Different Types of Eco-Car

Let's take a look at the characteristics of the different types of eco-cars.

Natural gas cars Cars that run on natural gas emit 25% less carbon dioxide than gasoline-powered ones and close to zero harmful substances. They have less power than gasoline cars, though, and the fuel tank is bulky.

Electric cars Electric cars rely on a battery that is charged between uses. Because they burn no fuel, they emit nothing at all. When they were first produced, the distance they could travel on a single charge was quite short, but this has improved recently, and they are becoming more practical. One problem with electric cars, though, is that the battery is expensive, making the car itself expensive. In Japan at present, these cars are used mostly by companies and government offices. There are also car-sharing experiments in which people in the same neighborhood use the same electric car.

Hybrid cars Most hybrid vehicles make use of an efficient combination of a gasoline engine and an electric motor. For example, when the car comes to a stop at a red light, the engine is automatically switched off in order to prevent harmful emissions. When the car begins to move after the light turns green, it relies on the motor while the engine gets started again. The electric motor reduces the burden on the engine when the car accelerates, enabling the car to emit less nitrogen oxide. Japan has been a world leader in hybrid technology, and the nation exports a large number of these vehicles. The Toyota Prius and Estima Hybrid and the Honda Civic are available as hybrid models.

Fuel-cell cars The fuel-cell car, which has been called the ultimate eco-car, is still in the development stage. This type of car works by chemically combining hydrogen fuel with oxygen from the air to produce electricity. The only byproduct emitted by a fuel-cell car is a small amount of water.

Hydrogen explodes rather easily, however, and it would be quite dangerous for a car loaded with it to get into a traffic accident. In addition, the tank needed to hold the hydrogen is very bulky. These factors have led some people to the conclusion that it is more realistic to use methods that extract hydrogen from other fuels, such as natural gas or methanol. By using these sorts of fuels, the amount of harmful substances that are emitted will be much less than what is produced by a gasoline-burning vehicle.

In the United States a method of creating electricity using hydrogen extracted from gasoline is being studied. While some harmful substances will still be emitted and petroleum will still be needed, this method is advantageous in that existing gas stations can be used to supply the fuel. Japan's Toyota Motor Corp. and America's General Motors and Exxon Mobil have made clear that they intend to work together to develop a fuel-cell vehicle that uses this method.

Photos: Toyota Motor Corp. (top, second, third, and fourth); Honda Motor Co. (bottom)