Talking about data centres....NZ came close to a blackout last night
I suggest sharing this information with anyone who has ears to listen and a mind to think.
Transpower is warning of higher risks of electricity outages starting in winter 2026.
The national grid operator’s draft Security of Supply Assessment predicts an elevated risk of shortages will arrive four years earlier than thought as recently as a year ago.
It found solar, wind and battery storage isn’t coming online fast enough to make up for dwindling supplies in the country’s gas fields.
The assessment found, if every electricity generation project in the pipeline was built, supply would be much more reliable, but Transpower said there was a risk of some proposed solar, wind and battery projects falling over.
https://www.rnz.co.nz/news/business/561157/transpower-warns-of-higher-blackout-risk-in-winter-2026
Pay attention to this
Near miss.
Did the NZ grid have a close call last night?
Aug 04, 2026
“A control room is 99% routine and 1% controlled chaos. That 1% is what you’re paid for.”
I was warmly ensconced in my office last night filling out a form, a banal activity whose cumulative effects will result in many years my life lost, when a friend messaged me to take a look at the wholesale power price.
Welcoming a distraction from the tedium of form filling, I promptly turned my attention to the very helpful em6 dashboard to see what was happening.
Sure enough I found a dramatic spike in the prices just after 7pm last night. My immediate thoughts were that this was odd as peak evening winter load usually occurs earlier in the evening, typically around 5-6pm.
My curiosity piqued I turned to the Transpower consolidated live data dashboard.
Here I found the total generation at a high level of 7.2GW. In similar circumstances to those covered in my recent piece “Power Matters”, hydro and geothermal were again pretty much maxed out, this time there was also some wind in the mix luckily, and again it was what was missing that was the most interesting.
There was no coal fired generation in the mix?
I found this curious as coal is nearly always in the mix on cold winter evenings to ensure we have sufficient reserve capacity to prevent the grid falling over if something trips. Something definitely wasn’t right.
With a bit more digging I noticed an excursion notice from Transpower showing that Huntly had tripped at 7:45pm resulting in low frequency excursion. The North Island grid frequency dropping to 49.24Hz, which is below than the 49.5Hz lower limit for normal operations.
A low-frequency event is one of the most serious disturbances that can occur on an AC power system because frequency is the clearest indicator of the balance between generation and demand. If the frequency were to fall to 47.8Hz the system automatically sheds load, which would have been experienced as a blackout for parts of the North Island.
Thankfully last night we had a lot of heavy synchronous rotating generation on the grid at the time in the form of geothermal and hydro generation. This mechanical inertia would have helped to prevent the frequency falling further immediately after the trip.
Seconds later as the inertia dissipated the grid would have called on instantaneous reserve generation to pick up the load and stabilise the grid. I suspect that gas turbines would have been critical to providing this instantaneous reserve capacity.
My immediate sense, in the absence of more high resolution data, is that we came very close to a blackout on parts of the grid last night.
More information about this event will emerge over the coming days and I will update this piece accordingly if it provides additional insights.
The key take away is again that energy may keep the lights on over the course of a winter, but it’s dispatchable power, inertia, and fast frequency response that keep the lights on over the next ten seconds.
Finally, a tip of the hat to the control room operators across the country. Most days their work is routine and largely invisible. Last night was almost certainly part of the 1%, when calm decision making over a hectic few seconds keeps the rest of us blissfully unaware that anything happened at all.
P.s.
If you have any further insights regarding this event I’d love to see them in the comments.
Thanks as always.
Larry