Electricity

:Separate-but related articles are Electrical energy, and Electric power

Electric power

See main article: Electric power.

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"Electric power" is the popular name given to electrical energy production and distribution. For most consumers, electrical energy is generated centrally by utility companies using coal, natural gas, hydropower, nuclear power or petroleum. In 2000, U.S. electric utilities had 600 gigawatts of maximum summer generating capacity including 261 GW from coal, 118 GW from natural gas, 92 GW from hydropower, 86 GW from nuclear and 41 GW from petroleum. Little generating capacity is presently based on renewable energy sources such as solar power and wind power. Some individuals and communities prefer renewable sources because there is less pollution and because users of renewable energy sources can sometimes gain a measure of economic independence from the electrical utilities.

Related Topics:
Electrical energy - Utility companies - Coal - Natural gas - Hydropower - Nuclear power - Petroleum - Renewable energy - Solar power - Wind power

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Devices powered by electrical energy include lamps, computers and the Internet, radio and television, refrigeration, air conditioning, traffic signals, electric guitars and other electronic musical instruments, and the spark plugs in automobiles. A summary of the applications of electric energy (written for non-specialists, and briefly explaining motors, transformers, transistors, digital, etc.) is the book, Industrial Electronics for Engineers, Chemists, and Technicians, by D. J. Shanefield, William Andrew Publishing (Norwich, NY), 2001.

Related Topics:
Computer - Internet - Radio - Television - Refrigeration - Air conditioning - Traffic signal - Electric guitar - Electronic musical instrument - Spark plug - Automobile

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Safety in power systems

It is often important that one side of a circuit be electrically bonded to an earth terminal. Such an earth terminal is usually connected to an electrode buried in the ground. The potential of earth (ground) is defined as zero by convention, and the electrical resistance between similarly buried electrodes is usually low enough that all earth terminals within a given area can be considered to be at the same voltage.

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This raises the safety level in every electric circuit.

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Applications

In electrical engineering, the energy in electromagnetic fields is harnessed to perform useful work—either as a method to transmit energy to the appropriate place and then convert it back into a different, useful form of energy (for instance, heat, light, or motion), or by using the presence or level of electricity to convey information.

Related Topics:
Electrical engineering - Information

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Producing electrical energy

See also: Electricity generation

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There are many different types of generators used to produce electrical energy: Hydropower, nuclear power, solar power, and wind power. These different types of generators use different natural and man-made materials to liberate energy.

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Hydropower

See main article: Hydropower

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Hydropower consists in taking advantage of water falling or flowing, most of the time at waterfalls or rivers, to convert the mechanical energy into electrical energy by using generators coupled to turbines.

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Nuclear power

See main article: nuclear power

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Nuclear power uses heat generated by nuclear fission of either uranium or plutonium to heat a liquid, usually water. This heat then drives a steam engine to turn a generator and produce electrical energy. Nuclear fusion generates greater energy than fission. However, a convenient and cheaper way of harnessing fusion is still being researched.

Related Topics:
Nuclear fission - Uranium - Plutonium - Steam engine - Fusion

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Solar power

See main article: Solar power

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Solar power is created by the sun's radiant energy falling on the earth. The energy from the sun excites electrons in a semiconductor material which gives rise to a photo voltaic potential.

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Wind power

See main article: wind power

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Energy is captured from the wind by the use of wind turbines. The most common type of wind turbine is three-bladed, though two- and four-bladed ones can be found. Most turbines have blades that rotate perpendicular to the wind, though there is a variety that rotates parallel to it.

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Wind turbines must be placed in an area where there is an almost constant source of wind. The most productive locations are on or near the shore of a large lake, sea or ocean, though they can be placed anywhere that there is a breeze.

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Burning of fuel

See main article: Fossil fuel power plant

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Energy is captured from the heat given off by coal, oil, wood and fossil fuels. These are often used when no other means of energy generation can be used, either because of the local geography or technical issues. It is also one of the worst polluting type of generator.

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