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.

  1. 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.

  2. 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.

  3. 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 distribution circuits may need upgrading if they are to serve clusters of PHEVs. Encouraging PHEV owners to charge their vehicles during off-peak hours will require both rate schedules that reward time-appropriate charging and equipment that can monitor—or even control—time of use.

  4. 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.

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