Our water supply is at serious risk.
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."
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
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.