Three of the biggest energy consumers -- the transportation, utilities and building sectors -- are banding together to green business.

In the past, energy efficiency has been addressed largely on a sector-by-sector basis. Not anymore. A number of companies and organizations, including auto manufacturers and power companies, are coming together to pave the way toward widespread adoption of plug-in hybrid vehicles, leading to energy savings on all fronts, experts say.

Electric and hybrid vehicles present an increasingly promising alternative to conventional cars and trucks, which guzzle 40 percent of total U.S. oil consumption, according to the U.S. Energy Information Administration. Plug-in cars run off electrically charged batteries and, in the case of hybrids, also can use regular gasoline for fuel once they travel beyond the battery range, about 40 miles.

A number of auto manufacturers plan to release hybrid vehicles in the next couple of years, including Chevrolet, Toyota and Nissan.

Although electric cars cut oil consumption, leading to national security gains, they don't necessarily benefit the environment as they're only as clean as the electricity they rely on. While auto manufacturers have been developing electric cars, utility companies simultaneously have been trying to optimize renewable energy sources to produce electricity -- a difficult undertaking because wind and solar are intermittent, producing large surpluses of energy and then none at all.

Unfortunately, the whims of Mother Nature rarely reflect those of energy users. It's expensive to store excess energy, so electricity from sustainable sources often gets wasted during peak production and supplemented with carbon-based power during peak usage periods.

A new technology called "smart charging" will solve this dilemma by syncing up electric cars with renewable energy production, said David Kaplan, head of the electric vehicle management business for GridPoint, a company that works on grid technologies.

"Smart charging basically allows you to time the charging (of a car) to happen when, for example, there's a lot of wind energy coming into the grid," Kaplan told United Press International.

Under this system, drivers would plug their cars in at night, but the batteries wouldn't necessarily begin charging right away. Instead, the grid and the car would be able to communicate with each other, allowing the car to charge whenever excess renewable energy became available. This would prevent waste, Kaplan said, particularly as an increase in wind power generation is projected to coincide with the release of several electric vehicle models in the next couple of years, including new cars from Chevrolet, Toyota and Nissan.

"Wind blows most intensely at night, and there's no way to use all that wind power today," he said. "We can match up that clean power with a perfect resource."

This also would prevent a power overload if thousands or millions of drivers simultaneously plugged their cars in after returning home in the evening -- a peak time for energy usage already.

Eventually, consumers might even be able to sell back any leftover energy in their car batteries or use it to power their homes when they're done driving for the day.

Even before that happens, consumers would still save a lot of money by charging during off-peak times, said Andrew Tang, senior director of the smart energy web at Pacific Gas and Electric, a California-based utility.

"You're looking at 3 to 5 cents per mile to operate an electric vehicle vs. 15 to 20 cents per mile to operate a (conventional) vehicle that gets 20 to 25 miles per gallon," Tang said.

Smart charging gives consumers much more control over where their electricity comes from and allows communication between different players -- like cars and utilities -- in much the same way that the Internet networks information.

In order to do this, though, the system has to be standardized, said Dave Bieselin, director of software development at Cisco Systems, which provides Internet-based networking services.

"This will allow you to move all around the country -- and, hopefully, the world -- with your car," Bieselin said.

Another of the chief obstacles impeding the adoption of plug-in fleets is a lack of infrastructure, such as charge stations to power batteries. As a result, the business opportunities for the building sector are enormous, said Michael Brylawski of the Rocky Mountain Institute, a non-profit think tank that recently brought together auto manufacturers, utility companies, non-profit organizations and others to discuss "smart garage" implementation.

"We see the opportunity for new green infrastructure," he said. "It will include significant U.S. investment in charge stations -- depending on the scenario, tens of thousands to hundreds of millions."

Major developers and retailers, such as Starbucks or Wal-Mart, could draw in consumers by installing charge stations, allowing customers to refuel while shopping.

Other drivers will want more than just a quick power-up. Currently, there are only 54 million garages in the United States, meaning another 193 million drivers, if they go electric, will need charging stations outside their homes. Parking garages or curbside plug-in locations could provide electricity for these cars.

Despite all the benefits, consumers will have to play a big role if electric vehicles are to replace the conventional car and truck fleet, said Laura Schewel, manager of RMI's Smart Garage project. The best way to ensure consumer demand is to create an electric-friendly environment, she said.

"A city can make itself an ecosystem that welcomes electric vehicles," she said, pointing to Portland, Ore.; San Jose, Calif.; and Boulder, Colo., as examples of quick movers in this area.

The other important aspect of rolling out the smart system is marketing, said Bieselin from Cisco.

"We need to make sure consumers know, and the world knows, that green does not equal hardship," he said.