On Wednesday 27th August 2025, I noted ‘Several coal units offline (on Wednesday 27th August 2025) with unplanned outages’.
… Since that time we’ve posted several articles about an unplanned outage at Yallourn unit 2 due to ‘LP turbine issues’, but have not had time to explore others further.
In this particular article, however, I’d like to look at another unit – the Vales Point unit 5 in NSW.
A look at VP5 in the AEMO data
In the article from 9 days ago, the ‘Generator Outages’ widget showed that (at that time) the expected return to service for Vales Point unit 5 was sitting next Wednesday 10th September 2025. However in glancing at the same ‘Generator Outages’ widget in ez2view just now:
1) I see that the expected return to service has pushed out to Sunday 9th November 2025;
2) Which is (obviously) adding a big extension (of ~2 months)
3) Though I would caution readers that there’s some nuance in interpreting this, as I will explain.
Firstly, here’s the first ez2view snapshot, as at the 11:50 (NEM time) dispatch interval on Friday 5th September 2025:
As noted on the image, the expected return to service (out 65 days into the future) is clearly beyond the capability of the visible window. We could scroll, but a different way to show what you’d see if you scroll can be seen in the ‘Forecast Convergence’ widget snapshot here:
Remember that this widget allows one to ‘look up a vertical’ in order to see ‘that other dimension of time’ . In this case, the widget is configured to show 3 years backwards and 3 years forwards in the MT PASA DUID Availability data set, filtered to VP5.
With this in mind, my interpretation of what we see in the 2 images is that:
1) The generator had a major planned outage slated for VP5 sometime during September-October 2025
… note that it’s been common terminology to classify outages as either:
(a) ‘Major’ (if the work entailed might take 4 weeks or longer – say)
(b) or ‘Minor’ (if the work entailed might only be a week or so)
… though there is no hard-and-fast rule for terminology.
2) For reasons not yet explored, the unit came off earlier than planned (on Tuesday 26th August 2025) under an unplanned outage
3) Subsequently, a decision has been made:
(a) The decision made was not to bring the unit back online and then take it off again shortly afterwards as had initially been indicated:
i. but rather, to continue the unit outage through until the end of whatever was already lined up for the Major Planned Outage;
ii. this decision is understandable, given that September-October ‘normally’ could be expected to see generally subdued prices in any case
iii. and it may allow for re-arrangement of work schedules to save outage cost:
> i.e. not working so many contractors 24×7 through a compressed outage period
> but that bit is just speculation on my part.
(b) Note that we can’t tell from the data the extent to which both factors played in the decision:
i. it might be that the problems triggering the unplanned outage warranted a longer outage; or
ii. it might be that the (relatively) low commercial return, and risks of coming on and then off for a relatively short period justified merging the outages
(c) What we can tell (from the zoomed in view of the ‘Forecast Convergence’ widget below) is that:
i. it was ~48 hours ago (on Wednesday 3rd September 2025) that the decision to merge the outages was made
ii. and the market informed, via the MT PASA DUID Availability data set at AEMO:
There still remains a question (at least for me) – what brought the unit offline in the first place. In this case the place to look (in amongst the AEMO data) is in the bids and rebids, through the ‘Bids & Offers’ widget in in ez2view as follows:
I’ve annotated to highlight a couple things:
1) On Monday 18th August 2025 the unit came off for an earlier unplanned outage (at least in part due to a ‘tube leak’) with return to service achieved on Sunday 24th August 2025;
2) But then on Tuesday 26th August 2025 the unit came offline, with rebid reasons suggesting that ‘turbine vibrations’ were a factor.
That’s all I have time to look for in the AEMO market data at that point … but another outage to watch in the weeks ahead.
Elsewhere?
I did quickly look at the ‘News’ page of the Delta Electricity website, but did not see anything there. Nor have I seen anything else elsewhere.
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