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Q.What is wind energy?

The terms "wind energy" or "wind power" describe the process by which the wind is used to generate mechanical power or electricity. Wind turbines convert the kinetic energy of the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.

Q.How is the energy in the wind captured?

Wind turbines, like aircraft propeller blades, turn in the moving air and power an electric generator that supplies an electric current. Modern wind turbines are horizontal-axis variety, like the traditional farm windmills used for pumping water. Wind turbines are often grouped together into a single wind power plant, also known as a wind farm, and generate bulk electrical power. Electricity from these turbines is fed into a utility grid and distributed to customers just as it is with conventional power plants.

Q.How big are wind turbines?

Wind turbines are available in a variety of sizes, and therefore power ratings. Typical commercial wind facilities are 1.5 MW. The largest machine has blades that span more than the length of a football field, stands 20 building stories high, and produces enough electricity to power 1,400 homes. A small home-sized wind machine has rotors between 8 and 25 feet in diameter, stands upwards of 30 feet, and can supply the power needs of an all-electric home or small business.

Q.What are wind turbines made of?

All electric-generating wind turbines, no matter their size, are comprised of a few basic components: a rotor (the part that actually rotates in the wind), an electrical generator, a speed-control system, and a tower.

Q.Are there good wind resources in the United States?

Wind energy is very abundant in many parts of the United States. Wind resources are characterized by wind-power density classes, ranging from class 1 (the lowest) to class 7 (the highest). Good wind resources (e.g., class 3 and above, which have an average annual wind speed of at least 13 miles per hour) are found in many locations. Wind speed is a critical feature of wind resources, because the energy in wind is proportional to the cube of the wind speed. In other words, a stronger wind means a lot more power.

Q.How many homes can be powered by a megawatt of wind-generated electricity?

According to the American Wind Energy Association, 1 megawatt (MW) of wind-generated power can supply electricity to approximately 240 to 300 households per year.

Q.What are the advantages of wind-generated electricity?

Numerous public opinion surveys have consistently shown that the public prefers wind and other renewable energy forms over conventional sources of generation. Wind energy is a free, renewable resource, so no matter how much is used today, there will still be the same supply in the future. Wind energy is also a source of clean, non-polluting, electricity. Unlike conventional power plants, wind plants emit no air pollutants or greenhouse gases. According to the U.S. Department of Energy, in 1990, California's wind power plants offset the emission of more than 2.5 billion pounds of carbon dioxide and 15 million pounds of other pollutants that would have otherwise been produced. It would take a forest of 90 million to 175 million trees to provide the same air quality.

Q.What are the economic obstacles to greater wind power usage?

Even though the cost of wind power has decreased dramatically in the past 10 years, the technology requires a higher initial investment than fossil-fueled generators. Roughly 80% of the cost is the machinery, with the balance being for site preparation and installation. If wind generating systems are compared with fossil-fueled systems on a "life-cycle" cost basis (counting fuel and operating expenses for the life of the generator), however, wind costs are much more competitive with other generating technologies because there is no fuel to purchase and minimal operating expenses.

Q.Are there environmental problems facing wind power?

Although wind power plants have relatively little impact on the environment compared to fossil fuel power plants, there is some concern over the wildlife habitat impacts, noise produced by the rotor blades, aesthetic (visual) impacts, and bird and bat mortality. Most of these problems have been resolved or greatly reduced through technological development or by properly siting wind plants.

Q.Are wind turbines hazardous to birds and bats?

Bird and bat deaths are one of the most controversial biological issues related to wind turbines. The deaths of birds and bats at wind farm sites have raised concerns by fish and wildlife agencies and conservation groups. On the other hand, several large wind facilities have operated for years with only minor impacts on these animals.

To try to address this issue, the wind industry and government agencies have sponsored research into collisions, relevant bird and bat behavior, mitigation measures, and appropriate study design protocols. In addition, project developers are required to collect data through monitoring efforts at existing and proposed wind energy sites. Careful site selection is needed to minimize fatalities and in some cases additional research may be needed to address bird and bat impact issues.

While structures such as smokestacks, lighthouses, tall buildings, and radio and television towers have also been associated with bird and bat kills, bird and bat mortality is a serious concern for the wind industry.

Q.Are wind turbines noisy?

Most turbine noise is masked by the sound of the wind itself, and the turbines run only when the wind blows. Noise from wind turbines has diminished as the technology has improved. Early-model turbines are generally noisier than most new and larger models. As wind turbines have become more efficient, more of the wind is converted into rotational torque and less into acoustic noise. Under most conditions, modern turbines are quiet.

Q.Do wind turbines pose a safety hazard?

Unlike most other generation technologies, wind turbines do not use combustion to generate electricity, and hence don't produce air emissions. The only potentially toxic or hazardous materials are relatively small amounts of lubricating oils and hydraulic and insulating fluids. Therefore, contamination of surface or ground water or soils is highly unlikely. The primary health and safety considerations are related to blade movement and the presence of industrial equipment in areas potentially accessible to the public. Like all electrical generating facilities, wind generators produce electric and magnetic fields.

Q.Are there other drawbacks to the use of wind energy?

The major challenge to using wind as a source of power is that it is intermittent and does not always blow when electricity is needed. Wind cannot be stored (although wind-generated electricity can be, if batteries are used) and not all winds can be harnessed to meet the timing of electricity demands. Further, good wind sites are often located in remote locations far from areas of electric power demand (such as cities). Finally, wind resource development may compete with other uses for the land, and those alternative uses may be more highly valued than electricity generation.

Q.Is wind energy good for the economy?

Wind energy avoids the external or societal costs associated with conventional resources, namely, the trade deficit from importing foreign oil and other fuels, the health and environmental costs of pollution, and the cost of depleted resources. Wind energy is a domestic, reliable resource that provides more jobs per dollar invested than any other energy technology - more than five times that from coal or nuclear power, according to the U.S. Department of Energy. In 1994, wind-turbine and component manufacturers contributed directly to the economies of 44 states, creating thousands of jobs for Americans.

Q.Is the cost of wind power competitive with conventional power plants?

According to the U.S. Department of Energy, new, utility-scale wind projects are being built all around the United States today, with energy costs ranging from 3.9 cents per kilowatt-hour (at very windy sites in Texas) to 5 cents or more (in the Pacific Northwest). These costs are competitive with the direct operating costs of many conventional forms of electricity generation now - and prices are expected to drop even further over the next 10 years. Since wind is an intermittent electricity generator, and does not provide power on an "as needed" basis, it has to compare favorably with the costs saved on fuel from fossil generators.

Eason Zhong

Eason Zhong

Eason Zhong