Welcome to wind energy!
Using the wind's power to create electricity has been around for a while- you have probably seen windmills on farms. When the wind turns the blades of a windmill, and it spins a turbine inside a small generator to produce electricity.
A windmill on a farm can not make a big amount of electricity - enough to power a couple farm machines. To make enough electricity to serve many people, power companies build "wind farms" with dozens of very, super duper, large wind turbines.
Wind farms are built in smooth, open areas because the wind blows at least 14 miles per hour. Currently, Iowa currently has more than 600 wind turbines, making enough electricity to power 140,000 homes. Wisconsin and Minnesota are also home to wind farms – and the number is growing very quickly.
Some schools in the Midwest have their very own wind farms! In Spirit Lake, Iowa, the school playground is right under two wind turbines.
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How a wind turbine works-
A wind turbine works the opposite of a fan. Instead of using electricity to make wind, a turbine uses wind to make electricity.
The wind turns the blades, which spin a shaft, which connects to a generator and creates electricity. The electricity is sent through transmission and distribution lines to a substation, then on to homes, business and schools.
Calculating Power
To calculate the amount of power a turbine can actually generate from the wind, you need to know the wind speed at the turbine site and the turbine power rating. Most large turbines produce their maximum power at wind speeds around 15 meters per second (33 mph). Considering steady wind speeds, it's the diameter of the rotor that determines how much energy a turbine can generate. Keep in mind that as a rotor diameter increases, the height of the tower increases as well, which means more access to faster winds.
Rotor Size and Maximum Power Output
Rotor Diameter (meters) Power Output (kW)
10 25
17 100
27 225
33 300
40 500
44 600
48 750
54 1000
64 1500
72 2000
80 2500
ADVANTAGES OF WIND POWER:
1. The wind is free and with modern technology it can be captured efficiently.
2. Once the wind turbine is built the energy it produces does not cause green house gases or other pollutants.
3. Although wind turbines can be very tall each takes up only a small plot of land. This means that the land below can still be used. This is especially the case in agricultural areas as farming can still continue.
4. Many people find wind farms an interesting feature of the landscape.
5. Remote areas that are not connected to the electricity power grid can use wind turbines to produce their own supply.
6. Wind turbines have a role to play in both the developed and third world.
7. Wind turbines are available in a range of sizes which means a vast range of people and businesses can use them. Single households to small towns and villages can make good use of range of wind turbines available today
DISADVANTAGES OF WIND POWER:
1. The strength of the wind is not constant and it varies from zero to storm force. This means that wind turbines do not produce the same amount of electricity all the time. There will be times when they produce no electricity at all.
2. Many people feel that the countryside should be left untouched, without these large structures being built. The landscape should left in its natural form for everyone to enjoy.
3. Wind turbines are noisy. Each one can generate the same level of noise as a family car traveling at 70 mph.
4. Many people see large wind turbines as unsightly structures and not pleasant to look at. They disfigure the countryside and are generally ugly.
5. When wind turbines are being manufactured some pollution is produced. Therefore wind power does produce some pollution.
6. Large wind farms are needed to provide entire communities with enough electricity. For example, the largest single turbine available today can only provide enough electricity for 475 homes, when running at full capacity.
Wind power is also becoming more economical to produce: technological innovations have brought the cost of wind power down from more than 30 cents per kilowatt-hour during the 1980s to less than 6 cents per kilowatt hour today.
Wind farms are modular, so additional turbines can be added if the needed.
Wind power can be adapted for residential use, but it's rarely cost-effective on such a small scale. Most residential wind systems are found on ranches or other remotes areas of the western United States, where the homes and other structures are located far from existing power lines.
BIBLIOGRAPHY
http://www.alliantenergykids.com/stellent2/groups/public/documents/pub/phk_ee_re_001502.hcsp
http://science.howstuffworks.com/wind-power.htm
http://www.alliantenergykids.com/stellent2/groups/public/documents/pub/phk_ee_re_001502.hcsp
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