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Electrolysis of Water and how Hydrogen Fuel Cells work



Chemical reactions are utilised in a wide variety of technologies and day to day activities. Electrolysis of water involves the decomposition of water into hydrogen gas and oxygen gas.

2 H2O(l) 2 H2(g) + O2(g)

This is done using electrodes (cathodes and anodes) which splits the water molecules using the positively and negatively charged properties of the hydrogen and oxygen. Electrolysis of pure water is very slow, pure water has an electrical conductivity about one millionth that of seawater. However the electrolysis process can be speed up with the addition of a salt, acid or base.

The most common way for energy to be released and utilised in a hydrogen fuel cell, is through the combustion of hydrogen molecules in the presence of oxygen.

2 H2(g) + O2(g) 2 H2O(l)

This is achieved by several processes;
• Proton Exchange Membrane (PEM) Fuel Cells
• Solid Oxide Fuel Cells
• Alkaline Fuel Cells
• Regenerative Fuel Cells
The basics of each process are fundamentally the same, the electrons of hydrogen are channelled through an electrical circuit powering an object, hydrogen is then reacted with oxygen to create water molecules.

A PEM Fuel Cell is the most available hydrogen fuel cell to use. A PEM Fuel Cell consists of four main parts;
1. Anode: the negative post which conducts freed hydrogen electrons to the circuit.
2. Cathode: the positive post conducting electrons to the catalyst.
3. Catalyst: a special material designed to create a reaction between the reactants, hydrogen and oxygen.
4. Electrolyte: is a proton exchange membrane conducting positive ions while blocking electrons.
The process begins when hydrogen gas (H2) is delivered to the anode, a catalyst separates the hydrogen proton from the electron, the now...