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