WIND ENERGY. EXPLAINED. Theory, Design and Application. Second Edition. J. F. Manwell and J. G. McGowan. Department of Mechanical and Industrial. Wind energy's bestselling textbook- fully revised. This must-have second edition includes up-to-date data, diagrams, illustrations and thorough. View Table of Contents for Wind Energy Explained. Wind Energy Explained: Theory, Design and Application. Author(s). J.F. Manwell · J.G.
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Library of Congress Cataloging-in-Publication Data Manwell, J. F. Wind energy explained: theory, design, and application / James Manwell, Jon McGowan. Wind energy explained: Theory, Design, and application [Book Review]. Article ( PDF Available) in IEEE Power and Energy Magazine 1(6) 51 · December with 4, Reads by J.F. Manwell, J.G. McGowan, and. Download as PDF, TXT or read online from Scribd Wind energy explained: theory, design, and application / James Manwell, Jon McGowan, Anthony Rogers .
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.
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. 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 the 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.
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 a hold of wind. However, the energy harvested from the turbine will offset the installation cost, as well as provide virtually free energy for years after.
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 ].
In this study, we propose a method for wind power error estimation based on the wind speed measurement error, probability density function, and wind turbine power curves.
This method uses the actual wind speed data without prior statistical treatment based on 28 wind turbine power curves, which were fitted by Lagrange's method, to calculate the estimate wind power output and the corresponding error propagation.
The proposed error propagation complements the traditional power resource assessments. The wind power estimation error also allows us to estimate intervals for the power production leveled cost or the investment time return.
The implementation of this method increases the reliability of techno-economic resource assessment studies. Introduction Resource assessment is one of the most important steps in any renewable energy project because it can determine the possible power output, thereby contributing to analyses of the techno-economic feasibility of renewable energy use.
Resource assessments are based on weather records and the technical characteristics of the renewable source.
This also applies to wind power as a renewable energy source; therefore, the development of accurate and meticulous methods for measuring and monitoring wind speeds are critical factors in its implementation [ 1 ].
Typical resource assessment methods involve measuring wind speeds at a frequency of 1 or 2 Hz and recording the arithmetic mean every 10 min for at least one year.
These wind speed data are then used to construct a relative frequency distribution, to which a probability density function PDF is fitted. This function and the specific wind turbine power curve WTPC are needed to calculate the amount of available energy and the likely electric power output produced in the specific conditions in a region and with the technology employed [ 2 ].
The analysis of uncertainty plays an important role in the wind power industry because it can elucidate the error and the degree of reliability in a study, e.
During wind turbine power characterization, an extra source of uncertainty is attributable to the statistical process involved in power curve fitting. Given the frequent use of this international standard [ 3 ], several studies have aimed to develop improved statistical techniques, such as those used in power performance tests for small wind turbines SWT and wind power estimation [ 4 — 6 ]. All of these studies recommended techniques for improving the reliability of resource assessments and SWT power performance tests.
Statistical calculus is used widely in wind resource assessments; therefore, it is necessary to reduce the sources of uncertainty to obtain reliable assessments [ 7 ]. A grid connection is not available or can only be made through an expensive extension. You would like to generate clean power.
Glossary of Terms Airfoil—The shape of the blade cross-section, which for most modern horizontal-axis wind turbines is designed to enhance the lift and improve turbine performance.
Alternator—An electric generator for producing alternating current. See also generator. Used to distinguish environmental conditions, e.
Anemometer—A device to measure the wind speed. Authority Having Jurisdiction AHJ —The building authority for the area, generally a city or county building department, including its inspectors. Generally defined as the time in a period when a turbine is able to make power, expressed as a percentage.
Beaufort scale—A scale of wind forces, described by name and range of velocity, and classified from force 0 to 12, with an extension to The initial Francis Beaufort wind force scale of 13 classes 0 to 12 did not reference wind speed numbers but related qualitative wind conditions to effects on the sails of a frigate, then the main ship of the Royal Navy, from "just sufficient to give steerage" to "that which no canvas sails could withstand.
See also net metering. This is the maximum amount of power that can be captured from the wind. In reality, this limit is never achived because of drag, electrical losses, and mechanical inefficiencies. See also Cp. See also wing, airfoil, rotor. Brake—Various systems used to stop the rotor from turning.
Certification—A process by which small wind turbines kW and under can be certified by an independent certification body to meet or exceed the performance and durability requirements of the American Wind Energy Association AWEA Standard. See also Betz limit. Cut-out wind speed—The wind speed at which a wind turbine ceases to generate electricity. Density—Mass per unit of volume. Direct drive—A blade and generator configuration where the blades are connected directly to the electrical generating device so that one revolution of the rotor equates to one revolution of the electrical generating device.
Distributed generation—Energy generation projects where electrical energy is generated primarily for on-site consumption. Term is applied for wind, solar, and non-renewable energy.
It may be useful to average many daily cycles of wind speed or wind energy production to understand a typical daily pattern, by month, season, or year. Downwind—On the opposite side from the direction from which the wind blows. Drag—An aerodynamic force that acts in the direction of the airstream flowing over an airfoil. Electric cost adjustment—An energy charge dollars per kilowatt-hour on a utility bill in addition to the standard rate in the tariff, which is associated with extra costs to download fuel, control emissions, construct transmission upgrades, and so on.
These various costs may be itemized or rolled into one electric cost adjustment rate. Sometimes referred to as fuel cost adjustment. Electric utility company—A company that engages in the generation, transmission, and distribution of electricity for sale, generally in a regulated market.
Electric utilities may be investor owned, publicly owned, cooperatives, or nationalized entities. Energy production—Energy is power exerted over time. Energy production is hence the energy produced in a specific period of time. Electrical energy is generally measured in kilowatt-hours kWh.
See also power. See also temperature, wind, humidity, corrosivity.
Flagging is sometimes used with the Beaufort scale to generate an initial estimate of local site conditions. Note: flagging does not determine the wind resource, but is a confirming indicator of it. For example, sometimes flagging is the result of sunlight availability, or trimming of tree branches near electrical lines.
The assessor needs to understand when flagging is relevant, or when it is a confirming indicator of another condition at the site. Frequency distribution—A statistical function presenting the amount of time at each wind speed level for a given data set and location, usually in percent of time or hours per year.
Furling—A passive protection for the turbine in which the rotor folds up or around the tail vane. Gearbox—A compact, enclosed unit of gears or the like for the purpose of transferring force between machines or mechanisms, often with changes of torque and speed. In wind turbines, gearboxes are used to increase the low rotational speed of the turbine rotor to a higher speed required by many electrical generators.
The mechanical power for an electric generator is usually obtained from a rotating shaft. In a wind turbine, the mechanical power comes from the wind causing the blades on a rotor to rotate. See also blade, rotor, stator, alternator. It may also be used to visualize the relationships between terrain, wind data, land-use boundaries, obstacles, and potential wind turbine locations.
Governor—A device used to limit the RPM of the rotor. Limiting RPM serves to reduce centrifugal forces acting on the wind turbine and rotor as well as limit the electrical output of the generating device. Governors can be electrical, also know as "dynamic braking," or mechanical.
Mechanical governors can be "passive," using springs to pitch the blades out of their ideal orientation, or an offset rotor that pitches out of the wind, or "active" by electrically or hydraulically pitching blades out of their ideal orientation. The network that connects electricity generators to electricity users. Grid-connected—Small wind energy systems that are connected to the electricity distribution system.
These often require a power-conditioning unit that makes the turbine output electrically compatible with the utility grid. See also inverter. Guyline—A guyline or guy wire supports guyed towers, which are the least expensive way to support a wind turbine. Guyed towers can consist of lattice sections, pipe, or tubing. Because the guy radius must be one-half to three-quarters of the tower height, guyed towers require more space to accommodate them than monopole or self-standing lattice towers.
Often called a "propeller-style" wind turbine. See also rotor, blade. Generates electricity by being spun faster than the motor's standard "synchronous" speed. Must be connected to an already-powered circuit to function i. Interconnection standards—Specifies the technical and procedural process by which a customer connects an electricity-generating device to the grid. Such standards include the technical and contractual terms that system owners and utilities must abide by. State public utility commissions typically establish standards for interconnection to the distribution grid, while the Federal Energy Regulatory Commission FERC establishes standards for interconnection to the transmission grid.
While many states have adopted interconnection standards, some states' standards apply only to investor-owned utilities and not to municipal utilities or electric cooperatives. Wind and solar resources are described as intermittent because they change without regard to peoples' needs or wants. Lattice—A structure of crossed wooden or metal strips usually arranged to form a diagonal pattern of open spaces between the strips. Lattice towers, either guyed or freestanding, are often used to support small wind turbines.
Microturbine—A very small wind turbine, usually under a 1, Watt rating, which is appropriate for small energy needs e. Monopole—A freestanding type of tower that is essentially a tube, often tapered. Nacelle—The body of a propeller-type wind turbine, containing the gearbox, generator, blade hub, and other parts. Nameplate capacity—The power capacity of a generating device that is typically affixed to the generating device.
Nameplate capacity typically, but not necessarily, represents the maximum continuous power output of the generating device. A variety of losses may be estimated for obstacle wind shadows, turbulence, turbine wake effects, turbine availability, high-wind hysteresis effects, electrical efficiency, blade icing, blade soiling and surface degradation, idling parasitic losses, control errors, low temperature shutdown, utility system maintenance, and other issues specific to a given turbine installation.
When a customer's generation exceeds the customer's use, electricity from the customer flows back to the grid, offsetting electricity consumed by the customer at a different time during the same billing cycle. In effect, the customer uses excess generation to offset electricity that the customer otherwise would have to download at the utility's full retail rate.
Net metering is required by law in most U. See also behind-the-meter. Sound power is measured in decibels, dB. Building and planning authorities often regulate sound power levels from facilities. See also sound, electrical noise.
Obstruction—A general term for any significant object that would disturb wind flow passing through a turbine rotor. Most common examples are homes, buildings, trees, silos, and fences. Topographical features such as hills or cliffs that might also affect wind flow and are not called obstructions.
Energy produced in these systems is often used for battery charging. Overall height—The total height of a wind turbine from its base at grade to its uppermost extent. See also total height. The definition of peak demand may vary by electric utility. This is a simplified definition of a complex topic. Peak power—The maximum instantaneous power than can be produced by a power-generating system or consumed by a load. Peak power may be significantly higher than average power. During this process, a set of project plans is submitted for review to assure that the project meets local requirements for safety, sound, aesthetics, setbacks, engineering, and completeness.
The permitting agency typically inspects the project at various milestones for adherence to the plans and building safety standards. Power coefficient—The ratio of the power extracted by a wind turbine to the power available in the wind stream.
Power curve—A chart showing a wind turbine's power output across a range of wind speeds. Prevailing wind—The most common direction or directions that the wind comes from at a site.
Prevailing wind usually refers to the amount of time the wind blows from that particular direction but may also refer to the direction the wind with the greatest power density comes from. Rated output capacity—The output power of a wind machine operating at the rated wind speed. Rated wind speed—The lowest wind speed at which the rated output power of a wind turbine is produced.
Reactive power—When the voltage and current waveforms for AC power are out of phase the resulting instantaneous power flow is modeled as real power and reactive power. The presence of reactive power increases the instantaneous current flow required to do work. The increase in current flow results in additional line losses.
The utility tariff for larger customers may include a charge for reactive power compensation, measured in kilo-volt-amp-reactive. Rotor—The rotating part of a wind turbine, including either the blades and blade assembly or the rotating portion of a generator.
Rotor diameter—The diameter of the circle swept by the rotor. Rotor speed—The revolutions per minute of the wind turbine rotor. Setback—In zoning parlance, the distance required between a structure and another structure, property line, utility easement or other demarkation.
Site assessment—The act of evaluating a site to determine a favorable location for a wind turbine, which includes assessing the expected wind resource and potential turbine performance at that location. Small wind turbine—A wind turbine that has a rating of up to kilowatts, and is typically installed near the point of electric usage, such as near homes, businesses, remote villages, and other kinds of buildings.
Sound—Pressure waves occurring at a frequency in the audible range of human hearing that are registered as sensory input by the ear. See also noise. See also Cut-in wind speed. Stator—The stationary part of a rotary machine or device, especially a generator or motor. Most especially related to the collection of stationary parts in its magnetic circuits.
The stator and rotor interact to generate electricity in a generator and to turn the driveshaft in a motor. See also rotor diameter.
Tariff—An official schedule of rates or charges from a utility, usually with different rate schedules by customer classification e. Temperature—A measure of thermal energy. This is typically a design requirement for the turbine. Topography—The surface configuration and relief features of an area, such as hills and bluffs, and the detailed mapping and description thereof. Total height—The height of the wind system from the top of the foundation to which the tower is attached to the tip of a blade extended upwards.
See also overall height. Typical types include monopole, guyed lattice, and self-supporting lattice designs. Turbulence intensity—A basic measure of turbulence that is defined by the ratio of the standard deviation of the wind speed to the mean wind speed.
For wind energy applications this is typically defined as a minute average wind speed and standard deviation based on 1-second samples. Turbulence intensity is important for wind energy applications because it has implications for both power performance and turbine loading.
Experience indicates that it can be a significant issue for small turbines because of their tower height and location around ground clutter, which puts them in the most turbulent area of the atmospheric boundary layer. The effects of turbulence on distributed wind turbines can be seen in both power production and loading Upwind—On the same side as the direction from which the wind is blowing—windward.
Upwind rotor—A horizontal-axis wind turbine whose propeller is located upwind of the tower; a wind turbine with an architecture such that the wind flow passes through the propeller prior to flowing past the tower. A wet stamp implies an original stamped document, not a copy. Also known as a wind power plant. Wind rose—A visual means of representing the frequency with which the wind blows from different directions. Wind shear—The difference in wind speed and direction over a relatively short distance in the atmosphere.
Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across storm fronts and near the coast, and vertical shear seen typically near the surface though also at higher levels in the atmosphere near upper-level jets and frontal zones aloft.