How a Fuel Cell Works
A fuel cell generates electrical power by converting the chemical energy of a fuel into electrical energy by way of an electrochemical reaction without combustion. Fuel cells typically utilize hydrogen as the fuel and oxygen (from air) as the oxidant. The reaction results in electricity, by-product water and heat.
There are a number of fuel cell technologies, but we are focusing on proton exchange membrane (PEM) fuel cells. The basic cell consists of two electrodes, the anode and the cathode, separated by a polymer electrolyte membrane. Each of the electrodes is coated on one side with a platinum-based catalyst.
Hydrogen fuel is fed into the anode and air enters through the cathode. In the presence of the platinum catalyst, the hydrogen molecule splits into two protons and two electrons. The electrons from the hydrogen molecule flow through an external circuit creating an electrical current. Protons from the hydrogen are transported through the polymer electrolyte membrane and combine at the cathode with the electrons and oxygen from the air to form water and generate by-product heat.
Practical fuel cells comprise many cells connected in series to generate useful voltage and power levels.