Why wind turbine fires happen and what can be done to reduce the risk.
November, 21 2015 | Robin Whitlock | Interesting Engineering
According to an article published by Fire Safety Science, the peer-reviewed publication of the International Association of Fire Safety Science, one of the major challenges faced by the global wind energy industry is the tendency of wind turbines to catch fire, a problem that the article claims is not being fully reported.
The main reason why there is such a large risk of a fire occurring in a wind turbine is because the wind turbine nacelle is a space in which there are highly flammable materials located in close proximity to machinery and electrical wiring. These materials include hydraulic oil and plastics. For example, a 1.5 MW wind turbine can typically contain 900 liters of lubricating and cooling oil, and 1.5 MW machines are now usually on the smaller side of the wind turbine product range due to increasing development and innovation in the last few years, leading to much larger turbine models. Meanwhile, the nacelle itself will almost certainly be made of flammable fibre-reinforced plastic (FRP) and will contain acoustic insulation material which is also flammable.
If the mechanical or electrical components within the turbine nacelle overheat or develop a fault, they can ignite and start a fire. This can then be fanned by the high winds the turbines are designed to exploit. Once a fire starts in a wind turbine it is extremely difficult to put out, due largely to the remote location of the wind farm or individual wind turbine and the height of the turbine itself.
The study claims that, according to the wind energy industry itself, wind turbine fires represent 10 to 30 percent of reported wind turbine accidents, although an accurate picture of the situation is hard to obtain because official reports concerning fires are often incomplete, biased or contain information that is not publicly available. When wind turbine fires occur, they almost always result in considerable downtime or the total loss of the turbine, but the good news, according to the study, is that the ratio of fires per turbine has decreased substantially since 2002.
The research team suggests that the industry could mitigate the risk by installing fire protection measures, such as lightning protection systems, non-combustible hydraulic and lubricant oils and heat barriers to protect combustible materials. Wind turbine manufacturers could also avoid the use of combustible materials and introduce comprehensive monitoring systems in order to provide a constant check on the condition of their turbines. Smoke alarms could also be fitted inside the turbine nacelle in addition to fire suppression systems using water or foam to douse the fire.
Uadiale S., Urbán E., Carvel, R., Lange, D. and Rein, G., 2014. Overview of Problems and Solutions in Fire Protection Engineering of Wind Turbines. Fire Safety Science 11: 983-995. 10.3801/IAFSS.FSS.11-983