Tuesday
Dec102013
by 
Bishop Hill
Bishop Hill More windmill deterioration
Dec 10, 2013 DECC Energy: wind 
David Mackay has left a comment on the earlier thread, saying that in fact he maintains that Gordon Hughes' estimates of windfarm deterioration are incorrect.
Christopher Booker did not check his facts: Booker asserts that "David MacKay ... could not dispute [Hughes's] findings", but this is poppycock. You can find a technical report I wrote, pointing out a significant flaw in Hughes's analysis here or here. Another paper is about to come out in a peer-reviewed journal, by Iain Staffell and Richard Green, which does the analysis properly, combining wind data with weather data. There is a decline in wind farm output, but it is much smaller than Hughes asserted.
As Guido would say: "Developing".
Reader Comments (24)
I don't suppose the models/methods used take account of those wind turbines that stop working altogether, of which there seems to be an increasing proportion? Add a few zeros into the load factor stats and the results might be somewhat different...
exquisite mechanical constructions in saline stormy conditions never work well do they.
In fact, where is the experience book ? (link, books, reports, www..)
what no experience book?
lol
mickey mouse professionalism
Not sure David MacKay is making a good counter argument to Hughes in that somewhat opaque reference.
For example, he cocludes
" The raw data show that even 15-year old farms have actual load factors of about 24% +/- 7%. " - is this one farm, many farms?
It is a bit like saying there are smokers that even live into their nineties. Not a very useful statement and it doesn't negate the fact that smoking seriously harms you!
Nice to read a tacit acceptance that 15 years is old age for a modern windmill. We have a local one that is over 300 years old and still functional - progress, eh..?
Yeah, I agree with jamesp.
When they show us the numbers, it will be something like "megawatts produced per active windmill," while ignoring the more-important "total power produced by the entire wind farm over time."
Don't you get it? Anything that is not supportive of The Great Green Con (tm) is of course incorrect!
They have peer reviewed papers to back them up of course!
Mailman
Ptw (Dec 10, 2013 at 1:27 PM): the experience book does exist; it is just that it does not tell them what they want it to say. Every mariner worth his salt (pun intended) will tell you that the sea is a very hostile place; every part of every ship has to be cleaned, coated, greased, polished, washed, dried, checked, renewed, coated, cleaned, dusted, chipped, coated in an almost continuous process. Ships have crews for this, and have the added benefit of occasionally being in quiet waters where this may be done. Off-shore daffymills, however – by the owner’s choice – are located in areas that have the least probability of being quiet; they also have no permanent crew for maintenance, any maintenance personnel having to undergo the extremely hazardous process of boarding the daffymill from a vessel alongside, often in extremely hostile sea conditions. This leads to the rich irony that the time when the daffymill is most likely to require a maintenance crew is when it is not possible to get a maintenance crew onto it.
The Bismarck broke its own radar the first time it fired its guns in anger. After that it went into a bit of a decline.
Rad Rod: Of course, the 'Experience Book' has to read from back to front.... ;-)
The two Abstracts given by the "here and here" by David Mackay are one and the same. Both dated 28/5/13.
Is he trying to pull the wool over our eyes, or is it that he thinks that two references are better than one?
I am old enough to remember the phrase 'Bullshit baffles Brains'
[BH adds: I think he's just giving alternative sources]
"the actual load factors of 10-year-old farms are about 24% +/- 7%"
How many are 17 and how many are 31%? And what did they start out as?
michael hart
Ha ha, bloody hell can you imagine what a menace it would be if a windmill could do 30 knots and carried 15" guns.
p.s. Graf Spee had similar problems.
The average capacity factor of UK wind farms over the last 13 years is 27.0%. The best year achieved 29.4%, the worst year achieved 21.5%.
For the individual countries the figures are:
England 24.7%
Wales: 25.3%
Scotland: 27.9%
NI: 31.6%
Phillip - are those for onshore sites only? SSE's 2012 Griffin scheme (68 x Siemens 2.3MW prayer wheels) situated on a plateau 400-500m above sea level only managed 14% in its first year of operation. Apparently now managing 18% the last I heard. I did tell them at the public inquiry that the developers' claimed 25-30% was way too optimistic for Highland Perthshire, which is not synonymous with wind like the west or east coast, but the Reporter chose to believe the developer for some reason.
lapogus: I believe it includes offshore. See here
Reading Prof MacKay's paper - if I understood it correctly - he has used the same raw data as Prof Hughes.
The key seems to be Hughes' use of a "non-identifiable" model:
<< The study by [Hughes, 2012] modelled a large number of energy-production measurements
from 3000 onshore turbines, in terms of three parameterized functions: an
age-performance function, which describes how the performance of a typical windfarm
declines with its age; a wind-farm-dependent parameter describing how each
windfarm compares to its peers; and a time-dependent parameter that captures national
wind conditions as a function of time. The modelling method of Hughes is
based on an underlying statistical model that is non-identifiable: the underlying model
can fit the data in an infinite number of ways, by adjusting rising or falling trends in
two of the three parametric functions to compensate for any choice of rising or falling
trend in the third. Thus the underlying model could fit the data with a steeply dropping
age-performance function, a steeply rising trend in national wind conditions,
and a steep downward trend in the effectiveness of wind farms as a function of their
commissioning date (three features seen in Hughes’s fits). But all these trends are
arbitrary, in the sense that the same underlying model could fit the data exactly as
well, for example, by a less steep age-performance function, a flat trend (long-term)
in national wind conditions, and a flat trend in the effectiveness of wind farms as a
function of their commissioning date. >>
Apparently MacKay discussed it with him to try and get a better understanding and they did clarify certain points which left MacKay to conclude:
" So my overall conclusion remains: the model used by Hughes [2012]
either is non-identifiable and therefore produces spurious results; or is identifiable
thanks to minor details involving different granularities of representation of time,
or other arbitrary constraints, and produces results that depend spuriously on those
minor details or constraints."
I cannot judge the merits of MacKay's comments. Has anyone seen a response from Hughes or has someone else with the requisite skills carried out a review?
Whatever the outcome of the technical debate, it does look as if Booker was mistaken.
Radical Rodent
Thanks for that.
But was the experience book used in developing the presented business case?
Or did someone just , you know, put something together. Probably with nice photoshopped pictures, multicultis and young wimmin with piano smiles hanging over each other's shoulder etc.
Or did "dave" skipped business cases and just decided for a policy , based on -cough- hot air, wind ??
ptw:
No.
Yes.
Well, what do you think?
" Another paper is about to come out in a peer-reviewed journal, by Iain Staffell and Richard Green, which does the analysis properly, combining wind data with weather data. "
Since when did wind data need combining with weather data?
Am I missing something?
So.....There is a strong decline....As the figures suggest. But some of it is due to a decline in wind speeds year on year, not all necessarily due to a decline in the equipment?
...Well that's reassuring then isn't it. Not only is the equipment more crap than we thought, but the wind is more intermittent than we thought too.
Hughes uses capacity weighting, which is not necessarily a small change to weighting. He also proposes that smaller wind farms may be better than large ones, as relative to each other the large ones lose capacity quicker.
It's interesting but also technical. The presentation of actual results by McKay is good though so maybe that's the place to focus.
I was wondering if there is a diesel-equivalent analysis, as in how much diesel would be needed to produce the same actual resulting energy because in the end that's the point. And also does capacity include times when backup is used to heat turbines or other related things like that.
Another factor not even taken into account, is the decline (over time) of actual wind around large wind farms. This was the subject of a learned paper reviewed a few months ago in my 'trade' journal (Professional Engineering), produced by no less a worthy than the Emiritus Professor of Physics at Harvard University in the States (who's name escapes me)...
The gist of the paper was the existence of the well-known feature known as wind 'shadow' - i.e. the reduction of wind towards the 'back' of a multiple installation - but which eventually leads to a decline in the amount of observed wind in the region of a large wind farm.
Its worse than we thought, folks...
Gordon Hughes actually showed a Mackay-style analysis in Figure 8, on page 24 and noted:
"Thus, a naïve analysis might conclude that there is nothing to investigate. However, as will be explained below, the distributions mask crucial differences between the performance of wind farms as they age because they do not control for the differences in location and wind availability over time."
Mackay's analysis has the caveat "(unless the weather has systematically drifted with time)" Which is, of course, what Hughes' analysis should take care of.
The bit of (one location) daily windrun data, that I have, shows a quite systematic increase in annual windrun-cubed over the period 1998 to 2008 (at about 9% per year) before falling back in 2009,10 and 11.
So Mackay's analysis might well be misleading.