Electric cars overtake fossil fuel cars in numbers, worldwide

Battery technology

The future of battery electric vehicles depends primarily upon the cost and availability of batteries with high energy densities, power density, short charge time and long life, as all other aspects such as motors, motor controllers, and chargers are fairly mature and cost-competitive with internal combustion engine components. Li-ion, Li-poly and zinc-air batteries have demonstrated energy densities high enough to deliver range and recharge times comparable to conventional vehicles.[citation needed]By the year 2020, an estimated 30% of the cars driving on the road will be battery, electric or plug-in hybrid.[52]

Bolloré, a French logistics conglomerate, developed a concept car, called the Bluecar, using Lithium-ion polymer batteries developed by a subsidiary, Batscap. It had a range of 250 km (160 mi) and top speed of 125 km/h (80 mph).[53]
The cathodes of early 2007 lithium-ion batteries are made from lithium-cobalt metal oxide. That material is expensive, and can release oxygen if its cell is overcharged. If the cobalt is replaced with iron phosphates, the cells will not burn or release oxygen under any charge. The price premium for early 2007 hybrids is about $5000 US, some $3000 of which is for their NiMH battery packs. At early 2007 gasoline and electricity prices, that would break even after six to ten years of operation. The hybrid premium could fall to $2000 in five years, with $1200 or more of that being cost of lithium-ion batteries, breaking even after three years.[54]

[edit] Other methods of energy storage
Experimental supercapacitors and flywheel energy storage devices offer comparable storage capacity, faster charging, and lower volatility. They have the potential to overtake batteries as the preferred rechargeable storage for EVs.[55] The FIA included their use in its sporting regulations of energy systems for Formula One race vehicles in 2007 (for supercapacitors) and 2009 (for flywheel energy storage devices).
EEStor claims to have developed a supercapacitor for electricity storage. These units are titanate coated with aluminum oxide and glass to achieve a level of capacitance claimed to be much higher than that currently available on the market. The claimed energy density is 1.0 MJ/kg whereas existing commercial supercapacitors typically have an energy density of around 0.01 MJ/kg, while lithium-ion batteries have an energy density of around 0.59 MJ/kg to 0.95 MJ/kg). EEStor claims that a 5 minute charge should give the supercapacitor enough energy to give a car a range of 400 km (250 mi).[56]

[edit] Solar cars

Solar cars are electric cars that derive most or all of their electricity from built in solar panels. After the 2005 World Solar Challenge established that solar race cars could exceed highway speeds, the specifications were changed to provide for vehicles that with little modification could be used for transportation.
http://en.wikipedia.org/wiki/Electric_car