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Fire Risk in Wind Turbines

Created on Monday, January 22, 2018 and posted in Fire Safety Articles
Fire Risk in Wind Turbines
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Wind power is an exciting emerging sector that needs those of us involved in fire safety to get onboard. Why? Because in Europe wind power is already the 2nd largest power generation method. A fun fact to give a bit of context is that 1 rotation of an Orsted 8MW turbine blade (takes 6 seconds) can power a regular home for 29 hours. This article takes a look at fire risk in wind turbines and how we can work as an industry to solve it.

As electricity generation becomes more reliant on renewable energy, wind power is becoming increasing important in the energy mix. As our reliance grows on wind turbines, keeping them fully operational and at reduced levels of risk becoming more important, and as a result, so does safety management. There are over 340,000 wind turbines around the world. Yet there are thousands of turbines without any fire system installed.

With predictions of much taller and more powerful turbines of 13-15MW to be implemented by the middle of the next decade, and thus fewer per project, ensuring that the they are in working order is essential, because the larger and fewer the turbines, the more costly they will be to operators in the event of fire damage.

Wind turbines require an active fire protection system, which includes but is not limited to detection (of flames, heat, gas, and smoke), alerting personnel and rescue services, and activating systems for fire suppression or extinguishing.

Coltraco Ultrasonics provide smart Firetest® solutions which enable wind turbine owners and operators to improve their fire safety management and reduce the risks to human life, business continuity caused by any downtime and thus minimise risk to reputation by delivering a Safesite®.

Fires Cause Turbine failure

Turbine fires are expensive. They attract negative publicity. It is estimated that 0.3-0.5 fire incidents occur per 1000 power stations (onshore and offshore) every year. What it more, wind turbine fires tend to cause losses equal to or above the original cost of the wind power plant – especially offshore!

What are the Risks?

Introducing fixed fire extinguishing systems as fire protection is becoming more prevalent because of the increased rate of fire incidents and the rising value and sizes of turbines. While there have been occasional articles written over the last couple of years about the importance of wind energy and the problems of fire, they have not addressed how fire systems themselves can be constantly monitored to ensure operational efficacy and to reduce risk, saving costs and increasing revenues.

Potential ignition sources are mainly inside the nacelle where there is fast moving machinery (generators, gearboxes e.t.c) which creates heat and combustible oil and solid material in the. Even with the incredible engineering and safety measures in place, a fire can ignite and develop, leading to the possible complete destruction of the turbine. A study conducted by SP Safety at the Technical Research Institute of Sweden showed that 10-30% of all loss-of-power-generation incidents in wind power plants are due to fire.

Critical Turbine Incidents

The fires in wind turbines not only lead to a loss of business continuity and a negative impact on the company’s reputation but also, most importantly, are a critical safety issue. Possibly harmful debris can be drifted by the wind in the event if a fire and there is also a significant risk to human lives. When turbines are under erection, commissioning maintenance and repair, escape routes for operators are often long and vertical. Three out of six incidents involve a human presence in the nacelle; hence, a fire becomes a safety concern. In 2013, a crew of four engineers died in Ooltgensplaat, Netherlands in a wind turbine fire. This devastating loss of life calls for improved review of fire safety to minimise the risk to engineers.

Daniel Kopte, expert for safety systems, renewables certification at DNV GL, estimates that worldwide 120 wind turbines suffer fire damage (not necessarily causing total loss) annually. There have been several high-profile cases on wind turbine fires in the UK within the previous 6 years. An 100-metre tall turbine caught fire during hurricane-force winds at Ardrossan in North Ayrshire in December 2011, reportedly due to a lightning strike. The wind turbine was completely burnt out and debris scattered over large distances due to the strong wind. With predictions of much taller and more powerful turbines of 13-15MW to be implemented by the middle of the next decade, and thus fewer per project, ensuring that the they are in working order is essential, because the larger and fewer the turbines, the more costly they will be to operators in the event of fire damage.

Regulations

With some turbines at almost 200m in height, they are effectively outside the range of the fire emergency services; and when it comes to turbines at sea, human intervention in the event of fire is virtually impossible. It is for this reason that the NFPA 850 Recommended Practices suggest guidelines and AHJs and other fire inspectorates, consultants, associations, the insurance companies and the OEMs themselves all have a role in play in developing good codes of conduct.

Wind turbines require an active fire protection system, which includes but is not limited to detection (of flames, heat, gas, and smoke), alerting personnel and rescue services, and activating systems for fire suppression or extinguishing. Due to the height and location of wind turbines, classic firefighting methods come up against their limits and therefore fire extinguishing systems that use gases such as carbon dioxide, inert gases or clean agents such as FM-200® and Novec™1230, which are especially appropriate for dealing with fires in electrical systems because they extinguish the fire quickly.

However, it is important to note that such fire extinguishing systems require maintenance to ensure they are fully operational and ready in event of a fire. ISO 14520-1:2015(E) assumes that these systems accidentally discharge and leak. 6.2.4.2 Contents indication: “Means shall be provided to indicate that each container is correctly charged.” Followed by “9.2.1.3 The storage container contents shall be checked at least every six months as follows. a) Liquefied gases: for halocarbon agents, if a container shows a loss of agent in quantity of more than 5 % or a loss of pressure (adjusted for temperature) of more than 10 %, it shall be refilled or replaced.”

Section 10.5.3.2.2. of the NFPA 850 states that the Maintenance and inspection of total flooding gaseous agent systems and interlocked equipment are critical. All systems at some time maybe called upon to operate in an emergency situation and may help in saving life and property. It is for this reason that knowledge must be had that the system can operate to its full potential.

How to Inspect Fire Suppression Systems

There is a clear trend toward including fire suppression in newer units, but with systems, comes the requirement of maintenance. The assumptions in the installation, commissioning and maintenance of gaseous extinguishing systems are that they are highly pressurised and thus risk leaking and discharging, hence why annual inspections are required.

Large wind companies, such as E.ON, have now begun investing in both in-house and third party operations and maintenance, driven by safety and quality concerns. Inspection should include an evaluation that the extinguishing system continues to provide adequate protection for the risk. This is essential under ISO 14520 where gaseous extinguishing systems have to be designed in relation to the discharging agent hold-time (if the room cannot hold the agent because of leaks the agent will disperse and not extinguish the fire) and discharging agent peak pressure (if the pressure is too high for partition walls or suspended ceilings they will be blown apart or damaged and possibly destroying the room integrity). However, routine maintenance is liable to be overlooked or given insufficient attention by the owner of the system.

Are Annual Check Sufficient in Risky Environments?

Given that offshore wind parks require huge investments and are difficult to reach in the event of a fire, an emergency automatic fire extinguishing systems is a must for insurance cover. But what if the suppression systems that are installed in the turbines to protect life and infrastructure do not release on actuation? Gaseous extinguishing/suppression systems are installed to protect against special hazards in critical infrastructure as their key objective. They deliver the infrastructural resilience that wind turbines require. If it is a known fact that there is a long response time to wind turbine fires, then it is unacceptable that the dynamic suppression systems are left unattended 364 days a year.

A Call for Constant Monitoring of Wind Turbines

There is a call for remote fire alarms in the turbines due to the lack of easy fire servicing stations, so why not also for the gaseous systems? Why have an alarm system to alert fire services of the fire if the protection system cannot secure the nacelle? A dynamic system needs monitoring. The reality is that gaseous systems are checked for contents annually because they are pressurised and anything that is dynamic offers risk of loss of contents, but this fails to deal with the probability of discharge or leakage for the 364 days per annum in the interim between certification checks.

Gaseous extinguishing/suppression systems are installed to protect special hazards in critical infrastructure as their key objective. If the hazard is special and the infrastructure critical then this is the case for the constant monitoring of the suppression systems that aim to deliver the protection of them.

Coupled to this is a complete lack Room Integrity testing after the gaseous system has been installed. As buildings age or their internal use is changed leak sites develop. If the gas cannot be “held” in the room on discharge during a fire event the probability of its suppression diminishes in direct proportion to the size of the leak sites. Room integrity tests are imperative for the determination of both the Hold-Time and the Peak Pressure needed for successful fire suppression.

The level of leakage is carefully monitored in order to ensure the correct agent concentration is achieved; room integrity must be ‘tight’ enough to ensure sufficient retention time according to NFPA or ISO, yet remain ‘loose’ enough to prevent enclosure damage at discharge. The presence of undesired and unregulated leak sites reduces room integrity and will hence dramatically impact the Hold Time and Peak Pressure, placing room contents and potentially wall structures at risk. It is accepted that in wind turbines vibration can loosen connections while dirt, dust, and temperature extremes are known to cause unwarranted discharge. Additionally, openings in the turbine housing significantly inhibit achieving the designated agent concentration. Devising a solution to overcome these challenges can add significantly to the weight in the turbine.

Fire Test Solutions to Deliver The Safesite

Focused on continued advancement of safety technology, Coltraco have now developed the Permalevel® Multiplex, a fixed fire suppression monitoring system, designed for continuous contents verification. Permalevel® is designed to ensure that fire suppression systems are always fully operational and that no accidental discharge has occurred, which could affect the effectiveness of the overall fire protection system in the event of a fire. With guaranteed systems operations, adaptability for purpose, 24/7 remote access to the systems status, an interruptible power supply and remote real-time monitoring, the Permalevel® offers the efficiency that is needed in a wind turbine.

For regular inspection, the Portalevel® MAX is a handheld ultrasonic liquid level indicator, which can service a cylinder in 30 seconds (in contrast to 15minutes by traditional manual weighing) with accuracy of up to 1.5mm off the true liquid level. Portalevel® MAX builds on Coltraco Ultrasonics’ 30 years’ experience in designing, manufacturing and supporting ultrasonic liquid level indicating equipment, in 108 Countries and numerous market sectors and environments. The development program was born out of the desire to further improve on Coltraco’s existing 8 designs and taking on board feedback and opinions of our customers.

Coltraco Ultrasonics provide smart Firetest® solutions which enable wind turbine owners and operators to improve their fire safety management and reduce the risks to human life, business continuity caused by any downtime and thus minimise risk to reputation by delivering a Safesite®.

For more information visit on Fire Risk in Wind Turbines visit www.coltraco.com/


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