Tuesday 18th May 2010
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Windflow Technology’s half megawatt Windflow 500 turbine has gained crucial design approval from the independent British certifying body Lloyds Register.
The Christchurch-based, two-bladed turbine manufacturer gained the Lloyds stamp of approval under the International Electrotechnical Commission Type certification process for the entire nacelle and rotor assembly of the Windflow 500, it said in a statement. Now only the tower design approval, which is expected soon, will complete Type Certification. The Class 1A Edition 3 certification includes surviving wind speeds over 250 km/h.
Windflow has installed 65 of the turbines at NZ Windfarm’s Te Rere Hau site near Palmerston North in the past three years; and been in dispute with the windfarm operator over the Windflow 500’s performance. These issues have now been satisfactorily resolved from both parties point of view.
“The compact nacelle assembly built around the torque limited gearbox and synchronous generator is the heart of the turbine,” said Windflow chief executive Geoff Henderson. “Together with the two-bladed rotor with New Zealand grown wood-epoxy blades, it is the key to the Windflow 500’s robustness and cost-effectiveness.”
Windflow provided 273 separate documents of specifications and drawings to Lloyds just under a year ago, including some that had over 2000 pages of technical calculations.
The certification will encourage windfarm-development prospects at proposed Long Gully sites near Wellington, Mt Cass in North Canterbury and other potential locations in the UK and Chile Henderson said. There are few half megawatt turbines available around the world, in an industry where bigger is not necessarily better he said.
Turbine output obeys the square cube law, where doubling the rotor size potentially quadruples energy production. But it also means that the turbine is inherently eight times as heavy, which produces limits to economic viability for construction and installation.
“The optimum point is the $64 question,” Henderson said. “The answer is it depends, and varies around the world.”
For example, optimum turbine output in the US seems to be about one to one and a half megawatts, in Europe a two to three megawatt turbine is preferred, while offshore turbines, requiring large ships and really big cranes to install can be even bigger.
Exposed, ridge top sites are better for the smaller, smarter turbine Henderson said. This requires a lighter grade of roading to install, and is a better economic fit given the price received for wind energy.
The Lloyds certification “validates the heart of the turbine,” he said. “It has taken us several years and thousands of hours of engineering brainpower. We have many dedicated young engineers in our team and their efforts are a great contribution to the knowledge economy of New Zealand.”
Windflow’s infrequently traded shares, which in mid-2008 were at $4.25, were last at 98 cents, up from 90 cents in late March.
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