PAGE 1Department 04/20/23

The Environmental Assessment of Wind Farms

John AinslieHead of Consents

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The Environmental Assessment of Wind Farms

What is a wind farm ?

What is the development process ?

The EIA Process

A Note on Noise Assessment

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Components of a Wind Farm Development

> Wind turbines – typically 125m to blade tip

> Foundations

> Anemometry mast

> Access tracks, crane hardstandings, access to the site

> Site substation / control bldg, and u/g cabling

> Grid connection

> Temporary works, contractors compound etc

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The Development Process

> Site identification & initial appraisal

> L/O negotiations & signing

> Anemometry

> EIA & design

> Public consultation, media etc

> Application

> Discharge planning conditions

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Environmental Assessment - Principles

> EIA is a process, not a “point in time” assessment

> Decision maker needs to have sufficient environmental information on the likely significant effects at the time the decision is made

> EIA is to identify and assess the likely significant environmental effects – not every conceivable effect, however small

> EIA is to assess the “realistic worst case”, not the worst imaginable however unlikely

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Environmental Assessment - Process

> Is collaborative, using best available data and information

> Is iterative, the design will evolve and respond to the environmental baseline and the assessment

> The development may not be completely defined – the EIA defines the “envelope” of effects that has been assessed

> There may be future tranches of environmental information to take account of changes in circumstances, or in the proposal itself

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Environmental Assessment - Process

> Scoping – identify where the likely significant effects are likely to come from

> Define baseline

> Define the development

> Identify and assess impacts

> Identify mitigation, design of the proposal evolves and responds

> Finalise the design of the proposal, complete assessment, produce the ES

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Environmental Assessment – Key Topics

> Landscape & Visual, including residential amenity

> Noise (operational & construction)

> Ecology & ornithology

> Hydrology, private water supplies

> Cultural heritage

> Site selection, but usually NOT alternatives

> Planning policies require the benefits of deploying renewables, and the achievement of renewables targets, should be given significant weight and balanced against any identified local environmental harm – but it is the realm of planning to make that balance, not environmental assessment

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Assessing Operational Noise from Wind Turbines

> PPS-22:

“The 1997 report by ETSU for the Department of Trade and Industry should be used to assess and rate noise from wind energy development”

> Successive Inquiry decisions and SoS decision letters have endorsed the principle that ETSU-compliance is the determinant of acceptability for commercial scale wind development

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Assessing Operational Noise from Wind Turbines

> PPS-22 Companion Guide:

“Well-specified and well-designed wind farms should be located so that increases in ambient noise levels around noise sensitive developments are kept to acceptable levels with relation to existing background noise”

“The report ‘The Assessment and Rating of Noise from Wind Turbines’ (ETSU-R-97) …gives indicative noise levels calculated to offer a reasonable degree of protection to wind farm neighbours, without placing unreasonable restrictions on wind farm development”

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Assessing Operational Noise from Wind Turbines – Principles of ETSU

> Noise should be assessed and controlled at nearest residential properties

> Noise limits may be different for “quiet day-time” when residents may be enjoying their gardens, and (counter-intuitively) higher at night when residents are indoors sleeping

> Both background noise at the residence, and noise from the turbines, will be a function of wind speed – so the analysis must be done as a function of windspeed

> 5dB above the local background at the property is a reasonable limit to set

> A fixed limit should apply where ambient noise is very low – turbines will be audible, but the noise level should not be unreasonable. This lower fixed limit is (for quiet daytime) between 35 and 40 dB L90, depending on 3 factors

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Assessing Operational Noise from Wind Turbines – Principles of ETSU

> Unless the turbine noise is very low – below 35 dB – then measurement of b/g noise at residential properties – and analysed as a function of wind speed at the wind turbine site – is crucial

> Any ETSU-related noise planning conditions will be set using the recorded b/g measurements

> Involvement of EHO at the time of selecting the properties – and precise locations at those properties – for the b/g m/ments is vital, or the entire assessment may subsequently be found inadequate

> Having set the noise limits using the measured data, the applicants consultant will then use standard predictive tools to ensure the predicted turbine noise from the development falls within the noise limits

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Assessing Operational Noise from Wind Turbines – Cumulative Effects

> Where there are several turbine developments in a neighbourhood, ETSU says the assessment must always be against the background without any turbines – ie the cumulative effect of all wind development must come within ETSU limits, the limit can’t be progressively inched up as each development comes on line.

> This can give assessment difficulties where there is an existing operational wind farm

> Noise conditions need to be set with care in a cumulative case – the condition for each development can only apply to that development, but the need is to ensure that cumulatively ETSU is met

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THANK YOU