Danish Wind Generation Load Factors 1990-2009

From a pointer from “Bernie” in comments at Bishop Hill’s web site, I took a look at the annual load factor for wind generation in Denmark based on data published at Wikipedia. I chose to do the analysis starting in 1990 as it appeared from the data that the first decade of wind power in Denmark was low–probably caused by the learning factor effect.

The probability distribution is shown here, along with the raw data from Wikipedia.  The mean over this 20 year period is about 21%.  The trend is generally upward, but there is variation represented in the probability distribution.



16 Responses to Danish Wind Generation Load Factors 1990-2009

  1. […] 4 on 2 Dec 2010: See a 20 year analysis of Wind Power Load factors for Denmark at https://rmschneider.wordpress.com/2010/12/02/danish-wind-generation-load-factors-1990-2009/ […]

  2. fujirobin says:

    Aren’t you getting a little hung up on load/capacity factors? It is surely possibly to design a wind turbine to yield a higher CF by going after the more frequent lower-speed winds and wasting the higher-speed winds, thereby down-rating the turbine. But energy being proportional to cube of windspeed means you’d end up with less energy. So they optimise for energy production rather than CF.

  3. rms says:

    I’m getting “hung up” becuase a) the load/capacity factors planned/assumed for a wind farm are not noted in any publication I’ve seen. When talking about the power output for wind farm, the “name-plate” capacity is quoted and then in the MSP they then go on to say how many homes that will power. My fear is that these numbers are 3-6 times over stated (at least). If the wind farm get’s 3-6 times less power than planned, then the economics get all wacked out of shape and the investors will lose. If that were private investors I’m not bothered so much. But increasingly in the UK it’s municipalities and the government making these investments.

    See the 457 MW quoted for the Viking Wind Farm field for Shetland, funded by borrowing by the local authority and some private investment from Scottish Southern and Electric (as I understand). As reported in the press at 457 MW output (before load factor), they will export “large quantities of power”.

    Things just don’t add up.

  4. rms says:

    That’s what it appears to me. But they use 100% when talking of how much power will be produced and what the export potential is.

    If the whole country of Denmark get’s 21% over the last 20 years, it makes me wonder.

    I’m seeking find out where the 45% figure can be justified. I’m told by SCDI that “Onshore windfarms on Shetland have been shown to have the largest load factor in the world.” I’m trying to find where this is measured or if just reported.

    I hope they aren’t using single point estimates in their business case and instead relying on probabilistic approaches. I’ve seen no evidence that they are doing this; which also makes we concerned for the viability of the investment. I’m not bother about private investment but a lot of public money is at risk here.

  5. fujirobin says:

    From http://www.bwea.com/ukwed/google.asp it appears that there is only one windfarm in the Shetlands and a handful in the Orkneys

    Using REF’s data from http://www.ref.org.uk/uk-renewable-energy-data we have:

    Burradale (Shetlands) 47-57%
    Westray 40.8%
    Spurness 23-33%
    Bu Farm 29-44%
    Holodyke ?
    Hammars Hill ?
    Burgar Hill 37-40%
    Thorfinn 39-40% (51%)
    Sigurd ?
    Northfield Burray 41-48%

    (range of CFs over the years) data is incomplete for some years and those with “?” must have a different name. All these are way higher than Denmarks. I guess the Shetlands and Orkneys are pretty windy ! Prima facie 45% looks reasonable.

    Looking at the effort Viking have put into surveying otters and the like, I’d guess they’ve done their homework on windspeeds!

  6. rms says:


    Thanks! I would expect a lot of wind up there and I’m glad its showing up in the statistics. I’m also sure they’ve done their home work on windspeeds.

    Have you run across any business case documents, e.g.
    : what is the capex and cash flow, esp. 80% probable figures
    : how much money funded by government?
    : how much power has to be produce at what revenue rate to give the government a return on investment?
    : what is the per kWH cost of the power?
    : etc.

  7. fujirobin says:

    Not for Viking but a smaller-scale Scottish plan here http://www.storasuibhist.com/wordpress/wp-content/uploads/2009/10/Loch-Carnan-Community-Wind-Farm-Business-Plan-2009.doc

    might help. I can’t find the financial forecasts but the plan should give you some idea.

    On their figures,
    Capex = £11.5 M
    Annual income = £2.9M (@ 48% LF)
    Anuual costs = ?

    but I think they came unstuck on the grid connection

    • fujirobin says:

      sorry – had another look – op costs are 350k (before interest?) and they downgrade the LF by 86% to cover outages.

      So that gives a net £2.1M annual contribution.

      Quite a lot depends on the deal agreed for electricity – the PPA. You’d need to see few actually agreements to know what is obtainable… but I guess that’s commercially sensitive.

  8. rms says:

    thanks. gives me some numbers to play with.

    Re “commercialy sensitive” … fully understand that; but when government money involved with financing and taking a stake, not sure it’s completely justifiable to keep this info hidden behind this wall. Just my two bits.

    Re downgrading the loadfactor … interesting. I get the impression from those I speak with on this topic that they believe load factor only a function of wind speed and how often it blows.

    As you surely know, there is a lot more that gets in the way of producing power (low wind, high wind, mechanical outage, no demand, etc.)

    Interesting (but not unexpected) that at first glance this business plan doesn’t present all this a probabilistic … As the investor, I’d want them to use Monte Carlo or something to show sensitivity of these basis items. I’d also insist on a risk assessment including the planned spend on mitigating those risks.

  9. fujirobin says:

    Another one for you http://webarchive.nationalarchives.gov.uk/+/http://www.berr.gov.uk/files/file41542.pdf

    This is North Hoyle – a real working windfarm with some stats.
    Capital cost = £81 M
    op costs 2.5M pa
    60K pa to Rhyl
    generating 180-190,000 MWH pa

    ignoring indexation/inflation and guessing at the £81M being financed by an 8% loan I get 25 year costs at £109M finance + £64M other
    Divide these into 4.5M MWh and I get 3.84p/kWh

    The following year’s file had opcosts at 2.8 M, so reworking or that I get 4p.

    If you knock off the £10M BERR capital grant I get 3.7p

    Crude I know – but what have I missed?

  10. rms says:

    I must be thick. Where do you get the “4.5 M MWH” figure that you divide into? What’s that?

    I’m going to carve out some time on this over the next couple of days (today consumed with other work).

  11. fujirobin says:

    180,000 MWh x 25 years = 4,500,000 MWh

    the 180,000MWh is from REF’s analysis of OFGEM data (low-end figure)

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