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Late on June 17, 2012, calls were made to the Cabazon, Calif.-based fire department reporting a wind turbine on fire. The turbine was dropping hot debris to the ground, and because there were sustained 20-25 mph winds, the resulting wildfire quickly grew to 200 acres by midnight. Consequently, some nearby residents evacuated.

By the next evening, the fire was declared contained after burning through 367 acres of land. It appears in this case that a fire started in the nacelle and then dropped hot or flaming debris, which subsequently ignited the vegetation on the ground. Wildfires, unlike other natural disasters, can both damage a wind turbine and be caused by a wind turbine itself. In fact, the possibility of a wind turbine igniting a wildfire is gaining the attention of fire investigators across the U.S.

For example, the Texas A&M Forest Service added “wind turbine” as a possible sub-cause to a wildfire in its incident reporting in February 2012. Furthermore, the most recent edition of the “Wildfire Origin & Cause Determination Handbook,” published in August 2012 by the National Wildfire Coordinating Group, has a new section on wind turbines.

If a wind turbine starts a wildfire, the financial losses include not only the turbine, but also the costs for the firefighters and other losses from the fire, should it spread beyond the owner’s property line. This consideration makes wildfires an especially important concern for manufacturers, as well as owners and operators of wind farms, as they may be held liable for damages resulting from a wildfire started by one of their wind turbines.

Despite the potential for a wildfire to involve wind turbines, perhaps a more urgent question to a wind farm owner is: How likely is it that such an incident will occur?

There are no compiled statistics detailing wildfires and wind turbines. Therefore, to evaluate the risk of a wildfire involving wind turbines, the U.S. Forest Service’s Fire Modeling Institute map signifying potential for wildland fires provides a more useful analysis.

This map, which was created in 2012, gives the relative potential for a wildfire based on the fire’s ability to spread. Figure 1 shows a map of the wildfire potential with the relative values of potential color-coded between “very low” and “very high.” Each dot represents a single wind turbine. This can be misleading because California and Texas lead the country in number of installed turbines, whereas the map appears to show more installations in the midwestern states. This is simply because more wind turbines are in large wind farms in California and Texas, whereas the midwestern states have either smaller farms or more single-turbine installations. The map shows that there is an increased risk for wildfires throughout the western and southern U.S., whereas the Midwest and Northeast have either a very low or almost no risk (non-burnable land) of wildfires.

The states in Figure 2 all have 25% or more of their turbines in an area with moderate or higher potential for wildfire. Furthermore, California, Washington and Idaho have an especially high fire risk, with significant percentages of their turbines located in regions with high or very high wildfire potential. For example, 38% of wind turbines installed in California are in such regions.

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Means of protection

In order to protect wind turbines from becoming involved in wildfires, there are some methods that are effective. For example, an active fire suppression system installed in the nacelle and/or electrical cabinets is an important asset. A particular benefit of using a fire suppression system is that if it is able to eliminate the fire at an early stage, the rest of the turbine could be left unharmed. This could limit losses to simply the replacement of the failed part rather than an entire turbine.

Another means of protecting wind turbines from wildfires is to install and maintain a firebreak around the turbine. This is an area of land where vegetation and organic matter (i.e., fuel for the fire) is removed in order to prohibit or significantly reduce the spread of a wildfire. A firebreak is an important tool to have before a fire occurs: It would help limit the spread of a wind-turbine-generated fire and could even help protect a wind turbine exposed to a wildfire. The area and dimensions of the firebreak would have to be designed specific to that wind farm, as the firebreak’s size would depend on the type of falling debris expected during a fire and also the makeup of the vegetation on the ground.

In western and southwestern states such as California, New Mexico, Washington, Idaho and Texas, operators should make sure that they are giving extra consideration to the risk of wildfires. For operators in these states, it is important to evaluate sites specifically with an eye on wildfire ignition, spread and containment. Although this article has looked only at the U.S., the concern of wildfires and wind turbines is truly an international concern. It is up to the manufacturers, owners and operators to ensure that wind turbines operate safely. w

 

Robert W. Whittlesey, Ph.D., is an associate at Los Angeles-based Exponent. He can be reached at (310) 754-2761 or rwhittlesey@exponent.com.

Industry At Large: Environmental Impacts

Wind Turbines And Wildfires: Is Your Wind Farm In Danger?

By Robert W. Whittlesey

Although wildfires caused by malfunctioning wind turbines are extremely rare, owners and operators can take precautions to prevent such incidents from spreading.

 

 

 

 

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