The high cost of batteries is one of the biggest reasons why electric vehicles aren't widespread. We recently wrote about an interesting solution to this problem--rather than equipping an electric vehicle with enough batteries for a day's driving, use a minimal amount of energy storage but provide a way to recharge quickly. This way you can spend a lot less on energy storage and bring the cost down to something competitive with conventional vehicles. In the case we wrote about, Sinautec Automobile Technologies has equipped buses with ultracapacitors with a very limited range--just a few miles--but that can be recharged in 30 seconds or so at bus stops.
Here's another approach from Proterra, a company based in Colorado. Instead of ultracapacitors, the company uses batteries from Altairnano that can recharge in 5 to 10 minutes at a special overhead recharging station. The solution doesn't seem as elegant as using fast-charging ultracapacitors--presumably you'd want a larger range between charges, so you'd need more batteries. But it might be good for some situations where you need a bus to travel further than a few miles between charges.
