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Germany has its first offshore wind turbine: the consortium of EWE, E.ON and Vattenfall, DOTI (Deutsche Offshore- Testfeld und Infrastruktur GmbH), has successfully completed construction of the first of a total of 12 wind turbines for the alpha ventus offshore wind farm in the North Sea. A team of 50 specialists are on location at the open sea renewable energy construction site. The 5-megawatt turbine is situated 45 kilometres north of the island of Borkum. All 12 turbines are scheduled to be in operation by the end of 2009, making alpha ventus the first offshore wind farm in German waters. 250 millions euros have been invested in this pioneering project. The power produced annually by alpha ventus will meet the energy needs of 50,000 households - promoting green building on a big scale.
"This is a first for offshore wind energy utilisation in Germany" says Wilfried Hube (EWE), overall project leader of alpha ventus. "For the first time, wind turbines of this size are being constructed this far offshore in waters up to 30 meters deep. EWE, E.ON and Vattenfall are accomplishing a truly pioneering feat in the offshore wind industry and I am certain that alpha ventus will be a success story."
The project is managed by a 40-person team of employees from the three companies involved. The joint company DOTI was founded in June 2006; construction work for the building and installation of the wind turbines has been underway since mid-2007. "What the three-company team has achieved since then is more than impressive" says Ralf Lamsbach of E.ON, who also serves as a managing director of DOTI.
"The entire team is working in concert, beyond all boundaries of the individual companies, and shows the absolute will and motivation needed to lead the project to success. The teamwork is clearly the keystone to alpha ventus." In the decision to build alpha ventus, Germany's first offshore wind farm, the three partners are breaking new ground. Although there have been cases of individual companies involved in other European wind projects, the general conditions for alpha ventus have so far been unique.
"This is also reflected in the capital expenditure. The 190 millions euros that we had originally planned was increased to 250 millions euros" says Vattenfall's Oliver Funk, who also acts as a managing director of DOTI. "In this respect, one can already say that we have learned the hard way, but this money has been invested well. In future projects, each individual company involved will profit from the valuable experience gained from alpha ventus."
The next step is the phased launching of the first wind turbine. Also involved is connecting the turbine to the offshore transformer station, which will follow in the coming weeks. EWE will later be responsible for supervision and overall operational management of the newly constructed wind farm. "Here as well we are gathering important experience concerning the future availability and maintenance of the turbines" says Dr. Claus Burkhardt (EWE), who, as a managing director of DOTI, is responsible for the wind farm. "This knowledge will also provide us with further information on the profitability of offshore wind farms."
Enerpac's Lifting System to Raise the Masts
Enerpac’s Synchronous Hydraulic Lifting System was used to create a support for offshore wind turbines with impressive precision and timing.
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.
Application: Cylinders are connected to the computer of the synchronous lifting system on board the ‘Wind Lift I’, which levels the supporting cross piece.
Solution: Enerpac Synchronous Hydraulic Lift System: 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.
The ongoing activities at sea can be followed from a webcam positioned on the research platform FINO1. A link to the webcam.
Alpha Ventus Wind Farm Book (2,808 kb)