Last updated: 17 Mar 2025
What are we doing?
We need to continually operate, maintain and develop New Zealand's transmission network – the National Grid – to ensure we meet the ongoing electricity needs of New Zealanders.
This project is about increasing the capacity of the 220 kV grid between Bunnythorpe and Whakamaru in a staged manner to meet the requirements of increasing generation and demand. Similar projects are underway with respect to the capacity of the HVDC and further investment in the Wairakei Ring (subsequent to the Atiamuri series reactor project underway). The first project underway is to increase the operating temperature of the sections of our two lines that connect between Tokaanu and Whakamaru (known as a thermal upgrade), followed by replacement of the conductor (wire) to provide greater capacity. Following this work, (around 2026) Transpower will undertake another thermal upgrade on the southern portion of these lines between Bunnythorpe and Tokaanu
Why are we doing it?
As part of our Net Zero Grid Pathways work, we have identified that with the expected electrification (ie electric vehicles and industrial processes) and expected new generation in the North Island there is significant economic benefit to New Zealand in relieving potential constraints in our core network. More information on the Net Zero Grid Pathways Project can be found here.
More Information
Because of the relationships between this project, the capacity of the HVDC and the capacity of the Wairakei Ring, we are undertaking the investigations concurrently. A long-listing document outlining the need and long list of options for each project was released and consulted on towards the end of 2021, and at the end of 2022 a Major Capex Proposal was submitted to the Commerce Commission