Major contracts awarded for London Array wind farm

In much the same way that new cruise ships claim to be the largest, until the next one comes along, so a number of offshore wind farms are in line to temporarily hold the title of world’s largest but the London Array project, owned by Danish group DONG Energy (50%), Germany’s E.ON (30%) and Abu Dhabi based Masdar (20%) will have a significant lead once completed. If both the two phases of the scheme go ahead the wind farm will comprise of 271 turbines making it the world’s first 1GW offshore wind farm.

Following recent additional support for offshore wind in the UK budget, deals with six contractors worth almost €2bn have been announced covering the 175 turbine, 630MW first phase of the project.

The largest contract at €1bn, signed in May, has been awarded to Siemens Wind Power which is to supply 175 turbines, each rated at 3.6MW and fitted with the new Siemens 120m rotor with a hub height of 87m above sea level. A five year warranty and servicing contract is also included.

A consortium comprising Danish company Per Aarsleff A/S and Germany’s Bilfinger Berger Ingeniuerbeau GmbH has been awarded the contract for the design, supply and installation of 177 monopile foundations comprising 175 turbine and two sub-station foundations plus the installation of the 175 turbines themselves. The monopiles will be up to 60m in length and weigh 500 tons, with the transition pieces up to 30m in length and weighing 400 tons. Planning and production is scheduled for 2009-2010 with installation taking place during 2011 and 2012.

The two offshore sub-stations, each over three levels and weighing 1,400 tons, will be designed, fabricated and installed by Future Energy, a joint venture between Fabricom, Iemants and GeoSea. A heavy lift vessel has been committed for the installation of the sub-stations.

The companies that will carry out the array and export cabling work have also been announced. Nexans Norway AS has won the €100m contract to design, manufacture and supply 220km of 150kV export cable to run from the site to the shore sub-station at Cleve Hill in Kent. Nexan’s factory in Halden, Norway will deliver two of the cables in 2011 and two in 2012. The fibre optic elements of the cable will be supplied by the company’s factory in Rognan, Norway.

Around 210km of 33kV cables connecting the turbines to each other and the offshore sub station will be designed and manufactured in the UK at the Hartlepool factory of JDR Cable Systems, with production scheduled for 2010 and 2011.

Installation of the array and export cables will be carried out by Visser & Smit Marine Contracting and Global Marine Systems. Both companies are no strangers to such work, particularly in the Thames Estuary area. VSMC are involved in the nearby Gunfleet Sands wind farm export cable work and the Britned DC interconnector cable between Maasvlakte in Holland and the Isle of Grain in Kent (see Maritime Journal November 2009). Global Marine Systems, based in Chelmsford UK, has also been involved in the Britned cable project.

Finally, it has been announced that Siemens Transmissions and Distribution Ltd. will undertake the work on the electrical systems on the offshore sub-stations. The company is already involved with similar work at the Cleve Hill onshore sub-station.

Dr. Frank Mastiaux, chief executive of E.ON Climate and Renewables said; ‘Signing these contracts is a significant milestone for the London Array project, which will be a vital scheme as we look to take renewables from being a niche power player to being a significant, vital part of the UK’s energy landscape.’

By Peter Barker