Mercury opens 155MW Kaiwera Downs wind farm in New Zealand

Project is expected to generate 675GWh of electricity annually.

Mercury has opened Stage 2 of its Kaiwera Downs Wind Farm in Southland, completing the South Island’s largest wind farm.

The $486m project took two years to complete and added 36 turbines and 155MW of capacity, bringing the wind farm’s total capacity to 198MW. It will generate an average 675GWh annually, enough to power about 96,000 homes.

Mercury said a 2024 Power Purchase Agreement with New Zealand Aluminium Smelters to support the Tiwai smelter gave it the confidence to proceed with Stage 2.

The project employed 129 full-time equivalent workers, with up to 180 people on site daily during peak construction. Mercury estimates it contributed $100m to the local and regional economy through contractors, accommodation, hospitality, and other services.

Mercury CEO Stew Hamilton said the project was completed on time and on budget.

“We estimate the construction of Stage 2 put $100m into the local and regional economy, through employment of contractors, sub-contractors, support staff, accommodation and hospitality,” he said. “We're also in our third year of supporting the Kaiwera Downs Community Fund, which backs organisations and projects around the wind farm, helping communities make a real difference.”

The company has also started generating power from its Kaiwaikawe Wind Farm in Northland and the Ngā Tamariki Geothermal Station expansion near Taupō. All three projects are expected to be fully operational by the end of 2026, representing about $1bn in investment and 1.1TWh of additional annual renewable generation.

Mercury will next develop the $506m Puke Kapo Hau Wind Farm in Otago, the second stage of the Mahinerangi Wind Farm. The project will have 228MW of capacity and generate about 646GWh annually.

Mahinerangi will become New Zealand’s largest wind farm once complete. Mercury is finalising grid connection studies with Transpower and expects construction to begin later this year.

The company’s decision to proceed was supported by a power purchase option agreement with Datagrid, which is developing a large-scale data centre project in Southland.

Mercury has developed five of New Zealand’s last six wind farms and is preparing to expand its renewable generation portfolio further.