In reality it's simple economics (Score 1)

We've had the ability to get off petroleum for decades. During the 90s there was a push in California for electric cars. They didn't make it in the marketplace, most cite automobile manufacturers deliberately introducing flawed vehicles into the market. The company

http://www.electroauto.com/

sells and electric-car conversion kit. An inventor in korea has developed an electric generator from sea water

http://www.1000inventions.com/detail2.php?id=942

There are at least a dozen of these types of inventions out there. This is the only one I know of being looked at for commercial scale production. During the Y2K scare there was a small-scale commerically available version of this called the EnviroGen generator.

There is a company in India Reva producing a in-city car (tops out at 35 MPH). Most in-city trips top out at about 35 MPH. Plug this types of cars into a well designed mass-transit system such as DCs Metropolitan Transit bus/train system or Denver's Regional Transit bus/train system and you have a descent solution.

http://www.revaindia.com/

http://www.wmata.com/

http://www.rtd-denver.com/