Shanhaiguan builds wind turbine ship

Faced with dwindling world fossil fuel reserves, energy companies are exploiting alternative sources at an increasing pace. The latest development in the wind-mill energy farm concept is the construction of offshore facilities. And UK-based engineering firm, Mayflower Energy Ltd, has come up with a practical solution to the problems associated with the installation of wind turbines in coastal waters. A unique high technology wind turbine installation vessel (TIV) has been designed to meet the shortcomings of current installation practices and techniques. Such inadequacies include limited operational weather windows, poor capacity and the high levels of infield logistical support vessels required. The 130.5m long vessel has a beam of 38m and a depth of 8m. It has been developed specifically for the installation of multi megawatt offshore wind turbines, foundations and ancillary services. Mayflower has placed its first order for one of these TIVs with an option for a second vessel from China?s Shanhaiguan yard. The UK?s Graig Shipping will supply a full supervision support package for building the first unit. China secured the order on the basis of competitive pricing and because its shipbuilders are flexible and willing to adapt to new technology and new designs, says Graig. The company advised Mayflower on choice of yards, introduced Denmark?s Knud E Hansen as the designer, DNV as a suitable class society and assisted in yard negotiations. Its China-based supervision team will now oversee the building and delivery of the first vessel, which is due to enter service in February 2003. Mayflower?s TIV design is such that it can operate without the need for support vessels, is self propelled and highly manoeuvrable. The TIV utilises a state-of-the-art dynamic positioning system to accurately hold the vessel on location while the jacking system raises it to the operational elevation providing a safe and stable working platform. The high capacity, high speed system means operations are possible beyond the traditional weather windows. The TIV?s jacking system gives it a water depth capability ranging from under 3m (carrying a single turbine) to over 35m. The design has taken into account the varying conditions throughout European waters from the Baltic Sea to the Northern coastline of Scotland. It has a jacked survival capability of a 100 year storm (force 12 Beaufort scale) and can withstand a 50 year wave of 14m. The vessel has a large operational cargo capacity capable of carrying 10 complete 3.5MW wind turbines with an installation rate of one complete turbine a day in North Sea conditions. High performance, main and auxiliary cranes, 300 and 50t respectively, ensure efficient lifting operations while the six jack-up legs have an individual jacking capacity of 2,500t and a holding capacity of 3,000t. The cargo deck area measures some 1,750m2 and has a 10,000t load capacity. The vessel will house a full engineering crew of up to 50 persons. The vessel will be powered by four main gensets with a total output of 9,120 kVA, while a further power supply of 650 kVA is provided by a pair of auxiliary gensets together with an emergency 250 kVA unit. A transit speed of 10.5 knots is achieved by means of four 1.5MW azimuth thrusters and manoeuvrability is enhanced by the installation of three 670kW tunnel bow thrusters. “The UK government has plans which will require the installation of 1,300 new 2MW offshore turbines over the next 10 years,” says David Donnelly, chairman of Mayflower Energy. “There are also plans for major installations around other European coasts.”