Highlights:

  • Mercury opened a new 55MW generation unit at the Ngā Tamariki geothermal station near Taupō.
  • The $220 million expansion increases the station’s annual output to about 1,120 GWh.
  • New reinjection technology aims to cut the station’s carbon emissions by 70% by 2030.

Mercury NZ Limited (NZX:MCY) has officially launched a major expansion at the Ngā Tamariki Geothermal Station, strengthening New Zealand’s renewable energy capacity. The $220 million project introduces a fifth-generation unit with a capacity of 55 megawatts, more than doubling the output of each of the original units commissioned in 2013. The expansion lifts the station’s annual generation to around 1,120 GWh—enough electricity to power the equivalent of all homes in Christchurch. The project also incorporates new geothermal wells and reinjection systems designed to improve sustainability and significantly reduce carbon emissions in the coming years.

New Generation Unit Enhances Renewable Power Capacity

The expansion at the Ngā Tamariki facility adds a new 55MW generation unit, significantly increasing the plant’s renewable electricity production. The station was originally commissioned in 2013 with four generation units, and the latest addition reflects technological improvements in geothermal power systems over the past decade. The project took less than two years to complete after construction began in 2024.

Mercury Chief Executive Stew Hamilton joined Associate Minister of Energy Shane Jones and representatives from mana whenua Ngāti Tahu Ngāti Whaoa and Tauhara North #2 Trust to formally open the new unit. Around 300 workers, including contractors and consultants from regions such as Taupō, Rotorua, Hamilton, New Plymouth and Napier, contributed to the construction. The expansion increases the station’s annual average generation to roughly 1,120 GWh, helping strengthen New Zealand’s electricity supply and supporting the country’s transition toward cleaner energy sources.

Sustainability and Future Energy Investments

Alongside the new generation unit, Mercury drilled two additional geothermal wells to support long-term sustainability of the reservoir. One well supplies geothermal steam for the new turbine, while the second enables reinjection of geothermal fluids back underground. The improved reinjection system also allows non-condensable gases, primarily carbon dioxide, to be returned to the geothermal reservoir rather than released into the atmosphere.

According to Mercury, the station can now reinject gases across the entire facility, helping the company target a 70% reduction in carbon emissions by 2030. Geothermal energy plays an important role in New Zealand’s power system because it provides steady baseload electricity around the clock, helping meet winter demand and stabilize the national grid.

The expansion is part of Mercury’s wider renewable energy strategy, which includes building two wind farms expected to begin generating electricity by the end of 2026. Together with the geothermal upgrade, these projects represent roughly $1 billion in investment in new renewable generation and regional economic development.

FAQs

  1. What is the purpose of Mercury’s Ngā Tamariki expansion?

The expansion increases renewable electricity generation and strengthens New Zealand’s energy supply while supporting long-term sustainability goals.

  1. How much power will the new unit generate?

The new 55MW unit lifts the station’s annual output to about 1,120 GWh, enough to power the equivalent of all residential homes in Christchurch.

  1. How will the project reduce carbon emissions?

New reinjection technology allows carbon dioxide and other gases to be returned underground, helping reduce the station’s emissions by up to 70% by 2030.