Frequently Asked Questions

Wind power supplies affordable, inexhaustible energy to the economy. It also provides jobs and other sources of income. Best of all, wind powers the economy without causing pollution, generating hazardous wastes, or depleting natural resources - it has no "hidden costs." Finally, wind energy depends on free fuel source - the wind - and so it is relatively immune to inflation.

Coal, the most polluting fuel and the largest source of the leading greenhouse gas, carbon dioxide (CO2), is currently used to generate more than half of all of the electricity (52%) used in the United States. Other sources of electricity are: natural gas (16%), oil (3%), nuclear (20%), and hydropower (7%).

The U.S. wind industry currently directly employs more than 2,000 people. The wind industry contributes directly to the economies of 46 states, with power plants and manufacturing facilities that produce wind turbines, blades, electronic components, gearboxes, generators, and a wide range of other equipment.

The Renewable Energy Policy Project (REPP) estimates that every megawatt of installed wind capacity creates about 4.8 job-years of employment, both direct (manufacturing, construction, operations) and indirect (advertising, office support, etc.). This means that a 50 MW wind farm creates 240 job-years of employment. According to a REPP study released in October 2004, boosting U.S. wind energy installations to approximately eight times today's levels could create 150,000 manufacturing jobs nationwide, with most jobs being added in the 20 states that have lost the most in recent years.

According to REPP, some 90 companies in 25 states currently manufacture wind turbine components, and over 16,000 companies in all 50 states have the technical potential to enter the wind turbine market. The full report is available on the REPP Website at:

Wind and solar energy are likely to be among the largest sources of new manufacturing jobs worldwide during the 21st Century.

Exports markets are growing rapidly. Overseas markets account for about half of the business of U.S. manufacturers of small wind turbines and wind energy developers. Small wind turbine markets are diverse and include many applications, both on-grid (connected to a utility system) and off-grid (stand-alone).

The potential economic benefits from wind are enormous. At a time when U.S. manufacturing employment is generally on the decline, the production of wind equipment is one of the few potentially large sources of new manufacturing jobs on the horizon.

AWEA estimates that wind installations worldwide will total more than 100,000 megawatts over the next decade, or more than $100 billion worth of business. If the U.S. wind industry could capture a 25% share of the global wind market through the year 2015, many thousands of new jobs would be created.

Wind farms can revitalize the economy of rural communities providing steady income through lease or royalty payments to farmers and other landowners. Although leasing arrangements vary widely, a reasonable estimate for income to a landowner from a single utility-scale turbine is about $3,000 a year. For a 250-acre farm, with income from wind at about $55 an acre, the annual income from a wind lease could be $14,000, with no more than 2-3 acres removed from production. Such a sum can significantly increase the net income from farming. Farmers can grow crops or raise cattle next to the towers. Wind farms may extend over a large geographical area, ut their actual "footprint" covers only a very small portion of the land, making wind development an ideal way for farmers to earn additional income. In West Texas, for example, farmers are welcoming wind, as lease payments from this new clean energy source replace declining payments from oil wells that have been depleted.

Farmers are not the only ones in rural communities to find that wind power can bring in income. In Spirit Lake, Iowa, the local school is earning savings and income from the electricity generated by a turbine. In the district of Forest City, Iowa, a turbine recently erected as a school project is expected to save $1.6 million in electricity costs over its lifetime.

Additional income is generated from one-time payments to construction contractors and suppliers during installation, and from payments to turbine maintenance personnel on a long-term basis. Wind farms also expand the local tax base, and keep energy dollars in the local community instead of spending them to pay for coal or gas produced elsewhere.

Finally, wind also benefits the economy by reducing "hidden costs" resulting from air pollution and health care. Several studies have estimated that 50,000 Americans die prematurely each year because of air pollution.

I've heard that rising natural gas prices are hurting our economy. Is this a problem that wind energy can help to solve?

Yes. When a wind farm generates electricity in the U.S. the fuel that is most likely to displace is natural gas. In mid-2003, when Federal Reserve Board Chairman Alan Greenspan testified before Congress that rising natural gas prices were threatening the economy's future, the American Wind Energy Association (AWEA) estimated that U.S. wind plants were already reducing the national natural gas shortage by 10-15%. AWEA stated that enough wind plants could be built within four years to eliminate the entire gas shortage (estimated at 3-4 billion cubic feet of gas per day).

Where wind energy is concerned, utility restructuring has both positive and negative impacts.

On the positive side, as with long-distance telephone service, restructuring offers consumers a chance to choose to buy their electricity from a number of different service providers. Since electricity generation, unlike phone service, has major environmental impacts, it seems likely that some of these service providers will choose to offer "green" (environmentally-friendly) products from clean power sources like wind. Indeed, many electric utilities are already offering wind-generated electricity as an option today.

On the negative side, the primary purpose of restructuring is to allow large industrial companies to shop among power suppliers for the cheapest price. It does this regardless of the environmental impacts of the sources that are used. This has led to increasing generation from older, dirtier coal-fired plants that were "grandfathered" (exempted from having to install new pollution controls) under the Clean Air Act. To the degree that restructuring encourages cheap generation regardless of environmental costs, it is harmful to wind energy.

One solution that has been suggested to some of the problems posed by restructuring is the Renewable Portfolio Standard (RPS).

The Renewables Portfolio Standard (RPS) would require each company that generates electricity in the U.S., or in a given state, to obtain part of the electricity it supplies from renewable energy sources such as wind. To meet this requirement, the company could either generate electricity from renewables itself or buy credits or electricity from a renewable generator such as a wind farm. This "credit trading" system has been used effectively by the Federal Clean Air Act to require utilities to reduce pollutant emissions.

Aside from the "minimum renewable content" requirement, the RPS imposes very few other requirements on companies - they are free to buy, trade, or generate electricity from renewables in whatever fashion is most efficient and economical for them. The RPS is therefore often described by its supporters as being "market-friendly," because it allows market forces to decide which renewable energy sources will be developed where, and also allows price competition.

Several federal restructuring bills have included an RPS, and at least 20 states have also adopted RPS laws. One federal proposal, for example, would require 20% of U.S. electricity to come from non-hydro renewable energy sources (wind, solar, biomass, geothermal) by the year 2020. Typically, the RPS gradually increases over time, by 1% per year or some such number, in order to provide a foundation for the sustained, orderly development of renewable energy industries.

Yes. The United States is blessed by an abundance of renewable energy resources from the sun, wind and earth. Good wind areas, covering only 6% of the land area of the "lower 48" states, could theoretically supply more than one and a third times the total current national demand for electricity. A 12,000-square-mile area in Nevada could produce enough electricity from the sun to meet annual national demand. There are large untapped geothermal and biomass (energy crops and plant waste) resources. Of course, there are limits to how much of this potential can be used economically, because of competing land issues, competing costs from other energy sources, and limits to the transmission system. The important question is how much would it cost to supply 20% of our electricity from renewable energy sources other than hydroelectric power.

Not very much. A major study in 2002 by the U.S. Energy Information Administration (EIA) - using very high estimates of renewable energy costs - found that an RPS of 20% would raise electricity costs by about 0.2 cents per kilowatt-hour (kWh), from 6.6 cents/kWh to 6.8 cents/kWh. Further, most of the increase would be offset by reductions in the price of natural gas for home heating. Other studies, using more realistic assumptions developed by the U.S. Department of Energy's Interlaboratory Working Group, consisting of the five national energy research labs, have found that a 20% RPS, when combined with energy efficiency programs, could save consumers billions of dollars.

Green power is a term applied to electricity that is generated from wind and other renewable energy sources, such as solar, geothermal, biomass, and small hydropower. Typically, the environmental impacts of these sources are quite modest compared to those of coal and other conventional sources.

Green power programs vary, but one common approach, called "green pricing," is for a utility to offer its customers the option of buying electricity generated from wind at a premium price. For example, a customer might be able to sign up to receive a certain number of 100-kilowatt-hour "blocks" of electricity from wind each month for an extra $2 each (that is, 2 cents per kilowatt-hour). A customer signing up for 2 blocks at $2 would pay $4 more for electricity each month and "receive" 200 kilowatt-hours of wind-generated electricity. The utility would then add enough wind capacity to its generating mix to provide the additional electricity required. (The utility cannot deliver specific electrons from any of its plants to a specific customer. Instead, its generating mix should be thought of as a pool. Power plants add electricity to the pool and customers take it out. With green power, the utility adds more wind energy to the pool based on the amount customers have said they desire to purchase.)

A second form of green power is used in states that have opened their electricity markets to competition (in much the same way as long-distance telephone service is now open to competition). In these states, electricity suppliers offer electricity "products" from renewable and other sources, and customers are free to sign up for the product and company they prefer. One company, for example, might offer a product that is called "Earth Saver" that is 50% wind-generated electricity and 50% electricity from landfill gas, and charge 1.5 cents/kWh more than "system power" (regular commodity electricity from the regional generating mix).

A third form of green power is called "green tags" and can be used by consumers anywhere to "green" their electricity supply. With this approach, when a certain amount of electricity (for example, 1,000 kWh) is generated from a renewable source, a certificate called a "green tag" is created. The generator sells the electricity into the commodity wholesale market, but keeps the certificate (which represents the beneficial environmental attributes of the electricity) and sells it to an interested buyer for an agreed-upon price (for example, $20, or 2 cents/kWh). By buying green tags that represent the amount of renewable generation equal to your electricity use, you can, in effect, "green" your power supply in much the same way that you would through "green pricing" or "green power" - you are paying extra, and extra renewable energy is being delivered to the utility system based upon your payment.

No one knows yet how successful green programs and products will be in the electricity marketplace. If consumers learn more about the air pollution, strip mining, and other harmful environmental impacts of electricity generation and decide to "vote with their dollars" for clean energy, green power could become a large and growing business over the next decade and beyond.

Some of the most common reasons why people buy green power are to:

  1. Improve human health
  2. Preserve the earth for their children and grandchildren
  3. Reduce environmental impacts
  4. Conserve finite fossil resources

Green power can also offer protection against rising electricity prices or price volatility. We have seen the devastating effects of volatile wholesale electricity prices in California in 2000 and early 2001. In addition, natural gas prices, which influence electricity prices, have "spiked" three times in the last five years, rising sharply above historic ranges.

Probably not - the flow of electricity usually follows the path of least resistance to the nearest demand, so you probably don't get "green" electrons flowing directly from a wind farm to your home. The electricity system operates like a large pool of water, with many pumps (power plants) adding water and many outlets (customers) withdrawing it. When you buy green power, instead of actually getting it at your home or business, you are helping to change the mix of generating plants that put electricity into the "pool." Each green power provider either generates, or purchases from a generator, enough wind or other renewable energy to supply the amount of electricity that green power customers are purchasing. By selecting wind energy over conventional electricity generation, consumers indicate support for the growth of America's wind energy industry and encourage utilities to add and expand green power programs. As the popularity of green power grows, power producers have to build additional wind plants to meet growing demand.

Yes. Remember that wind energy is not delivered directly to your home. Instead, the wind energy goes into a "pool" along with other types of energy generation. It is this "pool" that serves all electricity users. This is true whether or not the wind blows. Therefore, if one plant, say a wind turbine (but also any other power plant), isn't generating, then another plant will be asked to generate more electricity to meet demand. (The green power provider does not have to guarantee a steady supply of green electricity, but rather only to generate or buy as much green electricity over the course of a year or month as you pay for).

Most power outages or interruptions in your service are not caused by whether or not a particular generator is operating. Instead, the problem is usually in the distribution system - for example, power lines downed from a storm. So you'll still call your local distribution utility when you have a problem.

Governments federal, state, and local are jointly the largest consumer of energy and electricity in the United States.

In 1998, the federal government alone consumed 1,077 trillion British thermal units (Btu) of energy, or 1.14% of the nation's total energy use. Within that total, it consumed approximately 54 billion kilowatt-hours of electricity, or about 1.6% of total national electricity use. The federal government's total energy bill was $8 billion, or 2% of the federal consumption of goods and services. Its electricity bill was approximately $3.5 billion. Perhaps more important, in 1998 the federal government used more than twice as much electricity as was generated by all the solar, wind, and geothermal facilities owned by utilities and the industrial sector nationwide. Federal energy dollars could have a great impact on renewable energy markets.

By and large, the potential of government purchases to encourage clean energy industries has not been realized. In early 1999, President Clinton issued an Executive Order that urges government agencies to consider the federal government's policy of supporting renewable energy in making energy purchases. More recently, the federal Environmental Protection Agency (EPA) has announced that one of its facilities in California will be entirely supplied by green power, and the U.S. Army has announced plans to develop wind energy at Fort Bliss, New Mexico. More commonly, though, government agencies, like industrial companies and many individual consumers, look for the cheapest electricity source, regardless of environmental consequences.

Wind energy currently receives a direct subsidy, the Production Tax Credit (PTC). The PTC provides a tax credit of 1.5 cents per kilowatt-hour (adjusted for inflation, currently 1.9 cents) to the producer of electricity from wind energy. The PTC was an acknowledgement that wind energy can play an important role in the nation's energy mix. It was also a recognition that the federal energy tax code favors established, conventional energy technologies. The PTC currently is scheduled to expire December 31, 2007.

All energy technologies are subsidized by the U.S. taxpayer. Subsidies come in various forms, including payment for production, tx deductions, guarantees, and leasing of public lands at below-market prices. Subsidies can also be provided indirectly, for example through federal research and development programs, and provisions in federal legislation and regulations. For example, loopholes in the Clean Air Act currently exempt older power plants from compliance with federal pollution standards and become, in effect, a subsidy that lowers the price of electricity from coal-fired power plants.

Here are some conclusions from a detailed 1993 study of energy subsidies by the Alliance to Save Energy (Federal Energy Subsidies: Energy, Environmental, and Fiscal Impacts):

"Energy subsidies in 1989 favored mature, conventional energy supply resources by $32.3 billion over non-conventional energy resources." ($21 billion went to fossil fuels, $11 billion to nuclear, and $900 million to all renewable energy sources including wind.) "There is currently no free market in energy. Given the size of federal energy subsidies, now and in the past, it is erroneous to speak of a 'free market' in energy... It may be appropriate to subsidize emerging energy resources, but mature resources should stand the test of the market. When this test is applied to subsidies in 1989, the pattern appears to be almost completely backward. In other words, the mature, conventional technologies received almost 90% of the subsidies."

The pattern of subsidies that the Alliance found is also flatly opposed to the views of the American public. In numerous public opinion surveys over the past several years, those surveyed have favored providing government assistance to clean energy sources and not to nuclear or fossil fuels. For example, in one national poll conducted in mid-1999, 80% of the respondents said they favor the use of tax incentives to increase the use of renewable energy for the production of electricity.

Net metering or net billing is a term applied to laws and programs under which a utility allows the meter of a customer with a residential power system (such as a small wind turbine) to turn backward, thereby in effect allowing the customer to deliver and excess electricity he produces to the utility and be credited on a one-for-one basis against the electricity the utility supplies to him.

Example: During a one-month period, John Doe's wind turbine generates 300 kilowatt-hours (kWh) of electricity. Most of the electricity generated is generated at a time when equipment in John's household (refrigerator, lights, etc.) is drawing electricity and is used on site. However, some is generated at night when most equipment is turned off. At the end of the month, the turbine has generated 100 kWh in excess of John's instantaneous needs and that electricity has been transmitted to the utility system. During the month, the utility also supplied John with a total of 500 kWh for his use at times when the wind turbine was not generating or was insufficient for his needs. Since the meter ran backward while 100 kWh was being transmitted to the utility, the utility will only bill John for 400 kWh, rather than 500 kWh.

Net metering can improve the economics of a residential wind turbine by allowing the turbine's owner to use her excess electricity to offset utility-supplied power at the full retail rate, rather than having to sell the power to the utility at the price the utility pays for the wholesale electricity it buys or generates itself. Many utilities have argued against net metering laws, saying that they are being required, in effect, to buy power from wind turbine owners at full retail rates, and are therefore being deprived of a profit on part of their electricity sales. However, wind energy advocates have successfully argued that what is going on is a power swap, and that it is a standard practice in the utility industry for utilities to trade power among themselves without accounting for differences in the cost of generating the various kilowatt-hours involved.

Today, net metering's popularity is growing. Thirty-four states have enacted it in some form, and others are considering it.

Utilities must maintain enough power plant capacity to meet expected customer electricity demand at all times, plus an additional reserve margin. All other things being equal, utilities generally prefer plants that can generate as needed (that is, conventional plants) to plants that cannot (such as wind plants).

However, despite the fact that the wind is variable and sometimes does not blow at all, wind plants do increase the overall statistical probability that a utility system will be able to met demand requirements. A rough rule of thumb is that the capacity value of adding a wind plant to a utility system is about the same as the wind plant's capacity factor multiplied by its capacity. Thus, a 100-megawatt wind plant with a capacity factor of 35% would be similar in capacity value to a 35-MW conventional generator. For example, in 2001 the Colorado Public Utility Commission found the capacity value of a proposed 162-MW wind plant in eastern Colorado (with a 30% capacity factor) to be approximately 48 MW.

The exact amount of capacity value that a given wind project provides depends on a number of factors, including average wind speeds at the site and the match between wind patterns and utility load (demand) requirements. It also depends on how dispersed geographically wind plants on a utility system are, and how well-connected the utility is with neighboring systems that may also have wind generators. The broader the wind plants are scattered geographically, the greater the chance that some of them will be producing power at any given time.

As of the end of 2004, there were over 47,000 megawatts of generating capacity operating worldwide, producing some 100 billion kilowatt-hours each year - as much as 9 million average American households use, or as much as a dozen large nuclear power plants could generate. Yet this is but a tiny fraction of wind's potential.

According to the U.S. Department of Energy, the world's winds could theoretically supply the equivalent of 5,800 quadrillion BTUs (quads) of energy each year - more than 15 times current world energy demand. (A quad is equal to about 172 million barrels of oil or 45 million tons of coal).

The potential of wind to improve the quality of life in the world's developing countries, where more than two billion people live with no electricity or prospect of utility service in the foreseeable future, is vast.

The "energy payback time" is a tem used to measure the net energy value of a wind turbine or other power plant - i.e., how long does the plant have to operate to generate the amount of electricity that was required for its manufacture and construction? Several studies have looked at this question over the years and have concluded that wind energy has one of the shortest energy payback times of any energy technology. A wind turbine typically takes only a few months (3-8, depending on the average wind speed at its site) to "pay back" the energy needed for its fabrication, installation, operation, and retirement.

At current levels of use, this issue is till some distance from being a problem on most utility systems. The rule of thumb (admittedly rough) is:

Up to the point where wind generates about 10% of the electricity that the system is delivering in a given hour of the day, it's not an issue. There is enough flexibility built into the system for reserve backup, varying loads, etc., that there is effectively little difference between such a system and a system with 0% wind. Variations introduced by wind are much smaller than routine variations in load (customer demand).

At the point where wind is generating 10% to 20% of the electricity that the system is delivering in a given hour, it is an issue that needs to be addressed, but that can probably be resolved with wind forecasting (which is fairly accurate in the time frame of interest to utility system operators), system software adjustments, and other changes.

Once wind is generating more than about 20% of the electricity that the system is delivering in a given hour, the system operator begins to incur significant additional expense because of the need to procure additional equipment that is solely related to the system's increased variability.

These figures assume that the utility system has an "average" amount of resources that are complimentary to wind's variability (e.g., hydroelectric dams) and an "average" amount of load that can vary quickly (e.g., electric arc furnace steel mills). Actual utility systems can vary quite widely in their ability to handle as-available output resources like wind farms. However, as wholesale electricity markets grow, fewer, larger utility systems ar emerging. Therefore, over time, more and more utility systems will look like an "average" system.

Wind energy system operations do not generate air or water emissions and do not produce hazardous wastes. Nor do they deplete natural resources such as coal, oil, or gas, or cause environmental damage through resource extraction and transportation, or require significant amounts of water during operation. Wind's pollution-free electricity can help reduce the environmental damage caused by power generation in the U.S. and worldwide.

In 1997, U.S. power plants emitted 70% of sulfur dioxide, 34% of carbon dioxide, 33% of nitrogen oxides, 28% of particulate matter and 23% of toxic heavy metals released into our nation's environment, mostly the air. These figures are currently increasing in spite of efforts to roll back air pollution through the Federal Clean Air Act.

Sulfur dioxide and nitrogen oxides cause acid rain. Acid rain harms forests and the wildlife they support. Many lakes in the U.S. Northeast have become biologically dead because of this form of pollution. Acid rain also corrodes buildings and economic infrastructure such as bridges. Nitrogen oxides (which are released by otherwise clean-burning natural gas) are also a primary component of smog.

Carbon dioxide (CO2) is a global warming pollutant - its buildup in the atmosphere contributes to global warming by trapping the sun's rays on the earth as in a greenhouse. The U.S., with 5% of the world's population, emits 23% of the world's CO2. The build-up of global warming pollution is not only causing a gradual rise in average temperatures, but also seems to be increasing fluctuations in weather patterns and causing more frequent and severe droughts and floods. The World Meteorological Organization (WMO) warned in July, 2003, that extreme weather events appear to be increasing in number due to climate change.

Particulate matter is of growing concern because of its impacts on health. Its presence in the air along with other pollutants has contributed to make asthma one of the fast growing childhood ailments in industrial and developing countries alike, and it has also recently been linked to lung cancer. SImilarly, urban smog has now been linked to low birth weight, premature births, stillbirths and infant deaths. In the United States, the research has documented ill effects on infants even in cities with modern pollution controls.

Toxic heavy metals accumulate in the environment and up the biological food chain. A number of states have banned or limited the eating of fish from fresh-water lakes because of concerns about mercury, a toxic heavy metal, accumulating in their tissue.

Development of just 10% of the wind potential in the 10 windiest U.S. states would provide more than enough energy to displace emissions from the nation's coal-fired power plants and eliminate the nation's major source of acid rain; reduce total U.S. emissions of CO2 by almost a third; and help contain the spread of asthma and other respiratory diseases aggravated or caused by air pollution in this country.

If wind energy were to provide 20% of the nation's electricity - a very realistic and achievable goal with the current technology - it could displace more than a third of the emissions from coal-fired power plants.

In 2006, the American Wind Energy Association estimates that wind plants in the U.S. will generate 24 billion kilowatt-hours. If instead the average utility fuel mix were used to generate that much electricity, 30 billion pounds (15 million tons) of carbon dioxide, 76,000 tons of sulfur dioxide (208 tons per day), and 36,000 tons of nitrogen oxides (100 tons per day) would be released into the atmosphere.

Yes! Carbon dioxide (CO2) is the most important of the global warming pollutants which are changing our climate. According to experts, if we are to avoid dangerous levels of warming, we must cut our CO2 emissions by 80-90% by 2050. That means switching to forms of energy generation that do not produce CO2.

Wind power is a clean, renewable form of energy, which during operation produces no carbon dioxide. While some emission of these gases will take place during the design, manufacture, transport and erection of wind turbines, enough electricity is generated from a wind farm within a few months to totally compensate for these emissions. When wind farms are dismantled (usually after 20-25 years of operation) they leave no legacy of pollution for future generations.

Given the scale of CO2 cuts needed, wind power - as the least expensive, most developed renewable energy technology and the fastest to build - is the best placed renewable technology to deliver carbon emissions reductions on a large scale, quickly.

Yes! In 2000, the Harvard School of Public Health looked at the human health effects from two fossil-fuel-fired power plants in Massachusetts. It estimates that the air pollution from the plant causes:

  1. 159 premature deaths
  2. 1,710 emergency room visits
  3. 43,300 asthma attacks

each year. Replacing as much of this electricity as possible with wind energy would clearly lower associated health care costs.

Wind power plants, like all other energy technologies, have some environmental impacts. However, unlike most conventional technologies (which have regional and even global impacts due to their emissions and fuel imports), the impacts of wind energy systems are minimal and local. This makes them easier for local communities to monitor and, if necessary, mitigate.

The local and environmental impacts that can result from wind power development include:

Erosion which can be prevented through proper installation and landscaping techniques. Erosion can be a concern in certain habitats such as the desert, where a hard-packed soil surface must be disturbed to install wind turbines. Erosion has also been raised as a concern in the easter U.S. where wind farms typically must be installed on mountain ridgelines. However, standard engineering practices used by ski areas on the same kind of terrain are adequate to deal with any erosion issues that might be raised by construction of a wind farm and its service road.

birds occasionally collide with wind turbines, as they do with other tall structures such as buildings. Avian deaths have become a concern at Altamont Pass in California, which is an area of extensive wind development and also high year-round raptor use. Detailed studies, and monitoring following construction, at other wind development areas indicate that this is a site-specific issue that will not be a problem at most potential wind sites. Also, wind's overall impact on birds is low compared with other human-related sources of avian mortality.

No matter how extensively wind is developed in the future, bird deaths from wind energy are unlikely to ever reach as high as 1% of those from other human-related sources such as hunters, house cats, buildings, and autos. (House cats, for example, are believed to kill 1 billion birds annually in the U.S. alone). Wind is, quite literally, a drop in the bucket. Still, areas that are commonly used by threatened or endangered bird species should be regarded as unsuitable for wind development. The wind industry is working with environmental groups, federal regulators, and other interested parties to develop methods of measuring and mitigating wind energy's effect on birds.

Wind energy can also negatively impact birds and other wildlife by fragmenting habitat, both through installation and operation of wind turbines themselves and through the roads and power lines that may be needed. This has been raised as an issue in areas with unbroken stretches of prairie grasslands or of forests. More research is needed to better understand these impacts.

Bat collisions at wind plants generally tend to be low in number and to involve common species with are quite numerous. Human disturbance of hibernating bats in caves is a far greater threat to species of concern. Still, a surprisingly high number of bat kills at a new wind plant in West Virginia in the fall of 2003 has raised concerns, and research at that plant and another in Pennsylvania in 2004 suggests that the problem may be a regional one. The wind industry has joined with the U.S. Fish and Wildlife Service, the U.S. Department of Energy's National Renewable Energy Laboratory, and Bat Conservation International to form the Bats and Wind Energy Cooperative (BWEC), which funded the 2004 research program and is continuing to explore ways to avoid or reduce bat kills.

Visual impacts can be minimized through careful design of a wind power plant. Using turbines of the same size and type and spacing them uniformly generally results in a wind plant that satisfies most aesthetic concerns. Computer simulation is helpful in evaluating visual impacts before construction begins. Public opinion polls show that the vast majority of people favor wind energy, and support for wind plants often increases after they are actually installed and operating.

Noise was an issue with some early wind turbine designs, but it has been largely eliminated as a problem through improved engineering and through appropriate use of setbacks from nearby residences. Aerodynamic noise has been reduced by changing the thickness of the blades' trailing edges and by making machines "upwind" rather than "downwind" so that the wind hits the rotor blades first, then the tower (on downwind designs where the wind hits the tower first, its "shadow" can cause a thumping noise each time a blade passes behind the tower). A small amount of noise is generated by the mechanical components of the turbine. To put this into perspective, a wind turbine 300 meters away is no noisier than the reading room of a library.

Shadow flicker is occasionally raised as an issue by close neighbors of wind farm projects. A wind turbine's moving blades can cast a moving shadow on nearby residence, depending on the time of year (which determines how low the sun is in the sky) and time of day. It is possible to calculate very precisely whether a flickering shadow will in fact fall on a given location near a wind farm, and how many hours in a year it will do so. Therefore, it should be easy to determine whether this is a potential problem. Normally it should not be a problem in the U.S., because at U.S. latitudes (except in Alaska) the sun's angle is not very low in the sky, and the appropriate setback for noise will be sufficient to prevent shadow flicker problems.

In open, flat terrain, a utility-scale wind plant will require about 60 acres per megawatt of installed capacity. However, only 5% (3 acres) or less of this area is actually occupied by turbines, access roads, and other equipment - 95% remains free for other compatible uses such as farming or ranching. In California, Minnesota, Texas, and elsewhere, wind energy provides rural landowners and farmers with a supplementary source of income through leasing and royalty arrangements with wind power developers.In open, flat terrain, a utility-scale wind plant will require about 60 acres per megawatt of installed capacity. However, only 5% (3 acres) or less of this area is actually occupied by turbines, access roads, and other equipment - 95% remains free for other compatible uses such as farming or ranching. In California, Minnesota, Texas, and elsewhere, wind energy provides rural landowners and farmers with a supplementary source of income through leasing and royalty arrangements with wind power developers.

It has been estimated by a number of reliable sources that 50,000 Americans a year die from air pollution, of which about one-third is produced by power plants. By contrast, in 20 years of operation, the wind industry (which emits no pollutants) has recorded only one death of a member of the public - a German skydiver who parachuted off-course into an operating wind plant. Blade throws were common in the industry's early years, but are unheard of today because of better turbine design and engineering. Ice throw, while it can occur, is of little danger because setbacks typically required to minimize noise are sufficient to protect against danger to the public, and because ice buildup slows a turbines rotation and will be sensed by the turbine's control system, causing the turbine to shut down. One European group that has investigated the ice throw question recommends a setback of 1.5 times the sum of a turbine's hub height and its rotor diameter.

No. There is nothing different or unusual about managing the electricity flow from an operating wind plant. Standard electric wiring practices are adequate to prevent stray voltage from occurring.

First, this is not a problem for modern small (residential) wind turbines. The materials used to make such machines ar non-metallic (composites, plastic, wood) and small turbines are too small to create electromagnetic interference (EMI) by "chopping up" a signal.

Large wind turbines, such as those typically installed at wind farms, can interfere with radio or TV signals if a turbine is in a "line of sight" between a receiver and the signal source, but this problem can usually be easily dealt with improving the receiver's antenna or installing relays to transmit the signal around the wind farm. Use of satellite or cable television is also an option.

Yes. Radar is basically designed to filter out stationary objects and display moving ones, and moving wind turbine blades create radar echoes. It is possible to modify a radar installation to eliminate this problem, according to a consulting firm that has studied it for the British government: According to the study: "This study concludes that radars can be modified to ensure that air safety is maintained in the presence of wind turbine farms. Individual circumstances will dictate the degree and cost of modification required, some installations may require no change at all whilst others may require significant modification."

If a wind project is proposed near an airport or military airfield, this issue will likely require further technical investigation. The interference is generally limited to objects (airplanes) that are physically shadowed by the turbines (that is, very low-flying aircraft), so the further the turbines are from an airfield and the lower their altitude, the less interference should occur.

Wind turbines can be sited offshore, where the wind blows harder and larger turbines can be installed. Many offshore wind farms are being proposed and developed today in densely populated Europe, where there is limited space on land and relatively large offshore areas with shallow water.

However, the urgent need to respond to climate change means that we will need to use as many renewable resources as we can, as quickly as possible, and that means both onshore and offshore wind. Also, the U.S. has very large onshore areas that are suitable for wind development, and not so much suitable offshore area.

Furthermore, since many people like the look of wind turbines, it should not be assumed that it would be more desirable to put all wind turbines far offshore. Onshore wind farms can provide significant economic development in the form of tax revenue to hard-pressed rural communities and rent payment to farmers. Onshore wind farms can therefore make a significant contribution to reducing and reversing the decline of rural communities that we have seen in the Plains States over the last several decades.

One of the largest offshore areas in the U.S. with shallow water is off Cape Cod, where a major wind farm has been proposed. Much of the rest of the U.S. coastline has at least some potential for wind development, but typically, turbine foundation costs increase rapidly with increasing water depth and wave height. The cost of connecting with utility power lines also increases rapidly as the distance from shore increases.

Still, there are advantages to building wind farms further offshore. Wind speeds tend to be higher and the wind is steadier. This means that turbines built further offshore should capture more wind energy. Many hope that the technical challenges will be overcome and that in the future offshore wind farms will be built much further offshore, perhaps even on floating platforms at sea.

Developers intentionally site wind turbines outside of established shipping lanes, thereby avoiding conflicts with routine traffic. Should a ship inadvertently go off course, its radar will readily detect the wind turbines, which are excellent radar reflectors. Wind turbines are also equipped with warning devices to alert ships in foul weather. The U.S. Coast Guard authorizes wind turbine locations for navigational concerns and determines the markings, lights, and fog signals needed.

Given the relatively small area of seabed that is required there is no evidence to suggest that total fish catch will decline as a result of wind farm developments; if anything the opposite is true. Fish stocks have been in decline for many years due to overfishing. Many environmental groups believe that wind farms will provide welcome sanctuary for fish spawning as well as refuge from intensive fisheries activity.

The wind industry is working actively with the fishing industry to ensure, as the oil and gas industry has done before it, that the fishing industry is not disadvantaged by the growth of offshore wind farms.

As with onshore turbines, offshore turbines are warranted and tested to withstand extreme wind conditions. In the event of severe weather, the blades turn out of the wind and will slow down for safety reasons when wind speeds reach 50 miles per hour and above.

Any proposed wind farm project will involve a full investigation of wave and coastal processes prior to construction. However, the turbine structures and distance offshore are such that it is very unlikely that would significantly affect the seabed or wave patterns. There is no evidence from the Danish experience with offshore wind farms of any detrimental effects on coastal processes.

The coastal erosion effects of higher sea levels and more extreme weather patterns due to global warming are already scientifically recognized, and far outweigh the potential effects of offshore wind farms.

There are three significant stages of a wind farm from the point of view of marine life: construction, operation and decommissioning. Construction and decommissioning have the potential to generate the most amount of disturbance, and the wind industry, as well as several marine conservation groups, is currently investigating these impacts on marine life.

However, it is important that such impacts be considered in the context of other marine activities such as fishing, shipping, oil and gas extraction, etc. Also, it should be noted that the duration of the construction and decommissioning will be about 6 months only. For the 20-year operational period there are no known impacts on marine life.

It has been suggested that the noise form wind turbines will travel underwater and could disturb sea life. But studies carried out on the impact of noise from existing offshore turbines note that the noise is very low frequency, and many species are actually unable to hear it.

As with any other local impact issues, these concerns will be addressed while a wind farm project is going through the permitting process.