L6 Wind Energy

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Introduction to Wind Energy

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  • Simple, single cell atmospheric convection in a non-rotating Earth.  "Single cell" being either a single cell north or south of the equator.\nTo begin, imagine the earth as a non-rotating sphere with uniform smooth surface characteristics. Assume that the sun heats the equatorial regions much more than the polar regions. In response to this, two huge convection cells develop. An intermediate model: We now allow the earth to rotate.  As expected, air traveling southward from the north pole will be deflected to the right. Air traveling northward from the south pole will be deflected to the left.\nHowever, by looking at the actual winds, even after averaging them over a long period of time, we find that we do not observe this type of motion.  In the 1920’s a new conceptual model was devised that had three cells instead of the single Hadley cell.  These three cells better represent the typical wind flow around the globe.\nRefer to source for this slide and following 3 - http://www.ux1.eiu.edu/~cfjps/1400/circulation.html\n
  • Global winds shape the Earth's climate, determining - in broad strokes - which areas are tropical, desert, or temperate. Here's a simplified overview of how it works.\n\nThe Sun heats the Earth most intensely in the tropical zone around the equator. The heated air rises, cools, and then dumps its moisture as rain. That's why there are rain forests in the tropics.\n\nThe now drier air is forced by the continuously rising equatorial air to move towards the temperate latitudes on either side of the equator. At roughly 30° N and S - called the "horse latitudes" - it can move no further due to the Earth’s rotation, and settles to the surface. \n\nAs the air sinks, it compresses and warms, creating hot, rain-free conditions. \nThis circulation pattern, called a Hadley cell, is why the deserts of the world are located just poleward of the tropics, to the north and south.\n\nSource - http://blogs.edf.org/climate411/2008/01/14/global_winds/\nHorse Latitudes Around 30°N we see a region of subsiding (sinking) air.  Sinking air is typically dry and free of substantial precipitation. Many of the major desert regions of the northern hemisphere are found near 30° latitude.  E.g., Sahara, Middle East, SW United States.\nDoldrums Located near the equator, the doldrums are where the trade winds meet and where the pressure gradient decreases creating very little winds.  That's why sailors find it difficult to cross the equator and why weather systems in the one hemisphere rarely cross into the other hemisphere.  The doldrums are also called the intertropical convergence zone (ITCZ).\n
  • These give rise to and westerlies. Trade winds occur between 0 and 30 degrees latitude, westerlies lie between 30 and 60 degrees - where Ireland lines. \n\nThe trade winds are so named as they carried the Spanish and Portuguese conquerors west to the Americas and they then returned using the westerlies to bring them back east with their heavily laden ships.\n\nCoriolis Force - Once air has been set in motion by the pressure gradient force, it undergoes an apparent deflection from its path, as seen by an observer on the earth. This apparent deflection is called the "Coriolis force" and is a result of the earth's rotation. http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/fw/crls.rxml\n\n
  • Owing to the tilt of the Earth's axis in orbit, the ITCZ will shift north and south.  It will shift to the south in January and north in July.\nThis shift in the wind directions owing to a northward or southward shift in the ITCZ results in the monsoons.  Monsoons are wind systems that exhibit a pronounced seasonal reversal in direction.  The best known monsoon is found in India and southeast Asia.\nWinter -- Flow is predominantly off the continent keeping the continent dry.\nSummer -- Flow is predominantly off the oceans keeping the continent wet.\nMonsoons happen not only in southeast Asia and India, but also in North America.  They are responsible for the increased rainfall in the southwest US during the summer months and the very dry conditions during the winter months.\n\n
  • Owing to the tilt of the Earth's axis in orbit, the ITCZ will shift north and south.  It will shift to the south in January and north in July.\nThis shift in the wind directions owing to a northward or southward shift in the ITCZ results in the monsoons.  Monsoons are wind systems that exhibit a pronounced seasonal reversal in direction.  The best known monsoon is found in India and southeast Asia.\nWinter -- Flow is predominantly off the continent keeping the continent dry.\nSummer -- Flow is predominantly off the oceans keeping the continent wet.\nMonsoons happen not only in southeast Asia and India, but also in North America.  They are responsible for the increased rainfall in the southwest US during the summer months and the very dry conditions during the winter months.\n\n
  • Owing to the tilt of the Earth's axis in orbit, the ITCZ will shift north and south.  It will shift to the south in January and north in July.\nThis shift in the wind directions owing to a northward or southward shift in the ITCZ results in the monsoons.  Monsoons are wind systems that exhibit a pronounced seasonal reversal in direction.  The best known monsoon is found in India and southeast Asia.\nWinter -- Flow is predominantly off the continent keeping the continent dry.\nSummer -- Flow is predominantly off the oceans keeping the continent wet.\nMonsoons happen not only in southeast Asia and India, but also in North America.  They are responsible for the increased rainfall in the southwest US during the summer months and the very dry conditions during the winter months.\n\n
  • Owing to the tilt of the Earth's axis in orbit, the ITCZ will shift north and south.  It will shift to the south in January and north in July.\nThis shift in the wind directions owing to a northward or southward shift in the ITCZ results in the monsoons.  Monsoons are wind systems that exhibit a pronounced seasonal reversal in direction.  The best known monsoon is found in India and southeast Asia.\nWinter -- Flow is predominantly off the continent keeping the continent dry.\nSummer -- Flow is predominantly off the oceans keeping the continent wet.\nMonsoons happen not only in southeast Asia and India, but also in North America.  They are responsible for the increased rainfall in the southwest US during the summer months and the very dry conditions during the winter months.\n\n
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  • The geostrophic winds are largely driven by temperature differences, and thus pressure differences, and are not very much influenced by the surface of the earth. The geostrophic wind is found at altitudes above 1000 metres (3300 ft.) above ground level. \n\nThe geostrophic wind speed may be measured using weather balloons. \n\nLand masses are heated by the sun more quickly than the sea in the daytime. The air rises, flows out to the sea, and creates a low pressure at ground level which attracts the cool air from the sea. This is called a sea breeze. At nightfall there is often a period of calm when land and sea temperatures are equal. At night the wind blows in the opposite direction. The land breeze at night generally has lower wind speeds, because the temperature difference between land and sea is smaller at night. \n\nOne example is the valley wind which originates on south-facing slopes (north-facing in the southern hemisphere). When the slopes and the neighbouring air are heated the density of the air decreases, and the air ascends towards the top following the surface of the slope. At night the wind direction is reversed, and turns into a downslope wind.\n \nIf the valley floor is sloped, the air may move down or up the valley, as a canyon wind. \n\nIf the valley is constricted this can further increase the wind speed.\n\nWinds flowing down the leeward sides of mountains can be quite powerful: Examples are the Foehn in the Alps in Europe, the Chinook in the Rocky Mountains, and the Zonda in the Andes. \nExamples of other local wind systems are the Mistral flowing down the Rhone valley into the Mediterranean Sea, the Scirocco, a southerly wind from Sahara blowing into the Mediterranean sea. \n
  • Interannual –longer than 1 year variations - can have a large effect on the overall performance of a wind farm during its lifetime. Meteorologists reckon it takes 30 years of data to determine long term values and 5 years data is needed to arrive at a reliable wind speed for a site. However 1 years data is sufficient to predict long term seasonal mean wind speeds within 10% and 90% confidence.\nUp to 25% variation can occur in inter annual wind speeds\n\nAnnual Significant variation in seasonal or monthly averaged wind speeds are common thro out the world “march – in like a lion and out like a lamb”... In Ireland the winter is much windier than the summer\n\nDiurnal – daily time scale - sea breezes and valley winds are an example of these . Generally the diurnal variation is much greater in the summer than in the winter – due to solar radiation.\n\nShort term variations include turbulence and gusts, any wind speeds that have a period between less than one second to 10 minutes and have a stochastic nature are considered to be turbulent. A gust is a discrete event within a turbulent air flow, and has measureable characteristics such as amplitude, rise time, max gust variation and lapse time\n
  • Interannual –longer than 1 year variations - can have a large effect on the overall performance of a wind farm during its lifetime. Meteorologists reckon it takes 30 years of data to determine long term values and 5 years data is needed to arrive at a reliable wind speed for a site. However 1 years data is sufficient to predict long term seasonal mean wind speeds within 10% and 90% confidence.\nUp to 25% variation can occur in inter annual wind speeds\n\nAnnual Significant variation in seasonal or monthly averaged wind speeds are common thro out the world “march – in like a lion and out like a lamb”... In Ireland the winter is much windier than the summer\n\nDiurnal – daily time scale - sea breezes and valley winds are an example of these . Generally the diurnal variation is much greater in the summer than in the winter – due to solar radiation.\n\nShort term variations include turbulence and gusts, any wind speeds that have a period between less than one second to 10 minutes and have a stochastic nature are considered to be turbulent. A gust is a discrete event within a turbulent air flow, and has measureable characteristics such as amplitude, rise time, max gust variation and lapse time\n
  • The Griggs-Putnam Index of Deformity is an additional useful tool to help determine the potential of a wind site. The idea is to observe the area’s vegetation. A trees shape, especially conifers or evergreens, in often influenced by winds. \n\nStrong winds can permanently deform the trees. This deformity in trees is known as “flagging”. Flagging is usually more pronounced for single, isolated trees with some height.\n\nThe Griggs-Putnam diagram, like the Wind Resource Maps, can offer a rough estimate of the wind in your area. The more information that you can obtain from the various sources, the greater degree of accuracy you will have in determining your wind speed and your potential power output.\n\nThe Griggs Putnam index should be used with a degree of caution, don’t just depend on one tree, make sure there are several used in the survey. \n\nConifers give better indications that broadleaf trees.\nAbsence of deformation doesn’t necessarily rule a site out of contention \n
  • “Data from the wind monitoring site is essential for determining the viability of the project and, particularly, for assessing financial viability. Problems with the quality of wind data can lead to significant difficulties in obtaining financing. The importance of paying attention to this cannot be over-stated. It is hard to overemphasise how easy it is to acquire bad data. A significant effort is required to ensure good data.” - IWEA best practice guidelines 2008 state:\n\nThe best way of measuring wind speeds at a prospective wind turbine site is to fit an anemometer to the top of a mast which has the same height as the expected hub height of the wind turbine to be used. This way one avoids the uncertainty involved in recalculating the wind speeds to a different height. \n\nBy fitting the anemometer to the top of the mast one minimises the disturbances of airflows from the mast itself. If anemometers are placed on the side of the mast it is essential to place them in the prevailing wind direction in order to minimise the wind shade from the tower. \n\nPlanning and Development Regulations 2008 (S.I. No. 235 of 2008), state that for; The erection of a mast for mapping meteorological conditions.\n1. No such mast shall be erected for a period exceeding 15 months in any 24 month period.\n2. The total mast height shall not exceed 80 metres.\n3. The mast shall be a distance of not less than:\n(a) the total structure height plus:\n(i) 5 metres from any party boundary,\n(ii) 20 metres from any non-electrical overhead cables,\n(iii) 20 metres from any 38kV electricity distribution lines,\n(iv) 30 metres from the centreline of any electricity transmission line of 110kV or more.\n\n(b) 5 kilometres from the nearest airport oraerodrome, or any communication, navigation and surveillance facilities designated by the Irish Aviation Authority, save with the consent in writing of the Authority and compliance with any condition relating to the provision of aviation obstacle warning lighting.\n\n4. Not more than one such mast shall be erected within the site.\n5. All mast components shall have a matt, nonreflective finish and the blade shall be made of material that does not deflect telecommunications signals.\n6. No sign, advertisement or object, not required for the functioning or safety of the mast shall be attached to or exhibited on the mast.\n
  • This formula is a derivative of the kinetic energy formula we looked at in the first lecture, \nK.E. = ½ m v2\n\nAir at 1,500 meters (5000 ft) could be expected to be 15% less dense than normal air\nAir at 30 degrees C would be about 5% less dense than normal air\n\nAir density normally taken to be 1.225 kg/m^3 at 15 deg C and at sea level\nAir density is affected by\nAltitude - Air density decreases as altitude increases\nTemperature - Air density decreases as temperature rises\nHumidity - Air density decreases with increases slightly with increased humidity\n
  • Nothing tells more about a wind turbine’s potential for generating electricity than its swept area. Invariably a turbine with a large rotor will generate more electricity than one with a smaller rotor.\n\nLooking at the example in the first lecture 20 m rotor in 12m/s winds. If we doubled the swept area to 40 meters, there would be a corresponding increase of 4 times the power available from the wind.\n
  • There are additional requirements for overspeed protection, particularly when there is a reduction in the turbines electrical load during operation at high tip speed ratios in high winds. \n\nYaw control is the simplest method of achieving power control, i.e the turbine is turned out of the wind direction and its blades are orientated parallel to the wind. The wind vane located above the nacelle provides wind directional information which forms an input to the control system which in turn rotates the turbine via its yaw control mechanism if necessary. \n\nActive pitch control is more common in variable speed turbines. In this case the the turbine is run at constant speed, however the angel of attack is altered to reduce the lift, thereby altering the lift:drag ratio.\n\nImage source: http://www.popsci.com/content/next-gen-wind-turbine-examined\n
  • There are additional requirements for overspeed protection, particularly when there is a reduction in the turbines electrical load during operation at high tip speed ratios in high winds. \n\nYaw control is the simplest method of achieving power control, i.e the turbine is turned out of the wind direction and its blades are orientated parallel to the wind. The wind vane located above the nacelle provides wind directional information which forms an input to the control system which in turn rotates the turbine via its yaw control mechanism if necessary. \n\nActive pitch control is more common in variable speed turbines. In this case the the turbine is run at constant speed, however the angel of attack is altered to reduce the lift, thereby altering the lift:drag ratio.\n\nImage source: http://www.popsci.com/content/next-gen-wind-turbine-examined\n
  • There are additional requirements for overspeed protection, particularly when there is a reduction in the turbines electrical load during operation at high tip speed ratios in high winds. \n\nYaw control is the simplest method of achieving power control, i.e the turbine is turned out of the wind direction and its blades are orientated parallel to the wind. The wind vane located above the nacelle provides wind directional information which forms an input to the control system which in turn rotates the turbine via its yaw control mechanism if necessary. \n\nActive pitch control is more common in variable speed turbines. In this case the the turbine is run at constant speed, however the angel of attack is altered to reduce the lift, thereby altering the lift:drag ratio.\n\nImage source: http://www.popsci.com/content/next-gen-wind-turbine-examined\n
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  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Site selection for the wind farm requires that accurate wind data over a period of time is available. Experience has shown that an average wind speed > 6 m⋄s-1 indicates a good location. Ideally, mountainous areas (assuming that access is not an issue) and coastal regions are good candidates for locating a wind farm. However, consideration should also be given to losses that may occur in the cabling from wind farm to the electrical grid. \n\nSpacing between wind turbines is a critical issue. Typical spacing should be in the region of 5D → 10D (D being diameter) between each turbine, thereby allowing for the wind to have regained speed and avoid turbulence. Greater turblance intensity reduces the spacing but increases the fatigue loading on the turbines. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
  • Wind turbines and farms can have an adverse impact on the society and the environment. They can spoil areas of natural beauty and affect wildlife. The land area required for wind farms is another concern, however, the land between each turbine can be used of grazing and other farming needs provided access is available and a small exclusion area around the base of the turbine is provided. \n\nThey also can cause electromagnetic interference which affects radar and telecommunications. Noise is another area of concern, however improvements have been made in the blade design to help reduce this. \n\nWhen a turbine has reached its end of service life, it most be disposed of. Established disposal and recycling procedures can be utilised for the metallic parts, however the disposal of the rotor blades consisting of glass reinforced polymers can pose difficulties. \n\nWind turbines reduce CO2 emissions by providing an alternative to fossil fuels. It is also important to stress however that wind turbines do produce CO2, during there manufacture and disposal. Also the construction of turbines in remote regions can affect local communities, the environment, require specialised construction equipment and most also be connected back to the Grid. \n
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  • L6 Wind Energy

    1. 1. ENGINEERING SCIENCE &ENERGY SUSTAINABILITY Lecture 6 - Wind & Wind Energy Keith Vaugh BEng (AERO) MEng
    2. 2. Wind
    3. 3. Wind
    4. 4. Source: Figure 7.5 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001
    5. 5. Source: Figure 7.6 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001
    6. 6. Idealized winds generated by pressure Actual wind patterns owing to land mass gradient and Coriolis Force. distribution..
    7. 7. Idealized winds generated by pressure Actual wind patterns owing to land mass gradient and Coriolis Force. distribution..Source: Figure 7.8 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001
    8. 8. Source: Figure 7.9 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001
    9. 9. Source: Figure 7.9 in The Atmosphere, 8th edition, Lutgens and Tarbuck, 8th edition, 2001
    10. 10. Types of Wind• Geostrophic wind/ Prevailing wind• Storms• Local winds/Sea breezes• Mountain wind/Valley wind Sea and Land Breeze
    11. 11. Wind variation with time• Inter annual• Annual• Diurnal• Short term
    12. 12. Wind Measurement• Wind Atlas/Wind resource maps• Available for Europe and most Western nations• Ireland’s wind atlas developed by SEI
    13. 13. Wind Measurement • Wind Atlas/Wind resource maps • Available for Europe and most Western nations • Ireland’s wind atlas developed by SEISource: European Wind Atlas. Copyright © 1989 by Risø National Laboratory, Roskilde, Denmark.
    14. 14. Anemometers
    15. 15. Power in the wind Lesson Number 1. in an Oklahoma Wind Power Tutorial Series By Tim Hughes, Environmental Verification and Analysis Center, The University of Oklahoma Calculation of Wind Energy and Power Calculating the energy (and later power) available in the wind relies on knowledge of basic geometry and the physics behind kinetic energy. The kinetic energy (KE) of an object (or collection of objects) with total mass M and velocity V is given by the expression: KE = ! * M * V2 (1) 1P = ρ Av 3 Air parcel Now, for purposes of finding the kinetic energy of 2 moving air molecules (i.e.:wind), lets say one has a large air parcel with the shape of a huge hockey puck:ρ = Air density that is, it has the geometry of a collection of air molecules passing though the plane of a wind turbines blades (whichA = Swept area of rotor out a cross-sectional area A), with thickness (D) sweep passing through the plane over a given time. A Air flowv = wind speed The volume (Vol) of this parcel is determined by the parcels area multiplied by its thickness:Therefore, Power availableVol = A * D isProportional to the air density letter rho) represent the density Let ! (the greekProportional to the square ofand is expressed as:diameter the rotor of the air in this parcel. Note that density is mass per volume DProportional to the cube of the wind speed ! = M / Vol and a little algebra gives: M = ! * Vol Now lets consider how the velocity (V) of our air parcel can be expressed. If a time T is required for this parcel (of thickness D) to move through the plane of the wind turbine blades, then the parcels velocity can be expressed as V = D / T, and a little algebra gives D = V * T. Lets make some substitutions in expression no. 1 ( KE = ! * M * V2 ) Substitute for M ( = ! * Vol ) to obtain: KE = ! * (! * Vol) * V2 !
    16. 16. Swept areaIf you double the diameterof a rotor, the swept areais increased by a factor of4A 2.5 MW turbine has arotor diameter ofapproximately 80 m 2Swept area A = π r
    17. 17. }
    18. 18. TYPICAL WIND TURBINE CONFIGURATION }Image source: http://www.popsci.com/content/next-gen-wind-turbine-examined
    19. 19. }
    20. 20. POWER OUTPUT OF A WIND TURBINEThe power in the wind, Pw at a given site } 1 1 3 Pw = ρ Au = ρ A ∫ {u ( z )} p ( u )du 3 2 2where: u(z) = wind speed at hub height p(u) = wind frequency distributionThe average output power Po of a turbine 1 3 Po = η ρ A ∫ CP ( λ ) {u ( z )} p ( u )du 2
    21. 21. }
    22. 22. WIND FARM’sAccurate wind data for a period of time is essential }
    23. 23. WIND FARM’sAccurate wind data for a period of time is essential }
    24. 24. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplains
    25. 25. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplains
    26. 26. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplainsWind turbine spacing should be of the order 5D → 10D
    27. 27. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplainsWind turbine spacing should be of the order 5D → 10D
    28. 28. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplainsWind turbine spacing should be of the order 5D → 10DWind farms will experience array loss, i.e. an array ofturbines will not produce as much power as if they potentiallycould
    29. 29. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplainsWind turbine spacing should be of the order 5D → 10DWind farms will experience array loss, i.e. an array ofturbines will not produce as much power as if they potentiallycould
    30. 30. WIND FARM’sAccurate wind data for a period of time is essential }Mountainous regions and coasts are ideal as well as exposedplainsWind turbine spacing should be of the order 5D → 10DWind farms will experience array loss, i.e. an array ofturbines will not produce as much power as if they potentiallycouldLow wind shear reduces the differential loading on turbineblades, i.e. fatigue loading
    31. 31. }
    32. 32. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian
    33. 33. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian
    34. 34. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise
    35. 35. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise
    36. 36. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise End of Service Life - recyclability
    37. 37. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise End of Service Life - recyclability
    38. 38. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise End of Service Life - recyclability Embodied energy
    39. 39. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise End of Service Life - recyclability Embodied energy
    40. 40. ENVIRONMENTAL IMPACT & PUBLIC ACCEPTANCE } Natural scenery and preservation of wildlife particularly avian Electromagnetic interference and noise End of Service Life - recyclability Embodied energy Remote regions - access and grid connections
    41. 41. Advantages DisadvantagesPrime fuel is free Risk of blade failure (total destruction of installation)Infinitely renewable Suitable small generators not readily availableNon-polluting unsuitable for urban areasIn Ireland the seasonal variation matches Cost of storage battery or mainselectricity demands converter systemBig generators can be located on remote Acoustic noise of gearbox and rotorsites including offshore bladesSaves conventional fuels Construction costs of the supporting tower and access roadsSaves the building of conventional Electromagnetic interference due togeneration blade rotationDiversity in the methods of electricity Environmental objectionsgeneration

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