British ESO proposes network design to connect upcoming Celtic Sea floating wind farms

The Crown Estate has invited proposals from the pre-qualified bidders in the Round 5 seabed leasing process which will award up to 4.5 GW of floating wind capacity in the Celtic Sea. Around the same time, National Grid ESO issued a recommended network design to connect the upcoming floating wind farms to the national grid.

This is the first time in the UK that developers know how their new offshore wind farms will be connected to the grid while still going through the leasing process, according to ESO and The Crown Estate.

ESO’s recommended design involves connecting up to 3 GW into two locations in South Wales and up to 1.5 GW into the South West of England, with each of the three proposed offshore wind farms having its own connection to the onshore electricity network.

The grid connection proposals are for one high-voltage direct current (HVDC) connection into a potential new South Wales Connection Node and two connections utilizing high-voltage alternating current (HVAC) technology into Carmarthenshire and North Devon. 

“The Celtic Sea design is unique to other network design exercises previously undertaken by the ESO as developers have yet to bid for the opportunity to develop in the three areas of seabed identified by The Crown Estate for this leasing round. This new approach to the sequencing will allow developers to make a more informed bid based on the network recommendations, reducing risk”, ESO stated on 13 August.

“It is also allowing the ESO to take a new approach on the connections queue for this Round 5 capacity by effectively ringfencing the 4.5GW in advance, so that we can proceed efficiently with the connection contract process when the seabed Agreements for Lease are awarded by TCE”.

On August 13, The Crown Estate said the second phase of the leasing process got underway on August 8, following the conclusion of the initial pre-qualification questionnaire (PQQ) in June 2024.

The initial phase was launched in February, marking the official opening of the floating wind tender.

The Crown Estate says that, following the first phase, it was “able to move forward with a strong pool of Prequalified Bidders, all of whom have demonstrated their suitability to proceed”. 

The now-initiated second phase will see the pre-qualified bidders submitting their project plans, including details on how their plans will support the delivery of wider social and economic benefits for onshore communities.

“Bidders are being encouraged to be ambitious in developing their proposals, which could include initiatives linked to skills development, apprenticeship opportunities, community impact, sustainable procurement and nature restoration”, The Crown Estate states in a press release from 13 August.

“Bidders will also need to outline how they intend to work with ports in the execution of their plans, identifying both a primary and alternative port that they propose to use for the assembly of the windfarms. These plans will then form contractual obligations as part of the lease agreement for successful bidders”.

The bidders will be notified about the outcome of this part of the tender in the first quarter of 2025. After that, The Crown Estate will start the second stage of the invitations to tender – the auction. This stage is expected to commence by the end of Q1 2025 and be concluded in the second quarter of next year.

The auction next year entails a requirement for the bidders to execute a preferred bidder letter (PBL) ahead of the auction. The bidders will then participate in a dynamic auction (ascending clock auction) which will determine a single preferred bidder for each site and will stop when there is a single and different preferred bidder for each site.