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Getting the Wind Up

An outlandish-looking structure on farmland 100 miles south of Auckland represents a bid to revolutionise windpower and the energy industry, not just in New Zealand but also overseas.

The prototype Vortec 7 wind energy turbine started operations recently, using a unique design that has been waiting at least 20 years to be developed.

The turbine is the world's first commercial diffuser augmented wind turbine (DAWT), which uses an aerodynamic device to create a suction effect downstream of the turbine to double the windspeed at the rotor and so boost efficiency and output.

Initial results are very promising, and developer Vortec Energy Ltd says that interest overseas has already been strong.

The Netherlands government is said to have put their new turbine purchases on hold until the results of the Vortec 7's performance are evaluated.

The DAWT technology was developed by US company Grumman Aerospace in the 1970s as part of a US Energy Department-funded project. Eight years of wind tunnel testing puts the technology well beyond the experimental stage, but its full potential was not realised because of problems in securing appropriate construction material and a redirection of R&D focus.

Vortec Energy has used high-tensile ferrocement in the production of the seven-storey, one-third-scale prototype, finding this a lighter, stronger material than the steel conventionally used in turbine support structures. New developments in steel over the past couple of years, particularly in the protective coatings needed in the harsh coastal environments common to many wind farms, means that steel does remain an option for future construction. "The key to the economic success of the Vortec lies in its ability to generate up to eight times the energy generated by a conventional wind turbine without increasing the production cost eight times," says Vortec's managing director Robin Johannink.

Johannink was pleased that the early results from the machine showed the match between wind speed and generator output within 1% of predictions, auguring well for the trial. Fifteen different wind speeds were tested and the Vortec 7 was found fundamentally to mimic wind tunnel results, a result which Johannink says they didn't find surprising although others may have.

"Most traditional wind power people are of the view it won't work," he says, adding that many have based those impressions on the early work done through the 1920s-50s on diffuser design.

Despite the questions and scepticism, hopes for the new machine remain high, with Vortec predicting that the full-scale machines will produce electricity at about 4 cents/kWhr, or about half that of conventional windfarm technology.

"If Vortec 7 performs to expectation, windpower is set to become the environmentally friendly energy source that is at last competitive with all other forms of power generation. It may well produce the cheapest cost of energy for any new New Zealand generation, and in the world context will be even more competitive," says Johannink.

The prototype has gained a great deal of interest, as well as a half-million-dollar evaluation grant from the Foundation for Research, Science and Technology. Its performance will be evaluated by researchers from the University of Auckland and from the Crown Research Institute Industrial Research Ltd.

Johannink says that the company aims to build two Vortec 20s, so named for the blade diameter of 20 metres. They have strong interest in a site in South Australia and Johannink would like to see a Vortec 20 operating in New Zealand. What happens from here is purely a matter of commercial negotiation, he says.