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 .
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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.
This must-have second edition includes up-to-date data, diagrams, illustrations and thorough new material on:. Fifty additional homework problems and a new appendix on data processing make this comprehensive edition perfect for engineering students. This book offers a complete examination of one of the most promising sources of renewable energy and is a great introduction to this cross-disciplinary field for practising engineers. He holds an M. His research and graduate student supervision at UMass has produced approximately technical papers in a wide range of energy conversion applications. His recent research interests in wind engineering have been concentrated in the areas of wind system siting, hybrid systems modeling, economics, and offshore wind engineering.
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 ].
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. The conventional drive train consist of a main gearbox and a medium speed PM generator. Series production began end of Largest capacity direct drive The Enercon E with 7. However, the turbine is the world's most powerful onshore-only wind turbine.
The turbine has parted rotor blades with 2 sections for transport. Times Higher Education Supplement , 29 November Please check your email for instructions on resetting your password.
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Skip to Main Content. Wind Energy Explained: Theory, Design and Application Author s: Manwell J. McGowan A. A typical home uses approximately 10, kilowatt-hours kWh , an average of kWh per month.
The manufacturer will also provide information about any maximum wind speeds at which the turbine is designed to operate safely. Most turbines have automatic overspeed-governing systems to keep the rotor from spinning out of control in extremely high winds. Along with information about your local wind resource wind speed and direction and your energy budget, this information will help you decide which size turbine will best meet your electricity needs.
Through the spinning blades, the rotor captures the kinetic energy of the wind and converts it into rotary motion to drive the generator, which produces either AC or wild AC variable frequency, variable voltage , which is typically converted to grid-compatible AC electricity.
Wind Turbine Small wind turbines can be divided into two groups: horizontal axis and vertical axis.
The most commonly used turbine in today's market is the horizontal-axis wind turbine. These turbines typically have two or three blades that are usually made of a composite material such as fiberglass. Vertical-axis wind turbines consist of two types: Savonius and Darrieus.
A Savonius turbine can be recognized by its "S" shaped design when viewed from above. Darrieus turbines look like an eggbeater and have vertical blades that rotate into and out of the wind. The diameter of the rotor defines its "swept area," or the quantity of wind intercepted by the turbine.
The turbine's frame is the structure onto which the rotor, generator, and tail are attached. The tail keeps the turbine facing into the wind. Tower Because wind speeds increase with height, the turbine is mounted on a tower.
In general, the higher the tower, the more power the wind system can produce. The tower also raises the turbine above the air turbulence that can exist close to the ground because of obstructions such as hills, buildings, and trees.
A general rule of thumb is to install a wind turbine on a tower with the bottom of the rotor blades at least 30 feet 9 meters above any obstacle that is within feet 90 meters of the tower. Tilt-down towers provide easy maintenance for turbines. There are two types of towers: self-supporting free-standing and guyed.
Guyed towers, which are the least expensive, can consist of lattice sections, pipe, or tubing depending on the design ; supporting guy wires; and the foundation. They are easier to install than self-supporting towers. However, because the guy radius must be one-half to three-quarters of the tower height, guyed towers require space to accommodate them. Although tilt-down towers are more expensive, they offer the consumer an easy way to perform maintenance on smaller lightweight turbines usually 5 kW or smaller.
Tilt-down towers can also be lowered to the ground during hurricanes and other hazardous weather conditions. Aluminum towers are prone to cracking and should be avoided. Most turbine manufacturers provide wind energy system packages that include a range of tower options. Most manufacturers can provide you with a system package that includes all the parts you need for your application. For example, the parts required for a water-pumping system will be different from the parts required for a residential, grid-connected application.
The balance of system equipment required will also depend on whether the system is grid-connected, stand-alone, or part of a hybrid system.
For a residential grid-connected application, the balance of system parts may include a controller, storage batteries, a power conditioning unit inverter , wiring, foundation, and installation. Many wind turbine controllers, inverters, or other electrical devices may be stamped by a recognized testing agency, such as Underwriters Laboratories or Intertek.
Batteries for Stand-Alone Systems Stand-alone systems systems not connected to the utility grid require batteries to store excess power generated for use when the wind is calm. They also need a charge controller to keep the batteries from overcharging. Automotive batteries are shallow-cycle batteries and should not be used in renewable energy systems because of their short life in deep-cycling operations. In very small systems, DC appliances operate directly off the batteries.
If you want to use standard appliances that use conventional household alternating current AC , you must install an inverter to convert DC electricity from the batteries to AC.
Although the inverter slightly lowers the overall efficiency of the system, it allows the home to be wired for AC, a definite plus with lenders, electrical code officials, and future homedownloaders. For safety, batteries should be isolated from living areas and electronics because they contain corrosive and explosive substances. Lead-acid batteries also require protection from temperature extremes.
Inverters for Grid-Connected Systems In grid-connected systems, the only additional equipment required is a power conditioning unit inverter that makes the turbine output electrically compatible with the utility grid. Batteries are usually not required. What Do Wind Systems Cost? The length of the payback period—the time before the savings resulting from your system equal the cost of the system—depends on the system you choose, the wind resource on your site, electricity costs in your area, and how you use your wind system.
Compare prices when shopping for a wind system as you would any major download by reviewing the product literature from several manufacturers. To justify your investment in a small wind turbine, you will want assurances that your turbine model has been evaluated for safety, performance, and functionality. Photo from Chris Brooks, NREL The Small Wind Certification Council provides independent, accredited certification of small wind turbines and consumer information, and you should familiarize yourself with this material.
The U. Reports from these Regional Test Centers are available for consumers. In addition to requiring certification for small wind turbines, ITAC reviews manufacturers' consumer and dealer services, marketing consistency with third-party testing, turbine operational history, turbine warranty, and manufacturers' response to technical problems, failures, and customer complaints.
As a collaborative and common inventory of turbines, the unified list assures customers that tax- or rate-payer funding fully supports the installation of reliable and safe technology as well as enables improvements in program consistency, transparency, and benefits. Ask for references from past customers with installations similar to the one you are considering.
Ask the system owners about performance, reliability, and maintenance and repair requirements, and whether the system is meeting their expectations.
Also, find out how long the warranty lasts and what it includes. You must decide whether you will perform the installation and maintenance work on your small wind turbine or whether you will hire an experienced small wind installer. This decision will affect your system's cost.
Many people elect to install their own turbines. Before attempting to install your wind turbine, ask yourself the following questions: Can I pour a proper cement foundation? Do I have access to a lift or a way to safely erect the tower? Do I know enough about electricity to safely wire my turbine? Do I know how to safely handle and install batteries? Contact the manufacturer for help or call your state energy office and local utility for a list of local system installers.
A credible installer may be able to provide many services such as permitting, obtaining interconnection approval, etc. Find out if the installer is a licensed electrician.
Ask for references and check them. You may also want to check with the Better Business Bureau. Turbine and tower manufacturers should provide their own operations and maintenance plan; however, turbine owners should be aware that all rotating equipment will require some maintenance. Many turbines require periodic lubrication, oil changes, and replacement of wear surfaces such as brake pads.
The machines should be checked for corrosion and the guy wires for proper tension. In addition, you should check for and replace any worn leading edge tape on the blades, if appropriate. After 10 years, the blades or bearings may need to be replaced, but with proper installation and maintenance, the machine should last 20 years or longer.
Every turbine should include an owner's manual or operations manual to provide the consumer with scheduled and unscheduled maintenance information as well as other unique product information. Scheduled maintenance guidelines should be followed. If you do not have the expertise to maintain the machine, ask whether your installer provides a service and maintenance program.
Notice that the wind speed V has an exponent of 3 applied to it. This means that even a small increase in wind speed results in a large increase in power. That is why a taller tower will increase the productivity of any wind turbine by giving it access to higher wind speeds. So the larger the rotor, the more energy it can capture.
A density correction should be made for higher elevations as shown in the Air Density Change with Elevation graph. A correction for temperature is typically not needed for predicting the long-term performance of a wind turbine. Although the calculation of wind power illustrates important features about wind turbines, the best measure of wind turbine performance is annual energy output.
The difference between power and energy is that power kilowatts [kW] is the rate at which electricity is consumed while energy kilowatt-hours [kWh] is the quantity consumed. They will use a calculation based on the particular wind turbine power curve, the average annual wind speed at your site, the height of the tower that you plan to use, micro-siting characteristics of your site and, if available, the frequency distribution of the wind an estimate of the number of hours that the wind will blow at each speed during an average year.
They should also adjust this calculation for the elevation of your site.
To get a preliminary estimate of the performance of a particular wind turbine, use the formula below. It asks you to provide information about how you will finance the system, the characteristics of your site, and the properties of the system you're considering. It then provides you with a simple payback estimation assumes no increase in electricity rates in years.
If the number of years required to regain your capital investment is greater than or almost equal to the life of the system, then wind energy will not be practical for you.
Is the wind resource at your site good enough to justify your investment in a small wind turbine system? That is a key question and not always easily answered. The wind resource can vary significantly over an area of just a few miles because of local terrain influences on the wind flow.
Yet, there are steps you can take to answer the above question. The highest average wind speeds in the United States are generally found along seacoasts, on ridgelines, and on the Great Plains;  however, many areas have wind resources strong enough to make a small wind turbine project economically feasible.
Although there may be many methodologies for understanding the wind resource at a specific location, gathering on-site, measured wind data is typically preferred. A Pika Energy small wind turbine in Gorham, Maine. Photo from Cultivate Photography Multimedia Design, NREL Prior to conducting an on-site measurement campaign, some small wind project developers use state wind maps to conservatively estimate the wind resource at turbine hub height.
While these maps can provide a general indication of good or poor wind resources, they do not provide a resolution high enough to identify local site features. State wind maps cannot include information on complex terrain, ground cover, wind speed distribution, direction distribution, turbulence intensity, and other local effects.
downloadd maps or services can often provide higher resolution and more flexibility with zooming, orientation, and additional features. Pay attention to a map's height above ground as it relates to the potential project's tower height.
Adjusting the wind speed for the height difference between the map and the turbine height adds a potential source of error depending on the wind shear exponent that is selected, and the greater the height difference the greater the potential error.
Therefore, for small wind generator applications, to m wind maps are far more useful than , , , or m wind maps. It is also important to understand the resolution of the wind map or model-generated data set.
If the resolution is lower than the terrain features, adjustments will be needed to account for local terrain effects. If airport data typically recorded at 30 ft or 10 m above ground or weather station data typically recorded at 5 to 20 ft above ground are used, inquire not only about the site's current equipment and location but also if it is historically consistent with the data collection equipment and siting. Equipment at these sites is not primarily intended for wind resource assessment, so it may not be positioned at an appropriate height or in a location free of obstructions.
Unfortunately, airport and weather stations are usually far from the site of interest, with considerably different orography, tree cover, and monitoring height, making these data of questionable usefulness.
Given the expertise required to effectively establish and correlate wind resource data, the data provided by airport and weather stations may only provide a rough screening assessment. The National Climatic Data Center collects data from airports in the United States and makes wind data summaries available for download. Another useful indirect measurement of the wind resource is the observation of an area's vegetation.
Trees, especially conifers or evergreens, can be permanently deformed by strong winds. This deformity, known as "flagging," has been used to estimate the average wind speed for an area. Flagging, the effect of strong winds on area vegetation, can help determine area wind speeds.
Small wind site assessors can help you determine whether you have a good wind resource on your site. State or utility incentive programs may be able to refer you to site assessors with training in assessing the wind resource at specific sites.
Computer programs that estimate the wind resource at a particular site given specific obstacles are also available. Site assessors and computer programs can help to refine the estimates provided on wind resource maps. On-site data measurement adds a new layer of confidence to the techniques discussed above, but with substantial additional costs, effort, and time, especially when the preferred methodology is to match turbine hub height and collect data for a minimum of 1 year.
Obtaining several years of data is better, or 1 year that can be referenced to a longer-term data set if there is good correlation with the on-site data. A number of small, affordable wind data collection systems are available for on-site measurement and are best run for at least 1 year.
These systems include anemometers, wind vanes, and temperature sensors that are mounted as close to hub height as possible. Calculating the wind shear exponent requires collecting data at two different heights. Having wind shear data is essential for conducting an accurate analysis of the cost versus benefits of taller towers.
In addition, analysis must be performed to determine wind speed averages and extremes, wind distribution, Weibull parameters, the wind direction rose, turbulence intensity, vertical wind shear exponent, and associated uncertainties. The farther you place your wind turbine from obstacles such as buildings or trees, the less turbulence you will encounter.
A proper site assessment is a detailed process that includes wind resource assessment and the evaluation of site characteristics. With this in mind, you may wish to consider hiring an experienced small wind site assessor who can determine your property's optimal turbine location. If the surrounding area of a potential site is not relatively flat for several miles, then an evaluation of the main topographic features is necessary, both nearby macro siting and at the proposed turbine site micro siting.
The topographical evaluation should include shape, height, length, width, and distance and direction away from the proposed turbine site of any landforms. Owners of projects located near complex terrain should take care in selecting the installation site. Landforms or orography can influence wind speed, which affects the amount of electricity that a wind turbine can generate. Elevated areas not only experience increased wind speeds because of their increased height in the wind profile but also may cause local acceleration of the wind speed, depending on the size and shape of the landform.
If you site your wind turbine on the top of or on the windy side of a hill, for example, you will have more access to prevailing winds than in a gully or on the leeward sheltered side of a hill on the same property. Other elevated landforms bluffs, cliffs can create turbulence, including back eddies, as the wind passes up and over them. Siting the tower to avoid the zones of turbulence created by the landform is critical.
Turbulence intensity is a major issue for small turbines because of their tower height and location around "ground clutter. Varied wind resources can exist within the same property.