What is a hydrogen fuel cell?
Hydrogen fuel cell is a device which converts the chemical energy, that is the energy stored in the chemical bonds of hydrogen molecule H2 and oxygen molecule O2, into electrical energy. It also produces heat and water H2O as byproducts, and no harmful chemicals or pollutants are produced in this process.
Like normal cells, hydrogen fuel cells also produce electrical energy from chemical energy. But normal cells can only be used for limited periods of time owing to the limited stock of chemicals contained in them, and they also require longer durations of time for recharging.
Hydrogen fuel cells, on the other hand, can be used countinuously for as long as hydrogen and oxygen are supplied into them. The time taken to recharge a hydrogen fuel cell is the time required to fill the hydrogen tank of the fuel cell, and it is quite small compared to the recharging time of normal cells which are charged by electricity.
Hydrogen fuel cells are more efficient than normal rechargeable cells or batteries and also more efficient than hydrogen internal combustion engines.
How a hydrogen fuel cell works?
A hydrogen fuel cell consists of a catalysed anode (negative electrode), a catalysed cathode (positive electrode), and an electrolyte.
Hydrogen H2 molecules get ionized at the anode into H+ ions and electrons. H+ ions pass into the electrolyte and move toward the cathode. The electrons move from the anode to the cathode via an external circuit. These moving electrons provide electrical energy to run an electric device such as an electric bulb or the motor of a hydrogen fuel cell car.
At the cathode the electrons ionize the oxygen molecules into O2- ions. H+ ions coming from the anode and O2- ions combine together to form water H2O which is a byproduct of this process.
A single fuel cell produces small amounts of voltage and current. Many fuel cells are usually stacked together in practical applications to produce the required amounts of voltage and current.
Hydrogen fuel cells can be of many types depending on the materials used in electrodes, catalysts, and electrolytes. However, their working principles remain the same.