydrogen sulfide.Gas Supply9Category 2 substancesCategory 2 substances will be released from on-site combustion (eg. to generate power forthe compressors). Refer to the Emission Estimation Technique Manual for Combustion Enginesfor a discussion on how to estimate these emissions.3.3 Emissions to WaterIt is extremely unlikely that any reporting on emissions to water would be required for thegas supply industry.3.4 Emissions to LandIt is extremely unlikely that any reporting on emissions to land would be required for thegas supply industry.Under the NPI, the following are classed as transfers and are not required to be reported:discharges of substances to sewer or tailings dam;deposit of substances to landfill; and,removalofsubstancesfromafacilityfordestruction,treatment,recycling,reprocessing, recovery, or purification.ThedefinitionoftransferhasbeenclarifiedbytheNPIImplementationWorkingGroupas:All emissions of listed substances, except those which are directed to, and contained by,purpose built facilities, are to be reported to the NPI. This applies irrespective of whetherthesubstancesfateiswithinoroutsideareportingfacilityboundary.Withrespecttoreceipt of NPI-listed substances, such receiving facilities are to be operating in accordancewith any applicable State or Territory government requirements.Solid wastes, slurries, sediments and spilled materials may contain NPI-listed substances.It is expected that all of these substances will be sent to sewer, sent offsite for treatment orrecycling or sent to landfill.As a consequence, there will be no requirement to reportontheseemissions.Therefore,itislikelythattheonlyreportingrequirementsfortheindustry will relate to the following releases to land:spillsoraccidentalreleasestoland(ifspillsoccur,seetheEETManualforFugitiveEmissions for guidance on how to estimate these releases);releases to groundwater; andon-sitedisposalwheretheon-sitedisposaldoesnotmeetthedefinitionprovidedabove.Gas Supply104.0 Glossary of Technical Terms and AbbreviationsAGLANZSICCEMSCOCO2EETEFRLPGNEPMNOxNPIPM10SO2STPTransferTSPUAFGUSEPAVOCTheAustralianGasLightCompany.CommonlyreferredtoasAGL.Australian and New Zealand Standard Industrial ClassificationContinuous Emission Monitoring SystemCarbon MonoxideCarbon DioxideEmission Estimation TechniqueEmission Factor RatingLiquefied Petroleum GasNational Environment Protection MeasureOxides of NitrogenNational Pollutant InventoryParticulatematterwithanequivalentaerodynamicdiameterof10 micrometres or less (ie. 10m)Sulfur DioxideStandard Temperature and Pressure (0oC and 101.325 kPa)Transfersconsistofadepositofasubstanceintolandfill,ordischarge of a substance to a sewer or tailings dam, or removal of asubstancefromafacilityfordestruction,treatment,recycling,reprocessing,recoveryorpurification(NEPM,Clause3(3)).Emissions classed as transfers are not required to be reported underthe NPI.Total Suspended ParticulateUnaccounted for gas Consisting of line losses and metering errorsUnited States Environmental Protection AgencyVolatile Organic CompoundsGas Supply115.0 ReferencesAGA,1998a.ResearchPaperNo.8-GasTransmissionPipelines,TheAustralianGasAssociation, Canberra, ACT, 2601.AGA,1998b.ResearchPaperNo.9-GasDistributionandRetailing,TheAustralianGasAssociation, Canberra, ACT, 2601.AGLGasCompany(NSW)Limited,1995,NaturalGasTechnicalDataBook,IndustrialApplications Department - AGL Gas Company (NSW) Limited, Five Dock, Australia.ANZSIC:AustralianandNewZealandStandardIndustrialClassification,AustralianBureau of Statistics & NZ Dept of Statistics 1993, ABS Catalogue No 1292.0.USEPA.1997.EmissionFactorDocumentationforAP-42.UnitedStatesEnvironmentalProtection Agency, Office of Air Quality Planning and Standards. Research Triangle Park,NC, USA.http://www.epa.gov/ttn/chief/ap42.htmlThefollowingEETManualsareavailableattheNPIHomepage(http://www.environment.gov.au/net/npi.html),andfromyourlocalEnvironmentalProtection Authority:Emission Estimation Technique Manual for Combustion Engines; andEmission Estimation Technique Manual for Fugitive Emissions.Gas Supply12Appendix A - Emission Estimation TechniquesEstimates of emissions of NPI-listed substances to air, water and land should be reportedfor each substance that triggers a threshold.The reporting list and detailed information onthresholds are contained in the NPI Guide at the front of this Handbook.In general, there are four types of emission estimation techniques (EETs) that may be usedto estimate emissions from your facility.The four types described in the NPI Guide are:sampling or direct measurement;mass balance;fuel analysis or other engineering calculations; andemission factors.Select the EETs (or mix of EETs) that is most appropriate for your purposes.For example,youmightchoosetouseamassbalancetobestestimatefugitivelossesfrompumpsandvents,directmeasurementforstackandpipeemissions,andemissionfactorswhenestimating losses from storage tanks and stockpiles.If you estimate your emission by using any of these EETs, your data will be displayed ontheNPIdatabaseasbeingofacceptablereliability.Similarly,ifyourrelevantenvironmentalauthorityhasapprovedtheuseofEETsthatarenotoutlinedinthishandbook, your data will also be displayed as being of acceptable reliability.ThisManualseekstoprovidethemosteffectiveemissionestimationtechniquesfortheNPI substances relevant to this industry. However, the absence of an EET for a substancein this handbook does not necessarily imply that an emission should not be reported to theNPI.Theobligationtoreportonallrelevantemissionsremainsifreportingthresholdshave been exceeded.Youareabletouseemissionestimationtechniquesthatarenotoutlinedinthisdocument.Youmust,however,seektheconsentofyourrelevantenvironmentalauthority.Forexample,ifyourcompanyhasdevelopedsite-specificemissionfactors,you may use these if approved by your relevant environmental authority.You should note that the EETs presented or referenced in this Manual relate principally toaverageprocessemissions.Emissionsresultingfromnon-routineeventsarerarelydiscussed in the literature, and there is a general lack of EETs for such events.However, itisimportanttorecognisethatemissionsresultingfromsignificantoperatingexcursionsand/or accidental situations (eg. spills) will also need to be estimated.Emissions to land,airandwaterfromspillsmustbeestimatedandaddedtoprocessemissionswhencalculatingtotalemissionsforreportingpurposes.Theemissionresultingfromaspillisthe net emission, ie. the quantity of the NPI reportable substance spilled, less the quantityrecovered or consumed during clean up operations.Gas Supply13A list of the variables and symbols used in this Manual may be found in Appendix C.A.1 Direct MeasurementYou may wish to undertake direct measurement in order to report to the NPI, particularlyifyoualreadydosoinordertomeetotherregulatoryrequirements.However,theNPIdoesnotrequireyoutoundertakeadditionalsamplingandmeasurement.ForthesamplingdatatobeadequateandabletobeusedforNPIreportingpurposes,itwouldneedtobecollectedoveraperiodoftime,andtoberepresentativeofoperationsforthewhole year.A.1.1 Sampling DataStack sampling test reports often provide emissions data in terms of kg per hour or gramspercubicmetre(dry).AnnualemissionsforNPIreportingcanbecalculatedfromthisdata. Stack tests for NPI reporting should be performed under representative (ie. normal)operatingconditions.YoushouldbeawarethatsometestsundertakenforaStateorTerritorylicenseconditionmayrequirethetestbetakenundermaximumemissionsrating,whereemissionsarelikelytobehigherthanwhenoperatingundernormaloperating conditions.AnexampleoftestresultsissummarisedinTable3.Thetableshowstheresultsofthreedifferent sampling runs conducted during one test event. The source parameters measuredaspartofthetestrunincludegasvelocityandmoisturecontent,whichareusedtodetermineexhaustgasflowratesinm3/s.Thefilterweightgainisdeterminedgravimetricallyanddividedbythevolumeofgassampled,asshowninEquation1todetermine the PM concentration in grams per m3. Note that this example does not presentthe condensable PM emissions.Pollutantconcentrationisthenmultipliedbythevolumetricflowratetodeterminetheemission rate in kilograms per hour, as shown in Equation 2 and Example 3.Equation 1CPM= Cf / Vm, STPwhere:CPM= concentration of PM or gram loading, g/m3Cf= filter catch, gVm,STP= metered volume of sample at STP, m3Gas Supply14Equation 2EPM=CPM * Qd * 3.6 * [273 / (273 + T)]where:EPM= hourly emissions of PM, kg/hrCPM= concentration of PM or gram loading, g/m3Qd= actual stack gas volumetric flow rate, m3/s, dry3.6 = 3600 seconds per hour multiplied by 0.001 kilograms per gramT = temperature of the gas sample, CTable 3 - Stack Sample Test ResultsParameter Symbol Test 1 Test 2 Test 3Total sampling time (sec) 7200 7200 7200Moisture collected (g) gMOIST395.6 372.6 341.4Filter catch (g) Cf0.0851 0.0449 0.0625Average sampling rate (m3/s) 1.67 * 10-41.67 * 10-41.67 * 10-4Standard metered volume (m3) Vm, STP1.185 1.160 1.163Volumetric flow rate (m3/s), dry Qd8.48 8.43 8.45Concentration of particulate (g/m3) CPM0.0718 0.0387 0.0537Example 3 - Using Stack Sampling DataPM emissions calculated using Equation 1 and Equation 2 (above) and the stack samplingdata for Test 1 (presented in Table 3, and an exhaust gas temperature of 150C (423 K)).This is shown below:CPM= Cf / Vm, STP= 0.0851 / 1.185= 0.072 g/m3EPM= CPM * Qd * 3.6 * [273/(273 + T)]= 0.072 * 8.48 * 3.6 * (273/423 K)= 1.42 kg/hrTheinformationfromsomestacktestsmaybereportedingramsofparticulatepercubicmetre of exhaust gas (wet). Use Equation 3 below to calculate the dry particulate emissionsin kg/hr.Gas Supply15Equation 3EPM=Qa * CPM * 3.6 * (1 - moistR/100) * [273/(273 + T)]where:EPM= hourly emissions of PM in kilograms per hour, kg/hrQa= actual (ie. wet) cubic metres of exhaust gas per second, m3/sCPM= concentration of PM or gram loading, g/m33.6 = 3600 seconds per hour multiplied by 0.001 kilograms per grammoistR= moisture content, %273 = 273 K (0C)T = stack gas temperature, CTotalsuspendedparticulates(TSP)arealsoreferredtoastotalparticulatematter(totalPM).TodeterminePM10fromtotalPMemissions,asizeanalysismayneedtobeundertaken. The weight PM10 fraction can then be multiplied by the total PM emission rateto produce PM10 emissions. Alternatively, it can be assumed that 100% of PM emissions arePM10;ie.assumethatallparticulatematteremittedtoairhasanequivalentaerodynamicdiameterof10micrometresorlessie.10m.Inmostsituations,thisislikelytobeaconservativeassumption,butitmaybeasuitabletechniquetoobtainareasonablecharacterisation of emissions for the purposes of NPI reporting.To calculate moisture content use Equation 4.Equation 4Moisture percentage= 100 * weight of water vapour per specificvolume of stack gas/ total weight of thestack gas in that volume.( )( )STPSTP mmoistSTP mmoistRVgVgmoist+=,,* 1000* 1000* 100where:moistR= moisture content, %gmoist= moisture collected, gVm,STP= metered volume of sample at STP, m3STP= dry density of stack gas sample, kg/m3 at STP{if the density is not known a default value of 1.62 kg/m3may be used. This assumes a dry gas composition of50% air, 50% CO2}Gas Supply16Example 4 - Calculating Moisture PercentageA1.2m3 sample(atSTP)ofgascontains410gofwater.Tocalculatethemoisturepercentage use Equation 4.( )( )STPSTP mmoistSTP mmoistRVgVgmoist+=,,* 1000* 1000* 100gMOIST/1000 * Vm,STP= 410 / (1000 * 1.2)= 0.342moistR= 100 * 0.342 / (0.342 + 1.62)= 17.4%A.1.2 Continuous Emission Monitoring System (CEMS) DataAcontinuousemissionmonitoringsystem(CEMS)providesacontinuousrecordofemissionsovertime,usuallybyreportingpollutantconcentration.Oncethepollutantconcentrationisknown,emissionratesareobtainedbymultiplyingthepollutantconcentration by the volumetric gas or liquid flow rate of that pollutant.Although CEMS can report real-time hourly emissions automatically, it may be necessarytoestimateannualemissionsfromhourlyconcentrationdatamanually.ThisSectiondescribeshowtocalculateemissionsfortheNPIfromCEMSconcentrationdata.Theselected CEMS data should be representative of operating conditions. When possible, datacollected over longer periods should be used.Itisimportanttonotethat,priortousingCEMStoestimateemissions,youshoulddevelop a protocol for collecting and averaging the data in order that the estimate satisfiesthe local environmental authoritys requirement for NPI emission estimations.TomonitorSO2,NOx,VOC,andCOemissionsusingaCEMS,youuseapollutantconcentration monitor that measures the concentration in parts per million by volume dryair(ppmvd=volumeofpollutantgas/106volumesofdryair).Flowratesshouldbemeasured using a volumetric flow rate monitor.Flow rates estimated based on heat inputusing fuel factors may be inaccurate because these systems typically run with high excessair to remove the moisture outofthekiln.Emissionrates(kg/hr)arethencalculatedbymultiplying the stack gas concentrations by the stack gas flow rates.Table 4 presentsexampleCEMSdataoutputforthreeperiodsforahypotheticalfurnace.Theoutputincludespollutantconcentrationsinpartspermilliondrybasis(ppmvd),diluent(O2orCO2)concentrationsinpercentbyvolumedrybasis(%v,d)andgasflowrates; and may include emission rates in kilograms per hour (kg/hr). This data representsasnapshotofahypotheticalboileroperation.Whileitispossibletodeterminetotalemissions of an individual pollutant over a given time period from this data, assuming theCEMSoperatesproperlyallyearlong,anaccurateemissionestimatecanbemadebyaddingthehourlyemissionestimatesiftheCEMSdataisrepresentativeoftypicaloperating conditions.Gas Supply17Table 4 - Example CEMS Output for a Hypothetical Furnace Firing Waste Fuel OilTime O2contentConcentration GasFlowRate(Q)ProductionRate ofProduct(A)% byvolumeSO2(ppmvd)NOx(ppmvd)CO(ppmvd)VOC(ppmvd) m3/s tonnes/hour1 10.3 150.9 142.9 42.9 554.2 8.52 2902 10.1 144.0 145.7 41.8 582.9 8.48 2933 11.8 123.0 112.7 128.4 515.1 8.85 270Hourly emissions can be based on concentration measurements as shown in Equation 5.Equation 5Ei =(C * MW * Q * 3600) / [22.4 * ((T + 273)/273) * 106]where:Ei= emissions of pollutant i, kg/hrC = pollutant concentration, ppmv,dMW = molecular weight of the pollutant, kg/kg-moleQ = actual stack gas volumetric flow rate, m3/s3600 = conversion factor, s/hr22.4 = volume occupied by one mole of gas at standardtemperature and pressure (0C and 101.3 kPa), m3/kg-moleT = temperature of gas sample, CActualannualemissionscanbecalculatedbymultiplyingtheemissionrateinkg/hrbythenumberofactualoperatinghoursperyear(OpHrs)asshowninEquation6foreachtypical time period and summing the results.Equation 6Ekpy,i = (Ei *OpHrs)where:Ekpy,i= annual emissions of pollutant i, kg/yrEi= emissions of pollutant i, kg/hr (from Equation 5)OpHrs = operating hours, hr/yrEmissionsinkilogramsofpollutantpertonneofproductproducedcanbecalculatedbydividingtheemissionrateinkg/hrbytheactivityrate(productionrate(tonnes/hr)during the same period.This is shown in Equation 7 below.It should be noted that the emission factor calculated below assumes that the selected timeperiod(ie.hourly)isrepresentativeofannualoperatingconditionsandlongertimeperiods should be used for NPI reporting where they are available.Use of the calculationis shown in Example 5.Gas Supply18Equation 7Ekpt,i = Ei / Awhere:Ekpt,i= emissions of pollutant i per tonne of product produced, kg/tEi= hourly emissions of pollutant i, kg/hrA = production, t/hrExample 5 illustrates the application of Equation 5, Equation 6 and Equation 7.Example 5 - Using CEMS DataThis example shows how SO2 emissions can be calculated using Equation 5 based on theCEMS data for Time Period 1 shown in Table 4, and an exhaust gas temperature of 150C(423 K).ESO2,1= (C * MW * Q * 3600)/[(22.4 * (T + 273/273) * 106]= (150.9 * 64 * 8.52 * 3600)/[22.4 * (423/273) * 106]= 296 217 907/34 707 692= 8.53 kg/hrFor Time Period 2, also at 150CESO2,2= 8.11 kg/hrFor Time Period 3, also at 150CESO2,3= 7.23 kg/hrSay representative operating conditions for the year are:Period 1 = 1500 hrPeriod 2 = 2000 hrPeriod 3 = 1800 hrTotal emissions for the year are calculated by adding the results of the three Time Periodsusing Equation 6:Ekpy,SO2= ESO2,1 * OpHrs + ESO2,2 * OpHrs + ESO2,3 * OpHrs= (8.53 * 1500) + (8.11 * 2000) + (7.23 * 1800) kg= 42 021 kg/yrEmissions, in terms of kg/tonne of product produced when operating in the same mode astime period 1, can be calculated using Equation 7Ekpt,SO2= ESO2 / A=8.53 / 290= 2.94 * 10-2 kg SO2 emitted per tonne of product producedWhen the furnace is operating as in time periods 2 or 3, similar calculations can beundertaken for emissions per tonne.Gas Supply19A.2 Using Mass BalanceAmassbalanceidentifiesthequantityofsubstancegoinginandoutofanentirefacility,process,orpieceofequipment.Emissionscanbecalculatedasthedifferencebetweeninputandoutputofeachlistedsubstance.Accumulationordepletionofthesubstancewithin the equipment should be accounted for in your calculation.MassbalancecalculationsforestimatingemissionstoairofNPI-listedsubstancescanberepresented conceptually by Equation 8.Equation 8Ekpy,i= Amount ini - Amount outiwhere:Ekpy,i= emissions of pollutant i, kg/yrAmount ini= amount of pollutant i entering the process, kg/yrAmount outi= amount of pollutant i leaving the process as a wastestream, article or product, kg/yrThetermAmountoutimayactuallyinvolveseveraldifferentfatesforanindividualpollutant.Thiscouldincludetheamountrecoveredorrecycled,theamountleavingtheprocessinthemanufacturedproduct,theamountleavingtheprocessinwastewater,theamountemittedtotheatmosphere,ortheamountofmaterialtransferredoff-siteashazardouswasteortolandfill.Athoroughknowledgeofthedifferentfatesforthepollutantofinterestisnecessaryforanaccurateemissionestimatetobemadeusingthemass balance approach.The amount of a particular substance entering or leaving a facility is often mixed within asolutionasaformulationcomponentorasatraceelementwithintherawmaterial.Todeterminethetotalweightofthesubstanceenteringorleavingtheprocess,theconcentrationofthesubstancewithinthematerialisrequired.Usingthisconcentrationdata, Equation 9 can be applied as a practical extension of Equation 8.Equation 9Ekpy,i= [(Qin * Cin) - (Qpr * Cpr) - (Qrec * Crec) - (Qwaste * Cwaste)] / 106where:Ekpy,i= emissions of pollutant i, kg/yrQin, Qpr, Qrec, Qwaste= quantity of raw material, product, recycled material or wasterespectively, that is processed (generally expressed in kg forsolids, L for liquids)Cin, Cpr, Crec, Cwaste= concentration of substance i in the raw material, product,recycled material or waste respectively, that is processed annually(usually mg/kg for solids, mg/L for liquids)106= conversion from milligrams to kilograms.Gas Supply20Wastewatertreatmentmayprecipitatethereportablechemicalinasludge.Facilitiesareoften required to obtain data on the concentration of metals or other substances in sludgesas part of their licensing requirement and this data can be used to calculate the emissionsaskilogramsofsludgemultipliedbytheconcentrationsofthesubstanceinthesludge.Althoughlistedsubstancesinsludgestransferredoff-sitedonotrequirereporting,determiningthislosscanassistwithdeterminingotherprocesslossesormayrequirereporting if the sludge is disposed of on-site.Formanychemicalsusedandemittedduringchemicalprocesses,somedegradationintreatment may occur so that the entire chemical is not transferred to the sludge.Facilitiescan estimate the amount of reportable compounds in the sludge by using measured data,orbysubtractingtheamountbiodegradedfromthetotalamountremovedintreatment.Theamountofremovalcanbedeterminedfromoperatingdata,andtheextentofbiodegradationmightbeobtainedfrompublishedstudies.Ifthebiodegradabilityofthechemicalcannotbemeasuredorisnotknown,reportingfacilitiesshouldassumethatallremoval is due to absorption to sludge.A.3 Engineering CalculationsAnengineeringcalculationisanestimationmethodbasedonphysical/chemicalproperties (eg. vapour pressure) of the substance and mathematical relationships (eg. idealgas law).A.3.1 Fuel AnalysisFuel analysis is an example of an engineering calculation andcanbeusedtopredictSO2,metals,andotheremissionsbasedonapplicationofconservationlaws,iffuelrateismeasured. The presence of certain elements in fuels may be used to predict their presenceinemissionstreams.Thisincludeselementssuchassulfurthatmaybeconvertedintoother compounds during the combustion process.The basic equation used in fuel analysis emission calculations is the following:Equation 10Ekpy,i = Qf * Ci/100 * (MWp/EWf) * OpHrswhere:Ekpy,i= annual emissions of pollutant i, kg/yrQf= fuel use, kg/hrOpHrs = operating hours, hr/yrMWp= molecular weight of pollutant emitted, kg/kg-moleEWf= elemental weight of pollutant in fuel, kg/kg-moleCi= concentration of pollutant i in fuel, weight percent, %Forinstance,SO2emissionsfromfueloilcombustioncanbecalculatedbasedontheconcentrationofsulfurinthefueloil.Thisapproachassumescompleteconversionofsulfur to SO2. Therefore, for every kilogram of sulfur (EW = 32) burned, two kilograms ofSO2 (MW = 64) are emitted.The application of this EET is shown in Example 6.Gas Supply21Example 6 - Using Fuel Analysis DataThis example shows how SO2 emissions can be calculated from fuel combustion based onfuelanalysisresults,andtheknownfuelflowoftheengine.Ekpy,SO2maybecalculatedusing Equation 10 and given the following:Fuel flow (Qf) = 20 900 kg/hrWeight percent sulfur in fuel = 1.17 %Operating hours = 1500 hr/yrEkpy,SO2= Qf * Ci/100 * (MWp / EWf) * OpHrs= (20 900) * (1.17/100) * (64 / 32) * 1500= 733 590 kg/yrA.4 Emission FactorsIntheabsenceofotherinformation,defaultemissionfactorscanbeusedtoprovideanestimateofemissions.Emissionfactorsaregenerallyderivedthroughthetestingofageneralsourcepopulation(eg.boilersusingaparticularfueltype).Thisinformationisusedtorelatethequantityofmaterialemittedtosomegeneralmeasureofthescaleofactivity(eg.forboilers,emissionfactorsaregenerallybasedonthequantityoffuelconsumed or the heat output of the boiler).Emissionfactorsrequireactivitydata,thatiscombinedwiththefactortogeneratetheemission estimates.The generic formula is:Equation 11= timemassRate Emission timeactivity of unit Data Activity*activity of unit massFactorEmission For example, iftheemissionfactorhasunitsofkgpollutant/m3offuelcombusted,thentheactivitydatarequiredwouldbeintermsofm3fuelburned/hr,therebygeneratinganemission estimate of kg pollutant/hr.Anemissionfactorisatoolusedtoestimateemissionstotheenvironment.InthisManual,itrelatesthequantityofsubstancesemittedfromasource,tosomecommonactivityassociatedwiththoseemissions.EmissionfactorsareobtainedfromUS,European, and Australian sources and are usually expressed as the weight of a substanceemitted, divided by the unit weight, volume, distance, or duration of the activity emittingthe substance (eg. kilograms of sulfur dioxide emitted per tonne of fuel burned).Gas Supply22Emission factors are used to estimate a facilitys emissions by the general equation:Equation 12Ekpy,i=[A * OpHrs] * EFi * [1 - (CEi/100)]where :Ekpy,i=emission rate of pollutant i, kg/yrA=activity rate, t/hrOpHrs =operating hours, hr/yrEFi=uncontrolled emission factor of pollutant i, kg/tCEi= overall control efficiency of pollutant i, %.Emissionfactorsdevelopedfrommeasurementsforaspecificprocessmaysometimesbeusedtoestimateemissionsatothersites.Shouldacompanyhaveseveralprocessesofsimilaroperationandsize,andemissionsaremeasuredfromoneprocesssource,anemission factor can be developed and applied to similar sources. It is necessary to have thesitespecificemissionfactorreviewedandapprovedbyStateorTerritoryenvironmentagencies prior to its use for NPI estimations.Gas Supply23Appendix B - Emission Estimation Techniques: Acceptable Reliability andUncertaintyThis section is intended to give a general overview of some of the inaccuracies associatedwitheachofthetechniques.AlthoughtheNationalPollutantInventorydoesnotfavourone emission estimation technique over another, this section does attempt to evaluate theavailable emission estimation techniques with regards to accuracy.Severaltechniquesareavailableforcalculatingemissionsfromgassupplyfacilities.Thetechnique chosen is dependent on available data, and available resources, and the degreeof accuracy sought by the facility in undertaking the estimate.B.1 Direct MeasurementUse of stack and/or workplace health and safety sampling data is likely to be a relativelyaccuratemethodofestimatingairemissionsfromgassupplyfacilities.However,collectionandanalysisofsamplesfromfacilitiescanbeveryexpensiveandespeciallycomplicated where a variety of NPI-listed substances are emitted, and where most of theseemissionsarefugitiveinnature.Samplingdatafromaspecificprocessmaynotberepresentative of the entire manufacturing operation, and may provide only one exampleof the facilitys emissions.To be representative, sampling data used for NPI reporting purposes needs to be collectedover a period of time, and to cover all aspects of production.In the case of CEMS, instrument calibration drift can be problematic and uncaptured datacan create long-term incomplete data sets. However, it may be misleading to assert that asnapshot(stacksampling)canbetterpredictlong-termemissioncharacteristics.Itistheresponsibilityofthefacilityoperatortoproperlycalibrateandmaintainmonitoringequipment and the corresponding emissions data.B.2 Mass BalanceCalculatingemissionsfromgassupplyfacilitiesusingmassbalanceappearstobeastraightforward approach to emission estimation.However, it is likely that few Australianfacilities consistently track material usage and waste generation with the overall accuracyneededforapplicationofthismethod.Inaccuraciesassociatedwithindividualmaterialtracking,orotheractivitiesinherentineachmaterialhandlingstage,canresultinlargedeviationsfortotalfacilityemissions.Becauseemissionsfromspecificmaterialsaretypicallybelow2percentofgrossconsumption,anerrorofonly5percentinanyonestep of the operation can significantly skew emission estimations.Gas Supply24B.3 Engineering CalculationsTheoretical and complex equations, or models, can be used for estimating emissions fromgassupplyprocesses.Useofemissionequationstoestimateemissionsfromgassupplyfacilities is a more complex and time-consuming process than the use of emission factors.Emission equations require more detailed inputs than the use of emission factors but theydo provide an emission estimate that is based on facility-specific conditions.B.4 Emission FactorsEveryemissionfactorhasanassociatedemissionfactorrating(EFR)code.ThisratingsystemiscommontoEETsforallindustriesandsectorsandtherefore,toallIndustryHandbooks.TheyarebasedonratingsystemsdevelopedbytheUnitedStatesEnvironmentalProtectionAgency(USEPA),andbytheEuropeanEnvironmentAgency(EEA).Consequently,theratingsmaynotbedirectlyrelevanttoAustralianindustry.Sourcesforallemissionfactorscitedcanbefoundinthereferencesectionofthisdocument.The emission factor ratings will not form part of the public NPI database.Whenusingemissionfactors,youshouldbeawareoftheassociatedEFRcodeandwhatthat rating implies.An A or B rating indicates a greater degree of certainty than a D or Erating.The less certainty, the more likely that a given emission factor for a specific sourceorCategoryisnotrepresentativeofthesourcetype.Theseratingsnotwithstanding,themaincriterionaffectingtheuncertaintyofanemissionfactorremainsthedegreeofsimilaritybetweentheequipment/processselectedinapplyingthefactor,andthetargetequipment/process from which the factor was derived.The EFR system is as follows:A - ExcellentB - Above AverageC - AverageD - Below AverageE - PoorU - UnratedGas Supply25Appendix C - List of Variables and SymbolsVariable Symbol UnitsConversion from kilograms to tonnes 103kg/tonneConversion from milligrams to kilograms 106mg/kgDensity of air akg/m3Density of material mkg/LDry density of stack gas sample STPkg/m3 at STPActivity rate A units/hr, eg. t/hrSurface area area m2Overall control efficiency CEi% reduction in emissions of pollutant iFilter Catch CfgramsConcentration of pollutant i Cikg/LConcentration of pollutant i in material Cikg/LConcentration of substance i in the rawmaterial, product, recycled material orwaste respectively, that is processedannuallyCin, Cpr, Crec,Cwaste(usually mg/kg for solids, mg/L forliquids)Concentration of PM10 CPM10grams/m3Uncontrolled emission factor for pollutant i EFikg of pollutant/tonneTotal emissions of pollutant i per hour Eikg/hrEmissions per tonne Ekpt,ikilograms of pollutant i per tonne offuel consumedAnnual emissions of pollutant i Ekpy,ikg/yrElemental weight of pollutant in fuel EWfkg/kg-moleMolecular Weight of pollutant i MWikg/kg-moleOperating hours OpHrs hr/yrPollutant concentration ppmvdvolume of pollutant gas/106 volume ofdry airSaturation vapour pressure of pollutant i Psat,ikilopascals (kPa)Total pressure PtkPaVapour pressure of pollutant i Pvap,ikPaVolumetric flow rate, Q m3/sVolumetric flow rate of stack gas Qaactual cubic metres per second (m3/s)Volumetric flow rate of stack gas Qddry cubic metres per second (m3/s)Fuel used Qft/hrMaterial entering the process Qin orAmount inikg/hrMaterial leaving the process Qout orAmount outikg/hrIdeal gas constant R kPa.m3 /(kgmol).KStandard Temperature & Pressure STP 0oC (273 K) and 1 atmosphere 101.3 kPaTemperature ToCelsius (oC) or Kelvin (K)Total suspended particulates orTotal particulate matter (total PM)TSP orPMmg/m3Metered volume at STP Vm,STPm3Total VOC emissions EVOCkg/LMoisture collected gmoistgramsMoisture content moistR%Percentage weight of pollutant i Wt%i%