NOISE RESEARCH TO COMBAT WIND TURBINE SYNDROME
June 1, 2011
“Wind turbine noise is very directional. Someone living at the base might not have a problem but two kilometres away, it might be keeping them awake at night,”
“Wind turbine noise is controversial but there’s no doubt that there is noise and that it seems to be more annoying than other types of noise at the same level.
University of Adelaide acoustics researchers are investigating the causes of wind turbine noise with the aim of making them quieter and solving ‘wind turbine syndrome’.
They are also developing a computer model to predict the noise output from wind farms so they can accurately and quickly assess the effectiveness of potential noise-reducing designs and control methods.
Research leader Dr Con Doolan, of the University’s School of Mechanical Engineering, said the noise generated from wind turbines is ‘trailing edge or airfoil noise’, the same sort of noise generated at the edge of aircraft wings.
“We know generally what causes that noise – as the turbulent air flows over the sharp edge of the blade it radiates sound much more efficiently, so the noise can be heard at some distance,” said Dr Doolan.
“What we don’t yet understand, however, is exactly how that turbulence and blade edge, or boundary layer, interact and how that makes the noise louder.
“If we can understand this fundamental science, we can then look at ways of controlling the noise, through changing the shape of the rotor blades or using active control devices at the blade edges to disrupt the pattern of turbulence and so reduce the noise.”
Dr Doolan said further complicating factors came from the effects of multiple wind turbines together and the way the noise increases and decreases as the blades rotate – the blade ‘swish’. The model they are developing will look at the noise from the whole wind turbine and how multiple numbers of wind turbines together, as in a wind farm, generate noise.
“Wind turbine noise is very directional. Someone living at the base might not have a problem but two kilometres away, it might be keeping them awake at night,” he said.
“Likewise this broadband ‘hissing’ noise modulates up and down as the blades rotate and we think that’s what makes it so annoying,” he said.
“Wind turbine noise is controversial but there’s no doubt that there is noise and that it seems to be more annoying than other types of noise at the same level. Finding ways of controlling and reducing this noise will help us make the most of this very effective means of generating large amounts of electricity with next to zero carbon emissions.”
Something from the Wind Developer's point of view
IS WIND ENERGY THE NEW WEDGE ISSUE?
SOURCE: North American Windpower
By Jeff Siegel,
Almost as soon as the situation at Japan’s Fukushima Daiichi nuclear plant became critical in March, Fox News reported that wind power had killed more Americans than nuclear energy. Meanwhile, the Texas Public Policy Foundation, a conservative think tank, issued a study that said the state’s taxpayers would be $28 billion better off if Texas abandoned its pro-wind policies.
Wind, after being the darling of the media, business and state governments for much of its history, has suddenly found itself on the receiving end of negative publicity, questions about its value as an energy source and even calls for an end to wind development. The feel-good “green” story, according to the New York Times, “is now nearing extinction.”
Texas, Wisconsin and Minnesota, all considered wind-friendly states, have recently pursued policies that can be seen as anti-wind.
Some of this shift is due to the industry’s natural maturation process, according to David Lowman, an attorney who is co-chair of Hunton & Williams’ global renewable energy practice group in Washington, D.C.
Some of the backlash against wind also stems from the recession, which has not only hampered wind development but has made even previously wind-friendly regulators and legislators question its cost at a time when state and federal budgets are being slashed.
The pushback, says attorney Jim Tynion, who chairs Foley & Lardner’s energy industry team, is genuine and something that the industry needs to address.
The acrimony is being powered by a combination of small-government conservatives who see wind and other renewables as a waste of money and by others who consider wind a technology that will never be as effective as oil, coal or natural gas.
During a Texas ground-breaking ceremony for an oil and gas processing company, Sen. John Cornyn, R-Texas, told KSAT in San Antonio, “I understand that some people want to see green jobs; I think that’s great. We need all of the above when it comes to energy: wind, solar, biofuels and the like. But the fact of the matter is 85 percent of our fuel consumption comes from fossil fuels.”
Cornyn’s comments underscore the political realities that wind energy faces.
“The political landscape has changed,” Tynion says. “It’s easy to take potshots at something that isn’t part of the status quo, like wind. It has become an easy target.”
Certainly, not all has gone badly for wind. The American Wind Energy Association (AWEA) estimates that the U.S. wind power industry grew by 15% in 2010 and provided more than one-quarter of all new electric-generating capacity. Also, California, despite its fiscal problems, will require one-third of the state’s electricity to come from renewable sources by 2020.
But those are the bright spots. Some dark ones include the following:
• The Wisconsin State Legislature is considering a bill that would restrict the development of approximately $500 million worth of projects over the next two years. According to the Milwaukee Journal Sentinel, Republican Gov. Scott Walker says wind costs too much and impedes on rural property rights. The legislature voted in March to suspend wind farm siting rules. The five-to-two vote tracked along party lines, with all five votes to suspend coming from Republican members;
• Texas comptroller, Republican Susan Combs, has decried wind as an expensive boondoggle that does not produce jobs. The state’s GOP-controlled legislature may limit the ability of local school districts to give tax abatements, which wind advocates in the state say will limit development in rural areas; and
• The 2012 extension of the production tax credit could be in jeopardy, given the budgetary concerns on Capitol Hill. Jon Chase, vice president of government relations for Vestas-American Wind Technology, told an AWEA finance and budget workshop in April, “All the credits out there are going to be looked at very closely. Everything is going to be on the table.”
“There are politicians who can make political hay by playing to that constituency,” says Tom Konrad, who manages several green energy stock portfolios and is editor of AltEnergyStocks.com.
As part of this political footwork, Konrad says rhetoric debunking climate change has increased markedly over the past several years, more or less in relation to how many Americans believe that climate change actually exists. If fewer Americans believe in climate change, fewer Americans will support wind and other renewables, he says.
This goes a long way toward explaining the difference in the current political and media attitude toward wind compared to just a couple of years ago. Also important, say wind industry analysts, has been the length and depth of the recession, both in how it has slowed development and made consumers more wary of higher energy prIces.
Whether or not some of these concerns may be warranted, says Tynion, the wind business should not discount the change in the political climate.
“Politicians and state regulators are withdrawing their support for wind across the board,” he says, citing the Wisconsin controversy as a prime example.
Walker’s proposed legislation would overturn a siting compromise three years in the making, says Tynion, adding that the compromise seemed to satisfy everyone involved: developers, rural landowners and regulators.
For its part, AWEA does not support the claim that wind energy is a wedge issue for either political party. “The fact is nine out of 10 voters Republicans, Democrats and Independents – want more wind power, as we found in a recent poll,” says Elizabeth Salerno, AWEXs director of data and analysis. “Specific to Republicans, AWEA found that 84 percent of Republicans believe increasing the amount of energy the nation gets from wind is a good idea.”
Has the backlash irreparably damaged wind? Has the momentum and goodwill built up over the past 20 years been lost? The answer is complicated and depends not only on what happens during the 2012 presidential and congressional elections, but on what the wind industry does over the next several years to regain lost momentum.
“There is still a great deal of support for wind and other renewables, both among Democrats and Republicans,” says Lowman. “And there are plenty of initiatives going on, especially on the East Coast. For example, Virginia Governor Robert F. McDonnell, a Republican, wants to build offshore wind.”
Education also remains key, say several analysts. Focusing on the longterm benefits of wind is important. If the green argument fails to work, there is always the economic one.
Lowman says there is reason to expect that renewable prices will continue to become more competitive with fossil fuels over the next decade.
Anne Mudge, an attorney at San Francisco-based Cox Castle & Nicholson, recommends that wind energy advocates should not let opponents dominate the discussion by focusing on the short term.
“Continue to demonstrate what is the truth – that there are economic benefits to wind, that it brings jobs, that it increases the property tax base and that it doesn’t take much in the way of government services,” she says.
In other words, do what wind has always done – but do it in an even more urgent way. Because, says Konrad, if the argument focuses on the short term, and if wind’s opponents can direct the discussion, “wind will remain a whipping horse.”
Click on the image above to hear a realtor talk about property values and wind turbines.