Ngā Tamariki Geothermal Station

Ngā Tamariki Geothermal Station is bordered by farmland to the east and west, and the Waikato River along the northern and southern boundary.

Ngā Tamariki Geothermal Station

Our Ngā Tamariki Geothermal Station is 17km northeast of Taupō. The station is 100% owned by Mercury and produces baseload energy 24/7 for the country.

The geothermal resource has been developed with iwi partners Tauhara North No.2 Trust. The trust jointly owns the resource consents and receives a revenue stream from the station and has options to take an equity stake in the station.

Tauhara North No.2 Trust is also a joint venture partner on the Rotokawa Geothermal Field and Ngā Awa Pūrua Geothermal Station.

The geothermal reservoir is located on the Wairakei Pastoral Estate and land is leased for the development of the geothermal station which co-exists alongside the farming operations.

Investigations into potential geothermal development at Ngā Tamariki began with the Crown drilling four exploration wells in 1985 and 1986. A further three wells were drilled by Mercury in 2008 and 2009, prior to station construction commencing in 2011.

The station was commissioned in 2013, comprising four energy generation units.

It was built with allowance for expansion, once the capacity of the geothermal reservoir was explored and understood.

Ngā Tamariki currently has seven operating geothermal wells extending depths of more than 3000 metres, which reach up to 290°C. This will increase to nine when the station’s expansion project is completed.

The station just after work started on the expansion in May 2024.

Progress made, with the new generation unit about 80% complete in September 2025.

Expansion project

Mercury completed prefeasibility investigations into an expansion project at Ngā Tamariki in late 2021. Consenting, planning, specification and procurement then followed through until September 2023. A recommendation was then made to Mercury’s Board of Directors to approve the project and enter into the main supplier contract. 

Physical work on the two-year, $220 million expansion, began in May 2024 and it is on track to be commissioned by March 2026.

The project involves adding a fifth energy generation unit to the station, increasing installed capacity by 46MW, moving from 86MW to 132MW.

This will increase annual average generation output by 390GWh, that is the equivalent of enough power for about 55,000 homes, about the same as the number of residential homes in Tauranga city.

The total annual average generation output for the station, when the upgrade is completed, will be about 1120GWh. That’s enough to power the equivalent of 158,000 average homes, greater than all of the residential homes in Christchurch.

We developed the project with our commercial partner Tauhara North No.2 Trust and with mana whenua Ngāti Tahu Ngāti Whaoa to ensure the sustainability of the geothermal reservoir and management of the surrounding environment.

More than 300 people have worked on the project from Mercury, and contractors and consultants from Taupō, Rotorua, Hamilton, New Plymouth, Napier and beyond. 

Read more about one of our Project Engineers - Lexi Richards 

Carbon reinjection
Ngā Tamariki is also where we successfully trialled a method to reinject non-condensable gases (NCGs), which are mostly from carbon dioxide, back into geothermal reservoirs, rather than releasing the gas into the atmosphere.