Fires are a major cause of wind farm failure, according to new research

*** UPDATE TO NEWS RELEASE: 'Fires are a major cause of wind farm failure, according to new research' ***

Message to news release subscribers from Imperial College London Press Office:

Following discussion with reporters we wish to draw attention to further information relating to the News Release issued under embargo for Thursday 17 July 2014: "Fires are a major cause of wind farm failure, according to new research". A version of this note will be appended to the online news release and news story and both will be updated accordingly.

1. The purpose of the research study:

In the abstract of the paper, 'Overview of Problems and Solutions in Fire Protection Engineering of Wind Turbines,' the authors state that the wind energy industry is one of today's leading industries in the renewable energy sector, providing an affordable and sustainable energy solution. The poor statistical records of wind turbine fires are a main cause of concern and hinder any research effort in this field. The paper aims to summarise the current state of knowledge in this area by presenting a review of the few data sources which are available, in order to quantify and understand the fire problem in wind energy. The authors hope that a proper understanding of the problem and its scale will allow for development of the best fire protection engineering solution, as the need for such a solution is vital to the sustainability of wind turbines and to the growth of the wind energy industry.

In summary, the authors have taken available data and pointed out that there is a problem with fire (not that this is the biggest problem that affects wind turbines, which is blade failure). They then set out possible solutions to this problem.

2. The authors of the study published it in Fire Safety Science, the peer-reviewed publication of the International Association of Fire Safety Science, and they stand by their published paper. The research underwent an independent peer review process arranged by the editors. Three reviewers read the work and asked for minor revisions. In their report the authors clearly state that they reached their conclusion based on all the data that is publicly available. The paper can be accessed at: http://www.iafss.org/publications/fss/11/200/view

3. Since the publication of the paper, the lead Imperial author has made remarks on his blog about the estimate of the number of wind turbine fires. The relevant excerpt from the blog is as follows:

18/7/2014 Update: Our 10-times extrapolation that we apply in the paper is based on the assumption of uniform failure rates for all failure types (blades, fire, structure, etc). This assumption is not a strong one and would need to be double check with higher quality data. Among all the conclusions of our paper, I feel that the 10-times higher number of fire accidents is not the most important or stronger one. We could have emphasized this weakness.

The full blog entry is at: http://guillermo-rein.blogspot.com 4. The lead Imperial author and the Imperial Press Office have updated the News Release based on the peer-reviewed study, as follows:

a. Regarding the line, "The team found that ten times more fires are happening than are being reported.": The Imperial author and the press office accept that readers relying only on this line and without reference to the following line, which states that the researchers were estimating the increased number of fires annually, or the detail in the paper, could assume that the researchers had strong evidence to inform this statement, rather than understanding it as an estimate based on the available data, which, as the paper itself highlights, is incomplete.

Therefore the updated version of this section of the News Release is now as follows:

"Comparing the only data available, the team estimate that ten times more fires are happening than are being reported. Instead of an average of 11.7 fires each year, which is what is reported publicly, the researchers estimate that more than 117 separate fires are breaking out in turbines annually."

b. Regarding the line, "Reports of fires in wind farms are increasing, say the researchers.":The Imperial author and the press office accept that readers would benefit from additional context to this statement. While the number of reports of fires is increasing, as there is growth in the number of wind turbines installed, the paper states that the ratio of fire accidents per turbine has decreased significantly.

Therefore the updated version of this section of the News Release is now as follows:

"The number of wind turbines installed grew three-fold between 2007-2012 and the instances of reported fires in wind farms are increasing, say the researchers. However, the ratio of fire accidents per turbine installed has decreased significantly since 2002."

We apologise to reporters and news-release subscribers for not making these points clear in the original news release.

Fire is the second leading cause of accidents in wind turbines, after blade failure, according to research out today.

Wind farming is one of the leading industries in the renewable energy sector. However, the industry faces a number of challenges, such as opposition by wind farm lobbyists. Today's research suggests that incidents of wind turbines catching fire are a problem that is not currently being fully reported.

Researchers from Imperial College London, the University of Edinburgh and SP Technical Research Institute of Sweden carried out a global assessment of the world's wind farms, which in total contain an estimated 200,000 turbines. Comparing the only data available, the team estimate that ten times more fires are happening than are being reported. Instead of an average of 11.7 fires each year, which is what is reported publicly, the researchers estimate that more than 117 separate fires are breaking out in turbines annually.

By comparison with other energy industries, fire accidents are much less frequent in wind turbines than other sectors such as oil and gas, which globally has thousands of fire accidents per year. However, fire accidents can have a considerable economic impact on the wind farm industry, say the team. Each wind turbine costs in excess of £2 million and generates an estimated income of more than £500,000 per year. Any loss or downtime of these valuable assets makes the industry less viable and productive.

The researchers make a number of recommendations to reduce fire incidents in wind farms.

Dr Guillermo Rein, from the Department of Mechanical Engineering at Imperial College London, says: "Wind turbines are viable sources of renewable energy that can assist the world to reduce emissions and help wean us off fossil fuels. However, 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. Our research outlines a number of strategies that can be adopted by the industry to make these turbines safer and more fire resistant in the future."

Wind turbines catch fire because highly flammable materials such as hydraulic oil and plastics are in close proximity to machinery and electrical wires. These 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. Once ignited, the chances of fighting the blaze are slim due to the height of the wind turbine and the remote locations that they are often in.

Since the 1980s, when wind farms were first constructed, the team found that fire has accounted for 10 to 30 per cent of reported turbine accidents. In 90 per cent of the cases, the fire either leads to substantial downtime or a total loss of the wind turbine, resulting in economic losses.

The researchers also outline the main causes of fire ignition in wind turbines in the study. They are, in decreasing order of importance: lightning strike, electrical malfunction, mechanical failure, and errors with maintenance.

The number of wind turbines installed grew three-fold between 2007-2012 and the instances of reported fires in wind farms are increasing, say the researchers. However, the ratio of fire accidents per turbine installed has decreased significantly since 2002.

According to the researchers, the true extent of these fires has been hard to assess because of the poor statistical records of wind turbine fires. In an effort to get a clearer picture about the true extent of fires in wind farms, the team carried out an extensive analysis of data from a wide range of sources. This included Government reports, data from anti- wind farm lobbyists and information gathered by major newspaper investigations.

The researchers suggest a number of measures that can be put in place to prevent fires from happening. These include "passive" fire protection measures such as installing comprehensive lightning protection systems.

Other measures include using non-combustible hydraulic and lubricant oils and building heat barriers to protect combustible materials. Manufacturers are also advised to avoid using combustible insulating materials and apply new monitoring systems to constantly check the condition of machinery so that maintenance work can be carried out in a timely way.

The researchers also suggest a number of "active" fire protection measures that can be used to stop a fire before it takes hold or gets out of control. These include smoke alarm systems inside the turbine, so that fire safety authorities can be alerted rapidly. The team also suggest suppression systems that quickly douse the flames in water or foam.

In the future, the team aim to study the impact of fire in other renewable energy technologies such as solar panels.

The research has been published in the journal Fire Safety Science.

Colin Smith

Senior Research Media Officer - Faculty of Engineering Communications and Public Affairs Imperial College London South Kensington Campus London SW7 2AZ

Tel: +44 (0)20 7594 6712

Email: cd.smith@imperial.ac.uk

Duty press officer mobile: +44 (0)7803 886248

1. "Overview of Problems and Solutions in Fire Protection Engineering of Wind Turbines"

SOLOMON UADIALE [1], ÉVI URBÁN [1], RICKY CARVEL [1], DAVID LANGE [2], and GUILLERMO REIN [3] [1] School of Engineering, University of Edinburgh, UK [2] SP Technical Research Institute of Sweden, Sweden [3] Department of Mechanical Engineering, Imperial College London

2. About Imperial College London

Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.