Mobile Source Inventories Mobile Source Inventories for SIPsfor SIPs

Matt LauritaMatt Laurita

Air Quality Modeling and Transportation Air Quality Modeling and Transportation SectionSection

EPA Region 4EPA Region 4

What You NeedWhat You Need MOBILE6.2 modelMOBILE6.2 model ““Technical Guidance on the Use of MOBILE6 Technical Guidance on the Use of MOBILE6

for Emission Inventory Preparation”for Emission Inventory Preparation” Vehicle Miles Traveled (VMT) and SpeedsVehicle Miles Traveled (VMT) and Speeds

Base year and estimated future valuesBase year and estimated future values Local dataLocal data

Fleet age distribution, fleet mix, meteorological dataFleet age distribution, fleet mix, meteorological data Control programsControl programs

Inspection & Maintenance (I/M), anti-tampering, etc…Inspection & Maintenance (I/M), anti-tampering, etc…

For PMFor PM2.52.5: AP-42, Chapter 13: AP-42, Chapter 13

What You NeedWhat You Need NONROAD2004 ModelNONROAD2004 Model Emissions and Dispersion Modeling System (EDMS) Emissions and Dispersion Modeling System (EDMS)

ModelModel ““Procedures for Emission Inventory Preparation – Procedures for Emission Inventory Preparation –

Volume IV: Mobile Sources” (EPA420-92-009)Volume IV: Mobile Sources” (EPA420-92-009) Category 3 Marine Diesel Engines - Final Emission Category 3 Marine Diesel Engines - Final Emission

Standards Final Regulatory Support Document Standards Final Regulatory Support Document (EPA420-R-03-004)(EPA420-R-03-004)

Final Regulatory Impact Analysis: Control of Emissions Final Regulatory Impact Analysis: Control of Emissions from Marine Diesel Engines (EPA420-R-99-026)from Marine Diesel Engines (EPA420-R-99-026)

MOBILE6.2MOBILE6.2

EPA’s approved motor vehicle emissions EPA’s approved motor vehicle emissions modelmodel

MOBILE6.2 is used forMOBILE6.2 is used for SIP developmentSIP development Transportation conformityTransportation conformity Emission inventoriesEmission inventories Special studiesSpecial studies

MOBILE6.2MOBILE6.2

Computer model that predicts vehicle Computer model that predicts vehicle emissions on a grams per mile basisemissions on a grams per mile basis

Freely available (download)Freely available (download) DOS basedDOS based Contains default national data on fleet Contains default national data on fleet

mix, average speeds, age distributions, mix, average speeds, age distributions, etc…etc…

User can input detailed local dataUser can input detailed local data

Input local data and run Input local data and run MOBILE6.2MOBILE6.2 MOBILE6.2 will generate MOBILE6.2 will generate

Emission Factors (EF)Emission Factors (EF) EF are in units of grams EF are in units of grams

per mileper mile EF can be generated for EF can be generated for

NOx, VOC, CO, NHNOx, VOC, CO, NH33, SOx, , SOx, direct PM, brake & tire PM, direct PM, brake & tire PM, and air toxicsand air toxics

Using the appropriate EF:Using the appropriate EF:

Emissions = EF x VMTEmissions = EF x VMT

General ProcedureGeneral Procedure

Required DataRequired Data

Calendar year (1952-2050)Calendar year (1952-2050)

Minimum / maximum temperaturesMinimum / maximum temperatures

Fuel volatility (Reid Vapor Pressure, RVP)Fuel volatility (Reid Vapor Pressure, RVP)

Diesel sulfur contentDiesel sulfur content

Important MOBILE6.2 InputsImportant MOBILE6.2 Inputs

Meteorological dataMeteorological data Minimum and maximum temperaturesMinimum and maximum temperatures Absolute or relative humidityAbsolute or relative humidity Should be consistent with the modeled episodeShould be consistent with the modeled episode

Evaluation monthEvaluation month January (1) or July (7)January (1) or July (7) This only affects the vehicle fleet (i.e. fleet This only affects the vehicle fleet (i.e. fleet

turnover from January to July)turnover from January to July) Typically use January for CO, July for OzoneTypically use January for CO, July for Ozone

Important MOBILE6.2 InputsImportant MOBILE6.2 Inputs

PMPM2.52.5 emissions calculated as annual emissions emissions calculated as annual emissions Requires MOBILE6 run for each month in an Requires MOBILE6 run for each month in an

analysis yearanalysis year Example – Calculating emissions for 2005Example – Calculating emissions for 2005

MonthMonth Cal YearCal Year Eval MonthEval Month MonthMonth Cal YearCal Year Eval MonthEval Month

JanJan 20052005 11 JulJul 20052005 77

FebFeb 20052005 11 AugAug 20052005 77

MarMar 20052005 11 SepSep 20052005 77

AprApr 20052005 77 OctOct 20062006 11

MayMay 20052005 77 NovNov 20062006 11

JunJun 20052005 77 DecDec 20062006 11

Note that RVP may vary by month, as well

Local Data – I/M ProgramLocal Data – I/M Program

Source: State Air AgencySource: State Air Agency What you need to know:What you need to know:

Program type: Two-Speed Idle, ASM, On-Board Program type: Two-Speed Idle, ASM, On-Board Diagnostics (OBD)Diagnostics (OBD)

Vehicle model years coveredVehicle model years covered Actual or anticipated start date of the programActual or anticipated start date of the program Compliance rateCompliance rate Waiver rateWaiver rate

Local Data – VMT MixLocal Data – VMT Mix Source: MPO, DOTSource: MPO, DOT Percentage of VMT generated by Percentage of VMT generated by

different vehicle classes (e.g. different vehicle classes (e.g. passenger cars, light-duty trucks, passenger cars, light-duty trucks, buses, etc.) buses, etc.)

MOBILE6.2 input uses 16 vehicle MOBILE6.2 input uses 16 vehicle classesclasses Local data may not use as many classesLocal data may not use as many classes

You may have to convert! (See You may have to convert! (See Technical Guidance)Technical Guidance)

Each roadway classification can have a Each roadway classification can have a different mixdifferent mix

Local Data – Age Local Data – Age DistributionDistribution

Source: DMV, I/M DataSource: DMV, I/M Data MOBILE6 includes a default MOBILE6 includes a default

percentage of vehicles of each percentage of vehicles of each age from 0 to 25 years oldage from 0 to 25 years old

Vehicles older than 25 years are Vehicles older than 25 years are included with 25-year-old included with 25-year-old vehiclesvehicles

Local data can significantly affect Local data can significantly affect the emission estimatesthe emission estimates

Local Data – Vehicle SpeedsLocal Data – Vehicle Speeds

Source: MPO, DOTSource: MPO, DOT Forecast by travel demand models Forecast by travel demand models

(TDM) or other methods(TDM) or other methods Can be input asCan be input as

One average speed for each road One average speed for each road classification (e.g. Interstate, Other classification (e.g. Interstate, Other freeway, Principal Arterial, Minor freeway, Principal Arterial, Minor Arterial, Collector, Local)Arterial, Collector, Local)

Distribution of speeds on each roadway Distribution of speeds on each roadway for each hour of the dayfor each hour of the day

Local Data – VMTLocal Data – VMT

Source: MPO, DOTSource: MPO, DOT Often forecast by travel demand models (TDM)Often forecast by travel demand models (TDM) If no model: extrapolation of historic traffic countsIf no model: extrapolation of historic traffic counts Typically varies by roadway classification (6 Typically varies by roadway classification (6

Urban and 6 Rural classes)Urban and 6 Rural classes) Reminder: VMT is not a MOBILE6.2 input, but is Reminder: VMT is not a MOBILE6.2 input, but is

used for post-processingused for post-processing

What if you don’t have local What if you don’t have local data?data?

MOBILE6.2 includes national defaults for MOBILE6.2 includes national defaults for almost all inputsalmost all inputs

Minimum data requirementsMinimum data requirements temperature, fuel volatility, and year of temperature, fuel volatility, and year of

evaluationevaluation This will give you a less exact estimate for This will give you a less exact estimate for

your areayour area Use all local data that is available to you and Use all local data that is available to you and

supplement with defaults where necessarysupplement with defaults where necessary

Federal programsFederal programs

Do you need to worry about Tier 2, low Do you need to worry about Tier 2, low sulfur gasoline and the Heavy-Duty Diesel sulfur gasoline and the Heavy-Duty Diesel Rule?Rule?

No. MOBILE6.2 already accounts for No. MOBILE6.2 already accounts for Federal rules.Federal rules.

However, areas required to implement However, areas required to implement reformulated gasoline must specify this reformulated gasoline must specify this input into MOBILE6.2input into MOBILE6.2

Notes on PM EmissionsNotes on PM Emissions

Diesel sulfur content is a required Diesel sulfur content is a required MOBILE6.2 input for PM modelingMOBILE6.2 input for PM modeling

MOBILE6.2 does not calculate re-entrained MOBILE6.2 does not calculate re-entrained road dust or construction dust emissionsroad dust or construction dust emissions There is no approved computer modelThere is no approved computer model Use the methodology in AP-42, Chapter 13, Use the methodology in AP-42, Chapter 13,

“Miscellaneous Sources”“Miscellaneous Sources”

Completing the AnalysisCompleting the Analysis

Average Speed vs. Link-Level AnalysisAverage Speed vs. Link-Level Analysis Average SpeedAverage Speed

Treats each road functional classification as a wholeTreats each road functional classification as a whole Example: One MOBILE6.2 run for freeways with single Example: One MOBILE6.2 run for freeways with single

average freeway speed and VMT mixaverage freeway speed and VMT mix Freeway EF X Total VMT on Freeways = Emissions from Freeway EF X Total VMT on Freeways = Emissions from

freeway vehiclesfreeway vehicles Repeat for arterials, collectors, etc…and sum the totalsRepeat for arterials, collectors, etc…and sum the totals

Completing the AnalysisCompleting the Analysis

Link-LevelLink-Level Multiple MOBILE6.2 runs at different speeds for Multiple MOBILE6.2 runs at different speeds for

each roadway classificationeach roadway classification Create a look-up table of EF based on speed Create a look-up table of EF based on speed

and roadway typeand roadway type Calculate emissions for each segment of Calculate emissions for each segment of

roadway (link) based on classification and roadway (link) based on classification and speedspeed

Sum all of the link emissions together Sum all of the link emissions together

ResourcesResources

From From www.epa.gov/otaq/m6.htmwww.epa.gov/otaq/m6.htm:: MOBILE6.2 User Guide (EPA420-R-03-010)MOBILE6.2 User Guide (EPA420-R-03-010) MOBILE6.2 Policy Guidance (February 24, MOBILE6.2 Policy Guidance (February 24,

2004)2004) Technical Guidance on the Use of MOBILE6.2 Technical Guidance on the Use of MOBILE6.2

for Emission Inventory Preparation (EPA420-R-for Emission Inventory Preparation (EPA420-R-04-013)04-013)

From From www.epa.gov/ttn/chief/ap42/:www.epa.gov/ttn/chief/ap42/: AP-42, Chapter 13, “Miscellaneous Sources”AP-42, Chapter 13, “Miscellaneous Sources”

NONROAD2004NONROAD2004

Airport Ground SupportAirport Ground Support AgriculturalAgricultural ConstructionConstruction CommercialCommercial Lawn & GardenLawn & Garden

LoggingLogging Recreational MarineRecreational Marine ATVsATVs SnowmobilesSnowmobiles Chain SawsChain Saws OthersOthers

• Does not cover Aircraft, Locomotives, or Commercial Marine Vessels

• EPA’s approved emissions model for:

• Used for SIP development and emission inventories

NONROAD2004NONROAD2004

Airport Ground SupportAirport Ground Support AgriculturalAgricultural ConstructionConstruction CommercialCommercial Lawn & GardenLawn & Garden

LoggingLogging Recreational MarineRecreational Marine ATVsATVs SnowmobilesSnowmobiles Chain SawsChain Saws OthersOthers

• Does not cover Aircraft, Locomotives, or Commercial Marine Vessels

• EPA’s approved emissions model for:

• Used for SIP development and emission inventories

NONROAD2004NONROAD2004

Contains national data for all equipment categoriesContains national data for all equipment categories Equipment populationsEquipment populations Load factorsLoad factors Activity levelsActivity levels

Can allocate emissions to the state or county levelCan allocate emissions to the state or county level Calculates emissions by year, season, month, or Calculates emissions by year, season, month, or

dayday Also by weekend or weekdayAlso by weekend or weekday

Can output emissions of NOx, VOC, CO, SOx and Can output emissions of NOx, VOC, CO, SOx and PMPM

NONROAD2004 - Local DataNONROAD2004 - Local Data

Local data always preferredLocal data always preferred Source: SurveysSource: Surveys What data can you improve?What data can you improve?

Population estimatesPopulation estimates Activity estimatesActivity estimates Allocations of equipment use by Allocations of equipment use by

season or day of the weekseason or day of the week

NONROAD2004 - Local DataNONROAD2004 - Local Data

Source: NOAA, local sourcesSource: NOAA, local sources TemperaturesTemperatures Should be consistent with temperatures used Should be consistent with temperatures used

for on-road mobile inventoryfor on-road mobile inventory Source: State Air AgencySource: State Air Agency

Specific fuel parametersSpecific fuel parameters

NONROAD2004 - Local DataNONROAD2004 - Local Data

Local data is inputted by adjusting the Local data is inputted by adjusting the model’s default data filesmodel’s default data files

If sufficient data exists, emissions can be If sufficient data exists, emissions can be sub-allocated from the county to the sub-sub-allocated from the county to the sub-county levelcounty level

EDMSEDMS

FAA’s emissions modelFAA’s emissions model Commercial and general aviation Commercial and general aviation

aircraftaircraft Ground support equipment (also Ground support equipment (also

handled by NONROAD – be handled by NONROAD – be careful not to double-count!)careful not to double-count!)

Airport roadways (may be Airport roadways (may be covered in on-road inventory)covered in on-road inventory)

Can also handle airport stationary Can also handle airport stationary sources and training fires (N/A for sources and training fires (N/A for this purpose)this purpose)

EDMSEDMS

Default dataDefault data Aircraft / engine combinationsAircraft / engine combinations Time-in-mode (e.g. takeoff, climb out, Time-in-mode (e.g. takeoff, climb out,

approach, idle)approach, idle) Ground support equipment by aircraft typeGround support equipment by aircraft type Takeoff weights and approach anglesTakeoff weights and approach angles Mixing height (default 3000 ft above ground Mixing height (default 3000 ft above ground

level (AGL))level (AGL))

EDMS – Local DataEDMS – Local Data

Source: NOAA, local sourceSource: NOAA, local source Average annual temperatureAverage annual temperature Mixing heightMixing height

Source: FAA, Airport AuthoritySource: FAA, Airport Authority Annual Landing-Takeoff (LTO) Annual Landing-Takeoff (LTO)

cycles for each type of aircraft cycles for each type of aircraft (or aircraft / engine combination (or aircraft / engine combination for commercial aircraft)for commercial aircraft)

Annual number of touch-and-Annual number of touch-and-goes (typically general aviation goes (typically general aviation training aircraft)training aircraft)

EDMS - OutputEDMS - Output

Annual emissions of NOx, VOC, CO and Annual emissions of NOx, VOC, CO and SOx for aircraft and ground support SOx for aircraft and ground support equipment (GSE)equipment (GSE)

PM10 for GSE (but not aircraft)PM10 for GSE (but not aircraft) Aircraft PM calculated by hand – limited Aircraft PM calculated by hand – limited

datadata EDMS is also capable of dispersion EDMS is also capable of dispersion

analysis, but that is not necessary for analysis, but that is not necessary for inventory developmentinventory development

LocomotivesLocomotives

Locomotive emissions not Locomotive emissions not covered by a modelcovered by a model

Procedures for Emission Procedures for Emission Inventory Preparation – Inventory Preparation – Volume IV: Mobile Sources, Volume IV: Mobile Sources, page 200page 200

Requires all local dataRequires all local data

Locomotives – Local DataLocomotives – Local Data

Class I, II, and III railroadsClass I, II, and III railroads Line haul and switchyardLine haul and switchyard Line haul calculation:Line haul calculation:

Emissions = Emission Factor x Annual Fuel Emissions = Emission Factor x Annual Fuel UsageUsage

Locomotives – Local DataLocomotives – Local Data

Source: Interview with railroad operatorSource: Interview with railroad operator Class IClass I

Must determine the fuel usage in the nonattainment Must determine the fuel usage in the nonattainment areaarea

Fuel Consumption Index = Systemwide Gross Ton Fuel Consumption Index = Systemwide Gross Ton Miles / Systemwide Fuel ConsumptionMiles / Systemwide Fuel Consumption

Fuel Usage = Fuel Consumption Index * Traffic Fuel Usage = Fuel Consumption Index * Traffic Density in the nonattainment areaDensity in the nonattainment area

Class I railroads should be able to provide this Class I railroads should be able to provide this information (though they may view it as information (though they may view it as confidential)confidential)

Locomotives – Local DataLocomotives – Local Data

Class II & IIIClass II & III Typically smaller railroadsTypically smaller railroads Do not keep same types of records as Class IDo not keep same types of records as Class I May be able to estimate fuel consumed in May be able to estimate fuel consumed in

nonattainment area (e.g. by percentage of nonattainment area (e.g. by percentage of track in the area)track in the area)

All fuel may be consumed in nonattainment All fuel may be consumed in nonattainment areaarea

Locomotives – Local DataLocomotives – Local Data

Switchyard LocomotivesSwitchyard Locomotives Emissions = Number of yard locomotives X Emissions = Number of yard locomotives X

Annual emissions per yard locomotiveAnnual emissions per yard locomotive Sources:Sources:

Interviews with yard operatorsInterviews with yard operators ObservationObservation

Developed as part of the National Emissions Developed as part of the National Emissions Inventory (NEI)Inventory (NEI)

Emissions estimated by multiplying activity by Emissions estimated by multiplying activity by an emission factoran emission factor

Commercial Marine emission factors and Commercial Marine emission factors and methodologies are found inmethodologies are found in Final Regulatory Impact Analysis: Control of Emissions from Final Regulatory Impact Analysis: Control of Emissions from

Marine Diesel Engines (EPA420-R-99-026) for Category 1 Marine Diesel Engines (EPA420-R-99-026) for Category 1 and Category 2 enginesand Category 2 engines

Category 3 Marine Diesel Engines - Final Emission Category 3 Marine Diesel Engines - Final Emission Standards Final Regulatory Support Document (EPA420-R-Standards Final Regulatory Support Document (EPA420-R-03-004) for Category 3 engines03-004) for Category 3 engines

States encouraged to use local port traffic data States encouraged to use local port traffic data to refine the NEI estimatesto refine the NEI estimates

Commercial Marine Commercial Marine VesselsVessels

ResourcesResources

www.epa.gov/otaq/nonrdmdl.htmwww.epa.gov/otaq/nonrdmdl.htm NONROAD2004 (Draft)NONROAD2004 (Draft) Various technical reportsVarious technical reports

www.aee.faa.gov/emissions/EDMS/EDMShome.htmwww.aee.faa.gov/emissions/EDMS/EDMShome.htm EDMS ($45 to purchase)EDMS ($45 to purchase)

www.epa.gov/otaq/invntory.htmwww.epa.gov/otaq/invntory.htm Procedure for Emission Inventory Preparation - Volume IV: Procedure for Emission Inventory Preparation - Volume IV:

Mobile Sources (EPA420-92-009)Mobile Sources (EPA420-92-009) Category 3 Marine Diesel Engines - Final Emission Standards Category 3 Marine Diesel Engines - Final Emission Standards

Final Regulatory Support Document (EPA420-R-03-004)Final Regulatory Support Document (EPA420-R-03-004) Final Regulatory Impact Analysis: Control of Emissions from Final Regulatory Impact Analysis: Control of Emissions from

Marine Diesel Engines (EPA420-R-99-026)Marine Diesel Engines (EPA420-R-99-026)

For More Information…For More Information…

Dale AspyDale Aspy (404) 562-9041(404) 562-9041 aspy.dale@epa.govaspy.dale@epa.gov

Matt LauritaMatt Laurita (404) 562-9044(404) 562-9044 laurita.matthew@epa.govlaurita.matthew@epa.gov