Polar blast - will the electricity system cope?

Tuesday, 4 October 2022

An influx of cold air is set to send temperatures plummeting across Aotearoa New Zealand for the rest of the week. (This video was first published on October 4, 2022.)

Electricity system operator Transpower says generators are offering enough power to see the country through the cold snap that is expected to work its way up the country from Tuesday evening.

But operations manager Stephen Jay said it was monitoring the situation given that those offers could change.

The coming polar blast could see snow fall in the lower North Island, with Niwa forecasting some chance of snow in downtown Wellington on Thursday morning.

Jay said such cold weather was unusual in October and Transpower was forecasting electricity demand on Thursday and Friday could peak within the top 1% of historical ranges for this time of year.

* Power cut risk probably gone for this year, but what about next year?

Transpower said the buffer of supply over demand was smaller than it liked during the Tuesday morning peak.

Power supplies were susceptible to changes in wind speeds and Transpower would continue to work closely with the MetService to understand whether generators’ forecasts for wind generation during the polar blast were likely to be accurate, he said.

But electricity demand was expected to be lower than if the country experienced a similar cold snap in winter, because of the longer daylight hours in October, he said.

“If we see residuals drop below the level we like to hold in the system as a buffer, we will issue a notice to industry requesting additional generation.”

There was a smaller buffer of supply over demand during the Tuesday morning peak than Transpower liked to keep, but the buffer was “still at a comfortable level”, Jay said.

Transpower chief executive Alison Andrew said last week that cold weather in the upper North Island had by far the biggest impact on demand.

Andrew said electricity supply could be as tight next winter as it was this winter, when the state-owned enterprise successfully called on power companies to up their generation several times amid minor scares.

But she said Transpower was confident there would be enough generation to see the market through next winter if generators made all their power plants available.