Erebus Floating Wind Project in Celtic Sea, UK

Project title: Erebus Floating Wind Project 

Project location: Celtic Sea, UK

Client: BlueGem Wind – Simply Blue Energy and Total S.A.

Project Summary: In February of 2020, OWC was contracted to provide pre-FEED owner’s engineering and project development services to Simply Blue Energy and Total’s Erebus floating wind project located in the Celtic Sea. Following our successful role guiding the project through this phase, OWC entered another large contract, in November 2021, to provide owner’s engineering services for the FEED phase of the floating wind project.  

About the wind farm

Erebus was the first Test and Demonstration (T&D) floating offshore wind project awarded an AfL by The Crown Estate in Welsh waters. The project, with a maximum capacity of up to 100 MW, is located 49 km from the West Wales coast with landfall planned in West Angle Bay, Pembrokeshire. The project comprises up to 10 WTGs, with a maximum blade tip of 270m, using the WindFloat semi-submersible floating platform.

Our scope of work

OWC’s support on the project began in 2020 during pre-FEED and included project design, geoscience and site investigation, cable, electrical, and WTG engineering and Owners Engineer. In addition OWC worked closely with MarineSpace and ITPEnergised to manage the EIA and permitting process, securing the first Marine Licence and Section 36 Consent for a FLOW project in Welsh waters.

Through the pre-FEED and FEED stages, OWC provided owner’s engineering and project development support services, including: 

  • Management of onshore and offshore consenting 
  • Procurement and management of geotechnical, geophysical, and metocean site surveys 
  • Energy yield analysis and metocean management 
  • Offshore and onshore layout design and optimisation 
  • Electrical network design and associated studies 
  • Grid management support 
  • Ports and assembly strategy together with stakeholder engagement 
  • Transport & installation studies 
  • Operations and maintenance strategy development and modelling 
  • Subsea array and export cables together with landfall studies 
  • Project cost modelling 
  • Comprehensive package management, engineering and project management functions (e.g. risk, interface, schedule) 

Key roles as an integrated team:

  • Owner’s Engineer, including Principal Designer 
  • Package Managers 
  • Engineering Manager 
  • Risk & Interface Management 


Erebus was first in a pipeline of T&D projects in the Celtic Sea, ahead of Round 5 which will award up to 4.5 GW of renewable energy capacity by 2025, and a further commitment of 12 GW of capacity by the UK Government. Being the first mover in the region posed numerous engineering and consenting challenges, exacerbated by an aggressive programme and integration of new technologies.

  • Technology maturity and development risks 
  • Supply chain requirements  
  • Consenting – aligning technical and consenting requirements 
  • Environmental and site conditions i.e. deep waters 
  • Ports infrastructure, transport and installation 
  • Operations and maintenance and the unique challenges of floating wind 

Environmental and Consenting Challenges

  • New region with limited baseline data
  • No precedent for consenting FLOW in Welsh waters
  • Aggressive programme to meet CfD deadline
  • Navigational impacts and risks in Celtic Sea
  • Unique regional ornithological, marine mammal and benthic sensitivities
  • Supply chain availability
  • Relevant skills availability (technical and marine)
  • Geotechnical and environmental conditions for floating wind

Value added

OWC provides unique value to each project to ensure our Client’s success. With OWC’s support, Blue Gem Wind was granted the first marine license and Section 36 for floating offshore wind in Wales. 

Broad-ranging technical, engineering and consenting support through an integrated team model 

Client access to specialists from across the broader ABL group and extensive international floating wind project expertise  

Early coordination and collaboration between specialists, with direct collaboration between Package Managers and environmental specialists

Dedicated project management team, overseeing engineering packages and EIA and consenting scopes

“We are pleased to continue the relationship with OWC and partners. Project design and development is a core skill of the UK supply chain, and we are delighted to award this contract to a UK business.”​

David Groves, Commercial Manager, Blue Gem Wind 

“We see the continued collaboration with OWC as an important step in submitting our planning consent for Erebus in December and preparing the project for construction.”​

Mike Scott, Project Managing Director, Blue Gem Wind 

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