Transpower Seeks Feedback Ahead Of Cook Strait Cable Replacement

Transpower plans to replace the ageing electricity cables that cross Cook Strait at the end of the decade and is today asking the electricity sector and other stakeholders if they agree New Zealand should take this chance to also increase the cables’ capacity.

Cobus Nel, Acting Executive General Manager Grid Development, said Transpower’s provisional analysis shows that increasing the capacity of the cables from the existing 1200 MW to 1400 MW would provide good value for New Zealand and future-proof this part of the electricity system.

“We need to replace the cables by the early 2030s and, as submarine electricity cables are in high demand internationally, we need to reserve our place in the manufacturing queue soon. Based on the increased benefits of a 1400 MW transfer between the islands shown in our analysis, we believe we should also take this opportunity to increase the cables’ capacity.

“We want to understand whether the electricity sector and other stakeholders share our view,” Mr Nel said.

The submarine cables form part of the High Voltage Direct Current (HVDC) link that moves large amounts of electricity between Benmore substation in the South Island and Haywards substation in the North Island.

Transpower expects that, in the future, wind and solar power will replace much of the gas and coal-generated electricity in the North Island. At times when wind or sunshine hours are low in the North Island, the HVDC link will play a larger role in keeping electricity supply stable by transferring South Island-generated electricity northwards. It will also continue to transfer electricity southwards at times of surplus North Island generation, and enhanced capacity would give the overall electricity system additional resilience.

Mr Nel said Transpower has begun work to establish the options for replacing and/or increasing the capacity of the cables and expects to have reliable information on potential solutions and cost estimates in the last quarter of 2024.

“As we need to reserve a booking for cable manufacturing soon, we are particularly interested in hearing views from stakeholders to assist us in determining whether increasing the HVDC capacity is good value.

“Helpful information could include planned electricity generation that we’re not already aware of, plans for additional bulk electricity storage in the North Island, or significant electricity load increases through industrial electrification.

“We have an opportunity now to make a decision that will establish New Zealand’s electricity pathway for the next 40 years, which is the life of these cables. We look forward to hearing others’ views.”

The HVDC Cable Replacement and Enhancement Information and Consultation paper is on the Transpower website. A webinar on the paper will be held on Friday 9 August at 2pm and you can register via the Transpower website.

Feedback is open until Friday 23 August and should be emailed to grid.investments@transpower.co.nz.

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