Wind is usually known as the stuff that makes your hair blow around in the air on a blustery day. The movement of wind, though, actually has a specific pattern of behavior rather than a random flow. Wind is the movement of air from an area of high pressure and temperature to an area of low pressure and temperature. Hot air rises, so cool air must fill in the empty spaces left behind. Wind exists because the sun unevenly heats the surface of the Earth, creating this disparity between hot and cool air (“Wind Power”).
People have been harnessing the wind’s power for many purposes throughout time. Sailors used the wind to travel the oceans; farmers used windmills to grind grain for food production or to extract and pump groundwater, and now, we use wind turbines to generate electricity.
Given that energy is a critical resource for the world’s growing population, wind is a promising source of clean, renewable energy. There is no air or water pollution with wind power, and since wind is free (assuming of course that no evil mastermind is currently at work figuring out a way to control wind patterns), the “fuel” costs are zero once the turbine is built (“Wind Power”).
Wind is essentially a moving gas and like all matter, it is formed of particles. Motion means kinetic energy, so what wind turbines do is capture the kinetic energy in the wind. This energy can then be transferred from one medium into another, namely into electric energy.
There are three essential parts to a wind turbine. The rotor blades act as “barriers” to the wind. When the wind forces the blades to move, kinetic energy is transferred from the wind to the blades. Then, the wind-turbine shaft is connected to the center of the rotor and acts as a bridge between the rotor and the third component, the generator. When the rotor spins, the shaft spins as well, transferring the wind’s kinetic energy into the shaft’s rotational energy. The shaft then transfers this mechanical, rotational energy from the rotor to the generator.
The generator uses properties of electromagnetic induction to produce electrical voltage. Voltage is the force that moves electricity from one point to another as electrical current. The shaft is attached to an assembly of permanent magnets surrounding a coil of wire, so when the rotor spins the shaft, the shaft spins these magnets, generating voltage in this coil. This voltage then drives the electrical current out through power lines for distribution.
The diameter of the rotor determines how much energy a turbine can generate. The larger the rotor, the more kinetic energy is harnessed. Furthermore, a larger rotor requires a taller tower, the height of which grants the rotor access to faster winds (Layton).
The biggest wind turbines, which can be as tall as a 20-story building with 200-foot-long blades (see image below for one huge example from Blade Dynamics in New Orleans), generate enough electricity to supply 600 U.S. homes. A single megawatt of electricity can power 250 homes, and in 2012 alone, 13.2 gigawatts of wind energy were produced worldwide, with the U.S. contributing 5.5 gigawatts to this total (Woody).
If this clean, renewable resource continues to show such promise, then it is predicted that one third of the world’s electricity will be generated by wind power by the year 2050 (“Wind Power”), an exciting prospect for sustainably managing the world’s growing population and growing energy demands.
Written by Constance Kaita
Images courtesy of www.macfarlanegenerators.com.au and John McCusker, The Times-Picayune (www.nola.com)
Layton, Julia. “How Wind Power Works.” HowStuffWorks.com. 9 August 2006. Web. 1 July 2013.
“Wind Power.” National Geographic. n.d. Web. 1 July 2013.
Woody, Todd. “U.S. Installed Record 13.2 Gigawatts of Wind Energy in 2012.” Forbes. 18 January 2013. Web. 1 July 2013.