Large-scale wind energy slows down winds and reduces turbine efficiencies

Posted: November 15, 2016 by oldbrew in research, turbines, wind
Tags:

Welsh windfarm [image credit: PA / BBC]

Welsh windfarm [image credit: PA / BBC]


If this research is correct, large windfarms could be losing a huge part of their potential output due to inadequate spacing, as Phys.org reports. Quote: “We found these dramatic effects at turbine spacings commonly used in present-day wind farms on land.”

Wind energy has been remarkably successful in providing an increasing share of cheap renewable energy. But can this trend continue to supply more and more renewable energy for decades to come?

A new study published by scientists from the Max Planck Institute for Biogeochemistry in Jena, Germany, lowers the expectations of wind energy when used at large scales.

How much wind energy can at best be generated? And how efficient are turbines going to be when more and more turbines are needed to generate more renewable energy? These questions were addressed in a study just published in the Proceedings of the National Academy of Sciences.

Every turbine removes energy from the winds, so that many turbines operating over large scales should reduce wind speeds of the atmospheric flow. With many turbines, this effect should extend beyond the immediate wake behind each turbine and result in a general reduction of wind speeds. This wind speed reduction is critical, as it lowers the amount of energy that each turbine can extract from the winds.

By accounting for this slowdown effect, the authors resolved a standing discrepancy between the high estimates for wind energy derived from local wind speed observations and small wind farms and the much lower estimates derived from large-scale estimates derived from climate models.

Dr. Lee Miller, first author of the study, explains: “One should not assume that wind speeds are going to stay the same with a lot of wind turbines in a region. Wind speeds in climate models may not be completely realistic, but climate models can simulate the effect that many wind turbines have on wind speeds while observations cannot capture their effect.”

The wind speed reduction would dramatically lower the efficiency by which turbines generate electricity. The authors calculated that when wind energy is used at its maximum potential in a given region, each turbine in the presence of many other turbines generates on average only about 20% of the electricity compared to what an isolated turbine would generate.

Dr. Axel Kleidon, group leader at Max-Planck-Institute for Biogeochemistry, admits that these scenarios of wind energy are hypothetical. Yet, he sees the results as highly relevant for the future expansion of wind energy. “We found these dramatic effects at turbine spacings commonly used in present-day wind farms on land.”

Kleidon plans to look into observations of present-day wind farms to see whether this effect can already be seen. This effect would imply that in order to maintain today’s high turbine efficiencies and favorable economics, the future expansion of wind energy should probably proceed with much greater spacing between turbines than what is common to wind farms of today.

Read more at: Large-scale wind energy slows down winds and reduces turbine efficiencies | Phys.org

Comments
  1. oldbrew says:

    ‘Kleidon plans to look into observations of present-day wind farms to see whether this effect can already be seen.’

    If it can be seen, a lot of money must have been wasted.

    ‘Wind energy has been remarkably successful in providing an increasing share of cheap renewable energy.’

    What nonsense is this?

  2. wolsten says:

    Reblogged this on Wolsten and commented:
    We knew this was likely – but good to see more research on this important issue which quantifies the effect as being a further 20% reduction over the already dire performance due to well known capacity factors.

  3. Joe Public says:

    A picture’s worth a thousand words ………

  4. ivan says:

    Joe, that picture was in my mind when I read the headlines. The problem is that the green renewable movement can’t see it.

  5. MJSnyder says:

    Wolsten – please note the article does not say “20% reduction”, but generation will be reduced to only 20% of that produced by a solitary turbine. Quite a difference.

  6. Climatism says:

    Reblogged this on Climatism and commented:
    “Climate Change” – the very thing they (windmills) try to stop, they actually change! 🤔

  7. In other news: Fish found to need water.

  8. ren says:

    Such a distribution of ozone means strong interference polar vortex …

  9. “Wind energy has been remarkably successful in providing an increasing share of cheap renewable energy”

    Really?
    This is more like it:

    Wind energy has been remarkably successful in sucking up an increasing share of taxpayers money to provide the illusion of cheap renewable energy”

  10. oldbrew says:

    Owl-inspired wing design reduces wind turbine noise by 10 decibels
    November 16, 2016

    ‘…the team has succeeded – through physical experiments and theoretical modeling – in using the downy canopy of owl feathers as a model to inspire the design of a 3-D printed, wing attachment that reduces wind turbine noise by a remarkable 10 decibels – without impacting aerodynamics.’

    Read more at: http://phys.org/news/2016-11-owl-inspired-wing-turbine-noise-decibels.html

  11. The off-shore plant shown—are the turbines lined up in a straight line behind each other? The wind plants I have seen on land are not. The turbines are offset. Is it common to line the turbines up or to stagger them? (Is the effect a photographic one perhaps?)

  12. oldbrew says:

    North Hoyle wind farm in Wales
    http://en.wikipedia.org/wiki/North_Hoyle_Offshore_Wind_Farm

    Part of Gwynt y Môr wind farm, North Wales – is or was world’s second biggest windfarm
    http://www.dailypost.co.uk/business/business-news/gwynt-y-mr-wind-farms-sub-stations-cabling-8668419

  13. Guess they do put the turbines in a row. That really makes no sense whatsoever. The picture in the blog post shows what I normally see–staggered turbines. Putting something that slows wind in a straight line? I guess just looking at the set-up, the flaw is apparent. Turbines behind the front lines produce progressively less energy as the ones in front slow the wind. Even without the picture of the wake behind them, this seems obvious.

  14. oldbrew says:

    ‘Researchers in the wind energy community are aware that the current generation of wake models underestimates wake losses in offshore wind projects with multiple rows of turbines. This phenomenon results from the cumulative drag imposed by so-called deep turbine arrays on the planetary boundary layer (PBL), the lowest layer of the atmosphere.’

    http://www.awstruepower.com/news-events/news-item/aws-truepower-research-confirms-deep-array-wake-effect-can-occur-in-onshore-wind-projects/

  15. oldbrew says:

    Wake turbulence is well-known to the airline industry.

    http://en.wikipedia.org/wiki/Wake_turbulence

    Obviously planes and wind turbines aren’t equivalent but questions of wind disturbance are common to both.

  16. oldmanK says:

    oldbrew, even geese and ducks knew that, long before humans took to the air. Formation flying.

  17. oldbrew says:

    Yes, various types of birds can do that.

    Birds That Fly in a V Formation Use An Amazing Trick
    http://phenomena.nationalgeographic.com/2014/01/15/birds-that-fly-in-a-v-formation-use-an-amazing-trick/

  18. oldmanK says:

    Missed the caption. Its ‘V’ – for Vortex.

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