Exclusive:Ministry of Defence objects to Borders wind farm over national security concerns
Concern has been raised about the height of turbines and low-flying planes.
The Ministry of Defence (MoD) has lodged a formal objection to a wind farm in the Borders over national security concerns.
The application, submitted to the Scottish Government’s Energy Consents Unit (ECU), is for 13 turbines up to 200 metres tall plus an energy storage facility southwest of Hawick.
If approved, the development, which has been scaled back from an initial proposal for 42 turbines, would generate around 94MW of clean power.
But the proposals have been met with opposition, with concerns over plans for turbines to be built within a designated safeguarding zone for the UK’s seismic array monitoring station at Eskdalemuir - the UK’s only facility to detect nuclear tests carried out anywhere in the world.
In its objection, the MoD warned the development, called Mid Hill, would have “an unmanageable impact on the operation and capability of the Eskdalemuir Seismological recording station.”
This included “detrimental effects on the performance of radar systems used to manage air traffic”, as well as military training and Air Traffic Control tasks.
Current planning controls include a 10 km exclusion zone and 50 km safeguarding zone for wind turbines.
The MoD said modern wind farms generate seismic noise which interferes with the ultra-sensitive seismic sensors at Eskdalemuir. Research has shown that the cumulative effect of turbines within a 50 km radius must be strictly limited to ensure the UK can meet its obligations under the Comprehensive Nuclear Test Ban Treaty. As a result, the MoD manages a finite “seismic noise budget” within that 50 km safeguarding zone.
According to its objection, “there is no seismic noise capacity available” – meaning additional turbines would push the cumulative vibration levels beyond acceptable limits and compromise the station’s international monitoring role.
The MoD said proposed turbines also fall within a tactical training and low flying area which would “introduce a physical obstruction to low flying aircraft operating in the area”.
The department said turbines over 150m must meet aviation safety lighting requirements, and confirmed it would require accredited MoD lighting specifications were the scheme ever to be approved.
The plans have also drawn opposition from local community groups.
Sarah St Pierre of the Borthwickwater Landscape Conservation Group said: “This region has been inundated with large-scale wind farm plans. Now we are being asked to sacrifice not only our landscape but a critical part of the international security network that monitors nuclear activity.
“The Borders has done more than its fair share.
“What the MoD has now confirmed is that there is no remaining seismic capacity for further turbines and that Mid Hill would undermine both nuclear monitoring and defence aviation. At some point we have to say enough is enough – this is not a suitable location and these impacts are not trivial.”
The Scottish Government has commissioned consultants, Xi Engineering, which is also advising the developer, Invenergy, on its proposals, to carry out a study on the vibration calculations within the exclusion zone.
Prior to the MoD’s objection, Invenergy published an aviation and radar assessment looking into the "impact on the Eskdalemuir Seismic Array”.
The report said: “Regarding Eskdalemuir, industry-led work is progressing to update vibration limits and improve compliance frameworks. The proposed development is expected to meet these requirements, although some technical adjustments may be necessary.
“With appropriate mitigation and planning conditions, it is anticipated that the proposed development can proceed without significant adverse effects on aviation, radar or defence interests.”
Invenergy was contacted for comment.
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