Consultation on EDGS 2019 Variations to develop generation scenarios

We decided to get input from industry members about whether and how the EDGS 2019 should be further developed to bring them up to date for the purpose of our NZGP Phase One thinking and eventual consultations. We invited industry members to apply to be part of a Scenario Development Panel, which met twice to help us develop these variations. We then consulted on the variations, and then consulted separately on how these should be prioritised.

On this webpage, you will find information about forming the panel, the panel's two online meetings, and the variations consultation.

About the application process and establishment of the Net Zero Grid Pathways Scenario Development Panel

Read our latest industry update 
Scenario Development Terms of Reference (PDF)
Apply to join the Scenario Development Panel (PDF)
Read our industry update announcing the panel.

Online Panel Meeting  5 November 2020

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 (later known as the CUWLP project).


Read the Pre-Reading Document (provided to panellists ahead of the 5 November 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 were treated as written submissions.

Online panel meeting 2 December 2020

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: 


Panel meeting pre-reading clarifications

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

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.

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.

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

EDGS 2019 Variations Consultation and submissions

Consultation document December 2020:

Download the December 2020 consultation document here.


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.

In December 2020 we also issued an update on the Accessing Lower South Island Renewables here.

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.

Submissions received February 2021:

Anonymous submission on Draft EDGS Variations February 2021 Mercury submission on Draft EDGS Variations February 2021 MEUG submission on Draft EDGS Variations February 2021 Trustpower submission on Draft EDGS Variations February 2021