UPDATE
The third and final stage on the Karāpiro Hydro Station refurbishment project began in October 2024. / Photo: ANDRITZ
Mercury is reaching the midway point in a major 26-year programme to refurbish its nine hydro stations, helping to improve the country’s security of supply.
The company has so far invested $628 million in completed or planned work to enhance the resilience and performance of seven of the hydro power stations on the Waikato River.
More investment decisions are likely soon for three more hydro stations as part of a programme of work which started in 2012 and will be completed in 2038.
Mercury’s Head of Operations – Generation, Matt Kedian, said the significant long-term investment recognised the important role the Waikato Hydro System played in delivering renewable energy for Aotearoa New Zealand.
“The nine hydro stations were constructed on the Waikato River from 1924 to 1970, and they have helped to keep New Zealand powered for decades.
The final of the three new turbines is fitted into the new generation unit at the Karāpiro station.
“Mercury and others before us, have invested heavily over those years to care and maintain the hydro system.”
About 40% of the electricity Mercury produces is generated by its hydro system, delivering around 10% of New Zealand’s electricity, an average of 4000GWh each year. That’s enough to power about 500,000 average homes.
“Our refurbishment programme will allow us to operate our hydro stations safely and efficiently for many more years to come.”
To date various upgrades have been completed at Arapuni, Ōhakuri Turbines, Aratiatia and Whakamaru hydro stations, which have improved efficiency or increased MW output, depending on the work done.
Mercury’s Hydro Rehabilitation Programme Manager, John Kennedy, said the focus is now on completing the three-year, $90 million upgrade of the Karāpriro Hydro Power Station.
Karāpiro Hydro Station has been generating renewable energy for New Zealand since 1947.
ANDRITZ, an international specialist in hydro station upgrade projects, is leading the work at Karāpiro and the project is on track for completion by September 2025.
Karāpiro was the third power station built for the Waikato Hydro System; it has supplied power to the national grid since 1947.
When the upgrade is completed, the station will have an additional 16.5MW, taking installed capacity from 96MW to 112.5MW.
That will increase its average annual output by 32GWh to 537GWh, enough to power an extra 4000 average homes. In total, it’ll be able to power about 63,000 average homes when all three new generators are operational.
Maratai Hydro Station is one of three, with Atiamuri and Ōhaukuri, where proposed rehabilitation projects are planned.
“These upgrades will enable Karāpiro to generate more electricity from the same volume of water and it will also ensure the hydro station can contribute to New Zealand’s renewable energy supply for another 50 years.”
It will lift energy generation by about 85GWh per year between the three stations, enough to power about an extra 10,600 average homes.
Mr Kennedy said like Karāpiro, the upgrades will ensure the hydro stations can continue to generate power for at least another 50 years.
“And every 25 years the hydro stations will have a mid-life refurbishment to ensure they can reliably help meet the renewable energy demands of New Zealand.”
The upgrade work completed to date showed Mercury and its project partners had a good track record for caring for the hydro system.