Wednesday, 28 December 2011

Risky round up...

Somehow, I didn't think my post dated Tuesday December 13th would be the last word on safety!

First, it appears I need to correct a couple of 'factual inaccuracies'. On Thursday, 8th December 2011, I posted a piece entitled "Going over Like Dominioes'. In that post I reported that the turbine that came down in Coldingham was as a result of a catastrophic failure. This was how the accident had been widely reported and there was therefore no obvious need to doubt the reporting. It now appears that in actual fact, this turbine was deliberately bought down as a direct result of the turbine's brakes having failed - it was deemed the safest thing to do.

Next, In the same post I reported that the Coldingham turbine was the first catastrophic structural failure to occur in Scotland - well, it wasn't. In 2008, a Vestas turbine on Kintyre collapsed. It is entirely possible there have been more catastrophic failures - reports are sometimes difficult to find - and you tend to miss them if you blink.

On to risk assessments. On Tuesday Decemeber 13th, I made mention of a risk assessment that was carried out in support of a wind turbine application in Northamptonshire. I was particularly interested in this as I wanted to understand the rigour of the approach taken since Environmental Statements for other applications make reference to this report. Well, after some particularly obtuse Googling, I found the assesment, in two halves. I have therefore stitched the two halves together and made the risk assessment available here and in the sidebar of the blog under Reference Documents.

After a cursory read of this document, there appear to be a number of serious flaws with it. First of all, in attempting to quantify the probability of various types of accidents, reference has been made to the statistics made available by the Caithness Windfarm Information Forum (page 23 and page 32 refer). Now, I have the upmost respect for the work of this group, but why weren't comprehensive industry data used as the basis for the probabilities? Accident data is compiled by Renewables UK - it's just not made public. The effect of using the Caithness group's data? Well, assuming the data the Caithness group publish is incomplete (and that is highly likely since they rely largely upon press reports to compile their tables), the probabilities are so badly skewed that they cannot in any way be relied upon. Essentially then, there is every possibility that the probabilities demonstrated in this document completely under-estimate the real-life risk.

Next, I had a quick look at the calculation used to predict the arc of possible ice throw (starting on page 17, and including Appendix 1). Initially, this looked quite promising. I have no issue with the general equation used to calculate the arc of probable ice throw (Appendix 1). Unfortunately, that's where the good news ends, since no account has been taken of the 'lift or lob' effects of the wind on a piece of dislodged ice. Such effects are acknowledged in a footnote at the bottom of page 17 - but then promptly brushed aside.

These two issues in themselves are I believe, sufficient to ensure that this document has no place in any reasonable Environmental Statement. Using out of date, incomplete statistics and over-simplified physics to demonstrate the apparent safety of wind turbines is not in my opinion a valid approach to performing a useful risk assessment. As such, any Environmental Statement that relies upon this document as supporting evidence has to be seriously open to question.

Should you come across references to this report in an Environmental Statement you really should question both the accuracy of the data, the validity of the conclusions and the apparent science used to reach them; this document has to rank alongside ETSU-R-97 as one of the most flawed pieces of writing you are ever likely to come across with regard to wind farms.