The machine, standing 70 metres tall, is being tested in Orkney's rigorous wind conditions which are similar to those offshore. It was erected at Burgar Hill over a period of two weeks in May, but the machine was unveiled to the wind industry one month later in June at Wind Energy 2002 in Hamburg. The 45 metre blades are from LM Glasfiber. Although the project was managed by NEG Micon Rotors from its blade factory on the Isle of Wight off southern England, the firm's Patrick Geraets says it is not yet able to manufacture blades of the length required. But, he adds, the hub was designed by NEG Micon Rotors.
Both the 80 metre and 92 metre rotor versions of the turbine use pitch regulated variable speed technology (PRVS). Ole Gunneskov of NEG Micon explains that until now the company has used stall regulation in all its machines. "But now is the right time to supplement these with the use of PRVS as this allows increased regulation possibilities," he says. "The size of the new turbine also makes it important to bring down the dead weight of the rotor through reduction of the dead weight of the blades and advanced regulation." He adds that the company is introducing PRVS now because it is cost effective for that type of turbine and any teething troubles with the technology have all been solved.
An "add-on" crane, which can be shared between all turbines in an offshore wind farm, means that they can be serviced without the need to order a floating crane. The turbine can be assembled on dry land and tested on a base before being transported and installed offshore. Gunneskov admits that carrying out "lift-in-one installation" requires large and complex equipment. "But there is rapid development in this kind of equipment," he says. "It is a method that saves time, and this puts us at the leading edge of developments."
The new Orkney turbine is physically the largest ever installed in the UK -- bigger even than the 3 MW experimental turbine at Burgar Hill which was demolished in November 2000. The project is costing £1.5 million and the turbine will generate up to 12 GWh a year.