Ngāwhā - Full Steam Ahead
When you hear the word “Geothermal” you probably think Rotorua or Hanmer Springs.
Until now, there has been low public awareness of the existence of the Ngāwhā Geothermal Power Station, hidden away in the North Island’s Far North
With a significant expansion project underway that will see the power station double in size by mid-2020, that’s all about to change.
New Zealand’s always been a world leader in the renewable energy sector - establishing our first (and the world’s second) large scale geothermal plant in 1958. Fast forward to 2019, and we currently produce roughly 93% of our electricity from green sources, with the current government aiming for 100% by 2035.
This isn’t quite as easy as you’d imagine. Since battery technology is only starting to tackle the issue of creating massive capacity, short term storage, batteries, our energy generation must constantly match demand, to ensure there’s enough power to go around.
Hydro-power has been ideal, in that the water storage means the energy is stored behind the dam and electricity can be generated on demand. However, our forebears developed all the plum hydro-power sites many years ago leaving little opportunity for cost-effective and environmentally friendly expansion.
Thus, extending our renewable energy generation capacity largely relies on solar, wind and geothermal generation. Wind and solar are reliant on the instantaneous weather, or to state the obvious, solar generation produces no power at night.
Geothermal energy is widely touted as the solution to this problem. The Earth’s core doesn’t stop at night or on a windless day and, in New Zealand, we have plenty of thermal hot spots at shallow depth that are potentially accessible and can sustain consistent, base-load electricity generation. The $176m Ngāwhā Geothermal Plant expansion will add 31MW of capacity, more than doubling the current output of the facility.
As always, there’s a catch. You can’t choose where you put your geothermal plant, Mother Earth already narrowed your options. And then you must work with the terrain surrounding the vents – which is typically disturbed land with substantial variations in properties over short distance and this isn’t always ideal for construction.
That’s where Tonkin + Taylor (T+T) comes in.
“T+T is involved in the civil design, and managing the civil construction contract with United Civil Construction (UCC) on behalf of Ngāwhā Generation Limited”, says T+T’s Ngāwhā Project Director and senior civil engineer Keith Dickson.
“This project has particularly challenging ground conditions. Multiple, large scale, level, platforms had to be formed and made suitable for the rapid construction of a kitset power plant by the next contractor - a pretty big job to say the least.
“T+T, Ngāwhā Generation and UCC approached the construction project from a partnering perspective and cooperated to tackle the problem head-on. The design team has worked one step ahead, most of the time, of the ongoing civil works, allowing problems and scope changes to be addressed collaboratively and in a timely fashion. As a result, the project is currently on track to be delivered well ahead of the contracted schedule.
Once the plant is operational, Northland will become substantially more self-sufficient. Currently a net importer of electricity, after the Ngāwhā expansion is operational it will produce enough electricity to meet 90% of Northland’s power demand.
“It’s one of those projects I’ll be proud to share with my grand-children”, says Keith.
Interesting, challenging, legacy projects, like Ngāwhā, are the reason our engineers, planners and scientists get out of bed in the morning.
For more information, contact T+T's Ngāwhā Project Director, Keith Dickson