Wind turbine

This article is about wind-powered electrical generators. For wind-powered machinery used to grind grain or pump water, see Windmill and Windpump.

A wind turbine is a device that converts the kinetic energy of wind into electrical energy. As of 2020^[update], hundreds of thousands of large turbines, in installations known as wind farms, were generating over 650 gigawatts of power, with 60 GW added each year.^[1] Wind turbines are an increasingly important source of intermittent renewable energy, and are used in many countries to lower energy costs and reduce reliance on fossil fuels. One study claimed that, as of 2009,^[update] wind had the "lowest relative greenhouse gas emissions, the least water consumption demands and the most favorable social impacts" compared to photovoltaic, hydro, geothermal, coal and gas energy sources.^[2]

Thorntonbank Wind Farm, using 5 MW turbines REpower 5M in the North Sea off the coast of Belgium

Smaller wind turbines are used for applications such as battery charging and remote devices such as traffic warning signs. Larger turbines can contribute to a domestic power supply while selling unused power back to the utility supplier via the electrical grid.^[3]

Wind turbines are manufactured in a wide range of sizes, with either horizontal or vertical axes, though horizontal is most common.^[4]

History

Main article: History of wind power

 

Nashtifan wind turbines in Sistan, Iran

The windwheel of Hero of Alexandria (10–70 CE) marks one of the first recorded instances of wind powering a machine.^[5] However, the first known practical wind power plants were built in Sistan, an Eastern province of Persia (now Iran), from the 7th century. These "Panemone" were vertical axle windmills, which had long vertical drive shafts with rectangular blades.^[6] Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were used in the gristmilling and sugarcane industries.^[7]

Wind power first appeared in Europe during the Middle Ages. The first historical records of their use in England date to the 11th and 12th centuries; there are reports of German crusaders taking their windmill-making skills to Syria around 1190.^[8] By the 14th century, Dutch windmills were in use to drain areas of the Rhine delta. Advanced wind turbines were described by Croatian inventor Fausto Veranzio in his book "Machinae Novae" (1595), he described vertical axis wind turbines with curved or V-shaped blades.

 

Illustration of the wind turbine for power generation erected by Josef Friedlaender at the International Electrical Exhibition in Vienna in 1883

 

James Blyth's electricity-generating wind turbine, photographed in 1891

The first electricity-generating wind turbine was installed by the Austrian Josef Friedländer at the Vienna International Electrical Exhibition in 1883. It was a Halladay windmill for driving a dynamo. Friedländer’s 22-foot (6.6-meters) diameter Halladay “wind motor” was supplied by U.S. Wind Engine & Pump Co. of Batavia, Illinois. The five horsepower windmill drove a dynamo at ground level that fed electricity into a series of batteries. The batteries powered various electrical tools and lamps, as well as a threshing machine. Friedländer’s windmill and its accessories were prominently installed at the north entrance to the main exhibition hall ("Rotunde") in the Vienna Prater.^[9][10][11]

In July 1887 Scottish academic James Blyth installed a battery-charging machine to light his holiday home in Marykirk, Scotland.^[12] Some months later, American inventor Charles F. Brush was able to build the first automatically operated wind turbine after consulting local University professors and his colleagues Jacob S. Gibbs and Brinsley Coleberd and successfully getting the blueprints peer-reviewed for electricity production.^[13] Although Blyth's turbine was considered uneconomical in the United Kingdom,^[13] electricity generation by wind turbines was more cost effective in countries with widely scattered populations.^[8]

 

The first automatically operated wind turbine, built in Cleveland in 1887 by Charles F. Brush. It was 60 feet (18 m) tall, weighed 4 tons (3.6 metric tonnes) and powered a 12 kW generator.^[14]

In Denmark by 1900, there were about 2500 windmills for mechanical loads such as pumps and mills, producing an estimated combined peak power of about 30 megawatts (MW). The largest machines were on 24-meter (79 ft) towers with four-bladed 23-meter (75 ft) diameter rotors. By 1908, there were 72 wind-driven electric generators operating in the United States from 5 kilowatts (kW) to 25 kW. Around the time of World War I, American windmill makers were producing 100,000 farm windmills each year, mostly for water-pumping.^[15]

By the 1930s, use of wind turbines in rural areas was declining as the distribution system extended to those areas.^[16]

A forerunner of modern horizontal-axis wind generators was in service at Yalta, USSR in 1931. This was a 100 kW generator on a 30-meter (98 ft) tower, connected to the local 6.3 kV distribution system. It was reported to have an annual capacity factor of 32 percent, not much different from current wind machines.^[17]

In the autumn of 1941, the first megawatt-class wind turbine was synchronized to a utility grid in Vermont. The Smith–Putnam wind turbine only ran for about five years before one of the blades snapped off.^[18] The unit was not repaired, because of a shortage of materials during the war.^[19]

The first utility grid-connected wind turbine to operate in the UK was built by John Brown & Company in 1951 in the Orkney Islands.^[13][20]

In the early 1970s, however, anti-nuclear protests in Denmark spurred artisan mechanics to develop microturbines of 22 kW despite declines in the industry.^[21] Organizing owners into associations and co-operatives led to the lobbying of the government and utilities and provided incentives for larger turbines throughout the 1980s and later. Local activists in Germany, nascent turbine manufacturers in Spain, and large investors in the United States in the early 1990s then lobbied for policies that stimulated the industry in those countries.^[22][23][24]

It has been argued that expanding the use of wind power will lead to increasing geopolitical competition over critical materials for wind turbines, such as rare earth elements neodymium, praseodymium, and dysprosium. However, this perspective has been critically dismissed for failing to relay how most wind turbines do not use permanent magnets and for underestimating the power of economic incentives for the expanded production of these minerals.^[25]

Wind power density

Main article: Wind power

Wind Power Density (WPD) is a quantitative measure of wind energy available at any location. It is the mean annual power available per square meter of swept area of a turbine, and is calculated for different heights above ground. Calculation of wind power density includes the effect of wind velocity and air density.^[26]

Wind turbines are classified by the wind speed they are designed for, from class I to class III, with A to C referring to the turbulence intensity of the wind.^[27]

Class	Avg Wind Speed (m/s)	Turbulence
IA	10	16%
IB	10	14%
IC	10	12%
IIA	8.5	16%
IIB	8.5	14%
IIC	8.5	12%
IIIA	7.5	16%
IIIB	7.5	14%
IIIC	7.5	12%

Efficiency

Conservation of mass requires that the amount of air entering and exiting a turbine must be equal. Accordingly, Betz's law gives the maximal achievable extraction of wind power by a wind turbine as 16⁄27 (59.3%) of the rate at which the kinetic energy of the air arrives at the turbine.^[28]

The maximum theoretical power output of a wind machine is thus 16⁄27 times the rate at which kinetic energy of the air arrives at the effective disk area of the machine. If the effective area of the disk is A, and the wind velocity v, the maximum theoretical power output P is:

${\displaystyle P={\frac {16}{27}}{\frac {1}{2}}\rho v^{3}A={\frac {8}{27}}\rho v^{3}A}$ ,

where ρ is the air density.

Wind-to-rotor efficiency (including rotor blade friction and drag) are among the factors affecting the final price of wind power.^[29] Further inefficiencies, such as gearbox losses, generator and converter losses, reduce the power delivered by a wind turbine. To protect components from undue wear, extracted power is held constant above the rated operating speed as theoretical power increases as the cube of wind speed, further reducing theoretical efficiency. In 2001, commercial utility-connected turbines delivered 75% to 80% of the Betz limit of power extractable from the wind, at rated operating speed.^[30][31]

Efficiency can decrease slightly over time, one of the main reasons being dust and insect carcasses on the blades, which alter the aerodynamic profile and essentially reduce the lift to drag ratio of the airfoil. Analysis of 3128 wind turbines older than 10 years in Denmark showed that half of the turbines had no decrease, while the other half saw a production decrease of 1.2% per year.^[32]

In general, more stable and constant weather conditions (most notably wind speed) result in an average of 15% greater efficiency than that of a wind turbine in unstable weather conditions, thus allowing up to a 7% increase in wind speed under stable conditions. This is due to a faster recovery wake and greater flow entrainment that occur in conditions of higher atmospheric stability. However, wind turbine wakes have been found to recover faster under unstable atmospheric conditions as opposed to a stable environment.^[33]

Different materials have varying effects on the efficiency of wind turbines. In an Ege University experiment, three wind turbines, each with three blades with a diameter of one meter, were constructed with blades made of different materials: A glass and glass/carbon epoxy, glass/carbon, and glass/polyester. When tested, the results showed that the materials with higher overall masses had a greater friction moment and thus a lower power coefficient.^[34]

The air velocity is the major contributor to the turbine efficiency. This is the reason for the importance of choosing the right location. The wind velocity will be high near the shore because of the temperature difference between the land and the ocean. Another option is to place turbines on mountain ridges. The higher the wind turbine will be, the higher the wind velocity on average. A windbreak can also increase the wind velocity near the turbine.^[35]

Types

 

The three primary types: VAWT Savonius, HAWT towered; VAWT Darrieus as they appear in operation

Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common.^[36] They can also include blades or be bladeless.^[37] Household-size vertical designs produce less power and are less common.^[38]

Horizontal axis

 

Components of a horizontal axis wind turbine (gearbox, rotor shaft and brake assembly) being lifted into position

 

The rotor of a gearless wind turbine being set. This particular turbine was prefabricated in Germany, before being shipped to the U.S. for assembly.

 

Offshore Horizontal Axis Wind Turbines (HAWTs) at Scroby Sands Wind Farm, England

 

Onshore Horizontal Axis Wind Turbines in Zhangjiakou, Hebei, China

Large three-bladed horizontal-axis wind turbines (HAWT) with the blades upwind of the tower produce the overwhelming majority of wind power in the world today.^[4] These turbines have the main rotor shaft and electrical generator at the top of a tower, and must be pointed into the wind. Small turbines are pointed by a simple wind vane, while large turbines generally use a wind sensor coupled with a yaw system. Most have a gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator.^[39] Some turbines use a different type of generator suited to slower rotational speed input. These don't need a gearbox and are called direct-drive, meaning they couple the rotor directly to the generator with no gearbox in between. While permanent magnet direct-drive generators can be more costly due to the rare earth materials required, these gearless turbines are sometimes preferred over gearbox generators because they "eliminate the gear-speed increaser, which is susceptible to significant accumulated fatigue torque loading, related reliability issues, and maintenance costs."^[40] There is also the pseudo direct drive mechanism, which has some advantages over the permanent magnet direct drive mechanism.^[41]

Most horizontal axis turbines have their rotors upwind of the supporting tower.^[42] Downwind machines have been built, because they don't need an additional mechanism for keeping them in line with the wind. In high winds, downwind blades can also be designed to bend more than upwind ones, which reduces their swept area and thus their wind resistance, mitigating risk during gales. Despite these advantages, upwind designs are preferred, because the pulsing change in loading from the wind as each blade passes behind the supporting tower can cause damage to the turbine.^[43]

Turbines used in wind farms for commercial production of electric power are usually three-bladed. These have low torque ripple, which contributes to good reliability. The blades are usually colored white for daytime visibility by aircraft and range in length from 20 to 80 meters (66 to 262 ft). The size and height of turbines increase year by year. Offshore wind turbines are built up to 8 MW today and have a blade length up to 80 meters (260 ft). Designs with 10 to 12 MW were in preparation in 2018,^[44] and a "15 MW+" prototype with three 118 meters (387 ft) blades is planned to be constructed in 2022.^[45] The average hub height of horizontal axis wind turbines is 90 meters.^[46]

Vertical axis

Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. One advantage of this arrangement is that the turbine does not need to be pointed into the wind to be effective,^[47] which is an advantage on a site where the wind direction is highly variable. It is also an advantage when the turbine is integrated into a building because it is inherently less steerable. Also, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, improving accessibility for maintenance. However, these designs produce much less energy averaged over time, which is a major drawback.^[38][48]

Vertical turbine designs have much lower efficiency than standard horizontal designs.^[49] The key disadvantages include the relatively low rotational speed with the consequential higher torque and hence higher cost of the drive train, the inherently lower power coefficient, the 360-degree rotation of the aerofoil within the wind flow during each cycle and hence the highly dynamic loading on the blade, the pulsating torque generated by some rotor designs on the drive train, and the difficulty of modelling the wind flow accurately and hence the challenges of analysing and designing the rotor prior to fabricating a prototype.^[50]

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 a rooftop mounted turbine tower is approximately 50% of the building height it is near the optimum for maximum wind energy and minimum wind turbulence. While wind speeds within the built environment are generally much lower than at exposed rural sites,^[51][52] noise may be a concern and an existing structure may not adequately resist the additional stress.

Subtypes of the vertical axis design include:

Darrieus wind turbine

Main article: Darrieus wind turbine

"Eggbeater" turbines, or Darrieus turbines, were named after the French inventor, Georges Darrieus.^[53] They have good efficiency, but produce large torque ripple and cyclical stress on the tower, which contributes to poor reliability. They also 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 greater solidity of the rotor. Solidity is measured by blade area divided by the rotor area.

Giromill

A subtype of Darrieus turbine with straight, as opposed to curved, blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and is self-starting.^[54] The advantages of variable pitch are: high starting torque; a wide, relatively flat torque curve; a higher coefficient of performance; more efficient operation in turbulent winds; and a lower blade speed ratio which lowers blade bending stresses. Straight, V, or curved blades may be used.^[55]

Savonius wind turbine

Main article: Savonius wind turbine

 

A vertical axis Twisted Savonius type turbine.

These are drag-type devices with two (or more) scoops that are used in anemometers, Flettner vents (commonly seen on bus and van roofs), and in some high-reliability low-efficiency power turbines. They are always self-starting if there are at least three scoops.^[56]

Twisted Savonius is a modified savonius, with long helical scoops to provide smooth torque. This is often used as a rooftop wind turbine and has even been adapted for ships.^[57]

Airborne wind turbine

Main article: Airborne wind turbine

Airborne wind turbines consist of wings or a small aircraft tethered to the ground.^[58] They are useful for reaching faster winds above which traditional turbines can operate. There are prototypes in operation in east Africa.^[59]

Floating wind turbine

Main article: Floating wind turbine

These are offshore wind turbines that are supported by a floating platform.^[60] By having them float, they are able to be installed in deeper water allowing more of them. This also allows them to be further out of sight from land and therefore less public concern about the visual appeal.^[61]

Unconventional types

Main article: Unconventional wind turbines

•  
  Counter-rotating wind turbine
•  
  Vertical Axis Wind Turbine offshore
•  
  Light pole wind turbine

Design and construction

Main article: Wind turbine design

 

Components of a horizontal-axis wind turbine

 

Inside view of a wind turbine tower, showing the tendon cables

Wind turbine design is a careful balance of cost, energy output, and fatigue life.

Components

Wind turbines convert wind energy to electrical energy for distribution. Conventional horizontal axis turbines can be divided into three components:

• The rotor, which is approximately 20% of the wind turbine cost, includes the blades for converting wind energy to low speed rotational energy.^[62]
• The generator, which is approximately 34% of the wind turbine cost, includes the electrical generator,^[63][64] the control electronics, and most likely a gearbox (e.g., planetary gear box),^[65] adjustable-speed drive, or continuously variable transmission^[66] component for converting the low-speed incoming rotation to high-speed rotation suitable for generating electricity.
• The surrounding structure, which is approximately 15% of the wind turbine cost, includes the tower and rotor yaw mechanism.^[62]

 

Nacelle of a wind turbine

A 1.5 (MW) wind turbine of a type frequently seen in the United States has a tower 80 meters (260 ft) high. The rotor assembly (blades and hub) measures about 80 meters (260 ft) in diameter.^[67] The nacelle, which contains the generator is 15.24 meters (50.0 ft) and weigh around 300 tons.^[68]

Turbine monitoring and diagnostics

See also: Wind turbine prognostics

Due to data transmission problems, structural health monitoring of wind turbines is usually performed using several accelerometers and strain gages attached to the nacelle to monitor the gearbox and equipment. Currently, digital image correlation and stereophotogrammetry are used to measure dynamics of wind turbine blades. These methods usually measure displacement and strain to identify location of defects. Dynamic characteristics of non-rotating wind turbines have been measured using digital image correlation and photogrammetry.^[69] Three dimensional point tracking has also been used to measure rotating dynamics of wind turbines.^[70]

Technology

 

Development in size and power of wind turbines, 1990–2016

Generally, efficiency increases along with turbine blade lengths. The blades must be stiff, strong, durable, light and resistant to fatigue.^[71] Materials with these properties include composites such as polyester and epoxy, while glass fiber and carbon fiber have been used for the reinforcing.^[72] Construction may involve manual layup or injection molding. Retrofitting existing turbines with larger blades reduces the task and risks of redesign.^[73]

As of 2021, the longest blade was 115.5 m (379 ft), producing 15 MW.^[74]

Blades usually last around 20 years, the typical lifespan of a wind turbine.^[75]

Blade materials

Materials commonly used in wind turbine blades are described below.

Glass and carbon fibers

 

A turbine blade convoy passing through Edenfield, England

The stiffness of composites is determined by the stiffness of fibers and their volume content. Typically, E-glass fibers are used as main reinforcement in the composites. Typically, the glass/epoxy composites for wind turbine blades contain up to 75% glass by weight. This increases the stiffness, tensile and compression strength. A promising composite material is glass fiber with modified compositions like S-glass, R-glass etc. Other glass fibers developed by Owens Corning are ECRGLAS, Advantex and WindStrand.^[76]

Carbon fiber has more tensile strength, higher stiffness and lower density than glass fiber. An ideal candidate for these properties is the spar cap, a structural element of a blade which experiences high tensile loading.^[72] A 100-metre (330 ft) glass fiber blade could weigh up to 50 tonnes (110,000 lb), while using carbon fiber in the spar saves 20% to 30% weight, about 15 tonnes (33,000 lb).^[77]

Hybrid reinforcements

Instead of making wind turbine blade reinforcements from pure glass or pure carbon, hybrid designs trade weight for cost. For example, for an 8-metre (26 ft) blade, a full replacement by carbon fiber would save 80% of weight but increase costs by 150%, while a 30% replacement would save 50% of weight and increase costs by 90%. Hybrid reinforcement materials include E-glass/carbon, E-glass/aramid. The current longest blade by LM Wind Power is made of carbon/glass hybrid composites. More research is needed about the optimal composition of materials ^[78]

Nano-engineered polymers and composites

Additions of small amount (0.5 weight %) of nanoreinforcement (carbon nanotubes or nanoclay) in the polymer matrix of composites, fiber sizing or inter-laminar layers can improve fatigue resistance, shear or compressive strength, and fracture toughness of the composites by 30% to 80%. Research has also shown that incorporating small amounts of carbon nanotubes (CNT) can increase the lifetime up to 1500%.^[79]

Costs

As of 2019^[update], the capital cost of a wind turbine was around $1 million per megawatt of nameplate capacity, though this figure varies by location; for example, such numbers ranged from a half million in South America to $1.7 million in Asia.^[80]

For the wind turbine blades, while the material cost is much higher for hybrid glass/carbon fiber blades than all-glass fiber blades, labor costs can be lower. Using carbon fiber allows simpler designs that use less raw material. The chief manufacturing process in blade fabrication is the layering of plies. Thinner blades allow reducing the number of layers and so the labor, and in some cases, equate to the cost of labor for glass fiber blades.^[81]

Offshore has significantly higher installation costs.^[82]

Non-blade materials

Wind turbine parts other than the rotor blades (including the rotor hub, gearbox, frame, and tower) are largely made of steel. Smaller turbines (as well as megawatt-scale Enercon turbines) have begun using aluminum alloys for these components to make turbines lighter and more efficient. This trend may grow if fatigue and strength properties can be improved. Pre-stressed concrete has been increasingly used for the material of the tower, but still requires much reinforcing steel to meet the strength requirement of the turbine. Additionally, step-up gearboxes are being increasingly replaced with variable speed generators, which requires magnetic materials.^[71]

Modern turbines use a couple of tons of copper for generators, cables and such.^[83] As of 2018^[update], global production of wind turbines use 450,000 tonnes (990 million pounds) of copper per year.^[84]

Material supply

 

Nordex wind turbine manufacturing plant in Jonesboro, Arkansas, United States

A 2015 study of the material consumption trends and requirements for wind energy in Europe found that bigger turbines have a higher consumption of precious metals but lower material input per kW generated. The material consumption and stock at that time was compared to input materials for various onshore system sizes. In all EU countries, the estimates for 2020 doubled the values consumed in 2009. These countries would need to expand their resources to meet the estimated demand for 2020. For example, the EU had 3% of world supply of fluorspar, and it would require 14% by 2020. Globally, the main exporting countries are South Africa, Mexico, and China. This is similar with other critical and valuable materials required for energy systems such as magnesium, silver and indium. The levels of recycling of these materials are very low, and focusing on that could alleviate supply. Because most of these valuable materials are also used in other emerging technologies, like light emitting diodes (LEDs), photo voltaics (PVs) and liquid crystal displays (LCDs), their demand is expected to grow.^[85]

A 2011 study by the United States Geological Survey estimated resources required to fulfill the US commitment to supplying 20% of its electricity from wind power by 2030. It did not consider requirements for small turbines or offshore turbines because those were not common in 2008 when the study was done. Common materials such as cast iron, steel and concrete would increase by 2%–3% compared to 2008. Between 110,000 and 115,000 metric tons of fiber glass would be required per year, a 14% increase. Rare-earth metal use would not increase much compared to available supply, however rare-earth metals that are also used for other technologies such as batteries which are increasing its global demand need to be taken into account. Land required would be 50,000 square kilometers onshore and 11,000 offshore. This would not be a problem in the US due to its vast area and because the same land can be used for farming. A greater challenge would be the variability and transmission to areas of high demand.^[86]

Permanent magnets for wind turbine generators contain rare-earth metals such as neodymium (Nd), praseodymium (Pr), terbium (Tb), and dysprosium (Dy). Systems that use magnetic direct drive turbines require greater amounts of rare-earth metals. Therefore, an increase in wind turbine manufacture would increase the demand for these resources. By 2035, the demand for Nd is estimated to increase by 4,000 to 18,000 tons and for Dy by 200 to 1200 tons. These values are a quarter to half of current production. However, these estimates are very uncertain because technologies are developing rapidly.^[87]

Reliance on rare earth minerals for components has risked expense and price volatility as China has been main producer of rare earth minerals (96% in 2009) and was reducing its export quotas.^[86] However, in recent years other producers have increased production and China has increased export quotas, leading to a higher supply and lower cost, and a greater viability of large scale use of variable-speed generators.^[88]

Glass fiber is the most common material for reinforcement. Its demand has grown due to growth in construction, transportation and wind turbines. Its global market might reach US$17.4 billion by 2024, compared to US$8.5 billion in 2014. In 2014, Asia Pacific produced more than 45% of the market; now China is the largest producer. The industry receives subsidies from the Chinese government allowing it to export cheaper to the US and Europe. However, price wars have led to anti-dumping measures such as tariffs on Chinese glass fiber.^[89]

Wind turbines on public display

Main article: Wind turbines on public display

 

The Nordex N50 wind turbine and visitor centre of Lamma Winds in Hong Kong, China

A few localities have exploited the attention-getting nature of wind turbines by placing them on public display, either with visitor centers around their bases, or with viewing areas farther away.^[90] The wind turbines are generally of conventional horizontal-axis, three-bladed design, and generate power to feed electrical grids, but they also serve the unconventional roles of technology demonstration, public relations, and education.^[91]

Small wind turbines

Main article: Small wind turbine

 

A small Quietrevolution QR5 Gorlov type vertical axis wind turbine in Bristol, England. Measuring 3 m in diameter and 5 m high, it has a nameplate rating of 6.5 kW to the grid.

Small wind turbines may be used for a variety of applications including on- or off-grid residences, telecom towers, offshore platforms, rural schools and clinics, remote monitoring and other purposes that require energy where there is no electric grid, or where the grid is unstable. Small wind turbines may be as small as a fifty-watt generator for boat or caravan use. Hybrid solar and wind powered units are increasingly being used for traffic signage, particularly in rural locations, as they avoid the need to lay long cables from the nearest mains connection point.^[92] The U.S. Department of Energy's National Renewable Energy Laboratory (NREL) defines small wind turbines as those smaller than or equal to 100 kilowatts.^[93] Small units often have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind.^[94]

Wind turbine spacing

On most horizontal wind turbine farms, a spacing of about 6–10 times the rotor diameter is often upheld. However, for large wind farms distances of about 15 rotor diameters should be more economical, taking into account typical wind turbine and land costs. This conclusion has been reached by research^[95] conducted by Charles Meneveau of Johns Hopkins University^[96] and Johan Meyers of Leuven University in Belgium, based on computer simulations^[97] that take into account the detailed interactions among wind turbines (wakes) as well as with the entire turbulent atmospheric boundary layer.

Recent research by John Dabiri of Caltech suggests that vertical wind turbines may be placed much more closely together so long as an alternating pattern of rotation is created allowing blades of neighbouring turbines to move in the same direction as they approach one another.^[98]

Operability

 

Workers inspect wind turbine blades

Maintenance

Wind turbines need regular maintenance to stay reliable and available. In the best case turbines are available to generate energy 98% of the time.^[99][100] Ice accretion on turbine blades has also been found to greatly reduce the efficiency of wind turbines, which is a common challenge in cold climates where in-cloud icing and freezing rain events occur.^[101] De-icing is mainly performed by internal heating, or in some cases by helicopters spraying clean warm water on the blades.^[102]

Modern turbines usually have a small onboard crane for hoisting maintenance tools and minor components. However, large, heavy components like generator, gearbox, blades, and so on are rarely replaced, and a heavy lift external crane is needed in those cases. If the turbine has a difficult access road, a containerized crane can be lifted up by the internal crane to provide heavier lifting.^[103]

Repowering

Main article: Repowering

Installation of new wind turbines can be controversial. An alternative is repowering, where existing wind turbines are replaced with bigger, more powerful ones, sometimes in smaller numbers while keeping or increasing capacity.^[104]

Demolition and recycling

Some wind turbines which are out of use are recycled or repowered.^[105][106] 85% of turbine materials are easily reused or recycled, but the blades, made of a composite material, are more difficult to process.^[107]

Interest in recycling blades varies in different markets and depends on the waste legislation and local economics. A challenge in recycling blades is related to the composite material, which is made of fiberglass with carbon fibers in epoxy resin, which cannot be remolded to form new composites.^[108]

Wind farm waste is less toxic than other garbage. Wind turbine blades represent only a fraction of overall waste in the US, according to the Wind-industry trade association, American Wind Energy Association.^[109]

Several utilities, start-up companies, and researchers are developing methods for reusing or recycling blades.^[107] Manufacturer Vestas has developed technology that can separate the fibers from the resin, allowing for reuse.^[110] In Germany, wind turbine blades are commercially recycled as part of an alternative fuel mix for a cement factory.^[107] In the United Kingdom, a project will trial cutting blades into strips for use as rebar in concrete, with the aim of reducing emissions in the construction of High Speed 2.^[111] Used wind turbine blades have been recycled by incorporating them as part of the support structures within pedestrian bridges in Poland^[112] and Ireland.^[113]

Comparison with other power sources

Advantages

Wind turbines is one of the lowest-cost sources of renewable energy along with solar panels.^[114] As technology needed for wind turbines continued to improve, the prices decreased as well. In addition, there is currently no competitive market for wind energy (though there may be in the future), because wind is a freely available natural resource, most of which is untapped.^[115] The main cost of small wind turbines is the purchase and installation process, which averages between $48,000 and $65,000 per installation. Usually, the total amount of energy harvested amount to more than the cost of the turbines.^[116]

Wind turbines provide a clean energy source,^[117] use little water,^[2] emitting no greenhouse gases and no waste products during operation. Over 1,400 tonnes (1,500 short tons) of carbon dioxide per year can be eliminated by using a one-megawatt turbine instead of one megawatt of energy from a fossil fuel.^[118]

Disadvantages

Wind turbines can be very large, reaching over 140 m (460 ft) tall and with blades 55 m (180 ft) long,^[119] and people have often complained about their visual impact.

Environmental impact of wind power includes effect on wildlife, but can be mitigated if proper strategies are implemented.^[120] Thousands of birds, including rare species, have been killed by the blades of wind turbines,^[121] though wind turbines contribute relatively insignificantly to anthropogenic avian mortality. Wind farms and nuclear power plants are responsible for between 0.3 and 0.4 bird deaths per gigawatt-hour (GWh) of electricity while fossil fuel power stations are responsible for about 5.2 fatalities per GWh. In comparison, conventional coal fired generators contribute significantly more to bird mortality.^[122]

Energy harnessed by wind turbines is variable, and is not a "dispatchable" source of power; its availability is based on whether the wind is blowing, not whether electricity is needed. Turbines can be placed on ridges or bluffs to maximize the access of wind they have, but this also limits the locations where they can be placed.^[115] In this way, wind energy is not a particularly reliable source of energy. However, it can form part of the energy mix, which also includes power from other sources. Technology is also being developed to store excess energy, which can then make up for any deficits in supplies.^[123]

Wind turbines have blinking lights that warn aircraft, to avoid collisions.^[124] Residents living near windfarms, especially those in rural areas, have complained that the blinking lights are a bothersome form of light pollution.^[124] A light mitigation approach involves Aircraft Detection Lighting Systems (ADLSs) by which the lights are turned on, only when the ADLS's radar detects aircraft within thresholds of altitude and distance.^[124]

Records

 

Éole, the largest vertical axis wind turbine, in Cap-Chat, Quebec, Canada

See also List of most powerful wind turbines

Record	Model/Name	Location	Constructor/Manufacturer
Largest and most powerful	V236-15^[125]	Østerild Wind Turbine Test Field	Vestas
Largest vertical-axis	Éole^[126]	Cap-Chat, Québec, Canada	NRC, Hydro-Québec
Largest 1-blade turbine	Monopteros M50^[127]	Jade Wind Park	MBB Messerschmitt
Largest 2-blade turbine	SCD6.5^[128]	Longyuan Wind Farm	Mingyang Wind Power
Most rotors	Four-in-One^[129]	Maasvlakte	Lagerwey
Highest-situated	2.5^[130]	Pastoruri Glaicer	WindAid
Largest offshore	Haliade-X^[74]	Netherlands	GE Wind Energy

See also

• Wind turbine design
• Compact wind acceleration turbine
• Éolienne Bollée
• IEC 61400
• Renewable energy
• Tidal stream generator
• Unconventional wind turbines
• Wind lens
• Windbelt
• Windpump

References

1. "World wind capacity at 650,8 GW, Corona crisis will slow down markets in 2020, renewables to be core of economic stimulus programmes" (Press release). WWEA. 16 April 2020. Retrieved 1 September 2021. Wind power capacity worldwide reaches 650,8 GW, 59,7 GW added in 2019
2. Evans, Annette; Strezov, Vladimir; Evans, Tim (June 2009). "Assessment of sustainability indicators for renewable energy technologies". Renewable and Sustainable Energy Reviews. 13 (5): 1082–1088. doi:10.1016/j.rser.2008.03.008.
3. "Installing and Maintaining a Small Wind Electric System". Energy.gov. Retrieved 22 May 2023.
4. Righter, Robert W. (2011). Windfall: wind energy in America today. Norman: University of Oklahoma Press. ISBN 978-0-8061-4192-3.
5. "Heron's Inventions includes Holy Water Dispenser and the Aeolipile". explorable.com. Retrieved 19 May 2023.
6. al-Hassan, Ahmad Y.; Hill, Donald R. (1992). Islamic Technology: An Illustrated History. Cambridge University Press. p. 54. ISBN 978-0-521-42239-0.
7. Hill, Donald, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64–69. (cf. Hill, Donald, Mechanical Engineering 25 December 2007 at the Wayback Machine)
8. Morthorst, Poul Erik; Redlinger, Robert Y.; Andersen, Per (2002). Wind energy in the 21st century: economics, policy, technology and the changing electricity industry. Houndmills, Basingstoke, Hampshire: Palgrave/UNEP. ISBN 978-0-333-79248-3.
9. "Austrian was First with Wind-Electric Turbine Not Byth or de Goyon". WIND WORKS. 25 July 2023. Retrieved 26 August 2023.
10. Windkraft, I. G. (2 August 2023). "Sensation: Österreicher baute bereits vor 140 Jahren das erste Windrad". www.igwindkraft.at (in German). Retrieved 26 August 2023.
11. "Die internationale elektrische Ausstellung Wien 1883 : unter besonderer Berücksichtigung der Organisation, sowie der baulichen und maschinellen Anlagen / von E. R. Leonhardt". www.e-rara.ch. 1884. Retrieved 26 August 2023.
12. "This Month in Physics History". www.aps.org. 4 June 2023. Retrieved 4 June 2023.
13. Price, Trevor J. (2004). "Blyth, James (1839–1906)". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/100957. (Subscription or UK public library membership required.)
14. . Danish Wind Industry Association. Archived from the original on 8 September 2008. Retrieved 28 December 2008.
15. . Archived from the original on 3 February 2008.
16. "History of wind power". U.S. Energy Information Administration (EIA). Retrieved 21 May 2023.
17. "History of Wind Power". encyclopedia.pub. Retrieved 31 May 2023.
18. "The Unlikely Birth of Modern Renewable Energy On A Mountain Top in Vermont – 75 Years Ago Today". Stanford Law School. 19 October 2016. Retrieved 21 May 2023.
19. Reicher, Dan (19 October 2016). "Reicher: Grampa's Knob 75th Anniversary". Vermont Public. Retrieved 6 June 2023.
20. "Tiny Islands, Big Energy: How Orkney, Scotland Is Fighting Climate Change". Pulitzer Center. Retrieved 19 May 2023.
21. "Marching Activists: Transnational Lessons for Danish Anti-Nuclear Protest". Environment & Society Portal. 21 June 2017. Retrieved 20 May 2023.
22. "WindExchange: Wind Energy Policies and Incentives". windexchange.energy.gov. Retrieved 20 May 2023.
23. Hesse, Nicole (November 2021). "Visible winds: The production of new visibilities of wind energy in West Germany , 1973–1991". Centaurus. 63 (4): 695–713. doi:10.1111/1600-0498.12420. ISSN 0008-8994. S2CID 245544055.
24. Owens, Brandon N. (2019), "Spain's Wind Power Miracle", The Wind Power Story: A Century of Innovation that Reshaped the Global Energy Landscape, IEEE, pp. 223–235, doi:10.1002/9781118794289.ch15, ISBN 978-1-118-79430-2, S2CID 240648577, retrieved 20 May 2023
25. Overland, Indra (1 March 2019). "The geopolitics of renewable energy: Debunking four emerging myths". Energy Research & Social Science. 49: 36–40. doi:10.1016/j.erss.2018.10.018. ISSN 2214-6296.
26. "NREL: Dynamic Maps, GIS Data, and Analysis Tools – Wind Maps". Nrel.gov. 3 September 2013. Retrieved 6 November 2013.
27. Appendix II IEC Classification of Wind Turbines. Wind Resource Assessment and Micro-siting, Science and Engineering. 2015. pp. 269–270. doi:10.1002/9781118900116.app2. ISBN 978-1-1189-0011-6.
28. "The Physics of Wind Turbines Kira Grogg Carleton College, 2005, p. 8" (PDF). Retrieved 6 November 2013.
29. . Bureau of Land Management. Archived from the original on 9 May 2019. Retrieved 23 April 2016.
30. (PDF). Archived from the original (PDF) on 16 May 2011.
31. Burton, Tony; Sharpe; Jenkins; Bossanyi (12 December 2001). Wind Energy Handbook. John Wiley & Sons. p. 65. ISBN 978-0-471-48997-9.
32. Wittrup, Sanne (1 November 2013). "11 års vinddata afslørede overraskende produktionsnedgang" [11 years of wind data shows surprising production decrease]. Ingeniøren (in Danish). from the original on 25 October 2018.
33. Han, Xingxing; Liu, Deyou; Xu, Chang; Shen, Wen Zhong (2018). "Atmospheric stability and topography effects on wind turbine performance and wake properties in complex terrain". Renewable Energy. Elsevier BV. 126: 640–651. doi:10.1016/j.renene.2018.03.048. ISSN 0960-1481. S2CID 115433440.
34. Ozdamar, G. (2018). "Numerical Comparison of the Effect of Blade Material on Wind Turbine Efficiency". Acta Physica Polonica A. 134 (1): 156–158. Bibcode:2018AcPPA.134..156O. doi:10.12693/APhysPolA.134.156.
35. Garisto, Dan (30 July 2021). "Windbreaks May Improve Wind Farm Power". Physics. Vol. 14. p. 112.
36. . American Wind Energy Association. Archived from the original on 23 September 2010. Retrieved 24 September 2009.
37. Stinson, Elizabeth (15 May 2015). "The Future of Wind Turbines? No Blades". Wired.
38. Paul Gipe (7 May 2014). . Wind-works.org. Archived from the original on 28 August 2022. Retrieved 29 September 2016.
39. "How a Wind Turbine Works - Text Version". Energy.gov. Retrieved 26 May 2023.
40. Bywaters, G.; Mattila; Costin; Stowell; John; Hoskins; Lynch; Cole; Cate; C. Badger; B. Freeman (October 2007). "Northern Power NW 1500 Direct-Drive Generator" (PDF). National Renewable Energy Laboratory. p. iii.
41. Neves, C. G. C.; Flores Filho, A. F.; Dorrel, D. G. (2016). "Design of a Pseudo Direct Drive for Wind Power Applications". 2016 International Conference of Asian Union of Magnetics Societies (ICAUMS). pp. 1–5. doi:10.1109/ICAUMS.2016.8479825. ISBN 978-1-5090-4383-5. S2CID 52934155.
42. "Horizontal Axis Wind Turbine - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 21 May 2023.
43. Bortolotti, Pietro; Kapila, Abhinav; Bottasso, Carlo L. (31 January 2019). "Comparison between upwind and downwind designs of a 10 MW wind turbine rotor". Wind Energy Science. 4 (1): 115–125. Bibcode:2019WiEnS...4..115B. doi:10.5194/wes-4-115-2019. ISSN 2366-7443. S2CID 197548612.
44. "MHI Vestas Launches World's First* 10 Megawatt Wind Turbine". CleanTechnica. 26 September 2018.
45. "World's biggest wind turbine shows the disproportionate power of scale". 22 August 2021.
46. "Wind Energy Factsheet". Center for Sustainable Systems. Retrieved 21 May 2023.
47. "Vertical Axis Wind Turbine - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 22 May 2023.
48. Michael Barnard (7 April 2014). "Vertical Axis Wind Turbines: Great In 1890, Also-rans In 2014". CleanTechnica.
49. Hau, E., Wind Turbines: Fundamentals, Technologies, Application, Economics. Springer. Germany. 2006
50. Michael C Brower; Nicholas M Robinson; Erik Hale (May 2010). (PDF). AWS Truepower. Archived from the original on 2 May 2013.{{cite web}}: CS1 maint: unfit URL (link)
51. Piggott, Hugh (6 January 2007). "Windspeed in the city – reality versus the DTI database". Scoraigwind.com. Retrieved 6 November 2013.
52. "Urban Wind Turbines" (PDF).
53. Möllerström, Erik; Gipe, Paul; Beurskens, Jos; Ottermo, Fredric (1 May 2019). "A historical review of vertical axis wind turbines rated 100 kW and above". Renewable and Sustainable Energy Reviews. 105: 1–13. doi:10.1016/j.rser.2018.12.022. ISSN 1364-0321. S2CID 117471815.
54. Eric Eggleston & AWEA Staff. . American Wind Energy Association. Archived from the original on 3 April 2005.
55. Marloff, Richard H. (1 January 1978). "Stresses in turbine-blade tenons subjected to bending". Experimental Mechanics. 18 (1): 19–24. doi:10.1007/BF02326553. ISSN 1741-2765. S2CID 135685029.
56. "Savonius Wind Turbine - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 23 May 2023.
57. Rob Varnon (2 December 2010). "Derecktor converting boat into hybrid passenger ferry". Connecticut Post. Retrieved 25 April 2012.
58. Cherubini, Antonello; Papini, Andrea; Vertechy, Rocco; Fontana, Marco (1 November 2015). "Airborne Wind Energy Systems: A review of the technologies". Renewable and Sustainable Energy Reviews. 51: 1461–1476. doi:10.1016/j.rser.2015.07.053. hdl:11382/503316. ISSN 1364-0321.
59. "After a Shaky Start, Airborne Wind Energy Is Slowly Taking Off". Yale E360. Retrieved 2 June 2023.
60. "So, What Exactly Is Floating Offshore Wind?". www.greentechmedia.com. Retrieved 2 June 2023.
61. "The US has just started building floating wind turbines – how do they work?". World Economic Forum. 16 December 2022. Retrieved 2 June 2023.
62. ""Wind Turbine Design Cost and Scaling Model", Technical Report NREL/TP-500-40566, December, 2006, page 35, 36" (PDF). National Renewable Energy Laboratory. Retrieved 6 November 2013.
63. Navid Goudarzi (June 2013). "A Review on the Development of the Wind Turbine Generators across the World". International Journal of Dynamics and Control. 1 (2): 192–202. doi:10.1007/s40435-013-0016-y.
64. Navid Goudarzi; Weidong Zhu (November 2012). "A Review of the Development of Wind Turbine Generators Across the World". ASME 2012 International Mechanical Engineering Congress and Exposition. 4 – Paper No: IMECE2012-88615: 1257–1265.
65. . Hansentransmissions.com. Archived from the original on 15 March 2012. Retrieved 6 November 2013.
66. Gardner, John; Haro, Nathaniel & Haynes, Todd (October 2011). (PDF). Boise State University. Archived from the original (PDF) on 7 March 2012. Retrieved 28 February 2012.
67. Bauer, Lucas. "GE General Electric GE 1.5s - 1,50 MW - Wind turbine". en.wind-turbine-models.com. Retrieved 23 May 2023.
68. "Nacelles | How are they manufactured?". Windpower Engineering & Development. Retrieved 23 May 2023.
69. Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter (2015). "Full-field dynamic strain prediction on a wind turbine using displacements of optical targets measured by stereophotogrammetry". Mechanical Systems and Signal Processing. 62–63: 284–295. Bibcode:2015MSSP...62..284B. doi:10.1016/j.ymssp.2015.03.021.
70. Lundstrom, Troy; Baqersad, Javad; Niezrecki, Christopher; Avitabile, Peter (4 November 2012). "Using High-Speed Stereophotogrammetry Techniques to Extract Shape Information from Wind Turbine/Rotor Operating Data". In Allemang, R.; De Clerck, J.; Niezrecki, C.; Blough, J.R. (eds.). Topics in Modal Analysis II, Volume 6. Conference Proceedings of the Society for Experimental Mechanics Series. Springer New York. pp. 269–275. doi:10.1007/978-1-4614-2419-2_26. ISBN 978-1-4614-2418-5.
71. Ancona, Dan; Jim, McVeigh (2001), Wind Turbine – Materials and Manufacturing Fact Sheet, CiteSeerX 10.1.1.464.5842
72. Watson, James; Serrano, Juan (September 2010). . Wind Systems. Archived from the original on 11 November 2017. Retrieved 6 November 2016.
73. Jossi, Frank (4 February 2021). "Wind developers are retrofitting newer projects with bigger, better blades". Energy News Network. Retrieved 2 June 2023.
74. Venditti, Bruno (3 June 2022). "Animation: The World's Biggest Wind Turbines". Visual Capitalist. Retrieved 20 May 2023.
75. "What happens to end-of-life wind turbine blades?". www.ny1.com. 19 August 2022. Retrieved 4 June 2023.
76. (PDF). windpower.sandia.gov. Archived from the original (PDF) on 13 August 2017. Retrieved 27 February 2018.
77. "Wind turbine blades: Glass vs. carbon fiber". www.compositesworld.com. Retrieved 12 November 2016.
78. Vries, Eize de. "Turbines of the year: Rotor blades". www.windpowermonthly.com.
79. Panduranga, Raghu; Alamoudi, Yasser; Ferrah, Azzeddine (2019). "Nanoengineered Composite Materials for Wind Turbine Blades". 2019 Advances in Science and Engineering Technology International Conferences (ASET). pp. 1–7. doi:10.1109/ICASET.2019.8714217. ISBN 978-1-5386-8271-5. S2CID 155109369.
80. "IntelStor expects wind turbine prices to recover 5% in next two years". Windpower Engineering & Development. 22 October 2019.
81. Ong, Cheng-Huat & Tsai, Stephen W. (1 March 2000). "The Use of Carbon Fibers in Wind Turbine Blade Design" (PDF). energy.sandia.gov.
82. "Onshore vs offshore wind energy: what's the difference?". National Grid Group. Retrieved 23 May 2023.
83. Frost and Sullivan, 2009, cited in Wind Generator Technology, by Eclareon S.L., Madrid, May 2012; www.eclareon.com; Available at Leonardo Energy – Ask an Expert; . Archived from the original on 26 November 2012. Retrieved 12 December 2012.
84. "Fast pace of growth in wind energy driving demand for copper". Riviera Maritime Media.
85. Kim, Junbeum; Guillaume, Bertrand; Chung, Jinwook; Hwang, Yongwoo (1 February 2015). "Critical and precious materials consumption and requirement in wind energy system in the EU 27". Applied Energy. 139: 327–334. doi:10.1016/j.apenergy.2014.11.003. ISSN 0306-2619.
86. Wilburn, David R. (2011). Wind Energy in the United States and Materials Required for the Land-Based Wind Turbine Industry from 2010 through 2030 (Scientific Investigations Report 2011-5036) (PDF). USGS. Retrieved 15 January 2023.
87. Buchholz, Peter; Brandenburg, Torsten (1 January 2018). "Demand, Supply, and Price Trends for Mineral Raw Materials Relevant to the Renewable Energy Transition Wind Energy, Solar Photovoltaic Energy, and Energy Storage". Chemie Ingenieur Technik. 90 (1–2): 141–153. doi:10.1002/cite.201700098. ISSN 1522-2640.
88. Yap, Chui-Wei (5 January 2015). "China Ends Rare-Earth Minerals Export Quotas". Wall Street Journal.
89. "Glass fiber market to reach to US$17 billion by 2024". Reinforced Plastics. 60 (4): 188–189. 1 July 2016. doi:10.1016/j.repl.2016.07.006. ISSN 0034-3617.
90. Young, Kathryn (3 August 2007). . Edmonton Journal. Archived from the original on 25 April 2009. Retrieved 6 September 2008.
91. Rudgard, Olivia (20 February 2023). "Despite perception as eyesore, wind turbine tourism takes off". The Japan Times. Retrieved 2 June 2023.
92. Anon. "Solar & Wind Powered Sign Lighting". Energy Development Cooperative Ltd. Retrieved 19 October 2013.
93. Small Wind 15 November 2011 at the Wayback Machine, U.S. Department of Energy National Renewable Energy Laboratory website
94. Castellano, Robert (2012). Alternative Energy Technologies: Opportunities and Markets. Archives contemporaines. ISBN 978-2-8130-0076-7.
95. Meyers, Johan (2011). "Optimal turbine spacing in fully developed wind farm boundary layers". Wind Energy. 15 (2): 305–317. Bibcode:2012WiEn...15..305M. doi:10.1002/we.469.
96. "New study yields better turbine spacing for large wind farms". Johns Hopkins University. 18 January 2011. Retrieved 6 November 2013.
97. M. Calaf; C. Meneveau; J. Meyers (2010). "Large eddy simulation study of fully developed wind-turbine array boundary layers". Phys. Fluids. 22 (1): 015110–015110–16. Bibcode:2010PhFl...22a5110C. doi:10.1063/1.3291077.
98. Dabiri, John O. (1 July 2011). "Potential order-of-magnitude enhancement of wind farm power density via counter-rotating vertical-axis wind turbine arrays". Journal of Renewable and Sustainable Energy. 3 (4): 043104. arXiv:1010.3656. doi:10.1063/1.3608170. S2CID 10516774.
99. van Bussel, G.J.W.; Zaaijer, M.B. (2001). (PDF). Delft University of Technology. p. 2. Archived from the original (PDF) on 12 April 2016. Retrieved 30 May 2016.
100. "Iberwind builds on 98% availability with fresh yaw, blade gains". 15 February 2016. Retrieved 30 May 2016.
101. Barber, S.; Wang, Y.; Jafari, S.; Chokani, N.; Abhari, R. S. (28 January 2011). "The Impact of Ice Formation on Wind Turbine Performance and Aerodynamics". Journal of Solar Energy Engineering. 133 (1): 011007–011007–9. doi:10.1115/1.4003187. ISSN 0199-6231.
102. Nilsen, Jannicke (1 February 2015). "Her spyler helikopteret bort et tykt lag med is". Tu.no (in Norwegian). Teknisk Ukeblad. from the original on 20 January 2021. These work .. by blowing hot air into the rotor blades so that the ice melts, or by using heating cables on the front edge of the rotor blades where the ice sticks. No chemicals are added to the water, in contrast to aircraft de-icing, which often involves extensive use of chemicals. The price tag for de-icing a wind turbine is equivalent to the value of two days' turbine production.
103. Morten Lund (30 May 2016). "Dansk firma sætter prisbelønnet selvhejsende kran i serieproduktion". Ingeniøren. from the original on 31 May 2016. Retrieved 30 May 2016.
104. "Wind Repowering Helps Set the Stage for Energy Transition". Energy.gov. Retrieved 23 May 2023.
105. Jeremy Fugleberg (8 May 2014). "Abandoned Dreams of Wind and Light". Atlas Obscura. Retrieved 30 May 2016.
106. Tom Gray (11 March 2013). . American Wind Energy Association. Archived from the original on 8 June 2016. Retrieved 30 May 2016.
107. "Wind Turbine Blades Don't Have To End Up In Landfills". The Equation. 30 October 2020. Retrieved 23 January 2022.
108. "Wind Turbine Blades Can't Be Recycled, So They're Piling Up in Landfills". Bloomberg.com. 5 February 2020. Retrieved 7 June 2023.
109. "Turbines Tossed Into Dump Stirs Debate on Wind's Dirty Downside". Bloomberg. 31 July 2019. Retrieved 6 December 2019.
110. Barsoe, Tim (17 May 2021). "End of wind power waste? Vestas unveils blade recycling technology". Reuters. Retrieved 23 January 2022.
111. "New HS2 pilot project swaps steel for retired wind turbine blades to reinforce concrete". High Speed 2. Retrieved 12 March 2021.
112. Mason, Hannah (21 October 2021). "Anmet installs first recycled wind turbine blade-based pedestrian bridge". CompositesWorld.
113. Stone, Maddie (11 February 2022). "Engineers are building bridges with recycled wind turbine blades". The Verge.
114. "Renewable Power Remains Cost-Competitive amid Fossil Fuel Crisis". www.irena.org. 13 July 2022. Retrieved 19 May 2023.
115. "Advantages and Disadvantages of Wind Energy – Clean Energy Ideas". Clean Energy Ideas. 19 June 2013. Retrieved 10 May 2017.
116. "WINDExchange: Economics and Incentives for Wind". windexchange.energy.gov. Retrieved 19 May 2023.
117. Rueter, Gero (27 December 2021). "How sustainable is wind power?". Deutsche Welle. Retrieved 28 December 2021. An onshore wind turbine that is newly built today produces around nine grams of CO2 for every kilowatt hour (kWh) it generates ... a new offshore plant in the sea emits seven grams of CO2 per kWh ... solar power plants emit 33 grams CO2 for every kWh generated ... natural gas produces 442 grams CO2 per kWh, power from hard coal 864 grams, and power from lignite, or brown coal, 1034 grams ... nuclear energy accounts for about 117 grams of CO2 per kWh, considering the emissions caused by uranium mining and the construction and operation of nuclear reactors.
118. "About Wind Energy: Factsheets and Statistics". www.pawindenergynow.org. Retrieved 10 May 2017.
119. . Fraunhofer Wind Monitor. Archived from the original on 5 October 2017. Retrieved 14 October 2017.
120. Parisé, J.; Walker, T. R. (2017). "Industrial wind turbine post-construction bird and bat monitoring: A policy framework for Canada". Journal of Environmental Management. 201: 252–259. doi:10.1016/j.jenvman.2017.06.052. PMID 28672197.
121. Hosansky, David (1 April 2011). "Wind Power: Is wind energy good for the environment?". CQ Researcher.
122. "How Harmful is Renewable Energy to Birds? | Article | EESI". www.eesi.org. Retrieved 2 June 2023.
123. "Grid-Scale Storage – Analysis". IEA. Retrieved 2 June 2023.
124. Lewis, Michelle (29 September 2023). "A new wind farm in Kansas trailblazes with light-mitigating technology". Electrek. from the original on 29 September 2023.
125. Reiser, Anya (23 January 2023). "World's Most Powerful Wind Turbine Successfully Produces Power". TOMORROW’S WORLD TODAY®. Retrieved 20 May 2023.
126. "Wind Energy Power Plants in Canada – other provinces". 5 June 2010. Archived from the original on 4 September 2012. Retrieved 24 August 2010.
127. "MBB Messerschmitt Monopteros M50 - 640,00 kW - Wind turbine". en.wind-turbine-models.com.
128. "Ming Yang completes 6.5MW offshore turbine". www.windpowermonthly.com. 1 July 2013. Retrieved 6 June 2023.
129. "When More is More: Multi-Rotor Turbines". www.utmconsultants.com. Retrieved 31 May 2023.
130. "Highest altitude wind generator". Guinness World Records. 19 June 2013. Retrieved 6 June 2023.

Further reading

• Tony Burton, David Sharpe, Nick Jenkins, Ervin Bossanyi: Wind Energy Handbook, John Wiley & Sons, 2nd edition (2011), ISBN 978-0-470-69975-1
• Darrell, Dodge, Early History Through 1875 2 December 2010 at the Wayback Machine, TeloNet Web Development, Copyright 1996–2001
• Robert Gasch, Jochen Twele (ed.), Wind power plants. Fundamentals, design, construction and operation, Springer 2012 ISBN 978-3-642-22937-4.
• Erich Hau, Wind turbines: fundamentals, technologies, application, economics, Springer, 2013 ISBN 978-3-642-27150-2 (preview on Google Books)
• Siegfried Heier, Grid integration of wind energy conversion systems, John Wiley & Sons, 3rd edition (2014), ISBN 978-1-119-96294-6
• Peter Jamieson, Innovation in Wind Turbine Design. Wiley & Sons 2011, ISBN 978-0-470-69981-2
• J. F. Manwell, J. G. McGowan, A. L. Roberts, Wind Energy Explained: Theory, Design and Application, John Wiley & Sons, 2nd edition (2012), ISBN 978-0-47001-500-1
• David Spera (ed,) Wind Turbine Technology: Fundamental Concepts in Wind Turbine Engineering, Second Edition (2009), ASME Press, ISBN 9780791802601
• Alois Schaffarczyk (ed.), Understanding wind power technology, John Wiley & Sons, (2014), ISBN 978-1-118-64751-6
• Hermann-Josef Wagner, Jyotirmay Mathur, Introduction to wind energy systems. Basics, technology and operation. Springer (2013), ISBN 978-3-642-32975-3
• GA Mansoori, N Enayati, LB Agyarko (2016), Energy: Sources, Utilization, Legislation, Sustainability, Illinois as Model State

External links

•   Media related to Wind turbine at Wikimedia Commons
• Global Wind Energy Council
• World's Largest Wind Turbine
• Harvesting the Wind (45 lectures about wind turbines by professor Magdi Ragheb