Today’s spectacular wind turbine fire at Cargill’s Hull factory is likely to have been triggered by either an electrical or mechanical fault.
The huge turbine was installed in early 2008 by the site’s then owners Croda International after securing planning approval the year before. At the time it was Hull’s first large wind turbine.
Until then, similar onshore wind farm developments in the East Riding had featured clusters of between seven and nine turbines in open countryside designed to feed power to the National Grid. In contrast, the Croda scheme broke new ground by using a single turbine to generate power for a specific industrial site in an urban setting.
Standing 125 metres tall, it became an instant landmark on the city’s horizon with a maximum capacity of generating two million watts of power. That’s enough to run 1,000 electric toasters simultaneously.
Although the cost of the development was not revealed at the time, similar-sized single turbine installations usually cost around £2.8m at today’s prices. The typical operational lifespan of a modern wind turbine is 25 years so, by that measure, the Hull turbine was already middle-aged before today’s fire started.
It’s clear from the images of the blaze that it was largely confined to the nacelle which is the casing sitting on top of the turbine tower. This houses gears which convert the relatively slow rotation of the spinning blades into higher-speed motion and the generator which acts like a giant version of a dynamo on a bicycle by generating electricity through the movement of the rotor blades.
Industry experts say turbine fires typically happen because of an electrical or mechanical fault leading to ignition which spreads to the surrounding plastics and the nacelle itself which is made from fibreglass. Experts examining the aftermath of today’s blaze will try to pinpoint the specific area where it started.
Transformers in the turbine converting energy into voltage are one potential point of ignition if an electrical fault is confirmed. Similarly, a mechanical fault in the nacelle’s emergency braking system could have also been responsible as the deployment of brakes to stop the blades rotating generates both friction and heat.
Angela Krcmer, global sales director at wind turbine fire safety firm Firetrace International, recently highlighted the issue in an article for Power Engineering International. She said: “The wind industry has underestimated fire risk for decades.
“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.
“The rate of fires has remained consistent over the past decade according to available data. Typically one in every 2,000 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.”
The fire will almost certainly mean the turbine will have to be dismantled. With each blade weighing just over 8,000kg, that’s likely to be a big job.
As the site’s new owners, Cargill will also be responsible for overseeing an in-depth investigation into the cause of the blaze, The sale of the chemicals complex was only completed in late June and previous owners Croda have offered their support. In a statement, Croda said it had used an external specialist company to maintain the turbine.
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