Applied & Environmental Geophysics

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There are currently no small wind turbines approved by the MOD for installation around Eskdalemuir

Vibrations from Small Wind Turbines

Our previous work was concerned with vibrations from large wind turbines, the vibration levels from small and micro turbines was not known when the EKA safeguards were originally developed. However, in June 2008 MoD agreed an interim position, pending further research. The interim position is that if a proposed small turbine (defined as having rated-power ≤ 50 kW) within the statutory consultation zone is calculated to contribute ≤ 0.00001 nm to the budget, then this is considered negligible, and does not contribute to the noise budget managed by DE.

Small Wind Turbine MoD/DE recently became aware of substantive research into vibration from small and micro wind turbines (including monitoring and modelling) by Professor Styles and his group, the Applied and Environmental Geophysics Research Group (AEG), at the University of Keele.

In the light of this, and possible future research by AEG, the MoD has decided on the following pragmatic approach to extend the interim position on what can be considered a negligible contribution to the Eskdalemuir seismometer array “noise budget” when considering consent to build and operate small turbines in the statutory consultation zone around EKA.

The intention of the extension to the current interim position is to allow effective exploitation of the research by AEG to allow an ad hoc assessment by AEG and MoD experts of whether specific design-types of small turbine can be permitted in the consultation zone. This extended approach is itself an interim measure pending development of a generic approach to safeguard EKA.

The extension to the current interim position for small turbines within the statutory consultation zone around EKA will now mean,

The 10 km exclusion zone for building wind turbines around EKA remains.
The interim limit of 0.00001 nm remains for the statutory consultation zone from 10 to 50 km around EKA unless,

After appropriate research AEG present suitable report-based evidence to MoD experts to allow assessment of the vibration frequency-response for a specific design-type of small wind turbine. (After an initial assessment by MoD experts, informal exchanges may be required to clarify specific technical points, and the report revised as necessary.) It will be left to the industry to commission and fund this research.
The assessment by MoD experts confirms that the specific small turbine design- type presented has been shown to excite negligible seismic energy in the frequency passband of interest for EKA, and therefore does not contribute to the noise budget.

AEG will maintain on this website a list of the approved small wind turbine design-types and the report-based evidence submitted. The list of approved small turbine design types will be added to on an ad hoc basis as and when research by AEG progresses to the point where an appropriate report can be presented to and approved by MoD experts.

The full MOD guidance document is available as a PDF file below.