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For MIRAI—For the Future

What Is an FCV—the Ultimate Eco-Car?

A fuel cell vehicle (FCV) uses hydrogen for fuel, and emits only water as exhaust—precisely the reason that they are being lauded as the "ultimate eco-car."

Now in this era of concern for the global environment, exhaust emissions from vehicles are being blamed for causing it damage—in order to stop the global warming caused by this damage, ZEV regulations*1 as well as other regulations have been enacted around the world. In response to these, automobile manufacturers have started work on electric vehicles (EV), hybrid vehicles (HV), plug-in hybrid vehicles (PHV), and other solutions more considerate of the environment.

Within Japan, Toyota Motor Corporation started work on FCVs in 1992. At the end of 2002, Toyota released the world's first SUV type FCV—the Toyota FCHV, which was limited to the Japan and United States markets. This was the first to receive type approval in Japan in 2005, and in 2008 the improved version "Toyota FCHV-adv" was released. Next was the much-hyped MIRAI for general consumer use, released at the end of 2014.

Eco Car

FCVs are called the ultimate eco-car—but how do they work?

An FCV incorporates a fuel cell, in which a chemical reaction between hydrogen and oxygen generates electricity, which is used to drive motors. Maybe you remember learning about the electrolysis of water in school? H2O is the symbol for water, and this experiment applies electricity to the water, separating it into its two chemical components—hydrogen (H) and oxygen (O).

What happens in a fuel cell is the reverse of this reaction. Hydrogen from an external source is stored in a tank, and this is combined with oxygen from the atmosphere in a chemical reaction, a process which also generates electricity. The only emissions from this chemical reaction are water.

So, what role does this oxygen-supplying air compressor (air compressor) play in an FCV? As we've already mentioned, the fuel cell in an FCV passes hydrogen and oxygen through a chemical reaction, but to do this, it needs to take in and compress air containing oxygen from the atmosphere, and feed this to the fuel cell.

This is the role of the air compressor. (The hydrogen circulation pump circulates a portion of the hydrogen that did not undergo a chemical reaction, feeding this back into the fuel cell.)

The air compressor is a vital component, given that it must constantly provide oxygen if the FCV is to generate electricity. The speed and fuel economy of the FCV is directly dependent upon how well this part performs.


*1: ZEV regulations
An abbreviation of Zero Emission Vehicle, which refers to EVs and FCVs that emit no exhaust gases. The world's toughest ZEV regulations are considered to be in California, and manufacturers who sell more than 60,000 vehicles within the state are required to have a set proportion of their vehicles comprising ZEV.