Massive damage in the wind farm - cause unclear

The damage at the offshore wind farm, "Alpha Ventus", located about 45 kilometers from Borkum, is considerably more serious than initially known. At the beginning of April not only did the plastic covering of the nacelle crash 90 meters into the sea, but half of the nacelle itself fell off as well. Experts are now investigating whether it is a single incident or possibly serial damage. More than 120 turbines of this type are installed in the North Sea.

You can no longer speak of "teething troubles"

At least half of the wind turbine "AV07" is missing. Such massive damage has never been witnessed in the North and Baltic Sea. So far, the operator EWE has always presented itself as a pioneer with the first German offshore park "Alpha Ventus". Although the first problems with the systems appeared shortly after commissioning in 2010, EWE spokesman Christian Bartsch admits: "These are very early models in which we have had to replace components in recent years." At that time people liked to talk about "teething troubles". This time the case is completely different, there is nothing to gloss over. The managing director of the wind energy association WAB, Andreas Wellbrock, is not just worried about the image of eco-energy. He sees the failure as a setback. 

Do other wind farms have to be shut down?

The nacelle of an offshore wind turbine is as big as a family home, with plenty of space for the gearbox, generator and other technology. In front of it sits the so-called rotor star. To protect the sensitive equipment from corrosion, the Bremerhaven-based manufacturer Adwen relies on a special system which creates a slight overpressure in the nacelle to prevent the salty ambient air from entering. It is possible that a steel support frame which carries the plastic cover of the nacelle rusted through. Immediately after the failure, all access to the facilities was blocked. Until the cause is known, service technicians are not allowed to go up. This not only applies to the defective "AV07" turbine at the "Alpha Ventus" park, but to all identical models. More than 120 turbines are installed in two other offshore parks in the North Sea: "Global Tech 1" and "Trianel Borkum". These units are currently still operating while "Alpha Ventus" is offline. The longer Alpha Ventus is offline, the greater the risk that the other two wind facilities may be shut down as well. If routine maintenance and minor repairs can not be performed at "Global Tech 1" and "Trianel Borkum", the equipment will have to shut down.

"No evidence of specific vulnerabilities"

A complete nacelle failure seems very unlikely and an expert at the Federal Maritime and Hydrographic Agency (BSH) is demanding an explanation. The BSH is responsible for the approval and safety of offshore wind farms. So far, such a life-threatening failure had never been contemplated. Related questions from Manfred Zeiler of the BSH suggest he does not like the answers he's getting. "In the case of 'Alpha Ventus' we receive corresponding test reports every year. There have been no indications of any particular weak points, no special occurrences, the plant was inspected two years ago, there were no abnormalities that could give any indication of such a claim." Apparently, the authority has to change the test criteria.

Manufacturers usually exchange nacelles rather unobtrusively

The Oldenburg energy provider EWE, which operates "Alpha Ventus", believes that the manufacturer, Adwen, has the obligation to repair the turbine under the existing maintenance and repair contract. Adwen was formerly known as Multibrid, then Areva, and was later sold again and now belongs to Siemens and Spanish Gamesa. Adwen's Bremerhaven offices now just performs maintenance and repair for the company. When total nacelles are replaced, this is handled by Adwen as discreetly as possible. Offshore wind power is a billion dollar business. If something goes wrong, it happens without any attention or publicity. This was not the case this time. Andreas Wellbrock of the WAB sees the failure as already causing "capital damage."

Insiders advise to replace the system

The investigation into the cause of the failure is ongoing. EWE spokesman, Bartsch, assumes that the damaged system will be repaired while insiders think that is out of the question. They advise the full replacement of the nacelle.

Translation into English assisted using Google Translate.