Mobile building stores wind turbine parts for Siemens

As the components are often very large, this logistical effort results in enormous costs. Siemens Service Wind Power has opted for a different solution: the leading manufacturer of wind turbine generators has teamed up with temporary building manufacturer Herchenbach to develop a semi-permanent warehouse for repairs and maintenance works on site.

Previously, when a repair became necessary, the damaged large parts of wind turbine generators had to be transported to workshops as special heavy loads, in most cases involving long trips from the respective wind farm sites. Each heavy load had to be registered with the relevant local authority and was only allowed to be transported at night. “The wind turbine generators stand idle until the repaired parts are returned,” Mark Borkenhagen, project manager at Siemens Service Wind Power explains. “And each hour of downtime causes significant losses.”

Siemens Service Wind Power therefore started looking for an alternative – and hit on the idea of installing a temporary building for repairs on the actual wind farm sites. A key goal was to avoid the expensive and time-consuming transportation of heavy loads. 

Also, Siemens wanted to be able to use the new semi-permanent warehouse solution throughout Europe, i.e. it had to be possible to install and dismantle the building quickly to be able to rotate from wind farm to wind farm as required.

The warehouse also had to be able to withstand extreme wind loads and be big enough to house the – sometimes huge – turbine parts as well as the repair equipment.

“Wind turbine generators have a diameter of over four metres, measure three metres in height and weigh 80 tonnes,” adds Borkenhagen. “Such dimensions do not fit into any standard temporary building. What was required was a special solution.”

Siemens chose Herchenbach Industrie-Zeltebau, a manufacturer of temporary buildings and semi-permanent warehouses made from aluminium, as the partner for this challenge. Other divisions of Siemens had already worked successfully with Herchenbach on several occasions in the past. The result of this new project is a special Herchenbach Heba-Fix temporary building, ten metres wide and 15 metres long, with an eave height (side height) of 6.40 metres.

Lowered through the roof

The main design challenge was the question of how to get the wind turbine parts into the building as they would not fit through the side walls of a temporary building due to their massive size. Siemens Wind Power had initially intended to build the temporary warehouse around the generators for each repair. “However, this would have been very time-consuming, thus unnecessarily prolonging the downtimes again,” Borkenhagen explains. In addition, the complexity and vulnerability of assembling a building around such a large main component is a risk. Herchenbach therefore developed a special temporary building solution. The basis is a  corrosion-free premium quality aluminium frame and a combination of high-quality PVC industrial-grade tarpaulin in the roof as well as trapezoidal sheet metal and tarpaulin walls. This allows the roof to be partially opened up, meaning that the parts to be repaired can be lowered into the building through the roof opening with the aid of a crane.

Technically, the this involves pulling a part of the roof tarpaulin out of the aluminium frame, a task that can be performed manually without great effort by three to four employees. However, the frame and the components had to be planned and designed with particular precision for this purpose. “Even when the roof tarpaulin is temporarily removed, the structure has to remain stable in spite of high wind loads,” stresses Tobias Raeber, Managing Director of Herchenbach. “We therefore incorporated robust steel trapezoidal sheet metal walls and further reinforcements into the lateral middle sections of the temporary building, at the point where the roof tarpaulin can be pulled out. These provide additional stability, making the building withstand high loads.”

A further advantage of the Herchenbach temporary buildings is that they can be installed without any foundation on almost any surface. This is a crucial factor, particularly at wind farms, which often only have simple compacted gravel surfaces or smaller asphalted parking areas available. This is made possible by the comparatively lightweight aluminium frame of the building (in contrast to steel) and a special ground anchoring solution: during installation of the structure, steel base plates are fixed to the ground at regular intervals by driving nine earth pins up to 1.30 metres into the ground through each plate.

Europe-wide use

In addition, temporary buildings from Herchenbach are ideally suited to temporary use at different locations thanks to their modular design. “All components are bolted or fitted together, nothing is permanently welded,” Tobias Raeber explains. “This means that the buildings can be quickly dismantled at any time and put up again at other locations.” And hardly any spare parts are needed.

This approach has already proved itself in practice. The temporary building supplied to Siemens Service Wind Power was installed for the first time – within 24 hours – in autumn 2015 in the Picardie region of northern France. After four repairs, it was de-installed. The building was then put into storage until its next use in January 2016 in Tinglev, Denmark. “Here, too, the installation went smoothly,” says Mark Borkenhagen. The structure will remain in place in Denmark until it is needed at another location. “We have therefore achieved our objective of rotating the new temporary building around the various wind farms in Europe. And that really does work without too much time-consumption, and our costs are a fraction of what they were with the old method of transporting heavy loads,” Borkenhagen adds.

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