Diesel Inventory Improvementsfor Regulatory DevelopmentPlanning and TechnicalSupport DivisionNovember 18, 20102OutlineEmissions Inventory DevelopmentTruck and Bus Rule InventoryOff-Road Rule InventoryConclusion3What is an emissions inventory?An estimate of current and future air pollutantemissionsCombines emissions measurements with dataon the population and operating characteristicsof different types of vehiclesMethods and data sources improve over timeIntroduction4How are future emissions forecasted?Current emissions are adjusted for growth andregulation requirements–Forecasted economic trends–New technology penetrationIntroduction5What types of data sources are used?Engine emission test dataAcademic researchAgency program informationMarket reports and industry surveysARB surveys and field studiesEconomic forecastsIntroduction6What’s different with in-use rules?New engine standards focus on manufacturersIn-use rules focus on fleets owned andoperated by individual businessesRequires understanding the nature of individualfleets and their operationsIntroduction7Truck and Bus InventoryComprehensive update in 2008Latest update is forrecession impactsOther refinements8Inventory UpdatesComprehensive 2008 update–Addressed variety of fleet categories–Incorporated new methods and data2010 update for recession–Adjusted economic assumptions–Other refinementsTruck and Bus Inventory9Inventory Update Public ProcessFirst workshop discussing updates April 20076 inventory workshops in 2007 and 20089 inventory workshops in 2009 and 2010Stakeholder participationInventory data and models available to publicTruck and Bus Inventory10Recession ImpactEmissions reduced by 25%Impact of recession based on fuel sales dataAgrees well with fuel estimatesTruck and Bus Inventory11Use of Economic ForecastsEvaluated latest near-term forecastsForecasts from UCLA, UOP, CA Department ofFinance, Beacon Economics, EnergyInformation Administration, CongressionalBudget Office, and othersFocus on 2014Truck and Bus Inventory12Economic Recovery ScenariosFaster scenario assumes eight year recoveryperiodSlower scenario assumes no return topreviously anticipated levelsApril report to Board used average scenarioAverage scenario consistent with UCLA andUOP transportation forecastsTruck and Bus Inventory13Scenarios Forecasting TruckActivityTruck and Bus Inventory14Scenarios Forecasting TruckActivityTruck and Bus Inventory15Scenarios Forecasting TruckActivityTruck and Bus Inventory16Truck and Bus InventoryScenarios Forecasting TruckActivity17Scenarios Forecasting TruckActivityTruck and Bus Inventory18Other RefinementsApplied 2008 statewide methods to developregional estimatesReduced out-of-state vehicle miles traveled inCaliforniaReduced emission rate estimates for oldervehiclesOverall these changes reduce emissions byabout 10 percentTruck and Bus Inventory19Results of PM2.5Inventory UpdateTruck and Bus Inventory0510152025302010 2014 2023

Statewide PM2.5 Tons per DayOriginalRecessionRecession + Refinements25%20Recent Public CommentsComments–Use a slow recovery scenario–Limitlifetimemileage to 600,000 miles–Reduceannualmileage assumptionsBased on review of the data staff concludescurrent inventory estimates are appropriateTruck and Bus Inventory21How waslifetimemileage updated?Refers to the cumulative miles traveled by atruck category over a lifetimeFleet average value used in calculationEmission rates increase with use2008 inventory used values greater than onemillionUpdated inventory average lifetime mileage is800,000Truck and Bus Inventory22ARB Response toLifetimeMileageCommentTwo approaches to estimating lifetime mileage–EPA approach suggests lifetime mileage of1,000,000 miles–Survey approach suggests 650,000 miles800,000 miles is an appropriate mid-pointlifetime mileage estimateTruck and Bus Inventory23EvaluatingLifetimeMileageEstimatesTruck and Bus Inventory24EvaluatingLifetimeMileageEstimatesTruck and Bus Inventory25EvaluatingLifetimeMileageEstimatesTruck and Bus Inventory26EvaluatingLifetimeMileageEstimatesTruck and Bus Inventory27How isannualmileage used?Inventory includes estimates of annual mileagebased on vehicle ageEmissions are the product of annual mileage andemission ratesReducing mileage attributed to older, dirtiervehicles would further reduce emissions2008 inventory included annual mileageadjustmentsTruck and Bus Inventory28ARB Response to Annual MileageCommentStaff compiled more than 11,000 records fromUS Census surveys, ARB surveys, and theBond, Moyer programs.Data are available to the publicResults support ARB estimatesTruck and Bus Inventory29Revised Off-Road Rule InventoryUpdated for 2007RulemakingSignificant updates toinventory methods usingnew dataEffect of recessionincorporated30Inventory UpdatesRule inventory completed in 2007–Started with EPA and ARB methods–Updated key inventory estimates with industrystudies, market reports–Supplemented with ARB surveys of industry2010 inventory improvements–New data reported through regulatory process–Comparison to fuel-based estimates–Impact of recessionIn-Use Off-Road31Inventory Update Public ProcessIn-Use Off-RoadPublic workgroup meetings starting in 20043 inventory workshops in 2006Executive Officer Hearing March 2010Meetings with stakeholders in 20108 inventory workshops in 2010All inventory data and models available to public32Sources of New InformationOff-Road rule reporting databaseDatabase of financed equipment sales inCaliforniaManufacturer provided engine downloadsARB 2008-2009 engine testingRevised human population forecastsUpdated employment data and forecastsIn-Use Off-Road33Key 2010 UpdatesNew methods and data–Equipment population–Hours of use–Load factorsRecession impactIn-Use Off-Road34Equipment Population UpdateNational survey data used in original estimatesNow California reporting data is usedCurrent equipment population is reduced from195,000 to 145,000In-Use Off-Road35Hours of Use UpdatePrior estimates based on industry marketreports and studiesNew California reporting data usedOn average activity is reduced 50% fromprevious estimatesNew data reflects both 2007 and 2009 activitylevelsIn-Use Off-Road36Load Factor UpdateNational study used in original inventoryRevised inventory uses data collectedfrom industry, ARB testing and academicstudiesNew load estimates are 30% lowerRevision consistent with recent studies inother categoriesIn-Use Off-Road37Recession Impact and ForecastOriginal rule inventory based on 2005 data andcontinued growth forecastsRecession reduced emissions by 50% frompeak levelsRevised emissions forecastIn-Use Off-Road38In-Use Off-RoadScenarios Forecasting OffRoad Activity39In-Use Off-RoadScenarios Forecasting OffRoad Activity40In-Use Off-RoadScenarios Forecasting OffRoad Activity41In-Use Off-RoadScenarios Forecasting OffRoad Activity42Results of PM2.5InventoryUpdateIn-Use Off-Road43Comparison to Fuel SalesFuel sales used to evaluate new estimatesOnly total off-road sales are reportedRevised inventory based on reported activityUpdated fuel use is generally consistent withother estimatesIn-Use Off-Road44Summary of Inventory UpdatesTrucks and Buses–Revised inventory reduced 35% in 2010 dueprimarily to recessionOff-Road–Revised inventory reduced 80% in 2010; half due torecession and half due to new informationBoth inventories consistent with fuel salesestimatesInventory models and documentation availableto the public45ConclusionTruck/Bus and off-road emissions are lowerthan anticipated in the SIPProvides a margin for economic relief in 2014–Equal to 62 tons/day in South Coast–Equal to 40 tons/day in San Joaquin ValleyMeeting federal air quality standards requiresthe cleanest technologies for all sources