Wind Power Essay Research Paper The wind

Wind Power Essay, Research Paper

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 < 0.016. 3) The elevation

difference between the highest and lowest point must be 1/3 or less of the

height difference between the bottom of the rotor disk and the lowest

point in the terrain strip. The surface roughness of the terrain upon

which the windmill is to be built must be low. If it varies by more than

10%, this is no good. The terrain must be smooth, and consistently so. A

rough surface has more of a negative effect on the wind than a s mooth

surface. There is a value n, called, which is assigned to the terrain in

terms of its roughness. This value is used to calculate the height of the

windmill. For instance, over the sea, the index location, n is 0.14.

Over rough inland country, n is 0.34.

Turbines

Windmills are turbines. The two names can be used synonymously.

Turbines are a means of harnessing the a fluid’s power (the wind) by

converting the kinetic energy of the fluid (the wind) into mechanical

power (the rotating shaft) When the shaft of a w indmill is hooked up to a

generator, electrical energy can be formed. The generator can be used to

produce either DC or AC current. Generators that produce DC can be

connected to batteries, an inverter to produce AC, or to power DC loads.

Some generato rs are connected to heating coils. Generators that produce

AC can be hooked up to AC motors such as water pumps. Windmills are NOT

efficient. At the very most, a windmill can extract only 16/27ths of the

kineti

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