While it’s increasingly acknowledged that turbines will be audible much of the time, complaints about noise are too often painted as being unworthy of serious consideration, either because turbines are not all that loud, or because of an insistence that noise complaints are bogus surrogates for a broader opposition to wind energy that is “really” based on visual impacts or economic arguments (driven in some cases by climate change denial).

Perhaps most crucially, wind advocates rarely acknowledge that turbine noise is often 10 dB louder than background sound levels (sometimes even 20 dB or more); acousticians have long known that any increase over 5 dB begins to trigger complaints, with 10dB the threshold for widespread problems.

Meanwhile, many community groups are over-reaching in their approach to reducing noise impacts, by focusing too much of their argument on possible health impacts of wind turbine noise exposure. While there are many reliable anecdotal examples of people having physical reactions to nearby turbines, even the accumulating number of reports of health reactions to new turbines represents a small minority of people who live within a mile or even half-mile of turbines. 

The health claims are hard – and perhaps impossible – to prove, though some insist that any health impact is unacceptable.  Much more telling are community response rates that affirm – in some types of rural communities – that 25-50 percent of people hearing turbines near the regulatory sound limits feel that their quality of life is severely impacted.

AEI’s new report, Wind Farm Noise 2011, aims to frame the current state of research and policy in a way that can help those trying to find a constructive middle ground that protects rural residents from an intrusive new 24/7 noise source while also encouraging wind development as part of our renewable energy future. 

A series of court and environmental tribunal rulings in recent months shed an especially illuminating light on the ambiguous state of our current understanding of wind farm noise impacts.  In each case, the ruling rejected some elements of the challenge while affirming the validity of other claimed impacts or stressing the need for continued investigation. 

In Australia, a planned wind farm was derailed by an environmental tribunal responding to an appeal from a local farmer who had focused on the possible noise impacts on his family and his livestock.  The tribunal rejected evidence related to health effects from noise, but held that the planned layout would impact the “visual amenity” of the area to an unacceptable degree (in Australia and New Zealand, “rural amenity” is a commonly-accepted planning and regulatory consideration).  In this case, the tribunal ruled that siting turbines 1km (0.6 miles) from homes, with some homes surrounded by several turbines within 2km (a mile and a quarter), was too close.

In Minnesota, the Public Utilities Commission rejected a half-mile county setback, but required the developer to offer financial compensation to 200 residents within a half-mile, though outside the regulatory limit of 1630 feet.

In Ontario, a major challenge to the Province’s new Green Energy Act was denied, and the 223-page ruling offers a great primer on current research from all sides.  The challenge was based on the health impacts argument, and failed on that count, but the tribunal stressed that “risks and uncertainties” remain.  While the evidence to date was determined to be “exploratory” rather than “confirmatory,” continued study was urged. The report noted: “The Tribunal accepts that indirect effects are a complex matter and that there is no reason to ignore serious effects that have a psychological component.”

Finally, and perhaps most strikingly, in the UK an appeal of a planned wind farm (based on the claim that the regulations were insufficient) was denied, but the High Court affirmed the validity of an amplitude modulation (AM) condition in the regulations, which is very stringent: whenever sound levels are over 28 dB, AM cannot exceed 3 dB. After years of denying that AM is an issue in UK wind farms, the industry there faces a starkly restrictive standard that would, in effect, preclude wind farm operations when any blade swish is audible, even in distant, barely audible turbines.  Renewable UK (formerly BWEA) is scrambling to fund research that can be used to better quantify AM so that new rules providing a reliable dB penalty for AM can be devised.

My experiences around wind farms in Texas, Wisconsin, Nebraska, Kansas, and Wyoming has been very consistent: I have always been able to clearly hear any turbines that were within a half mile (faintly, but clearly there); at a quarter to third of a mile, the sound stood out, and as I approached three-quarters of a mile, the sound faded into the background sounds of distant roads or ground breeze.  These have been brief experiences, always in daytime with moderate wind.

Adding to these personal observations, the widespread reports of neighbors affected by unexpectedly intrusive levels of noise from turbines up to a half mile or so away as well as ranch-country experience that suggests noise levels of 45-50 dB are often easily accepted, lead to my current perspective that the most constructive and widely beneficial path forward would be a shift toward larger setback requirements (in effect, lowering the maximum noise levels at homes nearly to quiet night time ambient noise levels), combined with easily crafted easement provisions that allow turbines to be built closer to landowners who agree to allow it. 

This approach, currently used in Oregon, would protect communities and individuals who have invested their life savings in a quiet rural lifestyle, while acknowledging that there are many people in rural areas who are ready and willing to support wind energy development, even near their homes.

Yes, some locations – in fact many locations with relatively small lot sizes – may be hard or impossible to build in, but these are exactly the locations where the social tradeoffs, and the resulting balancing of costs and benefits, are least clearly favorable to wind development anyway.  If the industry can accept that it doesn’t have the right to build anywhere the noise can be kept to 50 dB, and that its future development will be taking place within the fabric of a diverse society, then there is a clear business opportunity emerging for those companies that take the lead by crafting truly responsive community relations programs.  

These companies will commit to working with the standards set by local tolerance for new noise sources, rather than pushing local or state authorities to adopt siting standards used elsewhere.  These leading edge wind companies may also put their money where their mouth is on property values by establishing programs that compensate landowners for moderate changes in property value (which are likely to be less common than feared), and helping create programs that buy and sell homes, so residents who wish move can do so quickly at fair market value.

These companies will develop reputations as developers that are ready to be good local citizens, and will find that the increases in some costs and a willingness to forsake some locations altogether leads to dramatic benefits in terms of long-term stability and acceptance in the communities where they work – and especially in communities where they propose new projects.

Noise concerns are not obstacles to wind development, if the industry and local and state regulators can move beyond simplistic denial of the problem. Indeed, the continued growth of the wind industry in the U.S. and Canada may depend upon a fundamental shift of attitude, centered on respecting communities that choose lower noise limits, and providing assurances that negative impacts will be addressed if they occur.