Wind turbines may catch on fire ten times more often than is publicly reported, putting nearby properties at risk and casting doubt on their green credentials, researchers have warned.
The renewable energy industry keeps no record of the number of turbine fires, meaning the true extent of the problem is unknown, a study backed by Imperial College London finds on Thursday.
An average of 11.7 such fires are reported globally each year, by media, campaign groups and other publicly-available sources, but this is likely to represent just the “tip of the iceberg”.
There could in fact be 117 turbine fires each year, it argues, based on analysis showing just 10pc of all wind farm accidents are typically reported.
Fires tend to be “catastrophic”, leading to turbines worth more than £2 million each being written off, because the blazes occur so high up that they are almost impossible to put out, it warns.
Turbines are prone to catching on fire because their design puts highly flammable materials such as hydraulic oil and plastic in close proximity to machinery and electrical wires, which can ignite a fire if they overheat or are faulty.
“Lots of oxygen, in the form of high winds, can quickly fan a fire inside a turbine,” it says. “Once ignited, the chances of fighting the blaze are slim due to the height of the wind turbine and the remote locations they are often in.”
It warns: “Under high wind conditions, burning debris from the turbine may fall on nearby vegetation and start forest fires or cause serious damage to property.”
The main causes of fires are lightning strikes, electrical malfunction, mechanical failure, and errors with maintenance, it finds.
The academics used data compiled by the Caithness Windfarm Information Forum (CWIF), an anti-wind lobby group, which records 1,328 accidents involving wind farms globally between 1995 and 2012. Of these, 200 – 15 per cent – involved turbines catching on fire, implying 11.7 fires per year.
But the report, published in the journal Fire Safety Science, also back CWIF’s view that the true number is far higher.
It points out that the wind industry body, Renewable UK, has admitted there were 1,500 wind farm accidents and incidents in the UK alone between 2006 and 2010 – while just 142 individual accidents in the UK were documented in CWIF’s database over the same period.
This implies that less than 10pc of incidents are publicly reported.
Dr Guillermo Rein, of the Department of Mechanical Engineering at Imperial, said: “Fires are a problem for the industry, impacting on energy production, economic output and emitting toxic fumes. This could cast a shadow over the industry’s green credentials. Worryingly our report shows that fire may be a bigger problem than what is currently reported.”
He told the Telegraph he believed it was “the responsibility of the industry” to keep a proper database and believed the industry itself had been “surprised by the magnitude of the problem”.
UK cases highlighted in the report include a 100-metre tall turbine that caught fire during hurricane-force winds at Ardrossan in North Ayrshire in December 2011, reportedly due to a lightning strike. The wind turbine was completely burnt out and debris scattered over large distances due to the strong wind.
In 2005, a turbine at the Nissan factory in Sunderland was engulfed in fire before falling onto a nearby A-road, causing traffic disruption. The blaze was believed to be caused by a loose bolt jamming a mechanism, causing it to overheat.
Dr John Constable, director of Renewable Energy Foundation, which has published research showing that wind turbine performance declines sharply with age, said: “This new study on wind turbine fire hazards is an important reminder that there are hidden operation and maintenance costs affecting the economic lifetime of what is after all very expensive equipment. Just because the wind is free doesn’t mean that it is a cheap way of generating electricity.”
A spokesman for Renewable UK said it did “not have numbers of fires as in many cases these do not need to be formally reported”.
Renewable UK’s director of health and safety, Chris Streatfeild, said: “The wind industry welcomes any research that will help reduce maintenance times and improve safety standards. However, the industry would probably challenge a number of the assumptions that are presented in the research, which include the questionable reliability of the data sources referenced and perhaps more importantly a failure to understand the safety and integrity standards for fire safety that are in effect standard practice in any large wind turbine.”
He said: “Fire is a very important issue for the industry in terms worker and public safety as well in reducing costs through minimising any operational down time. However the operational practices and design standards are such that the actual safety risks associated fire are extremely low. No member of the public has ever been injured by a wind turbine in the UK.”