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New Zealand

Field testing of scale model to start -- Vortec still in design

Wind tunnel testing continues to be a strong focus of the research side of operations at Vortec Energy, the New Zealand company behind an unusual diffuser-augmented wind turbine design which has been under development for the past five years. The aim of the testing program is to quantify diffuser power as accurately as possible. The design has been criticised by the established wind industry as being unworkable (Windpower Monthly, June 1997).

The computational fluid dynamics approach has proved promising, according to Vortec aerodynamics engineer Derek Phillips and project manager Emily Rudkin, and the company is in the process of constructing a field size machine with a two metre blade diameter to look at scaling effects. Rudkin expects this V2 to be ready for field tests this month, following a series of controlled environment trials. The aim is to model the proposed V37, a 37.3 metre full scale design.

The V37 is to have a 1 MW rated drive train and Vortec expects to have its first commercial machine up within the next year. The company is assessing five sites in Europe and Australia. Rudkin says there is a 3.5 MW version planned. Vortec claims that it gets a three times augmentation of wind through the diffuser and expects further improvements through the on-going R&D phase. The company has established some strategic relationships with key component suppliers in Europe and expects that using proven component combinations will help in achieving its goal of a target cost of energy 20% lower than current conventional technology.

Subterranean

One new application, news of which startled participants at the New Zealand wind energy conference in late May, was the suggestion that the Vortec design has sub-sea applications for use under water in canals, rivers and seas. Rudkin saw this as offering a number of advantages over land-based wind options.

"Firstly, the energy density of flowing water is greater than that of the wind, so a smaller sub-sea turbine is required to generate the same amount of power as a wind turbine. Secondly, the resource is guaranteed and is calculable years in advance, an advantage that few other energy resources can offer. Thirdly, the sub-sea environment does not suffer the fluctuations in conditions that are present in the atmosphere and the turbines will not need to be designed to accommodate high turbulence intensities and extreme flow velocities. Fourthly, there are limited aesthetic and environmental impacts, so fewer public objections to the installation of sub-sea farms are likely."

This rather rosy view of the concept presented at the conference by Rudkin and Phillips, did not stop some consideration of the difficulties involved, including corrosion, cavitation, debris control and tethering issues.

"We haven't actually designed the structure," added Rudkin, although she had undertaken her Masters work in testing the under water application possibilities of the Vortec design. A more conventional offshore application above sea level is also seen as likely in the future. Vortec has plans for its initial offshore machine to be 5 MW with a 66 metre blade.

Rudkin noted that conventional wind rather than water power applications is likely to remain Vortec's focus for the foreseeable future. A Vortec licensing arrangement has already been signed with Australian firm Primergy, and other licenses negotiations are under way covering Europe, the United States and Asia, says the company.

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