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Second power generation unit nears completion at Karāpiro hydro station
12 JULY 2024 – Mercury has reached a major milestone in its three-year, $90m upgrade of the Karāpiro Hydro Power Station on the Waikato River.
The company is about to commission the second of three new power generation units, with work on the third and final unit expected to begin in October. The generation units house components, such as hydro turbines, which make electricity from the water’s force.
Mercury Executive GM Generation, Stew Hamilton, said bringing the second power generation unit online is a significant step towards completing the major upgrade.
“When upgraded, the Karāpiro hydro station will provide an additional 5MW per generation unit. This will increase its capacity from 96MW to 112.4MW (32GWh/year), enough to power 19,000 homes with renewable energy.”
He said Mercury is working with its specialist project partner ANDRITZ Hydropower to ensure the generation units are installed efficiently and seamlessly.
“Maintenance and enhancement of our hydro stations is important as we work towards helping the country move towards greater use of renewable energy.”
Heavy machinery will be used to install a new 40-tonne water intake gate at the top of Karāpiro dam, on Monday, 15 July.
The gate is an important safety element to protect the new generator. It is the second of three gates that are being replaced because they have reached the end of their life after more than 75 years of operation.
All three gates are being constructed and installed by Ashhurst Engineering and Construction. Each gate took six people about a year to fabricate. The gates are 8m wide, 6m high and 0.75m deep.
A special trailer will transport the new gate to the dam and fit it into place. After installation, the gate will undergo testing before coming online in late August. Full installation and commissioning of all units is expected by August 2025.
It is the first time the power station’s generation units have been replaced since the station was commissioned in 1948. The upgrade will enable Karāpiro to continue to generate renewable energy for the next 50 years.
"Our nine hydro stations on the Waikato River had been working hard to keep New Zealand powered, some for more than 75 years,” Mr Hamilton said.
“So for nearly a decade we’ve had significant investment in refurbishing our stations and that will likely continue over the next 15 years.
“We want to protect these assets to ensure they can manage water flow in a way that looks after the environment but can also optimise energy from the awa.”
The road across the top of Karāpiro dam has been closed since 2022, to allow Mercury to investigate the best way to replace and install the power station’s generation units.
Mr Hamilton thanked the Karāpiro and neighbouring Cambridge communities for their patience while the road was closed.
“We understand the road is used as a key route for people living and working in the area and many recreational users of the lake.
“We appreciate the community support we’ve had as we gather pace towards completing this work in 2025.”
ENDS
For media inquiries, please contact: Lawrence Gullery Communications & Engagement Manager 027 801 0200
mercurycommunications@mercury.co.nz
ABOUT MERCURY NZ LIMITED
Mercury generates electricity from 100% renewable sources: hydro, geothermal and wind. We are also a retailer of electricity, gas, broadband and mobile services. We’re listed on the New Zealand Stock Exchange and the Australian Stock Exchange with the ticker symbol ‘MCY’, with foreign exempt listed status. The New Zealand Government holds a legislated minimum 51% shareholding in the Company.
Visit us at: www.mercury.co.nz