Two giant Vestas wind turbines in the UK collapsed within weeks of each other in an indication there may be a serial failure in Vestas turbines taking place.
THE firm has insisted there are no major problems with their structures. An executive from Vestas Wind Systems gave the reassurance after it emerged that one of its turbines had fallen in Scotland just weeks before the most recent incident near Caldbeck in Cumbria. They have launched investigations into the incidents. The global manufacturer has produced about 35,000 turbines since being formed in the 1970s.
Most recently, a 100ft steel turbine collapsed at J Stobart & Sons animal feed mill, Hesket Newmarket, on December 28. It had been helping to provide power to the mill for 19 years. A six-year-old Vestas V47 turbine toppled at Scottish Power’s Beinn an Tuirc windfarm at Kintyre on November 8. The 200ft mast bent in half and crumpled to the ground after being hit by a 50mph gust.
The Health and Safety Executive suggested precautionary measures are carried out.
In a November 19 press release,Vestas said the HSE has advised that,for Vestas V47 (660-kW) and V52 (850- kW) turbines,the “maximum speed pause” is adjusted from 25 meters per second to 15 m/s,and “auto reset parameters” reduced from maximum ten to maximum five (the number of times a turbine can re-start in a 24-hour period).
An investigation into the turbine collapse is on-going, Vestas said. Its technical and managerial teams were working closely with the HSE and others “in order to bring the matter to an early and considered conclusion. Until these investigations have been finalised,it is too early to make any conclusions,however,there is no early indications whatsoever that there is a serial inherent safety issue with this particular turbine class,” Vestas said.
The Danish turbine manufacturer noted that,as the HSE’s comments “merely provide precautionary guidance in the United Kingdom,we are under a duty to pass this guidance on to all our customers,so as to allow them to form their own judgement on an informed basis.”
President of Vestas Northern Europe,Klaus Steen Mortensen,told Platts: “the tower of the Scottish turbine under investigation bent over due to high wind speeds. We definitely believe it was a one-off and not a generic fault. We have many such turbines operating in high winds that have never failed.”
Mortensen said conclusions on why the tower failed should be available very soon. Vestas has installed over 2,100 V52-850 kW wind turbines world- wide.
Speaking from Denmark,Vestas’ Peter Wenzel Kruse, said: “Our inquiries are ongoing so I cannot give details on why these turbines have collapsed. They are two very different kinds of turbines.
“Investigations are not concluded but we believe the incidents are one-offs. It is the first time we have had these experiences. We want to know why.”
Following the turbine collapse in Scotland, Vestas president Klaus Steen Mortensen said in a press statement on November 19: “Until these investigations have been finalised, it is too early to make any conclusions, however, there are no early indications whatsoever that there is a serial inherent safety issue with this particular turbine class.”
The Health and Safety Executive has confirmed that it is awaiting the results of the manufacturer’s inquiries on both incidents before deciding whether to launch its own full-scale investigation.
The collapse in Cumbria prompted safety fears to be raised by anti-windfarm campaigners.
CUMBRIA’S oldest wind turbine was the second to collapse and an inquiry has been launched into what may be the first such incident in the 29-year history of harnessing wind energy in the UK.
The Health and Safety Executive has been notified of the incident, which has prompted safety fears from Cumbrian anti-windfarm campaigners.
Investigations are under way to determine what caused the 100-ft steel structure near Hesket Newmarket to crash to the ground. The British Wind Energy Association, which represents 98 per cent of UK wind energy firms, will be directly involved and has pledged to act on any potential issues arising.
The turbine, thought to weigh around 11 tonnes, has been helping to produce energy to power J Stobart & Sons animal feed mill at Newlands for the last 19 years.
When it was installed it was only the second privately-owned wind turbine in the country. But it collapsed, narrowly missing a country road, at around 11.30am last Friday (DEC 28) while the plant was operating. No-one was hurt.
J Stobart & Sons, which has been operating for around 40 years, notified the HSE. The HSE is waiting for further details before deciding whether a full investigation needs to be carried out. Peter Stobart, one of the company’s directors, has confirmed that investigations will be carried out by the contractor employed to maintain the turbine, as well as insurers.
Installing the turbine was an innovative development when it was passed around 20 years ago.
Mr Stobart said: “It is a sad end to this machine. It has been a great success in terms of what it generated. It produced an estimated 4.5 million units of electricity. It is unfortunate that it has met such a sad and sudden end.”
He added: “All those years ago it was a very innovative thing to do. It was certainly the first in the county and only the second in the country, privately-owned, that is.
“It was ahead of its time. We did it purely because we saw energy costs going up and, apart from what happened on Friday, it has been a tremendous success in what it has generated and the costs saved.”
Commenting on Friday’s incident, he added: “People said they heard something but no-one saw it come down.”
The collapse is likely to spark interest among windfarm campaigners and the renewable energy industry. Many turbines have a lifespan of 25 years.
Ruth Walsh, chairwoman of Communities Opposing Lamonby Turbines, said: “The turbine was only 19 years old and they are supposed to have a 25-year life. It fell near a road when fortunately no-one was driving or walking along it.
“It was windy but only averagely so for these parts. We’ve had much worse.
“We are extremely worried about this as it raises big questions about turbine safety, especially as the ones proposed for our village are over 100 metres tall. This must give councillors something to think about when they are considering future proposals.”
The British Wind Energy Association says last Friday’s collapse appears to be the first in its 29-year history where foul play is not involved.
The BWEA is working with the manufacturer, a long-serving member of the group, to try and understand why the turbine fell.
The organisation is waiting to discover the cause of a turbine collapse in Scotland, but foul play was believed to be involved.
Graeme Cooper, health and safety technical officer with the BWEA, said: “Turbine failure is very rare so this is very important to us and we will be directly involved.
“This is the first of these specific kind of incident we are aware of and there are over 2,000 installed turbines in the UK.”
He added: “The design life of a turbine is about 20 years and this had been up for 19, so it was pretty much at the end of its design life. It was also a very small turbine with a very early design.
“Taking the 19 years into account it has been doing a very good job and we have to remember that the industry and designs have changed drastically, there have been 19 years of developments and improvements made.
“If there is any learning from this incident here it will be taken away and if there are any ways of improving turbine design as a result of this then we will do it.”
15 January 2008
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