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Letters / The dirty little secret of the renewables industry

There is good reason to be sceptical of the reassuring environmental claims being made by the Scottish Government, SIC and the energy companies involved with the building of wind farms in Shetland.

Much criticism has rightly been centred on the industrialisation of Shetland’s hills in areas that are ecologically sensitive. What has received less attention are the Upper Kergord Substation (currently under construction) and the proposed South Yell 132kV Switching Station. Both are designed to link the various windfarms together in order that power from them can subsequently be exported to the National Grid.

According to Scottish & Southern Electricity Networks (SSEN), “This is more efficient than taking the Energy Isles and Beaw Field connections back separately to Kergord. It will also be available to connect future developments on South Yell.”

Both the Upper Kergord substation and the proposed Yell switching station will be using Gas Insulated Switchgear (GIS).
At an information event in Burravoe in May this year, Scottish & Southern Electricity Networks (SSEN) were keen to point out that the building being used to house the GIS in south Yell would have minimal visual impact on the immediately surrounding landscape.

There were also plenty of freebies on offer – chocolate bars and SSEN branded drinks bottles. No attention was focused on the Gas Insulated Switchgear, or the gas that is used within it. This is hardly surprising.

Gas Insulated Switchgear has been described as the dirty little secret of the renewables industry. It contains a gas called Sulphur hexafluoride (SF6). This gas is 23,500 times more efficient at trapping heat in the atmosphere than Carbon dioxide and, once in the atmosphere, will remain there for over 1,000 years. Indeed, SF6 HAS THE HIGHEST GLOBAL WARMING POTENTIAL OF ANY SUBSTANCE.

It is readily acknowledged by the National Grid that leaks of SF6 occur during construction and decommissioning of the switching stations that use it. According to, global annual emissions of SF6 are about 8,100 tonnes, which is equivalent to the CO2 emissions of 100 million cars.

That is more than the annual sale of cars worldwide. Just one kilo of SF6 has the equivalent global warming effect of 24 people taking a return flight to New York.

It is also instructive to note that research carried out by the electrical company Eaton, suggests that throughout the lifetime of GIS switching stations, leaks of SF6 could be up to 15 per cent of what is used in them. Presumably, SIC has developed and will be publishing a robust series of monitoring measures in relation to both the Kergord substation and proposed switching station in south Yell.

The price of pursuing Net Zero at all costs is already being paid by wildlife – with the disturbance and destruction of peatland habitat; a habitat that unless badly damaged is the best terrestrial carbon sink on the planet.

Sadly, further peatland in pristine and near-natural condition is being sacrificed for the achievement of net zero with the two new wind farms on Yell (quite why this is taking place is a mystery, as it is wholly possible to build wind farms in places where such harm can be avoided).

Add to that the installation of GIS apparatus, and it is obvious that genuine concern for the landscape, the natural world and those who live in areas where this is all taking place, is negligible within local and national government. Those who stand to benefit financially from choosing to allow these switching stations to be built on their land really ought to reflect on what they have done.

Frank Hay
Chairman Sustainable Shetland


South Yell Switching Station Information event May 2023:  
Sulphur hexafluoride explained  
Grid switchgear uses SF6, the world’s most potent greenhouse gas. How do we regulate it? 
Climate change: Electrical industry’s ‘dirty secret’ boosts warming (BBC)


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