Three phases can be roughly recognised in the service life of a wind turbine: newer turbines (0-10 years), medium-aged turbines (10-20 years) and older turbines (20+ years). While manufacturers generally take over maintenance for new installations, DWT is often responsible for ensuring smooth operation of not-so-new, medium-aged and, in some cases, older turbines. "Even though manufacturers and independent providers compete with each other in the service market, we are aware that providing maintenance as a whole is a common challenge for the entire wind industry," said Matthias Brandt, Director of Deutsche Windtechnik AG. "You need a diverse range of market participants to keep the many wind turbines operating at a high level of performance, not only in terms of quality but also quantity. The wind industry, and in our case the service industry in particular, is in the midst of the energy transition, which will result in the addition of many more turbines. We therefore see ourselves as collaborators with a common goal of making wind energy successful in the long term," said Matthias Brandt.
Hauke Behrends, Managing Director of Deutsche Windtechnik GmbH & Co. KG, said: "Of course, we also see competitive situations with the OEMs, but we also want to emphasise that there is a great deal of cooperation in day-to-day business. There are numerous projects where we help each other, explicitly in both directions. This includes the supply of parts, communication of HSE information, acceptance of repair orders and much more."
Does maintenance differ depending on age?
In principle, there is little difference between the scheduled maintenance of new, medium-aged and older turbines: For all turbines, it is carried out in accordance with the maintenance specifications provided by the manufacturer. It usually takes place at six-month or annual intervals. The main challenge when servicing older turbines is the supply of spare parts. Hauke Behrends said: "Some OEMs as well as some makers of components for these types of turbines are increasingly losing sight of the maintenance of older turbines and are phasing out the production of spare parts. This used to present us at DWT with repeated challenges when it came to repairs." By now, DWT has developed repair processes for various core components and opened up corresponding capacities with which a large number of frequently defective components can be refurbished. More than 30 percent of spare parts are now reconditioned in a closed-loop process in accordance with industrial standards. This ranges from central power electronics components to large components such as gearboxes and generators. However, intact rotor blades from dismantled turbines are also stored temporarily, just in case. "All of this is also a sensible approach in terms of sustainability. And to bring in the topic of the energy transition: All of these measures have a significant impact on the productivity and service life of medium-aged and older wind turbines and therefore on the wind industry's contribution to the energy transition."
Service lives of more than twenty years are becoming the rule
The statistics do not suggest that medium-aged or older types of turbine will soon be obsolete and that their spare parts will no longer be needed. On the contrary: In the past, it was assumed that a turbine would have a service life of twenty years, but it is now clear that many turbine technologies can realistically be operated for many more years. In its report Status of Onshore Wind Energy Expansion in 2024, the German Wind Energy Association states that the number of turbines decommissioned in recent years correlates more with the development of repowering. This would lead to the conclusion that old turbines were mainly decommissioned to be replaced by new turbines. The average age of the wind turbines decommissioned in 2024 was 22.6 years of operation, according to the report. Of the installed wind energy capacity at the end of 2024,18 percent have been in operation for more than twenty years. A further 14 percent have been connected to the grid for fifteen to twenty years. One fifth of the wind energy capacity installed nationwide is ten to fifteen years old, and slightly less than half (47 %) of the installed generation capacity has been in operation for less than ten years.
OEMs and independent providers have a common goal
This is in line with the relevance of increasing cost pressure for the growing number of medium-aged turbines: The fixed EEG feed-in tariff is expiring, operation must be economically optimised and legal requirements are constantly being added, such as continued operation inspections or safety certificates. Matthias Brandt said: "Our aim is to ensure that the turbines are operated economically at all times, whether until repowering takes place, or as part of continued operation beyond twenty years. In our view, the success of the energy transition requires good service in addition to the development and installation of high-performance turbines: Whether through OEM service or independent service providers, old or new technology – we will only be able to keep the existing and future turbines running safely and efficiently by working together."
Source: “Status des Windenergieausbaus an Land Jahr 2024“ vom Bundesverband Windenergie (= German Wind Energy Association)
