Wind turbines are impressive structures. At times towering over 300’ tall, their blades measure over 100’ long apiece and the tips of those spinning blades can reach speeds of 180 miles per hour. These machines are an efficient means of producing environmentally-preferable power), and the U.S. has experienced a boom in turbine construction in recent years. In fact, the amount of wind power generated in the United States has increased by over 700% in the past ten years, and as of 2016 it led the world in total wind energy production.
Even more impressive-looking than wind turbines are wind turbine fires, and these events get a lot of attention as a result. A Google search turns up thousands of awe-inspiring photos and videos of these machines on fire, along with news stories about the incidents. That same search will also bring up websites of anti-wind-energy groups who use such incidents to fuel hyperbolic claims that we should be living in fear of these structures. So how bad is the issue of wind turbine fires, really?
It’s hard to say exactly. According to the frequently-cited Caithness Windfarm Information Forum (CWIF) there are around 20 total onshore wind turbine fires per year. However, the British newspaper The Telegraph reported in 2014 that these fires may be 10 times more common than CWIF’s statistics claimed, citing data from an Imperial College (London) report and Renewable UK. Clean energy insurer GCube’s estimate is somewhere in the middle ground, claiming 50 incidents a year in their 2015 report Towering Inferno.
GCube, a Lloyd’s of London coverholder, notes that while this number may seem relatively small, these incidents cause owners and insurers a disproportionately large hardship. According to a 2014 report by the International Association for Fire Safety Science (IAFSS), over 90% of wind turbine fires result in total loss of the turbine or severe structural failure of its major components. With a cost of around $4 million each, the replacement bill alone is staggering. Once cleanup and downtime are factored in, GCube claims the bill balloons to $4.5 million per incident—a figure that’s rising.
“The cost of [wind turbine] fires is actually increasing compared to five years ago, mainly due to the arrival of larger turbines,” GCube’s Jatin Sharma told the renewable energy industry magazine Recharge in 2016.
Some of the replacement costs may be covered by the turbine’s warranty, but there are limitations. Jarret Ryan, Installation Division President at ABCO Fire Protection, has been protecting wind turbines for years, and he encourages his customers to familiarize themselves with the actual cost of replacing their investment.
“The manufacturer’s warranty only covers replacement of parts,” notes Ryan, “it leaves out the costly extras like downtime, clean-up, and all of the collateral damage that can come from a wind turbine fire.”
Those collateral costs include dangers posed to bystanders, nearby buildings and vehicles, workers that may be in turbines, and adjacent wildfire-prone areas. These lost dollars, land, structures, and—occasionally—lives, all add to substantial reputational damage. Anti-wind-energy sentiment in many areas is partly fueled by highly-publicized turbine fires. In Australia, an 8400-acre brush fire recently destroyed livestock, outbuildings, and at least one home. The fire was sparked by a freak accident involving a wind turbine, and this has exacerbated longstanding issues between locals and the windfarm operator. In cases like this, a bit of extra diligence on behalf of energy companies may go a long way in healing relationships with the communities they serve and operate in.
Lastly, the environmental cost of structure fires is staggering, with massive amounts of pollution and greenhouse gasses being generated in a short period of time. According to a 2016 article in the engineering industry journal Structure, building sustainability features “…may be negated due to the additional carbon emitted into the environment through combustion of building contents.” It’s not unreasonable to argue that a wind turbine fire may completely negate any environmental benefit of the turbine’s existence—an existence that pivots primarily on being able to generate relatively “green” energy.
Unfortunately, there’s no shortage of fuel on board wind turbines. According to the IAFSS, the main fire-loading comes from the fiberglass-reinforced plastic the turbine nacelle (the large gear-house at the top of a turbine shaft) is constructed of, as well as foam insulation that may be used in the unit. In addition to this, upwards of 235 gallons of lubricating oil and other flammable liquids can be stored inside the nacelle, and thousands of feet of polymer-coated cable run from the nacelle down the shaft to a transformer below.
This fuel seems to be ignited by four main causes: lightning, electrical malfunction, hot surface ignition, and maintenance. IAFSS lists lightning as the most common ignition source of turbine fires, and this risk is exacerbated significantly when lightning protection systems are not installed or maintained. Electrical malfunction can occur in the electrical components inside the nacelle, which includes a high-voltage transformer on some models. Braking systems and other mechanical components result in most of the hot-surface related fires, and pressurized flammable hydraulic fluid found in the nacelle can magnify this hazard.Once the fuel is ignited, what can be done? Typically, not much. Wind turbine heights far-exceed the reach of fire department aerial trucks, making them impossible to put out from the ground. When a wind turbine lights up, the fire department’s first role is to establish a “safe zone” around the expected perimeter of falling debris. They then stand by to extinguish any fire that may spread from the turbine to nearby buildings, vehicles, or wildlands while the $4 million tower burns itself out.
Despite this inaccessibility, abundance of fuel and ignition sources, and high-profile high-cost losses, there is currently no legal requirement to provide fire detection or suppression measures on wind turbines. As with any structure, in many parts of the United States the local authority having jurisdiction (AHJ) may provide fire protection guidance or requirements within the bounds of local codes. However, they often have limited—if any—involvement in wind turbine projects aside from developing a plan of action for their department to follow if the structure goes up in flames. Typically, fire protection measures are only installed on wind turbines if the owner or insurer requires it.
As the wind energy industry struggles to quantify and gain consensus on the problem, the fire protection industry has already developed solutions to protect wind turbines. Over a decade ago, fire system manufacturer Firetrace began using their small self-contained systems to protect the most fire-prone components of turbines. Then, in 2010 the National Fire Protection Association (NFPA) released a new edition of NFPA 850 Recommended Practice for Fire Protection for Electric Generating Plants and High Voltage Direct Current Converter Stations. This edition began the process of codifying fire protection best practices for wind turbines by adding Chapter 10, “Identification and Protection of Hazards for Wind Turbine Generating Facilities.”Chapter 10 of NFPA 850 includes some helpful tips for wind turbine operators to consider when weighing fire protection options for their units. It includes statements on passive fire protection measures—lightning rods, for instance—as well as the impracticability of some fire suppression options, such as those that require water (sprinklers, mist, or foam systems are examples). Of the recommendations found in Chapter 10 of NFPA 850, those listed under Section 10.5.3.5 “Nacelle Fire Protection,” are the most valuable when considering fire suppression options for turbines. This section outlines what areas of a nacelle should be protected when possible, including: electrical enclosures; gearbox lubricating systems; hydraulic control systems and associated reservoirs, pumps, accumulators, piping, and actuating systems; oil piping and anywhere oil can flow, accumulate, or spray.
“Since there aren’t many rules, which parts of the nacelle are protected is really up to the owner or their insurance company,” says Steve Rice, Installation Operation Manager and former wind turbine technician for ABCO Fire. “We typically always protect the transformer whether it’s in the nacelle or on the ground, as well as the electrical cabinets in the nacelle. Occasionally we protect the braking system, which is really what seems to cause a lot of the fires in turbines.”
Systems that are practical, economical, and listed to protect wind turbine components are few and far between. As mentioned above, Firetrace has the longest tenure when it comes to this type of protection, and was named “preferred and primary supplier of automatic fire suppression systems” by the world’s largest wind turbine manufacturer, Vestas, in 2012. However, other companies have recently developed similar suppression systems that can be used to protect turbines as well. These systems use a thin pressurized detection tube that runs throughout fire prone areas and ruptures when exposed to high heat. The release of pressure from the tube actuates the system, and notifies a monitoring station that the system has discharged. The system itself consists of a relatively small pressurized cylinder filled with a clean fire suppressing agent that will not leave residue or damage sensitive equipment.“A single nacelle typically contains 5-9 small fire suppression systems, each protecting a high hazard area or component,” says Rice, who holds a NICET Level III certification for Fire Alarms and Special Hazards, and is one of three Miller-certified climbers on ABCO’s team. “The idea is for the systems to discharge early and exactly where needed so they take up minimal space in the nacelle, but can still suppress incipient fires before they cause devastating damage,” he continued.
Dividing protection of a single nacelle between several small fire systems has multiple benefits for the turbine operator. For instance, in the event of a fire only the system or systems that actuated need to be recharged, which saves time and money, and keeps the remainder of the turbine protected while the entire unit is brought back online. Additionally, using separate systems to monitor separate hazards can help operators tell exactly where an issue occurred in the turbine.
“The systems we install on wind turbines are typically monitored by a SCADA system,” says Jarret Ryan, referring to the supervisory control and data acquisition systems that are used to monitor and automate turbine operation. “A better term for it these days would be the ‘internet of things,’ but basically when a fire system actuates it sends a signal to the automation system that tells it which system went off, and what action needs to be taken by the turbine. In all of our installations, this has included automatically stopping the turbine from spinning, which in turn stops the generation of electricity and allows personnel to service the unit.”
Automatic shut-down of the turbine upon operation of a fire protection device is a recommendation of NFPA 850, and has become an industry standard. But what happens when a flaming turbine doesn’t stop spinning? A wind energy operator in India found out last summer, and dramatic video of the resulting helix of black smoke violently flinging flaming debris across the landscape went viral shortly afterward.
“These things do catch fire, and when they do there is absolutely nothing you can do about it,” re-caps Ryan. “No fire department that I know of has the ability to put it out, so it’s up to turbine operators to take proactive measures. For a few thousand bucks you can protect a multi-million dollar piece of equipment from fire, and eliminate the collateral costs that are likely to come from a fire event.”
As monuments to clean energy alter our horizon, the fire protection industry’s aim is to help the world maintain a positive outlook when it comes to what may be the most efficient source of “green” electricity. Wind turbine fires are a problem for both the clean energy industry and people who live near wind farms, but viable, economical solutions do exist. From the recommendations of the most recognized fire code body in the world, to proven fire detection and suppression solutions, we’re here and ready when the wind industry needs us.
For more information visit our Wind Turbine Fire Protection page.
Photos courtesy of Steve Rice and Firetrace.
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