UNDERSTANDING WIND POWER GENERATORS FOR HOME USE
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Concerns for the environment and the desire to be independent from utility cause increasing interest in various renewable energy sources. There is plenty of information on this subject scattered throughout the web. It is just not always easy to quickly find reliable practical data among a myriad of web sites. This site is designed as a concise online reference guide for anyone looking for practical facts on wind power generation for the home.
THE BASIC FACTS
We know that energy can't be created, but can only convert from one form to another. So, let's quickly review how winds are formed and where does their energy come from.
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Solar electromagnetic radiation heats our atmosphere unevenly.
This process, coupled with the Earth rotation, different rates of heating of land and water, and irregularities of the Earth's surface creates unequal air pressure distributions, which in turn contribute to the flows of air. Note that any moving object has kinetic energy, which is proportional to the mass of the object and the square of its speed: E=mv2/2. The energy in the wind is due to the moving air molecules. Thus, when an air stream is formed, a portion of the sun's irradiance (about 1-2% of what reached the Earth) is converted to the energy of the moving air. That's why wind energy is often referred to as a converted form of solar energy. It has been in use for several millennia and it's one of the five main alternative power sources. Originally people utilized wind to power sailing ships. Later on they began using it in grinding or milling turbines. For more than a century it has also been used for generation of electricity. Electricity powered by the moving air is casually referred to as wind power, and the device that converts air movement into electricity is called wind generator.
Not surprisingly, such machine comes in various sizes. For example, rotors in sailboat battery charges can be just a few feet in diameter. Utility-grade systems have rotors measuring hundreds of feet across. Likewise, depending on the size, the peak output ratings can range anywhere from several watt to megawatts. For a reference, the world largest turbine has 417-ft rotor and is rated for 7.5 MW.
HOW WIND GENERATORS WORK
In short, a wind generator operates like inverse fan. Its main components are rotor, alternator, structural support and control electronics.
The rotor assembly includes the aerodynamically designed blades for transferring kinetic air energy to the rotation of the shaft. Most modern wind turbines have two to five blades. The rotor is connected to the main shaft of the alternator. The alternator in turn converts the mechanical energy of the spinning shaft into electricity. It contain