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The electric power industry is the generation, transmission, distribution and sale of electric power to the general public. The electrical industry started with introduction of electric lighting in 1882. Throughout the 1880s and 1890s, growing economic and safety concerns lead to the regulation of the industry. Once an expensive novelty limited to the most densely populated areas, reliable and economical electric power has become a requirement for normal operation of all elements of developed economies. By the middle of the 20th century, electric power was seen as a "natural monopoly", only efficient if a restricted number of organizations participated in the market; in some areas, vertically-integrated companies provides all stages from generation to retail, and only governmental supervision regulated the rate of return and cost structure. Since the 1990s, many regions have opened up the generation and distribution of electric power to provide a more competitive electricity market. While such markets can be abusively manipulated with consequent adverse price and reliability impact to consumers, generally competitive production of electrical energy leads to worthwhile improvements in efficiency. However, transmission and distribution are harder problems since returns on investment are not as easy to find. The largest electric power companies in the world that deal with all aspects of production and sales of electric power are: ==History== 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 developed the voltaic pile 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, but it took almost 50 years for the technology to reach a commercially viable stage. In 1878, in the US, Thomas Edison developed and sold a commercially viable replacement for gas lighting and heating using locally generated and distributed direct current electricity. The world's first public electricity supply was provided in late 1881, when the streets of the Surrey town of Godalming in the UK were lit with electric light. This system was powered from a water wheel on the River Wey, which drove a Siemens alternator that supplied a number of arc lamps within the town. This supply scheme also provided electricity to a number of shops and premises to light 34 incandescent Swan light bulbs. Additionally, Robert Hammond, in December 1881, demonstrated the new electric light in the Sussex town of Brighton in the UK for a trial period. The ensuing success of this installation enabled Hammond to put this venture on both a commercial and legal footing, as a number of shop owners wanted to use the new electric light. Thus the Hammond Electricity Supply Co. was launched. Whilst the Godalming and Holborn Viaduct Schemes closed after a few years the Brighton Scheme continued on, and supply was in 1887 made available for 24 hours per day. In early 1882, Edison opened the world’s first steam-powered electricity generating station at Holborn Viaduct in London, where he had entered into an agreement with the City Corporation for a period of three months to provide street lighting. In time he had supplied a number of local consumers with electric light. The method of supply was direct current (DC). It was later on in the year in September 1882 that Edison opened the Pearl Street Power Station in New York City and again it was a DC supply. It was for this reason that the generation was close to or on the consumer's premises as Edison had no means of voltage conversion. The voltage chosen for any electrical system is a compromise. Increasing the voltage reduces the current and therefore reduces the required wire thickness. Unfortunately it also increases the danger from direct contact and increases the required insulation thickness. Furthermore, some load types were difficult or impossible to make work with higher voltages. The overall effect was that Edison's system required power stations to be within a mile of the consumers. While this could work in city centres, it would be unable to economically supply suburbs with power.〔Shock and Awe: The Story of Electricity - 2. The Age of Invention〕 The mid to late 1880's saw the introduction of alternating current (AC) systems in Europe and the U.S. AC power had an advantage in that transformers, installed at power stations, could be used to raise the voltage from the generators, and transformers at local substations could reduce voltage to supply loads. Increasing the voltage reduced the current in the transmission and distribution lines and hence the size of conductors and distribution losses. This made it more economical to distribute power over long distances. Generators (such as hydroelectric sites) could be located far from the loads. AC and DC competed for a while, during a period called the War of Currents. The DC system was able to claim slightly greater safety, but this difference was not great enough to overwhelm the enormous technical and economic advantages of alternating current which eventually won out.〔 The AC power system used today developed rapidly, backed by industrialists such as George Westinghouse with Mikhail Dolivo-Dobrovolsky, Galileo Ferraris, Sebastian Ziani de Ferranti, Lucien Gaulard, John Dixon Gibbs, Carl Wilhelm Siemens, William Stanley, Jr., Nikola Tesla, and others contributed to this field. While high-voltage direct current (HVDC) is increasingly being used to transmit large quantities of electricity over long distances or to connect adjacent asynchronous power systems, the bulk of electricity generation, transmission, distribution and retailing takes place using alternating current. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Electric power industry」の詳細全文を読む スポンサード リンク
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