Environmental impact of wind power

Livestock ignore wind turbines, and continue to graze as they did before wind turbines were installed.

Compared to the environmental effects of traditional energy sources, the environmental effects of wind power are relatively minor. Wind power consumes no fuel, and emits no air pollution, unlike fossil fuel power sources. The energy consumed to manufacture and transport the materials used to build a wind power plant is equal to the new energy produced by the plant within a few months of operation. Garrett Gross, a scientist from UMKC in Kansas City, Missouri states, "The impact made on the environment is very little when compared to what is gained." The initial carbon dioxide emission from energy used in the installation is "paid back" within about 9 months of operation for offshore turbines.

Danger to birds and bats is often the main complaint against the installation of a wind turbine. However, 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, and especially the environmental impacts of using non-clean power sources. Bat species appear to be at risk during key movement periods. 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. While a wind farm may cover a large area of land, many land uses such as agriculture are compatible, with only small areas of turbine foundations and infrastructure made unavailable for use.

Aesthetics have also been an issue at times. The Massachusetts Cape Wind project was delayed for years mainly because of aesthetic concerns. Locals believe that the Ardrossan Wind Farm in Scotland has enhanced the area, saying that the turbines are impressive looking and bring a calming effect to the town.

Carbon dioxide emissions and pollution

Wind power consumes no fuel for continuing operation, and has no emissions directly related to electricity production. Operation does not produce carbon dioxide, sulfur dioxide, mercury, particulates, or any other type of air pollution, as do fossil fuel power sources. Wind power plants consume resources in manufacturing and construction. 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 initial carbon dioxide emissions "pay back" is within about 9 months of operation for off shore turbines.

Wind power may affect emissions at fossil-fuel plants used for reserve and regulation:

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.

A study by the Irish national grid stated 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 0.33 to 0.59 tonnes of CO₂ per MWh.

As yet, however, no study has been done to establish the actual reduction of CO₂ and other emissions due to existing wind energy installations.

Net energy gain

The energy consumed to manufacture and transport the materials used to build a wind power plant is equal to the new energy produced by the plant within a few months of operation. Garrett Gross, a scientist from UMKC in Kansas City, Missouri states, "The impact made on the environment is very little when compared to what is gained." The initial carbon dioxide emission from energy used in the installation is "paid back" within about 9 months of operation for off shore turbines. Any practical large-scale energy source must replace the energy used in its construction. 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. EROI is strongly proportional to turbine size, and larger late-generation turbines are at the high end of this range, at or above 35. Since energy produced is several times energy consumed in construction, there is a net energy gain. The energy used for construction is produced by the wind turbine within a few months of operation.

Ecological footprint

Over a dozen wind turbines are visible on the horizon near an open-pit coal mine in Germany

File:MarsHillConstruction.jpg

Blasting and clearance of several acres were necessary to install a wind turbine at the north end of Mars Hill, Maine.

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. However, leaking lubricating oil or hydraulic fluid running down turbine blades may be scattered over the surrounding area, in some cases contaminating drinking water areas.

Wind turbines avoid the sometimes drastic ecological impact of mining techniques to extract fossil fuels, such as the open-pit mining used for shallow coal deposits and oil sands, and the sometimes extensive water pollution that results from processing low-grade fossil fuels.

Projects such as the Black Law Wind Farm have received wide recognition for its contribution to environmental objectives, including praise from the Royal Society for the Protection of Birds, who said that the scheme was not only improving the landscape in a derelict opencast mining site, but also benefiting a range of wildlife in the area, with an extensive habitat management projects covering over 14 square kilometres.

Climate change

A wind turbine at Greenpark, Reading, England, producing electricity for around one thousand homes

One study reports simulations that show detectable changes in global climate for very high wind farm usage, on the order of 10% of the world's land area. In a similar way, there are concerns of micro-climate change, in particular for urban areas nearby, due to changed airflow and reduced wind power.

Land use

To reduce losses caused by interference between turbines, a wind farm requires roughly 0.1 km² (0.039 sq mi) of unobstructed land per megawatt of nameplate capacity. A 200 MW wind farm might extend over an area of approximately 20 km² (7.7 sq mi).

Clearing of wooded areas is often unnecessary. Farmers commonly lease land to companies building wind farms. In the U.S., farmers may receive annual lease payments of two thousand to five thousand dollars per turbine. 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. Trenches for buried power lines and rights of way for suspended lines are other impacts on the land. Turbines can be sited on unused land in techniques such as center pivot irrigation. The clearing of trees for about 5 acres around tower bases is done for installation sites on mountain ridges, such as in the northeastern U.S.

Turbines are not generally installed in urban areas. Buildings interfere with wind, turbines must be sited a safe distance ("setback") from residences in case of failure and due to noise, and the value of land is high. However, there are a few notable exceptions. Toronto Hydro has built a lake shore demonstration project, and Steel Winds is a 20 MW urban project south of Buffalo, New York. Both of these projects are in urban locations, but benefit from being on uninhabited lake shore property.

Offshore locations use no land and avoid known shipping channels. 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.

Impact on wildlife

Birds

Danger to birds is often the main complaint against the installation of a wind turbine. However, 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, the introduction of feral and roaming domestic cats, 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. In the United States, turbines kill 70,000 birds per year, compared to 80,000 killed by aircraft, 57 million killed by cars, 97.5 million killed by collisions with plate glass, and hundreds of millions killed by cats. An article in Nature stated that each wind turbine kills an average of 4.27 birds per year.

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." It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy. The National Audubon Society in the U.S. takes a similar position, broadly supporting wind power to help mitigate global warming, while cautioning against siting wind farms in areas especially important to birds and other affected wildlife.

In some cases, the mere presence of wind turbines or transmission towers can affect threatened species, by restricting their range, thus fragmenting breeding populations. The U.S. Fish and Wildlife Service has issued voluntary guidelines for the siting of wind energy facilities in the United States. These guidelines make recommendations regarding siting which include avoiding placement in 1) areas documented as the location of any species protected under the Endangered Species Act, 2) in local bird migration pathways or areas where birds concentrate, 3) near landscape features that attract raptors, 4) in a configuration that is likely to cause bird mortality, and 5) where fragmentation of large contiguous tracts of wildlife habitat will occur as a result of turbine placement. The wind industry is resisting such regulations.

Some paths of bird migration, particularly for birds that fly by night, are unknown. A study suggests that migrating birds may avoid the large turbines, at least in the low-wind non-twilight conditions studied. A Danish 2005 (Biology Letters 2005:336) study showed that radio tagged migrating birds traveled around offshore wind farms, with 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.

The National Environmental Research Institute of Denmark developed a Thermal Animal Detection System (TADS), a heat-activated infrared video camera mounted on a wind turbine that records bird collisions. The first results, released in 2007, found "seabirds to be remarkably adept at avoiding offshore installations".

An early wind farm in the Tehachapi Mountains of California

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 birds annually (881 to 1,300 of which were birds of prey). According to a study by the National Research Council, the relatively high bird kills at Altamont Pass are due to the large numbers of older wind turbines there. Many of these older turbines have lower hub heights, shorter rotor diameters which spin at high RPM, and tighter turbine spacing than are typical for newer wind farms. Older turbines often have lattice towers that attract nesting birds, in contrast to newer turbines with tubular steel towers whose smooth exteriors provide no nesting purchase.

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 turbine blades.

A wind farm in Norway's Smøla islands is reported to have affected a colony of sea eagles, according to the British Royal Society for the Protection of Birds. Turbine blades killed ten of the birds between August 2005 and March 2007, including three of the five chicks that fledged in 2005. Nine of the 16 nesting territories appear to have been abandoned. Norway is regarded as the most important place for white-tailed eagles.

A study published in 2008 found that wind turbines on European farmland have only minimal effects on wintering farmland birds, and found no evidence that future expansion of wind farms on European farmland will be detrimental to birds, but cautioned that more work is needed.

Bats

The numbers of bats killed by existing onshore and near-shore facilities has troubled bat enthusiasts. 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. This study suggests some onshore and near-shore sites may be particularly hazardous to local bat populations and more research is 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, red bat, and the silver-haired bat 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. It has been suggested that bats are attracted to these structures in search of roosts. Offshore wind sites 10 km (6 mi) or more from shore do not interact with bat populations.

Bats may be injured by direct impact with turbine blades, towers, or transmission lines. Recent research shows that bats may also be killed when suddenly passing through a low air pressure region surrounding the turbine blade tips. The low pressure damages the bat's lungs, called barotrauma. Birds have more rigid lungs and are not affected by the low pressure zone.

In October 2008, the Bats and Wind Energy Cooperative began a study to test the effect on bats of stopping wind farm operations during low wind conditions, when bats are most active.

Fish

In Ireland, construction of a wind farm caused pollution feared to be responsible for wiping out vegetation and fish stocks in Lough Lee. A separate landslide is thought to have been caused by wind farm construction, and has killed thousands of fish by polluting the local rivers with sediment.

Offshore

Many offshore wind farms are being built in UK waters. In January 2009, a comprehensive government environmental study of coastal waters in the United Kingdom concluded that there is scope for between 5,000 and 7,000 offshore wind turbines to be installed without an adverse impact on the marine environment. The study – which forms part of the Department of Energy and Climate Change's Offshore Energy Strategic Environmental Assessment – is based on more than a year's research. It included analysis of seabed geology, as well as surveys of sea birds and marine mammals.

Safety

Operation of any utility-scale energy conversion system presents safety hazards. Wind turbines do not consume fuel or produce pollution during normal operation, but still have hazards associated with their construction and operation.

There have been at least 40 fatalities due to construction, operation, and maintenance of wind turbines, including both workers and members of the public, and other injuries and deaths attributed to the wind power life cycle. Most worker deaths involve falls or becoming caught in machinery while performing maintenance inside turbine housings. Blade failures and falling ice have also accounted for a number of deaths and injuries. Deaths to members of the public include a parachutist colliding with a turbine and small aircraft crashing into support structures. Other public fatalities have been blamed on collisions with transport vehicles and motorists distracted by the sight and shadow flicker of wind turbines along highways.

When a turbine's brake fails, the turbine can spin freely until it disintegrates or catches fire. This is mitigated in most modern designs by aero brakes, variable pitch blades, and the ability to turn the nacelle to face out of the wind. Turbine blades may fail spontaneously due to manufacturing flaws. Lightning strikes are a common problem, also causing rotor blade damage and fires. When ejected, pieces of broken blade and ice can be thrown hundreds of meters away. Although no member of the public has been killed by a malfunctioning turbine, there have been close calls, including injury by falling ice. Large pieces of debris, up to several tons, have dropped in populated areas, residential properties, and roads, damaging cars and homes.

Often turbine fires cannot be extinguished because of the height, and are left to burn themselves out. In the process, they generate toxic fumes and can scatter flaming debris over a wide area, starting secondary fires below. Several turbine-ignited fires have burned hundreds of acres of vegetation each, and one burned 800 square kilometres (200,000 acres) of Australian National Park.

Electronic controllers and safety sub-systems monitor many different aspects of the turbine, generator, tower, and environment to determine if the turbine is operating in a safe manner within prescribed limits. These systems can temporarily shut down the turbine due to high wind, electrical load imbalance, vibration, and other problems. Recurring or significant problems cause a system lockout and notify an engineer for inspection and repair. In addition, most systems include multiple passive safety systems that stop operation even if the electronic controller fails.

Wind power proponent and author Paul Gipe estimated in Wind Energy Comes of Age that the mortality rate for wind power from 1980–1994 was 0.4 deaths per terawatt-hour. Paul Gipe's estimate as of end 2000 was 0.15 deaths per TWh, a decline attributed to greater total cumulative generation.

By comparison, hydroelectric power was found to have a fatality rate of 0.10 per TWh (883 fatalities for every TW·yr) in the period 1969–1996. This includes the Banqiao Dam collapse in 1975 that killed thousands. Although the wind power death rate is higher than some other power sources, the numbers are necessarily based on a small sample size. The apparent trend is a reduction in fatalities per TWh generated as more generation is supplied by larger units.

Aesthetics

Windmills at La Mancha, Spain, made famous by the 1605 novel Don Quixote, are a national treasure.

Historical experience of noisy and visually intrusive wind turbines may create resistance to the establishment of land-based wind farms. Residents near turbines may complain of "shadow flicker" caused by rotating turbine blades. Wind towers require aircraft warning lights, which create bothersome light pollution. Complaints about these lights have caused the FAA to consider allowing fewer lights per turbine in certain areas.

These effects may be countered by changes in wind farm design.

Modern large turbines have low sound levels at ground level. For example, in December 2006, a Texas jury denied a noise pollution suit against FPL Energy, after the company demonstrated that noise readings were not excessive. The highest reading was 44 decibels, which was characterized as about the same level as a 10 mile/hour (16 km/h) wind. In the United States, roadway noise contributes more to environmental noise exposure than any other noise source.

Newer wind farms have larger, more widely spaced turbines, and so look less cluttered than old installations.

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). Wind farms may be close to scenic or otherwise undeveloped areas. Constructing offshore wind developments at least 10 km from shore may reduce this concern. Aesthetic issues are subjective, however. Some people find wind farms pleasant and optimistic, or symbols of energy independence and local prosperity, and recognize that perceptions of what is "beautiful" in landscape is subject to change. Other visually obtrusive engineering works, such as superhighways and skyscrapers, are no longer generally considered to be visually alarming after decades of coexisting with people.

While some tourism officials predict wind farms will damage tourism, some wind farms have themselves become tourist attractions, with several having visitor centers at ground level or even observation decks atop turbine towers.

Community debate

The wind turbines at Findhorn Ecovillage which make the community a net exporter of electricity.

U.S. Landowners typically receive $3,000 to $5,000 per year in rental income from each wind turbine, while farmers continue to grow crops or graze cattle up to the foot of the turbines.

Wind turbines such as these, in Cumbria, England, have been opposed for a number of reasons, including aesthetics, by some sectors of the population.

Shiloh Wind Power Plant. The surrounding land is used for sheep grazing and growing hay.

Many wind power companies work with local communities to reduce environmental and other concerns associated with particular wind farms. In other cases there is direct community ownership of wind farm projects. Appropriate government consultation, planning and approval procedures also help to minimize environmental risks. Some people may still object to wind farms but, according to The Australia Institute, their concerns should be weighed against the need to address the threats posed by climate change and the opinions of the broader community. Surveys of public attitudes across Europe and in many other countries show strong public support for wind power.

In Germany, for example, hundreds of thousands of people have invested in citizens' wind farms across the country and thousands of small and medium sized enterprises are running successful businesses in a new sector that in 2008 employed 90,000 people and generated 8 percent of Germany's electricity. Wind power has gained very high social acceptance in Germany.

In America, wind projects are reported to boost local tax bases, helping to pay for schools, roads and hospitals. Wind projects also revitalize the economy of rural communities by providing steady income to farmers and other landowners.

The Intrepid Wind Farm, in Iowa, is an example of one wind farm where the environmental impact of the project has been minimized through consultation and co-operation:

"Making sure the wind farm made as gentle an environmental impact as possible was an important consideration. Therefore, when MidAmerican first began planning the Intrepid site, they worked closely with a number of state and national environmental groups. Using input from such diverse groups as the Iowa Department of Natural Resources, the Nature Conservancy, Iowa State University, the U.S. Fish and Wildlife Service, the Iowa Natural Heritage Foundation, and the Iowa Chapter of the Sierra Club, MidAmerican created a statewide map of areas in the proposed region that contained specific bird populations or habitats. Those areas were then avoided as site planning got underway in earnest. In order to minimize the wind farm's environmental impact even further, MidAmerican also worked in conjunction with the Army Corp of Engineers, to secure all necessary permits related to any potential risk to wetlands in the area. Regular inspections are also conducted to make certain that the wind farm is causing no adverse environmental impact to the region."

Other examples

• January 29, 1997: Baywind Energy Co-operative began operating a 2.5 megawatt five-turbine wind farm near Ulverston, Cumbria. It was the first co-operative to own wind turbines in the United Kingdom. It has raised two million pounds and has 1,300 members. A proportion of the profits are invested in local community environmental initiatives through the Baywind Energy Conservation Trust.
• June 29, 2003: After the Cape Wind project was proposed several miles off the coast of Cape Cod, some people raised objections, including U.S. Senator Ted Kennedy who owns a summer home in the area. But attitudes to the proposed wind farm have become more positive in recent years. A 2007 public opinion survey found that more than four out of five Massachusetts residents (84 percent) -- including 58 percent of those who live on the Cape -- explicitly supported the proposed Cape Wind offshore wind farm.
• On October 16, 2003 in Galway, Ireland, construction of the foundation of a wind farm caused almost half a square kilometer of bog to slide 2.5 kilometers down a hillside. The slide destroyed an unoccupied farmhouse and blocked two roads. Nearby residents expressed concern over these environmental impacts.
• On January 12, 2004, it was reported that the Center for Biological Diversity filed a lawsuit against wind farm owners for killing tens of thousands of birds at the Altamont Pass Wind Resource Area near San Francisco, California. In February 2008, a state appeals court upheld an earlier ruling that rejected the lawsuit.
• January 21, 2005: Three wind turbines on the island of Gigha in Scotland generate up to 675 kW of power. Revenue is produced by selling the electricity to the grid via an intermediary called Green Energy UK. Gigha residents control the whole project and profits are reinvested in the community. Local residents call the turbines "The Three Dancing Ladies".
• On December 4, 2007, environmentalists filed lawsuits to block two proposed wind farms in southern Texas. The lawsuits expressed concerns over wetlands, habitat, endangered species and migratory birds. In August 2008, a federal court judge dismissed the lawsuit, clearing the way for the completion of the wind farms by the end of 2008.
• On December 7, 2007, it was reported that some environmentalists opposed a plan to build a wind farm in western Maryland But other local environmentalists say that the environmental effects of wind farms "pale in comparison to coal-burning generators, which add to global warming and lead to acid rain" that is killing trees in the same area.
• On February 4, 2008, according to British Ministry of Defence turbines create a hole in radar coverage so that aircraft flying overhead are not detectable. In written evidence, Squadron Leader Chris Breedon said: "This obscuration occurs regardless of the height of the aircraft, of the radar and of the turbine."
• A February 21, 2008 article in Scoop reported on environmentalist opposition to a proposed wind farm in New Zealand.
• An April 16, 2008 article in the Pittsburgh Post-Gazette said that three different environmental organizations had raised objections to a proposed wind farm at Shaffer Mountain in northeastern Somerset County, Pennsylvania, because the wind farm would be a threat to the Indiana bat, which is listed as an endangered species.
• July 25, 2008: The Australian Hepburn Wind Project is a proposed wind farm, which will be the first Australian community-owned wind farm. The initiative emerged because the community felt that the state and federal governments were not doing enough to address climate change.
• August 12, 2008: The Ardrossan Wind Farm in Scotland has been "overwhelmingly accepted by local people". Instead of spoiling the landscape, they believe it has enhanced the area: "The turbines are impressive looking, bring a calming effect to the town and, contrary to the belief that they would be noisy, we have found them to be silent workhorses".
• A March 8, 2009 article in the Hawaii Free Press reported on an environmentalist organization called Maui Tomorrow that was against a proposed off-shore wind farm between O'ahu and Moloka'i.
• March 22, 2009: Some rural communities in Alberta, Canada want wind power companies to be allowed to develop wind farms on leased Crown land.

See also

• Environmental movement
• Environmental concerns with electricity generation