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Transitions to Alternative Transportation Technologies—Plug-In Hybrid Electric Vehicles
TABLE S.1 Estimated Future PHEV Incremental Costs
NOTE: These are the incremental costs to manufacture the vehicle itself, relative to a conventional (nonhybrid) vehicle. They do not include engineering, overhead, or other costs, or profit, and thus are not the total incremental prices to the customer. Costs for 2011 are based on low battery production rates in response to contracts initiated about 2 years earlier. Ranges represent probable and optimistic assessments of battery technology progress. Additional detail on the committee’s analysis of battery-pack cost can be found in Appendix F, which was added to this report after release of the prepublication version to clarify how the estimates were made.
It is possible that breakthroughs in battery technology will greatly lower the cost. At this point, however, it is not clear what sorts of breakthroughs might become commercially viable. Furthermore, even if they occur within the next decade, they are unlikely to have much impact before 2030, because it takes many years to get large numbers of vehicles incorporating new technology on the road.
Electric Power Infrastructure Issues
PHEVs replace gasoline with electricity for some of the miles driven. The electricity will first have to be generated and then delivered to a PHEV through the electric grid. This raises two issues: (1) whether sufficient generation, transmission, and distribution capacity will be available to serve this additional load and (2) how the emissions from the additional electricity generation compare with the emissions from the gasoline not consumed.
Grid capacity will be available to charge millions of PHEVs if they are charged at night. Power demand varies during the day, peaking during the afternoon and reaching a low point after midnight. It also varies over the year, with demand highest on summer afternoons because of air conditioning loads. Parts of the U.S. electric power system are at full capacity during these hours of highest demand, and additional loads could threaten reliability unless new capacity is added. At night, however, the system may operate at less than 50 percent of capacity, and the cost of producing electricity is much lower than during peak hours. Drivers paying a constant rate per kilowatt-hour of electricity are likely to charge their vehicles whenever they have convenient access to an electric outlet, potentially increasing electricity demand during peak hours. Smart meters with time-of-use pricing would be one way of encouraging drivers to delay charging until electricity demand is lower.
Generating electricity to replace the gasoline that a car would have used emits some greenhouse gases (GHG), especially CO2. About half the nation’s electricity is produced from coal-fired power plants, which are large emitters of CO2. However, the overall efficiency of electric vehicles is greater than that of conventional vehicles, so emissions may be reduced to some extent. Large savings on emissions will require decarbonizing the electric system, such as by using nuclear power or renewable energy generation or by capturing and sequestering the CO2 emitted by fossil fuel plants.
Penetration rates for the PHEV-10 and the PHEV-40 were compared to a Reference Case that assumes high oil prices and fuel economy standards specified by the Energy Independence and Security Act of 2007 (with modest increases after 2020, when those standards level off), as described in the 2008 Hydrogen Report. The Maximum Practical scenario is the fastest rate at which the committee concluded that PHEVs could penetrate the market considering various manufacturing and market barriers; it leads to about 40 million PHEVs by 2030 in a fleet of about 300 million vehicles.2 A more probable scenario leads to about 13 million PHEVs by 2030. Figure S.1 shows the number of PHEVs on the road at the two rates.
Figure S.2 shows the impact on gasoline use relative to the Reference Case when each of the two PHEV types is introduced at the Maximum Practical rate into a high-efficiency fleet. The Efficiency Case fleet, based on Case 2 from the 2008 Hydrogen Report, includes conventional nonhybrid vehicles and HEVs only. All cases give results similar to the Reference Case until after 2020, because it takes many years for a sufficient number of new vehicles to penetrate the market to have an impact. By 2030, the Efficiency and PHEV cases show gasoline consumption well below the Reference Case. PHEV-10 closely follows the Efficiency Case until 2040, after which it shows some additional benefit. PHEV-40 shows benefits relative to the Efficiency Case after 2025.
Figure S.3 shows the well-to-wheels GHG emissions of the light-duty vehicle fleet for the PHEV scenarios and compares them to the Reference Case. PHEVs show less improvement in GHG emissions than in gasoline consumption because of the additional emissions from electricity generation. If carbon emissions from the electric sector are limited, the reductions in Figure S.3 would be greater, almost following the reductions in gasoline use in Figure S.2.
This scenario is based on the Hydrogen Success scenario in the 2008 Hydrogen Report but moved up 3 years because battery technology is more nearly ready for commercialization than fuel cells.