Many aspects of turbine performance and load can now be predicted with good accuracy, said Garrad, but can power curves be predicted? The uncertainty of airfoil characteristics in the stall region has long bedevilled accurate predictions of the relationship between power and wind speed.
The differing needs of onshore and offshore wind plant may prompt the emergence of separate design concepts, consultant Andrew Garrad told last month's British Wind Energy Association conference. Onshore constraints on design -- on size, noise, appearance, number of blades and speed -- could disappear or become less important, said Garrad. The high cost of offshore foundations means there is a commercial incentive to build rotors with high power ratings, prompting development of very large machines -- 3 MW-5 MW or more. Machines of this size onshore would be problematic to transport and visually more dominant. Garrad emphasised the need for integrated design, considering the whole turbine rather than an assembly of components. He thought innovations were still arising and said control was an area where more sophistication could improve performance.