Global warming, dependence on foreign oil, and the high price of gasoline have people thinking about alternative fuels for the cars of the future. While there are many potential new fuels out there, one of the most researched -- and most promising -- is simple electricity.

Automakers have already started experimenting with electric vehicles. Electric vehicles have three basic parts: the batteries, which are the power source for the car; the motor, which converts the power into useable energy that can turn the wheels; and the controller, which works like a big dimmer switch to regulate the electricity.

To refuel an electric vehicle (EV), all you need is an electrical outlet. Any standard household outlet will do, but an outlet with higher voltage will do the job faster. Some cities, like Portland, Ore., are installing curbside charging units so that current and future EVs will be able to top off their batteries themselves while their owners work or run errands.

­The EVs available today can't yet replace all the gasoline-powered cars and trucks on the road. EV speeds are usually low, about 35 miles per hour (56 kilometers per hour). Most EVs can travel about 40 miles (64 kilometers) per charge, which is roughly the same distance as the average daily American comm­ute. The cars can charge overnight at a regular outlet or in a few hours at a higher-voltage outlet. They also have zero emissions.

Most of the advances being made in EVs are in battery technology and design. Lead-acid batteries were used for decades -- even in the early 1990s, when EVs first became popular. However, lead-acid batteries don't get people as far as we'd like, or as quickly. Read on to find out where and how labs are working to improve EVs for modern consumers.