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It’s Easy to Quantify Changes in GHG Emissions from Cars and Light Trucks – Right?

It’s Easy to Quantify Changes in GHG Emissions from Cars and Light Trucks – Right?. Presented to: SACOG Panel Discussion April 16, 2009 Presented by: Bob Dulla Sierra Research. Background. AB 32 AB 1493 SB 375. Vehicle GHG Emissions.

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It’s Easy to Quantify Changes in GHG Emissions from Cars and Light Trucks – Right?

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  1. It’s Easy to Quantify Changes in GHG Emissions fromCars and Light Trucks – Right? Presented to: SACOG Panel Discussion April 16, 2009 Presented by: Bob Dulla Sierra Research

  2. Background • AB 32 • AB 1493 • SB 375

  3. Vehicle GHG Emissions

  4. Greenhouse Gas Emissionsfrom Passenger Cars(Assumes 27.5 mpg)

  5. Historical and Projected Light-Duty Vehicle Fuel Economy Standards1978-2020

  6. Range of Average Vehicle Class MPGin 2006 Model Year

  7. Key Points • All vehicles within the same class/model year meet the same criteria pollutant standard • Substitution of a small car for a large car has no impact on criteria pollutant emissions • Wide diversity in fuel economy (GHG) emissions within same class/model year • Substitution of a small car for a large car can significantly reduce GHG emissions • Tracking GHG impacts of vehicle substitution requires more detailed information

  8. Transportation Options to Reduce GHGs • Signal timing improvements • Increased carpooling • Trip reductions • Increased use of transit • Greater utilization of existing fuel efficient vehicles • Changes in land use • Vehicle scrappage • ?

  9. Traditional Metrics Used toQuantify Motor Vehicle Emissions • Travel Models Supply • Trips (starting and evaporative emissions) • Link specific VMT (running emissions) • Link specific speed (running emissions) • EMFAC Supplies • Emission rates (g/trip or g/mi) by vehicle class and model year • Correction factors (e.g., speed, temperature, etc.) • Relative share of travel across vehicle classes

  10. What Does EMFAC Supply forGHG Calculations? • GHG emission rates (g/mi) by vehicle class and model year • Speed correction factors for portions of the vehicle fleet • Travel activity data (consistent with MPO projections)

  11. The Effect of Speed on GasolinePowered Vehicle Emissions

  12. What is Missing? • No subclass specific GHG values • No forecast of fleet improvements (e.g., CAFE or AB 1493) • No GHG speed correction for most HDVs (only HHDDVs)

  13. GHG Control Measures that CannotBe Quantified • Increased utilization of fuel efficient vehicles • Shift from truck to car can be quantified • Shift from large car to small car cannot • All measures in future years (no forecast of CAFE improvements)

  14. What’s Needed to Address this Shortfall? • Forecast of annual changes in GHGs by vehicle class • Distribution of GHGs within vehicle class/model year • Vehicle class specific speed correction factors • Information on household vehicle mix

  15. How are Statewide GHG Inventories Currently Calculated? • EMFAC based CO2 equivalent • EMFAC based fuel consumption • Adjustment for EMFAC vs. FHWA tax based fuel consumption estimate

  16. Issues to Consider in EstimatingGHG Emissions • How well do average annual weekday travel estimates translate to annual estimates of GHG emissions? • Weekday vs. weekend • Heavy truck travel activity • Household vehicle utilization rates • Can or should GHG emission estimates be developed within the criteria pollutant framework? • Is local fuel use ever used to assess or validate local travel estimates? • Need for MPO/ARB GHG model coordination

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