Electricity generation explained

Although static electricity is present in nature, in thunderclouds, nerve endings, and brains, there is no way at present to harness this in such a way that it could provide a steady flow of electricity to power appliances.

Though electricity is a far more versatile form of energy, it cannot be tapped directly from nature, and has to be generated using the energy created from a primary energy source, such as burning coal or splitting uranium atoms. For this reason, it is referred to as being a secondary source of energy.

A couple of hundred years ago, the energy needs of the average household were met by primary energy devices such as kerosene lamps, coal fires, and cold stores.

Nowadays, electricity is so much a part of our daily life that we rarely think about what life would be like without it, except in the rare instance of a power cut. The reason for its ubiquity is that it is by far the most versatile and convenient energy source available, and can be used to power virtually any type of appliance, from a computer to a refrigerator.

The principle behind the modern electric generator is still the same as that pioneered by Michael Faraday in the 1830s, when he discovered that turning a magnet inside a coil of wire induced a current in the wire.

It was not until the far more powerful electromagnet came on the scene later in the 19th century that large scale electrical generation based upon this principle could become a workable reality.

The generators used in modern power stations utilise a huge electromagnet rotating inside a series of insulated coils, inducing a current in each one, which is then summed into a far larger current when those coils are joined at the end of the circuit.

These giant electromagnets are not going to rotate themselves, however, and require the energy for movement to come from a secondary source such as a steam turbine or a windmill. Typically, a power plant can achieve an energy efficiency of around 35%, meaning that only just over a third of the energy used to create the electricity is actually turned into electrical energy.

The majority of power stations use turbines, which are essentially large water wheels that are propelled by jets of steam produced by heating water with coal, gas, petrol, or nuclear power.