What Snowy Hydro says is happening

The company’s community-updates page is the only current surface it publishes on this, and it is specific. Testing runs overnight for approximately four weeks, weather-dependent, with one generator tested at a time to limit noise and odour. Snowy Hydro says it worked with the turbine manufacturer to cut the time the plant spends at “full speed, no load”, which is the condition that produces the plume. A community team is staffed 24 hours a day, seven days a week through the testing window, on 1800 570 529.

The start date has already moved once. Snowy Hydro had previously said commissioning would begin on or after Friday 10 July; its page now says it is “running a few extra operational checks to ensure we minimise impacts on our neighbours”. Taking the stated schedule at face value, a four-week window opening on 16 July runs to roughly mid-August.

On the plume itself the company is direct: some odour and a visible plume “will occur” during turbine start-up, and it says impacts are being kept “strictly within the EPA’s environmental guidelines”. Once this phase finishes, the station runs primarily on gas, with diesel retained as an emergency back-up, and Snowy Hydro says no visible plume is expected in normal operation.

The line about an investigation

In its own frequently-asked-questions section, answering what the smoke from the stacks is, Snowy Hydro writes that testing involves burning both diesel and gas, that the emissions are a product of full-speed-no-load testing, and then this:

The impacts of our recent testing is currently under investigation and we will communicate as required in due course.

Snowy Hydro, Kurri Kurri Power Station community updates page, last updated 21 July 2026, read 28 July 2026

We are quoting that in full and adding nothing to it. The sentence does not say who is investigating, what is being investigated, or what triggered it, and we are not going to guess at any of those. What can be said is that the operator of a station in final commissioning has published, on its own community page, that the impacts of recent testing are under investigation, and has committed to communicate further. We have asked no one and inferred nothing; if Snowy Hydro publishes more, we will report it.

What the licence permits, and why the hours matter

The most useful number on the page is one that gets very little attention. Snowy Hydro says approval has been granted for the station to operate up to 12.5 per cent of the year, or 1,100 hours, and that the expectation is it will run for less than that.

That single figure explains what this plant is. Kurri Kurri is an open-cycle gas turbine peaker. It is not built to generate electricity most of the time, and it is not a replacement for a coal station in the sense of running around the clock. It is built to start fast and cover the hours when demand is high and wind and solar are not delivering. Snowy Hydro puts the figure it sends to the grid at 660 megawatts, and describes the station’s purpose as allowing more wind and solar into the system. A plant capped at 1,100 hours a year is one that spends at least seven-eighths of the year switched off by design.

This is worth being clear about locally, because a 750 MW gas station arriving in the Hunter invites the assumption that a lot of gas is about to be burned nearby. On the licensed hours, that assumption is wrong in the way most people mean it. The question a peaker raises is not how much it runs. It is what the system pays to have it available for the hours it does.

The market it is arriving into

Here is the context that makes the timing interesting, and it comes from the market operator rather than the company. In its Quarterly Energy Dynamics report for the first quarter of 2026, AEMO recorded gas-powered generation across the National Electricity Market averaging 712 MW, the lowest quarterly average since the fourth quarter of 1999. In the same report Kurri Kurri was the only NSW gas station with higher output than the previous quarter, up 14 MW, because its second unit began commissioning in December 2025.

So a new gas peaker is finishing construction at the point where gas generation across the market is the weakest it has been in more than a quarter of a century. Those two facts sit together more comfortably than they first appear, and the reason is the same 1,100-hour cap. Falling gas volume and rising demand for fast-start capacity are not in conflict. As coal leaves the system, the hours that need covering get fewer and sharper, which is exactly the shape a peaker is built for. Our own view, offered as a view: judging this station by how much electricity it produces will mislead you, and the honest measure is whether it is available and how often the system actually calls on it. Those are numbers we will be able to check once it is operating, and we intend to.

Two Hunter assets finishing at once

Kurri Kurri is not the only thing being finished in the valley this month. AGL’s 500 MW, two-hour Liddell Battery, on the site of the closed Liddell Power Station, has completed construction with “full commercial operations expected by July 2026” on AGL’s own page, which still read that way when we checked it on 28 July with three days of the month left. We tracked that date across AGL’s own statements earlier this month, as it moved from early 2026 to June to July.

A 660 MW fast-start peaker and a 500 MW two-hour battery, both reaching operation in the same few weeks, on and beside the ground where the Hunter’s coal fleet is winding down. That is the replacement fleet arriving, and it is arriving as two quite different products: one that burns fuel when called, one that stores what the grid has already made.

A note on the regulator’s public register

We tried to check the station’s Environment Protection Licence directly, since that is where the air-monitoring conditions live. We could not, and the reason is worth recording. The NSW EPA’s POEO public register is mid-migration, and carries its own notice that during the transition “some information on our current site will only be accurate as at 28 April 2026”. The licence-view page for this premises redirects to the search screen. So the register cannot currently speak to anything that happened in July, and any reader or reporter who checks it and finds nothing recorded should not read that as evidence of nothing having happened. We will re-check when the new register is live.