• Media release
  • 17 Mar 2022
  • 3 min read

Isolation no barrier for East Coast power project

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  • Isolation no barrier for East Coast power project

Deep in the East Coast bush, a $7.7 million project is underway to squeeze more power from an ageing turbine.

The Piripaua power station is part way through a two-year overhaul of its two generators, first commissioned in 1943.

Nestled between Lake Waikaremoana and Wairoa, the 42MW station is one of three in Genesis’ Waikaremoana Power Scheme, generating electricity for the East Coast and Hawke’s Bay. Kaitawa (36MW) and Tuai (60MW) are further upstream, channelling water from Lake Waikaremoana and recycling it three times through the stations before Piripaua releases it into the Waikaretaheke River.

The Piripaua power station is one of eight in Genesis’ three hydro schemes in Waikaremoana, Tongariro and Tekapo, with a combined generation power of 689MW.

"Piripaua’s turbines were last overhauled 27 years ago. This work will increase their efficiency, or the amount of power they produce from the same amount of water, by 3.3% - a significant enhancement for a hydro station. For a station of Piripaua’s size, that extra 3.3% is enough to power 436 households per year.

The Piripaua power station
The Piripaua power station

Genesis’ Chief Operations Officer Nigel Clark says the project is part of Genesis’ commitment to increase the amount of sustainable generation available to the national grid.

Key to the improvement will be the modernisation of the stay bolts and guide vanes. This was achieved using Computational Fluid Dynamic (CFD) modelling to optimise the flow of water through the turbine. The engineering solution involves retrofitting new stay vanes around the existing stay bolts and manufacturing new guide vanes with a modern profile, "these improvements were largely developed in house by our innovative team members," says Clark.

There will also be a number of safety improvements to eliminate health and safety risks that weren’t considered when the station was built 78 years ago.

Work on the first turbine started in November and will run through till March, then be repeated next year to upgrade the second.

The job requires the expertise of contractors from Taupo-based company MB Century. Covid restrictions might have complicated travel into and out of the area, but a solution was found with Genesis and MB Century establishing eight cabins next to the site. Eight to 10 contractors can stay there on a roster of 12 days on, two days off. All staff and contractors involved in the job are Covid-tested prior to travelling to Piripaua, then tested at regular intervals while on site.

Clark says having the cabins available is a huge advantage in getting the project done safely and on time, "it saves the guys having to go back and forth into the local community and prevents driving fatigue. It’s a bit like camping on site – they only have to walk from the cabins to the station and they’re ready for work."

The Piripaua power station
The Piripaua power station

Genesis and MB Century also came up with a novel contract arrangement. To prevent costs blowing out if other problems were found during the overhaul, and to share costs or savings if the timeframe turned out to be longer or shorter than estimated, clauses were inserted to cover “as found” components, and to allow the two parties to share “pain and gain”.

"This is quite unusual in contracts of this nature. But you don’t know what you’re going to find when you dismantle a turbine for the first time in 27 years, so those clauses protect both parties," says Clark.

The team is having two weeks off over Christmas and New Year. After that, it’ll be back to the bush, upgrading the Piripaua station ready for the next 25 years.

Media contact

Name

Estelle Sarney

Role

External Communications Manager

Company

Genesis

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