Wind power

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Wind farm in Neuenkirchen, Dithmarschen, Germany.

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Wind power is the conversion of wind energy into more useful forms, usually electricity using wind turbines. In 2005, worldwide capacity of wind-powered generators was 58,982 megawatts; although it currently produces less than 1% of world-wide electricity use, it accounts for 23% of electricity use in Denmark, 6% in Germany and approximately 8% in Spain. Globally, wind power generation more than quadrupled between 1999 and 2005.

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. In windmills (a much older technology) wind energy is used to turn mechanical machinery to do physical work, like crushing grain or pumping water.

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 energy is ample, renewable, widely distributed, clean, and mitigates the greenhouse effect if used to replace fossil-fuel-derived electricity.

[edit] Cost and growth

The cost of wind-generated electric power has dropped substantially. Since 2004, according to some sources, the price in the United States is now lower than the cost of fuel-generated electric power, even without taking externalities into account.^[1][2][3] In 2005, wind energy cost one-fifth as much as it did in the late 1990s, and that downward trend is expected to continue as larger multi-megawatt turbines are mass-produced.^[4] A British Wind Energy Association report gives an average generation cost of onshore wind power of around 3.2 pence per kilowatt hour.^[5] Wind power is growing quickly, at about 38% in 2003,^[6] up from 25% growth in 2002. In the United States, as of 2003, wind power was the fastest growing form of electricity generation on a percentage basis.^[7]

Most major forms of electric 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 hydropower, 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 costs. The "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.

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.

[edit] Wind energy

Main article: Wind

An estimated 1% to 3% of energy from the Sun that hits the earth is converted into wind energy. This is about 50 to 100 times more energy than is converted into biomass by all the plants on earth through photosynthesis. 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 all through the earth's surface and atmosphere.

The origin of wind is simple. 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 powers a global atmospheric convection system reaching from the earth's surface to the stratosphere which acts as a virtual ceiling.

[edit] Wind variability and turbine power

A Darrieus wind turbine.

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.

The power P available in the wind is given by:

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.

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 energy 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.

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.

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.

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 of this is that wind energy is not dispatchable as for fuel-fired power plants; additional output cannot be supplied in response to load demand. — 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 as much as 35%. This compares to typical capacity factors of 90% for nuclear plants, 70% for coal plants, and 30% for oil plants.^[8] 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. — 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.^[1] 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

[edit] Turbine siting

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 greater. Obviously, meteorology plays an important part in determining possible locations for wind parks, though it has great accuracy limitations. Meteorological wind data is not usually sufficient for accurate siting of a large wind power project. An 'ideal' location would have a near constant flow of non-turbulent wind throughout the year and would not suffer too many sudden powerful bursts of wind. An important turbine siting factor is access to local demand or transmission capacity.

The wind blows faster at higher altitudes because of the reduced influence of drag of the surface (sea or land) and the reduced viscosity of the air. 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%).

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]}

[edit] Onshore

Wind turbines near Walla Walla in Washington

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 30 m 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.

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.

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). Local residents in a number of potential sites have strongly opposed the installation of wind farms, and political support has resulted in the blocking of construction of some installations.^[9]

[edit] Near-Shore

Near-Shore turbine installations are generally considered to be within a zone that is on land three kilometers of a shoreline and on water within ten kilometers of land. Wind speeds in these zones share wind speed characteristics of both onshore wind 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 amongst several others.

Sea shores also tend to be windy areas and good sites for turbine installation, because a primary source of wind is convection from the differential heating and cooling of land and sea over the course of day and night. Winds at sea level carry somewhat more energy than winds of the same speed in mountainous areas because the air at sea level is more dense.

Near-shore wind farm siting can sometimes be highly controversial as coastal sites are often picturesque and environmentally sensitive (for instance, having substantial bird life). Local residents in a number of potential sites have strongly opposed the installation of wind farms due to visual aesthetic concerns.

[edit] Offshore

Wind blows briskly and smoothly over water since there are no obstructions. Offshore wind development zones are generally considered to be ten kilometers or more from land. The large and slow turning turbines of this offshore wind farm at Middlegrunden near Copenhagen take advantage of the moderate yet constant breezes here.

Offshore wind turbines cause less aesthetic controversy since they often cannot be seen from the shore. Offshore wind development zones are generally considered to be ten kilometers or more from land. Because there are fewer obstacles and stronger winds, such turbines also don't need to be built as high into the air. Capacity factors (utilisation rates) are considerably higher than for onshore and near-shore locations. However, offshore turbines are in many cases less accessible and offshore conditions in oceans or seas can be harsh, abrasive, and corrosive, thereby increasing the costs of operation and maintenance compared to onshore turbines. Offshore developments in fresh-water areas such as the Great Lakes do not have the abrasive and corrosive challenges of salt water development sites and some locations have extremely strong winds. The recently announced Trillium Power Wind 1 site in Lake Ontario (approximately 17 to 25 kilometers from shore) is projected to generate approximately 710MW when in service by 2011. Generaly, ice free locations in Lake Ontario and southern Lake Michigan may be easier to service year round than other Great Lake locations that freeze over during the Winter.

In areas with extended shallow continental shelves and sand banks (such as Denmark), turbines are reasonably easy to install, and give good service. At the site shown(left), the wind is not especially strong but is very consistent. The largest offshore wind turbines in the world are two 5.0MW REpower turbines installed at the Beatrice Wind Farm approximately 25km offshore from Aberdeen, Scotland. Until recently, the largest installation were seven 3.6 MW rated machines off the east coast of Ireland about sixty kilometres south of Dublin. The turbines are located on a sandbank approximately ten kilometres from the coast that has the potential for the installation of 500 MW of generation capacity.

As of 2006, the largest offshore wind farm by power production is the Nysted Offshore Wind Farm at Rødsand, located about ten kilometres south of Nysted and thirteen kilometres west of Gedser Denmark. The wind farm consists of seventy two turbines of 2.3 MW, which produces 165.6 MW of power at rated wind speed.^[10] Three offshore wind farms in the United Kingdom are currently operating, North Hoyle (30 x 2 MW), Scroby Sand (30 x 2 MW) and Kentish flat (30 x 3 MW). Another offshore wind farm, Barrow (30 x 3 MW), is under construction. Under the energy policy of the United Kingdom further offshore facilities are feasible and expected by the year 2010.

The proposed Cape Wind development in the United States and the Havsul development in Norway have not been without siting controversies. Although they have have in some cases been referred to as offshore locations they are actually located within ten kilometers of land and are therefore in near-shore development zones.

[edit] Airborne

Main article: Airborne wind turbine

Wind turbines might also be flown in high speed winds at altitude,^[11] although no such systems currently exist in the marketplace. An Ontario company, Magenn Power, Inc., is attempting to commercialize tethered aerial turbines suspended with helium^[12]

[edit] Vertical-axis turbines

A prototype of vertical-axis wind turbine is the Italian project called "Kitegen". It is an innovative plan (still in phase of construction) that consists in 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. According to its developers, a one GigaWatt installation will be 1/40 the cost of the corresponding nuclear powerplant.

The project kitegen has received 15 million euro financing from the Italian state. It will begun with a 1 MW prototype and then with the planning of a power kitegen of 20 MW. ^{[citation needed]}

[edit] Utilization

[edit] Large scale

There are many thousands of wind turbines operating, with a total capacity of 58,982 MW of which Europe accounts for 69% (2005). The average output of one megawatt of wind power is equivalent to the average consumption of about 160 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 1999 and 2005. 90% 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. By 2010, World Wind Energy Association expects 120,000 MW to be installed worldwide.^[13]

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 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.

Wind accounts for 1% of the total electricity production on a global scale (2005). Germany is the leading producer of wind power with 32% of the total world capacity in 2005 (6% 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 16,000 wind turbines, mostly in the north of the country — including three of the biggest in the world, constructed by the companies Enercon (4.5 MW), Multibrid (5 MW) and Repower (5 MW). Germany's Schleswig-Holstein province generates 25% of its power with wind turbines.

Spain and the United States 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.^[1] Wind power could grow by 50% in the U.S. in 2006.^[14]

India ranks 4th in the world with a total wind power capacity of 5,340 MW. Wind power generates 3% of all electricity produced in India. The World Wind Energy Conference in New Delhi in November 2006 will give additional impetus to the Indian wind industry.^[13] 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. The windfarm near Muppandal, India, provides an impoverished village with energy for work.^{[15] [16]}

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.^{[citation needed]}

Another growing market is Brazil, with a wind potential of 143 GW.^[17] The federal government has created an incentive program, called Proinfa,^[18] 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.

View of wind farm near Muppandal in India

Over the 6 years from 2000-2005, Canada experienced rapid growth of wind capacity — moving from a total installed capacity of 137 MW to 943 MW, and showing a growth rate of 38% and rising.^[19] Particularly rapid growth has been seen in 2006, with total capacity growing to 1,451 MW by December, 2006, doubling the installed capacity from the 684 MW at end-2005.^[20] This growth was fed by provincial measures, including installation targets, economic incentives and political support. For example, the government of the Canadian province of Ontario announced on 21 March 2006 that it will introduce a feed-in tariff for wind power, referred to as 'Standard Offer Contracts', which may boost the wind industry across the entire country.^[21] In the Canadian province of Quebec, the state-owned hydroelectric utility plans beside current wind farm projects to purchase an additional 2000 MW by 2013.^[22]

[edit] 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.

Wind turbines have been used for household electricity generation in conjunction with battery storage over many decades in remote areas. Household generator units of more than 1 kW are now functioning in several countries.

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.

Wind turbines range from small four hundred watt generators for residential use to several megawatt machines for wind farms and offshore. The small ones 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.

In urban locations, where it is difficult to obtain 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.

Small-scale wind power in rural Indiana.

Small scale turbines are available that are approximately 7 feet (2 m) in diameter and produce 900 watts. Units are lightweight, e.g. 16 kilograms (35 lbs), allowing rapid response to wind gusts typical of urban settings and easy mounting much like a television antenna. It is claimed that they are inaudible even a few feet under the turbine.^{[citation needed]} Dynamic braking regulates the speed by dumping excess energy, so that the turbine continues to produce electricity even in high winds. The dynamic braking resistor may be installed inside the building to provide heat (during high winds when more heat is lost by the building, while more heat is also produced by the braking resistor). The proximal location makes low voltage (12 volt, or the like) energy distribution practical. An additional benefit is that owners become more aware of electricity consumption, possibly reducing their consumption down to the average level that the turbine can produce.

According to 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.^[13]

Small wind turbines have a fundamental advantage over large wind turbines: this is the square-cube law. The wind capture or swept area of turbines is proportional to the square of the blade radius, but the volume, and therefore mass, of turbines is (approximately) proportional to the cube of the blade radius. Design and materials improvements have made both large and small turbines lighter for given output. Larger turbines have the advantage of commodity pricing, lower land footprint per output, and lower cost of electronics and minor hardware as a percentage of unit cost. If the price of small turbines can be lowered to near materials cost, with the barest premium for design and labor, then, with their lower mass per output, they can compete favorably.

[edit] Wind power: major 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

[edit] 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.

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%. 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 consumption^[23] and a recent poll of Danes show that 90% want more wind power installed.^[24]

[edit] Theoretical potential

Wind's long-term theoretical potential is much greater than current world energy consumption. The most comprehensive study to date^[25] found the potential of wind power on land and near-shore to be 72 TW (~54,000 Mtoe), or over five 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). This 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 wheeling power over large distances, or of switching to wind power.

To determine the more realistic technical potential it is essential 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. Even so, the potential comfortably exceeds current world electricity demand.

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.

Offshore resources experience mean wind speeds ~90% greater than that of land, so offshore resources could contribute about seven times more energy than land.^[26][27] This number could also increase with higher altitude or airborne wind turbines.^[28]

To meet energy demands worldwide in the future in a sustainable way, a much larger number of turbines than have been currently installed will be required. Naturally this will affect more people and wildlife habitat. See the section below on ecology and pollution.

[edit] 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.^[29] 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.

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. Significantly, carbon dioxide, a greenhouse gas produced when using fossil fuels for electricity production, may impose costs on society in the form of global warming. Few mechanisms currently exist to impose (or internalise) this external cost 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.

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 may debate the level of subsidies required or existing, the "cost" of pollution externalities, and the uncertain financial returns to wind projects — that is, the all-in cost of wind energy compared to other technologies. 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. If a comparison is made on real production costs, wind energy may be competitive compared to many other sources. If the full costs (environmental, health, etc.) are taken into account, wind energy would be competitive in many more cases. Furthermore, wind energy costs are continuously decreasing due to technology development and scale enlargement.
• Nuclear power plants receive special immunity from the disasters they may cause, which prevents victims from recovering the cost of their continued health care from those responsible, even in the case of criminal malfeasance. In many cases, nuclear plants are owned directly by governments or substantially supported by them. In both cases, nuclear plants benefit from a lower cost of capital and lower perceived risk, as governments take on the risk charge directly. This is a form of indirect subsidy, although the size of this subsidy is difficult to ascertain precisely.
• To compete with traditional sources of energy, wind power often receives financial incentives. In the United States, wind power receives a tax credit currently of 1.9 cents per kilowatt-hour produced, with 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 tax credits and other incentives for wind turbine construction.
• 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.
• 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.
• 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. Further reductions in the cost of wind energy can be expected 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 going forward.
• 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 they produce when prices are higher. 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 and wind farm output is highly correlated, overall revenues would be lower. In economic terms, the marginal revenue of the wind sector as penetration increases may diminish.

[edit] Intermittency and variability

Main article: Intermittent Power Sources

Electricity generated from wind power can be highly variable on several different time scales: from hour-to-hour, daily, and seasonally; although annual variation exists, it is not as significant. This 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.

Paradoxically whilst the negative effects of intermittency has to be considered in the economics of power generation, an unacknowledged positive attribute is that many intermittent resources are highly reliable, in fact much more reliable than despatchable sources. For example, it would require around 400 × 3MW wind turbines at 40% utilisation to deliver the same annual energy as a 660 MW steam turbine at 70% utilisation. Whilst two 660 MW turbines can fail at any second with no warning, necessitating the provision of 1200 MW of standby / spinning reserve, 400 × 3 MW wind turbines cannot all suffer a simaltaneous fault, and neither can the wind instantaneously drop to zero.

Grid operators routinely control the supply of electricity by cycling generating plants on or off in 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 already is widespread.

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 up to 20% (stated as the proportion of wind nameplate capacity to peak energy demand) may be incorporated with minimal difficulty. 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%, and only Denmark is in the range of this 20% penetration level. Discussion about the feasibility of wind penetration beyond the level of 20% is, at present, largely theoretical.

[edit] Ecology and pollution

[edit] CO₂ emissions and pollution

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 straightforward. Wind power's ability to reduce pollution and greenhouse gas emissions will depend on the amount of wind energy produced, and hence scalability.

• 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^[30]) 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^[5] 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 state that the desired mitigation goals can be achieved at lower cost and to a greater degree by continued improvements in general efficiency — in building, manufacturing, and transport — than by wind power.^[31]
• 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. ^[32]
• 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.^[33] 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.^[34]
• 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.

[edit] 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 impact the numbers of some bird species, conventionally fueled power plants could wipe out hundreds or even thousands of the world's species through climate change, acid rain, and pollution.
• Unlike fossil fuel or nuclear power stations, which circulate or evaporate large amounts of water for cooling, wind turbines do not need water to generate electricity.

[edit] 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 discernable 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. 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 sighted 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.

A wind turbine at Greenpark, Reading, England

[edit] 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.^[35] 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.^[36] 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.^[37]
• 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 wind farm that produces the energy equivalent of a conventional 2 GW 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 and avoid known shipping channels. However, that is generally not the norm for most offshore locations. 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.

[edit] 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.^[38] 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.^[39] 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,^[40] 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."^[41] 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.^[42] 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 travelled around offshore wind farms. A Danish survey in 2005 (Biology Letters 2005:336) showed that less than 1% of migrating birds passing an oshore 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^[43] 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.
• 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.^[44] 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.^[45] 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.^[46] 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.

[edit] Aesthetics

• 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.[1]

Wind power is nothing new. Windmills at La Mancha, Spain.

• Improvements in blade design and gearing have quietened modern turbines to the point where a normal conversation can be held underneath one.
• Newer wind farms have more widely spaced turbines due to the greater power of the individual wind turbines, and so look less cluttered.
• The aesthetics of onshore and near-shore wind turbines have been compared favourably 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.

[edit] See also

Wikimedia Commons has media related to: Wind power

[edit] Power generation

• Fossil fuel power and petro-free
• Hydropower
• Nuclear Power
• Solar power and nuclear residues.
• Solar updraft tower
• Steam engine

[edit] Green energy

• Green energy
• Green tax shift
• Grid energy storage
• Renewable energy
• Nuclear power phase-out
• Wind
• Windmill
• Wind farm
• Wind turbine

[edit] By country

• Wind power in the United Kingdom

[edit] References

1. ^ ^{a b c} Mitchell, Chris (March 23, 2006). Price of Wind-Generated Electricity Plummeting. Retrieved on 2006-04-21.
2. ^ Chakrabarty, Gargi (March 27, 2004). Powering up. Rocky Mountain News. Retrieved on 2004-04-05. (Internet Archive version)
3. ^ E-Letter responses to: The Real Cost of Wind Energy. Science. Retrieved on 2006-04-21.
4. ^ Helming, Troy (February 2, 2004). Uncle Sam's New Year's Resolution. RE Insider. Retrieved on 2006-04-21.
5. ^ ^{a b} BWEA report on onshore wind costs
6. ^ Alternate Power: A Change Is In The Wind. Business Week (July 4, 2005). Retrieved on 2006-04-21.
7. ^ Renewable Energy Trends 2003 (PDF). DOE/EIA (July 2004). Retrieved on 2006-04-21.
8. ^ Nuclear Energy Institute. Nuclear Facts. Retrieved on July 23rd, 2006.
9. ^ Hogan, Jesse. "Fury over wind farm decision", The Age, 2006-04-05. Retrieved on 2006-08-18.
10. ^ Nysted offshore wind farm. E2. Retrieved on 2006-06-10.
11. ^ David Cohn. Windmills in the Sky. Wired News: Windmills in the Sky. San Francisco: Wired News. Retrieved on July 28, 2006.
12. ^ Magenn Power Inc. corporate website. Retrieved on August 18, 2006.
13. ^ ^{a b c d} the World Wind Energy Association (WWEA) web site. Retrieved on 2006-04-21.
14. ^ Aslam, Abid (31 March 2006). Problem: Foreign Oil, Answer: Blowing in the Wind?. OneWorld US. Retrieved on 2006-04-21.
15. ^ Tapping the Wind — India (February 2005). Retrieved on 2006-10-28.
16. ^ Watts, Himangshu (November 11 2003). Clean Energy Brings Windfall to Indian Village. Reuters News Service. Retrieved on 2006-10-28.
17. ^ Atlas do Potencial Eólico Brasileiro. Retrieved on 2006-04-21.
18. ^ Eletrobrás — Centrais Elétricas Brasileiras S.A — Projeto Proinfa. Retrieved on 2006-04-21.
19. ^ Wind Energy: Rapid Growth (PDF). Canadian Wind Energy Association. Retrieved on 2006-04-21.
20. ^ Canada's Current Installed Capacity (PDF). Canadian Wind Energy Association. Retrieved on 2006-12-11.
21. ^ Standard Offer Contracts Arrive In Ontario. Ontario Sustainable Energy Association (March 21, 2006). Retrieved on 2006-04-21.
22. ^ Call for Tenders A/O 2005-03: Wind Power 2,000 MW. Hydro-Québec. Retrieved on 2006-04-21.
23. ^ http://www.windpower.org/en/stats/shareofconsumption.htm
24. ^ http://www.windpower.org/composite-1172.htm
25. ^ Archer, Cristina L.; Mark Z. Jacobson. Evaluation of global wind power. Retrieved on 2006-04-21.
26. ^ Archer, Cristina L.; Mark Z. Jacobson. Evaluation of global wind power. Retrieved on 2006-04-21.
27. ^ Global Wind Map Shows Best Wind Farm Locations. Environment News Service (May 17, 2005). Retrieved on 2006-04-21.
28. ^ Cohn, David (Apr 06, 2005). Windmills in the Sky. Wired News. Retrieved on 2006-04-21.
29. ^ Wind Plants of California's Altamont Pass
30. ^ Annual Energy Review 2004 Report No. DOE/EIA-0384(2004). Energy Information Administration (August 15, 2005). Retrieved on 2006-04-21.
31. ^ Wind and the Mitigation of CO2 Emissions — The Global Picture.}
32. ^ http://www.eoearth.org/article/Energy_return_on_investment_EROI_for_wind_energy
33. ^ Danish Wind Industry Association. Danis Wind Turbine Manufacturer's Association (December 1997). Retrieved on 2006-05-12.
34. ^ 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.
35. ^ 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.
36. ^ Wind energy Frequently Asked Questions. British Wind Energy Association. Retrieved on 2006-04-21.
37. ^ Forest clearance for Meyersdale, Pa., wind power facility
38. ^ Birds. Retrieved on 2006-04-21.
39. ^ Lomborg, Bjørn (2001). The Skeptical Environmentalist. New York City: Cambridge University Press.
40. ^ (18 June 2005) "Wind turbines a breeze for migrating birds". New Scientist (2504): 21. Retrieved on 2006-04-21.
41. ^ Wind farms. Royal Society for the Protection of Birds (14 September 2005). Retrieved on 2006-04-21.
42. ^ The negative effects of windfarms on birds and other wildlife: articles by Mark Duchamp
43. ^ Developing Methods to Reduce Bird Mortality In the Altamont Pass Wind Resource Area
44. ^ Royal Society for the Protection of Birds: Wind farm strikes at eagle stronghold
45. ^ Caution Regarding Placement of Wind Turbines on Wooded Ridge Tops (PDF). Bat Conservation International (4 January 2005). Retrieved on 2006-04-21.
46. ^ 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.

[edit] External links

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[edit] Technical

• Wind Power in the UK — A Report by the Sustainable Development Commission
• Global wind power (includes map)
• Wind Power Impacts on Electric Power System Operating Costs by the U.S. National Renewable Energy Laboratory (2004)
• Average annual wind power map for the U.S.
• Wind Atlases of the World – The World of Wind Atlases – Lists of wind atlases and wind surveys from all over the world
• Database of Wind Characteristics – Wind data for wind (turbine) design and wind resource assessment and siting
• Discussion of application of wind turbines in cold climates

[edit] Political

• Asociación Argentina de Energía Eólica — AAEE — Argentine Wind Energy Association, (Argentina)
• World Wind Energy Association WWEA
• German Wind Energy Association BWE
• Spanish Wind Energy Association (Asociación Empresarial Eólica)
• The British Wind Energy Association
• American Wind Energy Association
• African Wind Energy Association — AfriWEA is a non-profit organisation formed in 2002 to encourage manufacturers, developers, governments, renewable energy owners and individuals to promote and support wind energy development on the African continent
• European Wind Energy Association Extensive information and myth debunking in the report: windenergy the facts.
• Canadian Wind Energy Association
• Alliance to Protect Nantucket Sound Citizens group opposed to plans for USA's first offshore wind facility.
• Capewind — Website of USA's first offshore wind facility.
• Country Guardian — A UK NGO opposed to the construction of wind turbines.
• Windustry — A non-profit organization working to increase wind energy opportunities for rural landowners and communities.
• National Wind Watch — A US coalition of citizens and grassroots groups to promote knowledge and raise awareness of the damaging impacts of industrial wind turbine development.
• Industrial Wind Energy Opposition — Resources for debunking claims, documenting ill effects, and fighting the spread of industrial wind power
• Iberica 2000.org — On the serious impact of wind farms on birds.
• "We Must Increase Our Gust" — On wind power's ability to replace other sources, with lively forum discussion.
• "Shooting Down the Breeze" — On wind power industry's ambivalent concern about wildlife impacts, also with lively forum discussion.
• Wind Works — An extensive personal site on windpower. Nuanced pro wind energy.
• yes2wind — A website by Greenpeace, Friends of the Earth and the WWF in support of wind energy in support of the wind industry.
• ExternE — The European research project about the external costs of energy production in general.
• Wind systems — On the site of the Australian Greenhouse Office.
• POWER — Pushing Offshore Wind Energy Regions — POWER is an European Interreg project which establishes a discussion platform and a support of European regions in the development of offshore-windenergy projects.

[edit] Wind power projects

• Altamont Pass
• Austin Energy's GreenChoice Program
• Cape Wind (Massachusetts)
• Gharo Wind Power Plant in Pakistan
• Database of projects throughout the United States
• First Community Based Project in Hull, MA
• Trillium Power in Ontario, Canada
• Judith Gap Wind Farm (Montana) now on-line
• Kite Wind Generator, (Italy)
• Mawson Station — High Penetration (>90%) Wind Diesel at Mawson Station in Antarctica.

[edit] Academic institutions

• Endowed Chair of Wind Energy – Stuttgart University
• Wind Energy Department – Risø National Laboratory
• Wind Energy at Appalachian State University – Boone, North Carolina