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The Click Green article doesn't bother to link to REF, but the source is here, with this interesting introduction:

Low Wind Power Output 2010

In today's Times (02.02.11) it is reported that Scottish and Southern Energy (SSE) has published data confirming that its wind turbine fleet has reported a 20% reduction in energy generation in the last year. SSE is said to have released this data in response to requests from concerned shareholders.1

This is consistent with data examined by Renewable Energy Foundation at the request of the Sunday Telegraph, which resulted in a report by Andrew Gilligan to the effect that the UK wind fleet load factor in the year October 2009 to September 2010 was very low in comparison to previous years.2

"Concerned shareholders" and Andrew Gilligan of the Telegraph only have to ask...

REF says it derives its 23.5% number from Eirgrid (no comment on the extremely narrow scale used to provide a dramatic graph - well, that's a comment...):

A footnote refers to:  Eirgrid (Jonathan O'Sullivan), "Facilitating the Transition to a More Competitive, Sustainable, and Low Carbon Electricity Future". Presentation to the Irish Renewable Energy Summit, 20th January 2011, Dundalk.

That presentation isn't online. The Summit has a site where Jon O'Sullivan is mentioned as doing a presentation with that title; but in fact the Speakers' Panel doesn't contain Jon O'Sullivan, and in the PDF brochure the presentation is down to Dermot Byrne, also of Eirgrid. But let's suppose the presentation was done for the conference (where it was followed by REF boss John Constable on wind variability).

Eirgrid offers system data on its site, with a page for Wind Generation. You can download generation stats (at quarter-hour intervals) for the dates you choose. But you don't get (or I didn't find) electricity delivered in MW/h.

As to capacity, the Wikipedia article is weird, since its own reference states:

Irish Wind Energy Association - Wind Energy in Ireland

The current* grid connected and operational installed wind capacity on the island of Ireland is 1746.7 Megawatts (MW) which will on average generate 4,743,339 Megawatt hours (MWh) in a year given a 31% load**or capacity factor.

... *Figures correct on 19/07/10.

According to a report (pdf) by the Sustainable Energy Authority of Ireland and Eirgrid, total island capacity (NI included) in 2011 is 2,163 MW.

That report is well worth reading in itself (it's quoted in the Wikipedia article re wind lowering costs in such a way as to cover FIT costs). But it doesn't give 2010 capacity. So the 23.5% still needs more digging to be validated.

by afew (afew(a in a circle)eurotrib_dot_com) on Thu Jun 23rd, 2011 at 01:25:33 PM EST
[ Parent ]
Coincidentally I've been looking at the same site and managed to crash Excel by downloading a years data and trying to graph it!  I suspect most of the confusion is because the situation - both installed base and weather - is changing all the time and the data is therefore very variable.

Index of Frank's Diaries
by Frank Schnittger (mail Frankschnittger at hot male dotty communists) on Thu Jun 23rd, 2011 at 01:37:15 PM EST
[ Parent ]
I got the 2010 data into Excel - but I don't think it helps to get to the capacity factor.
by afew (afew(a in a circle)eurotrib_dot_com) on Thu Jun 23rd, 2011 at 02:29:20 PM EST
[ Parent ]
I was more trying to establish was there a secular downward trend which might validate the very low 23% Capacity factor for 2010, and whether the trend for 2011 was upwards of that.

Index of Frank's Diaries
by Frank Schnittger (mail Frankschnittger at hot male dotty communists) on Thu Jun 23rd, 2011 at 02:38:43 PM EST
[ Parent ]
Can you make monthly sums? Here you can find end-of-month installed power capacity data from April 2010, monthly capacity factors can be approximated with less uncertainty than annual ones.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Thu Jun 23rd, 2011 at 03:17:00 PM EST
[ Parent ]
Well, it's not MW/h. And the sum is huge. The mean over the month is more like it. So, for April 2010, with an installed capacity of 1308 MW, average production was 239 MW, which (with a few ifs) would correspond to a capacity factor of 18.3%.
by afew (afew(a in a circle)eurotrib_dot_com) on Thu Jun 23rd, 2011 at 04:13:51 PM EST
[ Parent ]
This compares monthly average generation (from Eirgrid data) with capacity as per the pdf you link to.

The colour schemes has nothing to do with the Irish flag, just my fear we may be comparing apples with oranges.

by afew (afew(a in a circle)eurotrib_dot_com) on Thu Jun 23rd, 2011 at 05:37:43 PM EST
[ Parent ]
Excellent work!  I don't see any sign of declining output there - I suspect the production trend line would be slightly upward.  My visual guess would be the average capacity factor is about 25% - higher than that given for 2010, but still below the average of previous years.  Can you confirm?

Index of Frank's Diaries
by Frank Schnittger (mail Frankschnittger at hot male dotty communists) on Thu Jun 23rd, 2011 at 06:24:35 PM EST
[ Parent ]
IF these are the relevant generation figures to the capacity figures, the percentage varies from 14.6% (June 2010) to 35.6% (Feb 2011), with an average of 23% and a rising trend.

But I'll try to get a longer view if I have time.

by afew (afew(a in a circle)eurotrib_dot_com) on Fri Jun 24th, 2011 at 04:32:40 AM EST
[ Parent ]
The wind generation page at Eirgrid seems currently unobtainable.
by afew (afew(a in a circle)eurotrib_dot_com) on Fri Jun 24th, 2011 at 08:56:21 AM EST
[ Parent ]
Probably storm damage - it's pissing rain here at the mo!

Index of Frank's Diaries
by Frank Schnittger (mail Frankschnittger at hot male dotty communists) on Fri Jun 24th, 2011 at 08:59:06 AM EST
[ Parent ]
no comment on the extremely narrow scale used to provide a dramatic graph

That isn't even the worst visual spin in it. It's the background image. Look at that subconscious suggestion of a trend.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Jun 23rd, 2011 at 02:05:11 PM EST
[ Parent ]
Right.
by afew (afew(a in a circle)eurotrib_dot_com) on Thu Jun 23rd, 2011 at 02:29:38 PM EST
[ Parent ]
There is nothing inherently wrong with a non-zero baseline. The background graphic, any background graphic, is "chartjunk" and shouldn't be used.
by jam on Fri Jun 24th, 2011 at 03:46:37 PM EST
[ Parent ]

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