Offshore wind turbine installation specialist A2Sea has completed its second major wind farm project, putting up 72 turbines at Nysted Havmøllepark between 10 May and 27 July 2003. Completion was 11 days ahead of the 90-day schedule.
Using one of its two specially adapted ship, Ocean Ady, rigged out with a Demag CC 2500 and four spud legs to put down for stability when lifting, A2Sea worked around the clock, transporting turbine components from Nyborg to the windfarm in the Baltic Sea.
The windfarm forms a dotted square of 4km by 4.5km approximately 6km off the south coast of Nysted, which is on the Danish island Lolland.
The turbines stand 110m high and, at 2.3MW each, are expected to generate enough electricity to power 150,000 Danish homes.
The wind farm has been built by the joint owners E2 and DONG from Denmark and Sydkraft of Sweden. Bonus Energy was main contractor and A2Sea’s client.
The early completion for A2Sea came despite having 15 days where wind prevented work proceeding, instead of the eight or 10 that had been planned for.
Each shipment picked up at the harbour in Nyborg comprsied four complete turbines. The tower sections were bolted on to the tank top and decks vertically, standing 36m above sea level, and the rotors were bolted together on top of each other on the aft section of the weather deck. They had a total height of 13m when loaded horizontally and a diameter of 82.5m. This meant that more than 25m of the blades hung over both sides of the vessel.
Sailing to and from the site took approximately 10 hours each way, as did the installation of all four turbines being carried on each trip. This in effect meant that in good weather a turbine could be installed in a total time of less than one day, a rate quicker than what is often achieved onshore, according to A2Sea. A total of 18 round trips from Nyborg to the site were performed and all went smooth and without interruptions, with all components on the pier ready for loading eveyr time Ocean Ady docked.
The Nystad project brings to 154 the total number of turbines installed by A2Sea, including 80 at Horns Reef and two off the coats of Frederikshavn, representing 65% of all turbines so far installed offshore.
This experience, coupled with the fact that no more offshore windfarms are planned in Denmark for the next couple of years, has prompted A2Sea to turn its focus to foreign markets. It has set up offices in the UK, a country where 18 projects are planned, and in Germany. It is also monitoring progress on proposed windfarms off the coasts of Belgium, Holland, Ireland, Sweden and Poland.
