Wind Turbine Noise. ETSU-R-97 and emerging guidance on Wind Farm Developments

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1 Wind Turbine Noise ETSU-R-97 and emerging guidance on Wind Farm Developments By Diarmuid Keaney MSc. in Applied Acoustics, MIOA ICAN Acoustics Contact: Rev:6

2 Brief Introduction Diarmuid Keaney Company: ICAN Acoustics M.Sc. in Applied Acoustics (University of Derby) Diploma in Acoustics and Noise Control (University of Ulster) B.E. from NUI.

3 Overview of today s talk... A brief review of ETSU-R-97 Emerging guidance A GOOD PRACTICE GUIDE TO THE APPLICATION OF ETSU-R-97 FOR WIND TURBINE NOISE ASSESSMENT

4 EN

5 Typical Wind Turbine Sound Power Levels Sound power levels from a wind turbine typically vary with the speed of a wind turbine (higher wind=greater sound power level, lower wind=lower sound power levels) At 4m/sec (ref height of 10m) the sound power level could be At 9m/sec (ref height of10m) the sound power level could be 95dB(A) 104dB(A) Note: Wind speeds can vary across a site, hence wind turbines can emit different noise levels across the same site.

6 A wind turbines Sound Power Level is frequently reported at a 10m reference height (good data) Hub Height Hub Height Hub Height Hub Height Hub Height Wind speed (ref 10m high) 80m 90m 100m 110m 130m 5m/sec 6m/sec 7m/sec 8m/sec 9m/sec 10m/sec 96dB(A) 97dB(A) 99dB(A) 102dB(A) 104dB(A) 99dB(A) 99dB(A) 100dB(A) 99dB(A) 99dB(A) 102dB(A) 102dB(A) 102dB(A) 102dB(A) 102dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 104dB(A) 107dB(A) 107dB(A) 107dB(A) 107dB(A) 107dB(A)

Older turbines generally had more mechanical noise Note: It is a common misconception Note: It is a

7 So how do wind turbines make noise? What makes noise? For modern wind turbines this is mainly aerodynamic noise. Older turbines generally had more mechanical noise Note: It is a common misconception Note: It is a common misconception that modern turbines do not generate tonal noise, however this is not the case. Measurement data frequently shows elevated tonal elements at certain speeds or modes of operation.

8 Generate noise from 20Hz to 3600hz Varies with: -wind speed -blade pitch -blade speed Source: Wind Turbine Noise Warner,Bareiß & Guidati

9 ETSU-R-97 ETSU-R-97 : Prepared by a working group in September 1996 for the Department of Trade and Industry in the UK (now 17 years old) ETSU Energy Technology Support Unit Working Group: Acoustic Consultants,County Councils, District Councils, Solicitors, Power Companies. BTW: The DoEHLG Guidelines issue in 2006, some 10 years after ETSU-R-97.

10 How a baseline noise survey is conducted Source: IoA Good Practice Guidelines Draft

11 At a noise sensitive receptor Wind speed on the site Met Mast measures at two heights to determine the wind speed at a reference height of 10m

12 The Baseline Study combined with Met Mast info

13 BACK to our Baseline Study data...

14 LA90 =35~40dB (Daytime) or 5dB(A) above background

15 LA90 =43dB (Night) or 5dB(A) above background

16 What an ETSU-R-97 assessment should include as a minimum A noise impact assessment for a wind farm should include: 1. A baseline noise study to examine the existing noise climate at ALL operational speeds for the proposed wind turbines (5m/sec, 6m/sec, 7m/sec.) 2. The selection of a suitable wind turbine using quality noise data that is guaranteed by the manufacturer (via an independent test house). 3. The manufacturer should issue a guaranteed sound power level. 4. The building of a 3-D noise contour model using GIS data and the turbine data modelled at the planned heights. 5. A noise assessment of the noise impact created at all noise sensitive locations within the immediate vicinity.

17 Our own findings in relation to critically reviewed wind farm proposals and the application of the data in Ireland. Noise impact assessments where the promoter or EIS author has not even conducted a baseline study. The use of turbine noise data which clearly states in the small print that it should not be used for prediction purposes and that it does not form any part of a guarantee. Opening paragraphs where the author of the EIS claims the use of best practice guidance such as ETSU-R-97 and yet the author uses the less onerous DoEHLG limiting values of 45dB which suits his/her assessment (usually in favour of the applicant) Attempted assessments where the assessment method is not understood by the author and in some cases the person who has conducted the assessment has formal qualification in acoustics.

18 More of our own findings Octave band data is not used in the prediction process, so absorption effects due to air is not considered. Poor modelling using generic wind farm packages where there is a bolt-on Noise Module. Most of these modules are over simplified and can be in highly accurate and limited. Predictions that are conducted at a single wind speed using a concept called Critical Wind Speed which is not in accordance with ETSU guidance. Higher noise levels at houses justified on the ground that those in the dwellings have a financial interest in the wind farm. ETSU states a higher limiting value of 45dB is appropriate for these houses.

19 Emerging Guidance (UK) "Good Practice Guidance to the application of ETSU-R- 97 for wind turbine noise assessment". On 18/12/2012: The Institute of Acoustics has published the responses to its consultation on "Good Practice Guidance to the application of ETSU-R-97 for wind turbine noise assessment". On 21/05/2013 (NEXT TUESDAY): The IoA will launch the A GOOD PRACTICE GUIDE TO THE APPLICATION OF ETSU-R-97 FOR WIND TURBINE NOISE ASSESSMENT NOTE: This is an addition to the 17 year old ETSU-R-97 Document

20 Emerging Guidance (Ireland) Wind Energy Guidelines: Review of noise and shadow flicker standards Submission deadline: 15 th Feb 2013 Our company made a submission (early Feb 2013) as did the Irish Branch of the Institute of Acoustics. We understand that there were 550 submissions. We await formal and official confirmation of receipt of our submission as of the 17 th of May SEAI recently issued a tender request to desk study of peer reviewed studies and guidance un other countries.

21 The IoA Good Practice Guidelines will most certainly address this issue. Source: IoA Good Practice Guidelines Draft

22 Other guidance and papers Number of papers in circulation about specific topics such as the effects of Low Frequency Noise (LFN), Infra Sound or Amplitude Modulation (AM): To assist with study credibility always check: The qualifications of the author and ascertain if they are suitably qualified in this specific area? Who are the authors and what was each authors contribution to the study? Has the author(s) any potential bias (is this truly an independent study?) Who the paper has been commissioned by and why (this should be disclosed)? Establish if the paper has been peer-reviewed by qualified peers. If the paper has been published by any Journal and if not, why not? ( for example Journal of Applied Acoustics). Is the paper is conclusive in its findings? (watch out for more research needed)

23 Thank you for your time. Contact Details Diarmuid Keaney LinkedIn (search): Diarmuid Keaney ICAN Acoustics Web: Tel: and Low Call National: N.I

The acquisition of baseline noise data at receptor locations, and the analysis of this data, to take account of site-specific wind shear.

The acquisition of baseline noise data at receptor locations, and the analysis of this data, to take account of site-specific wind shear. Prediction and Assessment of Wind Turbine Noise 1 Introduction 1.1 There are continuing disputes about the factors to be taken into account when assessing noise from wind turbines, and the weight to be