Last updated: 09 May 2025
Short-list consultation now open
Transpower is seeking views on a proposed investment of up to $1.4 billion in Aotearoa New Zealand’s Cook Strait electricity link to ensure it can deliver an affordable and reliable electricity supply to the country as the economy electrifies over the next 40 years.
We're inviting feedback on the replacing the ageing electricity cables that cross the Cook Strait, our proposal to increase the cables' capacity and upgrades to the control system, cable termination station and other parts of the HVDC link.
Consultation is open from 7 May - 20 June 2025. Email your feedback to [email protected].
Short-list consultation documents
Read a summary of the HVDC link upgrade programme consultation here
- HVDC Link Upgrade Programme - Short-list Consultation Overview
- HVDC Attachment 1 - Need for investment, demand and generation scenarios
- HVDC Attachment 2 - Cable Condition Assessment Report
- HVDC Attachment 3 - Short-list of investment options
- HVDC Attachment 4 - Benefits modelling
- HVDC Attachment 5 - Investment Test
- HVDC Attachment 6 - Indicative Pricing Allocations
- HVDC Attachment 1 Addendum - Appendix B - Demand figure data
Short-list consultation webinar
Transpower will host a webinar on the short-list consultation at 2.30pm on Wednesday 21 May. Click here to join on the day. If you have questions you'd like us to answer in the webinar please email them to [email protected].
What are we doing?
Transpower proposes to replace the ageing electricity cables that cross the Cook Strait at the end of the decade. When we replace the cables, there’s also a strong case for installing an additional cable. This will transfer more electricity as well as providing more back-up in the case of an unplanned outage. It will set New Zealand up for an affordable and resilient electricity supply for the long term.
Other parts of the link requiring upgrades in the early-to-mid-2030s include the cable termination stations that connect the undersea and overland parts of the HVDC link and the control system that manages power transfer. Transpower is proposing to deliver these at the same time as the cable replacement as a suite of HVDC link upgrades to be completed in 2030 and 2031.
In December 2024 we secured global cable solutions supplier Prysmian to replace the submarine electricity cables. The agreement reserves the cable manufacturing, the ship, and the experts to install the cable and ensures the project will go ahead.
Why are we doing it?
New Zealand’s High Voltage Direct Current (HVDC) link between the North and South Islands is a critical part of our national infrastructure. It helps ensure power is available where and when it’s needed by connecting communities and businesses to electricity generators across Aotearoa.
The existing undersea electricity cables were installed in 1991 and will reach the end of their expected life in the early 2030s, meaning they must be replaced. Due to international supply constraints for submarine cables, Transpower has in 2024 secured a cable supplier to replace the cables. Transpower’s 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.
Other parts of the link requiring upgrades in the early-to-mid-2030s include the cable termination stations that connect the undersea and overland parts of the HVDC link and the control system that manages power transfer. Transpower is proposing to deliver these at the same time as the cable replacement as a suite of HVDC link upgrades to be completed in 2030 and 2031.
Planning and delivering the projects together will minimise the impact on the electricity system while the work is done, deliver cost efficiencies for New Zealand, and help Transpower confirm contracts with the suppliers of undersea cables and other HVDC equipment.
Timeline and updates
- August 2024 - Published an information and consultation paper.
- October/November 2024 - Transpower completed a high-level evaluation of costs and benefits and decided to enter contract negotiations with the option of installing replacement cables with a 1400 MW capacity.
- December 2024 - Transpower entered a formal Capacity and Reservation agreement with a supplier. A deposit to the supplier is required to secure the manufacturing and installation slot.
- First half of 2025 - Begin engagement on site works e.g. cultural/environmental inputs. This is expected to span several months.
- May 2025 - Short-list consultation on our preferred option
- Second half of 2025 - Submit major capex proposal to the Commerce Commission.
- 2026 - Commerce Commission decision on recovery of expenditure.
- 2026 - Enter into a full contract with the cable supplier.
- Mid to late 2029 - Cable manufacture begins (indicative next manufacturing slot available).
- Early 2030s - Install/commission new cables.
More information
December 2024 agreement for cables, ship and installation
- Transpower secures cables, ship and installation for Cook Strait project (13 December 2024)
August 2024 Information and Consultation paper about upgrading and enhancing the capacity of the submarine cables.
- See the consultation paper and submissions (August - September 2024)
March 2024 discussion paper exploring future role of HVDC electricity link