FAQ / Wind Facts:
1. What are the benefits of wind energy? Unlike the processing and use of fossil fuels, there is no water, air, or thermal pollution. Wind energy is economically beneficial in that it provides price stability and a hedge against escalating fossil fuel prices in addition to being environmentally clean. As wind energy production becomes more efficient, costs will decline, while fossil fuel prices traditionally rise.
2. How does wind energy affect global warming? Global warming is a warming of the Earth’s surface and lower atmosphere, which is believed to be the result of an “enhanced greenhouse effect” mostly due to human-produced increases in atmospheric greenhouse gases. Wind energy does not emit greenhouse emissions, which is a fundamental cause of the greenhouse effect.
3. How does wind energy affect air pollution? Unlike the production of fossil fuels, wind energy does not produce toxic gases such as nitrogen oxide, sulphur oxide, and carbon dioxide. These gases seriously pollute the air and are main components of water pollution, health effects, and defoliate rain forests. Natural rain forests emit and absorb vast quantities of carbon dioxide, therefore induced deforestation, through fossil fuels, plays a significant role in causing rainforests to release carbon dioxide.
4. How does wind energy affect our water? The world is becoming increasingly water stressed. Most traditional methods of fossil fuel mining, extraction, and cooling use a vast amount of water. Wind energy uses virtually none of this precious commodity for the production of energy.
5. What other environmental effects does wind energy minimize? The dangers associated with the current fossil fuels used to generate electricity include exploration, mining, and subsequent soil erosion; pollution created by accidents; and associated health risks and cost. Additionally, the footprint of a turbine takes up a fraction of the land necessary to create electricity through the production of fossil fuels.
6. Do wind turbines provide electricity during a power outage? The answer to this question is two-fold. If the wind turbine is off the grid, meaning it is not connected to a public utility (grid), electricity will still be produced. If the wind turbine is connected to the grid, which is often the case, electricity will not be produced.
7. What type of noise is generated by wind energy turbines? Wind energy turbines are not noisy. The evolution of technology makes the noise almost undetectable with the main sound being the smooth swoosh of the blades passing over the tower. Strict manufacturer guidelines allow for noise emissions to either meet or exceed residential amenity ordinances. Decibel (dB) levels do increase slightly as you add other wind turbines that are a factor of wind farms and groups of turbines sited along ridges with side slopes.
> Comparison of sound pressure and levels
8. Does low-frequency noise from wind turbines pose any health concerns?Measurements of wind turbine noise undertaken in Germany, Denmark, the United Kingdom, and the United States over the past decade, and accepted by experienced noise professionals, have shown that the levels of infrasonic noise and vibration radiated from modern, upwind configuration wind turbines are at a very low level; so low that they lie below the threshold of perception, even for those people who are particularly sensitive to such noise, and even on an actual wind turbine site.
> BWEA Low Frequency Noise and Wind Turbines
9. Are farm livestock affected by wind energy turbines? Wind farming has been used over the years on the agricultural footprint to augment the energy expenses attributable to farming. Livestock are not disturbed by a wind energy turbine.
10. Does a wind turbine disrupt agriculture? The space required allows the farmers the continual maximization of farm land since it takes up a fraction of the land they are sited on. As part of the site determination, wind turbines are located in a way that facilitates the continuation of farming.
11. Do wind turbines kill birds? The vast majority of research shows that wind turbines kill relatively few birds compared with other causes such as utility lines, windows, pesticides, motor vehicles, lighted communication towers, cats, and extraction of fossil fuels. The most noteworthy threat to birds and their habitats comes from climate change conditions and the loss of their respective natural habitat.
12. Do wind turbines kill bats? Bats killed by wind turbines are predominately species that rely on trees as roosts throughout the year and migrate long distances; these species are called “migratory tree bats.” Currently, migratory tree bats compose more than three-quarters of the bat fatalities observed at wind energy sites. The other striking pattern is that the vast majority of bat fatalities at wind turbines occur during late summer and autumn. Hoary bats are one of the most frequently killed migratory species at wind turbines. The hoary bats live in forests of the eastern U.S. and in arid deserts of the Southwest, and are most abundant in the forests and croplands of the Plains states and in forests of the Pacific Northwest.
13. How does the wind generate electricity? Wind energy turns the turbine blades, thereby rotating an electronic generator. The generator spawns DC (Direct Current) electricity, which through a power converter is turned into AC (Alternating Current) electricity.
14. Are wind energy turbines supported by any environmental groups? Both the Sierra Club and the Audubon Society support wind energy turbines.
15. Are there any offshore wind projects? To date, no offshore wind projects have been built in the U.S., although the first ones are scheduled for 2014 in New England. Denmark, Ireland, Sweden, The Netherlands, and the United Kingdom currently have offshore wind turbines.
16. How safe are wind energy turbines? Wind energy turbines are one of the safest energy technologies. They have been in operation nationwide over the past 25 years. As a matter of record, no injuries have been attributed to the normal operation of the turbines.
17. How big are medium- to large-scale wind energy turbines? The towers range in height from 25 to 100 meters. The rotor diameters range from 30 to 80 meters.
18. How strong must the wind be for the medium- to large-scale wind energy turbines to function? Wind energy turbines begin operation at wind speeds of 4 to 5 meters per second or roughly 10 miles per hour.
19. What is the life expectancy of a wind energy turbine? Wind energy turbines last approximately 20 to 25 years with regular maintenance.
20. What happens when a wind energy turbine is decommissioned?Traditionally the parameters for decommissioning are covered by clauses established during the planning permission phase of construction with the local municipal authorities. This would involve defining the discontinuance of operation, the timeframe associated with the physical turbine removal, and the restoration of the site to its preconstruction phase.
21. What is shadow flicker? Shadow flicker is the resulting effect of the turbine blades rotating in low-angle sun. It is the alternating changes in light intensity caused by the moving blade thereby casting shadows on the ground and stationary objects. No shadow flicker is cast when the sun is obscured by clouds/fog or when the turbine is not rotating. In the analysis phase of project development, a review should be performed to determine the impact of shadow flicker and placement of the turbine(s) to lessen or eliminate the impact.
22. Do wind turbines throw ice? Wind turbines, similar to any structure, may accumulate ice under certain atmospheric conditions. The accumulation of ice would be dependent on local weather conditions and the turbine’s operational state. Ice accumulated may be shed or thrown from the turbine due to both the mechanical forces of the rotating blades and gravity.
To mitigate ice throw, wind turbines can be deactivated remotely, switching off the turbine when ice accumulation is detected. Depending on the model, automatic shutdowns (braking) are effectuated by the detection of rotor imbalance caused by blade ice formation or icing that leads to a measured wind speed below cut-in. Ice fragments that fall from a stopped rotor will break into smaller parts on the way to the ground.
23. How frequently do wind turbines produce electricity? A modern wind energy turbine produces electricity between 65 to 80% of the time. During this period, it will generate different outputs depending on the wind speed, which blows steadily at times and not at all at other times, thereby running at less than full capacity. A capacity factor of 25 to 40% is common, although the turbine may achieve higher capacity during windy weeks or months. Wind speeds are generally higher during the fall and winter months, tapering off late spring and summer.
24. How do you determine which wind turbine to use once a site has been selected? Selection of the wind turbine depends on multiple variables, such as: the wind resource, project goals, wind turbine availability, project costs, and reliability.
25. What is net metering? Net metering is an electricity policy for consumers who own renewable energy facilities, such as wind, solar power, or home fuel cells. “Net,” in this context, is used in the sense of meaning “what remains after deductions” — in this case, the deduction of any energy outflows from metered energy inflows. Under net metering, a system owner receives retail credit for at least a portion of the electricity they generate. Customers would be billed only for the net energy consumed during the billing period.
26. Are there state and local laws governing the erection of a wind turbine?Many states and local municipalities have ordinances governing the erection of tall structures or wind turbines. Research of these laws should be undertaken as part of any decision regarding wind turbines.
27. Are there any incentives or rebate programs available where I live? The U.S. Department of Energy maintains a database of state incentives for renewable energy and efficiency, entitled DSIRE. > http://dsireusa.org
28. What is the payback period for a medium to large wind turbine? Payback would be site specific based on several variables such as the topographical survey, wind profile, height of hub, turbine lifecycle, energy output, and overall cost.
29. Do wind turbines affect property values? A three-year study by the U.S. Department of Energy’s Lawrence Berkeley National Laboratory concludes “neither the view of wind energy facilities nor the distance of the home to those facilities was found to have any consistent, measurable, and significant effect on the selling prices of nearby homes. No matter how we looked at the data, the same result kept coming back – no evidence of widespread impacts.” > U.S. Department of Energy, Dec. 2009
30. Do wind turbines affect individuals who have epileptic seizures? Epilepsy Action performed a survey in 2007 to determine whether wind turbines can trigger seizures in people with epilepsy. It was available on their website for one month and advertised through Epilepsy Action’s newsletters and online community. Twenty six people responded to the survey and only one of them reported that they had a seizure brought on while looking at a wind turbine. However, since this person did not have photosensitive epilepsy, it was difficult to conclude whether or not the seizure was actually caused by the wind turbine.
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