What is a wind energy turbine?
Wind is a form of solar power that can be managed and reaped into wind energy. The flow of wind is motion energy. And this motion energy is harnessed into mechanical energy by wind energy generators. Wind energy turbines are specialized wind energy generators that generate electricity by harvesting the wind resource. Being the most modernized technique of generating electricity, wind turbines are used majorly these days. Wind is a kinetic energy formed due to the uneven heating of earthís surfaces due to its irregularities, rotation of the earth and the scratchy heating of the atmosphere by the sunís rays. The water bodies and vegetative covering also contribute to the differential heating. Thus there is a constant temperature difference between the earthís equator and its poles. This temperature difference causes wind flow from the cooler areas to the comparatively hotter regions of the earth. This wind flow is a kinetic energy in itself which is further regenerated into electricity by a wind energy converter.
Wind Energy Turbines: types and functions
Wind energy turbines are broadly classified into two varieties namely, the horizontal-axis type and the vertical-axis type. The classification is based on the orientation of the axis around which the turbine rotates. The horizontal wind turbine rotates around a horizontal axis and is the common variety largely used to generate electricity. A horizontal-axis turbine mainly consists of a rotor shaft, two or three blades and an electric generator. The blades are pointed in the direction of the wind. The movement of the blades moves the shaft mechanically and the generator connected to the shaft uses this mechanical energy into electricity. Thus the electricity produced is directly proportional to the speed of wind, rather the speed of the propeller blades. Some advanced wind energy turbines use a gearbox to turn the slow rotation of the blades into a faster rotation to ensure an efficient driving of the electrical generator. Wind turbines that are mounted on a high tower, say hundred feet capture the most energy as the wind at such a height is less turbulent and much faster.
Turbulence is usually produced behind a wind turbine tower and that is why the turbine is normally pointed upwind of the wind tower. To prevent the wind turbine blades from being pushed into the tower by heavy winds, the wind turbine blades are usually made very stiff. Besides, the blades are tilted a little up and placed wide apart in front of the tower to prevent forcing into the wind turbine tower. The downwind type is also built as they do not require the additional mechanics for holding the blades in the direction of the wind. In high wind, however, the wind resistance is reduced due to the fatigue failures thus pulling down its efficiency. The horizontal-axis wind turbines can again be divided into 3 subtypes like the 12th century windmills, the 19th century windmills and the modern wind turbines, the last one being the most evolved and modernized device.
Vertical-axis wind turbine has the main rotor shaft vertically oriented. Thus this turbine does not require to be pointed in the direction of wind to be effective. This is a big advantage in areas where wind direction is variable and unpredictable too. Wind from different directions is easily and efficiently utilized by the vertical-axis wind turbines. Besides all these advantages the vertical-axis wind turbine has some basic limitations (cannot be installed on high towers due to the huge size) which clearly discourage the large scale usage of this device to generate electricity.
Advantages and disadvantages of wind energy turbines
Wind energy turbines have proved themselves to be quite rewarding in generating electricity. The tall tower bases help capture high winds that ensure a high power output. Also since the modern technology helps control the angle of the turbine blades remotely thereby increasing the control over the same, the turbine can collect the most wind energy. The wind energy turbines, though are basically useful to the whole world, still pose some issues in their operations. The transportation of the huge blades (around 90 meters long) is a serious issue. The tall towers require huge, expensive cranes for their installation which is again a botheration. The tower construction required is just huge to bear the loads of the gearbox, generator and heavy blades. Also the avian mortality (bats and birds being killed while flying into the rotors) and noise pollution issues (generated by the rotor blades) along with the visual impact (the huge machinery that block the view of the landscape) cannot be ruled out at all. Despite all the pros and cons the wind energy is an asset being a renewable resource that is clean and pollution free.