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The Vagaries Of Wind Power

December 15, 2012

By Paul Homewood




I reported on Wednesday that in the previous 24 hours wind power in the UK had contributed as little as 0.6% of the nation’s electricity output.

Reader, Paul M, kindly gave me details of a useful little tool, which is shown above and gives information on daily, weekly, monthly and annual electricity generated by the various methods.


Zooming in, for instance,on the monthly graph for Hydro/Pumped/Wind/Bio (the 3rd column), we can see that the low levels reported earlier this week are by no means unusual.




Peak demand for electricity is close to 60GW, so wind, at its maximum of around 4GW, contributes between 6 and 7% in optimal conditions, but as little as 1%, as we saw this week. In the last 30 days, there appears to be eight days when the contribution was less than 1GW.

The yearly figures also show an awful lot of volatility, with most months seeing periods with little wind power. Look for instance at early February – there is a period of about two weeks when the total was consistently around or below the 1GW mark, except for a couple of days.




The grid can cope at the moment with the loss of 5% of its capacity, when the wind does not blow. But when there are ten times as many windmills, can it cope with the loss of 50%?

Indeed the equation is actually likely to be worse than that. It is reasonable to assume that most of the current crop of wind turbines are located in favourable areas. As more and more are built, they are going to be set in areas where the wind is not as strong or reliable.

The only way to compensate for a loss of output of this magnitude, other than the strategically unacceptable option of relying on imported power from France, would be to carry enough spare gas generating capacity.

Gas currently contributes about 39% of total output. Coal, Oil and Nuclear, most of which are due to close in the next few years, add another 50%. If wind power is to replace the latter, wind capacity would have to be increased by a factor of 12.

Yet nearly all of this wind capacity would need to be backed up by standby gas generators, of which we will need more than double the number we currently have.

It actually get worse! Not only do we need to decarbonise our electricity, we also need to do the same with heating and transport. For instance, we use more energy for heating than for transport or the generation of electricity. To hit CO2 targets, fossil fuels for these will have to be replaced by “low carbon” electricity. In other words, a lot more windmills, backed up by an lot more gas fired power stations ticking over.

More on this later.

  1. Robin permalink
    December 15, 2012 7:50 pm

    Thanks Paul for the link. I have downloaded the huge file and need to do some serious pruning, like reducing the observations to one per hour before i can really do some decent analyses. The raw file is too large for my system to handle, but little will be lost by reducing the data since there is a great deal of autocorrelation between hourly values. I find their graphics not too comfortable to look at, since I can’t seem to get them at a reasonable size. The numbers are much more useful to me. I hope I can get sufficiently to grips with Excel to be able to do this clerical work. I’d never use Excel for statistics!

  2. coldoldman permalink
    December 16, 2012 12:28 am

    Hi Paul

    Maybe not as comprehensive as yours but I like
    for a quick look. You can see all the bits on the left, I have mine set to show, by default.

    Generation By Fuel Type (table)
    Generation By Fuel Type (graph)

  3. Brian H permalink
    December 17, 2012 3:46 am

    What ‘mill promoters won’t admit: the economy and grid cannot ever tolerate near-zero supply, or even significantly slashed supply. And wind delivers those in spades. Frequently.

  4. January 14, 2013 10:43 am

    Ahhh but you don’t understand – once the “Smart Grid”(TM) is in place, the forces of proper living will be able to control demand, so that no one who really needs electricity will go without. Only those extraneous, frivilous users will be cut off. Demand will be adjusted to meet supply, as described in the 5-year plan.

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