A little while back we covered a spate of turbine collapses across the UK – terrorising locals not used to the sky-falling in around them on a regular basis (see our post here). And we recently covered the terror being wrought in schoolyards in Scotland by collapsing fans and flying blades in this post.
We’ve dealt with the increasing numbers of turbine blades that routinely unshackle themselves in bids for airborne freedom, troublesome events, which the wind industry euphemistically calls “component liberation” (see our posts here and here and here and here).
While we thought for a while that these cases of random turbine collapse were just ‘unlucky’ aberrations, it seems that Newton’s predicted constant, gravity, has been working overtime – sending turbines crashing back to earth in frightening numbers – from Brazil – to Kansas – Pennsylvania – and everywhere in between.
Here are a few more tales of tumbling turbines suggesting that – for those unfortunates forced to live, work or go to school anywhere near these things – hard hats aren’t going to cut it: it’s a case of run for your lives.
100m Turbine collapse: Not bolts this time – weld failure in the main tower
17 December 2014
De Bilt reports on yet another serious turbine failure. This time the 100m structure folded at a weld line some 30m off the ground. This is of great concern.
Whereas most catastrophic failures are due to installation errors at the base bolts, this is a problem with the specification or execution of the construction of the monocoque structure – the main tower.
There’s a fundamental problem here. When steel is welded, the structure of the material either side of the joint, and the weld itself is different to the rolled steel sheet. This inevitably creates a location where stress gets concentrated more as the structure ages.
This is because the material at the joint is more prone to ‘work hardening’, a process which occurs, for example, when stresses are repeatedly applied and relaxed by the resonant motion of the structure in the wind.
Wind turbines are particularly prone to this because of the heavy weight on the top of the structure and the wind-exposed location they are placed in.
Work hardened steel becomes brittle, and brittle materials crack. Cracks are huge stress raisers and can propagate faster than the speed of sound during catastrophic failure. This is the cause sharp, loud whip-crack like noise you sometimes hear when something breaks – a miniature sonic boom.
You can see from the photo above that the crack has propagated right around the main tower and caused the catastrophic failure. You can see the aftermath in the photo below. Good job no-one was driving a tractor or walking a dog under this when it came down.
We can expect catastrophic failures such as this one to occur more frequently as the wind turbine fleet ages.
So what programme of inspections is in place to regularly inspect wind turbine towers for cracks resulting from work hardening of the weld joints?
I don’t know, because the industry is secretive about problems, but when did you last see inspectors with magnifying glasses spraying crack revealing dye penetrant on weld joints 20-100m off the ground up the side of a wind turbine?
Time for the government’s ‘Elf and Safety’ executive to step up and give a report on the state of wind industry oversight.
It’s not just Germans worrying about unscheduled turbine ‘decommissionings’, the Scots have their fair share of wind turbine worries, too.
And they keep repeating themselves, with the same turbines collapsing and throwing blades around the countryside more than once.
As Mr Bond’s nemesis, Goldfinger aptly observed: “Once is happenstance. Twice is coincidence. Three times it’s enemy action”.
Anger as turbine crashes to earth for second time
The Northern Times
19 December 2014
A PUBLICLY funded, £37,000 wind turbine sited next to a community hall in north-west Sutherland has crashed to the ground for a second time.
The tower of the 15-metre high turbine at remote Rhue Stoer Hall, north of Lochinver, snapped in two last Thursday, sending the gear box housing and blades tumbling to the ground. It is the second such structural failure in two years.
The turbine was reported to be “askew” and making a “funny noise” just prior to the crash.
Members of the Rhue Stoer Community Association, which runs the hall, were remaining tight lipped about the latest occurrence. But the incident has reignited concerns about siting small-scale wind turbines close to public buildings, particularly schools.
Stoer resident and turbine safety campaigner Dr Stephanie James has now renewed her call to Highland Council to take down the turbine at Stoer Primary School, and others.
She warned: “Highland Council is being negligent in maintaining that these turbines are safe when clearly they are not safe. It is an accident waiting to happen.”
Planning consent was granted in November 2010 to site a 6kw wind turbine on a rise to the south-east of Rhue Stoer Hall and 90 metres from the B869.
Opponents claimed the turbine would be visually intrusive and a noise nuisance.
But hall managers went ahead and erected the French made Eoltec Scirocco wind turbine in mid 2011, with funding from public sources. Just six months later, on Hogmanay 2012, one of the turbine blades flew off, landing several metres away from the tower. The remaining blade crashed to the ground later.
Engineers from the manufacturing firm travelled to Stoer and took away the mangled remains for investigation, the outcome of which is not known.
A heavier duty gearbox and blades was eventually fitted to the existing tower and the turbine began operating again in the middle of 2012.
But its failure was the precursor to concerns being raised over the safety of Highland Council’s programme to install small-scale Proven WT6000 turbines at schools at a cost of £25,000 each.
In February 2012, worried north councillors refused to sanction planning applications for two new turbines at schools in Inverness and Nairn.
Three months later the authority gave in to mounting pressure and shut down all 16 of its school turbines pending individual risk assessments by independent consultants.
Three of the turbines involved were at Sutherland schools – Dornoch Academy, Rosehall Primary and Stoer Primary.
But the order to turn the blades on again was given in November 2012 after the consultants concluded that the turbines operated safely in wind speeds up to 134mph. The latest incident involving the Rhue Stoer turbine happened between 8.50am and 9.05am last Thursday, in relatively moderate weather conditions but following a storm the day before.
Psychologist Dr James, who lives close to the hall, said she had become aware the turbine was not working properly that morning.
She said: “The turbine looked a bit askew and was making a funny noise. The top of the mast was leaning by about five to 10 degrees. Despite that I was quite astonished when, 10 minutes later, I saw it on the ground.”
Dr James wrote to Highland Council chief executive Steve Barron earlier this week informing him of the incident and once again flagged up her concern about the siting of micro turbines at schools – particularly Stoer.
She stated: “I request that you immediately lower the turbine at Stoer School until such time as you can satisfy the public that the likelihood of such a catastrophic occurrence happening at the school is nil. I consider it can only be a matter of time before a fatality occurs. This most recent incident simply compounds my concerns.”
Dr James has dismissed the risk assessment carried out by Highland Council on turbines at schools as “risible” and a paper exercise which did not take into account variables at individual sites.
She said: “The writing is clearly on the wall. These turbines are not built to withstand the strong winds we get in the north-west.” North anti-wind farm campaigner Brenda Herrick said: “The consultants’ report recommended ‘turbine siting safety zones’ consisting of a fall zone, a wider topple zone and a wider still ejection zone.
“This was ignored, presumably because there is not sufficient space, and it seems the council just hopes for the best.
“It should reconsider its practice of exposing children to danger and remove turbines from school playgrounds.
“I trust the Stoer Community Hall Association will not assume third time lucky and will now give up, in the interest of residents.”
North, West and Central Sutherland councillor George Farlow, who supported siting a turbine at Rhue Stoer hall, said: “I look forward to hearing the outcome of the investigation into this structural failure.
“A review of wind turbines at schools has already been carried out by Highland Council. I do not know of any other similar incident in the Highlands. I continue to support communities who wish to grow.”
Members of the Rhue Hall Community Association were reluctant to comment but said the group had already been in touch with the turbine supplier and would have a committee meeting to discuss the way forward.
A Highland Council spokesman said that the council would reply to Dr James in due course.
The Northern Times