8 October, 2004
Windflow turbine receives go-ahead from District Council
Windflow Technology has received provisional confirmation from the Banks Peninsula District Council that the company’s
wind turbine at Gebbies Pass (near Christchurch) is operating within the sound level of its Resource Consent. The
turbine will now resume 24-hour operation.
Measurements taken over a two week period recently show that the machine has been below its allowable level. However the
majority of measurements were dominated by higher ambient levels.
Late last year, the company suspended the unit’s operation when the sound level exceeded its allowable level by 1 dBA,
to which a further 5 dBA was added because of a strong tone coming through from a gearmesh frequency. The wind turbine,
with a modified gearbox was reinstalled early in July, and calculations based on the Company’s sound emission readings
near the machine showed that it was operating satisfactorily, with no tonal component and measured levels reduced by a
remarkable 7 dBA.
“The exciting thing is that we now have one of the world’s quietest wind turbines,” said Windflow Chief Executive
Officer Geoff Henderson. “We can now focus on the exciting developments we have been planning for the next few years and
talk about some of the unique positive attributes of our design, to which can now be added ‘very quiet gearbox’!”
While calculations based on the ‘near-field’ sound measurements showed compliance, the Company and the Council wanted to
measure the actual level in McQueens Valley. A meeting of residents in July asked the Council to approve 24 hour
operation for two weeks to allow sound monitoring.
“The problem the Council has had is that on only two days have other sounds been low enough to be anywhere near the
predicted sound level in the Valley,” said Mr Henderson.
“The measured sound levels then were below 30 dBA while the windmill was running which shows we are compliant. On other
occasions either the windmill wasn’t running or wind speeds were high enough to generate ambient sound levels well above
30 dBA. This is consistent with our predictions that there would be few occasions when ambient levels would be low
enough for the turbine sound levels to be measurable.”
Further sound monitoring will take place to obtained refined measurements of the wind turbine’s sound level.