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How Intermittent Is Wind Power?

May 1, 2015

By Paul Homewood 




According to Gridwatch, wind power averaged 1901GW during April, some 5.9% of UK total demand. Hardly awe inspiring, but the reality is really far, far worse, as this average hides huge variations within the month, as the chart below makes clear. (The Grid reports at 5-minute intervals).




As the wind ebbed and flowed, wind’s contribution ranged from a low of 79MW, or 0.2% of demand, up to 21.2%. Even within a day, there have still been huge variability, for instance on the 26th:




During the month, less than 1% of demand was being supplied by wind on 789 occasions, i.e. 9% of the time, For 34% of the time, it failed to exceed 3% contribution.


While wind farms are still no more than Mickey Mouse operations within the overall UK mix, the National Grid can cope with this sort of variability. When, however, wind capacity is tripled or quadrupled, as is the plan in the not so distant future, it will be another story.

  1. saveenergy permalink
    May 1, 2015 7:24 pm

    How can anyone contemplate running a country on such inadequate & intermittent energy sources ???
    To use a technical term…they’re Cr@p; ….but great for subsidy farming !!

    To see how much this is actually costing us look at UK’s 850+ Windfarms list
    Gives – Location, Capacity, Actual output, Capacity factor, Tariff details & Income for each site.
    (You should explore the rest of this site)

    See your local Windfarm instantaneous output on this Europe wide map
    (note- capacity is in MW but output is kW so ÷ DIVIDE output by 1,000 to compare)

    • AndyG55 permalink
      May 1, 2015 9:27 pm

      “How can anyone contemplate running a country on such inadequate & intermittent energy sources ???”

      Yet this is what the “alarmista” want to hold the developing countries too.

      Highly variable, unreliable, unusable, irregular energy systems. as opposed to the solid reliable, usable energy of coal and/or gas….

      .. and all because of a failed CO2 warming hypothesis.

      Its tantamount to criminal discrimination, forcing poor countries to remain in poverty.

      • December 19, 2015 7:48 pm

        so you want to live in a world of smoke and kill te planet wit coal ?



      • December 19, 2015 8:15 pm

        Learn to spell and then come back IDIOT!!

  2. May 1, 2015 8:33 pm

    “20 years is a wind turbine’s life span,
    What happens then? Is there a plan?
    Thousands of turbines will then need replacing,
    A new energy crisis we will be facing…..”
    Read more:

    • AndyG55 permalink
      May 1, 2015 9:21 pm

      A wind apostle on another forum mentioned that there is a thriving scam business whereby the nacelle and blades can be replaced.. usually needed after 5-10 years (not 20 years)

  3. May 1, 2015 8:44 pm

    The more intermittent power there is in the system, with priority over other generation, the higher the cost of managing the fluctuations will be.

    The power companies can already see that investing in non-renewables is unprofitable. The obvious conclusion is there will be a power crisis somewhere along the line as so-called back-up (i.e. what we use most of the time) goes ever further into decline.

    • AndyG55 permalink
      May 1, 2015 9:22 pm

      UK, Germany. South Australia? … who will be first with a major system collapse ?

  4. Joe Public permalink
    May 1, 2015 8:59 pm

    Doncha just love it when those ‘green’ ‘leccy suppliers promise to provide their gullible customers with “100% green” electricity?

    Who do they cut off when <1% of grid is supplied via windmills.

  5. AndyG55 permalink
    May 1, 2015 9:18 pm

    With that data, someone ought to be able to answer the question…

    ‘What percentage of nameplate capacity can wind GUARANTEE to deliver 95% of the time.?”

    I would much rather one of the wind preachers do the maths. 😉

    • AndyG55 permalink
      May 1, 2015 9:52 pm

      But for April, that value was pretty darn PATHETIC. (3.6% of nameplate)

      Maybe over a longer period the % might climb a bit,
      maybe April was just a really bad month for wind…

      but its sure not the sort of electricity supply I would want to have to rely on if I was trying to do something mundane and existence based like store food or cook !

  6. May 1, 2015 9:50 pm

    “How Intermittent Is Wind Power?” Not intermittently intermittent but permanently intermittent.

  7. nigel permalink
    May 1, 2015 9:53 pm

    My sister-in-law was upset when they installed a big (20 turbines) set a mile from her. She was afraid of incessant noise. Well, usually, they barely move. So, no problem really.

    • gary permalink
      May 1, 2015 10:18 pm

      that’s funny

  8. saveenergy permalink
    May 1, 2015 10:00 pm

    Energy decisions should be in the hands of power engineers, physicists & civil engineers, not scientifically challenged green dreamers or politicos looking for a new trough to feed from.

    This is what they’ve hoisted on us –
    According to the UK wind industry, Britain has 6,091 industrial wind turbines with a total capacity of 12GW (see ).

    ( Plus “Over 25,000 small and medium wind systems have been installed in the UK since 2005” – )

    And 5GW of solar PV. (see )
    ≈ 17 GW of capacity

    As I write this –
    UK Demand is 31 GW ….
    Wind is currently supplying 1.5 GW (see )
    Solar ≈ 0 GW …..So where’s the other 15.5 GW (92% of Wind & Solar pv capacity ) that we are paying £billions in subsidies per yr for???

    Red Ed Millibands 2008 Climate Change Act, has locked us into this madness that The International Energy Agency suggest will cost us an extra £1,300 billion over the next 20 yrs (enough to run the NHS for 12yrs).
    More info here –

  9. May 2, 2015 1:38 am

    Texas has a lot of windmills. One time they lost 4GW of wind power off their gird in less than an hour. Wind just quit.

    Please post more graphs like this Paul. Its a great and simple illustration as to the unschedulable nature of “renewables.”

    People need to understand you must have spinning deserve for the entire range of the graph for the entire duration. (if you want a reliable electric distribution grid).

    • Lance permalink
      May 2, 2015 2:27 am

      Bingo, Willybamboo. Wind Energy requires 80% rated capacity backup power by coal/gas/nuclear/oil because wind energy is unpredictable. That means taxpayers or ratepayers fork over 180% of energy costs to supply what they could have had for about half the end game cost. If wind power were so very viable, wouldn’t those “evil” energy companies have exploited such a cost effective resource already? Or is wind only cost effective when politicians force taxpayers to fund indefensible idiocy for the sake of environmentalist special interests?

      • AndyG55 permalink
        May 2, 2015 9:16 pm

        No, Lance. wind requires around 95-97% back-up of its nameplate.

        I have shown that in several places.

        You cannot rely on it to supply much more than 3-5% of its nameplate most (95%) of the time.

  10. Lance permalink
    May 2, 2015 2:20 am

    Wind is intermittent as described below:

    Wind:Intermittency Study

    Low Benefit of Industrial Wind

    Click to access LowBenefit.pdf

    Utility Scale Wind Power Impacts

    Click to access victoria-emissions.pdf

    Wind Power: Less for More

    Click to access boonej-lessformore.pdf

    Wind “power” is taxpayer and ratepayer subsidized, non-dispatchable, stranded, redundant, worthless, generation. It is the “bird chopper” De-Luxe, an affront to every environmental species protection act that has ever been exempted in favour of destroying a national energy grid and fleecing the populace for no net benefit.

    Every supporter of Wind Energy ought to have their necessary health, work, and home devices solely supported by wind energy for about 7 days. None but the delusional would ever propose wind as anything but a fanciful whim of illiterate and irresponsible acolytes after such a meaningful week.

  11. John F. Hultquist permalink
    May 2, 2015 2:34 am

    From the NW USA:

    Another 5 min update of power — wind is green line

    • AndyG55 permalink
      May 2, 2015 2:58 am

      John, from the data download at the top, the amount that is always available 95% of the time, is about 55MW

      Out of around 4700MW installed… that’s a LOUSY 1.2% of nameplate.

      It really is a pathetic energy supply system, isn’t it !

      • May 2, 2015 8:35 am

        it’s 3x worse thanyou think !!
        we have in exess of 12,176 MW of installed wind capasity
        see my post above @ May 1, 2015 10:00 pm

      • AndyG55 permalink
        May 2, 2015 9:21 pm

        I found the 4700MW value on another page of the linked web site, referring to the same region in NW USA as the supply data John mentions.

        I think you are referring to UK installed capacity, which is around 12GW.

      • saveenergy permalink
        May 2, 2015 11:54 pm

        Yes, I was referring to UK installed capacity, sorry for any confusion.

      • AndyG55 permalink
        May 3, 2015 1:35 am

        If you look up further in the thread, you will see that the 95% reliability point for UK wind was 3.6% of nameplate.

      • AndyG55 permalink
        May 3, 2015 1:36 am

        note, figure above was for April.

      • saveenergy permalink
        May 3, 2015 8:50 am

        Hi Andy,
        you may like this-
        Interactive switchable graph showing Live UK Grid status – demand & generation by all fuels

        Shows MW & %; real-time, hourly, daily, monthly. Graphs go back to 2011
        (you can switch the different fuels on/off & zoom, – follow the onscreen instructions)

  12. May 2, 2015 6:42 am

    The first graph is typical of wind power everywhere across Europe. In Germany the y-axis is about 4 times the size, hence the grid problems they are encountering (partly mitigated by Germany being connected to the European grid). The pro-wind lobby insist that there is no problem because the wind power can be forecast very accurately, but that is just one of the many lies they use. Inspection of the ‘wind forecast out-turn’ graphs at often shows this not to be the case, with the out-turn often being 3 or 4 times larger or smaller than forecast.

  13. Ben Vorlich permalink
    May 2, 2015 7:10 am

    There are a number of sites which give real time or nearly real time data for EU countries. I’ve never been able to find any non-UK ones for historical data, apart from the GridWatch French data.


    Germany (not quite real time)



    European windspeed map

  14. johnmarshall permalink
    May 2, 2015 11:37 am

    And it’s these variations that cause the Grid problems.

  15. May 2, 2015 12:23 pm

    As I knew a lot of it and we will have a lot of fun and a lot of people are poor and some are rich

  16. May 2, 2015 12:44 pm

    “US electric carmaker Tesla Motors has unveiled batteries that can power homes and businesses as it attempts to expand beyond its vehicle business.

    Chief executive Elon Musk announced the firm would build batteries that store solar energy and serve as a back-up system for consumers during blackouts.”

    Why should we need back-up for blackouts?

    “The rechargeable lithium-ion battery unit would be built using the same batteries Tesla produces for its electric vehicles, analysts said.

    The system is called Powerwall, and Tesla will sell the 7kWh unit for $3,000 (£1,954), while the 10kWh unit will retail for $3,500 (£2,275) to installers. ”

    It doesn’t say how long the batteries would last.

  17. saveenergy permalink
    May 2, 2015 4:42 pm

    I find this an interesting tool –
    Interactive Globe (click on earth ) for Wind, Temperature, Ocean currents,,54.73,284

    • The IEA is pleased to present the “Monthly Electricity Statistics” report, which provides timely and consistent electricity production and trade data for all OECD Member Countries. The “Monthly Electricity Statistics” provides data that are fully reconciled to the definitions of the annual reporting. Also on this page you can find a historical dataset going back to jan 2000

    Canada – Ontario –

    Lots more Wind turbine Outputs here –

  18. Detl permalink
    May 2, 2015 5:52 pm

    The problem is, that you can build as many windmills in an area as you want. The power that ist allways available will remain at zero. For Germany this is proven in the following article:

    As the article was translated by google, unfortunately there are some translation errors…

  19. THX1138 permalink
    May 3, 2015 1:30 am

    I don’t know about Britain or Europe, but over 30 years ago, here in America, I worked for a windpower company as their data processing head (I know, I was young and naive). They constantly played with figures, for example reporting “capacity” as if it was being delivered, when in fact one lone several kilowatt machine was running on the entire property (out of at that time 1100 machines). The utility companies played a game wherein they paid a fee for not providing the distribution “capacity” for that windfarm, year in and year out, all based on the “representative” output of that lone wind turbine. The entire thing is a scam top to bottom, front to back. Meanwhile, I couldn’t believe the size of “executive bonus” checks I kept seeing flowing off the printer. They cut short my career when, I think, they figured I was catching on, they made it all my fault, of course, and under extreme duress.

    Certainly this type of corruption is not new to anyone here? Or maybe some people are just not used to thinking about the size and scope of it, and the incredible lies they will weave to keep the scheme (scam) going?

    • saveenergy permalink
      May 3, 2015 8:53 am

      You are not alone, same things are happening in UK & around the world.

  20. May 4, 2015 8:27 pm

    Wind energy is green energy, I agree! But if we built those wind parks in the middle of the sea or of the ocean, like it happened in the Baltic and in the North Sea, for example, we could influence the ocean and the water temperature and, thus, the entire climate. It’s a fact that we should keep in mind and take into account when thinking about green energy from offshore wind mills.

    • saveenergy permalink
      May 4, 2015 11:16 pm

      @ smamarver,
      2 points;
      1 ) wind power generation is far from being ‘green energy’, no space to elucidate here.
      (suggest you look at – whole life costing, from material manufacture to disposal, constant backup requirements & checkout how ‘green’ any energy storage is. )

      2 ) you obviously have little grasp of engineering or geophysics to even think wind parks could influence the ocean and the water temperature, let alone the entire climate !!

      • May 5, 2015 6:27 am

        Saveenergy, for the first point, I agree with you, the costs are very high. For the second one, here is a study of what happened in the North Sea and Baltic:

      • saveenergy permalink
        May 5, 2015 12:16 pm

        @ smamarver, sorry…..but

        1) A clue is in the title – ‘A fascinating THEORY on the impact of naval warfare on climate’

        2) The article talks about “ship propellers are plowing through the sea stirring the surface layer”

        3) No mention of Wind turbines, except “Several thousand offshore facilities on the bottom of the sea or anchored offshore rigs divert currents at sea and influence tides and currents as a permanent resistance against the normal flow of huge amounts of ocean water. (Fig. 3-8) The result is like stirring hot soup. Warm water will come to the surface and the heat will supply the atmosphere with warmth. ”

        That theory doesn’t take account of stratification !!

        4) Water temp profile shows the surface heating up in line with solar radiation with a time lag at 40m; It’s similar to the Water temp profile of the Irish Sea.

        5) Wind turbines extract an infinitesimal amount of energy from the wind; they do not have any meaningful effect on the water, let alone the entire climate.

  21. January 24, 2016 5:23 pm

    Interesting—Denmark has one of the highest, if not actually the highest, percentage of it`s electricity generated by wind. Perhaps no surprise that it has the highest electricity prices of any industrialized country— John.

  22. Ash permalink
    May 13, 2016 12:16 pm

    Fossil fuel and nuclear ppower generation may be more convenient and cost effective for us all (everyone knows this), but they are also prime candidates for the collective Darwin award. People should be supportive of solutions to maintaining our lifestyles with the REAL threat of global warming and trying to find ways to accomodate the issues with such solutions, rather than either ignorantly or selfishly abhorring change and small personal losses (such as the spoiling of the look of the countryside). This is what the government is doing with renewable energy subsidies and this is why I travel less than 5000 miles a year in my car and take my pedal bike instead wherever possible (I’m not keen on the public transport services on offer to me, unless I’m travelling to a big city), and why I feel a responsibility not to have more than 2 children (sorry economists, global population really should stabilise for the sake of the planet) and why I use as little electricity or other fuels as possible.

    Unfortunately, I think most people are going to have to wait until global warming causes some really significant humanitarian or other disasters before siding with me on this and then will be all too late.

    On the other hand we could just consider the whole planet a resource to be enjoyed during its temporary existance and continue as we are doing, accepting at some point people on Earth will have to endure huge amounts of suffering because of it! I am just too selfless.

    • May 13, 2016 2:51 pm

      Whatever CO2 reductions the UK makes, it will be inconsequential compared to global increases occurring.

      BTW – If you think global warming is such a real risk, why are anti nuclear?

      • Ash permalink
        May 13, 2016 4:08 pm

        Whatever CO2 reductions any one individual on this planet makes is inconsequential, just like virtually any political vote. But if we all thought like that nothing would happen. Furthermore, the UK produces far greater CO2 emissions per head of population than most other countries; we are 43 of some 400 odd, according to (not that I’m saying one should take wikipedias word on anything, just it is an easy source to find), so our actions here in the UK are more consequential than most places.

        On the nuclear front, I believe the disposal ofradioactive waste and potential for such severe catastrophe, although negligible risk per plant, to be too great. You can use fast breeder reactors and other methods to help with some of the wastes, but there is still a major problem of waste handling that is only going to grow with use; nuclear is a short sighted solution.

      • May 13, 2016 4:23 pm

        UK emissions account for only 1% of global ones.

      • Ash permalink
        May 13, 2016 4:42 pm

        That is irrelevant – UK population is only 64 million of 7.4 billion globally = 0.009 % of global population. Just because someone lives in a country with more people, their actions are more meaningful then? Your answer: “UK emissions account for only 1% of global ones.” is naïve – emissions should be dealt with on either a per capita or, ideally, per land area (accounting for negative emissions, such as biomass) (in which case I’d expect UK really will look poor) basis.

      • May 13, 2016 6:17 pm

        I was simply making the point that even if the UK totally decarbonised it would make naff all difference globally. When the rest of the world joins in, fine.

        As for your suggestion we look at “per land area”, I can only assume you have been at the Jamaican Woodbine! Are you seriously suggesting that countries with densely concentrated populations like the UK or Holland should accept lower CO2 per capita? Or perhaps you think we are overpopulated and should therefore get rid of a few million!

      • It doesn't add up... permalink
        May 13, 2016 6:58 pm

        Not very numerate are we? UK population is 0.9% of the global total. The problem is that China, with its large population, is now also by some way the world’s biggest emitter: failure to reduce emissions there makes other attempts to reduce emissions largely irrelevant.


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