Degradation Update, part 2

John Harrison was the first person (at least in public) to notice the year-to-year degradation of the output of Ontario wind turbines.  Then I followed up with Denmark and Mars Hill, and Paul-Frederick Back chimed in with more Denmark.  While our numbers vary, and none of us is completely happy with the accuracy of our results, there’s little doubt remaining that the efficiency of a wind turbine decreases, sometimes fairly dramatically, over time.

John’s latest effort is another look at Ontario, now with another year’s data.  His new numbers show a Capacity Factor decline averaging 1.1% per year, down from his earlier ~2%.  His summary graph:

Note the dashed line at the top.  It shows what Algonquin’s public projection is for the Amherst Island project.  Obviously, that project would be unique if it even came close.

His second major point was that Capacity Factors were increasing with newer turbines.  The newer turbines are sometimes called “high efficiency” but that is a misnomer.  The increase is due to larger diameters and swept areas being able to get more energy out of slower winds (and less out of higher winds, which don’t occur so often).  The actual efficiency of doing so at any particular wind speed hasn’t changed.  I also covered this in my maturity posting, and John’s work is consistent with what I found.

3 thoughts on “Degradation Update, part 2”

  1. I recently received this link

    Performance of UK and Danish Wind Projects.
    (By Gordon Hughes of Renewable Energy Foundation)

    http://www.ref.org.uk/attachments/article/280/ref.hughes.19.12.12.pdf

    I believe the take away mirrors your own – degradation in UK greater than Denmark but still significant.

    In the UK study: There is one take away that matches my own theory…

    The decline in performance with age is considerably greater when capacity weights are used. This implies that the performance of large wind farms declines more rapidly than that of smaller ones.

    My own theory is that larger wind farms are designed with turbines too close to each other and turbulence from one to another is an overarching factor. It would be interesting to compare UK windfarm designs to DK designs.

  2. Thanks for the input. I’d agree that large wind projects tend to be too compact. Part of that is just trying to maximize profit, but I wonder how much is due to overzealous subsidies. Ontario, with lots of land area, tends to have large projects, many of which are too closely packed. They also have a particularly rich subsidy, much like the UK. P.S. I just now posted on Hughes.

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