Power crisis: Jacinda Ardern says outage 'not good enough', calls for answers

The Government is demanding answers from officials and electricity generators about what caused some New Zealanders to have their power cut on one of the coldest nights of the year, something Jacinda Ardern says is "not good enough".

An insufficient amount of generation to meet record-high demand on Monday night meant thousands of Kiwis in some parts of the North Island had their power switched off as many attempted to heat their cold homes. While demand on chilly winter nights normally sits between 6500MW and 6700MW, it hit north of 7100MW in the evening.

Jacinda Ardern said on Tuesday there are questions to be answered about what happened. 

"We cannot, hand on heart, say right now that all of the generation that could have come online did come online. That is a critical question. There may still be a case that this could have been prevented," she told reporters.

"We need to know as quickly as possible whether that was the case because it means we can target our solution. What happened wasn't good enough, even if it really was a peak on an extremely cold night, it is still not good enough that we weren't able to warm our homes."

Energy Minister Megan Woods on Tuesday morning met with Transpower - the state-owned enterprise responsible for the country's electricity transmission - and the Electricity Regulatory Authority, and asked officials to stand up a coordinating team. 

She wants to know why the HVDC cable - the 'Cook Strait cable' connecting the North and South Islands' electricity networks - was running at just 50 percent capacity and why the third Rankine at the Huntly Power Station wasn't fired up. Some generation was also not available due to still wind conditions, the minister said. 

"There was a forecast that there was going to be more wind generation but it was stiller than was expected. That is not unexpected. When it is cold and frosty, often there isn't wind.

"We lost 100MW of capacity out of Tokaanu hydro system in the central North Island. My understanding is that was associated with the storm stirring up some weeds that stopped the ability for that system to generate."

Woods has now written electricity generators to ensure no maintenance issues cause problems, for "reassurance that they are operating at generation capacity, and seeking assurance what might happen tonight". 

In her letter to generators, Woods said consumers "do not expect our electricity market to fail under demand pressures at any time, not least on a cold winter evening".

She wants to know all actions each company took in response to a request for more generation on Monday and that they will participate with information requests from Transpower and the ERA. The minister also wants generators to say if they have issues with generation that may impact their ability "to operate at peak times and maintain security of supply".

"The system has let New Zealanders down in this instance. I am seeking advice to ensure this does not happen again."

Wood said the 2018 ban on new oil and gas exploration had no impact as any new permits that would have been issued since would still be in the exploration stage. She also noted no new gas had been found in New Zealand's waters since 2000.

Many Kiwis were on Monday night furious about not receiving warning their power was about to go out. While Transpower did send out a series of alerts to the market on Monday morning and afternoon about low generation, the first many families heard of it was from distribution companies in the evening.

Wood said that process is something that would be looked into.

"One of the things that I have asked MBIE in terms of their coordination role is to get some clarity on who and how we should be communicating with consumers," she said.

"That is certainly one of the questions that I have, is the notice that people were given and people not having the opportunity to prepare adequately for that."

Transpower operations general manager Stephen Jay told The AM Show on Tuesday morning that it works hard to send the right communication out, but it is a formal process. 

"We communicate very formally to the market participants, the generators, the distribution businesses, the direct connected generation and the direct connected industries," Jay said.

"They have channels of communication down through the retailers to the consumers. We will have to work with the industry to make sure that chain of communication works but it is very formalised, from the national control centres out there in terms of what is going on."

Speaking before 7am on Tuesday, Jay couldn't say what caused the insufficient generation.

"We will need to look into why there wasn't enough generation available last night. There is normally some underlying reason in terms of why there is insufficiency out there. That is part of our ongoing investigation to look into that."