OREANDA-NEWS. The last few days have been challenging for the installation teams of RWE's offshore wind farms. The last of the 160 wind turbines has now been installed successfully off the Welsh coast, and cabling and commissioning works continue at pace to ensure the wind farm becomes fully operational this winter. The construction of the German RWE sister project Nordsee Ost, too, reached an important milestone: The first of altogether 48 wind turbines was erected successfully about 30 kilometres north of the island of Heligoland.

“The first turbine for our Nordsee Ost wind farm stands in the water,” explained Marcel Sunier, project director for the Nordsee Ost wind farm at RWE Innogy. “The rotor blades of the 6-megawatt system of the company Senvion were for the first time not installed as preassembled rotor spider, but all rotor blades were fitted to the hub individually at sea. The assembly of individual blades was required due to the navigation restrictions on the river Weser, granting only restricted permission for the installation vessel to navigate with a preassembled rotor spider on board due to its width.”

First turbine installed at Nordsee Ost

The sheer size of the individual components of the 6-megawatt turbine for the Nordsee Ost wind farm is impressive: With a height of approximately 160 metres from the sea level to the tip of the blades the wind power system is higher than Cologne's famous cathedral. The nacelle has a weight of approximately 350 tons and about the size of a single-family home. It houses the mechanical components like transmission and generator. The tower consists of two individual segments, has a total length of 70 metres and a weight of more than 240 tons. Each rotor blade is over 60 metres long and weighs approximately 23 tons. This is equivalent to the weight of about six grown-up elephants.

“The construction of the Nordsee Ost wind farm is making good progress”, Sunier emphasised. “All the foundations have been firmly anchored in the sea bed since mid-March, this month we completed the array cabling, and in the last few weeks we installed ten towers, nacelles and hubs. The offshore substation is due to be erected in the weeks ahead. We are therefore absolutely on track for the complete commissioning next spring.”

First turbine installed at Nordsee Ost

Gwynt y Mor's turbine installation programme was carried out from the Port of Mostyn in North Wales, with components - turbine towers in two sections, nacelles, hubs and blades - arriving from Siemens' factory in Brande, Denmark. Toby Edmond, project director for Gwynt y Mфr at RWE Innogy, explains: “The first of the 160 turbines was installed in May 2013, with the hundredth constructed offshore at the end of November that same year. To have achieved the installation of all 160 in just over a year is a credit to the excellent cooperation between our project team, A2SEA and Siemens. Our focus now turns to completing array cabling and commissioning all turbines to ensure the wind farm is fully operational over the winter.”