United Kingdom

United Kingdom

World's largest offshore wind project online

UK: Danish developer Ørsted has officially placed its 659MW Walney Extension online, surpassing the 630MW London Array site as the world's largest offshore wind project.

Walney Extension had achieved first power in September 2017 and its final turbine was installed in April 2018 (pic: Ørsted)
Walney Extension had achieved first power in September 2017 and its final turbine was installed in April 2018 (pic: Ørsted)

It consists of 40 MHI Vestas V164-8MW turbines, uprated to 8.25MW, in its 330MW West phase, and 47 Siemens Gamesa SWT-7.0-154 machines in the 329MW East phase.

The turbines — covering an area of 145km2 of the Irish Sea — were installed on monopiles and transition pieces manufactured by German firm EEW SPC, Danish group Bladt Industries and, what was, their UK joint venture Offshore Structures Britain (OSB).

The turbines deliver power to the UK’s grid via more than 200km of export cables provided by Swiss firm ABB and installed by Boskalis’ subsea cable business, formerly known as VBMS. Boskalis also provided the inter-array cables for both the East and West sites.

Walney Extension features two offshore substations, each weighing 4,000 tonnes. The substations’ jacket foundation height is 50 metres, while the topside height is 18.5 metres.

The project demonstrates the acceleration of offshore wind in terms of size and scale, turbine supplier MHI Vestas claimed.


Walney Extension consists of 7MW and 8.25MW turbines.

By comparison, London Array, now the world’s second largest wind farm, was commissioned in 2013 and comprises 175 units of Siemens Gamesa’s SWT-3.6-120 model.

Matthew Wright, Ørsted’s UK managing director, said: "The UK is the global leader in offshore wind and Walney Extension showcases the industry’s incredible success story."

Ørsted divested half of the project in November 2017 — 25% each to Danish pension funds Pensionskassernes Administration (PKA) and Pension Forsikringsaktieselskab (PFA).

Walney Extension was awarded a final investment decision-enabling CfD subsidy by the UK government in April 2014 and was approved in November 2014.

It delivered first power in September 2017 and its final turbine was installed in April 2018.

Record breaker... for now

It's moniker as the world's largest offshore wind project will be short-lived, however.

Construction is underway at ScottishPower Renewables' 714MW East Anglia One site, and Ørsted's 1.2GW Hornsea Project One — both in the UK — and due online in 2020.

In the Netherlands, the Blauwwind consortium reached financial close on the 731.5MW Borssele III/IV project, which is due online in 2021, as is Innogy's 860MW Triton Knoll UK site, also financially arranged. 

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