Generating Electricity !

Generating Electricity !

An interactive animation illustrating electricity generation. A coil rotates clockwise and counter-clockwise in a magnetic field, inducing an a.c. current.

Electricity is most often generated at a power station by electromechanical generators, primarily driven by heat engines fueled by chemical combustion or nuclear fission but also by other means such as the kinetic energy of flowing water and wind. Other energy sources include solar photovoltaics and geothermal power.

Electricity generation is the process of generating electric power from other sources of primary energy. The fundamental principles of electricity generation were discovered during the 1820s and early 1830s by the British scientist Michael Faraday.

Fossil fuel power plants burn carbon fuels such coal, oil or gas to generate steam that drives large turbines that produce electricity. These plants can generate electricity reliably over long periods of time.

Electricity generation is the process of generating electric power from other sources of primary energy. For electric utilities, it is the first process in the delivery of electricity to consumers. The other processes, electricity transmissiondistribution, and electrical power storage and recovery using pumped-storage methods are normally carried out by the electric power industry. Electricity is most often generated at a power station by electromechanical generators, primarily driven by heat engines fuelled by combustion or nuclear fission but also by other means such as the kinetic energy of flowing water and wind. Other energy sources include solar photovoltaics and geothermal power.

 

Methods of generating electricity:

There are seven fundamental methods of directly transforming other forms of energy into electrical energy.

Static electricity:

Static electricity, form the physical separation and transport of charge (examples: triboelectric effect and lightning). It was the first form discovered and investigated, and the electrostatic generator is still used even in modern devices such as the Van de Graaff generator and MHD generators.

Electromagnetic induction:

In Electromagnetic induction, an electric generator, dynamo or alternator transforms kinetic energy into electricity. This is the most used form for generating electricity and is based on Faraday's law. It can be experimented by rotating a magnet within closed loops of a conducting material (e.g. copper wire). Almost all commercial electrical generation is done using electromagnetic induction, in which mechanical energy forces a generator to rotate.

Turbines:

Almost all electrical power on Earth is generated with a turbine, driven by wind, water, steam or burning gas. The turbine drives a generator. There are many different methods of developing mechanical energy, including heat engines, hydro, wind and tidal power. Most electric generation is driven by heat engines. The combustion of fossil fuels supplies most of the heat to these engines, with a significant fraction from nuclear fission and some from renewable sources. The modern steam turbine(invented by Sir Charles Parsons in 1884) currently generates about 80% of the electric power in the world using a variety of heat sources. Power sources include:

  • Steam

    Large dams such as Three Gorges Dam in China can provide large amounts of hydroelectric power; it has a 22.5 GW capability.
    • Water is boiled by coal burned in a thermal power plant, about 41% of all electricity is generated this way.
    • Nuclear fission heat created in a nuclear reactor creates steam. Less than 15% of electricity is generated this way.
    • Renewables. The steam is generated by Biomass, Solar thermal energy where solar parabolic troughs and solar power towersconcentrate sunlight to heat a heat transfer fluid, which is then used to produce steam, or Geothermal power.
    • Natural gas: turbines are driven directly by gases produced by combustion. Combined cycle are driven by both steam and natural gas. They generate power by burning natural gas in a gas turbine and use residual heat to generate steam. At least 20% of the worlds electricity is generated by natural gas.
  • Small turbines can be powered by Diesel engines. This is used for back up generation, usually at low voltages. Most large power grids also use diesel generators, originally provided as emergency back up for a specific facility such as a hospital, to feed power into the grid during certain circumstances.
  • Water Energy is captured from the movement of water. From falling water, the rise and fall of tides or ocean thermal currents. Each driving a water turbine to produce approximately 16% of the world's electricity. The Perth Wave Energy Project is an early production, submerged buoy, electrical power and direct desalination installation supplying power to HMAS Stirling in Western Australia.
  • The windmill was a very early wind turbine. In a solar updraft tower wind is artificially produced. Before 2010 less than 2% of the worlds electricity was produced from wind.

Electrochemistry:

 

Large dams such as Hoover Damcan provide large amounts of hydroelectric power; it has 2.07 GW capability.

Electrochemistry is the direct transformation of chemical energy into electricity, as in a battery. Electrochemical electricity generation is important in portable and mobile applications. Currently, most electrochemical power comes from batteries. Primary cells, such as the common zinc-carbon batteries, act as power sources directly, but many types of cells are used as storage systems rather than primary generation systems. Open electrochemical systems, known as fuel cells, can be used to extract power either from natural fuels or from synthesized fuels. Osmotic power is a possibility at places where salt and fresh water merges.

Photovoltaic effect:

The photovoltaic effect is the transformation of light into electrical energy, as in solar cells. Photovoltaic panels convert sunlight directly to electricity. Although sunlight is free and abundant, solar electricity is still usually more expensive to produce than large-scale mechanically generated power due to the cost of the panels. Low-efficiency silicon solar cells have been decreasing in cost and multijunction cells with close to 30% conversion efficiency are now commercially available. Over 40% efficiency has been demonstrated in experimental systems.Until recently, photovoltaics were most commonly used in remote sites where there is no access to a commercial power grid, or as a supplemental electricity source for individual homes and businesses. Recent advances in manufacturing efficiency and photovoltaic technology, combined with subsidies driven by environmental concerns, have dramatically accelerated the deployment of solar panels. Installed capacity is growing by 40% per year led by increases in Germany, Japan, and the United States.

Thermoelectric effect:

A coal-fired power plant in Laughlin, Nevada U.S.A. Owners of this plant ceased operations after declining to invest in pollution control equipment to comply with pollution regulations.

Thermoelectric effect is the direct conversion of temperature differences to electricity, as in thermocouples, thermopiles, and thermionic converters.

Piezoelectric effect:

The Piezoelectric effect generates electricity from the mechanical strain of electrically anisotropic molecules or crystals. Researchers at the United States Department of Energy's Lawrence Berkeley National Laboratory have developed a piezoelectric generator sufficient to operate a liquid crystal display using thin films of M13 bacteriophage. Piezoelectric devices are used for power generation from mechanical strain, particularly in power harvesting.

Nuclear transformation:

Nuclear transformation is the creation and acceleration of charged particles (examples: betavoltaics or alpha particle emission). The direct conversion of nuclear potential energy to electricity by beta decay is used only on a small scale. In a full-size nuclear power plant, the heat of a nuclear reaction is used to run a heat engine. This drives a generator, which converts mechanical energy into electricity by magnetic induction. Betavoltaics are a type of solid-state power generator which produces electricity from radioactive decay. Fluid-based magneto hydrodynamic (MHD) power generation has been studied as a method for extracting electrical power from nuclear reactors and also from more conventional fuel combustion systems.

 

 

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