ºÃÉ«ÏÈÉúTV

A new design of offshore wind turbine that doesn’t have the constraints of more traditional designs has been unveiled by British company Wind Power.

With a blade span of 270m the Aerogenerator X generates twice the power but is half the weight of the firm’s original Aerogenerator design and is claimed to be one of the only real alternative solutions available to help deliver the UK’s offshore wind strategy.

The Aerogenerator X, which has a generating capacity of 10MW, does not have the same weight constraints as a normal wind turbine and the blades do not suffer weight-induced fatigue, it’s claimed. The design, which is the result of a 18-month feasibility study, is half the height of an equivalent horizontal-axis turbine and its weight is concentrated at the base of the structure.

Upsizing conventional onshore wind turbine technology to overcome cost barriers has significant challenges, not least the weight of the blades, which experience a fully reversed fatigue cycle on each rotation. As the blades turn, their weight always pulls downwards, putting a changing stress on the structure, in a cycle that repeats with every rotation - up to 20 times a minute.

Professor Feargal Brennan, head of offshore, process and energy engineering at Cranfield University, said: ’In order to reduce the fatigue stress, the blade sections and thicknesses are increased which further increases the blade self-weight. These issues continue throughout the device. Drive-train mountings must be stiff enough to support the heavier components inside the nacelle on top of the tower, otherwise the systems can become misaligned and the support structure is also exposed to extremely large dynamic thrust and bending stresses, which are amplified significantly with any increase in water depth.’

The Aerogenerator X is the conclusion of a feasibility study called the NOVA project undertaken by Cranfield University, QinetiQ, Strathclyde University, Sheffield University and Wind Power Limited supported by consultant engineers and project managers, incluing Arup and architect Grimshaw.

Speaking at the unveiling of Aerogenerator X John Roberts, head of energy at Arup, said: ’Despite the installation of a number of large wind turbines offshore, the problems of increasing capital cost for deeper water remains unsolved as does the issue of safe operability in the marine environment. There is a tremendous opportunity for new ideas to make a difference to the commercial viability and operability of offshore wind power. More cost-effective solutions will be essential if offshore wind power is to make the ’hoped for’ contribution to the UK’s green house gas emission reduction targets.’

Wind Power Limited is now in the process of entering a memorandum of understanding with Arup to help continue project development. It is hoped the first turbines will be built in 2013-14.