Two major utility companies plan to switch their cars and trucks to plug-in hybrid or all-electric vehicles.

FPL Group Inc. (NYSE:FPL), based in Juno, Fla., and Duke Energy (NYSE:DUK), headquartered in Charlotte, N.C., are working together starting January 1 to have 100% of all their new fleet vehicles be electric-powered by December 31, 2020.

The joint commitment represents more than 10,000 vehicles and potential revenues of at least $600 million for manufacturers who can produce viable plug-in electric vehicles, the firms say. The conversion has the potential to reduce greenhouse gas emissions by more than 125,000 metric tons over 10 years.

Plug-in electric vehicles (PEVs) reduce overall carbon emissions by up to 70% (100% if charged by zero-carbon, renewable energy sources) and lower fuel costs by about 80%. If plug-in electric vehicles replaced all gasoline-powered vehicles in the United States, they would reduce the need for foreign oil imports by nearly two-thirds.

Starting in January, both companies will begin tracking their progress toward the goal. While passenger vehicles and smaller trucks are already planned, Duke Energy and FPL Group will work closely with manufacturers to test and measure the effectiveness of prototype bucket trucks in 2011 and 2012. After that, the firms will transition vehicles, educate the public, solicit additional partners and provide periodic progress updates.

"A 10-year commitment gives us time to adopt, test and integrate new technology into fleets as a wider range of vehicles are developed," said Jim Rogers, chairman, president and CEO of Duke Energy. "Currently, the only near-term options for available PEV supply are sedans, minivans, vans and a few bucket trucks. Over a 10-year horizon, it is expected that options will be available for most utility service categories."