Transpower seeks Cook Strait cable replacement feedback

Transpower wants feedback by August 23 on plans to replace ageing electricity cables across Cook Strait, including whether capacity should increase.

Increasing cable capacity from the existing 1200MW to 1400MW would provide good value for New Zealand and future-proof this part of the electricity system, says Transpower grid development acting executive general manager Cobus Nel.

“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,” he says.

“Based on the increased benefits of a 1400MW transfer between the islands shown in our analysis, we believe we should also take this opportunity to increase the cables’ capacity.”

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 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, says Transpower.

Electricity will continue to transfer southwards at times of surplus North Island generation, and enhanced capacity would give the overall electricity system additional resilience, it says.

Nel says Transpower has begun work to establish 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,” he says.

“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 where registrations are also being taken for a webinar on the paper on Friday August 9, 2pm.

Email Cook Strait cable feedback to grid.investments@transpower.co.nz by Friday August 23.