Hydrogen + Oxygen (from the air) → Electricity + Water Vapor
A fuel cell is a device that converts chemical energy into electrical energy.
A PEM (Proton Exchange Membrane) cell uses hydrogen gas and oxygen (from the air) as fuel. The product of the reaction in the cell is water releasing electricity, and heat.
This is a much cleaner way to produce energy than burning coal or internal combustion engines which produce poisonous bi-products.
Since oxygen is readily available in the atmosphere we only need to supply the fuel cell with hydrogen which can be made by electrolysis
The main parts of a PEM Fuel Cell:
At the anode the platinum catalyst cause the hydrogen atom to lose its electron and turn into a hydrogen ion (H+). The channels in the anode spread the hydrogen gas equally over the surface..
At the cathode electrons combine with the hydrogen ions to form hydrogen which join with oxygen atoms to form water.
The key to the cell is the Polymer Electrolyte Membane (PEM) which allows the hydrogen ions to pass though it but blocks the electrons.
The electrons have to move along an external wire (as in a normal battery cell) to get from the anode to the cathode.
The catalyst is a special material that speeds up the reaction between oxygen and hydrogen. It is usually made of tiny platinum particles very thinly coated onto carbon paper or cloth. The catalyst is rough and porous so that the maximum surface area of the platinum can be exposed to the hydrogen or oxygen. The platinum-coated side of the catalyst faces the PEM.
Due to the high energetic content of hydrogen and high efficiency of fuel cells (55%), this great technology can be used in many applications like transport (cars, buses, forklifts, etc) and backup power to produce electricity during a failure of the electricity grid.
Advantages fuel cells over internal combustion engines:
- Fuel cells are a lot more efficient than internal combustion engines as they have no moving parts and do not produce so much wasted heat energy
- The waste product of the cell is just water and a little heat. Internal combustion engines cause a lot of pollution
- Fuel cells have no moving parts. They are thus much more reliable than traditional engines.
- Hydrogen can be produced easily and cleanly whereas oil production and refining can be damaging to the environment.