National labs examining impact of plug-in hybrids

If plug-in hybrid cars become popular, the cars could potentially reduce greenhouse gas emissions and dependence on foreign oil. But will they cause electricity prices to zoom?

Scientists at the Pacific Northwest National Labs are trying to figure out that right now, according to staff scientist Michael Kintner-Meyer in an interview. PNNL hopes to issue a report this summer that will help answer that question.

Last year, PNNL studied how well the grid, as it exists today, could accommodate an influx of plug-in hybrids. (Unlike a conventional Prius hybrid, plug-ins can be charged from a wall socket. General Motors, Toyota Motor, Fisker Automotive, and others plan to come out with plug-ins in the 2009 to 2010 time frame. For those who can't wait, some small outfits will retrofit your Prius.)

The lab estimated that 73 percent of the cars, pickup trucks, SUVs, and vans in the U.S. could be exchanged for plug-ins, and the grid could handle it. If you eliminate vans, the figure jumps to 84 percent. The estimate, however, assumes that the cars would largely be charged at night, when electrical demand is low but power plants continue to produce electricity.

"The valleys (of electrical demand at night) are sufficiently deep," he said.

If such a conversion could occur, it could reduce U.S. oil consumption by about 6.5 million barrels of oil a day. The U.S. consumes about 21 million barrels a day, according to the Department of Energy. You could also run the entire electrical grid for seven minutes on all of those plug-in batteries, he added.

But pulling such a conversion off would increase demand for electricity. If the 73 percent target were hit, it would increase demand by 910 billion kilowatt hours, or boost demand by 24 percent from the 2002 demand figures, he noted. It's an open question whether the grid could handle this on a sustained basis. Planned outages would likely become more common. Utilities would also have to accelerate investments in smart grid technologies that balance loads. Investment in the grid has slowed since the mid-'90s, he said.

This could set off price fluctuations with natural gas or even coal. The emissions benefits would also vary by geography. Ohio uses more coal per capita than California, so emissions from coal there could grow as tailpipe emissions go down.

The initial study also assumed that people would charge during off-peak hours, and there's no guarantee in reality that they will. (A lot of plug-in companies talk about charging the cars at work).

Both the DOE and several auto companies, he added, are trying to bring down the cost of plug-ins. Now, converting a Prius to a plug-in runs about $15,000, according to conversion specialists I've talked to. The DOE has set a target of bringing down the premium of a from-the-factory plug-in to the $3,000 to $6,000 level by 2014.