2. In general, windmills were used as early as 200 B.C. in Persia. Windmills first appeared in Europe during the middle ages, around 11 th to 12 th centuries. What’s more, there are also evidence prove that the German crusaders were taking their windmill-making skills to Syria around 1190. The first electricity generating wind turbine was invented by Scottish academic James Blyth to light his holiday home in Marykirk, Scotland in July 1887. Several months later an American inventor named Charles F Brush invented his first automatically operating wind turbines and put it into use.

3. Long story short, more and more people including physicians, scientists and celebrities were starting to notice the importance of wind power and were willing to put their money and time into producing wind turbines. By the time 1900s, there are already 2500 windmills in Denmark, facilitating their local citizen’s lives, producing power of about 30 MW. Finally, in the fall 1941, Vermont introduced its first megawatt-class wind turbine to the world.

4. In most of wind turbines, the blades are attached to an axle that runs into a gearbox, or transmission, which steps up the speed of the rotation. Then, the faster spinning shaft spins inside the generator and this can produces AC electricity. The right voltage and frequency are needed to produce electricity to be compatible with a utility grid.

5. However the speed of generator may vary due to the variation of the wind, speed producing fluctuations in the electricity. One solution to this problem is using constant speed turbines, where the blades adjust when the speed of wind changes. Another solution is using variable- speed turbines, where the blades and generator both change speeds with the wind. A third solution is using low-speed generators.

6. 1.Clean : No fossil fuels are burnt during the generation from wind energy to the electricity. 2. Save Space: It uses less space than other power stations. Therefore, the space saved can be used for other purposes. 3.Low Cost: The wind is FREE !!! We can also make millions of dollars from this free source. 4.Flexibility: It can generate energy at remote area, like mountains and countryside. In addition, It can be made in a range of different sizes in order to serve varying population areas. 5.Steady: It combined with solar electricity, which will provide a steady and reliable supply of electricity.

7. 1.Unreliability: At some places, the wind is not strong enough to support the wind turbine to generate electricity. 2.Inefficiency: It produces much less electricity than fossil fueled power station. 3.Expensive: Its construction fee is really high. 4.Noise Pollution: It will produce a lot of noise, which will disturb people’s life around. 5.Ugly: The wind turbine looks ugly. This will destory the countryside’s beauty.

8. Wind energy has been developed dramatically in a few short decades. Because of technological advancements, policy initiatives and economic drivers, a large number of wind turbines have been sprouted up globally. According to statistics of the online resources “Windustry”, by the end of 2007 94,000MW of wind is installed around the world. Among all the countries around the world, United States’ growth of using wind energy is the fastest. Whereas, Germany has the highest total wind capacity of 22.3GW. Wind energy brings great benefits to our society. It is a renewable and clean energy source which can be used locally. It has been the world’s fastest growing renewable energy source with an average annual growth rate of over 20%.

10. * http://www.clean-energy- ideas.com/articles/advantages_and_disadvanta ges_of_wind_energy.html http://www.clean-energy- ideas.com/articles/advantages_and_disadvanta ges_of_wind_energy.html * http://www.windustry.org/ http://www.windustry.org/ * http://www.ucsusa.org/clean_energy/technolo gy_and_impacts/energy_technologies/how- wind-energy- works.html#The_Mechanics_of_Wind_Turbines http://www.ucsusa.org/clean_energy/technolo gy_and_impacts/energy_technologies/how- wind-energy- works.html#The_Mechanics_of_Wind_Turbines * http://en.wikipedia.org/wiki/Wind_turbinehttp://en.wikipedia.org/wiki/Wind_turbine