The world’s “most potent greenhouse gas” escaped during work on Scotland’s largest offshore windfarm, forcing the evacuation of workers, it has emerged.
More than 80 workers on a platform at the £3bn Seagreen project, which is 27km off Scotland’s Angus coastline in the North Sea, had to move to another platform after sulphur hexafluoride (SF6) escaped.
Energy companies are attempting to find alternatives to SF6, which is banned in Europe except for use in power generation where it is used as an insulating gas in switchgear machinery.
The US Environmental Protection Agency deems it the most damaging greenhouse gas and National Grid describes it as “one of the most potent greenhouse gases we know”. It can cause respiratory problems for humans if they are exposed in high concentrations and is harmful to the environment.
Seagreen is a joint-venture between SSE and TotalEnergies, with the platform managed by the specialist contractor Petrofac. The project will be Scotland’s largest and the world’s deepest fixed-bottom offshore windfarm when complete and is expected to enter commercial operation in mid-2023.
Two workers were checking equipment when a loud noise “like an air hose being disconnected” was heard. Workers shouted “gas leak” and “abandon rig”, according to Energy Voice, which first reported the story.
The incident occurred in June and has been brought to light by the North Sea trade unionist Jake Molloy, of RMT. Molloy told Energy Voicethat “the Seagreen incident is one event that did get reported to the trade unions by worried offshore workers.
“But how many go unreported, how is this policed and regulated, what are the reporting procedures? We need to know. It has to be properly managed.”
Petrofac said only 11kg of the insulating gas was emitted in the incident and that work restarted after 12 hours after standard procedures.
A spokesperson for Petrofac said: “Standard systems and procedures were immediately activated and site access restricted as a precautionary measure. Although the volume of CO2 equivalent did not meet the threshold for reporting, Petrofac documented and shared all lessons with relevant stakeholders including the HSE (Health and Safety Executive) and Marine Scotland.”
A spokesperson for SSE, which is responsible for the construction phase, said: “At the time of contract signing for the procurement of the transformer switchgear destined for the Seagreen project, which is currently under construction, there were no viable SF6-free alternatives available, capable of operating at all voltage levels needed, that could be considered for deployment to the project.”