Onslow pumped storage

Pumped storage at Lake Onslow is presently under investigation by the NZ Battery group as one of a number of possible options for a dry year buffer. This is aimed to sustain a future low-emission electrified economy powered by 100% renewable electricity.

Given the allocated expenditure on various aspects of the Onslow ecological and geological environments, it is a reasonable deduction that Onslow pumped storage is the lead contender. However, information released on Onslow by NZ Battery has been minimal to date. Also, the completion of the Phase 1 investigation and its public release by MBIE has now been set back to the end of 2022, although some government statement is due in May.

Aside from NZ Battery, the only publicly available information on Onslow has been media items of variable quality, and technical thesis and scientific publications from the University of Waikato.

Later in the year, there will be reports released by NZ Battery on Onslow pumped storage with respect to engineering, environmental, and cultural aspects. In the meantime, as an aid to discussion, it is possible to make an informed estimate as to how the scheme might be set up and consider associated possibilities. Those interested can download a pdf file here, which covers the topics in the list below to varying degrees of detail. The file includes some material previously displayed at this site. A useful brief Onslow overview can be found in a media item here.

Present topics in the downloadable file:

* What is pumped storage?
* A quick revision on units
* What would Onslow pumped storage look like in the local landscape?
* How will Onslow pumped storage link to the Clutha River?
* How would Onslow pumped storage operate?
* Could pumped Onslow water be lost through evaporation and leakage?
* Could Onslow pumped storage dry up or flood the Clutha River?
* Why have the major generators been publicly opposed to Onslow pumped storage?
* Is Lake Onslow pumped storage economic?
* Will Onslow pumped storage result in higher electricity bills?
* How long will Lake Onslow take to fill (and refill)?
* Where will the initial energy come from to bring Onslow to operating level?
* How long would Onslow pumped storage remain operational?
* What would be the major environmental impacts of the Onslow scheme?
* Otago water resource and environmental opportunities

Earl Bardsley, University of Waikato, 2022