California ARB Details Refutation of EPA Claim that New Federal CAFE Is More Effective at GHG Reduction than AB1493

3 January 2008

Comparison of the cumulative greenhouse gas reductions of AB1493 (Pavley Regulation) and the CAFE standards if implemented in California, using the California fleet mix. Click to enlarge.

In public comments concerning the denial of the waiver that would have cleared the way for California and the other adopting states to enforce the AB1493 rules (Pavley Regulation) regulating greenhouse gas emissions from light duty vehicles (earlier post), EPA Administrator Stephen Johnson claimed that the new federal CAFE standards would be more effective than the California rules in reducing greenhouse gas emissions.

The California Air Resources Board’s (ARB) staff prepared and documented its own technical evaluation refuting Johnson’s claim, which was undocumented. The ARB study shows that California’s regulations on tailpipe greenhouse gas emissions are more effective than the new CAFE regulations contained in federal energy bill.

California standards regulate GHG emissions; federal CAFE standards are aimed at reducing the nation’s fuel consumption. This study makes the necessary calculations to allow the two programs to be evaluated so that the reductions in GHG gases under the California rules can be compared to those expected from implementation of the CAFE portion of the 2007 Energy Bill. The results show that the Administrator’s claim that the federal CAFE program is better than California’s program at reducing GHG emissions from motor vehicles is wrong, both in California and in those states that adopt the California standards.

Comparison of projected fleet fuel economies resulting from application of California Pavley and federal CAFE to California and federal new fleet mixes. Click to enlarge.

In its analysis, ARB employed both the miles per gallon metric used in the 2007 Energy Bill and the GHG emissions rates that are the basis of California’s regulation. ARB staff translated, as best as possible, miles per gallon to equivalent GHG emission rates. ARB staff then used the EMFAC on-road emissions inventory model to develop an apples-to-apples comparison of tons of greenhouse gases reduced under the federal CAFE standards to those that occur under the Pavley rules.

...by 2016, the adopted Pavley rules will have prevented a total of 58 MMT of CO₂ from being emitted into the air [in California] as compared to 20 MMT if the new Federal standards were implemented. By 2020, the combination of the Pavley 1 and 2 rules will have prevented 167 MMT of CO₂ emissions from being emitted as compared to 76 MMT of CO₂ if only the Federal CAFE were implemented.

The EMFAC model reflects the current and projected vehicle fleet in California, based on data from the Department of Motor Vehicles, the Smog Check inspection and maintenance program, and local and regional transportation planning agencies. The emission rates in the EMFAC model are derived from testing of in-use vehicles.

ARB distributed total vehicle miles travelled (VMT) estimates among the vehicle classes using DMV population data and mileage accrual rates obtained from the Smog Check program.

The 2007 Energy Bill that enables the new CAFE standards also provides for a fuel economy credit for vehicles that are capable of operating on alternative fuels such as E85. Since manufacturers have indicated that they will produce large numbers of flex-fuel vehicles capable of operating on E85, ARB staff believes that manufacturers are likely to take full advantage of the credit between 2011 and 2019. The analysis includes this assumption in the calculation of the benefits of the new CAFE standards on GHG reductions.

The analysis also looked at GHG emission reductions achievable not only in California with the existing AB1493 (the Pavley Phase 1 rules) but also those expected when the ARB extends the existing requirements to obtain further reductions in the 2017 to 2020 timeframe (referred to as the Pavley Phase 2 rules).

The analysis shows that the California CO₂ emission standards are 16% more stringent for 2016 models and 18% more stringent for 2020 models than under the new federal CAFE.

ARB calculated that for the projected mix of the California fleet, the Pavley Phase 1 rules would increase the average fuel economy to 36.6 mpg by 2016; under Federal CAFE, the CA fleet mix would show a 30.5 mpg new fleet fuel economy in 2016.

ARB projected that Pavley Phase 2 rules would increase that new fleet mpg to 43.9 mpg by 2020; federal CAFE would take the California fleet mix to 35.7 mpg by 2020.

ARB also applied the analysis to the federal fleet mix. (The Federal fleet is assumed to have 50% passenger cars/LDT1 trucks and 50% LDT2 trucks. This compares to 70% passenger cars/LDT1 trucks and 30% LDT2 trucks for the California fleet.)

For the federal fleet mix, Pavley Phase 1 resulted in 33.1 mpg by 2016, compared to 29.6 mpg for Federal CAFE. By 2020, the Pavley rules would deliver 40.4 mpg in the federal fleet, while CAFE results in the targeted 35 mpg.

California has filed suit against the EPA to overturn the denial. (Earlier post.)

Resources

• Comparison of Greenhouse Gas Reductions Under CAFE Standards and ARB Regulations Adopted Pursuant to AB1493