There are around 200,000 wind turbines in the world. On average, twelve fires involving these turbines take place annually. It is up to each person to decide if this number is too high or not. However, it is a fact that we all consume electricity every day and electricity production with wind turbines is an efficient and environmentally friendly method.
The fire safety of wind turbines suddenly became a topical issue following a recent fire in Viru-Nigula. Since I am in charge of Eleon, a company that manufactures large wind turbines, and we are in the middle of installing a wind farm in Viru County, I consider it necessary to explain why it is completely out of the question that the new wind turbines will catch fire like this. Although an expert analysis will reveal the specific circumstances, which led to the fire in Viru-Nigula, I will try to shed light on the likely causes of the fire.
All big wind turbines appear to be very similar: at the top of a high, bright tower sits a white nacelle, to which three revolving rotor blades are attached. A wind turbine is a wind turbine, people think. That is in fact not the case, as wind turbines that appear to be quite similar employ a wide range of technologies.
Simply put, multi-megawatt wind turbines can be divided into two types: old-school wind turbines with a gearbox and wind turbines of the new generation that are highly efficient and mainly use direct drive. In the case of old-school wind turbines, three factors cause a fire hazard: both the medium voltage transformer and the power electronics, as they are both up in the nacelle, and the housing of the nacelle because it is made from fibreglass plastic, as well as the oil in the gearbox, which acts as a fuel in the event of a fire. The accident in Viru-Nigula likely became possible owing to a concurrence of these three factors.
The wind turbine in Viru-Nigula likely caught fire as a result of the following sequence of events. The medium voltage transformer installed in the nacelle at the top of the turbine, which is constantly shaken by strong winds, created an arc flame, which resulted in ignition. Oil that gushed out of the transformer caused the fire to spread. As the temperature rose, the fibreglass plastic nacelle also caught fire. Oil that poured out from the gearbox literally added more fuel to the fire.
This particular wind turbine (operated by Nelja Energia AS) was produced by Winwind OY, a Finnish manufacturer that went bankrupt in 2013. The technology used in this turbine is from the 1990s and did not meet either the modern safety or efficiency standards.
According to statistics, more than 80% of fire incidents involving wind turbines have originated from medium voltage transformers installed at the top of the tower. The reason is the fact that the nacelle of a wind turbine is constantly shaken by strong winds, which is a phenomenon that everybody who has flown into turbulence on a plane or been at sea during a storm has experienced.
In the course of time, however, constant shaking creates a situation where each detail that can become loose indeed does become loose. And everybody can guess what happens in a nacelle when a seven-ton transformer that operates at a thousand volts gets loose…
This rare but nonetheless dangerous sequence of events could not possibly unfold in wind turbines that belong to the new generation.
The medium voltage transformer in the new generation Eleon wind turbines developed in Estonia is, however, installed in special rooms on the basement floor separated by a firewall. When any devices catch fire in these rooms, the fire does not spread to the nacelle or other systems of the wind turbine. Additionally, the transformer is not exposed to any vibration or shaking on the basement floor. We do not know of any cases where a nacelle fire originated from the foot of a wind turbine.
The fact that the housing of the nacelle of an Eleon type wind turbine is not made from flammable plastic but from fireproof, two-centimetre-thick steel also increases fire safety by a significant degree. This arrangement prevents fire from moving outside of the wind turbine’s nacelle even if the fire does indeed break loose. Fibreglass plastic blades catching fire, which happened in Viru-Nigula, is also ruled out.
Thirdly, the new generation Eleon wind turbine uses direct drive. In other words, it is without a gearbox, which means that hundreds of litres of gearbox oil cannot be found at the top of the turbine, which would have an explosive effect in the event of a fire. These three upgrades alone increase the fire safety of our new generation wind turbines by a significant degree. Fire in a wind turbine is extremely rare and wind turbines are a safe and environmentally friendly choice compared to other possible sources of energy.
In addition to the higher safety standards of the new wind turbines, I would like to highlight another important aspect for the people of Estonia and, above all, the people of the Viru region – jobs. The production of Eleon wind turbines is currently distributed between several countries. We order over 10,000 components from more than ten countries. Our wish is to gradually make Estonia the centre of the production and assembly of the turbine’s components, thereby creating a completely new branch of industry here.
This planned full-scale wind turbine industry means an export turnover of several hundred million euros for Estonia and the creation of new jobs, predominantly in the counties of Lääne-Viru and Ida-Viru. It is vital that the unfortunate ignition of an old-school wind turbine would not tarnish the reputation of the entire industry.
Alas, accidents do happen. However, one does not need to be fearful of similar accidents happening to the new generation of wind turbines. Hundreds of engineers have worked hard on the development of this new generation of wind turbines to prevent such accidents. Wind turbines present a great opportunity for the residents of the Viru region.
Oleg Sõnajalg (Wind Technology Association, board member; AS Eleon board member)