What are some alternate sources of energy for cars?

What are some alternate sources of energy for cars?
Modern, fuel injected, gasoline powered cars can be converted to run on propane gas or natural gas. They can also be converted to run Ethanol 85 (grain alcohol made from corn, sugar, grass, or wood, blended with gasoline on an 85% ethanol to 15% gasoline ratio). Older diesel powered engines can be run on common kitchen grease and newer ones can be run on a 20% grease to 80% diesel fuel mix (called B20 biodiesel).

Most manufactures are producing Hybrid Electric Vehicles, which usually have a gasoline engine that is used to recharge the battery, used by the electric motors that drive the car. Some use the engine to help the motors under hard acceleration and it is otherwise unused. Others rely solely on the gasoline engine for movement and use the electric motor as an extra power boost, so a smaller, less powerful engine could be used.

Many companies are coming out with Battery Electric Vehicles (BEV's), which rely on reachable batteries to power the dive motors and vehicle accessories. BEV's have most commonly been limited to slow, small vehicles, like golf carts because of limits in battery technology. The California based auto manufacture, Tesla, has been producing high end BEV sports cars since 2003, and manufacturers like Chevrolet and Ford have plans for affordable BEV family sedans for the 2010 model year.

The future of the Battery Electric Vehicle is the Hydrogen Fuel Cell Vehicle. The hydrogen fuel cell uses a complex electrochemical process to remove the free electrons from hydrogen gas to recharge batteries for the electric motors. The only emissions are water and heat and current prototypes have proven more efficient than and as safe as gasoline powered vehicles. General Motors has a working prototype of a Hydrogen Fuel Cell Vehicle and has plans for releasing it for the 2020 model year.