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Why the wind industry cannot afford the financial and reputational damage that even a single turbine fire can bring. By Angela Krcmar.

The wind industry has underestimated fire risk for decades. Even now, statistics around fire losses are based on estimates and incomplete datasets.

This article was originally published in Power Engineering International Issue 5-2020. Read the mobile-friendly digimag or subscribe to receive a print copy.

For a time, the industry could get away with not fully managing fire risk, as the size and number of assets per owner were low enough for many to not experience a fire in their portfolio.

However, as turbines begin to scale up and wind takes on a greater share of national energy mixes across Europe and North America, the industry cannot afford the financial and reputational damage that even a single turbine fire can bring.

Wind turbines catch fire primarily due to electrical or mechanical faults leading to ignition which spreads to the surrounding plastics and fibreglass nacelle.

Turbine fires tend to originate in the nacelle at one of three points of ignition – converter and capacitor cabinets, transformer or the brake.

Converter and capacitor cabinets are necessary for the wind turbine to translate the variable frequency and amplitude of generated energy into a constant frequency and voltage that can be fed into the grid.

However, an electrical fault at these components can produce arc flashes or sparks, which can surround plastics in the cabinet and result in a fire. Transformers, which similarly convert energy into an appropriate voltage for the grid, can also be a point of ignition due to electrical faults.

Nacelle brakes are utilised in an emergency along with blades pitching to stop the turbine blades from spinning in seconds. This generates an enormous amount of friction and heat, and a mechanical fault at the nacelle brake can easily result in a fire.

Financial risk of fire

The rate of fires has remained consistent over the past decade according to available data – typically one in every 2000 turbines will burn down every year. While technologies which are less susceptible to fire such as electric braking systems have been developed, many of the key ignition points are necessary for electricity generation and as such, cannot be designed out of the turbine.

While the frequency of fires has remained constant over the years, the financial risk of fire has increased with the size and complexity of turbines. As turbines are getting increasingly bigger and therefore more expensive, a single fire can have a much greater impact.

“Turbine fires tend to originate in the nacelle at one of three points of ignition – converter and capacitor cabinets, transformer or the brake”.

Additionally, as wind farms scale up from dozens of turbines to large, 100+-turbine projects, owners must account for the greater probability that their largescale projects will experience a fire over the course of the project’s 25-year lifetime.

Most wind turbine fires completely destroy the turbine. Given projects tend to be sited far away from the community, by the time the local fire authority reaches the sight, the fire will have reached a size that spreads from inside the nacelle to throughout the turbine.

Once a fire reaches this size, there is no way to put it out. As the average turbine hub height is over 80m, a fire at the nacelle is out of range for ground-based firefighting, while sending a team up to put the fire out would constitute a significant health and safety risk.

However, if fires can be suppressed while still localised to the nacelle, the turbine will face minimal damage. While fire-resistant materials can slow the spread of a fire throughout the turbine and reduce the chances of ignition, only fire suppression systems can put out a flame once it has been set.

An automatic fire suppression system detects a fire and snuffs it out, either at the point of detection (direct) or by flooding the nacelle with a suppressant agent (indirect).

Installing a fire suppression system at the three most common ignition points in the nacelle will ensure that any fire damage to the turbine is minimal and allow it to continue operating without replacement.

Given the average fire suppression system costs between $4,500 and $13,000 depending on size and whether it is direct or indirect, and based on the expected frequency and cost of a wind turbine fire as outlined above, the benefit of full protection for a 3MW+ turbine significantly outweighs the cost of installation.

Protection measures

Fire risk is not only a concern for the wind farm owner. A wind turbine fire can spread to the surrounding environment, sparking wildfires and potentially spreading into nearby communities.

As such, stakeholders at the government and community level are increasingly pushing to ensure that wind turbine fires are suppressed before the flames can spread beyond the asset.

A growing list of authorities in Germany, and a number of both local and state governments in the US, are acknowledging that fire suppression is necessary to protect new wind farms and their surroundings in the event of a fire in a wind turbine. Regulators in Ontario, Canada have taken it a step further, enabling local authorities to insist that fire suppression is retrofitted to existing sites.

In addition to compliance with government regulators, wind farm owners and operators must also communicate their commitment to fire prevention and protection with landowners and other community stakeholders.

By taking the right steps to fully protect a turbine from a fire incident, the industry can not only reduce the financial penalties of replacing a wind turbine but also ensure better relations with the communities powered by renewables.

With the goodwill of local stakeholders and evidence for tackling key concerns, the wind industry will be in a better position to continue its unprecedented growth.

ABOUT THE AUTHOR

Angela Krcmar is Global Sales Director at Firetrace. She has
over 10 years of experience in the fire protection industry
focusing on the renewable sectors including wind and battery
storage. She is a member of the AWEA Wind Environmental,
Health, and Safety Standards Committee Meeting and the NFPA
855 Committee for Standard for the Installation of Stationary
Energy Storage Systems.

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