23 March 2020 - A $67 million project on Mercury’s Whakamaru power station has future proofed the station and increased output by over 20% (from 100MW to around 124MW) - enough to power an additional 12,700 electric vehicles.

  • $67 million investment, 12 years planning and execution including over 4 years on-site works
  • the most complex project to date in Mercury’s multi-year re-investment across the Waikato Hydro System, with a quarter of a billion dollars re-invested so far
  • increased output – enough to power an additional 12,700 electric vehicles
  • increased ability to rapidly respond to peak demand requirements for the National Grid

“Whakamaru power station is a critical piece of infrastructure, in a pivotal position in the highly integrated cascade hydro system on the Waikato,” says Phil Gibson, GM Hydro Wholesale.

The upgrade will result in a 20% gain in the peaking capacity of the station (the ability to rapidly respond to peak demand requirements). This will become increasingly valuable as New Zealand decarbonises its economy, and the addition of intermittent renewables such as wind require complementary rapid peaking capacity provided by other renewables such as reliable hydro generation.

Whakamaru power station is located 40km north of Taupo and was commissioned in 1956. With the station reaching a stage in its life cycle where the generators and turbines required replacement, Mercury’s engineers saw opportunities to get more power more sustainably from the station.

“We’ve been thinking for over a dozen years about how to get greater efficiency and more power from the water that passes through this station. We’re very pleased with the results,” says Phil.

All four turbine units have been completely overhauled. Only one of the four had been completely opened up and refurbished in the past 60-odd years, so some parts of the machinery were touched for the first time since, a tribute to by the Kiwi women and men who originally built the station. The major components of the new installed equipment have design lives of 50 years.

“Everything about this project has been big – the timeframes, the money, planning, the size of the parts, the complexity, the risks, and the expertise of our teams,” says Phil.

There were some very big boxes delivered to site during the project: 4x 22-tonne stainless steel turbine runners, 4x100-tonne generator rotors with 176 new poles, and 4x85-tonne stators. It’s been a truly global endeavour with design and manufacture in Austria, Italy, China, Poland, Switzerland and Spain.

Despite the huge machinery involved, the project was injury free. Unit outages were scheduled over summer months to lessen impact on the market of reduced generation at the station. During the five-month installation of each unit there were up to 40 people on site, six days a week, with work crews from the local area and the South Waikato/Taupo region. A celebration is planned, including some of the original team who built the station back in the 1950s.

This milestone is part of an extensive programme to secure the operational efficiency and effectiveness of the hydro system for future generations. Ohakuri, Arapuni, Aratiatia and now Whakamaru power stations have received significant re-investment – a total of a quarter of a billion dollars so far. Next up: detailed design and manufacturing is underway for a full-scale $75m overhaul of the Karapiro power station, with hands on tools onsite from next year.

“Our multi-year reinvestment programme will secure the ultra-long-term future of the Waikato Hydro System. This will play a very important role in complementary future wind development as New Zealand continues to decarbonise its economy,” says Phil.

Watch a time lapse of the upgrade of the second Whakamaru Generator and Turbine: 8 months’ work in 30 seconds here.

For further information:
Media – Katy Scoullar 0272 105 337
Investors – Tim Thompson 0275 173 470


Mercury’s mission is energy freedom. Our purpose is to inspire New Zealanders to enjoy energy in more wonderful ways and our goal is to be New Zealand’s leading energy brand. We focus on our customers, our people, our partners and our country; maintain a long-term view of sustainability; and promote wonderful choices. Mercury is energy made wonderful.

Visit us at: www.mercury.co.nz