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South Island's largest wind farm opens in New Zealand

South Island's largest wind farm opens in New Zealand

Built World

Mercury's Kaiwera Downs project is one of three renewable developments totaling $1 billion in investment

Today: Kaiwera Downs Wind Farm officially opens

Overview

Updated 1 hour ago

Mercury opened the Kaiwera Downs Wind Farm near Gore on Wednesday, the South Island's largest. The $600 million project's 46 turbines generate 675 gigawatt-hours a year, enough to power 96,000 homes.

The opening is part of a larger buildout. Mercury has three renewable projects totaling about $1 billion in investment and 1.1 terawatt-hours of annual generation, enough for 160,000 homes. Two more large wind farms are in the pipeline for the South Island.

Why it matters

New Zealand is adding renewable generation at scale to replace fossil fuels and power new data centres, with the South Island at the center of the buildout.

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Key Indicators

$600M
Total cost of Kaiwera Downs Wind Farm
Completed in two stages, with stage two costing $486 million.
46
Turbines at Kaiwera Downs
Stage two added 36 turbines to the original 10.
96,000
Homes powered by Kaiwera Downs
Annual generation of 675 gigawatt-hours, up from 146 GWh in stage one.
$1B
Combined investment in three Mercury renewable projects
Kaiwera Downs 2, Kaiwaikawe Wind Farm, and Ngā Tamariki Geothermal expansion.
160,000
Homes powered by the three Mercury projects
1.1 terawatt-hours of additional annual renewable generation.

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People Involved

Organizations Involved

Timeline

2024 September 2026

7 events Latest: Today
Tap a bar to jump to that date
  1. Kaiwera Downs Wind Farm officially opens

    Today Milestone

    Mercury opened the South Island's largest wind farm near Gore, completing a $600 million two-stage project.

  2. Mercury approves $506M Puke Kapo Hau investment

    Investment

    Mercury's board approved the 192-megawatt Puke Kapo Hau wind farm, construction expected before end of 2026.

  3. Puke Kapo Hau receives fast-track consent

    Regulatory

    Mercury's 40-turbine Puke Kapo Hau wind farm west of Dunedin received fast-track approval.

  4. Southland Wind Farm gets fast-track approval

    Regulatory

    Contact Energy's Southland Wind Farm received fast-track consent for a 380-megawatt project.

  5. Mercury signs power deal with Datagrid

    Agreement

    Mercury signed a 140-megawatt power purchase option with Datagrid for its Southland data centre.

  6. Contact Energy lodges Southland Wind Farm application

    Regulatory

    Contact Energy filed its application for a 55-turbine wind farm in eastern Southland.

  7. Mercury signs Tiwai smelter support agreement

    Agreement

    Mercury signed a Tiwai smelter support agreement, enabling Kaiwera Downs stage two.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

1971-present

Tiwai Point Aluminium Smelter (1971-present)

The Tiwai Point smelter near Bluff opened in 1971, built to use power from the Manapouri hydro scheme. It consumes about 13% of New Zealand's electricity and has repeatedly threatened closure over power price negotiations, most recently in the 2020s.

Then

In 2024, Mercury signed an agreement to support the smelter, providing near-term certainty and enabling the Kaiwera Downs stage two expansion.

Now

The smelter's future remains uncertain. If it closes, Southland would have a large electricity surplus, potentially affecting the economics of new wind farms in the region.

Why this matters now

The smelter's power demand is a key reason new wind generation is being built in Southland. Its potential closure is a major variable in the region's energy planning.

2006-2026

Mt Cass Wind Farm (2006-2026)

First proposed in 2006 by North Canterbury lines company MainPower, the Mt Cass Wind Farm faced repeated setbacks over two decades. In 2026, Malaysia-based Yinson Renewables bought the project and Genesis Energy agreed to buy 70% of its output, clearing the way for construction of 22 turbines generating close to 100 megawatts.

Then

Construction is expected to start in early 2026 with completion in 2028.

Now

The project shows how long wind farms can take in New Zealand without fast-track approvals, and how new ownership and power purchase agreements can revive stalled projects.

Why this matters now

Mt Cass took 20 years from first proposal to construction. The fast-track approvals granted to Kaiwera Downs, Puke Kapo Hau, and Contact Energy's Southland Wind Farm are designed to compress that timeline dramatically.

Sources

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