IN Brief:
- Ofgem has named Diamond Transmission Partners preferred bidder in offshore transmission tender round 11 for Dogger Bank B.
- The consortium comprises Diamond Transmission UK Limited and Chubu Electric Power, and has not yet received the final licence.
- The proposed offshore transmission owner must establish funding, contractual, operational and regulatory arrangements before asset transfer.
Ofgem has selected Diamond Transmission Partners as preferred bidder to acquire and operate the offshore electricity transmission assets associated with the 1.2GW Dogger Bank B wind farm. The decision, published on 5 November, was issued under regulation 21(1) of the Electricity (Competitive Tenders for Offshore Transmission Licences) Regulations 2015 and relates to offshore transmission owner (OFTO) tender round 11. It advances the competitive transfer process but does not yet make the consortium the licensed transmission owner or confirm that the assets have changed hands.
Diamond Transmission Partners comprises Diamond Transmission UK Limited and Chubu Electric Power Co., Inc. Under the regulator’s notice, it must resolve several matters before becoming the successful bidder. These include putting in place contractual, funding, regulatory and operating arrangements needed for the asset transfer and the grant of the offshore transmission licence. The regulator also requires the consortium to complete a bilateral agreement with the holder of a coordination licence and to accede to the System Operator – Transmission Owner Code. Any other matters identified by Ofgem must also be resolved to its satisfaction.
The next stage is consequently a regulatory and operational handover process. The consortium has emerged from competitive bidding, but must demonstrate that the funding, contracts and operating arrangements are ready for a transfer of the transmission assets. Offshore transmission ownership places continuing obligations on the licensee to maintain availability, manage the export connection and comply with relevant system rules. The 5 November decision identifies the preferred party without settling an asset transfer value, annual allowed revenue or the date when the new licence will take effect.
Dogger Bank B is the second of three phases forming the wider Dogger Bank Wind Farm in the North Sea. Each phase has a planned capacity of 1.2GW, giving the combined development an eventual generating capacity of 3.6GW. Dogger Bank B lies approximately 131km from shore at its closest point and covers a project area of roughly 599 square kilometres, according to the development’s published project information. This geography shapes the requirement for substantial offshore substations, export cables and onshore network interfaces to carry power from the turbines to the national electricity system.
The Dogger Bank A and B phases connect towards the existing Creyke Beck substation near Cottingham in the East Riding of Yorkshire. Their submarine export cables make landfall north of Ulrome, with approximately 30km of underground cable connecting towards converter-station infrastructure near Cottingham and onward to the grid. The wind farm’s project description identifies two converter stations for the combined A and B connection arrangements. Those route and interface details describe the wider electrical system; the regulatory notice does not list each individual component to be transferred under the B-specific OFTO transaction.
The offshore infrastructure must collect power from the wind turbines, transform and convert it, and export it through high-voltage cables to the mainland network. Dogger Bank B uses an offshore converter platform and onshore conversion equipment to transfer electricity over a long North Sea route. The offshore and onshore electrical interfaces involve protection, communications, cooling and auxiliary systems as well as the main power apparatus. Those assets are the subject of the eventual regulated transmission service, while the wind turbines and their generation output remain part of the developer’s generating business.
The OFTO model separates generation ownership from long-term ownership and operation of certain offshore transmission connections through a competitive tender. Rather than allowing a project developer to retain the regulated connection indefinitely as part of the generating business, Ofgem appoints a licensed offshore transmission owner after assessing qualifying bids. The selected owner must deliver transmission services in accordance with the licence and relevant industry codes. This framework is intended to create competition for ownership and operating obligations while keeping the continuing transmission service regulated.
The B-phase tender sits in Ofgem’s eleventh Offshore Transmission Owner tender round, which followed earlier qualification and bidding stages. Regulation 21(1) notice of a preferred bidder is followed by the steps specified for successful-bidder status under the competition rules. Only after those arrangements are completed to the regulator’s satisfaction can the process move to the necessary licensing and asset-transfer decisions. The stages matter operationally because responsibility for network performance, maintenance and availability must pass between the developer and the new transmission owner without ambiguity.
Operational readiness will require coordination with the generator and the wider electricity system. The required bilateral agreement with the coordination-licence holder is one part of that framework. Accession to the System Operator – Transmission Owner Code establishes participation in the arrangements that govern interfaces and procedures between relevant network parties. These requirements are distinct from equipment construction and commissioning tests, although the eventual owner must be satisfied about the assets it is taking into service. Ofgem’s decision gives no basis for claiming that all technical acceptance, legal and funding steps have already been completed.
Dogger Bank Wind Farm is being developed by SSE Renewables, Equinor and Vårgrønn, with three 1.2GW phases giving a planned total of 3.6GW. The tender concerns only the transmission connection associated with Dogger Bank B. It neither grants Diamond Transmission Partners ownership of the wind turbines nor constitutes a new construction contract for Dogger Bank A or C. The wider project’s installation activity will continue on its own timetable while the B-specific ownership and licensing arrangements are resolved.
Diamond Transmission Partners must now conclude the required funding, contracting and operating arrangements, enter the specified bilateral agreement and accede to the System Operator – Transmission Owner Code. Once Ofgem is satisfied with those steps and any further conditions it imposes, the regulator can progress the successful-bidder and licence process. The immediate change is a preferred-bidder selection for the 1.2GW Dogger Bank B transmission link; the final transfer and licensed operation remain separate decisions.
