from C|NET News.com

SUNNYVALE, Calif.--Plug-in hybrids could one day turn motorists into energy traders, according to Pacific Gas & Electric.

The utility demonstrated on Monday a twist on the concept of the plug-in hybrid, which uses a higher capacity battery than ordinary hybrids like Toyota's Prius. The idea? To let car owners sell electricity purchased overnight back to the grid for a modest profit or to power their homes in the event of an emergency with the Vehicle-to-Grid program, said Bob Howard, a vice president with PG&E.

The demonstration came during the Alternative Energy Solutions Summit, sponsored by the Silicon Valley Leadership Group and hosted by Advanced Micro Devices at its headquarters here. Public officials from Silicon Valley communities and organizations gathered to hear discussions about how the region can invest and profit from demand for cleaner and more efficient sources of power.

U.S. Senator Barbara Boxer of California discussed some of the efforts she is taking as the new chairman of the Senate Committee on Environment and Public Works to get the U.S. government more focused on energy efficiency and alternative sources of power.

"Global warming is the challenge of our generation," she said. "I hope to make this one of the biggest issues in the (2008) presidential race, where the nominees are arguing over who has the better plan to meet this challenge."

Utilities aren't historically known for their environmentally friendly practices, Howard noted, as they produce about 40 percent of all greenhouse gases in the U.S. "But if there has ever been a place to start and gather the interest of customers, California and the (San Francisco) Bay Area is the place."

Hybrids like the Prius have been hot sellers in the Bay Area, and the plug-in hybrid goes a step further. For $10,000, hybrid owners can have a large battery capable of storing 9 kilowatt/hours of electricity installed in their rear cargo area. The car works the same way as a regular hybrid, drawing on the battery at low speeds, but the extra battery can allow the car to get up to 100 miles per gallon of gas, said Felix Kramer, founder of CalCars.

It's easy to see the benefit to the driver and environment, but utility companies could also get a boost from plug-in hybrids, Howard said. The particulars are still being worked out, but PG&E demonstrated how a plug-in hybrid could be connected to a home's electrical system or some other type of collection point at mass-transit hubs or office parking lots and send power back to the charging station--or just through a wall outlet--from the car.

Electricity is cheaper during off-peak consumption hours like the middle of the night, and utilities are also able to use renewable sources of energy during those periods, Howard said. Owners could purchase electricity cheaply at night, store it in their plug-in hybrids, and sell it back to the utility at higher rates during the day--when demand is much higher for electrical power.

There's still a lot of research that needs to be done in this area, but PG&E is studying how to incorporate the technology into its own service vehicles, Howard said. Challenges include figuring out how and where to build collection points, and making it as easy to remove power from a battery as it is to charge the battery.