After a series of delays, it ended up costing $924m, but on the positive side, the plant’s capacity has increased from the 152MW originally envisaged.
The problems included the need to change parts of the steam separation plant, and fixing underperforming steam-field valves and liquid handling systems.
The station was still experiencing vibration issues recently, but will soon move to its full capacity.
Complex engineering
Geothermal energy is not as simple as sticking a hole in the ground. It involves complex engineering issues and unique problems to overcome at each site.
Prime Minister Christopher Luxon has spoken of the important role of geothermal energy in New Zealand’s energy profile.
A geothermal station provides near-constant base load, aside from maintenance outages and unexpected breakdowns, relieving pressure on NZ’s hydro lakes and thermal plants, which are needed to cover intermittent wind and solar generation.
Tauhara’s addition to the national fleet helped geothermal meet almost 20% of electricity demand during autumn, supplying around 3.5% of NZ’s electricity demand.
It began providing renewable energy to the grid in May 2024 and has been operating at 152 MW since late June.
Contact chief executive Mike Fuge said opening the country’s newest geothermal power station was a watershed moment for Contact and NZ’s decarbonisation.
“Geothermal energy plays a crucial role in creating a reliable supply of electricity. It’s also where New Zealand leads the way with technology and ingenuity, so it’s exciting to expand our fleet of geothermal assets as well as to have two more geothermal power stations on the way.”
International interest
Speaking in Auckland before the station opened, Luxon said there was interest from overseas in NZ’s expertise in harnessing geothermal energy, with delegations from Malaysia and Indonesia due to come to the country.
Tauhara power station opened a week after Contact announced it would build a 101MW geothermal plant, Te Mihi Stage 2, as the first step in replacing its 1950s-built Wairakei geothermal plant. Contact’s seventh geothermal power station, Te Huka 3 is in the final stages of commissioning and will generate enough renewable electricity to power 60,000 homes.
The timing of the rollout should allow Contact to migrate the skilled staff needed from one project to the next.
The power station construction involved 2.65 million work hours by more than 4000 individuals from 27 countries, with on-site labour peaking at 652 people on a single day.
Tauhara derives its power from the world’s largest, single-shaft geothermal turbine.
The biggest blade diameter on the turbine is more than three metres long tip-to-tip. It spins at 3000 revolutions per minute or 50 times a second, with the low-pressure blade tip speed close to the speed of sound.
*This story has been amended to correct the initial cost estimate in paragraph three. The $580m figure first cited in 2021 did not include $98m already spent prior to the final investment decision. The final cost of $924m in the story does include the pre-FID/sunk costs.
