Upgrade for Key Waikato Hydro Station

21 October 2011
Ohakuri Hydro Station - Overhead of turbine housing.A rare opportunity to see the inner workings of one of Mighty River Power’s Waikato hydro stations presented this week, when one of four generating units at Ohakuri was opened up as part of an upgrade to receive a new water turbine after 50 years’ reliable service.

The 106MW Ohakuri station (with an annual output of around 400GWh/year) is a core part of the Waikato Hydro System which produces around 4,000GWh/year, and is the North Island’s most significant source of hydro generation.

Mighty River Power, which operates the Waikato Hydro System as well as 2,200GWh of geothermal production and multi-unit gas generation, is undertaking a re-investment programme in the Waikato Hydro System of around $500 million over the next ten years. The programme will deliver increased efficiency and capacity and support the reliable operation of the assets as part of the Company’s flexible generation portfolio.

Four 26-tonne water turbines, from technology leader Toshiba in Japan, are being installed by both Toshiba and MB Century over the next two years as part of a $28m refurbishment and upgrade project at Ohakuri. General Manager Operations, Fraser Whineray, said Mighty River Power’s hydro system assets have been reliably operating for many decades, and the focus was on ensuring the highest levels of efficiency, future availability and reliability of the hydro generation assets.

“The pioneers of the Ohakuri hydro station which commenced operations in 1961 did a tremendous job with the efficiency and reliability obtained. Modern technology allows us to lift performance and capture more electricity from the same amount of water. Water is a scarce and precious resource and its efficient use is imperative,” he said.
Mr Whineray said, at their peak, the original runners operated at efficiency levels of approximately 89%. The replacement with new equipment will see efficiency rise to around 96% and increase current generation output by more than 28GWh per year on average – enough for around 3,500 homes.

Photo: Ohakuri Hydro Station – Overhead of turbine housing: Fraser Whineray, Mighty River Power - GM Operations Chris Staal, Mighty River Power - Station Services & Auxiliary Systems Team Leader. Supplied by: Jeremy Bright at GRABB.