How Generators in Power Stations Work
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Power generation is based on the 1831 discovery by Michael Faraday, which showed that moving a magnet within a coil of wire can generate an electric current.
Generators are based on the connection between magnetism, motion and electricity. Generators typically use an electromagnet, which is created by electricity and a rapidly spinning turbine to produce massive amounts of current.
The standard generator contains a group of insulated wire coils in the shape of a cylinder. Within the cylinder is a rotary electromagnet. When the magnet spins, it induces a tiny current in each part of the wire coil. Each part of the wire coil then turns into a small, individual electric conductor and the tiny currents of individual sections merge to create a single large current. Resulting electricity is then sent through power lines to consumers.
There are two predominant categories of electrical generators, those that use non-renewable energy sources, and those that use renewable energy.
Non-Renewable Power Generation
Non-renewable energy sources include fossil fuels such as coal, oil and natural gas, as well as nuclear fuels such as refined uranium.
In power plants that use non-renewable sources, the incineration of fuel or the energy released by nuclear fuel generates heat. This energy is used to boil water, creating superheated steam that is maintained at high pressure. A steam turbine then channels this pressurized steam to push a series of blades attached to a shaft, causing the shaft to rotate inside a generator. An electromagnet within the generator creates an electrical current.
Power stations based on non-renewable fuel sources are a dependable source of energy because they can supply on-demand power.
Because they take so long to start producing power from start-up, nuclear and coal-based power stations generally supply 'baseload' electricity, meaning they are continually operating. Oil and gas-based power stations tend to supply electricity at peak demand times.
The main drawbacks of this type of power generation are the limited availability of fuels sources, and the substantial release of carbon dioxide into the atmosphere, which has been linked to climate change. The incineration of coal and gas also releases sulphur dioxide, which can cause breathing issues and the toxic phenomenon known as acid rain.
Furthermore, the waste produced by nuclear plants is highly toxic and must be safely sequestered somewhere.
Renewable Power Generation
Continuously being replaced by nature, there are several different kinds of renewable energy sources, including wind, wave and hydroelectric power. Solar radiation can also be used to produce electricity; however, this kind of power generation does not involve a turbine or mechanical generator.
Wind turbines have massive windmill-type blades on top of a large tower. When the wind blows, it strikes the blades and when it blows strong enough, the blades spin, turning a shaft that drives the generator. Wind turbines are often grouped in windy locations to create wind farms.
Wave turbines use wave energy converters (WECs) to capture the motion or kinetic energy of waves. Some WECs are positioned perpendicularly against a water surface and others are positioned laterally along a water surface. Regardless of the approach, WECs are designed to drive a turbine, producing electricity.
Hydroelectric power stations use the kinetic energy of falling water to generate electrical energy. Some hydroelectric power stations use water falling from a dam in a river valley and others capture the natural energy generated by a large waterfall. When water falls, its gravitational potential energy is converted into kinetic energy. A hydroelectric facility channels this rushing water through tubes, causing the water to drive turbines. Hydroelectric power is very dependable and currently generates considerable amounts of electricity.
Hydroelectric and other forms of renewable energy resources are considered "clean" because they do not generate any emissions. While their supply of energy comes from nature, making it essentially free, renewable power generators are relatively expensive to install. Renewable sources such as wind and solar are also heavily dependent on weather: Wind turbines only turn when there is sufficient wind and solar cells generate significantly less electricity during cloudy weather.
References and Further Reading
- Virtual Chembook - Elmhurst College: http://chemistry.elmhurst.edu/vchembook/193sources.html
- BBC: https://www.bbc.com/bitesize/guides/zbsdmp3/revision/1
- U.S Energy Information Administration: https://www.eia.gov/energyexplained/index.php?page=electricity_generating
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