Japanese energy giant Tokyo Electric Power Co. said Monday that it had begun testing power chargers at parking lots as part of efforts to bring commercially viable plug-in electric vehicles closer to reality.

TEPCO, the world's biggest private power supplier, has joined forces with parking lot operator Park24 Co. to build power plugs at eight parking lots in and around Tokyo.

The power company already has joint projects with Mitsubishi Motors and Subaru-brand maker Fuji Heavy Industries to develop plug-in electric vehicles.

For the experiment TEPCO will use its 40 Fuji Heavy-made vehicles and one Mitsubishi car, which are already used by its employees as company vehicles for short distance journeys.

The plug-in parking stations will be used to test charge electric vehicles while they are parked and to assess user friendliness and the impact on the performance of the vehicles, TEPCO said.

"We want to see whether the plug facilities at parking lots would significantly increase the driving distance of our vehicles," said a TEPCO spokesman.

Fuji Heavy's electric vehicle can run 10 to 15 kilometers (six to nine miles) on a one-hour charge.

The test will run until late March.

The dream of an electric car, which has been around since the time of Thomas Edison, has so far failed to break into the mainstream because of the high development cost and difficulties developing a suitable battery.

A number of Japanese automakers, led by Toyota, are developing plug-in electric cars as an alternatives to gasoline-powered cars amid record crude oil prices.

But some others including Honda Motor are more sceptical about the merits of plug-in electric vehicles.