2014/07/16 Council Agenda Packet

this analysis we assumed that any increases in the number of "traditional" hybrid electric vehicles (not plug-in hybrid electric vehicles) would be captured with the overall improvements to the average fuel economy of the fleet. As mentioned above, we were not able to adjust for these improvements within the emissions model, and there is no methodology available to apply an adjustment to the emissions output or to individual emission factors. From the NHTSA Draft Environmental Impact State (DEIS) for the proposed CAFE standards, these standards are expected to reduce grams CO2e per mile from 295 in the base year fleet to 250 grams CO2e per mile, a 15.3% improvement. Data on the other alternatives analyzed in the NHTSA DEIS suggest that a combined fleet average of 38.7 mpg, which is the alternative closest to our Likely Scenario assumption, would result in an 18.3% reduction from the existing fleet. As a comparison, the alternative closest to the proposed CAFE standards of 35.5 mpg resulted in a reduction of 14.5%. Data was not readily available for a 50 mpg fleet average, which is our Aggressive Scenario. While Growing Cooler does report on a 50 mpg scenario, their calculations have built-in assumptions regarding national VMT growth, and are not easily transferrable for a post -processing application to Transportation 2040. Based on the research conducted, we chose the following application of our Likely and Aggressive Scenarios: ■ Likely Scenario (40 mpg): an 18% reduction was applied to the greenhouse gas emissions results from Transportation 2040 for the remainder of the passenger cars and light trucks. This is based on the analysis of the alternative in the NHTSA DEIS which is closest to this scenario, at a combined fleet average of 38.7 mpg. • Aggressive Scenario (50 mpg): a 25% reduction was applied to the greenhouse gas emissions results from Transportation 2040 for the remainder of the passenger cars and light trucks. In the absence of specific data that can be applied to our results, we compared the varying reduction of emissions from the NHTSA DEIS alternatives and used this as a factor for our Aggressive Scenario assumptions. For example, the difference in greenhouse gas emissions between a combined fleet average of 35.5 mpg and a fleet average of 38.7 mpg standard in the NHTSA DEIS is approximately 4%. As such, to maintain consistency and reasonableness in the application of our assumptions, we forecasted an additional 8% reduction between a combined fleet average of 40 mpg and 50 mpg. We believe this is a fairly conservative application of our assumptions. For example, EPA's "A Wedge Analysis of the U.S. Transportation Sector" study indicates that hybrid electric vehicles achieve a 29% reduction in greenhouse gas emissions over traditional gasoline vehicles; as a comparison, we are applying only a 25% reduction factor for a combined fleet average of 50 mpg. 2C. Reduction of Carbon Intensity of Fuels (i.e., Alternative Fuels) • Likely Scenario: 10% • Aggressive Scenario: 25% As discussed in Section 1, the scenarios for reducing the carbon intensity of the fuel supply have the most potential for overlap with the other components of the technology assumptions. As such, for the application of these scenarios to Transportation 2040, we wanted to ensure that we did not overestimate, or double count, the benefits from this strategy. Based on the research conducted, however, it does seem likely that at least some portion of the implementation strategy will be achieved through alternative fuels such as ethanol, biodiesel, etc., and therefore additional reductions may be achieved above and beyond the reductions assumed from improved fuel economy and electric vehicles. To remain as conservative and reasonable as possible, therefore, the following adjustments were applied to the greenhouse gas emission results from Transportation 2040 for the remainder of the passenger vehicle fleet, after the reductions from 2A and 2B were applied: • Likely Scenario (10%): a 5% reduction was applied to the greenhouse gas emission results from Transportation 2040 for the remainder of the passenger cars and light trucks. This is an adjustment of 50% from the scenario assumption of a 10% benefit from this strategy. L-8 Appendix L: Climate Change Background