As we wean cars and trucks off gasoline and other fossil fuels, battery technology will become increasingly important. Until recently, most larger-scale batteries were made using nickel and cadmium, but they were heavy, and lacked the long life needed to properly power cars. That's shifted in recent years to lithium-ion batteries, which can be made much smaller, with a superior weight-to-energy ratio. Your laptop, iPod and cell phone all use rechargeable lithium-ion batteries. The hope is that the same kind of technology will finally begin to make electric cars a reality, by producing batteries that can run a car for 40 miles or more per charge, but which won't take up the entire backseat. Tesla Motor's all-electric Roadster runs on nearly 7,000 lithium-ion cells, while General Motors's innovative plug-in car, the Volt, will be using 400-lb. lithium-ion batteries from the Korean company LG Chem. Right now lithium-ion batteries still aren't cheap enough to make electric cars truly economically viable, but the hope is that as projects like the Volt reach scale, the price will drop dramatically.
Here are the green energy ideas that can get us off fossil fuels and cool the climate