Wind Power Essays - Wind Power, Wind, Aerodynamics,

Wind Power annon The wind turbine, also called a windmill, is a means of harnessing the kinetic energy of the wind and converting it into electrical energy. This is accomplished by turning blades called aerofoils, which drive a shaft, which drive a motor (turbine) and ar e connected to a generator. It is estimated that the total power capacity of winds surrounding the earth is 1 x 1011 Gigawatts (Cheremisinoff 6). The total energy of the winds fluctuates from year to year. Windmill expert Richard Hills said that the wind really is a fickle source of power, with wind speeds to low or inconsistent for the windmill to be of practical use. However, that hasn't stopped windmill engineers from trying. Today, there are many kinds of windmills, some of which serve differen t functions. They are a complex alternative energy source. What to consider when building a windmill In choosing where to build a windmill, there are many important factors to consider. First is the location: 1) Available wind energy is usually higher near the seacoast or coasts of very large lakes and offshore islands. 2) Available wind energy is gene rally high in the central plains region of the U.S. because of the wide expanses of level (low surface roughness) terrain. 3) Available wind energy is generally low throughout the Southeastern U.S. except for certain hills in the Appalachian and Blue Rid ge Mountains, the North Carolina coast, and the Southern tip of Florida. This is because of the influence of the Bermuda high pressure system, which is a factor especially during the summer. Also important to consider is the wind where you are going to build: 1) the mean wind speed (calculated my cubing the averages and taking the mean of the cubes) and its seasonal variations. 2) The probability distribution of wind speed and of extreme wi nds. The mean wind speed must be high enough, and the distribution must be so that all the data points are very similar. 3) The height variation of wind speed and wind direction. Wind cannot be too high or too low in relation to the ground or it is too difficult to harness. 4) The gustiness of the wind field in both speed and direction. Gusty winds greatly affect the power output of the windmills and are usually harmful. 5) The wind direction distribution and probability of sudden large shifts in di rection. The wind must be unlikely to suddenly shift direction. It must blow in the same general direction. 6) the seasonal density of the air, and variations of density of the air with height. The denser the air, the worse it will be for windmills. 7) Hazard conditions such as sandstorms, humidity, and salt-spray, which are bad for windmills. The physics behind these will be discussed later. 8) Trade winds in the subtropics, and the channeled wind through mountain passes are especially beneficial to windmills. Once a suitable location is found, the wind is analyzed extensively, and the criteria is met, there are still more requisites. 1) The terrain upon which the windmills are built must be relatively flat. The elevation difference between the turbine site and the terrain is no larger than 60 meters over a 12-km radius. You may have seen windmills such as those in California on little hills, but this is because the requirement is met. The hill may be the only one around for miles. 2) All hills must have small height to width ratios: h:l must be