Transpower issues supply reassurance

• Published date: 24 June 2022

Contact Energy’s 105 megawatt peaker at Stratford failed to start, one of Genesis Energy’s units at Huntly had to temporarily reduce output by 150 megawatts, and wind generation dropped from a forecast 90 megawatts to 30 megawatts

Transpower worked with lines companies to remove some demand from the electricity system.

It briefly switched off electricity used by some hot water cylinders — a move it said it makes regularly during winter, which doesn’t impact people.

Transpower spokesman Nathan Green told the Herald 440 megawatts of residual electricity generation were expected to be available by yesterday evening — a buffer sufficient to ensure supply meets demand.

Furthermore, he said temperatures are forecast to rise a little and demand for electricity was likely to fall over the long weekend.

Transpower chief executive Alison Andrew assured that lines companies knew what was expected of them yesterday, and “they moved quickly to manage controllable load and reduce demand to get us through the emergency”.

“No one was disconnected, and the system stayed stable throughout,” Andrew said.

Contact Energy chief generation officer John Clark said a mechanical fault meant the company’s fast-start gas peaker couldn’t be switched on. The cause of the fault is still being investigated.

Clark said that all of Contact Energy’s available generation was supplying the electricity grid yesterday morning.

He said Transpower did its job, asking for extra supply and reduced demand.

“The system responded with additional electricity made available by generators, and demand from electricity consumers reducing,” Clark said.

Genesis Energy said an electrical fault on a fan reduced output from one of its units at Huntly from 240 megawatts to 108 megawatts.

“Unit 4 is back up and running and available to 220 megawatts and we anticipate the unit to be fully available...