Wind turbines harness the power of the wind and use it to generate electricity. Simply stated, wind turbines work the opposite of a fan. Instead of using electricity to make wind—like a fan—wind turbines use wind to make electricity. The wind turns the blades, . Wind turns the propeller-like blades of a turbine around a rotor, which spins a generator, which creates electricity. Wind is a form of solar energy caused by a combination of three concurrent events: The sun unevenly heating the atmosphere Irregularities of the earth's surface.
Wind turbineapparatus used to convert the kinetic energy of wind into electricity. Wind turbines come in several sizes, with small-scale models used for providing electricity to rural homes or cabins and community -scale models used for providing electricity to a small number of homes within a community.
At industrial scales, many large turbines are collected into wind farms located in rural areas or offshore. The term windmillwhich typically refers to the conversion of wind energy into power turbien what is in a wind turbine or pumping, is sometimes used to describe a wind turbine.
However, the term wind turbine is widely used in mainstream references to renewable energy see also wind power. There are two primary types of wind turbines used in implementation of wind energy systems: horizontal-axis wind turgine HAWTs and vertical-axis wind turbines VAWTs. HAWTs are the most commonly used type, and winc turbine possesses two or three blades or a disk containing many turbinw multibladed type attached to each turbine.
VAWTs are able to harness what is rated r in movies blowing wjnd any direction and windd usually made with blades that rotate around a vertical pole. HAWTs are characterized as either high- ln low-solidity devices, in which solidity refers to the percentage of the swept area containing utrbine material. High-solidity HAWTs include the multibladed types that cover the total area swept by the blades with solid material in order to maximize the total amount of wind coming into contact with the blades.
An example of the high-solidity HAWT is the multibladed turbine used for pumping water on farms, often seen in the landscapes of the American West. Low-solidity HAWTs most often use two or three long blades and resemble aircraft propellers in appearance.
Low-solidity HAWTs have a low proportion of material within the swept area, which turbinr compensated by a faster rotation speed used to fill up what is the cset exam swept area.
Low-solidity HAWTs are the most commonly used commercial wind turbines as well as the type most often represented through media sources. Those HAWTs offer the greatest efficiency in electricity generation and, therefore, are among the most cost-efficient designs used. The less-used, mostly experimental VAWTs include designs that vary in shape and method of harnessing wind energy. Given that limitation, the expected power generated from a wnd wind turbine is estimated from a wind speed power curve derived for each turbine, usually represented as a graph showing the relation between power generated wha and wind speed metres per second.
The wind speed power curve varies according to variables unique to each turbine such as number of blades, blade shape, rotor swept area, and speed of rotation. The wind speed frequency distribution is a histogram representing wind speed classes and the frequency of hours per year that are expected for each wind speed class. The data for those histograms are usually provided by wind speed measurements collected at the site and used to calculate the number of hours observed for each wind speed class.
A rough estimate of annual electric production in kilowatt-hours per year at a site can be calculated from a formula multiplying average annual wind speed, swept area of the turbine, the number of turbines, and a factor estimating turbine performance at the site. However, additional factors may decrease annual energy production estimates to iw degrees, including loss of energy because of distance of transmission, as well as availability that is, how reliably the turbine will produce wijd when the wind is blowing.
By the early 21st century most commercial wind turbines functioned at over 90 percent availability, with some ls functioning at 98 percent availability.
Wind turbine. Videos Images. Additional Info. More About Contributors Article History. Home Technology Industry Wind turbine what function does the liver do. Print print Print. Table Of Contents. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Facebook Twitter. Give Feedback External Websites. Let us know if you have suggestions to improve this article requires login. External Websites. Christopher A. See Article History.
Get a Britannica Premium subscription and gain what is organisational skills in the workplace to exclusive content. Subscribe Now.
Load Next Page.
The wind makes the blades turn, which start to move with wind speeds of around m/s and provide maximum power with a wind speed 11 m/s. With very strong winds (25 m/s), the blades are feathered and the wind turbine slows down in order to prevent excessive voltages. Wind turbine towers are % domestically sourced, blade and hub components are % domestic, and nacelle assemblies are over 90% domestically sourced. However, many internal parts such as pitch and yaw systems, bearings, bolts, and controllers are . There are two primary types of wind turbines used in implementation of wind energy systems: horizontal-axis wind turbines (HAWTs) and vertical-axis wind turbines (VAWTs). HAWTs are the most commonly used type, and each turbine possesses two or three blades or a disk containing many blades (multibladed type) attached to each turbine.
A wind turbine is a machine that converts the wind's kinetic energy into rotary mechanical energy, which is then used to do work. In more advanced models, the rotational energy is converted into electricity, the most versatile form of energy, by using a generator.
For thousands of years people have used windmills to pump water or grind grain. Even into the twentieth century tall, slender, multi-vaned wind turbines made entirely of metal were used in American homes and ranches to pump water into the house's plumbing system or into the cattle's watering trough.
After World War I, work was begun to develop wind turbines that could produce electricity. Marcellus Jacobs invented a prototype in that could provide power for a radio and a few lamps but little else. When demand for electricity increased later, Jacobs's small, inadequate wind turbines fell out of use.
The first large-scale wind turbine built in the United States was conceived by Palmer Cosslett Putnam in ; he completed it in The machine was huge. The tower was Putnam's wind turbine could produce 1, kilowatts of electricity, or enough to meet the needs of a small town. It was, however, abandoned in because of mechanical failure.
With the s oil embargo, the United States began once more to consider the feasibility of producing cheap electricity from wind turbines. In the prototype Mod-O was in operation. This was a kilowatt turbine with two yard meter blades. Currently, the United States Department of Energy is aiming to go beyond 3, kilowatts per machine.
Many different models of wind turbines exist, the most striking being the vertical-axis Darrieus, which is shaped like an egg beater. The model most supported by commercial manufacturers, however, is a horizontal-axis turbine, with a capacity of around kilowatts and three blades not more than 33 yards 30 meters in length. Wind turbines with three blades spin more smoothly and are easier to balance than those with two blades.
Also, while larger wind turbines produce more energy, the smaller models are less likely to undergo major mechanical failure, and thus are more economical to maintain.
Wind farms have sprung up all over the United States, most notably in California. Wind farms are huge arrays of wind turbines set in areas of favorable wind production. The great number of interconnected wind turbines is necessary in order to produce enough electricity to meet the needs of a sizable population. Currently, 17, wind turbines on wind farms owned by several wind energy companies produce 3. A wind turbine consists of three basic parts: the tower, the nacelle, and the rotor blades.
The tower is either a steel lattice tower similar to electrical towers or a steel tubular tower with an inside ladder to the nacelle. The first step in constructing a wind turbine is erecting the tower. Although the tower's steel parts are manufactured off site in a factory, they are usually assembled on site. The parts are bolted together before erection, and the tower is kept horizontal until placement.
A crane lifts the tower into position, all bolts are tightened, and stability is tested upon completion. Next, the fiberglass nacelle is installed. Its inner workings—main drive shaft, gearbox, and blade pitch and yaw controls—are assembled and mounted onto a base frame at a factory. The nacelle is then bolted around the equipment. At the site, the nacelle is lifted onto the completed tower and bolted into place.
Most towers do not have guys, which are cables used for support, and most are made of steel that has been coated with a zinc alloy for protection, though some are painted instead. The tower of a typical American-made turbine is approximately 80 feet tall and weighs about 19, pounds. The nacelle is a strong, hollow shell that contains the inner workings of the wind turbine. Usually made of fiberglass, the nacelle contains the main drive shaft and the gearbox.
It also contains the blade pitch control, a hydraulic system that controls the angle of the blades, and the yaw drive, which controls the position of the turbine relative to the wind. The generator and electronic controls are standard equipment whose main components are steel and copper. A typical nacelle for a current turbine weighs approximately 22, pounds. The most diverse use of materials and the most experimentation with new materials occur with the blades.
Although the most dominant material used for the blades in commercial wind turbines is fiberglass with a hollow core, other materials in use include lightweight woods and aluminum. Wooden blades are solid, but most blades consist of a skin surrounding a core that is either hollow or filled with a lightweight substance such as plastic foam or honeycomb, or balsa wood. A typical fiberglass blade is about 15 meters in length and weighs approximately 2, pounds. Wind turbines also include a utility box, which converts the wind energy into electricity and which is located at the base of the tower.
Various cables connect the utility box to the nacelle, while others connect the whole turbine to nearby turbines and to a transformer. Before consideration can be given to the construction of individual wind turbines, manufacturers must determine a proper area for the siting of wind farms. Winds must be consistent, and their speed must be regularly over If the winds are stronger during certain seasons, it is preferred that they be greatest during periods of maximum electricity use.
In California's Altamont Pass, for instance, site of the world's largest wind farm, wind speed peaks in the summer when demand is high. In some areas of New England where wind farms are being considered, winds are strongest in the winter, when the need for The nacelle is a strong, hollow shell that contains the inner workings of the wind turbine, such as the main drive shaft and the gearbox.
Wind farms work best in open areas of slightly rolling land surrounded by mountains. These areas are preferred because the wind turbines can be placed on ridges and remain unobstructed by trees and buildings, and the mountains concentrate the air flow, creating a natural wind tunnel of stronger, faster winds. Wind farms must also be placed near utility lines to facilitate the transfer of the electricity to the local power plant.
Unlike most manufacturing processes, production of wind turbines involves very little concern with quality control. Because mass production of wind turbines is fairly new, no standards have been set. Efforts are now being made in this area on the part of both the government and manufacturers.
While wind turbines on duty are counted on to work 90 percent of the time, many structural flaws are still encountered, particularly with the blades. Cracks sometimes appear soon after manufacture. Mechanical failure because of alignment and assembly errors is common. Electrical sensors frequently fail because of power surges. Non-hydraulic brakes tend to be reliable, but hydraulic braking systems often cause problems.
Plans are being developed to use existing technology to solve these difficulties. Wind turbines do have regular maintenance schedules in order to minimize failure. Every three months they undergo inspection, and every six months a major maintenance checkup is scheduled.
This usually involves lubricating the moving parts and checking the oil level in the gearbox. It is also possible for a worker to test the electrical system on site and note any problems with the generator or hookups.
A wind turbine that produces electricity from inexhaustible winds creates no pollution. By comparison, coal, oil, and natural gas produce one to two pounds of carbon dioxide an emission that contributes to the greenhouse effect and global warming per kilowatt-hour produced.
When wind energy is used for electrical needs, dependence on fossil fuels for this purpose is reduced. The current annual production of electricity by wind turbines 3. Wind turbines are not completely free of environmental drawbacks. Many people consider them to be unaesthetic, especially when huge wind farms are built near pristine wilderness areas. Bird kills have been documented, and the whirring blades do produce quite a bit of noise. Efforts to reduce these effects include selecting sites that do not coincide with wilderness areas or bird migration routes and researching ways to reduce noise.
The future can only get better for wind turbines. The potential for wind energy is largely untapped. The United States Department of Energy estimates that ten times the amount of electricity currently being produced can be achieved by By , seventy times current production is possible.
If this is accomplished, wind turbines would account for 10 percent of the United States' electricity production. Research is now being done to increase the knowledge of wind resources. This involves the testing of more and more areas for the possibility of placing wind farms where the wind is reliable and strong.
Plans are in effect to increase the life span of the machine from five years to 20 to 30 years, improve the efficiency of the blades, provide better controls, develop drive trains that last longer, and allow for better surge protection and grounding. The United States Department of Energy has recently set up a schedule to implement the latest research in order to build wind turbines with a higher efficiency rating than is now possible.
The efficiency of an ideal wind turbine is That is, Turbines in actual use are about 30 percent efficient. The United States Department of Energy has also contracted with three corporations to research ways to reduce mechanical failure.
This project began in the spring of and will extend to the end of the century. Wind turbines will become more prevalent in upcoming years. The largest manufacturer of wind turbines in the world, U. Windpower, plans to expand from megawatt capacity 4, machines to megawatts 8, machines by They plan to have 2, megawatts 20, machines by the year Other wind turbine manufacturers also plan to increase the numbers produced.
International committees composed of several industrialized nations have formed to discuss the potential of wind turbines. Efforts are also being made to provide developing countries with small wind turbines similar to those Marcellus Jacobs built in the s. Denmark, which already produces 70 percent to 80 percent of Europe's wind power, is developing plans to expand manufacture of wind turbines.
The turn of the century should see wind turbines that are properly placed, efficient, durable, and numerous.