Electrical grid could handle millions of plug-in hybrids

A new study, conducted by the Pacific Northwest National Laboratories and sponsored by the federal agency, predicts that off-peak electricity production is adequate for keeping 185 million plug-in hybrids on the road. The study stated that there are 220 million vehicles in the U.S. and, if all were converted to plug-in hybrids, the current electrical grid could keep 84 percent of them charged.

Plug-in hybrids have electrical and gas motors. The batteries for running the electric motor in plug-ins, however, are charged by plugging them into wall sockets or chargers. Plug-ins can drive for longer distances than standard electric cars because they have a gas motor, but get far better mileage--100 miles per gallon in some cases--than standard hybrids because the electric motor does a larger proportion of the work.

Plug-ins also result in lower tailpipe emissions than standard hybrids and, in most cases, fewer overall emissions as well.

Because people generally commute only about 33 miles a day, plug-ins could become a viable form of transportation, the study posits. Thus, they could drive to work, come home and charge up the car. New power plants wouldn't be needed for charging these cars because electricity is fairly abundant at night. (Brownouts occur in the afternoon because large groups of people tap into the grid to turn on their air conditioners, which stresses the capacity of existing power plants.) Charging at night during the off-peak hours costs less because demand is far lower.

"We were very conservative in looking at the idle capacity of power generation assets," PNNL scientist Michael Kintner-Meyer said in a statement. "The estimates didn't include hydro, renewables or nuclear plants. It also didn't include plants designed to meet peak demand because they don't operate continuously. We still found that across the country, 84 percent of the additional electricity demand created by plug-ins could be met by idle generation capacity."

Some have also said that plug-ins and electric cars could be recharged with solar panels installed in parking garages. Altair Nanotechnologies, meanwhile, said it has developed batteries that can get recharged in a matter of minutes on a special charger.

The study also said plug-ins could have benefits for national security. Roughly 73 percent of oil imported to the U.S. goes into cars.

Despite the benefits, plug-ins aren't cheap. Converting a regular hybrid to a plug-in costs around $10,000, according to plug-in advocates.