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Wind Turbine Technology

Tuesday, September 24, 2019Tuesday, September 24, 2019 admin

Materials that are typically used for the rotor blades in wind turbines are composites, as they tend to have a high stiffness, high strength, high fatigue resistance, and low weight. As the price of glass fibers is only about one tenth the price of carbon fiber, glass fiber is still dominant. As competition in the wind market increases, companies are seeking ways to draw greater efficiency from their designs. One of the predominant ways wind turbines have gained performance is by increasing rotor diameters, and thus blade length.

Retrofitting current turbines with larger blades mitigates the need and risks associated with a system-level redesign. As the size of the blade increases, its tendency to deflect also increases. Thus, from a materials perspective, the stiffness-to-weight is of major importance. As the blades need to function over a million load cycles over a period of 20—25 years, the fatigue life of the blade materials is also of utmost importance. By incorporating carbon fiber into parts of existing blade systems, manufacturers may increase the length of the blades without increasing their overall weight.

For instance, the spar cap, a structural element of a turbine blade, commonly experiences high tensile loading, making it an ideal candidate to utilize the enhanced tensile properties of carbon fiber in comparison to glass fiber. A switch to carbon fiber in the structural spar of the blade yields weight savings of 20 to 30 percent, or approximately 15 metric tons. Some of the most common materials which are being used for turbine blades now and will be in the future are summarized below:. 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. This increases the stiffness, tensile and compression strength. A promising source of the composite materials in the future is glass fibers with modified compositions like S-glass, R-glass etc. The world currently longest wind turbine rotor blade, the However, additional investigations are required for the optimal composition of the materials [50].

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Additions of small amount 0. Utilizing carbon fiber enables for simpler designs that use less raw material. The chief manufacturing process in blade fabrication is the layering of plies. By reducing the number of layers of plies, as is enabled by thinner blade design, the cost of labor may be decreased, and in some cases, equate to the cost of labor for glass fiber blades. Materials for wind turbine parts other than the rotor blades including the rotor hub, gearbox, frame, and tower are largely composed of steel.

Modern turbines use a couple of tons of copper for generators, cables, and such. Prestressed 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, increasing the demand for magnetic materials in wind turbines.

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 a thermosetting matrix and glass fibers or a combination of glass and carbon fibers. Thermosetting matrix cannot be remolded to form new composites. So the options are either to reuse the blade and the composite material elements as they are found in the blade or to transform the composite material into a new source of material.

In Germany, wind turbine blades are commercially recycled as part of an alternative fuel mix for a cement factory. A 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 current material consumption and stock was compared to input materials for various onshore system sizes. In all EU countries the estimates for exceeded and doubled the values consumed in These countries would need to expand their resources to be able to meet the estimated demand for Globally, the main exporting countries are South Africa, Mexico and China.

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This is similar with other critical and valuable materials required for energy systems such as magnesium, silver and indium. In addition, the levels of recycling of these materials is very low and focusing on that could alleviate issues with supply in the future. It is important to note that since most of these valuable materials are also used in other emerging technologies, like LEDs , PVs and LCDs , it is projected that demand for them will continue to increase. They did not address requirements for small turbines or offshore turbines since those were not widely deployed in , when the study was created.

They did not see a high increase in demand for rare metals compared to available supply, however rare metals that are also being used for other technologies such as batteries which are increasing its global demand need to be taken into account. Land, whbich might not be considered a material, is an important resource in deploying wind technologies. Reaching the goal would require 50, square kilometers of onshore land area and 11, square kilometers of offshore. This is not considered a problem in the US due to its vast area and the ability to use land for farming and grazing.

A greater limitation for the technology would be the variability and transmission infrastructure to areas of higher demand. Permanent magnets for wind turbine generators contain rare earth metals such as Nd , Pr , Tb , and Dy. Systems that use magnetic direct drive turbines require higher amounts of rare metals. Therefore, an increase in wind production would increase the demand for these resources.

It is estimated that the additional demand for Nd in may be 4, to 18, tons and Dy could see an increase of to tons. These values represent a quarter to half of current production levels. However, since technologies are developing rapidly, driven by supply and price of materials these estimated levels are extremely uncertain. Since it is the most widely used material for reinforcement in composites around the globe, the expansion of end use applications such as construction, transportation and wind turbines has fueled its popularity.

Concerns about wind turbines

However China is currently the largest producer. The industry receives subsidies from the Chinese government allowing them to export it cheaper to the US and Europe. However, due to the higher demand in the near future some price wars have started to developed to implement anti dumping strategies such as tariffs on Chinese glass fiber. 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.

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.

Larger, more costly turbines generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched. 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 [62] conducted by Charles Meneveau of the Johns Hopkins University, [63] and Johan Meyers of Leuven University in Belgium, based on computer simulations [64] 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.

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. 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.

Older turbines were in some early cases not required to be removed when reaching the end of their life. Some still stand, waiting to be recycled or repowered. A demolition industry develops to recycle offshore turbines at a cost of DKK 2—4 million per MW , to be guaranteed by the owner. Wind turbines are generally inexpensive. They will produce electricity at between two and six cents per kilowatt hour, which is one of the lowest-priced renewable energy sources. In addition, there is no competitive market for wind energy, as it does not cost money to get ahold of wind.

However, the energy harvested from the turbine will offset the installation cost, as well as provide virtually free energy for years after. Wind turbines provide a clean energy source, emitting no greenhouse gases and no waste product. Over 1, 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. Environmental impact of wind power includes effect on wildlife, but can be mitigated if proper monitoring and mitigation strategies are implemented.

For every bird killed by a wind turbine in the US, nearly , are killed by each of feral cats and buildings. Further, marine life is affected by water intakes of steam turbine cooling towers heat exchangers for nuclear and fossil fuel generators, by coal dust deposits in marine ecosystems e. Energy harnessed by wind turbines is intermittent, 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. However, it can form part of the energy mix , which also includes power from other sources. Notably, the relative available output from wind and solar sources is often inversely proportional balancing [ citation needed ].

Technology is also being developed to store excess energy, which can then make up for any deficits in supplies. From Wikipedia, the free encyclopedia. This article is about wind-powered electrical generators. For wind-powered machinery used to grind grain or pump water, see Windmill and Windpump. History of wind power.

Wind turbines on public display. This section needs to be updated. Please update this article to reflect recent events or newly available information. Renewable energy portal Sustainable development portal. Renewable and Sustainable Energy Reviews. An illustrated history , p.

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Wind energy in the 21st century: Oxford Dictionary of National Biography online ed. Subscription or UK public library membership required. Danish Wind Industry Association. Archived from the original on 8 September Retrieved 28 December Archived from the original on 3 February Orkney Sustainable Energy Website. Orkney Sustainable Energy Ltd. Retrieved 19 December Retrieved 6 November Bureau of Land Management. Retrieved 23 April Archived from the original PDF on 16 May Retrieved 2 November Journal of Solar Energy Engineering.

Fundamentals, Technologies, Application, Economics. American Wind Energy Association. Archived from the original on 23 September Retrieved 24 September Archived from the original on 7 June National Renewable Energy Laboratory. Great In , Also-rans In ".

Archived from the original on Archived from the original on 3 April Retrieved 25 April For example, much controversy surrounded the turbine, megawatt Cape Wind project off the coast of Massachusetts , which was approved for development in April after an eight-year federal review. Located in Nantucket Sound, the project drew opposition centred on potential negative aesthetic effects the wind farm might have on scenic vistas within range of tourist destinations and second homes along Cape Cod.

Wind turbines have also been associated with killing birds at notable wind farm locations such as Altamont Pass, California. However, it is estimated that one or two birds per turbine per year are killed by wind turbines, with the majority of turbines having no impact at all. However, a much higher number of bats were reported to have been killed by wind turbines. While the exact cause of those fatalities is unknown, the migration and mating behaviour of migratory tree bats is widely discussed and is currently being researched by biologists. We welcome suggested improvements to any of our articles.

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