London Array offshore windfarm

Year:2013

Duration:2 years

Cost:£1.8bn

Country: Thames Estuary, UK

What did this project achieve?

Design, build and install a landmark windfarm way out to sea in the Thames Estuary

The London Array is a 175 turbine offshore windfarm 20km off the coast of Kent in the outer Thames Estuary. It's the largest operational offshore windfarm in the world. Its 630MW output makes it the largest windfarm in Europe by capacity.

The project is seen as a landmark event for the world's renewable energy industry and credited with paving the way for a new generation of bigger windfarms.

Phase 1 of the project opened in 2013. Phase 2 was denied planning permission in 2014 amid concerns about the impact on red-throated divers – a protected aquatic bird found in the area.

The windfarm is called the London Array as the power it produces goes to the London grid.

Difference the windfarm has made

The London Array produces enough power for nearly 500,000 homes in the UK every year. That's enough to supply two thirds of homes in Kent.

By producing clean energy the project reduces pollution and other environmental damage associated with using fossil fuels to produce electricity.

The windfarm reduces harmful CO2 emissions by more than 925,000 tonnes a year.

How the London Array was installed

Built over 2 years, 1,000 people worked on the London Array to build 175 turbines and 2 offshore substations. The team also laid 250km of cables over the project's 95 working days.

Weather and sea conditions in the Thames Estuary were major challenges for engineers working on the London Array. The area can be windy and depending on tides the sea can be up to 25m deep.

The turbines are big - taller than the London Eye - and the tide and weather had to be just right when lifting them and their foundations into place.

The project team constructed much of the windfarm on land. The substations, for example, were built and fitted out in Belgium and then floated to the Thames Estuary by barge.

Generators for the windfarm were installed using a jack-up barge – a boat fitted with long support legs that can be raised or lowered. At the construction site the legs are jacked down on the sea floor and the hull – and its load – are raised above sea level. This means waves push against the relatively slender legs and not the bulkier hull.

The largest individual items for engineers to get into place were the 2 offshore substations. Each weighed around 1,250 tonnes, about the same as 200 African elephants.

"​‌

This is a great day for Kent and a great day for Britain. London Array has been built by some of the bravest seamen, the most talented engineers and hardest workers.

David Cameron

Prime Minister at the opening of the London Array, 4 July 2013.

People who made it happen

  • Designed and built by energy companies EON, Ørsted and Masdar.
  • Substations designed and built by Future Energy, a consortium of engineers Fabricom, construction company Lemants and marine engineers Geosea.

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