The linchpin to the development of electric vehicles still comes down to developing the right battery.
Many of the major automakers have gravitated toward lithium ion -- the type of battery used in smaller devices such as notebook computers and digital media players. It is lighter, holds a stronger charge and has the potential to last longer.

But safety and cost issues remain. Critics, meanwhile, remain skeptical about the battery's environmentally friendly credentials, especially the concept and practicality of "zero emissions." Still, major players predict 2010 will be a turning point for clean electric and next-generation hybrid cars as the new battery comes on the market.