Lake Onslow, New Zealand, could become home to one of the world’s largest pumped-hydro storage facilities. A local consortium is now conducting a feasibility study and is investigating possible system designs and precise locations.

Rōpū Matatau, a consortium led by engineering consultancy Mott MacDonald New Zealand, plans to build a pumped-hydro storage facility on Lake Onslow, New Zealand.

The group of companies, which also includes engineering consultancy GHD and environmental planning and design consultancy Boffa Miskell, recently secured a contract to investigate the engineering, environmental planning, and geotechnical feasibility of the project.

During the project’s first phase, the consortium will evaluate the feasibility of different pumped hydro configurations at the lake and other possible locations around the country. It will also consider different pumped hydro systems as a technical solution to resolve New Zealand’s “dry year problem.” In addition, it will investigate the nearby availability of materials for dam construction, the geology of the possible dam wall area, tunneling costs, early geotechnical details, and environmental and cultural impacts.

“The Lake Onslow option referenced by the Interim Climate Change Committee could be anticipated to provide at least 5 TWh of annual generation/storage,” the government said. “It is estimated to have a construction timeframe of four to five years, with commissioning and filling taking a further two years”

In the second phase, Rōpū Matatau will perform geotechnical and engineering field work, analyze local geology, and determine the exact location of the project.

“Te Rōpū Matatau has been granted resource consents and other permits to undertake geotechnical, geological and hydrogeological investigations, which will inform the Lake Onslow feasibility study,” the government said.

Preliminary work began at the first site in April and is expected to continue at various times throughout the year at a number of sites near Lake Onslow. The feasibility study will likely be concluded by the end of the year.

According to New Zealand’s University of Canterbury, the pumped hydro storage facility could have a head of 650 meters and a “very large” storage capacity. It would also require an atypical scheme design, due to the 20 km distance from the Clutha River.