Fuel Cell Vehicles

Auto manufacturers, both here and abroad are scrambling to produce electric vehicles. The most successful out of the gun has been the high end Tesla model S. Others include the Nissan Leaf and BMW i3. Chevrolet will be introducing the Bolt in the near future. All these cars are whisper quite and perform well. They all however suffer the drawback of limited range on a charge and a rather long recharge time at least compared to the time to fill a tank of gasoline.

Notably missing from the cars listed above is the world’s largest car manufacturer – Toyota. They set the standard for hybrid cars with the introduction of the Prius in 2001. It is powered by a internal combustion engine (ICE) which is supported by a electric motor and battery that results in quite high mileage compared to other ICE powered cars.

Although Toyota has yet to produce an all-electric car, they seem to be hedging their bet on the development of an alternative to electric cars with batteries. In development is an electric car that runs off of a fuel cell that is powered by Hydrogen. The chemistry of the fuel cell is just the opposite of the high school CHEM class experiment called electrolysis. If you pass an electric current through water it cause the production of Hydrogen and Oxygen from the water. This process consumes electrical energy.

In a fuel cell powered vehicle, hydrogen gas is stored at high pressure in a tank. When electrical energy is needed, the gas is passed into the fuel cell where it combines with oxygen from the air to produce electrical energy. The principle is simple but in practice fuel cells are complex devices that require unique and often expensive catalysts to make the chemical reaction proceed at a sufficient rate to power a vehicle. The real advantage to this technology is the range of the vehicle between refills. It should be possible to store enough Hydrogen in a vehicle to get a lot more range than can be achieved with charging batteries.

A problem with the use of Hydrogen is one of thermodynamics. It takes more energy to produce Hydrogen than you can get back when used. Basically any time you do work, energy will be wasted. Thermodynamically work is the use of energy to drive a process, be it chemical , electrical or mechanical. In the case of Hydrogen energy losses occur when it is created from water by electrolysis, when it is compressed for transportation, when it is decompressed for use, and when it is used in a fuel cell. Each of these processes constitute an inefficiency where energy is lost.

Another problem is that Hydrogen is a gas and somewhat difficult to handle. Hydrogen stored in metal containers, or piped in metal pipes causes embrittlement. The metals become more fragile and likely to fail under pressure on exposure to Hydrogen. It is also problematic in that it has a low energy density by volume. It takes a lot of space to store a given weight of Hydrogen.

Toyota is betting that these difficulties with the production, storage and utilization of Hydrogen can be overcome.

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