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What is the Walney Extension? Analysing the world’s largest offshore wind farm

In September the UK welcomed the official unveiling of the largest offshore wind farm in the world - but what is the Walney Extension?

Appropriately acting as the masthead of the largest offshore wind energy producer in the world is the globe’s largest offshore wind farm - the Walney Extension.

The UK’s offshore wind capacity currently runs at more than seven gigawatts (GW) – more than any other country – with another 7GW in the pipeline.

Owned and operated by Danish energy firm Orsted, the Walney Extension is the single largest contributor to this world-leading tally, with its capacity of 659 megawatts (MW) also making it more productive than any other farm of its kind.


What is the Walney Extension?

Located in the Irish Sea to the north-west of the English coast, the Walney Extension spans 56 square miles of water and comprises 87 turbines, with the tallest standing at the sky-scraping height of 195 metres.

It launched in September 2018 and Orsted, a Fredericia-based company with just under 6,000 staff, claims the farm has the potential to power 600,000 homes while reducing 943,282 tonnes of carbon dioxide from the atmosphere each year.

Speaking at its official unveiling, Orsted UK managing director Matthew Wright said: “The UK is the global leader in offshore wind and Walney Extension showcases the industry’s incredible success story.

what is the walney extension
The Walney Extension features 40 MHI-Vesta turbines, which stand at 195 metres (Credit:

“The project also marks another important step towards Orsted’s vision of a world that runs entirely on green energy.

The North West region plays an important role in our UK offshore wind operations and our aim is to make a lasting and positive impact here.

“We want to ensure that the local community becomes an integral part of the renewable energy revolution that’s happening along its coastline.”

In November, the Walney Extension was the most productive wind farm in the UK, generating roughly 70% of its maximum output - enough to power 466,740 homes in the country.

It is part of a larger set of wind farms owned by Orsted in a project known as the Walney Wind Farm, which comprises three separate sections: Walney Phase 1, Walney Phase 2 and now the Walney Extension.

The first section was officially unveiled in 2010 and the addition of the third in September last year means the facility now houses 189 turbines, with a total capacity of 1,026MW.

what is the walney extension
The Walney Extension is located off the North-West coast of England (Credit:


The UK offshore wind sector leading renewables progression

Compared to its offshore generation, Britain’s onshore wind energy sector comprises considerably more turbines (7,544 compared with 1,830) and operational projects (1,934 as opposed to 37).

However, the extent of this disparity is not reflected in the outputs of both sectors, with onshore producing 12,688MW to offshore’s 7,898MW, highlighting the potential of the latter to become the focal point of UK renewable energy as it prepares to double its capacity over the coming years.

In January 2018, wind energy accounted for more of the UK’s energy needs than nuclear power (19.1% compared to 17.9%), with renewables contributing more than 30% to the country’s overall energy demand throughout the year.