International Dredging Review

International Dredging Review
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Situated 85 kilometers (about 52 miles) north of the coast of the Dutch province of Groningen four project partners have joined forces in the construction of the Gemini Project. These are: Canadian independent renew-able energy company Northland Power (60 percent project interest) wind turbine manufacturer Siemens Wind Power (20 percent) the Dutch maritime contractor Van Oord (10 percent) and renewable energy and waste processing company HVC (10 percent). Officially Gemini is being built on two locations close to each other Buitengaats and Zee-energie hence the name Gemini the Latin word for twins. In order to install each windmill Van Oord’s flexible fallpipe vessel FFPV Stornes – which can carry 26000 tons of protective material – is placing 2000 tons of material on the seabed at the site where each monopile will be driven into the seabed. To prevent erosion around the monopile the bed of stones is 1.5 meters (almost five feet) thick and has a diameter of about 30 meters (98 feet).

To install the monopiles and transition pieces as well as the towers and blades later on in the project Van Oord’s new offshore installation ship Aeolus has been deployed. The Aeolus stands on four legs above the water level and can work in water to a depth of 55 meters (180 feet). It is able to install three monopolies and transition pieces at one go before it must return to port to pick up new material. In addition Van Oord has deployed its new cable-laying vessel Nexus. 

Van Oord is the EPC (Engineering-Procurement-Construction) contractor for the Gemini offshore wind farm which will be one of the largest off-shore wind projects in the world. Van Oord’s activities include the supply and installation of the foundations the entire electrical infrastructure including the supply and installation of offshore and onshore high voltage stations inter-array and export cables and the installation of 150 4 megawatt (MW) Siemens wind turbines. These will supply a total of 600 MW of renewable energy to 785000 households by 2017. Van Oord’s part of the contract is valued at more than €1.3 billion the largest contract in the company’s history. 

Another energy supplier E.ON has awarded Van Oord the contract for the transport and installation of foundations at the Arkona offshore wind project located in the German Baltic Sea. Van Oord will install 60 monopiles and transition piece foundations. For installing foundations at the Arkona offshore wind project Van Oord intends to deploy its heavy lift installation vessel Svanen. The feeder concept is being used i.e. floating foundation components to the Svanen at the installation site. The Svanen has previously installed more than 500 monopiles using this method. The installation works are planned for 2017. With an installed capacity of 385 MW the Arkona offshore wind project will be located more than 35 kilometers (21 miles) North of Rügen Island Germany and will be able to supply renewable energy to 400000 households. E.ON will have responsibility for building and operating the wind farm. The energy company Statoil will have a 50-percent stake and be involved in the project from the start.