Ontario engineer William Palmer has proposed a rigorous, but simple and transparent technique to assess wind turbine noise, that could replace the problematic complex computer models and “black box” algorithms currently used in the Ontario Ministry of the Environment and Climate Change newest protocol to assess wind turbine noise compliance.
Speaking at the International Conference on Wind Turbine Noise that took place in Rotterdam beginning May 2, Palmer said of his proposed method,
The method had to consider that an effective monitoring system must take into account more than just averaging sound power levels over a long term. The method recognizes that humans are bothered by the changes and annoying characteristics that occur, as well as long term averages. Others describe this as the need to determine how the special characteristics of sound quality may impact quality of life.
To verify this approach, assessments were conducted using the method at two wind power developments in Ontario. In the K2 Wind project, he used MOECC data from testing in early March 2017 at a home within the K2 project. He was able to demonstrate that the MOECC data confirmed that the noise from the turbines surrounding the home had a tonal quality; that means it should require a 5 dB(A) penalty be applied to the other test results.
Although the Ministry did not provide calibration files for their sound recordings they did provide in their report their assessment of the sound pressure level for each sample. Using the Electroacoustics Toolbox, and working backwards to set the given sound pressure level for a number of the recordings provided as the calibration level, permitted a “Quasi Calibration” of the Ministry data, and from that a calibrated FFT analysis was made. … Again, it was seen that when the residents described adverse effects in their comments filed with their initiation of recordings, FFT analysis of the sound recordings taken at those times clearly show a tonal condition occurring at about 450 Hz.
In the Enbridge project, where Mr. Palmer also conducted testing, he found similar tonal quality to the noise emissions in that project, and confirmed that the noise coming from the turbines is above the approved levels at several locations.
For this facility as an example, where the turbines first went into operation in November 2008, and citizen complaints occurred soon after, it has not yet been possible to complete a report to demonstrate compliance. The monitoring is still in progress, over 8 years later, with the turbines continuing in operation, and residents continuing to complain. The hypothesis is that individual samples are not representative due to variation.
Process is complex
He offered comment on the current protocol being used to assess compliance by the MOECC:
A premise of the Ministry of the Environment and Climate Change wind turbine monitoring protocol is that monitoring to show compliance must be conducted over a long period. The protocol requires the initial acoustic monitoring by residents to produce at least a 10-minute sample for each complaint period, and the final compliance protocol requires a minimum of 120 one-minute measurement intervals for each integer of wind speed. During each of those one-minute intervals there must be no changes in wind speed or direction. A further 60 samples are required for each integer wind speed with the turbines not operational. So far data collection has taken years to obtain a sufficient number of samples, and in at least one array, initial reports showed that over 90% of samples taken were discarded as non-compliant. All samples are logarithmically combined to determine the Leq produced by the facility, which eliminates any short-term change effects. This appears to be precisely the sort of monitoring that was cautioned against by Genuit and Fiebig described in Section 1 when they noted, “By relying on sound pressure levels averaged over long time periods and suppressing all aspects of quality, the specific properties of environmental noise situations cannot be identified, because annoyance caused by environmental noise has a broader linkage with various acoustical properties such as frequency spectrum, duration, impulsive, tonal and low-frequency components, etc. than only with SPL [Sound Pressure Level]. In many cases these acoustical properties affect the quality of life.”
The annoyance aspects that impact the quality of life of impacted residents are not being assessed.
People walking away from loved homes
The current protocol cannot possibly identify critical issues in wind turbine noise emissions, Palmer asserts. In conclusion, he said:
This paper has demonstrated a method for rigorous monitoring of wind turbine sound. The goal of the method was to establish evidence for the condition noted by Karl D. Kryter: “The most direct, and perhaps most valid, insight into the possible presence and magnitude of stress reactions in general living environments is probably that which has been obtained from attitude surveys and real-life behaviour of people.” Behaviours such as walking away from an unsold loved home to live at the home of a family member, or when normal people become activists in trying to communicate their concerns provide such valid insights. The rigorous method had to consider the present acceptance criterion for wind turbines, in light of the insight given by those who study the quality of noise and its relation to annoyance. Those who study the subject identify that, “Current acceptance criterion relying on sound pressure levels averaged over long time periods and suppressing all aspects of quality cannot identify the specific properties of environmental noise situations.”
The results reported by Bill Palmer are typical of the community testing being undertaken in many communities near wind turbine projects across Ontario.
These findings indicate that the complex processes used by the MOECC and required of wind companies for compliance testing fail to identify key issues that can be quickly identified using much simpler techniques.
Meanwhile, the turbines, shown by other methods to be out of compliance, continue to operate.
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