Quell'insopportabile baccano delle turbine eoliche

 Stabilimento di produzione Siemens Wind Power (DK). Foto di Francesco Paraggio, www.ventofavorevole.org

Su TheOilDrum* è recentemente comparso un link a un articolo, che riporto sotto, in cui viene trattato l'impatto acustico dei generatori eolici.

 La sostanza è:

- il rumore delle turbine, dovuto al moto aerodinamico delle pale nell'aria, è del tutto confondibile con qualunque rumore dell'ambiente urbano e suburbano

- le turbine emettono un suono a bassa frequenza. Gli esperti di acustica concordano sul fatto che tale rumore non è dannoso per la salute. Se lo fosse, la vita urbana sarebbe impossibile, essendo esposta a ben altri livelli di pressione sonora.

Per la mia limitata esperienza, avendo visto solo un paio di wind farms, posso asserire di non aver avvertito rumori fastidiosi. Le turbine eoliche sono sistemate in zone ventose, il rumore che l'aria fa soffiando sui padiglioni auricolari copre del tutto quello legato alla rotazione delle pale.
Per chi volesse un approccio visivo, qui trovate un link a un video degli impianti funzionanti a Garessio, in provincia di Cuneo. Qui, invece, rilinko un post su un filmato che avevo fatto 1 anno fa a Bezier.
Consiglio anche la lettura di questo post, traduzione di Francesco Paraggio.

Più avanti, magari, faremo un post in cui si parlerà di un'altra leggenda, quella secondo cui le turbine eoliche fanno strage di stormi di uccelli. Stay tuned **.

* Secondo la mia modesta opinione, theoildrum è uno dei siti di punta che dovrebbe avere in linkoteca chiunque voglia capire i meccanismi e le dinamiche degli eventi dei prossimi lustri

** Preoccuparsi di falsi problemi, con la consapevolezza di un possibile crunch energetico ed economico nella prossima decade, è al tempo stesso demenziale ed incredibile. Una vera opera del demonio

The facts about wind turbine sound

By JOHN DUNLOP
Last update: October 11, 2009 - 9:31 AM

I would much rather have a wind turbine farm as a neighbor instead of the guy living on a farm on 280th Street in southern Scott county. He must have 20 some huge white signs set up along the highway claiming wind turbines are evil. Talk about rural blight.
Minnesota is one of the 10 windiest states in the country. It pioneered the new wave of wind power development in the 1990s. Today, it is the state that generates the largest share of its electricity from wind (7.48 percent in 2008, according to American Wind Energy Association), and it ranks fourth in installed wind-power generating capacity, after Texas, Iowa and California. Nationally, wind power has become one of our economy's mainstream electricity sources, accounting for 42 percent of the generating capacity added last year to power homes, offices and businesses. Yet it seems that when new wind farms are proposed, questions are still sometimes raised about the potential impact. We welcome the opportunity to set the record straight, based on the widespread experience that communities and the wind energy industry now have in the United States and across the globe.
Wind turbine sounds are no different from other sounds present in a suburban or urban environment. The sound of a turbine is mainly due to the aerodynamic swish of the blades rotating in the air.
Turbines can also emit some low-frequency sound. Acoustical experts agree there is no evidence that such sounds, which are emitted by a variety of sources, could be harmful to health -- indeed, if these levels were so harmful, urban dwelling would be impossible.
In short, turbine sound is quieter than many ambient sounds and is equally safe, and while some people may be disturbed by even a relatively quiet sound, the reality is that thousands of turbines have been successfully integrated with communities throughout the country.
Wind turbines are one of the most environmentally benign forms of electricity generation and allow most preexisting land uses -- typically ranching and farming -- to continue as before. As many farmers nationwide can attest, cows graze up to the foot of the turbines and on some days even use them for shade. Wind turbines safely operate on schoolyards.
Because turbines operate in so many locations and circumstances, the industry believes setbacks are best assessed on a case-by-case basis. Many permitting agencies have, however, established minimum required setbacks from residences, public roads and adjacent property lines. In instances where no required setbacks have been established, developers will work with local stakeholders during the siting and design phase of a project to determine what's appropriate.
Lights are needed on wind turbines to ensure air traffic safety under Federal Aviation Administration standards. The industry has worked with the FAA to develop guidelines aimed at reducing the number of lights while maintaining air safety. Typically, lights on the turbines around the perimeter of a wind farm will be sufficient.
As our economy grows and as we become ever more dependent on electricity for a range of uses, it's clear that our electricity must come from somewhere. Some of the best winds in the world blow across the American landscape, and installing wind turbines is an efficient way to capture that energy.
A report released just last year by the U.S. Department of Energy confirmed that wind power could generate 20 percent of the nation's electricity by 2030 -- a share as large as that of nuclear power today -- and that this level is not a limit. The report found no technical or macroeconomic barriers. The economic benefits alone include more income for landowners (and thus for communities) and more stability in electricity prices as a larger share of our electricity becomes immune to the impacts of fuel price volatility.
We invite people to stop at a wind farm to see and hear for themselves. You can find projects along Interstate 90 south of Rochester and further west, in southwestern Minnesota northwest of Worthington, or in numerous other spots around the country. Stop, shut off the car, get out, look and listen. You'll hear the gentle swoosh of the blades and see the power of wind in action.
Wind turbines are indeed a change in our landscape. They are the symbol of our clean and healthy energy future.
John Dunlop is a senior project engineer with the American Wind Energy Association.