Greentech Media

"There are technology challenges and industry challenges, and they're a lot more complex than people believe," he said.

While scientists and entrepreneurs have been talking about the potential to use batteries to store energy for the grid, so that electricity could be collected during times of surplus and tapped into during times of high demand, it hasn't happened so far - in part, because of batteries' high cost.

A number of issues would need to be solved before plug-in vehicles could be used as backup power for the grid, including concerns about battery life, missing links in the monitoring and managing of electric charging and discharging and - not least of all - a lack of plug-in cars and sensor-equipped charging stations on the roads.

And will drivers be willing to pay thousands of dollars above the price of a hybrid without a guarantee that their cars will always recharge when they plug it in?

Reicher thinks so.

"I think people are going to respond well to having two power sources," he said, adding that they will get significant fuel-economy improvements.

Drivers wouldn't get stranded because they'd have between 10 to 15 gallons of gasoline in their tanks, he said. And the presumption is they would be able to charge up most of the time.

"It's going to be a rare instance that someone is going to be denied access to the grid, except in an emergency," he said. "It's more about where and at what time to charge."

While these vehicle-to-grid agreements are still years off, Reicher said the idea is you might make a deal with a utility to allow it to deplete a certain percent of your battery at a certain price. "It's not going to be a situation where the utility would have a free license to drain your battery," he said.

Still, Dikeman, who said he loves plug-in hybrids, said the potential benefits of storage are "way overstated" by plug-in proponents.

To make so-called vehicle-to-grid technologies worthwhile for drivers, the extra cost of plug-in hybrids must be made up by the difference between the electricity rates when demand is at its highest and when it's at its lowest, he said.

"That's not that big a difference," he said. "I don't think the business case is quite as high as people would like it to be."

He puts mainstream vehicle-to-grid use from plug-in hybrids some 40 to 50 years away. "We don't even have the cars yet," he said. "We don't even have a fleet of 1,000 cars right now."

Google's RechargeIt initiative is important because it gets pilot testing started, which is an essential step in bringing plug-in hybrids into the mainstream.

"If you can get mainstream plug-in cars out there, that would allow end users to switch from gasoline to wind or solar power," he said. "That's huge. Electricity could compete with gasoline for the first time."