ScottishPower Renewables, a subsidiary of Iberdrola, and Dong Energy have opened the 389MW West of Duddon Sands offshore wind farm, which is a major renewable project for the UK.
The new facility is located in the Irish Sea.
UK Energy Secretary Edward Davey cut the ribbon for the €2bn facility, which is equipped with 108 of Siemens' 3.6MW wind turbines and has more than 200km of undersea cable installations.
Standing almost 20km away from the Barrow-in-Furness coastline in North West England, the now-operational wind farm will generate enough electricity to power 280,000 UK households.
A new £50m offshore wind terminal has been built at Belfast Harbour to support the project, which is the first purpose-built offshore wind installation and pre-assembly harbour in the UK and Ireland.
Energy secretary Edward Davey said: "This wind farm will generate enough clean electricity to power more than a quarter of a million homes and give the local economy a major and sustained boost.
"We want an energy mix that is built on diverse, home-grown sources to make sure our supplies are clean and secure. Wind has a huge role to play, which is why the UK is the best place in the world to invest in offshore wind projects."
ScottishPower chairman Ignacio Galan said: "West of Duddon Sands is the first offshore wind farm in the UK to use such highly advanced construction methods, allowing us to complete the project months ahead of schedule.
"It has tested the UK's ability to deliver major renewable energy projects, in terms of workforce skills, supply chain depth, facilities and logistics."
Dong Energy wind power executive vice-president Samuel Leupold stated: "The UK is an important market for our company and we have committed investments totalling more than £5bn here over the last decade. We expect to invest a similar sum again by 2020, with another offshore wind farm under construction, and four more in planning or development."
The West of Duddon Sands facility is the eighth operational wind farm for Dong Energy in the UK.
Image: Located in the Irish Sea, the Duddon Sands offshore wind project will supply power to almost 280,000 UK homes. Photo: courtesy of ScottishPower Renewables.