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Foundation Created for Offshore Wind Turbines


Bard Engineering GmbH


North Sea (100km NW German island of Borkum)


Wind turbine manufacturer Bard Engineering GmbH developed a unique concept for the foundations of wind turbines. The mast would be placed on a supporting cross piece that rests above the water surface on three main pilings. The Enerpac synchronous lifting system would be used to level this supporting cross piece accurately and in just a short time frame. Challenge: The 90m high wind turbine rests on three main pilings that are each 90m in length. Above the water surface, these three pilings are connected to each other by a cross piece on which the turbine mast stands. “One of the unique things [about] our foundation is that this part and all connections are above the water surface,” says Robert Ebert, Deputy Managing Director at Bard Building GmbH & Co. KG. “The mast usually rests on foundations that are below the water surface. We chose to have all installation activities performed above the water surface. The practical advantages are that we need fewer divers, that we are less dependent on weather conditions and that it allows us to carry out maintenance much more quickly and easily.” The connection flanges aren't always straight and manual correction to the millimeter of any flange deviations turned out to be impossible. That is why we looked for options for installing the 500-ton support construction quickly and accurately.

Cylinders are connected to the computer of the synchronous lifting system on board the ‘Wind Lift I’, which levels the supporting cross piece.


Enerpac’s Synchronous Hydraulic Lifting System is used to create a support for offshore wind turbines with impressive precision and timing.

Enerpac would provide the solution for leveling the supporting cross piece with synchronously controlled hydraulic cylinders. The installation process was controlled using Enerpac’s computer system, utilizing stroke sensors and an inclination meter. Once the supporting cross piece was level, it was locked in place together with piles by a 5m high concrete casing, with concrete being poured into a hollow space to make a 13cm thick ring against the wall of both the supporting cross piece and the piles. Enerpac also trained Bard employees who would be working with the Synchronous Lifting System. “The nice thing about this hydraulic Synchronous Lifting System is that it works completely automatically. Human errors when leveling manually, such as turning on the wrong valve are totally eliminated by the system,” concluded Robert Ebert.