The turbine fire at Scroby Sands offshore wind installation off the Norfolk coast, "was first reported to HM Coastguard at about 10:50 BST" – BBC | Image by Emily Metcalfe
Yesterday’s fire in the nacelle of one of RWE’s Scroby Sands offshore wind turbines along the Norfolk coast prompted me to take another look at the fire risks of industrial wind turbines.
The wind farm operator confirmed its staff were safe and there were no injuries.
By Reemul Balla • Tuesday 15 August 2023 22:02, UK • Sky News
An investigation is under way after a fire on an offshore wind turbine.
A plume of thick black smoke could be seen billowing from one of the towers at the Scroby Sands wind farm on Tuesday morning off the coast of Great Yarmouth in Norfolk.
The alarm was raised around 10.50am and all staff at the North Sea site were accounted for after an evacuation, the coastguard said in a statement.
Pic: Oliv3r Drone Photography
RWE, the operator of the wind farm which is 1.5 miles off the coast, said the workers were safe and there were no injuries.
The German company stated it was the turbine nacelle - the enclosure at the top of the tower which houses the generating components - that had been alight following an incident.
A spokesperson for the operator said the blaze had "extinguished itself" after a short time, admitting it was "incredibly rare" for a turbine to catch fire.
RWE advised people to "keep away" from the area as the cause of the blaze was assessed.
It added: "Emergency services were contacted immediately and the coastguard made aware.
"They are monitoring the area and advising on a potential 500-metre restriction zone being enforced around the affected turbine."
Pic:Oliv3r Drone Photography
RWE said the 30 turbines at Scroby Sands have an installed capacity of 60 megawatts and can power over 48,000 households.
It is interesting to note from RWE’s 3 March 2022 press release that their “60 megawatts (MW) Scroby Sands Offshore Wind Farm was one of the first of a group of projects to be built in the UK, and all in coastal locations with relatively shallow waters close to shore. Scroby Sands was built on a prehistoric sandbank and, because of natural changes in the marine environment and coastal erosion, this has risen over time effectively isolating four turbines from being accessed by service vessels.” [Bold mine.]
How would the isolation of four turbines in the naturally changing marine environment in the North Sea impact upon fire and rescue services?
A whopping 90% or more of wind turbine fires originate in the nacelle. The nacelle contains the gear box, the generator, the controller, the low- and high-speed shafts, and the brake—and it (the nacelle) sits atop the tower (the part that supports the structure of the turbine and the blades). The ways that these fires are typically ignited are:
A lightning strike (just think about how far these lightning rods are off of the ground / up in the air)
Electrical malfunction / mechanical failure
Maintenance activities (which is when personnel are present and would be at risk)
What happens when a wind turbine fire does occur?
Approximately 90% of wind turbine fires result in significant damage to or a total loss of the wind turbine, as well as significant downtime and thus other economic losses. This is because the typical response is simply to wait for the fire to burn out. Further, burning materials that fall to the ground or which are blown by the wind can create a significant risk of extending the fire—and thus damage and loss—to the ground and/or surrounding property.
The above-described disastrous loss(es) can easily and cost-effectively be avoided by employing appropriate fire suppression methods, addressed in more detail below.
What can be done to prevent a nacelle/wind turbine fire in the first place?
When addressing fire protection for wind turbines (prevention as well as suppression), the best practices include both passive and active fire protection measures.
Passive fire protection is pretty much what the term “passive” implies, i.e., it is fire protection which, once implemented, does not require active action. Some examples of passive fire protection of wind turbines are:
Choosing noncombustible materials during construction (in this case, specifically, the nacelle)
Selecting/using noncombustible hydraulic and lubrication oils
Compartmentalizing the nacelle area
Installing lightning protection systems
Installing systems to monitor the conditions of components/equipment
So what are the best, most effective systems to use once a fire has been ignited in a wind turbine?
No matter the extent of passive fire protection measures which are employed, one can never assume that a fire will not occur. And once a fire does occur, immediate measures must be taken, particularly before a very small, undetected, and remote fire evolves into one which significantly damages or totally destroys a wind turbine.
In the case of a wind turbine fire (as with many other industrial fires), active fire protection involves:
Instant fire detection
Instant triggering of fire alarm systems
Quick-acting fire suppression systems
The most widely used and most effective fire suppression systems in wind turbines are aerosol systems. A connected smoke/heat detector sends a signal to the aerosol system which immediately activates a discharge of the fire extinguishing agent. The fire is extinguished almost as quickly as it started, minimizing both the risk of extensive property loss, as well as potential loss of life.
All wind turbines should be equipped with an intelligent fire detection and aerosol suppression system. The cost of having such a system is minimal; yet, in the event of a fire, the cost of not having such a system would most likely be catastrophic.
Therefore, a proactive approach to wind turbine fire protection is essential. The simple, non-obtrusive installation of a proven detection and suppression system is a must for these confined, remote, and costly assets.
Given that toxic microplastic fragments would already be shedding from the turbine blades into the surrounding marine and onshore environment, what happens when the blades catch fire?
Poly- and perfluoroalkyl substances (PFAS) are chemicals that are man-made. They do not occur naturally in the environment. Examples of PFAS are GenX, PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonates).
Teflon is the best known PFAS variant, used, among other things, as the non-stick coating of frying pans. However, PFAS substances are very toxic. They are blamed for a large number of serious health problems such as liver damage, testicular and kidney cancer, thyroid problems…
The problem is that they spread very easily in the environment. For example, PFAS remains were found on the Tibetan highlands and in Antarctica. They only disappear very slowly from the environment. In other words, they accumulate slowly and can accumulate to levels that are harmful to living things.
Information from a 2020 study does not bode well in terms of what happens to PFAS when interacting with fire:
The new data suggest that incineration of the PFAS-containing foam at the Cohoes incinerator is not breaking down the persistent chemicals but is “redistributing them into nearby poor and working-class neighborhoods,” Bond says.
“It’s the very definition of foolhardy to try to keep burning these things,” Bond says of PFAS. “By design, they resist thermal degradation.” [Bold mine.]
I will end this post with an article by Ross Paznokas of Firetrace regarding the fire risks of industrial wind turbines along with the accountability of owners and operators in relation to proper fire risk assessments and prevention.
A wind turbine fire in Doddington, England. Photo courtesy of the Cambridgeshire Fire and Rescue Service
Despite being the second leading cause of reported incidents in wind turbines, the wind industry is still largely overlooking fire risk.
Few sights are more dramatic than that of a wind turbine on fire. Though rare, the spectacle of rotating flames and falling debris live long in the memory.
Even so, despite the high-profile nature of these events, there is little in the way of accurate records detailing the number of turbine fires and the extent of the financial damage they cause. Indeed, these facts tend to be known only by insurers and project owner operators.
On Dec. 29, 2022, the Galgenberg wind farm, in southwestern Germany, suffered the loss of a 2 MW turbine to fire. Investigations into the cause of this fire have so far failed to yield a definitive answer, but the operator, Windpark Saar, suspects an issue with the braking system.
This incident followed hot on the heels of a fire at the Diamond Trail wind farm in Iowa County in late October 2022. This fire, spreading to the field and surrounding environment, caused several turbines to be taken offline and demonstrated the disruption a turbine fire can cause beyond simply the loss of a single asset.
Given that fire is the most likely cause of a reported incident in turbines after blade failure, key stakeholders should ask themselves if they are comfortable with the potential losses incurred by a fire. If the answer is no, then the follow up question should be: Why am I taking the risk when there are tried and proven solutions out there?
Barring a lightning strike in a storm, preventing fires in wind turbines is actually very straightforward once the turbine is equipped with appropriate fire suppression technology. As such, it is accountability, and not opportunity, that is proving to be the real stumbling block when it comes to mitigating this avoidable risk.
The assumption that someone else is responsible for managing fire risk, rather than it being a collective effort, all too often means that no one is managing fire risk at all. Here’s how each group can take responsibility:
Owner operators. Project owner operators play a pivotal role in changing the approach to fire risk management. The common belief among owner operators is that fire risk has been “designed out” at the manufacturing stage. Though OEMs have made great strides in design and safety, high-voltage electrical equipment can and does occasionally fail. Developers are experiencing such time and financial pressures that installing fire suppression technology is not often prioritized. The duty is, then, passed onto the owner operator to either do nothing, or arrange to retrofit the technology once they have completed commissioning.
Unless developers and owner operators are on the same page, the likelihood is that the appropriate technology is never fitted, the risk is never managed and, implicitly, insurers are relied upon to cover the costs if the asset is destroyed by fire.
In the case of the recent event in Germany, the loss of the asset to fire is presumed to have been caused by a braking system failure. This is unexpected given that the model was only seven years old and presumably well maintained. This should serve as an example to owner operators that, though tempting to dismiss turbine fire as an unlikely event, there is always an element of unpredictability that makes installing fire suppression technology essential to defend against the worst-case scenario of a catastrophic fire.
Ultimately, wind turbines are high-voltage machines that are subjected to harsh weather conditions. Degradation and maintenance needs are to be expected. To this end, high-voltage cabinets, transformer rooms, brakes and slip rings are all routinely checked for signs of wear. However, even though it is easy to equip the technology, not all of these parts are protected from fire risk.
Fire incidents on wind turbines are, thankfully, not common. The probability of wind turbine fire ranges between one in 2,000 to one in 7,000. However, the overriding point should be that it is a possibility threatening turbines every year. Owners should not only keep in mind the cost of a lost asset, and downtime, but also significant increased insurance rates after a fire event, which go on for the life of the project. The current practice of retrofitting fire suppression systems only after a fire event, rather than proactively, is unsustainable.
Between owner operators and developers lies the opportunity to address fire risk before it burns a hole in the owner operator’s pocket.
Insurers. If the hardening of the insurance market is anything to go by, insurers are aware of this responsibility vacuum and are acting accordingly, even as more insurance capital floods into the sector. Owner operators who underwriters deem to be ignoring their fire risk responsibilities are at the mercy of increasing premiums.
The loss of an asset to fire exposes insurers to heavy claims. It is not just the potential millions of dollars needed for cleanup and turbine replacement, but also the business interruption during downtime that can amount to as much as $2,000.00 of lost revenue a day. Since the average downtime after a fire is between 12 and 18 months, insurers are looking at extra hundreds of thousands of dollars in additional claims.
With this in mind, the more owners rely on insurers to wear these risks, the more they are inviting insurers to increase deductibles and remove business interruption coverage to re-balance the underestimation of their risk portfolios. Data from GCube show that insurers have seen a 38% increase in business interruption claims since 2016, which would justify such decisions in future.
However, this approach does little to encourage owner operators to take control of the risk themselves. By raising premiums instead of incentivizing the retrofitting, or requesting, of fire suppression systems, there is a concern that this supports the industry attitude that the bill for fire damage belongs to the insurer.
A simple step to actively reduce the volume of annual claims related to fire is to take advantage of the bankable fire detection and suppression solutions that are available to the renewables industry. Plenty can be learned from more mature industries where insureds can expect discounted terms when they adopt proven fire risk-protection technologies.
Policymakers and regulators. While regulation of the wind sector has been fairly lenient in Europe, it is even more so in the U.S. At present, the National Fire Protection 850 code is the sole legislation that wind projects have to comply with – but this legislation applies generically to all forms of power generation and offers recommendations rather than requirements.
Consequently, there is still no obligation that owner operators carry out a fire risk assessment on their wind projects. This, at a time when wind power is set for historic expansion across the U.S. and to become one of the main sources of utility-scale energy, is unacceptably relaxed.
Given the anticipated growth of the industry over the next few years, it is possible that regulators will also introduce uniform guidelines on fire risk. Why wait to be told to manage this risk when you can manage it today?
Ross Paznokas is global business development manager, clean energy, at Firetrace, a company that develops systems designed to detect and suppress fires in multiple applications.
