How a fuel cell works

How a fuel cell works.

A fuel cell works more or less like an ordinary battery. Both systems generate electricity via an electrochemical process, and both contain two electrodes separated by an electrolyte. However, there is one important difference between them: the battery releases a previously determined amount of energy which is stored in it. In the fuel cell, on the other hand, the fuel (a gas) is fed continuously into the cell, which can thus supply energy as long as it has fuel. This usually consists of hydrogen, but natural gas (methane) can be utilized in certain types of high-temperature cells.

Oxygen or air is supplied to the cathode (see Figure), where it is converted to oxygen ions which migrate through the electrolyte to the anode, where they react with hydrogen. The outputs of the fuel cell are thus water, electrical energy and heat.

The cells can be connected up in a more or less infinite number of modules to produce whatever combination of current and voltage that is required. The normal voltage of a single fuel cell is about 1V.