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Electric power

Electric power, often known as power or electricity, involves the production and delivery of electrical energy in sufficient quantities to operate domestic appliances, office equipment, industrial machinery and provide sufficient energy for both domestic and commercial lighting, heating, cooking and industrial processes.


Although electricity had been known to be produced as a result of the chemical reactions that take place in an electrolytic cell since Alessandro Volta reported doing so in 1800, its production by this means was, and still is, expensive. In 1831, Michael Faraday devised a machine that generated electricity from rotary motion, however it took almost 50 years for the technology to reach a commercially viable stage. In 1878, Thomas Edison developed and sold a commercially viable replacement for gas lighting and heating using locally generated and distributed direct current electricity. In Edison's direct current system, generating stations needed to be close to or on the consumer's premises. To combat losses, and the voltage drops at end of the distribution, extra power generating stations needed to be installed. As Edison was not able to produce a system that permitted multiple generators to be connected together, expansion of his system required whole new generating stations to be constructed. The need for additional power plants is primarily explained by Ohm's law: as losses increase in proportion to the square of the current, or load, and in proportion to the resistance, having long cable runs in the Edison system meant using dangerous voltages in some places, or expensive and large cables or both.

Nikola Tesla, who had worked for Edison for a short time and appreciated the electrical theory in a way that Edison did not, devised an alternative system using alternating current. Tesla realised that while doubling the voltage would halve the current and reduce losses by three-quarters, only an alternating current system allowed the transformation between voltage levels in different parts of the system. He went on to develop the overall theory of his system, devising theoretical and practical alternatives for all of the direct current appliances then in use, and patented his novel ideas in 1887, in thirty separate patents.

In 1888, Tesla's work came to the attention of George Westinghouse, who owned a patent for a transformer and had been operating an alternating current lighting plant in Great Barrington, Massachusetts since 1886. While Westinghouse's system could use Edison's lights and had heaters, it did not have a motor. With Tesla and his patents, Westinghouse built a power system for a gold mine in Teluride in 1891, with a water driven 100 horsepower generator powering a 100 horsepower motor over a 2.5 mile (4 km) power line. Then, in a deal with General Electric, which Edison had been forced to sell, Westinghouse's company went on to construct a power station at the Niagara Falls, with three 5,000 horsepower Tesla generators supplying electricity to an aluminium smelter at Niagara and the town of Buffalo 22 mile (35 km) away. The Niagara power station commenced operation on April 20 1895. Its opening set the scene for the electric power industry for over a hundred years.

Electric Power Today

Today, Tesla's alternating-current electric power system is still the primary means of delivering electrical energy to consumers throughout the world. While high-voltage direct current (HVDC) is used to transmit large quantities of electricity over long distances, the bulk of electricity generation, transmission, distribution and supply takes place using alternating current.

In many countries, electric power companies own the whole infrastructure from generating stations to transmission and distribution infrastructure. For this reason, electric power is viewed as a natural monopoly. The industry is generally heavily regulated, often with price controls and is frequently government-owned and operated. In some countries, wholesale electricity markets operate, with generators and retailers trading electricity in a similar manner to shares and currency.

See also

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