Is wind power reliable? – An authoritative article from David Millborrow who is technically experienced and numerate, unlike many other commentators

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(This technically numerate, evidence based article, shows that wind does not need any extra back up when it is not windy, due to the blindingly obvious fact that the existing power stations can simply be started – no new ones have to be built.  Why this obvious fact escapes other commentators remains a mystery. 

Millborrow shows that the extra costs of spinning reserve to cope with the greater variability of wind power is around a mere £7.6/MWh, with 40% wind and no capacity credit, or £5.8/MWh without. ie 0.76p/kWh –  0.58p/kWh.)

Editorial introduction: The UK has committed itself to a very ambitious target to increase its wind powered generation capacity by 2020. The EC’s 15% renewable energy target implies that renewable electricity, much of its wind power, will have to provide between 35-40% of electricity supplies. This has caused concerns in some quarters that the UK ‘s security of supply will be placed in jeopardy. However, others say this concern is overplayed. In the following article, David Milborrow* debunks myths surrounding wind power’s reliability:

The cold snap at the beginning of January encouraged several letters to the press making  much of the fact that there had not been much wind during this time. “How foolish of the government to rely on it”, is the usual conclusion.
 The letter writers seemed unconcerned (or unaware) that there was also a shortage of nuclear output during the cold snap. In early January, only about 50% of nuclear capacity was online. 5000 MW was “missing” — but the electricity system continued to do its job.
The reasons it continues to deliver are twofold:
electricity systems do not rely exclusively on any one technology or fuel and, secondly, there is always a significant “plant margin” – currently about 30% in Great Britain – so that is why we can cope with low wind and a significant shortage of nuclear.
The “plant margin” is the difference between the total plant capacity and the expected peak demand. In round numbers, the peak demand this winter is expected to be around 60,000 MW and there is 75,000 MW of plant. The margin is therefore around 25%, which is slightly higher than the theoretically desirable figure.
For some reason, there is a disproportionate amount of interest in the ability of wind energy to contribute to peak electricity demands. Setting aside the fact that there is a lot of extremely competent analysis that points to the fact that, statistically, wind can make a contribution, that is not the major role of wind energy. It does save fuel, however, and that contribution is more valuable.

winter peaks and in the case of wind, it leads to an assumption that the “winter quarter” capacity factor is appropriate — around 35%. Both these figures are quoted in National Grid’s “Winter Outlook Report 2008/9”.
“Capacity credit” is a statistical concept, as noted above. The ratio between the “firm capacity” and the rated capacity is sometimes termed the “capacity credit”, but a more common definition, in the context of wind, is :- “The reduction, due to the introduction of wind energy conversion systems, in the capacity of conventional plant needed to provide reliable supplies of electricity.” (1)


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8 comments on “Is wind power reliable? – An authoritative article from David Millborrow who is technically experienced and numerate, unlike many other commentators

  1. The bigger question is wha to do with wind energy at times of off-peak demand.
    The answer must be storage. The classic is pumped storage. ‘Ripple Control’ aka ‘smart metering’ can store off-peak energy as heat (or cold) at the consumer.
    ITM Power offer hydrogen storage there. They reason that the wires are dimensioned to cope with peak demand all the way to the 13 A socket. (Actually there is some averaging on the ring main and as you get further from the consumer.)
    Therefore hydrogen could be generated at the consumer much of the time making it possible to use the available wind energy nearly all the time, thereby saving fuel.
    It might be even more cost effective to generate the hydrogen at the windfarm because according to Ing Tetzlaff the cost of electrical infrastructure is at least 10x that of gas.

  2. Tend to agree with you.
    Pumped storage is pretty useless though, as it is very expensive and Dinorwig can only deliver about 2 GW for about 4 hours or so no good at all for long term storage, or long term excess.

    Quite agree electrolysis to hydrogen is one option, but hydrogen is a quite useless vehicle fuel due to the inability to get enough of the stuff into a vehicle.

    Much better to use ammonia, which is not, as ill informed people suppose, any more dangerous to transport than petrol, and can be readily used in existing engines, and you can get enough of the stuff into vehicles.

    Batteries are of course another option and twice as efficient as either hudrogen or ammonia, but don’t yet exist with sufficient range or cheapness, and have huge environmental impacts – like where are you going to get all the lithium from?

    Much better to go to electric trains, and electricity trams which can use the stuff directly, and travel at 70 mph (in 1935) with overhead pole pick up.

    Have you got any articles we can publish?

  3. I hope you do not mind but I have tried to post (not sure if I have been successful) the attached on the Claverton web site.

    It is a commentary on your article “Is wind reliable”

    Please feel free to rubbish what I say


    Denis Stephens
    Dennis –

    I’ve loaded this article into the file area ( I wish others would learn how to do this and help me out by the way)

    (You can look at all the wind files by going to LIBRARY / DOWNLOADING FILES and clicking on wind)

    I’ve then put the link as a comkment on the main article by David M



  4. It is a question of how to utilise fully the electricity generated by an intermittent and unpredictable supply…… generating hydrogen via water electrolysis is a very good way of storing energy for long periods of time…. it is a fuel that can be used as and when required, and allows the power industry the opportunity to make a clean transport fuel with surplus electricity at off peak times.

    See what Quentin Willson thinks, at the recent launch of ITM Power’s Hydrogen On Site Trial (HOST)….

    A year long trial with 21 commercial logisitics companies representing 7 sectors…. making a fuel where it is needed, at the point of use, so eliminating the carbon footprint of delivered fuel, the fuel production (if renewable energy used) and the carbon emissions of vehicles.

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