General Motors plans to launch the Volt plug-in hybrid electric vehicle later this year. It will be able to travel 40 miles on battery power before the gasoline engine kicks in to finish the trip. Then it can be plugged into an electric outlet to charge up for another 40 miles. Toyota will follow with a plug-in version of the Prius hybrid by 2011, which may have an electric range of 10 to 15 miles. Many other large auto companies have also announced plans to mass produce their own electric plug-in vehicles in the near future. According to a new report from the National Research Council, however, these vehicles are unlikely to have a major impact on U.S. oil dependence or on transportation greenhouse gas emissions until tens of millions of them are on the road, which will take decades.
The primary hurdle to widespread adoption of plug-in vehicles is the bill. According to the report, manufacturing costs for a first generation plug-in hybrid with a 10-mile range (PHEV-10) is likely to be about $6,000 more than for an equivalent conventional vehicle, while a PHEV-40 could cost $14,000 to $18,000 more. The cost of batteries, the major contributor to these costs, is declining, but dramatic reductions are unlikely without major technological breakthroughs. In addition, the electrical system upgrades needed for some homes would add to the overall price tag of purchasing a plug-in.
Aside from the high cost, there are additional challenges in transitioning the U.S. automotive market toward a new technology like electric plug-ins. The nationwide electrical grid would need to be up to the task of charging millions of vehicles. For now, while the number of these vehicles on the road remains low, the grid is expected to be able to handle the additional demand, especially if people charge their vehicles at night during off-peak hours. Other factors, such as difficulty finding places to plug in while traveling and consumer resistance to having to remember to plug their car in every day, will also play a part in slowing adoption of this new technology. According to the report, a realistic penetration rate by 2030 would be approximately 13 million plug-in vehicles -- out of 300 million total vehicles on the road.
PHEVs save a significant amount of gasoline relative to conventional vehicles, but compared with current hybrids capable of achieving 40 miles per gallon, a PHEV-10 saves less than 20 percent or about 70 gallons per year for the typical driver. Therefore, 13 million PHEV-10s would save about 60,000 barrels of gasoline per day; U.S. consumption of gasoline is about 9 million barrels per day. PHEV-40s do better, saving about 55 percent, but at much higher cost. As more and more plug-ins enter the market, the savings would add up and could become substantial by 2050, the report says.
PHEVs will reduce emissions of carbon dioxide even less than the consumption of gasoline, because lowered emissions from the car are partially offset by the emissions produced at fossil-fuel powered electricity generating stations. Emission reductions could become significant if the electricity can be produced from nuclear power plants, renewable energy technologies, or fossil-fuel powered plants with carbon capture and storage capability.
Plug-in vehicles are one of several technologies -- including hydrogen vehicles and biofuels -- in development to aid in reducing the nation's oil dependence. The best approach, the report says, would be to make plug-ins part of a larger portfolio of research, development, and demonstration, as it is not yet clear which technology, or combination of technologies, will be most effective. — Rebecca Alvania
Transitions to Alternative Transportation Technologies -- Plug-in Hybrid Electric Vehicles. Committee on Assessment of Resource Needs for Fuel Cell and Hydrogen Technologies, Board on Energy and Environmental Systems, Division on Engineering and Physical Sciences (2010, approx. 130 pp.; ISBN 0-309-14850-2; available from the National Academies Press, tel. 1-800-624-6242; $32.00 plus $5.00 shipping for single copies).
The committee was chaired by Mike Ramage, retired executive vice president, ExxonMobil Research and Engineering Co. The study was funded by the U.S. Department of Energy.