Are wind farms slowing each other down?

Posted: June 4, 2021 by oldbrew in Energy, Uncertainty, weather, wind
Tags: ,


German Chancellor Merkel surveys an offshore wind site [image credit:]

Wind ‘farms’ are allergic to each other it seems, sometimes leading to sizable drops in output. Awkward when space isn’t unlimited, some of the best sites are already taken, and the plan is to multiply the existing fleets. Weather dependency is even greater than expected.
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The expansion of wind energy in the German Bight and the Baltic Sea has accelerated enormously in recent years, TechXplore.

The first systems went into operation in 2008. Today, wind turbines with an output of around 8,000 megawatts operate in German waters, which corresponds to around eight nuclear power plants.

But space is limited. For this reason, wind farms are sometimes built very close to one another.

A team led by Dr. Naveed Akhtar from Helmholtz Zentrum Hereon has found that wind speeds at the downstream windfarm are significantly slowed down.

As the researchers now write in the journal Nature Scientific Reports, this braking effect results in astonishingly large-scale low wind pattern noticeable in mean wind speeds. On average, they extend 35 to 40 kilometers—in certain weather conditions even up to 100 kilometers.

The output of a neighboring wind farm can thus be reduced by 20 to 25 percent, which ultimately leads to economic consequences. If wind farms are planned close together, this wake effects need to be considered in the future.

Combination of climate and wind farm data

With their study, Naveed Akhtar, an expert in regional climate modeling, and his colleagues took a look into the future and assessed the wind characteristics for a medium-term target state of offshore expansion.

They used the computer model COSMO-CLM, which is also used by weather services and which is able to resolve weather situations regionally in detail—in this case for the entire North Sea and combined it with the future wind farm characteristic—their area and the number and size of the turbines.

They used the wind farm planning for the North Sea from 2015 as a basis. This contains , some of which have not yet been built.

Braking effect especially in stable weather conditions

Naveed Akhtar used the COSMO model to calculate the wind speed over the North Sea for the period from 2008 to 2017 covering a range of different weather conditions.

The results clearly show that we will face a large scale pattern of reduced wind speed, which show largest extensions during stable , typically the case in March and April. In stormy times, on the other hand—especially in November and December—the atmosphere is so mixed that the wind farm wake effects are relatively small.

Full article here.

  1. Gamecock says:

    ‘which corresponds to around eight nuclear power plants’

    A new metric!

    ‘The first systems went into operation in 2008’

    Maybe it would have been better to do this study a decade ago.

    But, you know, wind power is so cheap, even with this affliction, why bother? Why did Nature Scientific Reports even report this?

    And whoda thunk that windmills downstream from other windmills would receive less wind. Except for everybody.

  2. Graeme No.3 says:

    Years ago there was a picture of Horns Rev1 showing the effect of the wake from the blades. This seems to be a copy.

    The ‘farm’ comprised 7 rows of 8 turbines, and it was calculated that if row3 and row6 were removed that the output would increase.

    And this is a similar picture of Horns Rev3.

  3. Graeme No.3 says:

    That was what Google turned up as Horns Rev1 & 3, but they look identical.

  4. bill treuren says:

    Has anybody sailed a boat and noticed the impact of wind shadow.

    The 8 nuclear power stations is stupid because you still need backup and if its nuclear the fuel is largely zero cost so you would never switch it off to allow some bird choppers a run.

  5. JB says:

    Really? Somebody had to conduct a study to figure out what kids discover? Stand behind someone else to get out of the breeze. The windless side of the barn.

  6. Phoenix44 says:

    And are we supposed to believe this has no other effects? If you remove energy from the atmosphere like this, what happens? Dors wind increase because there’s still the pressure effect? What happens to local weather conditions? What happens to biological systems that use the wind? Potentially important changes no-one seems to have thought about.

  7. oldbrew says:

    Wind Energy – The Facts says:

    Wake Effect

    Wind turbines extract energy from the wind and downstream there is a wake from the wind turbine, where wind speed is reduced. As the flow proceeds downstream, there is a spreading of the wake and the wake recovers towards free stream conditions. The wake effect is the aggregated influence on the energy production of the wind farm, which results from the changes in wind speed caused by the impact of the turbines on each other. It is important to consider wake effects from neighbouring wind farms and the possible impact of wind farms which will be built in the future. [bold added]
    – – –
    Wind Energy – The Facts (WindFacts) was a European project financed by the Intelligent Energy – Europe programme of the Executive Agency for Competitiveness and Innovation that ran from November 2007 to October 2009.

  8. Mike Wattam says:

    Next thing, they’ll be discovering a bloke called Isaac Newton. This will give an opportunity to the obsessed, to discredit him and other ‘inventors’ of similar generations. Clearly they were wrong. Only Google and that bloke I met in the pub the other night, are right.

  9. oldbrew says:

    Published: 03 June 2021
    Accelerating deployment of offshore wind energy alter wind climate and reduce future power generation potentials

    ‘Our results emphasize that wind energy in the North Sea can be considered a limited resource. With the current plans to install offshore wind energy farms in the North Sea locally resource exploitation limits are reached. Better planning and optimization of locations are required that consider the development of wind wakes under realistic multi-year atmospheric conditions.’
    – – –
    Adverse wind speed effects can occur upto 40 kms. downwind of the source, in the North Sea.

    ‘A limited resource’ 👍

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