Transitions to Alternative Transportation Technologies—Plug-in Hybrid Electric Vehicles (2010)

Lithium-ion battery technology has been developing rapidly, especially at the cell level, but costs are still high, and the potential for dramatic reductions appears limited. Assembled battery packs currently cost about $1,250 to $1,700 per kWh of usable energy ($625 to $850/kWh of nameplate energy). A PHEV-10 will require about 2.0 kWh and a PHEV-40 about 8 kWh even after the batteries have undergone expected degradation over time. Costs are expected to decline by about 35 percent by 2020 but more slowly thereafter. Projections of future battery pack costs are uncertain, as they depend on the rate of improvements in battery technology and manufacturing techniques, potential breakthroughs in new technology, possible relaxation of battery protection parameters as experience is gained, and the level of production, among other factors. Further research is needed to reduce costs and achieve breakthroughs in battery technology.

Costs to a vehicle manufacturer for a PHEV-40 built in 2010 are likely to be about $14,000 to $18,000 more than an equivalent conventional vehicle, including a $10,000 to $14,000 battery pack. The incremental cost of a PHEV-10 would be about $5,500 to $6,300, including a $2,500 to $3,300 battery pack. In addition, some homes will require electrical system upgrades, which might cost more than $1,000. In comparison, the incremental cost of an HEV might be $3,000.

PHEV-40s are unlikely to achieve cost-effectiveness before 2040 at gasoline prices below $4.00 per gallon, but PHEV-10s may get there before 2030. PHEVs will recoup some of their incremental cost, because a mile driven on electricity will be cheaper than a mile on gasoline, but it is likely to be several decades before lifetime fuel savings start to balance the higher first cost of the vehicles. Subsidies of tens to hundreds of billions of dollars will be needed for the transition to cost-effectiveness. Higher oil prices or rapid reductions in battery costs could reduce the time and subsidies required to attain cost-effectiveness.

At the Maximum Practical rate, as many as 40 million PHEVs could be on the road by 2030, but various factors (e.g., high costs of batteries, modest gasoline savings, limited availability of places to plug in, competition from other vehicles, and consumer resistance to plugging in virtually every day) are likely to keep the number lower. The Maximum Practical rate depends on rapid technological progress, increased government support, and consumer acceptance. A more realistic penetration rate would result in 13 million PHEVs by 2030 out of about 300 million vehicles on the road, which still assumes that current levels of government support will continue for several decades.

PHEVs will have little impact on oil consumption before 2030 because there will not be enough of them in the fleet. More substantial reductions could be achieved by 2050. PHEV-10s will reduce oil consumption only slightly more than can be achieved by HEVs. A PHEV-10 is expected to use about 20 percent less gasoline than an equivalent HEV, saving about 70 gallons in 15,000 miles. Forty million PHEV-10s would save a total of about 0.2 million barrels of oil per day. The current light-duty vehicle fleet uses about 9 million barrels per day. PHEV-40s will consume about 55 percent less gasoline than equivalent HEVs, saving more than 200 gallons of gasoline per year per vehicle.

PHEV-10s will emit less carbon dioxide than non-hybrid vehicles, but save little relative to HEVs after accounting for emissions at the generating stations that supply the electric power. PHEV-40s are more effective than PHEV-10s, but the GHG benefits are small unless the grid is decarbonized with renewable energy, nuclear plants, or fossil fuel fired plants equipped with carbon capture and storage systems.

No major problems are likely to be encountered for several decades in supplying the power to charge PHEVs, as long as most vehicles are charged at night. Generation and transmission of electricity during off-peak hours should be adequate for many millions of PHEVs, although some

A portfolio approach to research, development, demonstration, and, perhaps, market transition support is essential. It is not clear what technology or combination of technologies—batteries, hydrogen, or biofuels—will be most effective in reducing the nation's oil dependency to levels that may be necessary in the long run. It is clear, however, that a portfolio approach will enable the greatest reduction in oil use. Increasing the efficiency of conventional vehicles (including HEVs) beyond the current regulatory framework could reduce gasoline consumption by about 40 percent in 2050, compared to the Reference Case. Adding biofuels would reduce it another 20 percent. If PHEV-10s are also included at the Maximum Practical rate, gasoline consumption would be reduced an additional 7 percent, while PHEV-40s could reduce consumption by 23 percent. Employing HFCVs instead of PHEVs could eliminate gasoline use by the fleet.