Bishop Hill Identifiable decline
Jan 15, 2014 Energy: wind Readers will no doubt recall the study by Gordon Hughes, which suggested that wind farms are wearing out much more quickly than previously thought. This was the subject of a bit of to and fro at BH the other day, when Prof David Mackay, the chief scientist at DECC, appeared in the comments to dispute the findings. There were some further developments at around the same time, which I have been meaning to post since before Christmas.
At around the same time he appeared in the comments at BH, Prof Mackay published a more detailed rebuttal of Hughes at his own blog, which he said showed that Hughes' results were spurious. Hughes' model has parameters for the age-related performance of the wind farm, one for the windiness of the place in which it is located, and another to relate its performance to other windfarms. Mackay's case is that Hughes' model is non-identifiable, which means that the fit to the data is arbitrary: Hughes could, according to Mackay, explain the data say with a fast decline in performance and an increase or windiness, but could also do it with a slow decline in performance and a decrease in windiness. This point was disputed by Hughes.
The following day the Renewable Energy Foundation published some background, explaining that the two sides had in fact been discussing the issue since the original Hughes paper appeared in 2012. Hughes had apparently met with Mackay and had at that time apparently persuaded him that the model was in fact identifiable. Mackay had then shifted position somewhat, claiming only that the decline in performance was overstated (he suggested 2% per annum compared to Hughes' 5%). However, by May Mackay had apparently reverted to his earlier position, namely that Hughes' model was non-identifiable.
The REF's summary of the story to date ended with this strikingly robust statement:
Professor Mackay has made considerable efforts, first to persuade us to withdraw Professor Hughes’ paper, and now publicly, and on dubious grounds, to discredit work which is obviously original and draws attention to a previously undiscussed phenomenon, the decline in load factor over time, that was not acknowledged, for example, in the Department of Energy and Climate Change’s own levelised cost estimates for wind power. This is extraordinary behaviour for a Chief Scientific Advisor to government. Rather than shooting the messenger, Professor Mackay might more fruitfully be advising government on how best to ensure that consumer gets better value for their subsidy, and that we present a more economically compelling example of the low carbon economy to the developing world.
Reader Comments (59)
MacKay is a smart guy and his book was fairly realistic and sensible. As a scientist he is head and shoulders above the phil jones's and michael mann's. It seems to me that there is a definite issue here that needs to be analysed and he and Wilson need to get to the bottom of it. I see no problem with the two guys going toe to toe and debating it out with logic and data until the mist clears and they both see the answer. This is how science is done. It's not always pretty.
BTW - I remember MacKay from a physics summer school we both attended in Corsica in 1992 (he does not know me). He was wearing a T-shirt with the slogan "Bayesians probably do it better". It was funny at the time. If you're a probabilist. Well ... sort of.
MacKay is just trying to keep up with his peers by applying "hide the decline" to a new problem area for the climatocrats.
@ Richard Drake Jan 15, 2014 at 5:10 PM
If you go to DECC you will see that
AdvisOr
"As a scientist he is head and shoulders above the phil jones's and michael mann's."
So he's got no excuse for acting like he is, then?
"Ed Miliband thinks she's clever."
Cleverness is relative you know. Compared to Ed Miliband she probably is clever.
Entropic;
"Wind farms decline in efficiency at a rate between 2% and 5% per year.
On its own this is not particularly useful. How does it compare with the effect of ageing on other types of power generation?"
You forget the ease of maintenance/repair (and the cost) which will have a strong impact on keeping things running.
In an old fashioned turbine hall (think Battersea Power station) the overhead crane could lift out a turbine or generator, move it to the repair/maintenance area, slot a new one in and do the neccessary bearing changes etc in their own time in a workshop. Scheduled maintenance is easy. During low demand (at night) you can swap out the turbine or generator using the overhead gantry installed when the hall was built and have the new one running when we put on the kettle for our morning coffee
Now think about changing out a nacelle on a windfarm (on land or at sea). Maintenance is just going to be too difficult to do - even to the point of not being economically viable. Think weather, tides, distance, logistics, etc.
So it is easier to just abandon the broken one - it still earns a subsidy as part of the field.
NicL: "So it is easier to just abandon the broken one - it still earns a subsidy as part of the field."
Does it though? I thought that the subsidy was given per MWh, either as an above-market rate or as ROCs (or both).
NicL
I was hoping for comparable efficiency decline numbers for different types of power station. Can anyone in the electricity generation business help?
this quote from the REF answer, if true, is mind boggling to me -
"This technical debate aside, the key finding of Professor Hughes’ paper stands, namely that wind turbine performance declines over time, which is an original finding not before published. Indeed, as a result of the Hughes paper, Professor Mackay himself now accepts that there is such a decline. Furthermore, it must be noted that his own, lower, estimate of the rate of the decline is still economically significant."
am I reading/understanding this correctly ?
if this truly is "an original finding not before published" someone needs to answer for mismanagement of public funds.