Q. Is curtailment a viable strategy to reduce power and sound for wind turbines?
A. Curtailment can be done on a limited, turbine-by-turbine basis for a variety of reasons such as reducing power during low demand periods, performing maintenance on the turbine, and responding to high wind events. Power reduction occurs by simply reducing the speed of the rotor through feathering the blades and spilling wind - much like a sailboat reduces speed by adjusting sails. Reducing rotor speed will tend to reduce sound levels, but there is no guarantee. Under some conditions, feathering the rotors to reduce rotor speed may actually increase sound levels.
Q. To your knowledge has a wind farm ever been designed with a curtailment strategy in the United States?
A. No. Wind turbines and wind farms are designed to operate at maximum capacity. It makes little sense to invest in larger turbines and then reduce power output to comply with noise limit regulations. The solution to Highland's design flaws is to use smaller turbines, which would allow the turbines to operate at full power as they were designed, and comply with all applicable noise regulations. Relying on untested software to predict when noise limits are being exceeded for a particular residence within a large wind farm, and expecting that the software will successfully reduce noise levels to maximum limits for each affected residence, is ludicrous.
Q. In your opinion, is Highland's curtailment mitigation strategy in the public interest?
A. No, absolutely not. To permit this wind farm with mitigation as the principal means of protecting the public would not be in the public interest. The solution is to build the wind farm with smaller, quieter turbines that will run at maximum capacity without requiring curtailment. Highland is proposing a grand experiment with the Town residents as the guinea pigs. The proposed turbines are too big and emit too much noise energy. In the wake of the severe health impacts experienced by some residents in the Town of Glenmore, which has similarly large turbines, it is troubling that Highland refuses to consider a full redesign of this project.
Q. Do you believe that Mr. Hankard's suggestion of using curtailment as a strategy to bring Highland into conformance PSC 128 noise limits is in the public interest?
A. In my opinion, no. The current proposal simply tries to squeeze a square peg into a round hole. As I have testified previously, the wind turbines suggested in this proceeding are simply too large for the layout of the Project, producing too much noise.
Q. Is the proposed mitigation plan workable?
A. Anything is possible, but the real question here is whether it is worth the long-term risk to area residents - who will have to live with this experiment for the next 30 years. Since there will be no real time noise data collected at each residence as the experiment unfolds, the burden will shift to the residents to prove that the noise limits are being exceeded. The problem is that the turbines proposed by Highland are too big, and their acoustic emission levels are too high, to meet current PSC regulations. Highland proposes a complex solution to a problem with a simple solution: the use of smaller turbines that produce less noise and require no curtailment.
Q. Are you still concerned about the health impacts of large mega turbines such as those proposed in the Town of Forest?
A. Yes. There is significant evidence from all over the world that large turbines placed too close to residences cause very serious health problems. While the research is underway, there is continuing focus on balancing the size and output of wind turbines with public health. I do not believe that the right balance has yet been struck. The wind industry continues to claim that there is no known link between wind turbine noise and health effects.
In a recent paper, which is being submitted as Ex.-Forest-Schomer-20, I show that for a small group of specially selected people, the probability that motion sickness-like symptoms experienced by wind farm residents are unrelated to wind turbine noise is less than two in a million. This analysis proves that it is virtually certain that these individuals are adversely affected with serious health effects that result from the acoustic emission of nearby wind turbines. This changes the dynamic of the situation. Since it can no longer be said that there are no known health effects related to wind farms, it follows that the industry must prove that there will be no adverse health effects from what they plan to do, or that the industry must state what the adverse health effects will be.
Q. Mr. Hankard treats the inputs to and predictions from ISO 9613-2 as absolute maximum noise levels. Is this the case?
A. No, it is not the case. I have closely examined the data presented in Ex.-HWF-13 Hessler-3 (PSC Ref. # 172233) in this matter, which attempted to measure the accuracy of noise level predictions made by using ISO 9613-2. The Hessler data show that turbine noise tends to be louder at night. These data result from two weeks of continuous measurements at 1000 feet in three directions (north, south and east) from the east end of an east-west line of wind turbines in 10-minute intervals. Averaging the daytime data (7 AM to 10 PM) reveals values of 31, 30, and 30 dB for the three directions. During the night (11 PM to 5AM) the average 20 noise levels increase by 6 dB to 37, 37, and 36 dB from the same three locations. This same "nighttime" effect is likely to occur in the Town of Forest. Although data collection of turbine noise levels during various times of the year would likely produce different average sound levels, the important point is that there is a significant increase in noise levels at night which is between 3 and 6 dB.
Q. How does this relate to the requirement that nighttime levels not exceed 45 dBA?
A. What this means is that it would be misleading to use a 24 hour noise prediction for a wind farm to calculate the nighttime levels. The 24 hour prediction averages lower daytime levels with higher sound levels at night. The reality is that the night-only levels will be on the order of 3 dB louder than the 24 hour prediction.
Q. Are bigger wind turbines better for people?
A. The history of wind turbines, as young as they are, is one of ever increasing size. Current units go from 1.5 to 3.5 MW, and bigger units can be expected in the future. Larger turbines may have the advantages of greater efficiency and net profit but they create more problems for people living close by. There is strong evidence that the very low infrasound frequencies produced by large wind turbines are the sources of acoustic emission that are adversely affecting people. As the power generated by wind turbines grows, the blades grow and hence the tip's speed is reduced to avoid too high an advancing blade tip Mach number.
According to a paper by van den Berg (2004), which is being submitted as Ex.-Forest-Schomer-22, the increase due to a typical nighttime wind profile (the change in velocity with altitude) was 5 dB for a wind turbine with a 58 m hub height, and up to 15 dB for a turbine with a 98 m hub height. That is, the increase in low frequency energies in size and magnitude may be substantial because of this blade-loading, wind-gradient effect, much greater than what is predicted for constant blade loading. The conclusion is that unless mitigation methods and strategies can be developed and implemented, bigger turbines are not necessarily better. They may actually be much worse for people.