Lake Onslow option

Pumped hydro storage at Lake Onslow is one option being explored.

Facts and figures for Lake Onslow project

The Lake Onslow option referenced by the Interim Climate Change Committee could be anticipated to provide at least 5THh of annual generation/storage. It is estimated to have a construction timeframe of 4-5 years, with commissioning and filling taking a further 2 years. At its construction peak, it is expected to create 3,500-4,500 skilled and semi-skilled jobs.

What services can a pumped storage project like Lake Onslow provide?

  • Fast response reserve—for system stability in the electricity market
  • Intermittency back up—for system security--allows more intermittent wind and solar to be developed once existing hydro flexibility is committed under minimum flows on existing water consents
  • Dry year storage—5-7THh for Lake Onslow alone.

What is the estimated cost of a project like Lake Onslow?

Early estimates of a project like Lake Onslow are that it would cost about $4 billion. A feasibility study will provide greater certainty about the costs.

How would it be funded?

Funding and financing models along with any potential subsequent levies will be determined through the feasibility study.  The use of a levy would need to be justified via a demonstration of significant public good in a feasibility study, including through overall lower prices for consumers in the long term.

Where is the Lake Onslow option located?

The Lake Onslow option is located north east of the Clutha River in Central Otago.

The diagram shows what a 5THh proposed lake would look like at the 760 metre contour. This is not the only possible option for Lake Onslow.

The NZ Battery Project will consider pumped hydro projects at a range of different locations, in addition to alternative technologies.

Map of the 5 TWh/760 metre countour option at Lake Onslow.
Last updated: 22 February 2021