Fire is the second leading cause of accidents in wind turbines after blade failure. When a fire does occur, the typical action is to wait for it to burn out. Without suppressing the fire, significant damage is caused which results in considerable repair costs and lost revenue due to downtime.
To illustrate, a single 2.5-3MW commercial-scale wind turbine costs between $3-4m, with the value of the output averaging $2,800 per day. Even a minor fire can have devastating financial impacts with weeks of downtime. The average total cost of a wind turbine fire is $4.5m.
There are generally three main causes of wind turbine fires: mechanical failure, electrical malfunction, and lightning strikes.
A small fire can accelerate quickly in a nacelle that comprises highly flammable resin fiberglass. Internal insulation in the nacelle, which can become contaminated by oil deposits, further adds to the fuel load. Lightning strikes also pose a uniquely high- risk due to both the turbines’ exposed locations and their height; turbines are now being built in excess of 450ft.
Despite the high fire risk in wind turbines, there are relatively few widely reported incidents in the industry. But from discussions with wind farm owners, turbine manufacturers and insurers, it’s certain the losses from fire are much more frequent than publicly documented.
A 2014 report published for the International Association of Fire Safety Science set out to quantify the true number of wind turbine fires and their impact. In the UK, where the report was published, the findings attracted attention-grabbing headlines in major newspapers such as wind turbine fires ten times more common than thought, and wind turbine fires are hidden peril.
Since 2011 there have been 36 large wind turbine fire incidents reported in the mainstream media. One of the worst recorded incidents in recent times took place in California in 2012. More than 100 firefighters were required to put out a wildland fire that spread across 367 acres, which could have been far worse if not for a witness. The final report indicated equipment failure, specifically an arch flash, was to blame for the fire.
In Wyoming, a wind turbine caught fire and caused a wildfire that burned out nearly 1,600 acres. Dramatic cases such as these always hit the front page.
In the social media era news travels fast. Traditional media attention is amplified by witnesses sharing news online, often videos of burning wind turbines taken on camera phones. All this has resulted in increased public awareness of wind turbine fires.