Wind turbines are a recent arrival on the landscape over the last 30-40 years, and during their short stay the structures themselves, and the industry which supports them, have acquired a benign, friendly reputation. In 2013, events in the small Dutch town of Ooltgensplaat challenged those perceptions. As the result of a short-circuit, four young engineers servicing a wind turbine became trapped by fire, and two of them lost their lives.
The situation was unusual but not unprecedented. A 2014 joint study by Imperial College London, Edinburgh University and Sweden’s SP Technical Research Institute identified fire as the second-largest cause of incidents in wind turbines after blade failure. Fatalities like those at Ooltgensplaat are mercifully rare, but anecdotal evidence suggests that consequential losses from such fires tend to be large — mainly because the turbines are sited offshore or in deep countryside, making firefighting difficult.
It’s surprisingly hard to assay those losses. The UK government does not maintain a database on the subject, and insurance companies are only obliged to publish a minority of case details. The most reliable statistics are those provided by the Norwegian-based registrar DNV GL (Det Norske Veritas Germanischer Lloyd), which cites 0.5 fires per 1000 turbines per year globally.
Informal data from the Caithness Windfarm Information Forum tends to support the DNV GL figures. The Forum recorded an average of 49 accidents per year from 2000-2004; 109 accidents per year from 2005-2009; 163 accidents per year from 2010-2014 inclusive, and 210 accidents per year from 2015-2019 inclusive. Those figures are broadly in line with the spread of windfarms.
Prevention and cure
Turbine fires can start through human error, electrical failure, or as the result of that old favourite, lightning strikes. Maintenance operations are generally considered to be the riskiest time, with hot-tool and hot-surface processes highest on the list of fire hazards. (Cooking also figured in a number of incidents.)
Once ignited, fire can spread throughout turbine machinery via highly-combustible lubricating and transformer oils and the composite materials found in the turbine blades, the nacelle walls and the low-speed shaft.
Given the difficulty of fighting wind turbine fires, it’s no surprise that fire prevention is high on the priority list for manufacturers. They tend to favour the use of non-flammable materials and a range of passive fire protection methods which includes compartmentalized (‘bulkheaded’) designs, non-combustible insulations, and the incorporation of intumescent materials which expand at high temperatures.
Fire-resistant hydraulic fluids and lubricant oils are also favoured by both manufacturers and operating companies.
Active fire protection systems including automatic gas; often SF6; aerosol, water and powder suppression systems and audible and online alarms also have parts to play. However, it is important to note that automatic suppression mechanisms may cause serious injury if they are deployed while personnel are at work on the turbine.
Portable fire extinguishers — ideally of the maintenance-free type — figure in most turbine inventories, although the G9 Offshore Wind Health & Safety Association states that ‘a fire extinguisher should be considered as an aid to escape rather than a primary means of fire control.’
Training is critical
But most critical of all is the provision of detailed fire safety plans. These should be developed in collaboration with the relevant rescue services and backed up with appropriate training.
At Safer at Work, our GWO-accredited Fire Awareness Course will equip you with the skills and knowledge needed to minimise fire risks in wind farm environments, to recognise the onset of a fire and fight it safely, and to make effective contingency plans for managing fires… up to and including evacuation.
Contact us today to learn more about our GWO Fire Awareness course and available dates.