By Christopher Hopson in London | Recharge | 28 October 2016 Updated 31 October 2016 | www.rechargenews.com
On 28 August, firefighters were called to a wind turbine fire in Isselburg, northwest Germany, but upon arrival discovered they did not have equipment tall enough to put out the flames. They could only watch as the NEG Micon turbine was consumed and the burning blades fell to the ground.
A month earlier, a turbine fire in India became an internet sensation after video (below) emerged showing a burning blade tip creating rapid spirals of black smoke. And in May, firefighters in Lubbock, Texas, watched helplessly as a turbine burned itself out, occasionally putting out small grass fires from falling debris.
When a wind turbine catches fire, it is almost always damaged beyond repair because it is so hard to extinguish. A fire and the knock-on downtime will cost a project owner an average of $4.5m per incident. It is a growing problem that costs the industry around $225m a year.
And it is not just money that is lost. In October 2013, a fire broke out inside a Vestas V66 in the Netherlands as four contractors carried out routine maintenance. Two escaped, but two – a 19-year-old and a 21-year-old – found themselves penned in by flames atop the nacelle. One jumped to his death to escape the inferno, the other’s burned body was later found atop the charred nacelle. Authorities are still investigating the incident.
“While the vast majority of renewable energy losses escape the attention of the international media, it seems that every few weeks a turbine fire makes the headlines,” says Jatin Sharma, head of business development at renewables insurer GCube.
“For owners, operators and insurers of wind farms, the thought of seeing a multi-million-dollar asset go up in flames is already a sobering one. For the incident to subsequently be broadcast around the world is the stuff of nightmares.”
According to GCube, there are roughly 50 turbine fires every year —one for every 6,000 machines – and the problem is growing and getting more expensive.
“The cost of fires is actually increasing compared to five years ago, mainly due to the arrival of larger turbines,” Sharma tells Recharge.
Vestas, for one, is taking the problem extremely seriously, treating fire prevention as a critical and integral part of its design and development process (see panel below).
The world’s top turbine maker believes the wind industry would benefit from greater consistency in fire prevention standards – adopting a more unified approach with defined quality expectations being applied across the industry.
“We would like to see increasing collaboration among OEMs, developers, independent service providers and certification bodies within fire prevention,” a Vestas spokesman tells Recharge.
Sharma adds: “Faced with this increased scrutiny [from negative headlines] and the long-term financial impact of a total turbine loss, we need to address the causes and consequences of turbine fires and, as a community, recognise that it affects each company in the industry.
“We cannot allow a handful of torched assets to become a symbol of our inability to work together.”
Researcher Anne Dederichs at Sweden’s SP Technical Research Institute, says: “There is virtually no research in this area, and no rules or recommendations for fire safety design of wind turbines exists, which is surprising, given its importance.”
So what is causing these fires and can they be prevented?
“The way we look at turbines is that they are effectively a big electrical and mechanical system, so there are two main causes of fire within them,” says Philip Rodger, principal scientific adviser at Bureau Veritas UK, which investigates the cause of fires on behalf of project owners.
“What you find is that the primary causes are electrical faults and failures, due to having a big rotating system. Fires can be caused due to damage or degradation, or in some cases a failure of the lubrication system.”
Rodger says a significant number of fires are due to a combination of high-speed winds and a failure of the turbine’s braking system, resulting in the rotor spinning out of control and causing internal frictions that create sparks, which ignite lubrication oil, plastics or electrical wires.
After the nacelle, the second most likely place for a fire to occur is in the control cabinet at the base of the tower, which contains a large proportion of the electrical monitoring equipment.
Operating turbines in extreme temperatures, outside their normal design parameters, has also been recorded as being a significant contributor to fires. For instance, problems arise when narrow temperature thresholds are exceeded for cables, transformers, nacelle components and the control cabinet.
“The causes of fires are rarely down to inherent design faults,” says Sharma. “It is more usually some piece of equipment which has been changed or been adapted that causes an issue.”
Having said that, he adds: “In some cases you can associate turbine fires with a particular new model of turbine, or with a batch issue from a sub-supplier.
“There are categories of turbines we will not insure because that machine has had so many incidents.”
He reveals that GCube has actually sought legal advice as it knows of a couple of turbine models that are particularly prone to fires. “Unfortunately the industry is not ready to hear that because it is libellous, embarrassing, and of course dangerous,” he says.
While there are some “anecdotal examples” of turbine fires being more prevalent in older machines – the recent German fire was in a turbine commissioned in 2001 – “we don’t have enough research to demonstrate if that is true”, says Sharma.
Another concern is insufficient or incorrect maintenance checks.
Rodger, who believes developers are becoming more aware of the issues, says the industry needs to look at making improvements in its initial fire risk assessments, by identifying hazards and taking actions on specific warning signs.
“We have found those carrying out remote monitoring of turbines who have access to things like heat and temperature logs, particularly for mechanical and bearing systems, don’t always understand the signs that there could be a potential problem,” adds Rodger.
Sharma points to an increasing emphasis by asset managers on reducing the levelised cost of electricity by cutting O&M expenses as being a root cause of a growing number of incidents.
“We are looking at an ever smaller number of staff who can get to turbines once faults are detected. I understand the need to reduce industry costs, but it’s a question of just how thinly you can spread people across different wind sites.”
However, the industry is adamant that the highly emotive images of catastrophic fires paint a false picture of the seriousness of the issue. “In relative terms the number of fires in the wind industry is not that significant,” says Chris Streatfeild, RenewableUK’s director of health & safety.
“For instance, we have worked in the UK with [government agency] the Health & Safety Executive, and they have assessed our risk profile, which is certainly no more significant than any other industry, particularly compared to oil and gas, [as] we don’t have the hydrocarbon risk profile.
“As long as we are producing energy, there will be electrical and mechanical sources of ignition, so the risk will always be there.”
URL to article: https://www.wind-watch.org/news/2016/11/01/turbine-fires-a-burning-issue-for-the-industry/