One of the world’s largest offshore wind farms — it can power half-a-million homes a year — has been fully built off the coast of England.

Turbine, London Array

After four years under construction, with 175 massive wind turbines from Siemens, England’s game-changing offshore wind power farm, the London Array, is finally complete. The farm, one of the largest in the world, is about 20 kilometers (12 and a half miles) off the coasts of Kent and Essex, and covers an area that is about 100 square kilometers (38 square miles).

The London Array can provide 630MW of electricity, which is about the size of a large coal or nuclear plant, and can power over half-a-million homes in the U.K. per year. It is feeding directly into London — hence the name — and is helping England meet its carbon emissions reduction targets.

British Prime Minister David Cameron officially inaugurated the London Array late last week. Power companies Dong Energy and E.ON own 50 percent and 30 percent respectively, and Masdar owns 20 percent.

Building the giant offshore wind farm hasn’t been without controversy — back in 2008, oil giant Shell, which was one of the original backers, pulled out of the deal, leaving the farm’s construction uncertain.

It’s hard to imagine how powerful the London Array is without seeing its size and scale. Here’s a variety of photos that the group released late last week:


Updated at 2:40 PM BST with the square miles of the area that the London Array spans across.

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  1. What part of the revenue from the London Array is being put by for its maintenance, upgrading, and eventual replacement?

  2. They cant power half a million homes – they cant power even 1 home , its impossible due to their irratic nature

    1. By your logic, no power plant can ever power a home since it will have to go offline at some point. The “uptime” of an array like this with this kind of geographic spread is far higher than your imagination can reach.

  3. Thanks a lot for your passionate introduction, Katie. :-) I work each day to bring Offshore Windfarms to realization and see how many people at our company put their heart into it.

    Currently, there seems to be some kind of misunderstanding what wind turbines can and cannot do. I saw some comments on some last article and here I once more see strange opinions:
    No, in total they are not at all irratic and especially not at the coast with constant winds due to day/night temperature changes and considering the very flat North Sea.
    No, they have reproduced all power we used for their production after half-a-year therefore they produce 19.5 years more power.
    Whether it’s economically feasible that’s a question we need to solve within the next decade.

    I am a big fan of GigaOm and I hope that you will stay for many years to come. Thanks a lot for your articles and insights!

    1. What a load of rubbish.

      The wind resource off the East Coast is only slightly better than onshore and can be checked by looking up the official output figures for existing turbine arrays on the Renewable Energy Foundation ‘renewables obligation generators’ database, on the REF website.

      The Balancing Mechanism website shows all UK metered output and short-term forecasts. Tthere are frequent occasions when even the short-term (15min) forecast is wildly adrift of realised output; this means that little reliance can be given to wind output.

      The entire UK wind fleet is frequently producing the square root of sweet FA, as we have seen in recent weeks. For example, the entire UK wind fleet was producing as little as 24MW, the headline capacity of 6 standard offshore turbines, on 17 June.

  4. I wonder how many millions of birds this wind farm will kill over its lifespan…

    1. Kate, do you have those statistics?

  5. What is the cost of the wind farm vs a coal plant or nuke plant of the same size?

    1. Almost certainly worse than coal today and almost certainly better than nuclear which has become almost impossible to build cost effectively, unfortunately.

      1. I can’t find any Google hits on London Array and LCOE (the best measure of what a project’s cost of power truly is). Bloomberg New Energy says offshore find will match coal and gas on cost by 2016, but presumably this project will be more costly given it was already built.

      2. majorkongridesthebomb Mark Wednesday, July 17, 2013

        Actually offshore wind is more expensive compared to nuclear power (even the legacy magnox reactors that are going offline). Onshore wind is far more competitive in terms of price though. Also, the next generation of Siemens offshore wind turbines look to be a vast improvement over the current turbines (like the ones used at the London Array).

    2. Levelised costs per kWh show that offshore wind costs approximately 2-2.5 times the cost of nuclear (including decommissioning and storage) or gas. See Mott Macdonald on the DECC website: https://www.gov.uk/government/publications/uk-electricity-generation-costs-mott-macdonald-update-2010

      And, irrespective of the numbers of turbines built, you still have to build the nuclear, coal or gas plant to provide the base load generation needed to keep the lights on.

    3. majorkongridesthebomb TexasScout Wednesday, July 17, 2013

      Not sure on the exact price, but Ed Davey proposes a strike price of £155 per MWh. The EPR nuclear strike price is estimate at £105 per MWh. Coal and other fossil fuels are typically much cheaper (ignoring the long term financial and human costs incurred by climate change).

    4. majorkongridesthebomb TexasScout Wednesday, July 17, 2013

      Not sure on the exact price, but Ed Davey proposes a strike price of £155 per MWh for offshore wind (which is subsidised too). The estimate strike price for the EPR nuclear facilities (privately funded) is £105 per MWh. Coal and other fossil fuels are typically much cheaper (at least before we calculate the long term financial and human cost of climate change).

  6. Do not beat me up for this picture but it’s good to get the perspective right:

    Please be aware that the imprint will change if we install more wind turbines so yes, it’s a valid argument.

  7. what is the total cost of the project? were there cost-overruns compared to the original budget? all giant energy projects (especially those that are subsidized with taxpayer dollars) are judged on this basis, these are important facts to report in stories like this!

    1. They are not subsidised with “taxpayer dollars” in the UK.

      Subsidies are paid from consumer bills. This means that costs hit the poorest hardest, with no allowance for ability to pay.

      Offshore wind power generation costs ca. 3 times wholesale cost, plus massive extra costs in grid restructuring and strengthening.

  8. With the powerful winds in Dubai, they should build these there.

  9. KnowledgeMama Tuesday, July 9, 2013

    If you click thru to the Londay Array link, the site lists the 3 shareholders have invested 2.2Bgbp in the project. I say well done!

  10. I agree with a comment below, they should consider building in Dubai. By the way, great pictures.

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