What makes Fuel Cell Stacks work?

Fuel cells need a continuous feed of air and hydrogen to produce current. During operation the fuel cell (stack) produces heat which has to be removed. Therefore, a stack needs ancillary components to operate. These components are:

• a compressor or blower to provide air for the cathode,
• a cooling circuit,
• a water separator to remove product water from the cathode exit gases
• a controller system
• a fuel supply system
  

The fuel supply may be a simple cylinder containing compressed hydrogen and pressure controller. The use of liquid hydrogen or metal hydrides makes the system somewhat less simple, since heat must be provided to the tank. If instead of hydrogen a hydrocarbon is used as a fuel, the fuel supply system becomes more complicated. In this case a fuel processor (fuel reformer and gas purifier) is required to provide hydrogen for the fuel cells. The electrical energy produced by the fuel cell stack(s) can be fed to the motor invertor directly. In some cases, it may be attractive to use a buffer system, such as a battery, super capacitor or fly wheel. The buffer will supply peak power. This may be needed during start-up, or during acceleration. The buffer can also be used to absorb energy during regenerative braking. When a buffer is used, the system is referred to as a series hybrid system.