Transpower as System Operator has undertaken analysis to determine what the impacts of the decommissioning of Otahuhu Power Station, Southdown Power Station and the last 2 Rankine generating units at Huntly Power Station will have on operation of the power system and security of supply.
Latest information
On 30 June 2017 we published some options to relieve Central North Island transmission constraints.
Our approach
Over 2015 and 2016 we released a series of reports assessing the impact of proposed and scheduled thermal decommissioning in the Upper North Island.
- We have published the Upper North Island Operational Limits following Huntly Rankine Unit Retirements
- We have updated and published the 2016 Hydro Risk Curves, these are available under the Security of Supply section of the website.
- We have carried out power system analysis on changes to upper North Island power system limits following Southdown and Otahuhu B retirements. See publications below for details of the analysis.
- The November 2015 update of the System Security Forecast update was published on 27th November and includes information about Upper North Island power system limits to the end of 2017, taking into account the decommissioning of Otahuhu B and Southdown. These are available on the System Security Forecast page.
- We have completed an assessment focused on understanding the Security of Supply implications out to 2019, taking into account the decommissioning of Otahuhu B, Southdown and Huntly, this report was published on 9th December 2015. See publications below for details of the analysis.
- We have published The Upper North Island generation decommissioning report: Summary of investigations Stage 1, assessing the potential network impact of proposed and scheduled thermal decommissioning in the Upper North Island.
Any further updates on the impact of thermal decommissioning will be published to this page and communicated to industry.
Publications
 UNI Supply Study - Managing Peak Loads Following Southdown and Otahuhu Retirements [ pdf 1021.21 KB ] (updated 3 Nov 2015) |
| Security of Supply Analysis of Thermal Decommissioning [ pdf 2.55 MB ] (published 9 December 2015) |
 2019 HRC data - All scenarios [ xlsx 26.36 KB ] |
| Thermal decommissioning industry teleconference notes December 2015 [ pdf 68.26 KB ] |
| Upper North Island generation decommissioning report: Summary of investigations Stage 1 (published 15 Mar 2016) |
| Upper North Island Operational Limits following Huntly Rankine Unit Retirements [ pdf 1.3 MB ] (Published 27 Apr 2016) |
