Wind turbine design could potentially generate 20 megawatts

www.onlinetes.com
7/30/2010

A sycamore seed design may soon be revolutionising the wind power industry. British engineers are designing a giant wind turbine that would rotate on its axis and measure nearly 900ft from up to tip, generating up to 10MW of power.

Engineering firm Wind Power Limited is developing the Aerogenerator, along with architects at Grimshaw, academics at Cranfield University and Rolls Royce, Arup, BP, and Shell. According to those behind the design, the turbines could generate 20MW or more of power. Engineers are now looking at ways of adapting the design to make them more efficient because of the extreme weight gained after scaling up the diameter of the turbine.

The Aerogenerator has two arms coming out of its base to form a V-shape, with rigid "sails" mounted along their length. The arms act like aerofoils as the wind passes over, helping to generate lift. The first Aerogenerator could be up and running by 2013. Other firms are also trying to create a new type of wind turbine that generates up to 10MW of power. Clipper Windpower, another wind power firm, has already announced plans to build the giant Britannia wind turbines that could rise 600 feet above the North Sea.

Feargal Brennan, head of offshore engineering at Cranfield University, explains: "Upsising 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. 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".

Offshore power is seen as a more acceptable option for renewable energy than land-based turbines. Theo Bird of Wind Power Limited says: "Offshore is the ideal place for wind power but is also an extremely tough environment. The US wind researchers who worked on vertical axis projects have always regarded the technology as great to work with at sea because it can be big, tough and easily managed".