COMPANY PROFILE
2014
Butendiek Offshore Windfarm
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Green power for 360,000 homes Editorial Tim Hands
Situated 32 kilometres west of the island of Sylt, in the North Sea area of Germany, construction of the 288MW Butendiek Offshore Wind Farm is scheduled to be completed in June 2015. The 1.3 billion Euro project is expected to generate 1,290 Gwh of power annually, to serve 360,000 households.
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Covering an area of 42 km2 in the German Exclusive Economic Zone Water of the North Sea, near the Danish-German border, ownership of the project is equally split between its five powerful partners. Siemens Financial Services, Marguerite Fund, Industriens Pension and PKA each hold a stake of 22.5%, while WPD, the developer of the project, owns the remaining ten percent. It was after acquiring 100 percent of the Butendiek Offshore Windpark Holding from SSE Renewables, in September 2010, that the WPD group began the development of
Butendiek Offshore Windfarm the project. Negotiations on the design, production, delivery and installation of the project, as well as the necessary major supply contracts, were all completed and secured by September 2011, with its implementation made wholly more concrete in February 2013. An agreement reached at this time means that the project will be financed through 67% debt and 33% equity, with the debt financing of the project to be provided by a consortium led by UniCredit, KfW Ipex and Bremer Landesbank. A consortium of lenders, comprising the European Investment Bank (EIB), KfW Förderbank, Denmark’s Eksport Kredit and nine other commercial banks, are providing €937m of loans to the Butendiek project, which is backed up by equity
funding from Siemens Financial Services, Marguerite Fund, Industriens Pension, PKA and WPD. From the beginning of its working life in 2015, the park will generate clean power for a period spanning, at the very least, 25 years.
HIGH-TECH POWER From its expansive site, the Butendiek Offshore Wind Farm’s 80 wind turbine generators of the 3.6 MW class will combine to produce green electricity for nearly half a million households. It is a project of impressive scale throughout – the turbines themselves reach heights of 150 metres above sea level, while their rotor boasts a diameter of 120 metres, a good deal larger than the world’s current biggest airliner.
These turbines will be mounted on tapered tubular steel towers, with the site’s water depths of between 18 and 22 metres ideal to support the wind turbines on monopiles, with Ballast Nedam’s Heavy Lift Vessel (HLV) Svanen to be used for installing all of the foundations. The other components of these complex constructions include a microprocessor-based wind turbine controller, a 3,600kW asynchronous generator and a three-stage planetary / helical gear box, while the variable speed of the rotor will maximise aerodynamic efficiency. The precise, carefully-chosen location of the wind farm is noteworthy not only for its attractive wind resources, but also the ideal soil conditions present,
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as summed up by Achim Berge Olsen, managing director of wpd offshore: “With its favourable site conditions including wind resources, water depth and distance to coast, Butendiek is one of the most attractive offshore wind projects in the German North Sea and it will now be implemented with a strong international group of investors under the leadership of one of Germany’s most experienced teams.” One of the most complex constructions of the whole wind park, it is in the offshore substation where the power generated by the colossal wind turbines is to be collected, whose platform will be delivered by Fabricom GDF Suez JV of Belgium. Its foundation structure is anchored to the seabed by four steel piles, with a topside equipped with transformers and high voltage components. Here, the conversion from medium voltage to high voltage power takes place, thus creating the
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“With its favourable site conditions including wind resources, water depth and distance to coast, Butendiek is one of the most attractive offshore wind projects in the German North Sea and it will now be implemented with a strong international group of investors under the leadership of one of Germany’s most experienced teams
requisite conditions to then feed it into the high voltage grid. The Butendiek substation is linked to the converter platform SylWIn Alpha via a submarine cable 38 kilometres in length, from which point the power is transferred along 160 kilometres of the same cabling to the mainland and the Converter Station Brunsbuttel. The connection of the wind farm with the grid, through the SylCluster, will be undertaken by Dutch-German transmission grid operator TenneT TSO, while the inter-array cabling of the project will be provided by Visser Smit Marine Contractor, a company based in the Netherlands. Working towards its commissioning in October of this year, March of 2014 saw the start of offshore construction at the project’s site, with the installation of the filter layer which, with its diameter of approximately 35 metres and consisting of gravel and sand, prevents the soil at the foundation from scouring.
Butendiek Offshore Windfarm This was then followed in April by the two part installation of the offshore substation, with both parts transported and installed by heavy lift vessel Rambiz. Firstly, in an installation of this kind, the jacket foundation is put on the ground and anchored in the seabed with four piles, to which the topside is then welded. Most recently, in June, the loading into its complex predetermined sequence of the wind farm cables took place. These are laid section by section between the foundations with the ends pulled into the monopiles, before the cable is then buried in the ground. Up next on this complex construction timeline comes the installation of the offshore turbines themselves, project to take place in September of this year. The installation vessel Bold
Tern will set sail with eight sets of turbines from the installation harbour, all the way to the project site, and install the turbine in five steps; beginning with the tower, the nacelle will follow and, finally, the three rotor blades will see it completed and ready to generate. The completion, in May, of the installation of arguably the jewel in Butendiek’s crown, the offshore substation, represented the reaching of one of the project’s most important milestones. In order for the substation’s topside to be mounted onto the jacket foundation the platform had to shipped on a pontoon from the production yard in Antwerpen, to the Danish port of Esbjerg. A short stopover was necessary before it could continue its journey to the construction area, where the heavy lift vessel
Rambiz was again called into action, fortuitously already positioned after installation of the jacket foundation. Following an operation spanning nearly an entire day, the platform, weighing 2,300 tons, having been heaved in the afternoon, was finally lifted into its resting place late that evening.
WELL OILED PARTNERSHIPS The building and installation of this substation is undertaken by a consortium of four companies: Cofely Fabricom GDF Suez, which is responsible for the design, electrics and auxiliary systems, while Iemants N.V took responsibility for the steel construction. CG Holdings Belgium N.V has overseen the design, supply and installation of this high voltage substation,
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Safe transfer of personnel from service vessel
Emergency response rescue & Standby duties
Gangway and boat solutions
Workshop
Offshore accommodation
Spare part storage facilities
alongside all major electrical components, and GeoSea complete the consortium by taking care of its installation. Based on a jacket foundation, the top side of the substation contains four decks which are designed to house the two 33/155 kV transformers, each of a rated power of 288 kVA, as well as the core high voltage equipment on the main deck. On the lower deck the internal cables from the wind turbines and the Tennet cables are installed for connection to the switchgear. Additionally, on the lower deck, diesel generator sets and two large tanks for water and diesel are installed. The control and communication systems, office and accommodation rooms are located on the mezzanine deck, while to cap off the apparatus
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“We are about to complete pile driving, we are well within our time schedule and we have fallen short of the predefined sound levels”
the top deck harbours the crane, antennas and the helicopter landing platform. The most recent interim report for Butendiek displayed incredibly positive results, ecologically as well as logistically, as Achim Berge Olsen describes: “We are about to complete pile driving, we are well within our time schedule and we have fallen short of the predefined sound levels.” These sound levels are in fact the lowest ever measured during this task of pile driving, with the analysis of the data amassed from the accompanying ecological monitoring showing no measurable differences in the population of the common porpoise in the surroundings of the offshore wind farm Butendiek. “Analysis of the data shows
Butendiek Offshore Windfarm
that the common porpoise is still present in the surroundings of the construction site, furthermore there was no evidence as to a decrease in the population. For us, this means that our elaborate and cost-intensive sound protection measurements are effective and working,” states Olsen, and such measures exemplify the commitment to environmental concerns demonstrated through all stages of this project. Noise mitigation has been of utmost priority, given the location within a nature protection area, with various methods employed to protect the marine mammals. These have ranged from using a seal scarer and pinger shortly before pile driving, in order to gently prompt marine mammals to vacate the area of construction in good time, to
employing a ‘big bubble curtain’ to surround the jacket foundation of the offshore substation, to ensure that compressed air is pushed through small holes in the hose and rises as bubbles up to the sea level. The North Sea is widely recognised to house a very unique environment, and one which thus needs to be handled with the utmost care during any economic activity. For the Butendiek project area, this took the form of compulsory environmental investigations of potential ecological impacts the project may have, with a central focus on the wildlife most likely to be affected, among them benthos, fish, resting and migrating birds and marine mammals. Conducted during the planning phase over a period of three years, an
extensive Environmental Impact Assessment comprised different aspects according to each species concerned, and included monthly and seasonal investigations by ship and aeroplane, while, going above and beyond the demands of the authorities, a continuous monitoring of marine mammals with stationary porpoise detectors close to the project area of the Butendiek wind farm was also carried out. Not merely a box-ticking exercise, these investigations are set to be an integral part of both construction and operation of the wind farm, ensuring a continuing commitment to the ecology of the vast site, all while generating the huge amount of green power of which the farm is capable for an ever growing number of households
Offshore Design Consultancy and Project Management OUR CORE BUSINESS Oil & Gas Engineering & Fabrication Shipbuilding Ship Repair Naval Craft Building & Maintenance
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