| What is a wind turbine and how does it work? | | | | sources of income. Best of all, wind powers the |
| A wind energy system transforms the kinetic energy | | | | economy without causing pollution, generating |
| of the wind into mechanical or electrical energy that | | | | hazardous wastes, or depleting natural resources. |
| can be harnessed for practical use. Mechanical energy | | | | What are America's current sources of electricity? |
| is most commonly used for pumping water in rural or | | | | Coal, the most polluting fuel and the largest source of |
| remote locations. Wind electric turbines generate | | | | the leading greenhouse gas, carbon dioxide (CO2), is |
| electricity for homes and businesses and for sale to | | | | currently used to generate more than half of all of the |
| utilities. | | | | electricity (52%) used in the United States. Other |
| There are two basic designs of wind electric turbines: | | | | sources of electricity are: natural gas (15%), oil (4%), |
| vertical-axis, or "egg-beater" style, and horizontal-axis | | | | nuclear (19%), and hydropower (9%). |
| machines. Horizontal-axis wind turbines are most | | | | How many people work in the U.S. wind industry? |
| common, comprising more than 95% of the | | | | The U.S. wind industry currently directly employs more |
| "utility-scale" (100 kilowatts (kW) capacity and larger) | | | | than 2,000 people. The wind industry contributes |
| turbine market. | | | | directly to the economies of 46 states, with power |
| Turbine subsystems include: | | | | plants and manufacturing facilities that produce wind |
| a rotor, or blades, which convert the wind's energy into | | | | turbines, blades, electronic components, gearboxes, |
| rotational shaft energy; | | | | generators, and a wide range of other equipment. |
| a nacelle containing a drive train, usually including a | | | | The European Wind Energy Association (EWEA) |
| gearbox* and a generator; | | | | estimates that every megawatt of installed wind |
| a tower, to support the rotor and drive train; and | | | | capacity creates about 60 person-years of |
| electronic equipment such as controls, electrical cables, | | | | employment and 15-19 jobs, directly and indirectly. A |
| ground support equipment, and interconnection | | | | typical 50-MW wind farm, therefore, creates some |
| equipment. | | | | 3,000 person-years of employment. The rate of job |
| Some turbines operate without a gearbox. | | | | creation will decline as the industry grows and |
| Wind turbines vary in size. This chart depicts a variety | | | | becomes able to make more use of efficiencies of |
| of turbine sizes and the amount of electricity they are | | | | volume, but wind and solar energy are still likely to |
| each capable of generating (the turbine's capacity, or | | | | furnish one of the largest sources of new |
| power rating). | | | | manufacturing jobs worldwide during the 21st Century. |
| How much electricity can one wind turbine generate? | | | | What is the value of export markets for wind? |
| The ability to generate electricity is measured in watts. | | | | Export markets are growing rapidly. Overseas |
| Watts are very small units, so the terms kilowatt (1,000 | | | | markets account for about half of the business of U.S. |
| watts), megawatt (1 million watts), and gigawatt (1 billion | | | | manufacturers of small wind turbines and wind energy |
| watts) are most commonly used to describe the | | | | developers. Small wind turbine markets are diverse |
| capacity of generating units like wind turbines or other | | | | and include many applications, both on-grid (connected |
| power plants. | | | | to a utility system) and off-grid (stand-alone). A recent |
| Electricity production and consumption are most | | | | market study predicts that small wind turbine sales will |
| commonly measured in kilowatt-hours (kWh). A | | | | increase fivefold by 2005. |
| kilowatt-hour means 1,000 watts of electricity produced | | | | The potential economic benefits from wind are |
| or consumed for one hour. One 50-watt light bulb left | | | | enormous. At a time when U.S. manufacturing |
| on for 20 hours consumes one kilowatt-hour of | | | | employment is generally on the decline, the production |
| electricity (50 watts x 20 hours = 1,000 watt-hours = 1 | | | | of wind equipment is one of the few potentially large |
| kilowatt-hour). | | | | sources of new manufacturing jobs on the horizon. |
| The output of a wind turbine depends on the turbine's | | | | AWEA has estimated that wind installations worldwide |
| size and the wind's speed through the rotor. Wind | | | | will total more than 48,000 megawatts over the next |
| turbines being manufactured now have power ratings | | | | decade, or more than $45 billion worth of business. If |
| ranging from 250 watts to 1.65 megawatts (MW). | | | | the U.S. industry could capture a 25% share of the |
| Example: A 10-kW wind turbine can generate about | | | | global wind market through the year 2010, more than |
| 16,000 kWh annually, more than enough to power a | | | | 150,000 new jobs would be created. |
| typical household. A 1.65-MW turbine can produce | | | | In what other ways does wind energy benefit the |
| more than 4.7 million kWh in a year--enough to power | | | | economy? |
| more than 470 households. The average U.S. | | | | Wind farms can revitalize the economy of rural |
| household consumes about 10,000 kWh of electricity | | | | communities, providing steady income through lease or |
| each year. | | | | royalty payments to farmers and other landowners. |
| Example: A 250-kW turbine installed at the elementary | | | | Although leasing arrangements can vary widely, a |
| school in Spirit Lake, Iowa, provides an average of | | | | reasonable estimate for income to a landowner from |
| 350,000 kWh of electricity per year, more than is | | | | a single utility-scale turbine is about $2,000 a year. For |
| necessary for the 53,000-square-foot school. Excess | | | | a 250-acre farm, with income from wind at about $55 |
| electricity fed into the local utility system has earned | | | | an acre, the annual income from a wind lease would |
| the school $25,000 over five years. The school uses | | | | be $14,000, with no more than 2-3 acres removed |
| electricity from the utility at times when the wind does | | | | from production. Farmers can grow crops or raise |
| not blow. | | | | cattle next to the towers. Wind farms may extend |
| Wind speed is a crucial element in projecting turbine | | | | over a large geographical area, but their actual |
| performance, and a site's wind speed is measured | | | | "footprint" covers only a very small portion of the land, |
| through wind resource assessment prior to a wind | | | | making wind development an ideal way for farmers to |
| system's construction. Generally, annual average wind | | | | earn additional income. In west Texas, for example, |
| speeds greater than four meters per second (m/s) (9 | | | | farmers are welcoming wind, as lease payments from |
| mph) are required for small wind electric turbines (less | | | | this new clean energy source replace declining |
| wind is required for water-pumping operations). | | | | payments from oil wells that have been depleted. |
| Utility-scale wind power plants require minimum | | | | Farmers are not the only ones in rural communities to |
| average wind speeds of 6 m/s (13 mph). | | | | find that wind power can bring in income. In Spirit Lake, |
| The power available in the wind is proportional to the | | | | Iowa, the local school is earning savings and income |
| cube of its speed, which means that doubling the wind | | | | from the electricity generated by a turbine. In the |
| speed increases the available power by a factor of | | | | district of Forest City, Iowa, a turbine recently erected |
| eight. Thus, a turbine operating at a site with an | | | | as a school project is expected to save $1.6 million in |
| average wind speed of 12 mph will generate about | | | | electricity costs over its lifetime. |
| 29% more electricity than one at an 11-mph site. | | | | Additional income is generated from one-time |
| How many turbines does it take to make one | | | | payments to construction contractors during installation, |
| megawatt (MW)? | | | | and from payments to turbine maintenance personnel |
| Most manufacturers of utility-scale turbines offer | | | | on a long-term basis. Wind farms also expand the local |
| machines in the 700-kW to 1.65-MW range. Ten | | | | tax base, and keep energy dollars in the local |
| 700-kW units would make a 7-MW wind plant, while 10 | | | | community instead of spending them to pay for coal |
| 1.65-MW machines would make a 16.5-MW facility. In | | | | or gas produced elsewhere. Alameda (Calif.) County, |
| the future, machines of larger size will be available. | | | | for example, collected $725,000 in property taxes |
| What is a wind power plant? | | | | during 1998 from wind turbine installations valued at |
| Wind plants can range in size from a few megawatts | | | | $66 million. |
| to hundreds of megawatts in capacity. Wind power | | | | Wind energy and the environment |
| plants are "modular," which means they consist of | | | | What are the environmental benefits of wind power? |
| small individual modules (the turbines) and can easily be | | | | Wind energy system operations do not generate air or |
| made larger or smaller as needed. Turbines can be | | | | water emissions and do not produce hazardous |
| added as electricity demand grows. Today, a 50-MW | | | | waste. Nor do they deplete natural resources such as |
| wind farm can be completed in 18 months (including | | | | coal, oil, or gas, or cause environmental damage |
| resource assessment). | | | | through resource extraction and transportation. Wind's |
| What is "capacity factor"? | | | | pollution-free electricity can help reduce the |
| A conventional utility power plant uses fuel, so it will | | | | environmental damage caused by power generation in |
| normally run much of the time unless it is idled by | | | | the U.S. and worldwide. |
| equipment problems or for maintenance. A capacity | | | | In 1997, U.S. power plants emitted 70% of the sulfur |
| factor of 40% to 80% is typical for conventional plants. | | | | dioxide, 34% of carbon dioxide, 33% of nitrogen |
| A wind plant is "fueled" by the wind, which blows | | | | oxides, 28% of particulate matter and 23% of toxic |
| steadily at times and not at all at other times. Most | | | | heavy metals released into our nation's environment, |
| modern utility-scale wind turbines operate with a | | | | mostly the air. These figures are currently increasing in |
| capacity factor of 25% to 40%, although they may | | | | spite of efforts to roll back air pollution through the |
| achieve higher capacity factors during windy weeks or | | | | federal Clean Air Act. |
| months. It is possible to achieve much higher capacity | | | | Sulfur dioxide and nitrogen oxides cause acid rain. Acid |
| factors by combining wind with a storage technology | | | | rain harms forests and the wildlife they support. Many |
| such as pumped hydro or compressed-air energy | | | | lakes in the U.S. Northeast have become biologically |
| storage (CAES). | | | | dead because of this form of pollution. Acid rain also |
| What is "availability factor"? | | | | corrodes buildings and economic infrastructure such as |
| Availability factor (or just "availability) is a measurement | | | | bridges. |
| of the reliability of a wind turbine or other power plant. | | | | Carbon dioxide (CO2) is a greenhouse gas--its buildup |
| It refers to the percentage of time that a plant is ready | | | | in the atmosphere contributes to global warming by |
| to generate (that is, not out of service for maintenance | | | | trapping the sun's rays on the earth as in a |
| or repairs). Modern wind turbines have an availability of | | | | greenhouse. The U.S., with 5% of the world's |
| more than 98%--higher than most other types of | | | | population, emits 23% of the world's CO2. The build-up |
| power plant. After two decades of constant | | | | of greenhouse gases is not only causing a gradual rise |
| engineering refinement, today's wind machines are | | | | in average temperatures, but also seems to be |
| highly reliable. | | | | increasing fluctuations in weather patterns and causing |
| Wind energy costs | | | | more severe droughts. |
| How much does wind energy cost? | | | | Particulate matter is of growing concern because of |
| The National Renewable Energy Laboratory (NREL) is | | | | its impacts on health. Its presence in the air along with |
| working with the wind industry to develop a next | | | | other pollutants has contributed to make asthma one |
| generation of wind turbine technology. The products | | | | of the fastest growing childhood ailments in industrial |
| from this program are expected to generate electricity | | | | and developing countries alike. Toxic heavy metals |
| at prices competitive with natural gas turbines, the | | | | accumulate in the environment and up the biological |
| least expensive conventional power source. | | | | food chain. |
| How do utility-scale wind power plants compare in | | | | Development of 10% of the wind potential in the 10 |
| cost to other renewable energy sources? | | | | windiest U.S. states would provide more than enough |
| Wind is the low-cost emerging renewable energy | | | | energy to displace emissions from the nation's |
| resource. | | | | coal-fired power plants and eliminate the nation's major |
| What is the "production tax credit" for wind energy? | | | | source of acid rain; reduce total U.S. emissions of CO2 |
| Generally, the credit is a business credit that applies to | | | | by almost a third and world emissions of CO2 by 4 %; |
| electricity generated from wind plants for sale at | | | | and help contain the spread of asthma and other |
| wholesale (i.e., to a utility or other electricity supplier). It | | | | respiratory diseases aggravated or caused by air |
| applies to electricity produced during the first 10 years | | | | pollution in this country. |
| of a wind plant's operation. | | | | If wind energy were to provide 20% of the nation's |
| The wind PTC expired June 30, 1999, and an effort is | | | | electricity--a very realistic and achievable goal with the |
| currently underway to extend it for five years. For | | | | current technology--it could displace more than a third |
| information on the status of that effort, contact the | | | | of the emissions from coal-fired power plants, or all of |
| American Wind Energy Association (AWEA), phone | | | | radioactive waste and water pollution from nuclear |
| (202) 383-2500, e-mail <windmail@awea.org>>. | | | | power plants. |
| Wind energy's potential | | | | The 6 billion kilowatt-hours currently generated by wind |
| The wind doesn't blow all the time. How much can it | | | | plants in the U.S. each year displaced some 9 billion |
| really contribute to a utility's generating capacity? | | | | pounds (4.5 million tons) of carbon dioxide, 23,500 tons |
| However, in two separate studies, researchers have | | | | of sulfur dioxide (64 tons per day), and 15,500 tons of |
| found that despite its intermittent nature, wind can | | | | nitrogen oxides (42 tons per day). |
| provide capacity value for utilities. | | | | What are wind power's other environmental impacts? |
| The studies, by the Tellus Institute of Boston, Mass., | | | | Wind power plants, like all other energy technologies, |
| and the Prince Edward Island (Canada) Energy Corp., | | | | have some environmental impacts. However, unlike |
| concluded that when wind turbines are added to a | | | | most conventional technologies (which have regional |
| utility system, they increase the overall statistical | | | | and even global impacts due to their emissions), the |
| probability that the system will be able to meet | | | | impacts of wind energy systems are local. This makes |
| demand requirements. They noted that while wind is | | | | them easier for local communities to monitor and, if |
| an intermittent resource, conventional generating | | | | necessary, mitigate. |
| systems also experience periodic outages for | | | | The local environmental impacts that can result from |
| maintenance and repair. | | | | wind power development include: |
| The exact amount of capacity value that a given wind | | | | Erosion, which can be prevented through proper |
| project provides depends on a number of factors, | | | | installation and landscaping techniques. Erosion can be |
| including average wind speeds at the site and the | | | | a concern in certain habitats such as the desert, |
| match between wind patterns and utility load | | | | where a hard-packed soil surface must be disturbed |
| requirements. | | | | to install wind turbines. |
| How much energy can wind realistically supply to the | | | | Bird kills and other effects. Birds occasionally collide |
| U.S.? | | | | with wind turbines, as they do with other tall structures |
| Wind energy could supply about 20% of the nation's | | | | such as buildings. Avian deaths have become a |
| electricity, or 600 billion kilowatt-hours annually, | | | | concern at Altamont Pass in California, which is an |
| according to Battelle Pacific Northwest Laboratory, a | | | | area of extensive wind development and also high |
| federal research lab. Wind energy resources useful for | | | | year-round raptor use. Detailed studies at other wind |
| generating electricity can be found in nearly every | | | | development areas indicate that this is a site-specific |
| state. | | | | issue that will not be a problem at most potential wind |
| U.S. wind resources are even greater, however. North | | | | sites. However, areas that are commonly used by |
| Dakota alone is theoretically capable (if there were | | | | threatened or endangered species should be regarded |
| enough transmission capacity, storage capability, etc.) | | | | as unsuitable for wind development. The wind industry |
| of producing enough wind-generated power to meet | | | | is working with environmental groups, federal |
| more than one-third of U.S. electricity demand. The | | | | regulators, and other interested parties to develop |
| theoretical potentials of the windiest states are shown | | | | methods of measuring and mitigating wind energy's |
| in the following table. | | | | effect on birds. |
| Experience also shows that wind power can provide | | | | Visual impacts, which can be minimized through careful |
| at least up to a fifth of a system's electricity, and the | | | | design of a wind power plant. Using turbines of the |
| figure could probably be higher. Wind power currently | | | | same size and type and spacing them uniformly |
| provides more than 20% of the electricity distributed | | | | generally results in a wind plant that satisfies most |
| by Energia Hidroelectrica de Navarra, the regional | | | | aesthetic concerns. Computer simulation is helpful in |
| electric utility of the industrial state of Navarra in | | | | evaluating visual impacts before construction begins. |
| northern Spain. In western Denmark, wind supplies | | | | Public opinion polls show that the vast majority of |
| more than 25% of the electricity that is used during | | | | people favor wind energy, and support for wind plants |
| windy winter nights. | | | | often increases after they are actually installed and |
| How much energy can wind supply worldwide? | | | | operating. |
| According to the U.S. Department of Energy, the | | | | Noise was an issue with some early wind turbine |
| world's winds could theoretically supply the equivalent | | | | designs, but it has been largely eliminated as a problem |
| of 5,800 quadrillion BTUs (quads) of energy each | | | | through improved engineering and through appropriate |
| year--more than 15 times current world energy | | | | use of setbacks from nearby residences. |
| demand. (A quad is equal to about 172 million barrels of | | | | Aerodynamic noise has been reduced by adjusting the |
| oil or 45 million tons of coal.) | | | | thickness of the blades' trailing edges and by orienting |
| A recent study performed by Denmark's BTM Consult | | | | blades upwind of the turbine tower. A small amount of |
| for the European Wind Energy Association and | | | | noise is generated by the mechanical components of |
| Greenpeace found that by the year 2017, wind could | | | | the turbine. To put this into perspective, a wind turbine |
| provide 10% of world electricity supplies, meeting the | | | | 250 meters from a residence is no noisier than a |
| needs of 500 million average European households. | | | | kitchen refrigerator. |
| The potential of wind to improve the quality of life in | | | | How much land is needed for a utility-scale wind plant? |
| the world's developing countries, where more than two | | | | In open, flat terrain, a utility-scale wind plant will require |
| billion people live with no electricity or prospect of utility | | | | about 50 acres per megawatt of installed capacity. |
| service in the foreseeable future, is vast. | | | | However, only 5% (2.5 acres) or less of this area is |
| What is the "energy payback time" for a wind turbine? | | | | actually occupied by turbines, access roads, and other |
| The "energy payback time" is a term used to measure | | | | equipment--95% remains free for other compatible |
| the net energy value of a wind turbine or other power | | | | uses such as farming or ranching. In California, |
| plant--i.e., how long does the plant have to operate to | | | | Minnesota, Texas, and elsewhere, wind energy |
| generate the amount of electricity that was required | | | | provides rural landowners and farmers with a |
| for its manufacture and construction? Several studies | | | | supplementary source of income through leasing and |
| have looked at this question over the years and have | | | | royalty arrangements with wind power developers. |
| concluded that wind energy has one of the shortest | | | | A wind plant located on a ridgeline in hilly terrain will |
| energy payback times of any energy technology. A | | | | require much less space, as little as two acres per |
| wind turbine typically takes only a few months (3-8, | | | | megawatt. |
| depending on the average wind speed at its site) to | | | | How much water do wind turbines use compared with |
| "pay back" the energy needed for its fabrication, | | | | conventional power plants? |
| installation, operation and retirement. | | | | Water use can be a significant issue in energy |
| Wind energy and the economy | | | | production, particularly in areas where water is scarce, |
| What does the U.S. wind industry contribute to the | | | | as conventional power plants use large amounts of |
| economy? | | | | water for the condensing portion of the |
| Wind power supplies affordable, inexhaustible energy | | | | thermodynamic cycle. For coal plants, water is also |
| to the economy. It also provides jobs and other | | | | used to clean and process fuel. |