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Generation...
Coal, uranium, oil, gas, hydro, wind and solar are the main sources of energy used in the generation of electricity. Much of the electricity is produced in thermal power stations which comprise:-
Boiler
Heat produced by burning fuel is used to convert water (circulating in tubes) into steam. The steam, at a very high temperature and pressure, is then directed onto the turbine.
Turbine
The turbine is a rotating shaft to which is attached a series of blades. As the high pressure steam passes through the turbine, the blades are forced to turn at high speed, rotating the shaft - similar to the action of a windmill.
From the turbine the steam enters a condenser, passing over tubes containing cool water. This cools the steam which condenses back into water and also creates a vacuum to help improve the flow of steam through the turbine. A series of pumps then return the water under pressure to the boiler to be recirculated in the boiler tubes.
Generator
Attached to the turbine shaft is the generator which is basically a powerful electro-magnet surrounded by a series of windings - the modern day equivalent of Faraday’s bar magnet and coil of wire. The rotation of the turbine causes the windings to be cut by the magnetic field of the electromagnet and thus electricity is generated in the windings.
Renewables
A small proportion of electricity is already generated from renewable sources, but this is expected to grow significantly in the next few years. As and example, the UK Government is targeting a 34% reduction in carbon emissions by 2020, and 80% by 2050. There are alternative solutions to this problem, but a substantial increase in renewable sources such as wind, wave and solar generation is likely.
Transmission...
Generator Transformer
Electricity is usually generated in power stations at about 22,000 volts, then increased by substation transformers to 275,000 and 400,000 volts, and fed into the National Grid system to be transmitted, efficiently, over long distances. The reason we do this is to reduce the amount of energy lost in the conductors as it is transported. Raising the voltage reduces the electric current flowing and it is current that causes heat losses.
National Grid
National Grid circuits are the motorways of electricity systems. A network of overhead lines, underground conductors and substations link the power stations and allow large amounts of electricity to be transmitted around the country to meet the demand at any time.
Substations
Substations control the voltage and direction of electricity. Transformers are used to increase the voltage of electricity into the National Grid system for transmission, and to reduce the voltage to lower levels for distribution by the networks of the local electricity companies.
Increasingly, governments are investing in new technologies that will enable us to transport electricity more efficiently. They are also investing in additional connections to other Asian countries and in the networks needed to connect in new, renewable sources of electricity.
Distribution...
Supply to Areas
Electricity is taken from the National Grid transmission system and reduced to 132,000 volts and lower voltages for distribution by the local electricity companies. Some large industrial customers requiring large amounts of electricity may be supplied direct from substations at 33,000 volts.
Supply to Towns
The supply is further reduced to 11,000 volts for distribution to towns, villages and direct to small industrial customers.
Supply to the Home
The voltage is finally reduced by transformers to 230 volts for use in homes, schools, shops and businesses.
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