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Wind turbines; Distance is not the culprit nor the remedy for health issues  

Credit:  Posted By: Dan Reid, Owen Sound | Posted On: February 12, 2013 | lfpress.com ~~

Imagine your home in a quiet rural setting with no neighbours for miles around. At the back of the house is a panoramic window with a view of the countryside. Parallel to that back wall exactly 1km away is a fence row of 5 industrial wind turbines. The turbines are arranged like fence posts 400 metres apart to avoid operational difficulties. Each turbine is rated at a 102 db(A) noise level and the turbine in the middle of the group lines up perfectly with the centre of your panoramic window.

Now let’s advance this entire fence row of 5 turbines progressively closer to the house, up to the point where the cumulative noise of the entire group creates 40 db(A) of noise at the house. At that point, the two turbines on either end of the fence row would be 974m from the house. Moving towards the middle of the fence from both ends the next two turbines would be 684m away. The final turbine in the centre of the fence, aligned with the panoramic window, would be 550m from the house. This is how the 550m setback became a reality.

This distance was not plucked as a magic number from some scientific journal, nor was it arbitrarily picked out of the air. It is the direct by-product of the MOE regulation of a 40 db(A) compliance limit for noise at homes exposed to industrial wind turbines.

If we were to eliminate four of the five turbines and leave the middle turbine at 550m from the house, the predicted noise level at the house would decrease by almost 5 db(A). That change in magnitude could be the difference between health and ongoing disability from noise annoyance. Close proximity to a turbine is not the culprit.

On the other hand, if we removed the turbine at 550m and left the other four in place, thereby increasing the distance to the closest turbines to 684m, the cumulative noise level at the house would only drop by about 2 db(A). That difference in noise volume is barely detectable. Arbitrarily increasing distances to turbines is therefore not a remedy.

Obviously, if we were to increase the size of this fence row with more turbines or increase the sound power level of each above 102 db(A), or both, we would increase the level of noise at the home. As a result, the entire fence row would be moved back to meet the 40 db(A) compliance limit. You would expect therefore as wind projects grow in size with more powerful noisier turbines, that the 550m setback would be rare. In fact, this is precisely what happens. If you were to take a look at any number of wind projects such as Zephyr, Gesner, Conestoga or McLeans Mountain which totally involve dozens of turbines and literally hundreds of non-participating receptors, you would not find one example of a turbine located at 550m from a receptor. The closest turbine to any receptors in these projects varies from just over 600m to 800m away. In my opinion, distance as an issue and 550m in particular, gets more attention than it deserves.

In contrast, the issue that never gets any appropriate level of attention is the cumulative nature of noise predictions. Under the current GEA rules the predicted noise level at any receptor is an aggregate of the noise from the closest turbine plus every other turbine within a 5km distance. The resulting predicted noise level is dependent on the number of turbines clustered in that distance and the sound power level of each turbine.

Due to this aggregate approach, in every proposed industrial wind project under the GEA you will find examples of; a) receptors which are closest to turbines do not have the highest predicted noise levels; b) different receptors whose closest turbine is exactly the same distance away with significantly different noise levels and; c) different receptors whose closest turbines are drastically different distances away with nearly identical predicted noise levels.

A current topical illustration of this is the Cedar Point Wind Project being developed by Suncor. That proposal is for 46 Siemens turbines whose power levels range from 2- 2.3MW which will impact 893 non-participating receptors. Noise predictions unfortunately have not been made public for the receptors located 1500m or more from their closest turbine. However, available data for receptors inside that distance is informative. There are 474 receptors closer than 1500m to their nearest turbine which represents more than half of all impacted receptors.

To highlight how aggregate noise predictions distort the linear relationship between distance and noise consider the following from Cedar Point. There are a dozen different receptors located between 1000m and 1010m from their closest turbine. Noise predictions for this group vary by more than 5 db(A) from 32.6 db(A) to 37.7 db(A). Similarly, the median predicted noise level for all receptors inside 1500m is between 33 db(A) and 34db(A). There are 74 receptors within this single decibel range but the distance to the closest turbine across all these receptors varies by well over half a kilometer, from 804m to 1494m. Suffice to say, that if distance is the key to protecting health which one would be the choice from all these permutations?

Cedar Point is topical because the Mayor of Plympton-Wyoming has committed to enforce a newly created by-law for a 2km minimum setback. This 2km setback figure has gained notoriety as it has been recommended in other parts of the globe. However, the substantiation for why this distance is key, has not been well articulated.

Suncor has been awarded a 100MW FIT contract for Cedar Point. A 2km minimum setback opens the door for Suncor to upgrade their current proposal. Hypothetically, rather than 46 2-2.3MW turbines they could use 33 – 3MW turbines to fulfill their contractual agreement. Admittedly, the entire footprint of the project could be downsized and as a result, somewhat less than 893 receptors may be affected. But it is more than feasible that for those who remain impacted, the larger and noisier 3MW turbines could result in increased predicted noise or at least similar levels to those in the initial configuration, even at a 2km setback distance. By acting only on distance without regard to allowable noise limits, the end result may offer no increased protection against ill-health.

Alternatively, if action was focussed on noise limits that were more aligned to the reality of rural settings, health issues could be minimized. Using our 5 turbine fence row scenario, if the current target of 40 db(A) at any receptor was revised to 25 – 30 db(A) as an example, our entire fence row of 5 turbines would be pushed back. This reduced noise limit would not change the convoluted array of distance relationships between homes and turbines we see in every project, but it would move the chaos further away and it would be done for the right reason, not arbitrary choices. How far away is undetermined but distance is a secondary consideration. It’s the noise level we are trying to deal with.

Systematically destroying the health and well being of citizens is the problem. Exposure to intrusive environmental noise is the culprit. An educated reduction of current allowable noise limits is the remedy. Haphazardly experimenting with distance limitations doesn’t put us on the road to success, it means we took the wrong turn.

Source:  Posted By: Dan Reid, Owen Sound | Posted On: February 12, 2013 | lfpress.com

This article is the work of the source indicated. Any opinions expressed in it are not necessarily those of National Wind Watch.

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