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Emission Factor Modeling

Emission Factor Modeling. Graciela Lubertino, HGAC. What is an Emission Factor?. An emission factor is a rate at which pollution is generated by an on-road source. Reported in grams/mile. Vary by on-road source type and speed. Generated by the EPA MOBILE6 model. What is an on-road source?.

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Emission Factor Modeling

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  1. Emission Factor Modeling Graciela Lubertino, HGAC

  2. What is an Emission Factor? • An emission factor is a rate at which pollution is generated by an on-road source. • Reported in grams/mile. • Vary by on-road source type and speed. • Generated by the EPA MOBILE6 model.

  3. What is an on-road source? • MOBILE6 can model 28 vehicle classes:

  4. What is the MOBILE6 model? • The latest version of the EPA on-road emissions program (MOBILE6.2) • Tool for predicting volatile organic compound (VOC), carbon monoxide (CO), and nitrogen oxide (NOx) emissions • Used for State Implementation Plans (SIPs) and Conformity • Required for use in all states but California

  5. What factors go into MOBILE6? • Model year – impacted by federal engine standards • Gasoline content – oxygenates, sulfur, vapor pressure • Control programs – Inspection and Maintenance • Driving conditions – roadway, speed, air conditioning • Environment – temperature, humidity • Roadway type – freeway, arterial, ramp, local

  6. What factors does MOBILE6 calculate? • Combustion – VOC, NOx, CO - Running exhaust - Start emissions • Evaporative – VOC - resting: hot soak, diurnal, resting losses - running: crankcase, running losses

  7. How does MOBILE6 represent local conditions? • Through the use of local data inputs: • Registration distribution • Vehicle Miles of Travel (VMT) Mix • Local travel data • Local control programs (I/M, anti-tampering programs) • Local atmospheric data • Diesel fractions

  8. What do these emission factors look like? Vehicle Type: LDGV Year: 2007 Speed: 25 mph ------------------------------------------------------------------- Composite Emission Factors (g/mi): Composite VOC : 0.684 Composite CO : 6.18 Composite NOX : 0.535 -------------------------------------------------------------------

  9. So where is the problem? • The number of miles driven. • Example: composite NOx EF = 1.4 g/mile 134 million miles of travel per day = 187,600,000 grams per day = 206 tons of NOx per day • 2007 On-Road Budget in the SIP • NOx: 186.13 tons per day • VOC: 89.99 tons per day

  10. How do emission factors become an emission inventory? • Emission factors are generated for: • Each hour, each county, all speeds, all vehicle categories, all roadway types • These are combined with the VMT data out of the Travel Demand model, resulting in emissions by: • County, roadway, pollutant, and hour

  11. Conformity Analysis Summary-Draft

  12. What else can MOBILE6 do? • MOBILE6.2 can also model: • Toxics. This category includes certain metals, particulates, and organic compounds. • Particulate matter, both PM10 and PM2.5. • Carbon Dioxide, a greenhouse gas.

  13. Questions?

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