Road traffic uses large amount of fossil fuel with associated CO2 emissions. Electric cars can increase efficiency and make the use of renewable energy sources such as wind energy possible.
The limited capacity and high cost of batteries limits the market for current electric vehicles.
Recently much activity has been started with the goal of supplying electric power to vehicles while moving in general traffic. This would allow the usage of smaller and cheaper batteries. Electrification is already common in Railroads. In road traffic trolley busses are an old technology.
The goal of current activities in the area is been to make systems that can be utilized by a wider range of diverse vehicles that can connect and disconnect from the system while moving at speed.
Such a system is often called an Electrical Road System, abbreviated ERS.
Such system has been ranked the number one emerging technology by the world economic forum 2013: http://forumblog.org/2013/02/top-10-emerging-technologies-for-2013/