The UK’s Office of Gas and Electricity Markets (Ofgem) is inviting bids to own and operate prebuilt transmission infrastructure connecting the Sofia offshore wind farm to the onshore electricity grid.
Bids are being invited in Tender Round 12 (TR12), being held under the Offshore Transmission Owner (OFTO) regime.
The OFTO tender process aims to partner offshore wind generators with efficient and competitive transmission operators.
“OFTO is part of Ofgem’s work to attract investors into the UK to boost growth and build a stable and secure energy system to deliver clean power to people’s homes,” stated Ofgem director of major projects Beatrice Filkin.
“As well as successfully attracting the investment needed to upgrade our energy system, OFTO also ensures that we as regulator deliver a good deal for consumers and keep bills as low as possible.”
OFTO was launched in 2009, and over the regime’s lifespan to date, winning bidders have invested over £11b in transmission links connecting 27 offshore wind farms.
The Sofia wind farm, operated by RWE, is under construction in the Dogger Bank area of the Central North Sea, 121 miles (195km) off the coast of Northeast England.
When fully operational, which is targeted for 2026, the wind farm will have a capacity of 1.4GW. The offshore portion of the project will include 100 SG 14‑222 DD turbines, each with a capacity of 14MW.
Installation of the monopile foundations for the turbines at the Sofia site began in May 2024.
RWE said at the time that depending on sea conditions, all 100 foundations were expected to be installed by the spring of 2025.
Wind turbine blades for Sofia are being manufactured at Siemens Gamesa’s manufacturing facility in Hull. The facility is preparing to begin manufacturing recyclable turbine blades this spring.
At Sofia, recyclable blades will be deployed on 44 of the 100 turbines.
The wind farm will be connected to the onshore electricity grid in North Yorkshire. The electricity transmission infrastructure for the project includes cables and both offshore and onshore converter stations and substations. Installation of the high voltage direct current (HVDC) export cable linking the Sofia site to the onshore grid began in 2023. The offshore converter platform was installed at the site in August 2024.
The submission deadline for bids under TR12 is May 13. Ofgem is then planning to launch another OFTO round, TR13, later this year.
TR13 is expected to be the biggest tender round to date, comprising transmission assets for three wind farms – Dogger Bank C, Inch Cape and East Anglia 3.
Ofgem anticipates bringing an average of £6b per year of OFTO assets to market each year up to 2030 as the pace of offshore wind development picks up. The regulator expects the average value of OFTO assets to rise as larger wind farms are developed further from shore. As a result, Ofgem says that up to £30b of OFTO assets could come to market by 2030.
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