PNCC'S consultation document was misleading.
Fire caused by friction, electrical fault or lightning strike is an ever present danger. These fires are fuelled by the composite fibreglass materials used in the nacelles and blades and at 125 metres high are virtually impossible to put out. Do you want to risk the Turitea Reserve, Hardings Park, private pine plantations and our water supply in this way ???
Watch a turbine implode. This turbine was one of two in Denmark which collapsed earlier this year. The debris was thrown over a 1/2 mile radius. See a video clip of the debris here.
NB this turbine is 61 metres ( 200 feet ) high, the Turitea turbines are 125 metres high.
Why do wind turbines fail ?
So what's the risk of turbine failure? Mike Graham, professor of aerodynamics at Imperial College, says a modern turbine typically spins at 25rpm, which translates to a few million times a year. "Turbines have to face a lot of force," Graham says. "They are equivalent to the lift forces faced by aircraft in takeoff, and some blades are of comparable size now to the wing of a Boeing 747."Unlike aircraft, however, wind turbines operate in "the lower part of the Earth's atmosphere, where it is very turbulent and wind is more interrupted. Repetitive loading of forces causes cracks. But the industry is well aware of this." Engineers calculate the forces and add a safety margin, which is then built into the design.
But crucially, manufacturers do not disclose how close to tolerance they make their products, according to Professor Leon Freris, a consultant who is also a member of the board of Ascot Renewco, an insurance company which underwrites policies for turbines. "The most critical components on a wind turbine in terms of fatigue loading are the blades and the gearbox," Freris says. "The majority of blades at present are made of glass-reinforced plastic." They are made to last 20 years, but accelerated fatigue tests, and two years of testing, are standard before new designs are included in products.
Errors can be made, though. Earlier this year, Suzlon Energy had to repair or replace almost its entire stock of 1,251 turbine blades, after many developed cracks. The refit is reckoned to have cost the company $25m (£14m).
Graham says most wind turbines require gearboxes to enable the slowly turning blades to power fast-running generators: "It's one of the major problem areas. Gearboxes are big heavy things based at the top of a tower and they are prone to failure. There is a lot of unsteady loading because they operate in wind."
http://www.windaction.org/news/17801
NB: the 110 m high Tararua 3 turbines have been failing regularly after only 1 year in operation. Blades are delaminating ( one actually fell off last year ) and gearboxes failing. Drive shafts have had to be supplied with undersized bearings. The supply line for these turbine parts stretches clear to the other side of the world.
In the Environment Court recently Palmerston North was referred to as "Propeller City "in response to proposals to swamp the heritage landscape immediately behind the city with monster turbines.
We have a wind farm zone and the prospect of a further 250 or so turbines south of the Pahiatua track is unacceptable. The Vestas turbines at Tararua 3 are falling apart after less than a year in operation. Repair crews are there every day dealing with gearbox and bearing failures and delaminating blades. A 45 metre blade last year simply fell off. The wind is too turbulent, too unpredictable.
An important point.
During the winter months ( 2008 ), due to weather systems with light to no wind at all, Manawatu wind energy has made only a neglible and intermittent contribution to compensate for low levels in the Southern hydro lakes.
Wednesday, 11 Jun 2008
Wind farms don't ease power peak
http://www.stuff.co.nz/stuff/dailynews/4579551a6554.html
Taranaki's first wind farm, planned to be built on the coast at Waverley, will probably contribute nothing to meeting the country's peak winter power demand.National electricity grid operator Transpower has revealed that turbines on the three Manawatu farms have been generating at less than 1% of their capacity during winter evening peaks for the past three years.
Click on the comment below for the full story on wind farm inefficiency.
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