The first geotechnical seabed surveys for a proposed second phase to Scotland’s largest offshore wind farm have been completed.

The surveys, which were carried out at SSE Renewables’ Seagreen site, off the Angus coast, examined conditions, ahead of up to 36 new turbines being added to the 114 already fully operational.

Seagreen, is a joint venture partnership between SSE Renewables and TotalEnergies and forms part of SSE's £20.5bn NZAP Plus investment plan.

It is Scotland’s largest and the world’s deepest fixed-bottom offshore wind farm, with the deepest foundation installed at a record depth of 58.6m below sea level. The phase 2 project is known as Seagreen 1A.

Andrew Train, Project Director for Seagreen 1A, said: 
“We are pleased to confirm the completion of another geotechnical offshore survey at the Seagreen 1A site. This builds on existing site data and is another step forward in the project following the unanimous support from East Lothian Council in the approval of the onshore substation design last year.

“The geotechnical works, using industry best practices, will enhance and broaden our understanding of the seabed conditions across the full project site. As always, we remain committed to continuing to build on community and supply chain links and relationships within the local and wider areas.

“Scotland and the UK have set ambitious renewable energy targets and Seagreen 1A has the potential to form a vital part of delivering on that ambition and will play a key role in the delivery of SSE’s Net Zero Acceleration Plus Programme.”

Seagreen is already capable of generating enough green energy to power more than 1.6 million homes*, equivalent to two-thirds of all Scottish homes and will displace over 2 million tonnes of carbon dioxide* from electricity generated fossil fuels every year.

The vessel, that carried out site investigation works, the 90m long ‘Connector’ arrived on site and completed phase one works in a period of 10 days during February.

This involved specialist cone penetrometer testing (CPT) at almost 100 locations.

Using dynamic positioning (DP) technology the vessel repeatedly held positions while thin rod sensors penetrated into the seabed at depths of up to 15 metres to allow the team to learn more about the seabed composition and understand if the proposed turbine foundation locations are suitable and appropriate for the technology proposed.

Proposals for the Seagreen 1A turbine foundations include using innovative and similar three-legged suction caisson technology which allowed the original Seagreen project team to push boundaries and set new records.

The suction caisson technology allows the turbine foundation to fix securely to the seabed penetrating to a depth of up to 11 metres under the seabed.

Phase two of the geotechnical works is expected to commence later this year and should take around two weeks to complete. The second phase will involve Vibrocore (VC) works along the proposed export cable route from the offshore site to the landfall at Cockenzie.

* 1.62 million homes powered per annum based on Typical Domestic Consumption Values in Britain (Medium Electricity Profile Class 1, 2,900kWh per household; OFGEM, January 2021), typical 50% offshore wind load factor, and installed capacity of 1.1GW.
* Two-thirds of homes in Scotland based on Household Estimates Scotland 2019 (National Records of Scotland, June 2020). Quoted 2.23m t/CO2 reductions per annum based on expected annual output against average 446 t/CO2 per GWh (BEIS Digest of UK Energy Statistics, July 2020).

KeyFacts Energy: SSE UK country profile