As the global need for energy increases, and concerns on the impact that we are having on the environment, the demand for renewable energy grows. Wind power has a low environmental impact, and when comparing to conventional energy sources reduces carbon emissions, saves billions of gallons of water, and decreases the output of pollution. Over the previous five years, the increase in output from wind turbines has nearly doubled and can cover more than six percent of the global electricity demand. As more and more wind turbines come online and the fleet of current wind turbines age, there is a likely increase in wind turbine accidents, including wind turbine fires.
Due to the remote location of many wind farms and no current required reporting of turbine fires, a significant number of wind turbine fires go with it being known. However, in this day in age, with quick access to the camera on your phone and the ability to post to social media from nearly anywhere, more wind turbine fires are being exposed. When comparing to other energy industries like oil and gas that have thousands of fire accidents a year, fire incidents in wind turbines remain relatively low. Still, the impacts are significant from replacement costs to downtime to environmental impacts.
In 2019, according to the World Wind Energy Association (WWEA), the growth rate of the wind market was 10.1 percent, the second strongest year in terms of market size. At the end of 2019, the global capacity of wind turbines was 650.8 Gigawatts. What does this mean in terms of fire risk for wind turbines? With the capacity of wind turbines increasing, the risk of fire also increases. Fires in wind turbines are the second leading cause of accidents after blade failure and are ahead of structural failure.
Research conducted by Caithness Windfarm Information Forum (CWIF) found that over the last five years, the average number of wind turbines fires was 25.4. Other researchers feel the number of cases of turbine fires is significantly underestimated based on the fact that there is no required reporting for turbine fires. Also, in the case of official reports, the reports can be incomplete, biased, or contain non-publicly available data. In a previous report, the Telegraph and Renewables UK both have estimated that 91 percent of wind turbine fires go unreported. With the average cost of a wind turbine fire at $4.5M, the annual financial impact could be anywhere from $114.3M to $1.35B.
Wind turbine fires are most likely to occur in the nacelle. Components within the nacelle are combustible and vulnerable to fire. Highly flammable materials like the hydraulic and transformer oil and plastics are located near electrical wiring and equipment. If an ignition source is introduced, a fire can start quickly and spread. Another area of concern in a turbine is the base of the tower. This area contains electrical monitoring equipment, which under the right circumstances, a failure can happen, leading to a fire.
For a fire to start, you need an ignition source. The number one cause of wind turbines fires is lightning strikes. Other causes are electrical or mechanical malfunctions and human error. These include:
When dealing with fire risk factors, both the age of the turbine and geographic location can play a role. As fleets of wind turbines are getting closer to reaching the end of their lifespan, they pose a higher risk due to the aging components, wiring, etc. The geographic location can also have an impact. In areas with warmer and drier climates, cables, transformers, nacelle components, and the control cabinet are more susceptible to deterioration due to the temperature. All wind turbines should be on a strict routine maintenance schedule to ensure all components are in good working condition.
Based on research conducted by CWIF, since 2000 there have been 385 documented wind turbine fires. A number of these fires where not only a total loss of the turbine but had devastating consequences. In June 2012, the View Fire, which burned 367 acres in Riverside County, California, was caused by a wind turbine fire. Nearby residences were evacuated, and over 100 firefighters fought the wildfire to get it contained. A little over a year later, a tragedy that the wind industry had not yet experienced occurred. In October 2013, two young mechanics became trapped on top of a burning wind turbine and died as a result at the Piet de Wit Wind Farm. Because of the height of turbines, a specialized team of firefighters was called to battle the fire and recover the victims.
More recently, in the US, two wildfires were sparked from wind turbine fires. In July 2019, melted debris falling from a turbine fire caught the surrounding grass and brush on fire to cause the Juniper Fire wildfire, which put 39 structures in danger. It took almost 200 fire crew members to contain the 250-acre fire over three days. A turbine fire on August 26, 2019, is blamed for the Rhodes Ranch 3 Fire outside of Abilene, Texas. Record-setting temperatures and rough terrain increased the challenges for firefighters. Fire crews on the ground watched over the containment lines while aircrews spread fire retardant and water on hot spots. Luckily, in both cases, there were no reports of injury or structural damage.
When it comes to battling wind turbine fires, it is nearly impossible to do so using traditional fire fighting techniques. The location of wind farms, accessibility to individual turbines, and availability of water can be a challenge. Not to mention the height of turbines and the potential of the blade still rotating while on fire. The likely outcome for wind turbine fires is letting the turbine burn until it extinguishes itself.
Just as there is no official required reporting of wind turbine fires, there is not an international or national mandate for fire protection requirements. The most recognized guideline, but not a requirement, is the NFPA 850, which recommends fire protection for electric generating plants and high voltage direct current converter stations. Also, in the U.S., the Occupational Safety and Health Administration (OSHA) strongly recommends the installation of fire protection equipment. Wind farm operators having rigorous safety standards and programs in place, do adhere to these guidelines, and implement fire protection measures.
The common types of fire protection equipment for wind turbines include smoke, heat, and flame detectors, as well as fire suppression systems. When a fire is identified, a detection system can send information to a central alarm system that initiates the shutdown of the turbine’s components. It can also activate a fire suppression system.
By adding automatic fire suppression systems within the wind turbine, you are able to protect components and areas that are prone to fire. This extra layer of security reduces the risk of having a catastrophic event. Once a fire is detected, the fire suppression system activates to suppress the fire before it can spread uncontrollably.
There are several types of fire suppression systems, of which some are better suited to protect wind turbines. Any type of water-based system, including sprinklers, water mist, and foam water are not ideal for protecting wind turbines due to the limited space, accessibility to water, and the damage caused to critical components. For onshore turbines, carbon dioxide (CO2) systems need an airtight environment to successfully suppress a fire. A benefit of CO2 is that when discharging, no residue remains, and it will not harm electrical components. The disadvantage is that CO2 has significant risks to humans if they are present during the discharge.
Aerosol-based fire suppression systems provide total flooding capabilities, gaseous matter, and ultra-fine solid particles. These systems require minimal maintenance and are considered environmentally friendly. The downside is that the system is also not safe for occupied spaces and can leave a residue causing damage to critical components.
The last option for wind turbine fire suppression systems is clean agent systems. These systems utilize suppression agents, like Chemours FM-200 and 3M Novec 1230, which are environmentally safe, leave no residue, does not damage equipment, and is safe for people in occupied spaces. The systems require minimal space for the clean agent cylinders and are less likely of a false discharge. Systems like Firetrace, do not require electricity and use fire detection tubing that is routed around fire-prone areas within the wind turbine. Once a fire is detected, the tubing will burst, activating the systems to release the clean agent to suppress the fire.
Without regulations or mandates, it is the discretion of wind farm owners to protect wind turbines from fire risks and damage. As replacement costs escalate, loss of revenue from downtime, and reputational damage, protecting wind turbines from fire is crucial. Fire suppression systems offer the protection wind farm owners need. As noted, there a variety of different types of fire suppression systems. It is key to select a system that is the most compatible with the equipment and areas you are protecting.