It provides a cross-disciplinary overview of modern wind turbine technology and an orientation in the associated technical, economic and environmental fields. In its revised third edition, special emphasis has been given to the latest trends in wind turbine technology and design, such as gearless drive train concepts, as well as on new fields of application, in particular the offshore utilisation of wind energy. The author has gained experience over decades designing wind energy converters with a major industrial manufacturer and, more recently, in technical consulting and in the planning of large wind park installations, with special attention to economics. Review Text From the reviews of the third edition: It is a complete yet concise overview and study of the field, its history and all aspects of modern wind turbine technology. Aimed more at scientists and engineers Hau starts with a list of commonly-used symbols and ends with a detailed chapter on the various facets of turbine economics. Real Power, Issue 2, From the reviews of the second edition: "This wide-ranging book, the product of over a quarter century s experience, will be of use to any physicist with an interest in wind power electricity generation.
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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. 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.
This requires them to be stiff, strong, light and resistant to fatigue. New designs Companies seek ways to draw greater efficiency from their designs. A predominant way has been to increase blade length and thus rotor diameter. Retrofitting existing turbines with larger blades reduces the work and risks of redesigning the system.
The current longest blade is Longer blades need to be stiffer to avoid deflection, which requires materials with higher stiffness-to-weight ratio.
Because the blades need to function over a million load cycles over a period of 20—25 years, the fatigue of the blade materials is also critical. Blade materials Materials commonly used in wind turbine blades are described below. Glass and carbon fibers 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 composite material is glass fiber with modified compositions like S-glass, R-glass etc. An ideal candidate for these properties is the spar cap, a structural element of a blade which experiences high tensile loading.
Hybrid reinforcements Instead of making wind turbine blade reinforcements from pure glass or pure carbon, hybrid designs trade weight for cost.
More research is needed about the optimal composition of materials  Nano-engineered polymers and composites Additions of small amount 0. 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.
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. Modern turbines use a couple of tons of copper for generators, cables and such. The current material consumption and stock was compared to input materials for various onshore system sizes. In all EU countries the estimates for doubled the values consumed in These countries would need to expand their resources to meet the estimated demand for 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. It did not consider requirements for small turbines or offshore turbines because those were not common in when the study was done.
Rare metal use would not increase much compared to available supply, however rare 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, square kilometers onshore and 11, 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. Systems that use magnetic direct drive turbines require greater amounts of rare metals. Therefore, an increase in wind turbine manufacture would increase the demand for these resources. By , the demand for Nd is estimated to increase by 4, to 18, tons and for Dy by to tons.
These values are a quarter to half of current production. However, these estimates are very uncertain because technologies are developing rapidly. Its demand has grown due to growth in construction, transportation and wind turbines. 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.
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 send the blade to landfill, to reuse the blade and the composite material elements 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. It pointed out that wind farm waste is less toxic than other garbage. 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, and flaps, and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched.
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  conducted by Charles Meneveau of Johns Hopkins University  and Johan Meyers of Leuven University in Belgium, based on computer simulations  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. 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. An alternative is repowering, where existing wind turbines are replaced with bigger, more powerful ones, sometimes in smaller numbers while keeping or increasing capacity. Demolition 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. In addition, there is currently no competitive market for wind energy, because wind is a freely available natural resource, most of which is untapped.
The energy harvested from the turbine will offset the installation cost, as well as provide virtually free energy for years. 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. Wind farms and nuclear power stations are responsible for between 0. In , for every bird killed by a wind turbine in the US, nearly , were killed by cats and another , by 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. Records This section needs to be updated. Please update this article to reflect recent events or newly available information. December
Erich Hau, Jg. Inhaltsangabe Windmills and Windwheels. Rezensionen From the reviews of the third edition: It is a complete yet concise overview and study of the field, its history and all aspects of modern wind turbine technology. Aimed more at scientists and engineers Hau starts with a list of commonly-used symbols and ends with a detailed chapter on the various facets of turbine economics. Real Power, Issue 2, From the reviews of the second edition: "This wide-ranging book, the product of over a quarter century s experience, will be of use to any physicist with an interest in wind power electricity generation.
Wind Turbines: Fundamentals, Technologies, Application, Economics