How is Electricity Created from Wind?

Wind has power as anyone who has seen the aftermaths of a hurricane or tornado can attest. Wind has been used to propel mighty sailing ships and move the massive millstones that grind grains into flour, but what is wind and how is it used in the modern world to create electricity?

Wind is created by differences in temperature between air in two locations. Hotter temperatures mean more energy, colder, less. According to the laws of thermodynamics, heat energy attempts to equalize, and it is the movement of air between areas of differing temperature that creates the wind.

So what does that mean? Well, wind has the ability to push--a sail, a millstone or a magnet. The force of the wind drives a rotating axle connected to a drive train that moves a magnet back and forth through a coil. Why a magnet? That takes us to the second scientific principal: induction. Have you ever wondered how we get electricity?

There are several ways to create electricity, but power-plants do so by using dynamos. Dynamos are essentially a large, circular magnet known as a coil and another bar-shaped magnet that is pulled in and out of the coil the same way a person would put a ring on his hand and then take it off. The power of the wind is used to push the bar magnet through the coil.

Picture a person repeatedly and rapidly putting on and removing a ring. The ring, a coil, is magnetized. So is the finger, or bar magnet that is moved in and out of the coil. If you did this to your finger, you would get a sore and blistered finger, but when you move two magnets this way, electricity is produced as the lines of magnetic force in the bar-magnetic cut across the lines of magnetic force in the coil. This is known as an induced current.

Electricity and magnetism are not two different forces, but two sides of the same coin, and electricity can be turned into a magnet as well. That is the principal behind electromagnets that are used to pick up scrap in a scrap yard. When you turn off the electricity, no more magnet.

This interchangeability of electricity and magnets was first described by Faraday and is known as Faraday's law of induction. It describes how a dynamo, an electromagnet, a microphone or the diaphragm that turns the spoken word into electrical current for transmission in a telephone works.

When you the bar magnet moves back and forth through the coil, the current direction will reverse as the bar is moved through the ring and then reversed back. How fast the direction changes is known as the electricity's cycle, and the voltage or electrical pressure of the electrical current will be determined by how many times the copper wire is wound through the coil.

Compare voltage to water flowing through a pipe. If you pump a large amount of water through a thin pipe or a hose with a narrow opening, it will emerge with tremendous force. Take the same amount of water and put it through a large pipe or a completely open fire hydrant and it will dribble onto the ground.

The amount of current generated in a system is expressed in amps, just like the amount of water in a pipe is expressed in liters or gallons. The same amount of amps sent through a different number of windings in a coil allows the electrical pressure, expressed in volts, to vary. When you increase the number of windings in the coil the electrical pressure increases just as water becomes more forceful when fed through a thinner pipe. When fewer winds are used in the coil, voltage decreases.

When a power plant distributes voltage it uses as step-up transformer to increase the voltage in the line before the power is transmitted. This step-up transformer is a coil with many windings. Once the power reaches your home a step-down transformer with fewer coils reduces the electrical pressure so you don't blow every light in your home and set the place on fire.

Once the voltage is stepped down, it must also be turned into direct current or current that runs in only one direction. Alternating current (AC) can be passed through a resister, a material that conducts electricity poorly, to create heat for electric blankets and toasters, but AC current would be useless for running vacuum cleaners or other motor-powered appliances.

To turn this alternating current into a one-way current that can power common electrical appliances, a part called a rectifier is used. This rectifier acts something like a filter that allows only current flowing in a particular direction through. Electrical appliances like motors for fans and vacuum cleaners use rectifiers to make sure that their parts only spin in one direction.

To sum up, the wind moves a magnet through a magnetized coil to produce electricity through induction. The current's electrical pressure, known as voltage, is stepped up and transmitted through electrical lines to your home where another transformer lowers the voltage and rectifiers on your appliances make sure that only current flowing in the desired direction is used. And this is how the potential energy in wind is converted to electrical power for your home.

Sources:

http://www.physlink.com/education/askexperts/ae280.cfm
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html
http://resources.schoolscience.co.uk/CDA/16plus/copelech4pg3.html