PRESENTATIONON WIND TURBINE AM

• by Geoffrey Weller BSc CEng FIET

Introduction

• ETSU-R-97 (ETSU) is failing to protect neighbours from Amplitude Modulation

• ETSU is used to assess noise in planning applications. Embedded into government policy

• Additional protection for AM is needed because AM may exceed maximum level quoted in ETSU

• I will summarise my Proof of Evidence, add recent events, amplify previous conclusions

What is AM?

• To demonstrate the character of AM, I would like to play two audio files.

Source: Dick Bowdler FIOA Noise Consultant

Source: Recordings of Nature website

• There are actually two separate recordings in this file.

Proof of Evidence

• The DTI commissioned the 2006 Hayes McKenzie Partnership report:

The Measurement of Low Frequency Noise at Three UK Wind Farms

Recent and Forthcoming Papers

• From 5th International Conference on Wind Turbine Noise Denver 28-30 August 2013

• Audible amplitude modulation - results of field measurements and investigations compared to psychoacoustical assessment and theoretical research

• Mike Stigwood, Sarah Large and Duncan Stigwood, MAS Environmental Ltd, UK

  Wind Farm Location MW per turbine

No. of turbines

Hub Height (m)

Reference

1 Aggregate Ind Newquay Cornwall 0.5MW 1 59 Audio examined

2 Alltwalis Carmarthenshire 2.3MW 10 65 Statement from complainant - clear case

3 Askham Cumbria 660kW 7 40 Salford - clear case added

4 Site B Banff and Buchan ANON Confirmed AM by resident - anonymous at moment

5 Bears Down Cornwall 600kW 16 30 Salford - clear case added

6 Bicker Fen Lincolnshire 2MW 13 59 Statement from complainant - clear case

7 Black Law, Forth South Lanarkshire 2.3MW 42 82 Reported by others

8 Blaen Bowi Carmarthenshire 1.3MW 3 46 Salford - clear case but not added

9 Carland Cross Cornwall 400kw 15 30 In ETSU-R-97 and Salford - now repowering

10 Cairnmore Aberdeenshire 850kW 3 55 Information on complaints is second hand

11 Causeymire Highland 2.3MW 21 60 In Salford but not added by Salford

12 Coal Clough Lancashire 400kw 24 30 In ETSU-R-97 missed in Salford

13 Cold Northcott Cornwall 300kw 22 25 In ETSU-R-97 - in Salford but not added by them

14 Coldham Cambridgeshire 1.75MW 8 60 Statements from complainant matches AM

15 Conisholme East Midlands 800kW 20 65 Evidence from others

16 Cotton Farm East Anglia 2MW 8 80 MAS have measured EAM

17 Cruach Mhor Argyll & Bute 850kw 35 45 Salford - but not added

18 Crystal Rig Scottish Borders 2.3MW 51 + 9 60 + 80 Evidence from others

19 Dalswinton Dumfries 2MW 15 80 Confirmed by the LA and affected resident

20 Darracott Devon 850kW 3 50 Complaints by residents of AM clearly ID AM

21 Deeping St Nicholas Lincolnshire 2MW 8 59 In Salford and added, MAS confirmed

22 Delabole Cornwall 2.3MW 4 99 (tip) Direct complaints and advice of acoustician

23 Forestmoor, Bradworthy Devon 1MW 3 48 Evidence of others

24 Four Burrows Cornwall 300kW 15 30 In Salford - 'another' noise complained of

25 Fullabrook Devon 3MW 22 65 Complaints by many residents of AM, post Salford

26 Gedney Marsh (Red House) Lincolnshire 2MW 6 59 Indirect evidence

27 Glens of Foundland Aberdeenshire 1.3MW 20 46 In Salford but not added

28 Glyndebourne Lewes District 850kW 1 44 Independent source - see also article in Private Eye No.1334

29 Hadyard Hill South Ayrshire 2.5MW 52 60-70 In Salford, possible case, but no direct evidence

30 Hafoty Ucha Gwynedd 850kW 1 39-44 In Salford, questionable case, but no direct evidence

31 Harlock Hill Cumbria 500kW 5 35 In Salford, but no direct evidence

32 Hazlehead Yorkshire 2MW 3 60 Indirect complaints from residents - monitoring by developer being undertaken

  Wind Farm Location MW per turbine

No. of turbines

Hub Height (m) Reference

33 High Volts County Durham 2750kW 3 60 Indirect evidence

34 Hill of Easterton Aberdeenshire 850kW 3 45 Indirect evidence / information

35 Kessingland Suffolk 2.05MW 2 80 Complaints and MAS measured, post Salford

36 Knabs Ridge North Yorkshire 2MW 8 58 Complaints and MAS measured - post Salford

37 Lissett Yorkshire 2.5MW 12 80 Controls introduced to reduce noise

38 Llandinam P&L Wales 0.3MW 103 31 In ETSU-R-97

39 Llangwryfon Ceredigion 0.85MW 11 40 Indirect information - complaints from residents

40 Llyn Alaw Anglesey 600kW 34 31 In Salford and WAS added

41 Lynch Knoll Gloucestershire 500kW 1 42 In Salford but not added

42 Lynemouth Northumberland 2MW 13 78 Indirect evidence / information

43 Mablethorpe Lincolnshire 600kW 2 65 Indirect evidence

44 Michelin Tyre Factory Dundee City 2MW 2 85 In Salford but not added

45 Moel Maelogen North Wales 1.3MW 9 50 Indirect information, in Salford but not added

46 Mynydd Clogau Powys 850kW 17 34 In Salford, possible case, but no direct evidence

47 Mynydd Gorddu Ceredigion 0.5-0.6MW 19 34-35m Indirect information

48 Newstead Cuminstown 0.8MW 1 49 Multiple sources of evidence from residents

49 North Pickenham Norfolk 1.8MW 8 80 MAS measured - residents not complaining officially

50 North Rhins Dumfries 2MW 11 60 Indirect information

51 Parc Cynog Carmarthenshire 720-850kW 5+6 60 When extended in size

52 Penrhyddlan & Llidiatywaun Powys 300kW 103 45 Noise problems noted in ETSU-R-97

53 Red Tile / Warboys Cambridgeshire 2MW 12 59 MAS measured and complaints - missed by Salford

54 Rhyd y Groes Ceredigion 300kW 24 31 Noise problems noted in ETSU-R-97

55 Royd Moor South Yorkshire 500kW 13 35 In Salford but not added, MAS heard

56 Site P - single turbine Pembrokeshire ANON     Confirmed by EHO

57 Skelmonae Ellon, Aberdeenshire 0.8MW 4 64 Controls in place to reduce noise

58 South Sharpley Easington District 1.3MW 2 65 Evidence from affected residents

59 St Breock Cornwall 450kW 11 35 In Salford but not added

60 Swaffham Norfolk 1.8MW 1 67 Complaints and MAS measured, missed by Salford

61 Taff Ely South Wales 0.45MW 20 35 Indirect information

62 Tir Mostyn & Foel Goch Denbighshire 850kW 25 49 In Salford but not added

63 Trysglwyn Gwynedd 400kW 14 25 In Salford but not added

64 Wadlow Cambridgeshire 2MW 13 80 MAS have measured and confirmed with direct observations 

65 Walkway Wind Farm Sedgefield District 2MW 7 69 Evidence from affected resident clearly identifies AM

66 Wharrels Hill, Bothel Cumbria 1.3MW 8 76 Complaints by residents of AM, post Salford

67 Whittlesey Cambridgeshire 1.8MW 1 80 Turned off at night

Renewable UK Annual Conference Birmingham 5-7 November 2013

• Only 3 papers will be presented on technical issues (Session B8), all of them devoted to AM noise of Onshore Wind Turbines

• RenewableUK AM Research Project – Overview of Phase 1 Research Findings

• Affective Response to Amplitude Modulated Wind Turbine Sound

• Mechanisms and Causes of Amplitude Modulation (AM) and Other Amplitude Modulation (OAM) of Aeroacoustic Wind Turbine Noise

ETSU-R-97• ETSU explains level of AM assumed in noise limits:This modulation of blade noise may result in a variation

of the overall A-weighted noise level by as much as 3dB(A) (peak to trough) when measured close to a wind turbine. As distance from the wind turbine/wind farm increases, this depth of modulation would be expected to decrease as atmospheric absorption attenuates the high frequency energy radiated by the blade.

• The term ‘as much as’ indicates the maximum level of AM envisaged, and cannot be interpreted as a typical or indicative value. It is clear that lower levels were expected at increased distance, such as at a neighbouring property

Statutory Nuisance

• Without any national standards for AM, it is suggested that noise problems can use the Statutory Nuisance complaint procedure via the Local Authority

• To this effect, a 127-page report detailing a complete Wind Farm Noise Statutory Nuisance Complaint Methodology has been produced for DEFRA

AECOM Wind Farm Noise Complaint Methodology NANR 277 120 Appendix B: Wind Farm Complaint Investigation Flowcharts – Flow Chart 1: Overall Investigation

Statutory Nuisance

• Difficult, lengthy, risky and expensive process• Local Authority may not act, or may be

delayed by appeals. ‘Best practicable means’ defence often available

• Difficulty in proving noise nuisance –noise may last many nights, then disappear entirely for a while

Controls to avoid Statutory Nuisance Claims

• Foreseeable harm in allowing the level of AM to be uncontrolled

• Precautionary approach needed• AM Planning Condition would be win-win for

developer and neighbours

Conditions

• Den Brook planning conditions 20 and 21 regarding AM

• 3 dB limit for AM, the maximum value for AM specified in ETSU.

• ETSU has has no dose-response studies, so neither does the condition

• Would not inhibit properly-designed windfarms

Conditions

• The Den Brook planning condition was reviewed by Moroney and Constable:

The Den Brook condition is straightforward and that it is possible for this condition to be employed in a transparent and objective manner to demonstrate the existence of excess AM in wind turbine noise.

Challenge to the Den Brook Conditions

• RES challenged the Den Brook AM planning condition – their Dr Jeremy Bass reported background noise creates false positive indications of AM

• The Moroney and Constable report showed how false positives could easily be avoided by correlating data with Blade Passing Frequency

• MAS Environmental analysed the data used by Dr Bass, and showed false positives caused by common noise sources that would be recorded and disregarded - bird calls, aircraft and car alarms.

Conclusions• Each of the five windfarms involved in this

Conjoined Public Inquiry has more turbines than Den Brook, and these are all of similar height or taller than Den Brook.

• Taller and more numerous turbines leads to an increased risk of AM.

• AM is likely to be worse in areas of low background noise such as Mid Wales.

• Precautionary approach needed • In the absence of nationally specified controls for

AM the Den Brook AM test, or another test for AM agreed by the parties involved, should be a condition of development and operation.