# Offshore transmission owner

Offshore Transmission Owners (OFTOs) operate and maintain offshore electric power transmission infrastructure in Great Britain, delivering electrical power from offshore wind farms to the National Grid. OFTOs may design and build this transmission infrastructure, but in most cases wind farm developers construct the electrical transmission assets and then sell them to an OFTO once complete.

## Operation

In the British electricity market, different functions of the electricity system are separated, with this practice beginning in the 1980s. The activities of generators, transmission operators, system operators, distribution operators and suppliers are separately licensed by Ofgem, with a single business unable to perform multiple functions due to UK Competition Law.
The groundwork for the offshore transmission regime was laid by the Energy Act 2004, with the first offshore transmission license being awarded in 2011. As of 2021, all the offshore transmission infrastructure in Great Britain has been built by wind farm developers, who are then required to sell their transmission assets to a separately licensed Offshore Transmission Owner. The divestment must take place before the Generator Commissioning Clause date, on which the exemption from this requirement lapses.
Divestment is managed via a regulated tender process administered by the energy regulator Ofgem. Qualifying bidders are required to conduct due diligence before submitting a bid to purchase the assets for transfer value determined by Ofgem and receive their bid Tender Revenue Stream (TRS) for a fixed license period. Ofgem then appoints a Preferred Bidder who negotiates the purchase terms with the Developer, after which Ofgem awards a transmission license and the transfer takes place.

## Offshore transmission operators

| Windfarm | Developer | Capacity (MW) | Final Transfer Value (£m) | OFTO | License Award Date |
| Tender Round 1 ||||||
| Robin Rigg | E.ON | 180 | 65.5 | Transmission Capital Partners | 2 March 2011 |
| Gunfleet Sands | Ørsted | 173 | 49.5 | Transmission Capital Partners | 19 July 2011 |
| Barrow | Ørsted and Centrica | 90 | 33.6 | Transmission Capital Partners | 27 September 2011 |
| Walney 1 | Ørsted, SSE and OPW | 184 | 105.4 | Blue Transmission | 21 October 2011 |
| Ormonde | Vattenfall | 150 | 103.9 | Transmission Capital Partners | 10 July 2012 |
| Walney 2 | Ørsted, SSE and OPW | 184 | 109.8 | Blue Transmission | 26 September 2012 |
| Sheringham Shoal | Scira | 315 | 193.1 | Blue Transmission | 27 June 2013 |
| Greater Gabbard | SSE and RWE | 504 | 317.1 | Equitix Group | 26 November 2013 |
| Thanet | Vattenfall | 300 | 164.8 | Balfour Beatty | 17 December 2014 |
| Tender Round 2 ||||||
| London Array | Ørsted, E.on and Masdar | 630 | 444 | Blue Transmission | 10 September 2013 |
| Lincs | Ørsted, Centrica, and Siemens | 270 | 307.7 | Transmission Capital Partners | 4 November 2014 |
| Gwynt y Môr | RWE, Stadewerke München and Siemens | 574 | 351.9 | Balfour Beatty | 11 February 2015 |
| West of Duddon Sands | Ørsted and Scottish Power Renewables | 388 | 268.9 | West of Duddon Sands Transmission Plc | 19 August 2015. |
| Tender Round 3 ||||||
| Westermost Rough | Ørsted, Marubeni and GIB | 205 | 172.3 | Transmission Capital Partners | 3 February 2016 |
| Humber Gateway | E.ON | 219 | 173.3 | Balfour Beatty | September 2016 |
| Tender Round 4 ||||||
| Burbo Bank | Ørsted | 258 | 193.9 | Diamond Transmission Partners | 25 April 2018 |
| Tender Round 5 ||||||
| Dudgeon | Equinor | 402 | 297.9 | Transmission Capital Partners | 5 November 2018 |
| Race Bank | Ørsted | 573 | 472.5 | Diamond Transmission Partners | 9 October 2019 |
| Galloper | RWE | 340 | 281.8 | Diamond Transmission Partners | 24 February 2020 |
| Walney Extension | Ørsted | 600 | 446.6 | Diamond Transmission Partners | 1 June 2020 |
| Rampion | E.ON | 400 | 279.5 | Transmission Capital Partners & International Public Partnerships Limited | 12 November 2021 |
| Tender Round 6 ||||||
| Hornsea One | Ørsted | 1218 | 1170 | Diamond Transmission Partners | 1 March 2021 |
| Beatrice | SSE, Red Rock Power Ltd, The Renewables Infrastructure Group and Equitix | 588 | 437.9 | Transmission Capital Partners | 27 July 2021 |
| East Anglia One | ScottishPower Renewables and Vattenfall | 714 | 692.6 | Transmission Capital Partners | 15 December 2022 |
| Tender Round 7 (in progress) ||||||
| Moray East | Diamond Green Limited, Moray Offshore Renewable Power Limited, Delphis Holdings Limited, China Three Gorges Limited | 900 | 666.1 | Transmission Capital Partners | 15th February 2024 |
| Triton Knoll | RWE Renewables, J-Power, Kansai | 857 | 572.7 | ETEPCO | |
| Tender Round 8 (in progress) ||||||
| Hornsea Two | Ørsted | 1,368 | 1141.2 | Diamond Transmission Partners |
| Tender Round 9 (in progress) ||||||
| Seagreen Phase 1 | Seagreen Wind Energy Limited | 1,140 | | ETEPCO (preferred bidder) |
| Tender Round 10 (in progress) ||||||
| Moray West | Moray Offshore Windfarm (West) Limited | 882 | | |
| Neart Na Gaoithe | Neart na Gaoithe Offshore Wind Limited | 448 | | |
| Dogger Bank A | DBA Projco | 1,200 | | ETEPCO (preferred bidder) | |
| Tender Round 11 (in progress) ||||||
| Dogger Bank B | DBB Projco | 1,200 | | | |