Wind farm is not a farm where the “wind” is fed, but a plant using the wind to generate electricity. As the population is ever-increasing, more and more wind farms are built nowadays as they generate electricity in a renewable way. When we visit a wind farm, the large wind turbines are standing one by one, these “giants” are actually the producers for the electricity that being operated on simple principles. The wind turbines are determined to use upwind side to face the wind while downwind side faces away, this whole process is remained by the drive and motor yaws (located in the tower of a wind turbine) which are designed to orient the upwind turbines to keep facing the changeable directions of the wind. To generate the daily electricity, the wind turbine is made of three fan-like blades, a rotor, pitch system, low-speed shaft, one gearbox, a generator, high-speed shaft, and yaw wire in the tower. The blades will be blown and spin around the rotor when the natural wind is provided, the faster the wind moves, the faster the blades spin. The pitch system, which is connected to the rotor, is used to control the specific speed and prevent it from turning in winds that are too high or too low to produce electricity. After the speed is regulated, the low-speed shaft is able to limit the turns at about 30-60 rpm (rotations per minute) and leads the gearbox, which connects the low-speed shaft to the high-speed shaft and increases the speed that is required by the generator to produce electricity, to work. Then the generator, with the activation of the high-speed shaft, will produce 60-cycle AC electricity and transfer them into the yaw wire in the tower. Once all of the electricity produced by the wind turbines are gathered in the substation through the wires, it will be conveyed to the grids and been used in different places. The energy pathway could be seen in the whole process, wind turbines transform the kinetic energy in wind into electrical energy when the wind spins the blades, the rotor will capture the kinetic energy of the wind and convert it into rotational energy and motion to lead the generator in order to produce the electricity.In the term of the benefits, natural wind resources are inexhaustible and the use of wind power can reduce environmental pollution, without producing any greenhouse emissions, and save conventional energy sources such as coal and oil. “Wind farm” technology is mature in most of the countries, it has relatively low cost in renewable energy and broad prospects in development of the power generation, which can be flexibly applied. What is more, the wind farm is able to be operated easily both in the grid and independently from it, which can also be used as a complementary power generation system with other technologies. It is also true that the land used to construct wind turbines could still be used for farming and grazing. On the other hand, turbines generate electricity when wind is blowing. The ecological problems of wind turbines are likely to interfere the wild birds, for example, the Kansas grouse in USA disappeared after the wind turbines were built. The current solution for this problem is building offshore wind farms, although these farms are more efficient, it is actually more expensive relatively. In some areas, such as Taiwan, wind power is not economically viable, as the demand for electricity is high in summer and daytime, but there is less wind during that time. Additionally, wind farms require a lot of land to build so as to produce more energy at the same time. They could emit noises and cause inconvenience to the pubic nearby, so open space is necessary to be occupied. Rising concerns about the adverse health effects of wind farms are increasing, some of the residents living nearby have an opportunity to be influenced by the electromagnetic wave. These people may start awake sometimes with the noise sounding as though a truck is coming in and suffer frequent nosebleeds and headaches, as well as a feeling of fuzziness in the head and physical tiredness. According to the analyzations of cons and pros above, some people believe the benefits weight much more, their counterparts think the drawbacks are more important. This dilemma causes the controversial views about the wind farms. To concern about the efficiency, the blades are usually designed to reduce stresses on them and the pitch system and slow-speed shaft are used to slow them down, which means people cannot take full advantage of really high wind speeds. The blades are similar to airplane wings, blowing air passes around the both sides of the blade, the shape of it causes the pressure to be uneven, higher on one side of the blade and lower on the other. This type of design makes the blade bear an unbalanced stress and does not allow the wind to be used completely. The speed used by the turbines is called survival wind speed (the maximum wind speed that a given wind turbine is designed to withstand above which it can not survive), which is selected by pitch system. The loss of wind power from different speeds occurs at this moment as really high and low speeds of wind are ignored. If the wind turbines could convert all the wind’s power to mechanical power, it is ideally possible to adjust the efficiency to 100% .Overall, building wind farms is a double-edged sword, we should balance the positives and negatives brought by it in order to gain more electricity generated by renewable sources so that a better and more environmentally-friendly society could be constructed.