$11.5m contract granted for investigation into Lake Onslow project

Lake Onslow, near Roxburgh. PHOTO: JARED MORGAN
Lake Onslow, near Roxburgh. PHOTO: JARED MORGAN
Several firms have been awarded an about $11.5 million contract to help with the feasibility investigation into the proposed hydro storage scheme at Lake Onslow, in Central Otago.

Minister of Energy and Resources Dr Megan Woods today confirmed the contract was granted to a consortium, Te Rōpū Matatau. This is to be led by Mott MacDonald New Zealand, with engineering consultancy firm GHD, and environmental planning and design consultancy Boffa Miskell. 

“This contract represents a major milestone as it begins the targeted engineering, environmental planning and geotechnical feasibility investigation for Lake Onslow,” she said. 

"The first part of this investigation will look at the design and environmental effects as well as determining the geotechnical fieldwork programme.

“The second part will refine the design, informed by fieldwork investigations of key geotechnical aspects, including the regional geology, rock properties, fault lines and the availability of rock and earth fill at location for potential dam construction. The environmental planning work will look at consenting options and what further work may be needed to assess the environmental effects."

The fieldwork was likely to include drilling boreholes in order to understand the geology, to find the best place for a potential underground powerhouse and the best route for a tunnel.

“This work, along with the environmental and cultural investigations already underway, will give a better picture of the feasibility and costs of the Lake Onslow storage scheme," Dr Woods said.

The minister thanked mana whenua, the community and the landowners around the lake for their patience during the investigation.

The NZ Battery Project is looking at Lake Onslow compared with other energy storage solutions to help alleviate New Zealand’s dry-year electricity problem.

The ‘dry year problem' is when hydro catchments are low and fossil fuels are burnt to generate electricity to cover the shortfall. 

The alternative to this being explored for Lake Onslow is pumped hydro storage, transferring water between two reservoirs at different heights.

Water in the upper reservoir effectively acts as a ‘battery’, as it can be released to generate electricity when it’s needed during times of high demand or during dry years. 

Pumped hydro storage. Image: Supplied
Pumped hydro storage. Image: Supplied

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