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AÂ wind turbine is a device for convertingÂ windÂ power to mechanical with a low velocityÂ turbineÂ designed for compressible fluids
This information on wind turbine history comes from an article written by Michael Berge of the Berge Wind power Company, "Small Wind Turbines: A Primer on Small Wind Turbines". The wind has been an important source of energy in the U.S. for a long time. The mechanical windmill was one of the two "high-technology" inventions (the other was barbed wire) of the late 1800's that allowed us to develop much of our western frontier.
Over 8 million mechanical windmills have been installed in the US since the 1860's and some of these units have been in operation for more than a hundred years. Back in the 1920's and 1930's, before the REA began subsidizing rural electric coops and electric lines, farm families throughout the Midwest used 200-3,000 watt wind generators to power lights, radios, and kitchen appliances. The modest wind industry that had built up by the 1930's was literally driven out of business by government policies favoring the construction of utility lines and fossil fuel power plants.
Â Description: Windmill
In the late 1970's and early 1980's intense interest was once again focused on wind energy as a possible solution to the energy crisis. As homeowners and farmers looked to various Electricity producing renewable energy alternatives, small wind turbines emerged as the most cost effective technology capable of reducing their utility bills. Tax credits and favorable federal regulations (PURPA) made it possible for over 4,500 small, 1-25 kW, utility-intertie wind systems to be installed at individual homes between 1976-1985. Another 1,000 systems were installed in various remote applications during the same period.
Small wind turbines were installed in all fifty States. None of the small wind turbine companies, however, were owned by large companies committed to long term market development, so when the federal tax credits expired in late 1985, and oil prices dropped to $10 a barrel two months later, most of the small wind turbine industry once again disappeared.
Parts of Wind Turbine :
1)Â Fan blades: The wind turbines comprises of the large fan blades which are connected to the hub.
2)Â Shaft: The hub is mounted on the shaft. When the atmospheric wind blows over the fan blades they start rotating, due to this the shaft also starts rotating. If the wind blows very fast the brakes are applied to control the speed of rotation of fan blades and the shaft.
3)Â Transmission gearbox: The speed of rotation of the shaft is very slow and it is not sufficient to produce the Electricity. To increase the output speed the shaft is connected to the gear box.
4)Â Output from the gearbox: The input is given to large gear of the gearbox rotating at slow speed and output is obtained from the small gear hence the speed of the output shaft increases.
Sections of wind turbines :
We have here two sections by power .
In this time , wind is also used by Electricity. When the wind spins the propellers on a wind turbine, a generator is subsequently turned on and produces electric power.
Wind farms are a series of single, often quite tall, wind turbine towers that combined can produce significant amounts of Electricity. Wind farms are usually constructed in areas that experience high and frequent winds such as coastal areas, open plains and hill tops, and are typically positioned above obstacles like buildings and trees to allow for maximum efficiency. As concerns over the use of fossil fuels rise, wind farms are increasingly being built to help provide power for electrical grids and utility providers. Wind farms have received some criticism for obstructing visibility and producing unsettling noise.
Types of Wind Turbines
Wind turbines can be separated into two basic types determined by which way the turbine spins. Wind turbines that rotate around a horizontal axis are more common (like a wind mill), while vertical axis wind turbines are less frequently used (Savonius and Darrieus), however, my personal favorite.
Horizontal Axis Wind Turbines (HAWT)
Horizontal axis wind turbines, also shortened to HAWT, are the common style that most of us think of when we think of a wind turbine. A HAWT has a similar design to a wind mill, it has blades that look like a propeller that spin on the horizontal axis.
Horizontal axis wind turbines have the main rotor shaft and electrical generator at the top of a tower, and they must be pointed into the wind. Small turbines are pointed by a simple wind vane placed square with the rotor (blades), while large turbines generally use a wind sensor coupled with a servo motor. Most large wind turbines have a gearbox, which turns the slow rotation of the rotor into a faster rotation that is more suitable to drive an electrical generator.
Since a tower produces turbulence behind it, the turbine is usually pointed upwind of the tower. Wind turbine blades are made stiff to prevent the blades from being pushed into the tower by high winds. Additionally, the blades are placed a considerable distance in front of the tower and are sometimes tilted up a small amount.
Downwind machines have been built, despite the problem of turbulence, because they don't need an additional mechanism for keeping them in line with the wind, and because in high winds, the blades can be allowed to bend which reduces their swept area and thus their wind resistance. Since turbulence leads to fatigue failures, and reliability is so important, most HAWTs are upwind machines.
Cyclic stresses and vibration
When the turbine turns to face the wind, the rotating blades act like a gyroscope. As it pivots, gyroscopic precession tries to twist the turbine into a forward or backward somersault. For each blade on a wind generator's turbine, force is at a minimum when the blade is horizontal and at a maximum when the blade is vertical. This cyclic twisting can quickly fatigue and crack the blade roots, hub and axle of the turbines.
Vertical axis wind turbines, as shortened to VAWTs, have the main rotor shaft arranged vertically. Â The main advantage of this arrangement is that the wind turbine does not need to be pointed into the wind. This is an advantage on sites where the wind direction is highly variable or has turbulent winds.http://centurionenergy.net/images/stories/20090305-small-vertical-axis-wind-turbine.jpg
With a vertical axis, the generator and other primary components can be placed near the ground, so the tower does not need to support it, also makes maintenance easier. The main drawback of a VAWT generally create drag when rotating into the wind.
It is difficult to mount vertical-axis turbines on towers, meaning they are often installed nearer to the base on which they rest, such as the ground or a building rooftop. The wind speed is slower at a lower altitude, so less wind energy is available for a given size turbine. Air flow near the ground and other objects can create turbulent flow, which can introduce issues of vibration, including noise and bearing wear which may increase the maintenance or shorten its service life. However, when a turbine is mounted on a rooftop, the building generally redirects wind over the roof and this can double the wind speed at the turbine. If the height of the rooftop mounted turbine tower is approximately 50% of the building height, this is near the optimum for maximum wind energy and minimum wind turbulence.
Darrieus wind turbine
Darrieus wind turbines are commonly called "Eggbeater" turbines, because they look like a giant eggbeater. They have good efficiency, but produce large torque ripple and cyclic stress on the tower, which contributes to poor reliability. Also, they generally require some external power source, or an additional Savonius rotor, to start turning, because the starting torque is very low. The torque ripple is reduced by using three or more blades which results in a higher solidity for the rotor. Solidity is measured by blade area over the rotor area. Newer Darrieus type turbines are not held up by guy-wires but have an external superstructure connected to the top bearing.
Wind Turbine Design and Construction
In this six-day hands-on workshop, you will learn how to make a quiet and durable wind turbine from scratch. You'll develop knowledge and skills in basic Electricity, wood working, metal working, resin casting, and a variety of other topics. Students will complete at least two wind turbines of different sizes, and work towards the completion of a third if time permits. We will also assemble and install a short tower, if time permits, or install the turbine on an existing tower, time permitting, once again. These turbines are designed for battery-charging systems.
This is an excellent opportunity for you to learn a variety of skills. The turbines we will build are ideal for those who are interested in building their own wind power systems from scratch for fun, to save money, or for generating power in the developing world. Time will be spent each day in lecture learning about Electricity, homebrew wind turbines, wind energy, wind turbine design, towers, wind site assessment, and wind systems.
Students will fabricate the 3-phase axial flux alternators, wooden blades, and the metal frame work for the turbines from scratch. This is an ambitious workshop so expect to stay busy! Students will not take home a wind turbine with them. However, some of the wind turbines made during the workshop will be for sale to participants.
Record - holding turbines
TheÂ Enercon E-126Â has a rated capacity of 7.58Â MWÂ Â , has an overall height of 198Â m (650Â ft), a diameter of 126Â m (413Â ft), and is the world's largest-capacity wind turbine since its introduction in 2007.Â
At least four companies are working on the development of a 10MW turbine:
Wind Power LtdÂ are developing a 10Â MW VAWT, the Aero generator X
Clipper Wind powerÂ are developing the Britannia 10Â MW HAWT
SwayÂ announced the proposed development of a prototype 10Â MW wind turbine with a height of 162.5Â m (533Â ft) and a rotor diameter of 145Â m (475Â ft).
Largest swept area
The turbine with the largest swept area is a prototype installed byÂ GamesaÂ atÂ Jaulín,Â Zaragoza, Spain in 2009. The G10X - 4.5 MW has a rotor diameter of 128m.Â
The tallest wind turbine isÂ Fuhrländer Wind Turbine Laasow. Its axis is 160 meters above ground and its rotor tips can reach a height of 205 meters. It is the only wind turbine taller than 200 meters in the world.
Le Nordais wind farm inÂ Cap-Chat, QuebecÂ has aÂ vertical axis wind turbineÂ (VAWT) named Éole, which is the world's largest at 110 m.Â It has aÂ nameplate capacityÂ of 3.8MW.
The turbines currently operating closest to theÂ South PoleÂ are threeÂ Enercon E-33Â inÂ Antarctica, powering New Zealand'sÂ Scott BaseÂ and the United States'Â McMurdo StationÂ since December 2009Â although a modified HR3 turbine from Northern Power Systems operated at the Amundsen-Scott South Pole StationÂ in 1997 and 1998.Â In March 2010Â CITEDEFÂ designed, built and installed a wind turbine in Argentine Marambio Base.
Four turbines at RønlandÂ wind farmÂ in Denmark share the record for the most productive wind turbines, with each having generated 63.2Â GWh by June 2010
The world's highest-situated wind turbine is made byÂ DeWindÂ and located in the Andes, Argentina around 4,100Â metres (13,500 ft) above sea level. The site uses a type D8.2Â - 2000Â kWÂ / 50Â Hz turbine. This turbine has a new drive train concept with a special torque converter (WinDrive) made byÂ VoithÂ and a synchronous generator. The WKA was put into operation in December 2007 and has supplied the Veladero mine ofÂ Barrick GoldÂ with Electricity since then.
Advantages and Disadvantages
1. The wind is free
2.Â The wind turbine it's produces does not cause any of pollutants.
3.Â Each one of wind turbine takes up only a small plot of land
4.Â Some people find wind farms an interesting feature.
5.Â Remote areas that are not connected to the Electricity power grid can use wind turbines to produce their own supply..
6.Â the wind turbine available in any size
Disadvantages of Wind Power
1.The strength of the wind is not constant . that's mean it's don't give you same amount of Electricity.
2.Â Wind turbines are noisy.
3.Â When wind turbines are being manufactured some pollution is produced. Therefore wind power does produce some pollution.