Net Zero Grid Pathways Latest Updates

Scenario Development – EDGS 2019 variations consultation

December 2020: Consultation released

Following our two online meetings with an expert industry panel, and subsequent considerations, we are now welcoming feedback feedback on our draft EDGS 2019 variations.

Making a submission

Consultation is open until 5:00pm, Friday 26 February 2021. Submissions should be emailed to using the heading “Draft EDGS 2019 variations consultation”.

Submitters may comment on any relevant aspect of our topic. While we have asked some specific questions in our consultation document, we welcome all relevant input.

Please note that submissions will be posted on our website and be public. If any aspect of your submission is confidential, please advise us and we will not publish that part of the submission.

As described in the document, our draft approach departs from simply varying the five scenarios described in the EDGS. We are not proposing to vary the stories underlying each scenario, but are proposing demand and supply scenarios separately. Some changes that have occurred since the July 2019 EDGS were published, impact electricity demand and some impact electricity supply. While we are proposing five demand scenarios, we are also proposing a matrix of possible supply scenarios. In our view, there is too much uncertainty about future electricity supply options to rely on just five scenarios. We propose leaving the supply possibilities as a matrix, with a suitable set of final scenarios to be determined according to the investigation.

Our thanks to the Transpower Net Zero Grid Pathways Scenario Development Panel members who provided insightful and useful feedback on our initial thoughts in regard to bringing the EDGS 2019 up-to-date.


The Transpower Net Zero Grid Pathways Scenario Development Panel met for the first time on 5 November 2020. This was the first of two meetings to discuss whether the EDGS 2019 should be varied, in order to bring them up-to-date and ensure they are suitable for both phases of our Net Zero Grid Pathways (NZGP) project, including phase one, our Accessing Lower South Island Renewables (ALSIR) project.

Read the Pre-Reading Document (provided to panellists ahead of the 5 November 2020 meeting).

The second online meeting was on 2 December 2020, which saw panellists discuss our application of the variations they recommended on 5 November and the resultant draft EDGS 2019 variations. The purpose of this consultation was to offer other interested parties an opportunity to comment on any modifications we should consider for our EDGS 2019 variations. You can view the second meeting below: 

Read the Pre-Reading Document provided to panellists ahead of the 2 December 2020 meeting). 

Observers to the 5 November online meeting were offered the opportunity to submit questions as the meeting progressed. Those questions were noted and will be treated as written submissions, so do not need to be repeated.


The meeting facilitator, John Hancock, clarified two particular aspects of the pre-reading document for the panellists and observers yesterday. In our own words, these were:

  1. Transpower’s scenario development process reflects a need to be getting on quickly to consider the implications of the Tiwai aluminium smelter closure for electricity transmission. MBIE are looking to update some data in the EDGS soon. They are currently considering which aspects to update, ahead of a full scenario refresh. This work will be coordinated with modelling work that supports development of climate change pathways. Some of MBIE’s updates may be for aspects we are considering variations for now. We can’t presuppose what those updates may be, but our approach will try and ensure the range we reflect in our variables will cover any MBIE changes.
  2. The reference tables in the pre-reading document are included for information. They highlight a difference between EDGS and WiTMH, compared to the BEC scenarios, which is not well explained. The two BEC scenarios are more conventional scenarios than either EDGS or WiTMH. Traditionally, scenarios are different future paths that could emerge and which are used to inform development of company long term strategy. They are plausible, but not necessarily likely and their probability of occurrence cannot be determined. Both EDGS and WiTMH are more like forecasts, or futures, than conventional scenarios. They are different states of the future, but we assign a probability to them in order to analyse the economics of transmission investment options. In that regard, the BEC scenarios may be more extreme than EDGS and that appears to be the case from the tables. The BEC scenarios and EDGS are intended for different purposes, so the differences are not unexpected.


23 October 2020: Scenario Development Panel Confirmed – Meetings Scheduled

Thank you for your interest in our scenario development process.

Applications for the panel closed 16 October 2020 and selected Panel members are below



John Hancock

Meeting facilitator

Paul Botha

Roaring 40’s

Pauline Martin

Genesis Energy

Allan Miller

Allan Miller Consulting

Marcos Pelenur

Energy Efficiency Conservation Authority

Jen Purdie

University of Otago

Glen Sullivan


Ryno Verster


Philip Wong Too

Tilt Renewables

Online Panel Meeting  5 November 2020

  • To discuss whether and how the EDGS 2019 should be varied to bring them up to date for issues that have occurred since their publication in July 2019

Online panel meeting 2 December 2020

  • The purpose of the second panel meeting will be to consider and discuss the draft scenarios themselves.   

Read our industry update announcing the panel.

Transpower seeks applications for Net Zero Grid Pathways Scenario Development Panel

Read our latest industry update 

Scenario Development Terms of Reference [ pdf 171.26 KB ] (PDF)

Apply to join the Scenario Development Panel [ pdf 106.35 KB ](PDF)

Industry Update 28 September

A short summary of the project is here [ pdf 370.53 KB ]

You can access a copy of the presentation here [ pdf 1.14 MB ]

The recorded video is also available to view below.


Waikato and Upper North Island Voltage Management Project

In September 2020, the Commerce Commission approved Transpower’s Major Capital Expenditure Proposal for the Waikato Upper North Island Voltage Management project. In their determination they stated that the closure of the smelter “increases the likelihood of the [Huntly] Rankines’ removal from normal service’, which in turn increases the risk of voltage stability issues in the Waikato and Upper North Island region. Since 2012, over 1000MW of generation has already shut down in Auckland and through the Waikato. This generation reduction coupled with the actual and expected demand growth in the region raises significant voltage stability risks. As we progress the project to manage these risks, we will provide updates via the linked webpage.

Read more about this project here


Net Zero Grid Pathways Phase One Timeline

Sept-Dec 2020

•Confirm potential system development needs from updated studies

Oct 2020

•Industry engagement on possible post smelter demand and generation scenarios

Dec 2020

•Updated list of areas for investigation for investment

•Publish System Security Forecast - access here

Early 2021

•Finalise demand and generation scenarios with industry and MBIE

•Commence work on individual investment cases for Commerce Commission approval

End 2021 – End 2022

•Submission of investment cases to Commerce Commission

Early 2022 – Mid 2023

•Indicative timeline for Commerce Commission Approval of investment cases


•Delivery of approved investments