OREANDA-NEWS. RWE Innogy has commissioned Dutch company Fabricom Offshore Services BV to maintain the foundations of the Nordsee Ost offshore wind farm over the coming four years. The contract includes the inspection and maintenance of the 49 jacket foundations of the wind turbines and the transformer substation, together with the monopile foundations of the measurement mast. The maintenance work will be carried out from the island of Heligoland commencing in summer 2014. RWE Innogy is currently constructing a two-storey operations and maintenance base there, together with a control room from which the Nordsee Ost offshore wind farm will be managed.

“The cost of maintaining foundations and wind turbines at sea is high because the stresses caused by waves and salt water are significantly higher at sea than on land. A good downstream logistics network and, in particular, expert service engineers are therefore a key requirement for ensuring reliable and cost-effective operations at sea”, explains Marcel Sunier, project director for the Nordsee Ost wind farm at RWE Innogy. “In Fabricom we are pleased to have found an expert partner for our first wind farm off the German coast”.

With a proactive approach to maintenance, the partners intend to ensure a high level of operational reliability and availability throughout the entire lifecycle of the Nordsee Ost offshore wind farm.

Stanley Maas, CEO Fabricom Offshore Services BV: “Contributing to the sustainable development of renewable energy sources in a manner that is safe for both people and the environment has become a matter of priority for our company. For this reason we are very proud that this long-term maintenance contract has been awarded to Fabricom Offshore Services, which is in line with our chosen strategy to develop ourselves into a maintenance partner for the offshore wind industry.”

Inspection of a foundation structure at Nordsee Ost offshore wind farm

The last of the overall 49 foundations for the Nordsee Ost offshore wind farm were successfully installed during mid-March, some 35 kilometres north of the island of Heligoland. A total of 48 jacket foundations for the wind turbines plus one for the transformer substation were constructed in water depths of up to 25 metres. Each of the wind turbine foundations is approx. 50 metres in height and weighs some 550 tonnes. Installation of the wind turbines themselves will commence in May followed in the summer by the transformer substation at sea. The first maintenance tasks on the foundations will be carried out in parallel. The stability of the foundations and ensuring safe access to them are key priorities. Inspections will therefore be carried out both above and below the water: Trained height worker inspectors will make above water visual inspections of the structure including the anti-corrosion coating, alongside tests of the welding and bolted connections. Special submarines are used for the underwater inspections. Depending on requirements the inspections of a foundation usually take one to three days per year, though unforeseeable occurrences can cause extra maintenance work.

Once complete in spring 2015, the Nordsee Ost offshore wind farm will have an installed capacity of some 295 MW, which is sufficient for supplying some 300,000 households with electricity each year. Equipped with what are currently the highest output offshore turbines available, the Nordsee Ost offshore wind farm is among the largest commercial wind power projects off the German coast.