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A wind farm is a collection of wind turbines in the same location and used for the generation of wind power electricity.

Wind farms can be positioned on land or offshore. In Europe, offshore farms are more common, while they are just starting to be implemented in the United States.

Wind farms in the United States

The U.S. has several of the largest wind farms in the world. Three of the largest, Altamont Pass, San Gorgonio Pass and Tehachapi Pass, are located in California. The largest U.S. wind farm is the Stateline Wind Project on the Oregon-Washington line, with a peak capacity of 300 megawatts of electricity (although the three California wind farms mentioned are larger, they are actually collections of dozens of individual wind farms). The California wind farms have many different owners and turbine types and have been constructed, retrofitted and occasionally dismantled since they were first installed in late 1982. As of 2005 all three of these areas are seeing renewed growth. Primarily, the old, small wind turbines are being replaced with much larger, more efficient wind turbines. Some of the workhorses of the past were only 65 kilowatts (kW)in capacity size or even smaller, though some were several hundred kW. Today, the smallest utility-scale wind turbines are about 700 kW, with a few models approaching 5,000 kW (5 MW). Secondarily, non-functional turbines are also being returned to service.

The Altamont Pass in Northern California is one of the earliest large wind farms. It is composed of large numbers of relatively small wind turbines of various types that were installed after the 1970s energy crisis in response to favorable tax policies for investors. However, the types of incentives the government uses have led to an unhealthy cycle of booms and busts for the wind energy industry. The problems were not so much with the wind turbines themselves. Only a few of the turbine designs were fatally flawed and almost all of the others were able to be rehabilitated into excellent machines. Still, these numerous small turbines are being gradually replaced with much larger and more cost-effective units. An advantage of the Altamont Pass site is that under hot inland (Central Valley) conditions, a thermal low is developed that brings in cool coastal marine air, driving the turbines at a time of maximum electricity demand. However, this phenomenon is not always reliable and with an inland high pressure condition the entire region can be both hot and windless. At this time additional power must be provided by natural gas-powered gas turbine peaker plants. The turbines are dangerous to various raptors that hunt ground squirrels in the area and sometimes collide with the machines.

The Tehachapi Pass and San Gorgonio Pass sites have not had the same problems as Altamont Pass has had. The winds at these sites are more consistent. Also, endangered bird kills have not been an issue.

Even though California has the largest wind farms in the U.S., it does not have very many commercially viable wind farm sites, at least not onshore. Much of the Southwest is not much better, although there are some significant exceptions. However, the Midwest has an abundance of suitable sites for wind energy development and yet the region's potential has gone largely untapped. As of 2005, several sites have been constructed or are in development in the Midwest. The Pacific Northwest and the Northeast both have many excellent sites as well. In contrast, the Southeast has a very poor wind energy resource, though the Appalachian Mountains do provide a few good areas.

In Massachusetts, two proposed wind farms have had approval difficulties. The Cape Wind project, a proposal to construct 130 offshore wind turbines in the Nantucket Sound, is the subject of heavy debate in the affluent communities of Cape Cod, Martha's Vineyard, and Nantucket as well as among environmentalists. The Hoosac Wind project, which will build 20 turbines on two ridgelines in the rural towns of Florida and Monroe, was initially the subject of little official controversy, but has been delayed by a suit to protect wetlands. Several other projects have been proposed for the area.

Another 40-turbine offshore wind power installation has been proposed for the ocean off Jones Beach, Long Island, New York. It has the backing of many local and national environmental groups * as well as the Long Island Power Authority and the Governor of New York.

In New Jersey, the country's first coastal wind farm became operational in December 2005. The Jersey-Atlantic Wind Farm in Atlantic City consists of five 1.5-MW turbines.

The American Wind Energy Association provides information about existing and proposed projects in the U.S.

As of May 31, 2006, the FAA has stopped construction at 15 midwest wind farm projects over concerns about interference with military radar.*

Wind farms in Europe

The development of wind farms in Europe enjoys greater public acceptance and creates a larger share of energy. Germany has the biggest wind turbine to be established offshore, and the largest number of wind farms in the world.

Governmental policy is generally in favour of increasing the use of renewable energy sources. The United Kingdom government, for example, has a target for 10% of domestic energy consumption to be generated from renewable sources by the year 2010. A number of on- and off-shore wind farms are currently going through planning permission at the moment. Recently an onshore farm was opened at Cefn Croes in West Wales's Cambrian Mountains *. In May 2006, operational wind farms in the UK comprised an installed capacity of 1693 MW, in France 918 MW and in the Republic of Ireland 496 MW.

Wind farms in different countries yield different amounts of electricity, because of differences in prevailing wind patterns, siting of the turbines, and the fact that early turbine designs were considerably less efficient and capable of adapting quickly to changes in wind direction and speed. For example, an Oxford University study of the wind over the past 35 years found that UK turbines would have produced 27% of their maximum possible energy, compared with 20% in Denmark and 15% in Germany. *

Wind farms in Japan

There is no particular controversy about the sightliness or otherwise of the Wakamatsu ward windfarm in Kitakyushu, as there is in some other countries. It is far from the scenic areas of Wakamatsu, and on windy reclaimed land. Asahi Shimbun reported on May 18, 2005 that many utilities have put limits on the amount of wind power they will allow, because of lack of confidence in their ability to deal with the variable output. It should be noted that several European countries are successfully accommodating significantly higher shares of wind energy in to their networks and that the Japanese grid is capable of coping with large conventional power stations disconnecting unexpectedly due to faults; on the other hand, it is true that integrating windpower or unreliable conventional power stations in to island grids is more difficult than into continent-wide inter-connected grids.

Wind farms in Canada

The total capacity of all wind farms in Canada is approximately 1,049 MW as of July 2006 *. Each province contains the following capacity:
  1. Alberta, 284.47 MW,
  2. Ontario, 220.71 MW,
  3. Quebec, 212 MW,
  4. Saskatchewan, 171.1 MW,
  5. Manitoba, 103.95 MW,
  6. Nova Scotia, 41.26 MW,
  7. Prince Edward Island, 13.56 MW,
  8. Yukon, 0.810 MW, and
  9. Newfoundland, 0.39 MW.

The five largest wind farms in Canada are:

  1. Centennial (SaskPower near Swift Current, Saskatchewan), 149.4 MW
  2. Erie Shores (Ontario), 99 MW
  3. McBride Lake (near Fort Macleod, Alberta), 75 MW
  4. Summerview (near Pincher Creek, Alberta), 68 MW
  5. Melanchton 1 - Shelburne (Ontario), 67.5 MW

Government support for wind power continues to increase. The current Wind Power Production Incentive (WPPI)* is expected to quadruple its goal of 1,000 MW of wind power to 4,000 MW. There is an additional 2,811 MW planned or under construction.

Controversy

The following subsections outline some of the current controversies concerning wind power.

Cost and Reliability

One of the major questions raised about the use of wind power is its ability to serve as a large-scale energy source. Reliability of wind power is viewed by some as a major obstacle to increased integration, while others argue that its cost is too high. A recent report by the Utility Wind Interest Group (UWIG) stated that "On the cost side, at wind penetrations of up to 20% of system peak demand, system operating cost increases arising from wind variability and uncertainty amounted to about 10% or less of the wholesale value of the wind energy." The report added that some of this cost increase can be reduced by using wind forecasting and other means. The report also stated that "The addition of a wind plant to a power system increases the amount of variability and uncertainty of the net load. This may introduce measurable changes in the amount of operating reserves required for regulation, ramping and load-following. In two major recent studies, the addition of 1,500 MW and 3,300 MW of wind (15% and 10%, respectively, of system peak load) increased regulation requirements by 8 MW and 36 MW, respectively, to maintain the same level of NERC control performance standards. *ariability and uncertainty introduced by wind plants have been shown to increase system operating costs by up to about $5/MWH at wind penetration levels up to 20%." With regard to reliability, the report states, "Further, there is evidence that with new equipment designs and proper plant engineering, system stability in response to a major plant or line outage can actually be improved by the addition of wind generation."

Effects on the Community

Wind farms have been opposed by those who feel that the siting of some of them spoil the landscape, particualry in countryside areas of outstanding natural beauty where there is otherwise no industrialisation nor development (e.g. Snowdonia, Cumbria). Others say they feel that the wind turbines are beautiful regardless where they are sited.

A study by the University of St Andrews of 2 Scottish and one Irish site found that support for wind farms was higher among those living near existing sites, than among those living near proposed sites. The study also found that, in the case of the Dun Law Wind Farm in the Scottish Borders, that support for the farm was lowest among residents living 10-20 km away, with support being higher closer to the farm. However, none of these sites involved areas of outstanding natural beauty.

Other criticisms include noise and vibration produced by the blades, gears, and motors, the flashing lights required on the tall towers (for aviation safety), the shadows cast by the rotating blades, and many more. At the same time, there are many neighbors of wind facilities who report no problems with them (see, for example, testimonials collected by the Alliance for Clean Energy New York, an advocacy group).

Environmental Concerns

Some question whether windmills are a significant danger to passing birds. One large wind farm in California's Altamont Pass has been shown to kill 300 red-tailed hawks and 60 golden eagles a year. However, the pass is an area with very high year-round raptor use, and the raptor mortality rate there is far higher than at other wind farms. In the UK, the Royal Society for the Protection of Birds (RSPB) has studied this matter and concluded that "The available evidence suggests that appropriately positioned wind farms do not pose a significant hazard for birds" (see RSPB statement on wind farms). It notes that climate change poses a much more significant threat to wildlife, and therefore supports wind farms and other forms of renewable energy.

A study of a Danish offshore wind farm used radar to track flocks of geese and eider ducks around the Nysted wind farm in the Baltic sea. It found that the birds flew almost exclusively down the corridors between the 72 turbines, with less than one per cent flying close enough to risk collision. Many also avoided the wind farm altogether. The study was by Mark Desholm and Johnny Kahlert of the National Environmental Research Institute in Rønde, Denmark (New Scientist, vol 186, no 2504: 18 June 2005). The study did not, however, use data during twilight hours or anything more than mild winds, and the researchers warn about the possible cumulative effect of increasing numbers of wind facilities.

A Norwegian wind farm built on the Smøla islands has raised environmental concerns as nine sea eagles have died after colliding with turbine rotor blades. These deaths all occurred after the opening in September 2005 of Phase 2 of the wind farm These deaths included all of the previous year's chicks, and the number of breeding pairs on the islands reduced from 19 to one in the same period [http://news.bbc.co.uk/1/hi/world/europe/5108666.stm.

Problems of Wind Farm Implementation

By themselves, wind farms are not suitable for replacement of base-load electricity supply, such as that supplied by coal-fired or nuclear power stations. This is because wind power output is variable and unpredictable with sufficient accuracy. As a result, continuity of electricity supply needs to be assured both by having loads that can be switched off at times of high demand, and by having power generation facilities that can be ramped up in approximately the same timescale that wind power diminishes. Such power generation types are generally more expensive per unit of electicity generated than base-load generators, so electricity suppliers prefer to minimise their use. Still, electricity demand on a power system varies throughout the day, and the additional variability introduced by wind generation is modest. The Utility Wind Integration Group, reviewing the state of the art in utility integration of wind, comments: "Given the existing uncertainties in load forecasts . . . studies indicate that the requirement for additional reserves will likely be modest for broadly distributed wind plants."

Wind power also suffers as it generates electricity that is decoupled from demand - the wind does not stop blowing when industrial activity stops for the night, for example. Storage methods for power generated in excess of demand are limited by the technology available in the first decade of the 21st century. Some schemes that reverse hydroelectric operation by pumping water to replenish hydroelectric reservoirs are in operation, but such schemes are inefficient (70-85% efficiency - see Pumped-storage hydroelectricity), and depend on favourable geography.

The above problems are mitigated in part by increasing the scale of implementation. With more wind farms spread over a wider area, it is less likely that all the wind farms will simultaneously experience low-wind conditions. The area required is large, however, as low-wind high-pressure regions can form that cover most of Western Europe and or the British Isles for long periods in Northern Hemisphere summers. In addition, although pumped storage is inefficient, once the capital investment is made in the wind farm infrastructure, the marginal cost of generating the power to pump water is small. Pumped storage also provides a reservoir of power that can be ramped up quickly to even out short term wind power fluctuations.

Integrating wind power with existing systems can also be tricky. A recent article by the UWIG stated that "Upgrades or additions to transmission facilities may be needed to access locations with large wind-energy potential. Current transmission planning processes are able to identify solutions to transmission problems, but the time required for implementation of solutions often exceeds wind-plant permitting and construction times by several years."

See also


External links

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This article is licensed under the GNU Free Documentation License. It uses material from the "Wind farm".

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