Mobile Source Inventories for SIPs

1. Mobile Source Inventories for SIPs Matt Laurita Air Quality Modeling and Transportation Section EPA Region 4

2. What You Need • MOBILE6.2 model • “Technical Guidance on the Use of MOBILE6 for Emission Inventory Preparation” • Vehicle Miles Traveled (VMT) and Speeds • Base year and estimated future values • Local data • Fleet age distribution, fleet mix, meteorological data • Control programs • Inspection & Maintenance (I/M), anti-tampering, etc… • For PM2.5: AP-42, Chapter 13

3. What You Need • NONROAD2004 Model • Emissions and Dispersion Modeling System (EDMS) Model • “Procedures for Emission Inventory Preparation – Volume IV: Mobile Sources” (EPA420-92-009) • Category 3 Marine Diesel Engines - Final Emission Standards Final Regulatory Support Document (EPA420-R-03-004) • Final Regulatory Impact Analysis: Control of Emissions from Marine Diesel Engines (EPA420-R-99-026)

4. MOBILE6.2 • EPA’s approved motor vehicle emissions model • MOBILE6.2 is used for • SIP development • Transportation conformity • Emission inventories • Special studies

5. MOBILE6.2 • Computer model that predicts vehicle emissions on a grams per mile basis • Freely available (download) • DOS based • Contains default national data on fleet mix, average speeds, age distributions, etc… • User can input detailed local data

6. General Procedure • Input local data and run MOBILE6.2 • MOBILE6.2 will generate Emission Factors (EF) • EF are in units of grams per mile • EF can be generated for NOx, VOC, CO, NH3, SOx, direct PM, brake & tire PM, and air toxics • Using the appropriate EF: Emissions = EF x VMT

7. Required Data • Calendar year (1952-2050) • Minimum / maximum temperatures • Fuel volatility (Reid Vapor Pressure, RVP) • Diesel sulfur content

8. Important MOBILE6.2 Inputs • Meteorological data • Minimum and maximum temperatures • Absolute or relative humidity • Should be consistent with the modeled episode • Evaluation month • January (1) or July (7) • This only affects the vehicle fleet (i.e. fleet turnover from January to July) • Typically use January for CO, July for Ozone

9. Important MOBILE6.2 Inputs • PM2.5 emissions calculated as annual emissions • Requires MOBILE6 run for each month in an analysis year • Example – Calculating emissions for 2005 Note that RVP may vary by month, as well

10. Local Data – I/M Program • Source: State Air Agency • What you need to know: • Program type: Two-Speed Idle, ASM, On-Board Diagnostics (OBD) • Vehicle model years covered • Actual or anticipated start date of the program • Compliance rate • Waiver rate

11. Local Data – VMT Mix • Source: MPO, DOT • Percentage of VMT generated by different vehicle classes (e.g. passenger cars, light-duty trucks, buses, etc.) • MOBILE6.2 input uses 16 vehicle classes • Local data may not use as many classes • You may have to convert! (See Technical Guidance) • Each roadway classification can have a different mix

12. Local Data – Age Distribution • Source: DMV, I/M Data • MOBILE6 includes a default percentage of vehicles of each age from 0 to 25 years old • Vehicles older than 25 years are included with 25-year-old vehicles • Local data can significantly affect the emission estimates

13. Local Data – Vehicle Speeds • Source: MPO, DOT • Forecast by travel demand models (TDM) or other methods • Can be input as • One average speed for each road classification (e.g. Interstate, Other freeway, Principal Arterial, Minor Arterial, Collector, Local) • Distribution of speeds on each roadway for each hour of the day

14. Local Data – VMT • Source: MPO, DOT • Often forecast by travel demand models (TDM) • If no model: extrapolation of historic traffic counts • Typically varies by roadway classification (6 Urban and 6 Rural classes) • Reminder: VMT is not a MOBILE6.2 input, but is used for post-processing

15. What if you don’t have local data? • MOBILE6.2 includes national defaults for almost all inputs • Minimum data requirements • temperature, fuel volatility, and year of evaluation • This will give you a less exact estimate for your area • Use all local data that is available to you and supplement with defaults where necessary

16. Federal programs • Do you need to worry about Tier 2, low sulfur gasoline and the Heavy-Duty Diesel Rule? • No. MOBILE6.2 already accounts for Federal rules. • However, areas required to implement reformulated gasoline must specify this input into MOBILE6.2

17. Notes on PM Emissions • Diesel sulfur content is a required MOBILE6.2 input for PM modeling • MOBILE6.2 does not calculate re-entrained road dust or construction dust emissions • There is no approved computer model • Use the methodology in AP-42, Chapter 13, “Miscellaneous Sources”

18. Completing the Analysis • Average Speed vs. Link-Level Analysis • Average Speed • Treats each road functional classification as a whole • Example: One MOBILE6.2 run for freeways with single average freeway speed and VMT mix • Freeway EF X Total VMT on Freeways = Emissions from freeway vehicles • Repeat for arterials, collectors, etc…and sum the totals

19. Completing the Analysis • Link-Level • Multiple MOBILE6.2 runs at different speeds for each roadway classification • Create a look-up table of EF based on speed and roadway type • Calculate emissions for each segment of roadway (link) based on classification and speed • Sum all of the link emissions together

20. Resources • From www.epa.gov/otaq/m6.htm: • MOBILE6.2 User Guide (EPA420-R-03-010) • MOBILE6.2 Policy Guidance (February 24, 2004) • Technical Guidance on the Use of MOBILE6.2 for Emission Inventory Preparation (EPA420-R-04-013) • From www.epa.gov/ttn/chief/ap42/: • AP-42, Chapter 13, “Miscellaneous Sources”

21. Airport Ground Support Agricultural Construction Commercial Lawn & Garden Logging Recreational Marine ATVs Snowmobiles Chain Saws Others NONROAD2004 • EPA’s approved emissions model for: • Used for SIP development and emission inventories • Does not cover Aircraft, Locomotives, or Commercial Marine Vessels

22. Airport Ground Support Agricultural Construction Commercial Lawn & Garden Logging Recreational Marine ATVs Snowmobiles Chain Saws Others NONROAD2004 • EPA’s approved emissions model for: • Used for SIP development and emission inventories • Does not cover Aircraft, Locomotives, or Commercial Marine Vessels

23. NONROAD2004 • Contains national data for all equipment categories • Equipment populations • Load factors • Activity levels • Can allocate emissions to the state or county level • Calculates emissions by year, season, month, or day • Also by weekend or weekday • Can output emissions of NOx, VOC, CO, SOx and PM

24. NONROAD2004 - Local Data • Local data always preferred • Source: Surveys • What data can you improve? • Population estimates • Activity estimates • Allocations of equipment use by season or day of the week

25. NONROAD2004 - Local Data • Source: NOAA, local sources • Temperatures • Should be consistent with temperatures used for on-road mobile inventory • Source: State Air Agency • Specific fuel parameters

26. NONROAD2004 - Local Data • Local data is inputted by adjusting the model’s default data files • If sufficient data exists, emissions can be sub-allocated from the county to the sub-county level

27. EDMS • FAA’s emissions model • Commercial and general aviation aircraft • Ground support equipment (also handled by NONROAD – be careful not to double-count!) • Airport roadways (may be covered in on-road inventory) • Can also handle airport stationary sources and training fires (N/A for this purpose)

28. EDMS • Default data • Aircraft / engine combinations • Time-in-mode (e.g. takeoff, climb out, approach, idle) • Ground support equipment by aircraft type • Takeoff weights and approach angles • Mixing height (default 3000 ft above ground level (AGL))

29. EDMS – Local Data • Source: NOAA, local source • Average annual temperature • Mixing height • Source: FAA, Airport Authority • Annual Landing-Takeoff (LTO) cycles for each type of aircraft (or aircraft / engine combination for commercial aircraft) • Annual number of touch-and-goes (typically general aviation training aircraft)

30. EDMS - Output • Annual emissions of NOx, VOC, CO and SOx for aircraft and ground support equipment (GSE) • PM10 for GSE (but not aircraft) • Aircraft PM calculated by hand – limited data • EDMS is also capable of dispersion analysis, but that is not necessary for inventory development

31. Locomotives • Locomotive emissions not covered by a model • Procedures for Emission Inventory Preparation – Volume IV: Mobile Sources, page 200 • Requires all local data

32. Locomotives – Local Data • Class I, II, and III railroads • Line haul and switchyard • Line haul calculation: • Emissions = Emission Factor x Annual Fuel Usage

33. Locomotives – Local Data • Source: Interview with railroad operator • Class I • Must determine the fuel usage in the nonattainment area • Fuel Consumption Index = Systemwide Gross Ton Miles / Systemwide Fuel Consumption • Fuel Usage = Fuel Consumption Index * Traffic Density in the nonattainment area • Class I railroads should be able to provide this information (though they may view it as confidential)

34. Locomotives – Local Data • Class II & III • Typically smaller railroads • Do not keep same types of records as Class I • May be able to estimate fuel consumed in nonattainment area (e.g. by percentage of track in the area) • All fuel may be consumed in nonattainment area

35. Locomotives – Local Data • Switchyard Locomotives • Emissions = Number of yard locomotives X Annual emissions per yard locomotive • Sources: • Interviews with yard operators • Observation

36. Commercial Marine Vessels • Developed as part of the National Emissions Inventory (NEI) • Emissions estimated by multiplying activity by an emission factor • Commercial Marine emission factors and methodologies are found in • Final Regulatory Impact Analysis: Control of Emissions from Marine Diesel Engines (EPA420-R-99-026) for Category 1 and Category 2 engines • Category 3 Marine Diesel Engines - Final Emission Standards Final Regulatory Support Document (EPA420-R-03-004) for Category 3 engines • States encouraged to use local port traffic data to refine the NEI estimates

37. Resources • www.epa.gov/otaq/nonrdmdl.htm • NONROAD2004 (Draft) • Various technical reports • www.aee.faa.gov/emissions/EDMS/EDMShome.htm • EDMS ($45 to purchase) • www.epa.gov/otaq/invntory.htm • Procedure for Emission Inventory Preparation - Volume IV: Mobile Sources (EPA420-92-009) • Category 3 Marine Diesel Engines - Final Emission Standards Final Regulatory Support Document (EPA420-R-03-004) • Final Regulatory Impact Analysis: Control of Emissions from Marine Diesel Engines (EPA420-R-99-026)

38. For More Information… • Dale Aspy • (404) 562-9041 • aspy.dale@epa.gov • Matt Laurita • (404) 562-9044 • laurita.matthew@epa.gov