Transpower issued a warning on Thursday afternoon about possible power cuts yesterday morning, at a time of unseasonal cold for many, because of heavy demand from consumers and generation constraints.
But the cuts did not materialise.
Consumers reduced power use yesterday morning and major industrial electricity users dialled back demand, while generators made as much electricity available as possible.
Wind power is being promoted by the new government. One wind farm has just been built in the South and two more are planned in the same area.
The Kaiwera Downs wind farm was opened late last year and was in full flow yesterday morning.
Other wind farms are also planned near Kaiwera, at Slopedown in Southland, and the Kaihiku wind farm in South Otago.
Wind farms have been built at Mahinerangi and Mt Stuart over the past 20 years.
Mercury Energy executive generation general manager Stew Hamilton said the company responded quickly to make more generation available on Thursday night into yesterday.
"We had everything that we possibly could running at full noise — at this morning’s 8am peak we were generating about 1400MW including 67MW from our South Island wind farms," Mr Hamilton said yesterday.
"The turbines at Kaiwera Downs start generating at wind speeds of 10kmh and reach full capacity at around 40kmh. The sites have a capacity factor of around 40% which means that it generates 40% of its maximum potential throughout the year."
On Thursday night the company’s North Island wind farms were not producing due to calm conditions.
"At the same time the wind farm at Kaiwera Downs was generating near maximum output of 35MW and our Mahinerangi wind farm was also producing near maximum output of 32MW.
"This really highlights the importance of having generating assets in different locations all over New Zealand as we have — often when it’s still in one place it might not be elsewhere."
Manawa Energy and Pioneer Energy are looking to develop the widespread Kaihiku wind farm. It is planned for land about 7km from Clinton and 12km from Balclutha.
It could potentially produce 300MW, enough power for 135,000 homes.
Manawa Energy said while wind farms could drop to no output when it was still and calm, it was more likely they would still offer some reduced contribution.
"Given the geographical size of the Kaihiku wind farm, it would be unusual for it to produce no generation. In addition, it is unlikely to be calm across all wind farms nationally at the same time," the company wind generation team said in a statement yesterday.
"During the high-risk period this [yesterday] morning, Pioneer Energy’s Mt Stuart wind farm was operating between 50% and 100% output, peaking at 6am, and dropping to 50% by mid-morning.
"Given the proximity of Mt Stuart to the Kaihiku wind farm site, it’s a reasonable representation of the potential performance of Kaihiku wind farm. If the Kaihiku wind farm was operational today, it would likely have contributed more than 150MW of generation, significantly de-risking the national position."
Contact Energy declined to give details about the company’s planned Slopedown wind farm. It was hoping to build a large wind farm, set to produce between 250-330MW, enough power for 110,000-150,000 houses.
