New Zealand’s grid operator Transpower wants to replace the ageing power cables underneath the Cook Strait that carry electricity between the North and South islands in an investment worth up to $1.4 billion.
The 350 kV high voltage direct current link stretches from Benmore Substation in Canterbury’s Waitaki Valley to Haywards Substation near Lower Hutt.
They were predominantly overhead lines but include three submarine cables across the Cook Strait.
Transpower chief executive James Kilty said the cables were “really important assets” for the country.
“They’re coming to the end of their 40-year life and our proposal is to replace them and extend them for another 40 years.”
Kilty said Transpower was proposing to install a fourth cable.
“Looking to the future as New Zealand electrifies, we are proposing to install in this programme a fourth cable, just to allow a bit more electricity to flow between the islands.”
He said this would be a “prudent and cost-effective investment” to future proof the country’s electricity supply.
“We only get one shot at this every 40 years and we’re keen to hear from stakeholders before we proceed.”
The original cables were installed in 1965 and then replaced in 1991.
Condition assessment of the currently installed cables confirmed that end-of-life replacement was due in 2032.
Other parts of the link requiring upgrades round this period include the cable termination stations connecting the undersea and overland parts of the link, as well as the control station which manages power transfer.
Infrastructure NZ chief executive Nick Leggett said the Commerce Commission would examine the Transpower proposal.
“They’ll evaluate it to make sure they’re not spending too much and charging customers too much, but equally, that the work is being done at the right time.”
The Commerce Commission would also decide whether or not costs of the programme could be recovered through Transpower transmission charges to be spread over the expected 40-year lifespan of the assets.
Feedback on the HVDC proposal was due by June 20.
