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Encyclopedia > Wind power
An example of a wind turbine. This 3 bladed turbine is the most common design of modern wind turbines.

Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity to rural residences or grid-isolated locations. Wind turbines in Neuenkirchen, Dithmarschen (Germany). ...

Wind energy is plentiful, renewable, widely distributed, clean, and reduces toxic atmospheric and greenhouse gas emissions if used to replace fossil-fuel-derived electricity. The intermittency of wind seldom creates problems when using wind power at low to moderate penetration levels.[4] Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Intermittent power sources are sources of power generation, primarily electricity, whose power output is either variable or intermittent. ...

For more details on this topic, see Wind.

There is an estimated 50 to 100 times more wind energy than plant biomass energy available on Earth.[5][6] Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) occur. Eventually, the wind energy is converted through friction into diffuse heat throughout the Earth's surface and the atmosphere. For other uses, see Wind (disambiguation). ...

The origin of wind is complex. The Earth is unevenly heated by the sun resulting in the poles receiving less energy from the sun than the equator does. Also the dry land heats up (and cools down) more quickly than the seas do. The differential heating drives a global atmospheric convection system reaching from the Earth's surface to the stratosphere which acts as a virtual ceiling. World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses IlhÃ©u das Rolas, in SÃ£o TomÃ© and PrÃ­ncipe. ... Convection in the most general terms refers to the movement of currents within fluids (i. ... Atmosphere diagram showing stratosphere. ...

### Wind variability and turbine power

The power in the wind can be extracted by allowing it to blow past moving wings that exert torque on a rotor. The amount of power transferred is directly proportional to the density of the air, the area swept out by the rotor, and the cube of the wind speed. A Darrieus wind turbine once used for electric power generation in the Magdalen Islands. ... A Darrieus wind turbine once used for electric power generation in the Magdalen Islands. ... Fig. ... Torque applied via an adjustable end wrench Relationship between force, torque, and momentum vectors in a rotating system In physics, torque (or often called a moment) can informally be thought of as rotational force or angular force which causes a change in rotational motion. ... In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. ...

The power P available in the wind is given by:

$P = begin{matrix}frac{1}{2}end{matrix}alpharhopi r^2 v^3$,

where P = power in watts, alpha = efficiency constant, rho = mass density of air in kilograms per cubic meter, r = radius of the wind turbine in meters, and v = velocity of the air in meters per second. In physics and engineering, including mechanical and electrical engineering, energy efficiency is a dimensionless number, with a value between 0 and 1 or, when multiplied by 100, is given as a percentage. ...

The mass flow of air that travels through the swept area of a wind turbine varies with the wind speed and air density. As an example, on a cool 15 °C (59 °F) day at sea level, air density is 1.225 kilograms per cubic metre. An 8 m/s breeze blowing through a 100 meter diameter rotor would move almost 77,000 kilograms of air per second through the swept area. Mass flow rate is the movement of mass per time. ...

The kinetic energy of a given mass varies with the square of its velocity. Because the mass flow increases linearly with the wind speed, the wind power available to a wind turbine increases as the cube of the wind speed. The power of the example breeze above through the example rotor would be about 2.5 megawatts. The cars of a roller coaster reach their maximum kinetic energy when at the bottom of their path. ...

As the wind turbine extracts energy from the air flow, the air is slowed down, which causes it to spread out and diverts it around the wind turbine to some extent. Albert Betz, a German physicist, determined in 1919 (see Betz' law) that a wind turbine can extract at most 59% of the energy that would otherwise flow through the turbine's cross section. The Betz limit applies regardless of the design of the turbine. Albert Betz (25 December 1885 - 16 April 1968) was a German Engineer and a pioneer of wind energy technology. ... Betz law reflects a theory for flow machines, developed by Albert Betz. ...

Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. Energy is the Betz limit through a 100 meter diameter circle facing directly into the wind. Total energy for the year through that circle was 15.4 gigawatt-hours.

Windiness varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there. To assess the climatology of wind speeds at a particular location, a probability distribution function is often fit to the observed data. Different locations will have different wind speed distributions. The distribution model most frequently used to model wind speed climatology is a two-parameter Weibull distribution because it is able to conform to a wide variety of distribution shapes, from Gaussian to exponential. The Rayleigh model, an example of which is shown plotted against an actual measured dataset, is a specific form of the Weibull function in which the shape parameter equals 2, and very closely mirrors the actual distribution of hourly wind speeds at many locations. Plot of wind speeds measured in 2002 at the Lee Ranch facility. ... Plot of wind speeds measured in 2002 at the Lee Ranch facility. ... The kilowatt-hour (symbol: kWÂ·h) is a unit for measuring energy. ... In probability theory and statistics, the Weibull distribution (named after Waloddi Weibull) is a continuous probability distribution with the probability density function where and is the shape parameter and is the scale parameter of the distribution. ... In probability theory and statistics, the Rayleigh distribution is a continuous probability distribution. ...

Worldwide installed capacity and prediction 1997-2010, Source: WWEA

Because so much power is generated by higher windspeed, much of the average power available to a windmill comes in short bursts. The 2002 Lee Ranch sample is telling; half of the energy available arrived in just 15% of the operating time. The consequence is that wind energy does not have as consistent an output as fuel-fired power plants; utilities that use wind power must provide backup generation or grid power reception capability for times that the wind is weak. Image File history File links Wind_2006andprediction_en. ... Image File history File links Wind_2006andprediction_en. ...

Since wind speed is not constant, a wind generator's annual energy production is never as much as its nameplate rating multiplied by the total hours in a year. The ratio of actual productivity in a year to this theoretical maximum is called the capacity factor. A well-sited wind generator will have a capacity factor of about 35%. This compares to a typical capacity factors of 90% for nuclear plants (like wind farms, they have negligible fuel cost, and are therefore often run at maximum capacity with the load following relegated to other plants).[7] The lower values of 70% for coal plants and 30% for oil plants reflect a throttling-back of plants with high cost fuel in times of low demand. The capacity factor of a power plant is the amount of electricity that it produces over a period of time, divided by the amount of electricity it could have produced if it had run at full power over that time period. ...

When comparing the size of wind turbine plants to fueled power plants, it is important to note that 1000 kW of wind-turbine potential power would be expected to produce as much energy in a year as approximately 500 kW of coal-fired generation. Though the short-term (hours or days) output of a wind-plant is not completely predictable, the annual output of energy tends to vary only a few percent points between years. A power station (also power plant) is a facility for the generation of electric power. ...

When storage, such as with pumped hydroelectric storage, or other forms of generation are used to "shape" wind power (by assuring constant delivery reliability), commercial delivery represents a cost increase of about 25%, yielding viable commercial performance.[8] Electricity consumption can be adapted to production variability to some extent with Energy Demand Management and smart meters that offer variable market pricing over the course of the day. For example, municipal water pumps that feed a water tower do not need to operate continuously and can be restricted to times when electricity is plentiful and cheap. Consumers could choose when to run the dishwasher or charge an electric vehicle, making it very convenient. Electric and plug-in hybrid vehicles also offer a significant demand management tool and could potentially be set to charge automatically during periods of excess wind output. Alternately, charging could be scheduled for the late evening and early morning hours when there will likely be excess generation capacity. Pumped storage hydroelectricity is a method of storing and producing electricity to supply high peak demands by moving water between reservoirs at different elevations. ... Energy demand management is also known as demand side management (DSM). ... A Smart meter generally refers to a type of advanced meter (usually an electrical meter) that identifies consumption in more detail than a conventional meter, and optionally communicates that information via some network back to the local utility for monitoring and billing purposes. ...

How Does Wind Energy Work?

1. The wind blows on the blades and makes them turn.

2. The blades turn a shaft inside the nacelle (the box at the top of the turbine).

3. The shaft goes into a gearbox which increases the rotation speed enough for

4. the generator, which uses magnetic fields to convert the rotational energy into electrical energy. These are similar to those found in normal power stations.

5. The power output goes to a transformer, which converts the electricity coming out of the generator at around 700 Volts (V) to the right voltage for distribution system, typically 33,000 V.

6. The national grid transmits the power around the country.

## Turbine placement

Map of available wind power over the United States. Color codes indicate wind power density class.

As a general rule, wind generators are practical where the average wind speed is 10 mph (16 km/h or 4.5 m/s) or greater. Usually sites are pre-selected on basis of a wind atlas, and validated with wind measurements. Meteorology plays an important part in determining possible locations for wind parks but meteorological wind data alone is usually not sufficient for accurate siting of a large wind power project. Site Specific Meteorological Data is crucial to determining site potential. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year with a minimum likelihood of sudden powerful bursts of wind. A vitally important factor of turbine siting is also access to local demand or transmission capacity. Image File history File links Download high-resolution version (1130x713, 162 KB) Description: U.S. wind power map. ... Image File history File links Download high-resolution version (1130x713, 162 KB) Description: U.S. wind power map. ... A wind atlas contains data on the wind speed and wind direction in a region. ... // Meteorology (from Greek: Î¼ÎµÏ„Î­Ï‰ÏÎ¿Î½, meteoron, high in the sky; and Î»ÏŒÎ³Î¿Ï‚, logos, knowledge) is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. ... Power line redirects here. ...

The most crucial step in the development of a potential wind site is the collection of accurate and verifiable wind speed and direction data as well as other site parameters.[9] To collect wind data a Meteorological Tower is installed at the potential site with instrumentation installed at various heights along the tower. All towers include anemometers to determine the wind speed and wind vanes to determine the direction. The towers generally vary in height from 30 to 60 meters. The towers primarily used in determining site feasibility for potential wind farms are guyed steel-pipe structures which are left to collect data for one to two years and then usually disassembled. Data is collected by a data logging device which stores and transmits data to a server where it is analyzed.

The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and lower air viscosity. The increase in velocity with altitude is most dramatic near the surface and is affected by topography, surface roughness, and upwind obstacles such as trees or buildings. Typically, the increase of wind speeds with increasing height follows a logarithmic profile that can be reasonably approximated by the wind profile power law, using an exponent of 1/7th, which predicts that wind speed rises proportionally to the seventh root of altitude. Doubling the altitude of a turbine, then, increases the expected wind speeds by 10% and the expected power by 34% (calculation: increase in power = (2.0) ^(3/7) – 1 = 34%). The Wind Profile Power Law is an empirical relationship between the wind speeds at one height, and those at another. ...

Wind farms or wind parks often have many turbines installed. Since each turbine extracts some of the energy of the wind, it is important to provide adequate spacing between turbines to avoid excess energy loss. Where land area is sufficient, turbines are spaced three to five rotor diameters apart perpendicular to the prevailing wind, and five to ten rotor diameters apart in the direction of the prevailing wind, to minimize efficiency loss. The "wind park effect" loss can be as low as 2% of the combined nameplate rating of the turbines.

Utility-scale wind turbine generators have minimum temperature operating limits which restrict the application in areas that routinely experience temperatures less than −20 °C. Wind turbines must be protected from ice accumulation, which can make anemometer readings inaccurate and which can cause high structure loads and damage. Some turbine manufacturers offer low-temperature packages at a few percent extra cost, which include internal heaters, different lubricants, and different alloys for structural elements, to make it possible to operate the turbines at lower temperatures. If the low-temperature interval is combined with a low-wind condition, the wind turbine will require station service power, equivalent to a few percent of its output rating, to maintain internal temperatures during the cold snap. For example, the St. Leon, Manitoba project has a total rating of 99 MW and is estimated to need up to 3 MW (around 3% of capacity) of station service power a few days a year for temperatures down to −30 °C. This factor affects the economics of wind turbine operation in cold climates.[citation needed] A hemispherical cup anemometer of the type invented in 2000 by John Thomas Romney Robinson An anemometer is a device for measuring the velocity or the pressure of the wind, and is one instrument used in a weather station. ... St. ... Motto: Gloriosus et Liber (Latin: Glorious and free) Capital Winnipeg Largest city Winnipeg Official languages English French (de facto) Government Lieutenant-Governor John Harvard Premier Gary Doer (NDP) Federal representation in Canadian Parliament House seats 14 Senate seats 6 Confederation July 15, 1870 (5th) Area  Ranked 8th Total 647,797...

### Onshore

Onshore turbine installations in hilly or mountainous regions tend to be on ridgelines generally three kilometers or more inland from the nearest shoreline. This is done to exploit the so-called topographic acceleration. The hill or ridge causes the wind to accelerate as it is forced over it. The additional wind speeds gained in this way make large differences to the amount of energy that is produced. Great attention must be paid to the exact positions of the turbines (a process known as micro-siting) because a difference of 30m can sometimes mean a doubling in output. Local winds are often monitored for a year or more with anemometers and detailed wind maps constructed before wind generators are installed. Anemometer installation on roof of Deconism Gallery, using three size 6, schedule 40 pipes in their original uncut 20 foot (6 m) lengths. ...

For smaller installations where such data collection is too expensive or time consuming, the normal way of prospecting for wind-power sites is to directly look for trees or vegetation that are permanently "cast" or deformed by the prevailing winds. Another way is to use a wind-speed survey map, or historical data from a nearby meteorological station, although these methods are less reliable. Prospecting is the physical search for minerals, fossils, precious metals or mineral specimens, and is also known as fossicking. ...

Wind farm siting can sometimes be highly controversial, particularly as the hilltop, often coastal sites preferred are often picturesque and environmentally sensitive (for instance, having substantial bird life).

### Near-Shore

Near-Shore turbine installations are generally considered to be inside a zone that is on land within three kilometers of a shoreline or on water within ten kilometers of land. These areas tend to be windy and are good sites for turbine installation, because a primary source of wind is convection caused by the differential heating and cooling of land and sea over the cycle of day and night. Wind speeds in these zones share the characteristics of both onshore and offshore wind, depending on the prevailing wind direction.

Common issues that are shared within near-shore wind development zones are aviary (including bird migration and nesting), aquatic habitat, transportation (including shipping and boating) and visual aesthetics. Local residents in some potential sites have strongly opposed the installation of wind farms due to these concerns. The Parthenons facade showing an interpretation of golden rectangles in its proportions. ...

### Offshore

Offshore wind turbines near Copenhagen

Offshore wind development zones are generally considered to be ten kilometers or more from land. Offshore wind turbines are less obtrusive than turbines on land, as their apparent size and noise can be mitigated by distance. Because water has less surface roughness than land (especially deeper water), the average wind speed is usually considerably higher over open water. Capacity factors (utilisation rates) are considerably higher than for onshore and near-shore locations which allows offshore turbines to use shorter towers, making them less visible. Download high resolution version (1024x357, 49 KB)Danish wind turbines near Copenhagen. ... Download high resolution version (1024x357, 49 KB)Danish wind turbines near Copenhagen. ... For other uses, see Copenhagen (disambiguation). ...

In stormy areas with extended shallow continental shelves (such as Denmark), turbines are practical to install — Denmark's wind generation provides about 18% of total electricity production in the country, with many offshore windfarms. Denmark plans to increase wind energy's contribution to as much as half of its electrical supply.

Locations have begun to be developed in the Great Lakes - with one project by Trillium Power approximately 20 km from shore and over 700 MW in size. Ontario, Canada is aggressively pursuing wind power development and has many onshore wind farms and several proposed near-shore locations but presently only one offshore development in fresh water and one on the Pacific west coast.

In most cases offshore environment is more expensive than onshore but this depends on the unique attributes of the specific site. Offshore towers are generally taller than onshore towers once the submerged height is included, and offshore foundations may be more difficult to build and more expensive but again this will be determined by the specific site of the proposed development. Power transmission from offshore turbines is generally through undersea cable, which is more expensive to install than cables on land, and may use high voltage direct current operation if significant distance is to be covered — which then requires yet more equipment. Offshore saltwater environments can also raise maintenance costs by corroding the towers, but fresh-water locations such as the Great Lakes do not. Repairs and maintenance are usually more difficult or slower, and generally more costly, than on onshore turbines due to the location of the offshore site. These costs may vary greatly depending on the exact site of the offshore development. Offshore saltwater wind turbines are outfitted with extensive corrosion protection measures like coatings and cathodic protection, which may not be required in fresh water locations. A submarine communications cable is a cable laid beneath the sea to carry telecommunications between countries. ... HVDC or high-voltage, direct current electric power transmission systems contrast with the more common alternating-current systems as a means for the bulk transmission of electrical power. ... Aluminium anodes mounted on a steel jacket structure Cathodic protection (CP) is a technique to control the corrosion of a metal surface by making that surface the cathode of an electrochemical cell. ...

While there is a significant market for small land-based windmills, offshore wind turbines have recently been and will probably continue to be the largest wind turbines in operation, because larger turbines allow for the spread of the high fixed costs involved in offshore operation over a greater quantity of generation, reducing the average cost. For similar reasons, offshore wind farms tend to be quite large—often involving over 100 turbines—as opposed to onshore wind farms which can operate competitively even with much smaller installations. Fixed costs are un-expired assets or expenses whose total does not change in proportion to the activity of a business, within the relevant time period or scale of production. ... Marginal cost is a term in economics. ... A wind farm is a collection of wind turbines in the same location. ...

### Airborne

Main article: Airborne wind turbine

Wind turbines might also be flown in high speed winds at altitude,[10] although no such systems currently exist in the marketplace. An Ontario (Canada) company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium[11] An airborne wind turbine is a design concept for a wind turbine that is supported in the air without a tower. ...

The Italian project called "Kitegen" uses a prototype vertical-axis wind turbine. It is an innovative plan (still in the construction phase) that consists of one wind farm with a vertical spin axis, and employs kites to exploit high-altitude winds. The Kite Wind Generator (KWG) or KiteGen is claimed to eliminate all the static and dynamic problems that prevent the increase of the power (in terms of dimensions) obtainable from the traditional horizontal-axis wind turbine generators. A number of other designs for vertical-axis turbines have been developed or proposed, including small scale commercial or pilot installations. However, vertical-axis turbines remain a commercially unproven technology.

## Utilization

Main article: :Category:Wind power by country

### Large scale

Installed windpower capacity (MW)[12][13]
Rank Nation 2005 2006 Latest
1 Germany 18,415 20,622 21,283
2 Spain 10,028 11,615 12,801
3 United States 9,149 11,603 13,885
4 India 4,430 6,270 7,231
5 Denmark (& Færoe Islands) 3,136 3,140
6 China 1,260 2,604 2,956
7 Italy 1,718 2,123
8 United Kingdom 1,332 1,963 2,293
9 Portugal 1,022 1,716 1,874
11 France 757 1,567 2,100
12 Netherlands 1,219 1,560
13 Japan 1,061 1,394
14 Austria 819 965
15 Australia 708 817
16 Greece 573 746 804
17 Ireland 496 745 866
18 Sweden 510 572
19 Norway 267 314
20 Brazil 29 237
21 Egypt 145 230 580
22 Belgium 167 193
23 Taiwan 104 188
24 South Korea 98 173
25 New Zealand 169 171 322
26 Poland 83 153 216
27 Morocco 64 124
28 Mexico 3 88
29 Finland 82 86 107
30 Ukraine 77 86
31 Costa Rica 71 74
32 Hungary 18 61
33 Lithuania 6 55
34 Turkey 20 51
35 Czech Republic 28 50
36 Iran 23 48
Rest of Europe 129 163
Rest of Americas 109 109
Rest of Asia 38 38
Rest of Africa & Middle East 31 31
Rest of Oceania 12 12
World total (MW) 59,091 74,223 79,341

There are many thousands of wind turbines operating, with a total capacity of 73,904 MW of which Europe accounts for 65% (2006). The average output of one megawatt of wind power is equivalent to the average electricity consumption of about 250 American households. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and world wind generation capacity more than quadrupled between 2000 and 2006 and in some countries (Spain and Denmark) wind can supply 10% or more of the nation´s electricity. 81% of wind power installations are in the US and Europe, but the share of the top five countries in terms of new installations fell from 71% in 2004 to 55% in 2005. Offshore wind turbines near Copenhagen Some 20 per cent of Danish domestic electricity comes from wind [1]and Denmark is a leading wind power nation in the world. ...

By 2010, the World Wind Energy Association expects 160GW of capacity to be installed worldwide[1], up from 73.9GW at the end of 2006, implying an anticipated net growth rate of more than 21% per year.

Germany, Spain, the United States, India, and Denmark have made the largest investments in wind generated electricity. Denmark is prominent in the manufacturing and use of wind turbines, with a commitment made in the 1970s to eventually produce half of the country's power by wind. Denmark generates over 20% of its electricity with wind turbines, the highest percentage of any country and is fifth in the world in total wind power generation (which can be compared with the fact that Denmark is 56th on the general electricity consumption list). Denmark and Germany are leading exporters of large (0.66 to 5 MW) turbines. Countries by electricity consumption This is a list of countries by electricity consumption mostly based on The World Factbook [1] accessed in March 2006. ...

Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 28% of the total world capacity in 2006 (7.3% of German electricity); the official target is that by 2010, renewable energy will meet 12.5% of German electricity needs — it can be expected that this target will be reached even earlier. Germany has 18,600 wind turbines, mostly in the north of the country — including three of the biggest in the world, constructed by the companies Enercon (6 MW), Multibrid (5 MW) and Repower (5 MW). Germany's Schleswig-Holstein province generates 36% of its power with wind turbines. Enercon E-112 Enercon GmbH, based in Aurich, Northern Germany, is the third-largest wind turbine manufacturer in the world and the market leader in Germany. ... Schleswig-Holstein is the northernmost of the 16 Bundesländer in Germany. ...

Spain and the United States, this last with bigger population, are next in terms of installed capacity.

In 2005, the government of Spain approved a new national goal for installed wind power capacity of 20,000 MW by 2012. According to trade journal Windpower Monthly; however, in 2006 they abruptly halted subsidies and price supports for wind power. According to the American Wind Energy Association, wind generated enough electricity to power 0.4% (1.6 million households) of total electricity in US, up from less than 0.1% in 1999. In 2005, both Germany and Spain have produced more electricity from wind power than from hydropower plants. US Department of Energy studies have concluded wind harvested in just three of the fifty U.S. states could provide enough electricity to power the entire nation, and that offshore wind farms could do the same job.[12] Undershot water wheels on the Orontes River in Hama, Syria Saint Anthony Falls Hydropower is the capture of the energy of moving water for some useful purpose. ... The United States Department of Energy (DOE) is a Cabinet-level department of the United States government responsible for energy policy and nuclear safety. ...

In recent years, the United States has added more wind energy to its grid than any other single country, and capacity is expected to grow by 3 gigawatts (3,000 megawatts) in 2007. Texas has become the leader in Wind Energy production, far surpassing California. In 2007, the state expects to add 2 gigawatts to raise its existing capacity to approximately 4.5 gigawatts. Iowa and Minnesota are expected to reach the 1 gigawatt mark by the end of 2007.[14] Wind power generation in the U.S. was up 31.8% in February, 2007 from February, 2006.[15] Official language(s) English Capital Sacramento Largest city Los Angeles Largest metro area Greater Los Angeles Area  Ranked 3rd  - Total 158,302 sq mi (410,000 kmÂ²)  - Width 250 miles (400 km)  - Length 770 miles (1,240 km)  - % water 4. ...

India ranks 4th in the world with a total wind power capacity of 6,270 MW in 2006. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 has given additional impetus to the Indian wind industry.[1] The windfarm near Muppandal, Tamil Nadu, India, provides an impoverished village with energy for work.[16][17] India-based Suzlon Energy is one of the world's largest wind turbine manufacturers.[18] Muppandal (Tamil: à®®à¯à®ªà¯à®ªà®¨à¯à®¤à®²à¯)is a small village on the southern tip of India in Kanyakumari District, in the state of Tamil Nadu. ... Tamil Nadu (&#2980;&#2990;&#3007;&#2996;&#3021; &#2984;&#3006;&#2975;&#3009;, Land of the Tamils) is a state at the southern tip of India. ... Suzlon Energy is the worlds largest fully-integrated wind power company. ...

In December 2003, General Electric installed the world's largest offshore wind turbines in Ireland, and plans are being made for more such installations on the west coast, including the possible use of floating turbines. â€œGEâ€ redirects here. ...

On August 15, 2005, China announced it would build a 1000-megawatt wind farm in Hebei for completion in 2020. China reportedly has set a generating target of 20,000 MW by 2020 from renewable energy sources — it says indigenous wind power could generate up to 253,000 MW. Following the World Wind Energy Conference in November 2004, organised by the Chinese and the World Wind Energy Association, a Chinese renewable energy law was adopted. In late 2005, the Chinese government increased the official wind energy target for the year 2020 from 20 GW to 30 GW.[19] is the 227th day of the year (228th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Mexico recently opened La Venta II wind power project as an important step in reducing Mexico's consumption of fossil fuels. The project (88MW) the first of its kind in Mexico, will provide 13 percent of the electricity needs of the state of Oaxaca and by 2012 will have a capacity of 3500 MW.

Another growing market is Brazil, with a wind potential of 143 GW.[20] The federal government has created an incentive program, called Proinfa,[21] to build production capacity of 3300 MW of renewable energy for 2008, of which 1422 MW through wind energy. The program seeks to produce 10% of Brazilian electricity through renewable sources. Brazil produced 320 TWh in 2004. France recently announced a very ambitious target of 12 500 MW installed by 2010. The terawatt hour (TW·h) is a unit for measuring energy. ...

View of wind farm near Muppandal, Tamilnadu in India

### Wind power in Europe

Wind Power in Europe 2006 (MW)
1 Germany 2 233 20 622
2 Spain 1 587 11 615
3 France 810 1 567
4 Portugal 694 1 716
5 UK 634 1 963
6 Italy 417 2 123
7 Netherlands 356 1 560
8 Ireland 250 745
9 Greece 173 746
10 Austria 146 965
11 Poland 69 152
12 Sweden 62 572
13 Lithuania 49 55
14 Hungary 43 61
15 Belgium 26 193
16 Czech Republic 22 50
17 Bulgaria 22 32
18 Denmark & F.I. 11 3 140
19 Finland 4 86
20 Romania 1 3
21 Luxembourg 0 35
22 Estonia 0 32
23 Latvia 0 27
24 Slovenia 0 5
25 Slovakia 0 0
26 Cyprus 0 0
27 Malta 0 0
EU27 (MW) 7 609 48 061
28 Norway 47 314
Europe (MW) 7 708 48 545
ref in discussion

At the end of 2006 renewable energy in Germany provided 11. ... Offshore wind turbines near Copenhagen Some 20 per cent of Danish domestic electricity comes from wind [1]and Denmark is a leading wind power nation in the world. ...

### Small scale

This rooftop-mounted urban wind turbine charges a 12 volt battery and runs various 12 volt appliances within the building on which it is installed.

Small Wind is defined as wind generation systems with capacities of 100 kW or less and are usually used to power homes, farms, and small businesses. Individuals purchase these systems to reduce or eliminate their electricity bills, to avoid the unpredictability of natural gas prices, or simply to generate their own clean power. Download high resolution version (1203x1167, 59 KB)Urbine (rooftop mounted urban wind turbine) The Lakota wind turbine from True North Power has been working well in the 330 Dundas Street location, Toronto, Ontario. ... Download high resolution version (1203x1167, 59 KB)Urbine (rooftop mounted urban wind turbine) The Lakota wind turbine from True North Power has been working well in the 330 Dundas Street location, Toronto, Ontario. ... Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ...

Wind turbines have been used for household electricity generation in conjunction with battery storage over many decades in remote areas, but increasingly, U.S. consumers are choosing to purchase grid-connected turbines in the 1 to 10 kilowatt range to power their whole homes. Household generator units of more than 1 kW are now functioning in several countries, and in every state in the U.S. Symbols representing a single Cell (top) and Battery (bottom), used in circuit diagrams. ...

To compensate for the varying power output, grid-connected wind turbines may utilise some sort of grid energy storage. Off-grid systems either adapt to intermittent power or use photovoltaic or diesel systems to supplement the wind turbine. Ffestiniog pumped storage power station upper reservoir Grid energy storage lets energy producers send excess electricity over the electricity transmission grid to temporary electricity storage sites that become energy producers when electricity demand is greater. ... A solar cell, a form of photovoltaic cell, is a device that uses the photoelectric effect to generate electricity from light, thus generating solar power (energy). ... This article is about the fuel. ...

Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones sometimes, but not always, have direct drive generators, direct current output, aeroelastic blades, lifetime bearings and use a vane to point into the wind; while the larger ones generally have geared power trains, alternating current output, flaps and are actively pointed into the wind. Direct drive generators and aeroelastic blades for large wind turbines are being researched and direct current generators are sometimes used. Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...

In urban locations, where it is difficult to obtain predictable or large amounts of wind energy, smaller systems may still be used to run low power equipment. Distributed power from rooftop mounted wind turbines can also alleviate power distribution problems, as well as provide resilience to power failures. Equipment such as parking meters or wireless internet gateways may be powered by a wind turbine that charges a small battery, replacing the need for a connection to the power grid and/or maintaining service despite possible power grid failures. Distributed generation generates electricity from many small energy sources. ...

While installing a small wind turbine on a roof (rather than a tall tower elsewhere on a property) can be done successfully, there are a few inherent issues that this type of installation faces: Whether the roof can support the turbine's weight, how the building tolerates the vibrations from the spinning rotor, and the turbulence caused by the roof ledge and the resulting unpredictability in wind patterns.

Small-scale wind power in rural Indiana.

The American Wind Energy Association has released several studies on the small wind turbine market in the U.S. and abroad, showing that the U.S. continues to dominate the Small Wind industry.[13] According to another organization, the World Wind Energy Association, it is difficult to assess the total number or capacity of small-scaled wind turbines, but in China alone, there are roughly 300,000 small-scale wind turbines generating electricity.[1]

The dominant model on the market, especially in the United States, is the propeller-shaped "Horizontal Axis" type, which resembles the large, utility-scale turbines used in wind "farms." An alternative model is known as "Vertical Axis," and rotates like a top and can come in many different designs.

There have been a number of recent developments of mini-windmills which could be adapted to home use, including:

• The AeroTecture vertical-axis turbine[26]
• The AeroVironment Architectural Wind Project[27][28]
• The piezoelectric windmill project[29]
• The Swift home wind turbine.[30] The Swift project peaked in 2004 and has had some implementation difficulties while promising to be a low-noise/safe roof-mount/low-cost alternative[31]
• The Motorwave micro-wind turbine[32][33][34]

Consumer guides are available to help potential customers learn about residential-scale wind systems, three of which are: This article is about the machine for converting the kinetic energy in the wind into mechanical energy. ... Piezoelectricity is the ability of certain crystals to produce a voltage when subjected to mechanical stress. ...

• "Small Wind Electric Systems: A U.S. Consumer's Guide" by the Dept. of Energy's Wind Powering America program [14]
• "Wind Turbine Buyer's Guide" From Home Power Magazine[15]
• "Apples & Oranges 2002: Choosing a Home-Sized Wind Generator" [16]

Much more information is also available at the American Wind Energy Association's web site at:

## Wind power: key issues

Wind power can be a controversial issue, and several main areas of dispute are debated between supporters and opponents.

Erection of an Enercon E70-4 in Germany

Download high resolution version (1024x1365, 101 KB) Wikipedia does not have an article with this exact name. ... Download high resolution version (1024x1365, 101 KB) Wikipedia does not have an article with this exact name. ... Enercon E-112 Enercon GmbH, based in Aurich, Northern Germany, is the third-largest wind turbine manufacturer in the world and the market leader in Germany. ...

### Growth and cost trends

Global Wind Energy Council (GWEC) figures show that 2006 recorded an increase of installed capacity of 15,197 megawatts (MW), taking the total installed wind energy capacity to 74,223 MW, up from 59,091 MW in 2005. Despite constraints facing supply chains for wind turbines, the annual market for wind continued to increase at an estimated rate of 32% following the 2005 record year, in which the market grew by 41%. In terms of economic value, the wind energy sector has become one of the important players in the energy markets, with the total value of new generating equipment installed in 2006 reaching €18 billion, or US\$23 billion.[12]

The countries with the highest total installed capacity are Germany (20,621 MW), Spain (11,615 MW), the USA (11,603 MW), India (6,270 MW) and Denmark (3,136). Thirteen countries around the world can now be counted among those with over 1,000 MW of wind capacity. In terms of new installed capacity in 2006, the US leads with 2,454 MW, followed by Germany (2,233 MW), India (1,840 MW), Spain (1,587 MW), China (1,347 MW) and France (810 MW).[12]

In 2004, wind energy cost one-fifth of what it did in the 1980s, and some expected that downward trend to continue as larger multi-megawatt turbines are mass-produced.[35] However, installation costs have increased significantly in 2005 and 2006, and according to the major U.S. wind industry trade group, now average over US\$1,600 per kilowatt,[36] compared to \$1200/kW just a few years before. A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour (2005).[37] Cost per unit of energy produced was estimated in 2006 to be comparable to the cost of new generating capacity in the United States for coal and natural gas: wind cost was estimated at \$55.80 per MWh, coal at \$53.10/MWh and natural gas at \$52.50.[38] Other sources in various studies have estimated wind to be more expensive than other sources (see Economics of new nuclear power plants, Clean coal, and Carbon capture and storage). This article is about the machine for converting the kinetic energy in the wind into mechanical energy. ... The Economics of new nuclear power plants is a controversial subject, since multi-billion dollar investments ride on the choice of an energy source. ... Clean coal is the name attributed to coal chemically washed of minerals and impurities, sometimes gasified, burned and the resulting flue gases treated with steam and reburned so as to make the carbon dioxide in the flue gas economically recoverable. ... Carbon capture and storage (CCS) is an approach to mitigating global warming by capturing carbon dioxide (CO2) from large point sources such as power plants and subsequently storing it instead of releasing it into the atmosphere. ...

Most major forms of electricity generation are capital intensive, meaning that they require substantial investments at project inception, and low ongoing costs (generally for fuel and maintenance). This is particularly true for wind and hydro power, which have fuel costs close to zero and relatively low maintenance costs; in economic terms, wind power has an extremely low marginal cost and a high proportion of up-front capital costs. The estimated "cost" of wind energy per unit of production is generally based on average cost per unit, which incorporates the cost of construction, borrowed funds, return to investors (including cost of risk), estimated annual production, and other components. Since these costs are averaged over the projected useful life of the equipment, which may be in excess of twenty years, cost estimates per unit of generation are highly dependent on these assumptions. Figures for cost of wind energy per unit of production cited in various studies can therefore differ substantially. The cost of wind power also depends on several other factors, such as installation of power lines from the wind farm to the national grid and the frequency of wind at the site in question. In economics and finance, marginal cost is the change in total cost that arises when the quantity produced changes by one unit. ... Marginal cost is a term in economics. ... The National Grid is the high-voltage electric power transmission network in Great Britain, connecting power stations and major substations and ensuring that electricity generated anywhere in Great Britain can be used to satisfy demand elsewhere. ...

Estimates for cost of production use similar methodologies for other sources of electricity generation. Existing generation capacity represents sunk costs, and the decision to continue production will depend on marginal costs going forward, not estimated average costs at project inception. For example, the estimated cost of new wind power capacity may be lower than that for "new coal" (estimated average costs for new generation capacity) but higher than for "old coal" (marginal cost of production for existing capacity). Therefore, the choice to increase wind capacity by building new facilities will depend on more complex factors than cost estimates, including the profile of existing generation capacity. In economics and in business decision-making, sunk costs are costs that have already been incurred and which cannot be recovered to any significant degree. ...

Research from a wide variety of sources in various countries shows that support for wind power is consistently between 70 and 80 per cent amongst the general public.[39]

### Scalability

A key issue debated about wind power is its ability to scale to meet a substantial portion of the world's energy demand. There are significant economic, technical, and ecological issues about the large-scale use of wind power that may limit its ability to replace other forms of energy production. Most forms of electricity production also involve such trade-offs, and many are also not capable of replacing all other types of production for various reasons. A key issue in the application of wind energy to replace substantial amounts of other electrical production is intermittency; see the section below on Economics and Feasibility. At present, it is unclear whether wind energy will eventually be sufficient to replace other forms of electricity production, but this does not mean wind energy cannot be a significant source of clean electrical production on a scale comparable to or greater than other technologies, such as hydropower. Most electrical grids use a mix of different generation types (baseload generating capacity and peaking capacity) to match demand cycles by attempting to match the variable nature of demand to the most economic form of production; with the exception of hydropower, most types of production capacity are not used for all production (hydropower usage is limited by the presence of appropriate geographical sites). For example, nuclear power is effective as a baseload technology, but cannot be easily varied in short timeframes, and gas turbine plants are most economically used as peaking capacity; coal generation is primarily considered appropriate for baseload generation with some capacity to cycle to meet demand. Intermittent power sources are sources of power generation, primarily electricity, whose power output is either variable or intermittent. ... Undershot water wheels on the Orontes River in Hama, Syria Saint Anthony Falls Hydropower is the capture of the energy of moving water for some useful purpose. ...

A significant part of the debate about the potential for wind energy to substitute for other electric production sources is the level of penetration. With the exception of Denmark, no countries or electrical systems produce more than 10% from wind energy, and most are below 2% (of course, this is in large part because wind power is a relatively new technology, with the vast majority of installations having taken place within the last 10 years). While the feasibility of integrating much higher levels (beyond 25%) is debated, significantly more wind energy could be produced worldwide before these issues become significant. In Denmark, wind power now accounts for close to 20% of electricity production[40] and a recent poll of Danes show that 90% want more wind power installed.[41]

### Theoretical potential

Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date[42] found the potential of wind power on land and near-shore to be 72 TW (~171,000 Mtoe), or over fifteen times the world's current energy use and 40 times the current electricity use. The potential takes into account only locations with Class 3 (mean annual wind speeds ≥ 6.9 m/s at 80 m) or better wind regimes, which includes the locations suitable for low-cost (0.03–0.04 \$/kWh) wind power generation and is in that sense conservative. It assumes 6 turbines per square km for 77 m diameter, 1.5 MW-turbines on roughly 13% of the total global land area (though that land would also be available for other compatible uses such as farming). However, the authors are quick to point out that many practical barriers would need to be overcome to reach this theoretical capacity. The calculations of potential assumes a capacity factor of 48% and does not take into account the practicality of reaching the windy sites, of transmission (including 'choke' points), of competing land uses, of transporting power over large distances, or of switching to wind power. For other uses, see Watt (disambiguation). ... The ton of oil equivalent (TOE) is a unit for measuring energy. ...

To determine the more realistic technical potential, it is essential to estimate how large a fraction of this land could be made available to wind power. In the 2001 IPCC report, it is assumed that a use of 4% – 10% of that land area would be practical.

Although the theoretical potential is vast, the amount of production that could be economically viable depends on a number of exogenous and endogenous factors, including the cost of other sources of electricity and the future cost of wind energy farms.[weasel words]

Offshore resources experience mean wind speeds about 90% greater than those on land, so offshore resources could contribute about seven times more energy than land.[43][44] This number could also increase with higher altitude or airborne wind turbines.[45]

### Economics and feasibility

Some of the over 6,000 wind turbines at Altamont Pass, in California. Developed during a period of tax incentives in the 1980s, this wind farm has more turbines than any other in the United States, producing about 125 MW.[46] Considered largely obsolete, these turbines produce only a few tens of kilowatts each.

Wind energy in many jurisdictions receives some financial or other support to encourage its development. A key issue is the comparison to other forms of energy production, and their total cost. Two main points of discussion arise: direct subsidies and externalities for various sources of electricity, including wind. Wind energy benefits from subsidies of various kinds in many jurisdictions, either to increase its attractiveness, or to compensate for subsidies received by other forms of production or which have significant negative externalities. Without the handsome tax incentives (also know as subsidies) in fact, almost no wind power installation is economically feasible at present.[citation needed] Image File history File linksMetadata Wind_energy_converter5. ... Image File history File linksMetadata Wind_energy_converter5. ... The Altamont Pass is a mountain pass in Northern California, United States, located between Livermore in the Livermore Valley and Tracy in the San Joaquin Valley. ... In economics, a subsidy is generally a monetary grant given by a government to lower the price faced by producers or consumers of a good, generally because it is considered to be in the public interest. ... An externality occurs in economics when a decision (for example, to pollute the atmosphere) causes costs or benefits to individuals or groups other than the person making the decision. ...

Most forms of energy production create some form of negative externality: costs that are not paid by the producer or consumer of the good. For electric production, the most significant externality is pollution, which imposes costs on society in the form of increased health expenses, reduced agricultural productivity, and other problems. In addition, carbon dioxide, a greenhouse gas produced when fossil fuels are burned for electricity production, may impose even greater costs on society in the form of global warming. Few mechanisms currently exist to impose (or internalise) these external costs in a consistent way between various industries or technologies, and the total cost is highly uncertain. Other significant externalities can include national security expenditures to ensure access to fossil fuels, remediation of polluted sites, destruction of wild habitat, loss of scenery/tourism, etc. An externality occurs in economics when a decision (for example, to pollute the atmosphere) causes costs or benefits to individuals or groups other than the person making the decision. ... Air pollution Pollution is the introduction of pollutants (whether chemical substances, or energy such as noise, heat, or light) into the environment to such a point that its effects become harmful to human health, other living organisms, or the environment. ... Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Top: Increasing atmospheric CO2 levels as measured in the atmosphere and ice cores. ... Global warming refers to the increase in the average temperature of the Earths near-surface air and oceans in recent decades and its projected continuation. ...

Wind energy supporters argue that, once external costs and subsidies to other forms of electrical production are accounted for, wind energy is amongst the most cost-effective forms of electrical production. Critics argue that the level of required subsidies, the small amount of energy needs met, and the uncertain financial returns to wind projects — that is, the all-in cost of wind energy compared to other technologies - make it inferior to other energy sources. Intermittency and other characteristics of wind energy also have costs that may rise with higher levels of penetration, and may change the cost-benefit ratio.

• Conventional and nuclear power plants receive substantial direct and indirect governmental subsidies.[citation needed] If a comparison is made on total production costs (including subsidies), wind energy may or may not be competitive compared to other energy sources.[citation needed] If the full costs (environmental, health, etc.) are taken into account, wind energy may be competitive in more cases. Wind energy costs have generally decreased due to technology development and scale enlargement. However, the cost of other capital intensive generation technologies, such as nuclear and fossil fueled plants, is also subject to cost reductions due to economies of scale and technological improvements.
• To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit for each kilowatt-hour produced; at 1.9 cents per kilowatt-hour in 2006, the credit has a yearly inflationary adjustment. Another tax benefit is accelerated depreciation. Many American states also provide incentives, such as exemption from property tax, mandated purchases, and additional markets for "green credits." Countries such as Canada and Germany also provide incentives for wind turbine construction, such as tax credits or minimum purchase prices for wind generation, with assured grid access (sometimes referred to as feed-in tariffs). These feed-in tariffs are typically set well above average electricity prices.
• Many potential sites for wind farms are far from demand centers, requiring substantially more money to construct new transmission lines and substations.
• Intermittency and the non-dispatchable nature of wind energy production can raise costs for regulation, incremental operating reserve, and (at high penetration levels) could require demand-side management or storage solutions. However, it is highly unlikely that any of these storage systems could replace the energy deficit produced, say, on windless days. See 'Grid Energy Storage' section below.
• Since the primary cost of producing wind energy is construction and there are no fuel costs, the average cost of wind energy per unit of production is dependent on a few key assumptions, such as the cost of capital and years of assumed service. The marginal cost of wind energy once a plant is constructed is close to zero.[citation needed]
• The cost of wind energy production has fallen rapidly since the early 1980s, primarily due to technological improvements, although the cost of construction materials (particularly metals) and the increased demand for turbine components caused price increases in 2005-06. Many expect further reductions in the cost of wind energy through improved technology, better forecasting, and increased scale. Since the cost of capital plays a large part in projected cost, risk (as perceived by investors) will affect projected costs per unit of electricity.
• Apart from regulatory issues and externalities, decisions to invest in wind energy will also depend on the cost of alternative sources of energy. Natural gas, oil and coal prices, the main production technologies with significant fuel costs, will therefore also be a determinant in the choice of the level of wind energy.
• The commercial viability of wind power also depends on the pricing regime for power producers. Electricity prices are highly regulated worldwide, and in many locations may not reflect the full cost of production, let alone indirect subsidies or negative externalities. Certain jurisdictions or customers may enter into long-term pricing contracts for wind to reduce the risk of future pricing changes, thereby ensuring more stable returns for projects at the development stage. These may take the form of standard offer contracts, whereby the system operator undertakes to purchase power from wind at a fixed price for a certain period (perhaps up to a limit); these prices may be different than purchase prices from other sources, and even incorporate an implicit subsidy.
• In jurisdictions where the price paid to producers for electricity is based on market mechanisms, revenue for all producers per unit is higher when their production coincides with periods of higher prices. The profitability of wind farms will therefore be higher if their production schedule coincides with these periods (generally, high demand / low supply situations). If wind represents a significant portion of supply, average revenue per unit of production may be lower as more expensive and less-efficient forms of generation, which typically set revenue levels, are displaced from economic dispatch. [citation needed] This may be of particular concern if the output of many wind plants in a market have strong temporal correlation. In economic terms, the marginal revenue of the wind sector as penetration increases may diminish.

This article is about applications of nuclear fission reactors as power sources. ... Full cost accounting (FCA) generally refers to the process of collecting and presenting information (costs as well as advantages) for each proposed alternative when a decision is necessary. ... ... The kilowatt-hour (symbol: kW·h) is a unit for measuring energy. ... Accelerated depreciation refers to allowing a company to depreciate an asset (such as a unit of machinery) at a higher-than-normal rate, thus reducing taxes payable. ... Intermittent power sources are sources of power generation, primarily electricity, whose power output is either variable or intermittent. ... In economics and finance, marginal cost is the change in total cost that arises when the quantity produced changes by one unit. ... The cost of capital for a firm is a weighted sum of the cost of equity and the cost of debt (see the financing decision). ... This article contains information that has not been verified and thus might not be reliable. ... In microeconomics, Marginal Revenue (MR) is the extra revenue that an additional unit of product will bring a firm. ...

## Intermittency and variability

Electricity generated from wind power can be highly variable at several different timescales: from hour to hour, daily, and seasonally. Annual variation also exists, but is not as significant. This variability can present substantial challenges to incorporating large amounts of wind power into a grid system, since to maintain grid stability, energy supply and demand must remain in balance. Intermittent power sources are sources of power generation, primarily electricity, whose power output is either variable or intermittent. ...

While the negative effects of intermittency have to be considered in the economics of power generation, wind is unlikely to suffer momentary failure of large amounts of generation, which may be a concern with some traditional power plants. In this sense, it may be more reliable (albeit variable) due to the distributed nature of generation. That said, winds often stagnate during periods of peak demand, such as during heat waves. [20][21]

Wind speeds are generally much lower during periods of the highest peak-load demand (the months of June, July and August) in North America.[citation needed] There is an inverse relationship with wind speed and peak demand of electricity.[citation needed] Many grid planners do not even adjust their calculations to account for wind power installations because of that inverse (albeit happenstance) relationship.[citation needed]

Intermittency is a major problem that may well limit the effectiveness of wind power generation. The 'Renewable Energy in Scotland Inquiry' strongly noted the intermittent nature of wind power, concluding:

Wind turbines by the nature of the prime mover only offer sporadic energy production. Wind energy will always be a secondary, intermittent, unreliable energy source and can never satisfy a base load demand. This is the direct opposite of most other forms of electricity generation. (Wind power) is a profligate waste of our most precious resource - wild land.[47]

However, a study commissioned by the US state of Minnesota[48] considered penetration of up to 25%, and concluded that integration issues would be manageable and have incremental costs of less than one-half cent (\$0.0045) per kWh.

### Grid management

Grid operators routinely control the supply of electricity by cycling generating plants on or off at different timescales. Most grids also have some degree of control over demand, through either demand management or load shedding. Management of either supply or demand has economic implications for suppliers, consumers and grid operators but is already widespread. Demand Management is the art or science of controlling economic demand to avoid a recession. ... Rolling blackout refers to an intentionally-engineered electrical power outage, caused by insufficient available resources to meet prevailing demand for electricity. ...

Variability of wind output creates a challenge to integrating high levels of wind into energy grids based on existing operating procedures. Critics of wind energy argue that methods to manage variability increase the total cost of wind energy production substantially at high levels of penetration, while supporters note that tools to manage variable energy sources already exist and are economical, given the other advantages of wind energy. Supporters note that the variability of the grid due to the failure of power stations themselves, or the sudden change of loads, exceeds the likely rate of change of even very large wind power penetrations.

There is no generally accepted "maximum" level of wind penetration, and practical limitations will depend on the configuration of existing generating plants, pricing mechanisms, capacity for storage or demand management, and other factors.

A number of studies for various locations have indicated that at least 20% of the total electrical energy consumption may be incorporated with minimal difficulty[49]. These studies have generally been for locations with reasonable geographic diversity of wind; suitable generation profile (such as some degree of dispatchable energy and particularly hydropower with storage capacity); existing or contemplated demand management; and interconnection/links into a larger grid area allowing for import and export of electricity when needed. Beyond this level, there are few technical reasons why more wind power could not be incorporated, but the economic implications become more significant and other solutions may be preferred.

At present, very few locations have penetration of wind energy above 5%. Germany, Spain, and Portugal all have penetration levels above 20%, however, and Denmark's penetration is over 40%, demonstrating that the technical issues are manageable at relatively high levels. The penetration of intermittent powersources in Denmark is even higher since 20% of Denmarks electricity is produced by decentral combined heat-powerplants that only produce electricity when there is a demand for heat. However, it should also be noted that the Danish grid is heavily interconnected to the German and broader European electrical grid and can both supply and demand electricity from a broader area than just the Danish grid. In practice Denmark has solved its grid management problems by exporting almost half of its windpower to Norway. The correlation between electricity export and wind power production is very strong.[50].

### Grid energy storage

See article: Grid energy storage. Ffestiniog pumped storage power station upper reservoir Grid energy storage lets energy producers send excess electricity over the electricity transmission grid to temporary electricity storage sites that become energy producers when electricity demand is greater. ...

A grid energy storage system is a potential means of increasing the amount of usable wind energy in a given electrical system (penetration rates) by making use of 'wind energy storage systems'. Effectively, "surplus" wind energy could be used to store electricity in usable form. Storage of electricity would effectively arbitrage between the cost of electricity at periods of high supply and low demand, and the higher cost at periods of high demand and low supply. The potential revenue from this arbitrage must be balanced against the installation cost of storage facilities and efficiency losses. Many potential technologies exist to store usable electric energy, including pumped storage hydroelectricity, air ballast, battery technologies, and even flywheel energy storage. In economics and finance, arbitrage is the practice of taking advantage of a price differential between two or more markets: a combination of matching deals are struck that capitalize upon the imbalance, the profit being the difference between the market prices. ... Diagram of the TVA pumped storage facility at Racoon Mountain Pumped storage hydroelectricity is a method of storing and producing electricity to supply high peak demands. ... NASA G2 flywheel Flywheel Energy Storage (FES) works by accelerating a rotor (flywheel) to a very high speed and maintaining the energy in the system as rotational energy. ...

• Pumped storage: Pumped storage hydroelectric systems have been implemented on a large scale for national grids, can be brought online within tens of seconds, and have approximately 80% efficiency in storage and retrieval of electrical energy.[51] Most existing pumped storage is designed for meeting fluctuations in demand rather than long-term storage, however, and consequently tends to have relatively modest storage capacity. As an example, the Tianhuangping Pumped-Storage Hydro Plant in China[52] has a reservoir capacity of eight million cubic meters with a vertical distance of 600m. At 0.277kWh per cubic meter per hundred vertical meters[53], that represents 13 million kWh of stored gravitational potential energy (convertible to electricity at about 80% efficiency), or only about 2% of China's daily electricity consumption[54]. At a construction cost of \$1.1B, however, the plant demonstrates that pumped storage costs roughly \$100/kWh of storage for current designs. Main article: Pumped-storage hydroelectricity
• Flow batteries: This system of electrical storage, currently being piloted on wind farms, uses rechargeable flow batteries as a rapid-response storage medium [55]. Vanadium redox flow batteries are currently installed at Huxley Hill wind farm (Australia), Tomari Wind Hills at Hokkaidō (Japan), as well as in other non-wind farm applications. A further 12 MWh flow battery is to be installed at the Sorne Hill wind farm (Ireland) [56]. These storage systems are designed to smooth out transient fluctuations in wind energy supply. The redox flow battery mentioned in the first article cited above has a capacity of 6 MWh, which represents under an hour of electrical flow from this particular wind farm (at 25% capacity factor on its 30 MW rated capacity).
• Flywheel storage: This potential solution has been implemented by EDA [57] in the Azores on the islands of Graciosa and Flores. This system uses a 18MWs flywheel to improve power quality and thus allow increased renewable energy usage. As the description suggests, these systems are again designed to smooth out transient fluctuations in supply, and could never be used to cope with an outage of couple of days or more. The largest flywheel energy storage systems available can hold up to 133 kwh of energy.
• Hydrogen storage: Hydrogen is also being developed as an electrical power storage medium. Hydrogen is created using electrolysis of water and then stored for later use with hydrogen based generating equipment. In July 2007 the government of Newfoundland and Labrador announced[58] a five year pilot programme for a wind-hydrogen power system on the island of Ramea, which will replace the existing wind-diesel generating system. However, substantial energy losses are involved in the hydrogen storage cycle of production, liquification or compression, and conversion back to electricity. One report for Physorg science magazine[59] indicates that the losses encountered with the hydrogen compression cycle are around 78%, while the hydrogen liquification cycle's losses are in the order of 81%.[60]
• Lithium batteries: In 2006, several companies (Altairnano, A123 Systems, Electrovaya) announced lithium batties which could power future EVs (Electric Vehicles) and PHEVs (Plug-in Hybrid Electric Vehicles). A feature of these batteries is a high number of charge/discharge cycles per battery lifetime (Altairnano claim 15,000 cycles). By plugging thousands of cars to the grid when they are not in use (95% of the day on average), the electric car becomes an asset to the grid, rather than a drain only. Each participating vehicle would require electrical upload as well as download capability.
• Storage as pressurized gas, including compressed air. Cavern air storage is another method of storing off-peak electricity or wind energy, through the storage of compressed air in a large underground cavern. The system is actually a hybrid power generation system, as the stored compressed air is mixed with natural gas before being combusted in a conventional gas turbine engine (probably a modified aero engine). Two plants exist with this design at Huntorf in Germany and Mckintosh in Alabama, which both use off-peak energy for the air compression.[61] A new plant, this time combined with a 75 - 150 MW wind farm for the air compression, is under consideration in Iowa.[62] Power output of the Mckintosh and Iowa gas/compressed air generation systems is given as 2-300 MW. The duration of the Mckintosh plant is 24 hours, with the extended operation being achieved through the combined burning of a natural gas/compressed air mix.

## Predictability

Related to, but essentially different from variability, is the short-term (hourly or daily) predictability of wind plant output. Like other electricity sources, wind energy must be "scheduled" - this presents a challenge because the nature of this energy source makes it inherently variable over time. To overcome this problem, wind power forecasting methods are employed by utilities or system operators. Despite the use of forecasting, the predictability of wind plant output remains low for a variety of reasons. A wind power forecast corresponds to an estimate of the expected production of one or more wind turbines (referred to as a wind farm) in the near future. ...

## Ecology and pollution

#### CO2 emissions and pollution

It is sometimes said that wind energy, for example, does not reduce carbon dioxide emissions because the intermittent nature of its output means it needs to be backed up by fossil fuel plants. Wind turbines do not displace fossil generating capacity on a one-for-one basis. But it is unambiguously the case that wind energy can displace fossil fuel-based generation, reducing both fuel use and carbon dioxide emissions.[63]

Wind power consumes no fuel for continuing operation, and has no emissions directly related to electricity production. Wind power stations, however, consume resources in manufacturing and construction, as do most other power production facilities. Wind power may also have an indirect effect on pollution at other production facilities, due to the need for reserve and regulation, and may affect the efficiency profile of plants used to balance demand and supply, particularly if those facilities use fossil fuel sources. Compared to other power sources, however, wind energy's direct emissions are low, and the materials used in construction (concrete, steel, fiberglass, generation components) and transportation are straightforward. Wind power's ability to reduce pollution and greenhouse gas emissions will depend on the amount of wind energy produced, and hence scalability, as well as the profile of other generating capacity.

• A study by the Irish national grid stated clearly that "Producing electricity from wind reduces the consumption of fossil fuels and therefore leads to emissions savings", and found reductions in CO2 emissions ranging from 0.59 tonnes of CO2 per MWh to 0.33 tonnes per MWh.[64]
• Wind power is a renewable resource, which means using it will not deplete the earth's supply of fossil fuels. It also is a clean energy source, and operation does not produce carbon dioxide, sulfur dioxide, mercury, particulates, or any other type of air pollution, as do conventional fossil fuel power sources.
• Electric power production is only part (about 39% in the USA[65]) of a country's energy use, so wind power's ability to mitigate the negative effects of energy use — as with any other clean source of electricity — is limited (except with a potential transition to electric or hydrogen vehicles). Wind power contributed less than 1% of the UK's national electricity supply[37] in 2004 and hence had negligible effects on CO2 emissions, which continued to rise in 2002 and 2003 (Department of Trade and Industry); the growth of installed wind capacity in the UK has been impressive (installed wind capacity doubled from 2002 to 2004, and again from end-2004 to mid-2006), but from low levels. Until wind energy achieves substantially greater scale worldwide, its ability to contribute will be limited.
• Groups such as the UN's Intergovernmental Panel on Climate Change cite wind power as a key mitigation technology available today to reduce carbon emissions in the energy supply .[66] Intergovernmental Panel on Climate Change's 2007 Assessment Report
• During manufacture of the wind turbine, steel, concrete, aluminum and other materials will have to be made and transported using energy-intensive processes, generally using fossil energy sources.
• The energy return on investment (EROI) for wind energy is equal to the cumulative electricity generated divided by the cumulative primary energy required to build and maintain a turbine. The EROI for wind ranges from 5 to 35, with an average of around 18. This places wind energy in a favorable position relative to conventional power generation technologies in terms of EROI. Baseload coal-fired power generation has an EROI between 5 and 10:1. Nuclear power is probably no greater than 5:1, although there is considerable debate regarding how to calculate its EROI. The EROI for hydropower probably exceeds 10, but in most places in the world the most favorable sites have been developed.[67]
• Net energy gain for wind turbines has been estimated in one report to be between 17 and 39 (i.e. over its life-time a wind turbine produces 17-39 times as much energy as is needed for its manufacture, construction, operation and decommissioning). A similar Danish study determined the payback ratio to be 80, which means that a wind turbine system pays back the energy invested within approximately 3 months.[68] This is to be compared with payback ratios of 11 for coal power plants and 16 for nuclear power plants, though such figures do not take into account the energy content of the fuel itself, which would lead to a negative energy gain.[69]
• The ecological and environmental costs of wind plants are paid by those using the power produced, with no long-term effects on climate or local environment left for future generations.

#### Ecology

• Because it uses energy already present in the atmosphere, and can displace fossil-fuel generated electricity (with its accompanying carbon dioxide emissions), wind power mitigates global warming. While wind turbines might kill some bird and bat species, conventionally fueled power plants also have the potential to affect other species through climate changes, acid rain, and pollution.
• Unlike fossil fuel and nuclear power stations, which circulate or evaporate large amounts of water for cooling, wind turbines do not need water to generate electricity.

Global carbon dioxide emissions 1800â€“2000 Global average surface temperature 1850 to 2006 Mitigation of global warming involves taking actions aimed at reducing the extent of global warming. ...

#### Ecological footprint

Large-scale onshore and near-shore wind energy facilities (wind farms) can be controversial due to aesthetic reasons and impact on the local environment. Large-scale offshore wind farms are not visible from land and according to a comprehensive 8-year Danish Offshore Wind study on "Key Environmental Issues" have no discernible effect on aquatic species and no effect on migratory bird patterns or mortality rates. Modern wind farms make use of large towers with impressive blade spans, occupy large areas and may be considered unsightly at onshore and near-shore locations. They usually do not, however, interfere significantly with other uses, such as farming. The impact of onshore and near-shore wind farms on wildlife—particularly migratory birds and bats—is hotly debated, and studies with contradictory conclusions have been published. Two preliminary conclusions for onshore and near-shore wind developments seem to be supported: first, the impact on wildlife is likely low compared to other forms of human and industrial activity; second, negative impacts on certain populations of sensitive species are possible, and efforts to mitigate these effects should be considered in the planning phase. According to recent estimates published in Nature, each wind turbine kills on average 0.03 birds per year, or one kill per thirty turbines [70]. However, the birds that are killed may on average be larger, so their populations affected more strongly by individual deaths. Aesthetic issues are important for onshore and near-shore locations in that the "visible footprint" may be extremely large compared to other sources of industrial power (which may be sited in industrially developed areas), and wind farms may be close to scenic or otherwise undeveloped areas. Offshore wind development locations remove the visual aesthetic issue by being at least 10 km from shore and in many cases much further away. Wind turbines in Neuenkirchen, Dithmarschen (Germany). ... This article is about the physical universe. ...

A wind turbine at Greenpark, Reading, England

Image File history File linksMetadata Size of this preview: 448 Ã— 599 pixelsFull resolution (1712 Ã— 2288 pixel, file size: 547 KB, MIME type: image/jpeg) Alt title of Image:Greenpark. ... Image File history File linksMetadata Size of this preview: 448 Ã— 599 pixelsFull resolution (1712 Ã— 2288 pixel, file size: 547 KB, MIME type: image/jpeg) Alt title of Image:Greenpark. ... -1... , Reading is a town, unitary authority (the Borough of Reading) and urban area in the English county of Berkshire. ... For other uses, see England (disambiguation). ...

#### Land use

• Clearing of wooded areas is often unnecessary, as the practice of farmers leasing their land out to companies building wind farms is common. In the U.S., farmers may receive annual lease payments of two thousand to five thousand dollars per turbine.[71] The land can still be used for farming and cattle grazing. Less than 1% of the land would be used for foundations and access roads, the other 99% could still be used for farming.[72] Turbines can be sited on unused land in techniques such as center pivot irrigation.
• The clearing of trees around onshore and near-shore tower bases may be necessary to enable installation. This is an issue for potential sites on mountain ridges, such as in the northeastern U.S.[73]
• Wind turbines should ideally be placed about ten times their diameter apart in the direction of prevailing winds and five times their diameter apart in the perpendicular direction for minimal losses due to wind park effects. As a result, wind turbines require roughly 0.1 square kilometres of unobstructed land per megawatt of nameplate capacity. A 2 GW wind farm, which might produce as much energy each year as a 1 GW baseload power plant, might have turbines spread out over an area of approximately 200 square kilometres.
• Areas under onshore and near-shore windfarms can be used for farming, and are protected from further development.
• Although there have been installations of wind turbines in urban areas (such as Toronto's exhibition place), these are generally not used. Buildings may interfere with wind, and the value of land is likely too high if it would interfere with other uses to make urban installations viable. Installations near major cities on unused land, particularly offshore for cities near large bodies of water, may be of more interest. Despite these issues, Toronto's demonstration project demonstrates that there are no major issues that would prevent such installations where practical, although non-urban locations are expected to predominate.
• Offshore locations, such as that being developed on a large underwater plateau in eastern Lake Ontario by Trillium Power use no land per se and avoid known shipping channels. Some offshore locations are uniquely located close to ample transmission and high load centres however that is not the norm for most offshore locations. Most offshore locations are at considerable distances from load centres and may face transmission and line loss challenges.
• Wind turbines located in agricultural areas may create concerns by operators of cropdusting aircraft. Operating rules may prohibit approach of aircraft within a stated distance of the turbine towers; turbine operators may agree to curtail operations of turbines during cropdusting operations.

Pivot irrigation in progress. ... A base load power plant is one that provides a steady flow of power regardless of total power demand by the grid. ... Aerial application, referred to by many as crop dusting, involves spraying crops with fertilizers, pesticides, and fungicides from an agricultural aircraft. ...

#### Impact on wildlife

• Onshore and near-shore studies show that the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities such as traffic, hunting, power lines and high-rise buildings and especially the environmental impacts of using non-clean power sources. For example, in the UK, where there are several hundred turbines, about one bird is killed per turbine per year; 10 million per year are killed by cars alone.[74] In the United States, onshore and near-shore turbines kill 70,000 birds per year, compared to 57 million killed by cars and 97.5 million killed by collisions with plate glass.[75] Another study suggests that migrating birds adapt to obstacles; those birds which don't modify their route and continue to fly through a wind farm are capable of avoiding the large offshore windmills,[76] at least in the low-wind non-twilight conditions studied. In the UK, the Royal Society for the Protection of Birds (RSPB) concluded that "The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds."[77] It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy.
• Some onshore and near-shore windmills kill birds, especially birds of prey.[78] More recent siting generally takes into account known bird flight patterns, but some paths of bird migration, particularly for birds that fly by night, are unknown although a 2006 Danish Offshore Wind study showed that radio tagged migrating birds traveled around offshore wind farms. A Danish survey in 2005 (Biology Letters 2005:336) showed that less than 1% of migrating birds passing an offshore wind farm in Rønde, Denmark, got close to collision, though the site was studied only during low-wind non-twilight conditions. A survey at Altamont Pass, California, conducted by a California Energy Commission in 2004 showed that onshore turbines killed between 1,766 and 4,721[79] birds annually (881 to 1,300 of which were birds of prey). Radar studies of proposed onshore and near-shore sites in the eastern U.S. have shown that migrating songbirds fly well within the reach of large modern turbine blades. In Australia, a proposed onshore/near-shore wind farm was canceled before production because of the possibility that a single endangered bird of prey was nesting in the area[citation needed].
• An onshore/near-shore wind farm in Norway's Smøla islands is reported to have destroyed a colony of sea eagles, according to the British Royal Society for the Protection of Birds.[citation needed] The society said turbine blades killed nine of the birds in a 10 month period, including all three of the chicks that fledged that year. Norway is regarded as the most important place for white-tailed eagles.
• The numbers of bats killed by existing onshore and near-shore facilities has troubled even industry personnel.[80] A study in 2004 estimated that over 2200 bats were killed by 63 onshore turbines in just six weeks at two sites in the eastern U.S.[81] This study suggests some onshore and near-shore sites may be particularly hazardous to local bat populations and more research is urgently needed. Migratory bat species appear to be particularly at risk, especially during key movement periods (spring and more importantly in fall). Lasiurines such as the hoary bat (Lasiurus cinereus), red bat (Lasiurus borealis), and the semi-migratory silver-haired bats (Lasionycteris noctivagans) appear to be most vulnerable at North American sites. Almost nothing is known about current populations of these species and the impact on bat numbers as a result of mortality at windpower locations. Offshore wind sites 10 km or more from shore do not interact with bat populations.

This article needs additional references or sources for verification. ... This article is about the hunting of prey by human society. ... Power line redirects here. ... Taipei 101, the worlds tallest skyscraper by roof height on high rise. ... Fossil fuels are hydrocarbon-containing natural resources such as coal, petroleum and natural gas. ... The Royal Society for the Protection of Birds (RSPB) is Europes largest wildlife conservation charity. ... Wind turbines in Neuenkirchen, Dithmarschen (Germany). ... Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... If you are looking for other meanings of the term, refer to Bird of prey (disambiguation). ... Flock of Barnacle Geese during autumn migration Bird migration refers to the regular seasonal journeys of varying distances undertaken by many species of birds. ... There are very few or no other articles that link to this one. ... An endangered species is a species whose population is so small that it is in danger of becoming extinct. ... Binomial name (Linnaeus, 1758) Light Green: nesting area Blue: wintering area Dark Green: all-year Synonyms Falco albicilla Linnaeus, 1758 Haliaeetus albicilla albicilla Haliaeetus albicilla groenlandicus The White-tailed Eagle (Haliaeetus albicilla[1]), also known as the Sea Eagle, Erne (sometimes Ern), or White-tailed Sea-eagle is a very... â€œChiropteraâ€ redirects here. ... Binomial name Lasiurus cinereus (Beauvois, 1796) The hoary bat (Lasiurus cinereus) is a hairy-tailed bat (genus Lasiurus) in the family of vesper bats (Vespertilionidae). ... The Eastern Red Bat (Lasiurus borealis) is a species of bat from the Vespertilionidae family. ... The Silver-haired bat is a medium-size bat. ...

#### Offshore and Ocean Noise

As the number of offshore wind farms increase and move further into deeper water, the question arises if the ocean noise that is generated due to mechanical motion of the turbines and other vibrations which can be transmitted via the tower structure to the sea, will become significant enough to harm sea mammals. Tests carried out in Denmark for shallow installations showed the levels were only significant up to a few hundred metres. However, sound injected into deeper water will travel much further and will be more likely to impact bigger creatures like whales which tend to use lower frequencies than porpoises and seals. A recent study found that wind farms add 80-110 dB to the existing low-frequency ambient noise (under 400 Hz) and this could impact baleen whales communication and stress levels, and possibly prey distribution. [22]

#### Safety and aesthetics

On the issue of safety, the British Wind Energy Association has said:

"...wind energy is one of the safest energy technologies, and enjoys an outstanding health & safety record. In over 20 years of operating experience and with more than 50,000 machines installed around the world, no member of the public has ever been harmed by operating wind turbines. High standards exist for the design and operation of wind energy projects as well as close industry co-operation with the certification and regulatory bodies in those countries where wind energy is deployed."[82]

There have been a number of fatalities from accidents involving wind turbines. Most involve falls or workers becoming caught in machinery while performing maintenance inside turbine housings while blade failures and falling ice have also accounted for a number of deaths. Notable public fatalities have resulted from distracted motorists seeing wind turbines along highways. [83]

Notable negative aesthetic effects of wind turbines include:

• Recorded experience that onshore and near-shore wind turbines are noisy and visually intrusive creates resistance to the establishment of land-based wind farms in many places. Moving the turbines far offshore (10 km or more) mitigates the problem, but offshore wind farms may be more expensive and transmission to on-shore locations may present challenges in many but not all cases.
• Some residents near onshore and near-shore windmills complain of "shadow flicker", which is the alternating pattern of sun and shade caused by a rotating windmill casting a shadow over residences. Efforts are made when siting onshore and near-shore turbines to avoid this problem.
• Large onshore and near-shore wind towers require aircraft warning lights, which create light pollution at night, which bothers humans and can disrupt the local ecosystem. Complaints about these lights have caused the FAA to consider allowing a less than 1:1 ratio of lights per turbine in certain areas.[23]
Windmills at La Mancha, Spain, made famous by the 1605 novel Don Quixote, are a national treasure.

• Improvements in blade design and gearing have quietened modern turbines to the point where a normal conversation can be held underneath one. In December 2006, a jury in Texas denied a suit for private nuisance against FPL Energy for noise pollution after the company demonstrated that noise readings were not excessive, with the highest reading reaching 44 decibels, which was characterized as approximately the same noise level as a wind of 10 miles per hour.[24] The suit was initially for visual intrusion,[25] but that was disallowed, so it concentrated on noise, which with the large spreads involved, was bound to fail). Texas civil case law requires proof of personal injury in a suit against a neighbor's activities (Klein v. Gehrung, 25 Tex. Supp. 232), so even if the plaintiffs had presented data showing more substantial noise, they would not have prevailed unless they could prove injury.
• Newer wind farms have more widely spaced turbines due to the greater power of the individual wind turbines, and to look less cluttered.
• The aesthetics of onshore and near-shore wind turbines have been compared favorably to those of pylons from conventional power stations.
• Offshore sites have on average a considerably higher energy yield than onshore sites, and generally cannot be seen from the shore even on the clearest of days.

## Hurricanes

Main article: Hurricane

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Image File history File links Portal. ... Image File history File links Sustainable_development. ... Image File history File links Commons-logo. ...

### Green energy

A solar trough array is an example of green energy Green energy is a term describing what is thought to be environmentally friendly sources of power and energy. ... A green tax shift is a fiscal policy which lowers the taxes on income including wages and profit, and raises taxes on consumption, particularly the unsustainable consumption of non-renewable resources. ... Ffestiniog pumped storage power station upper reservoir Grid energy storage lets energy producers send excess electricity over the electricity transmission grid to temporary electricity storage sites that become energy producers when electricity demand is greater. ... Renewable energy effectively utilizes natural resources such as sunlight, wind, tides and geothermal heat, which are naturally replenished. ... For other uses, see Wind (disambiguation). ... A Dutch tower windmill, sporting sails, surrounded by tulips A windmill is an engine powered by the wind to produce energy, often contained in a large building as in traditional post mills, smock mills and tower mills. ... A wind farm is a collection of wind turbines in the same location. ... This article is about the machine for converting the kinetic energy in the wind into mechanical energy. ... Main article: Wind Power A recent development in Wind Power is the introduction of Merchant Wind Power initiatives where an owners of brown field sites, such as heavy industry, locates Wind Turbines on their land that exclusively supply them with green electricity. ...

### By country

This is a List of large wind farms, which are operating or are under construction: Alinta Wind Farm, Western Australia (90 MW) (Australia) Altamont Pass Wind Farm (606 MW) (USA) Big Horn Wind Farm (200 MW) (USA) Brazos Wind Ranch (160 MW) (USA) Centennial Wind Farm (120 MW) (USA) Champion...

## References

1. ^ a b c d World Wind Energy Association Statistics
2. ^ European wind companies grow in U.S.
3. ^ WWEA
4. ^ http://www.ieawind.org/AnnexXXV/Meetings/Oklahoma/IEA%20SysOp%20GWPC2006%20paper_final.pdf IEA Wind Summary Paper, Design and Operation of Power Systems with Large Amounts of Wind Power, September 2006
5. ^ Mapping the global wind power resource
6. ^ Biomass Resources for Energy and Industry
7. ^ Nuclear Energy Institute. Nuclear Facts. Retrieved on 2006-07-23.
8. ^ Mitchell 2006
9. ^ Meteorological Tower Installation
10. ^ David Cohn. Windmills in the Sky. Wired News: Windmills in the Sky. San Francisco: Wired News. Retrieved on July 28, 2006.
11. ^ Magenn Power Inc. corporate website. Retrieved on August 18, 2006.
12. ^ a b c Global Wind Energy Council (GWEC) statistics.
13. ^ European Wind Energy Association (EWEA) statistics.
14. ^ http://awea.org/projects
15. ^ http://www.eia.doe.gov/cneaf/electricity/epm/epm_sum.html
16. ^ Tapping the Wind — India (February 2005). Retrieved on 2006-10-28.
17. ^ Watts, Himangshu (November 11 2003). Clean Energy Brings Windfall to Indian Village. Reuters News Service. Retrieved on 2006-10-28.
18. ^ Suzlon Energy
19. ^ Lema, Adrian and Kristian Ruby, ”Between fragmented authoritarianism and policy coordination: Creating a Chinese market for wind energy”, Energy Policy, Vol. 35, Isue 7, July 2007
20. ^ Atlas do Potencial Eólico Brasileiro. Retrieved on 2006-04-21.
21. ^ Eletrobrás — Centrais Elétricas Brasileiras S. A — Projeto Proinfa. Retrieved on 2006-04-21.
22. ^ Wind Energy: Rapid Growth (PDF). Canadian Wind Energy Association. Retrieved on 2006-04-21.
23. ^ Canada's Current Installed Capacity (PDF). Canadian Wind Energy Association. Retrieved on 2006-12-11.
24. ^ Standard Offer Contracts Arrive In Ontario. Ontario Sustainable Energy Association (March 21, 2006). Retrieved on 2006-04-21.
25. ^ Call for Tenders A/O 2005-03: Wind Power 2,000 MW. Hydro-Québec. Retrieved on 2006-04-21.
26. ^ AeroTecture
27. ^ "Energy Technology Center: Project Architectural Wind", AeroVironment Inc, 2006.
28. ^ 'Micro' wind turbines are coming to town, CNET, February 10, 2006, Martin LaMonica
29. ^ Shashank Priya et al. "Piezoelectric Windmill: A novel solution to remote sensing", Japanese Journal of Applied Physics, v. 44 no. 3 p. L104-L107, 2005.
30. ^ Swift Turbines
31. ^ Better Generation: Swift Rooftop wind energy system discussion
32. ^ Motorwind
33. ^ Lucien Gambarota: Alternative energy pioneer, CNN, 16 April 2007
34. ^ Motorwind Turbines
35. ^ Helming, Troy (February 2, 2004). Uncle Sam's New Year's Resolution. RE Insider. Retrieved on 2006-04-21.
36. ^ Wind Power Increased by 27% in 2006. American Wind Energy Association (January 23, 2007). Retrieved on 2007-01-31.
37. ^ a b BWEA report on onshore wind costs
38. ^ http://www.eia.doe.gov/oiaf/ieo/pdf/0484(2006).pdf Energy Information Administration, "International Energy Outlook", 2006, p. 66.
39. ^ Fact sheet 4: Tourism
40. ^ http://www.windpower.org/en/stats/shareofconsumption.htm
41. ^ http://www.windpower.org/composite-1172.htm
42. ^ Archer, Cristina L.; Mark Z. Jacobson. Evaluation of global wind power. Retrieved on 2006-04-21.
43. ^ Archer, Cristina L.; Mark Z. Jacobson. Evaluation of global wind power. Retrieved on 2006-04-21.
44. ^ Global Wind Map Shows Best Wind Farm Locations. Environment News Service (May 17, 2005). Retrieved on 2006-04-21.
45. ^ Cohn, David (April 06, 2005). Windmills in the Sky. Wired News. Retrieved on 2006-04-21.
46. ^ Wind Plants of California's Altamont Pass
47. ^ [1]
48. ^ [2]
49. ^ Tackling Climate Change in the U.S.. American Solar Energy Society (January 2007). Retrieved on 2007-09-05.
51. ^ [3]
52. ^ http://www.power-technology.com/projects/tianhuangping/
53. ^ http://en.wikipedia.org/wiki/Pumped_storage_hydroelectricity
54. ^ https://www.cia.gov/library/publications/the-world-factbook/print/ch.html
55. ^ [4]
56. ^ [5]
57. ^ [6]
58. ^ [7]
59. ^ [8]
60. ^ [9]
61. ^ [10]
62. ^ [11]
64. ^ http://www.eirgrid.com/EirGridPortal/uploads/Publications/Wind%20Impact%20Study%20-%20main%20report.pdf ESB National Grid, "Impact of Wind Generation in Ireland on the Operation of Conventional Plant and the Economic Implications", 2004
65. ^ Annual Energy Review 2004 Report No. DOE/EIA-0384(2004). Energy Information Administration (August 15, 2005). Retrieved on 2006-04-21.
66. ^ url=http://www.ipcc.ch/SPM040507.pdf
67. ^ http://www.eoearth.org/article/Energy_return_on_investment_EROI_for_wind_energy
68. ^ Danish Wind Industry Association. Danis Wind Turbine Manufacturer's Association (December 1997). Retrieved on 2006-05-12.
69. ^ Net Energy Payback and CO2 Emissions from Wind-Generated Electricity in the Midwest. S.W.White & G.L.Klucinski — Fusion Technology Institute University of Wisconsin (December 1998). Retrieved on 2006-05-12.
70. ^ http://www.nature.com/nature/journal/v447/n7141/full/447126a.html
71. ^ RENEWABLE ENERGY — Wind Power’s Contribution to Electric Power Generation and Impact on Farms and Rural Communities (GAO-04-756) (PDF). United States Government Accountability Office (September 2004). Retrieved on 2006-04-21.
72. ^ Wind energy Frequently Asked Questions. British Wind Energy Association. Retrieved on 2006-04-21.
73. ^ Forest clearance for Meyersdale, Pa., wind power facility
74. ^ Birds. Retrieved on 2006-04-21.
75. ^ Lomborg, Bjørn (2001). The Skeptical Environmentalist. New York City: Cambridge University Press.
76. ^ (18 June 2005) "Wind turbines a breeze for migrating birds". New Scientist (2504): 21. Retrieved on 2006-04-21.
77. ^ Wind farms. Royal Society for the Protection of Birds (14 September 2005). Retrieved on 2006-04-21.
78. ^ The negative effects of windfarms on birds and other wildlife: articles by Mark Duchamp
79. ^ Developing Methods to Reduce Bird Mortality In the Altamont Pass Wind Resource Area
80. ^ Caution Regarding Placement of Wind Turbines on Wooded Ridge Tops (PDF). Bat Conservation International (4 January 2005). Retrieved on 2006-04-21.
81. ^ Arnett, Edward B.; Wallace P. Erickson, Jessica Kerns, Jason Horn (June 2005). Relationships between Bats and Wind Turbines in Pennsylvania and West Virginia: An Assessment of Fatality Search Protocols, Patterns of Fatality, and Behavioral Interactions with Wind Turbines (PDF). Bat Conservation International. Retrieved on 2006-04-21.
82. ^ Benefits of Wind Energy
83. ^ Wind turbine accident compilation, Caithness Windfarms Information Forum
84. ^ FAQ Hurricanes NOAA

## Wind power projects

The Altamont Pass is a mountain pass in Northern California, United States, located between Livermore in the Livermore Valley and Tracy in the San Joaquin Valley. ... The Cape Wind Project is a controversial proposed offshore wind farm on Horseshoe Shoal in Nantucket Sound off Cape Cod in Massachusetts (). If the project moves forward on schedule, it would become one of the first offshore wind farms in the United States. ... This article is about the U.S. state. ... Gharo Wind Power Plant is planned to be built at Gharo, Sindh, Pakistan. ... Offshore wind turbines near Copenhagen Some 20 per cent of Danish domestic electricity comes from wind [1]and Denmark is a leading wind power nation in the world. ... Spanish energy policy anticipates generating 30% of its electricity needs from renewable energy sources by 2010, with half of that amount coming from wind power in Spain. ... Erection of an Enercon E70-4 in Germany Germany is the worlds largest user of wind power with an installed capacity of 20,621MW in 2006, ahead of Spain which had an installed capacity of 11,615MW.[1] More than 18,000 wind turbines are located in the German... Wind power in Australia is clean and renewable and a typical wind turbine can meet the energy needs of up to 1000 homes. ... Wind power in the United Kingdom passed the milestone of 2 GW installed capacity on 9 February 2007, equivalent to two coal fired power stations, with the opening of the Braes ODoune wind farm, near Stirling. ... Map of available wind power over the United States. ... Wind, wave and tide make up more than 80% of Scotlands renewable energy potential. ...

Results from FactBites:

 Wind power - Wikipedia, the free encyclopedia (7814 words) Most modern wind power is generated in the form of electricity by converting the rotation of turbine blades into electrical current by means of an electrical generator. Wind power is used in large scale wind farms for national electrical grids as well as in small individual turbines for providing electricity in isolated locations. Wind power was the most rapidly-growing means of alternative electricity generation at the turn of the century and provides a valuable complement to large-scale base-load power stations.
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