The race that stopped the nation … and electricity demand

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Melbourne Cup caused NSW demand to “fall off a cliff”, down 1,000MW in minutes. But the grid coped fine, as it can with supply changes.

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(Note: This story has been updated to reflect the sudden fall in demand was due to outages at the Tomago aluminium smelter).

The anti-renewable lobby love to complain about the intermittency of “variable” renewable energy sources such as wind and solar, saying that it is impossible to manage on a large grid.

But there’s nothing quite so variable as demand … and the grid operator has been handling it just fine, as it has done for decades.

Just minutes before yesterday’s running of the Melbourne Cup there was a 1,000MW “cliff” in the NSW grid, as demand was suddenly lost.

melbourne race

It was first speculated that it was because of disappearing demand as punters took leave of their work stations and work places wound down. Turns out it was a sudden “trip” at the Tomago aluminium smelter which took three pot lines and more than  930MW of demand out of the system

As the graph shows, demand went from more than 8,200MW to less than 7,200MW in the space of five minutes, before gradually recovering over the next hour.

By the way, the big fall in demand on the previous day – though gradual – is an example of the so-called duck curve, where rooftop solar hollows out demand in the middle of the day, once one of the most profitable parts of the day for fossil fuel generators.

One of the differences between wind and solar and fossil fuels is that while the changes in output in wind and solar are quite predictable, sudden outages from coal and gas-fired plants and industrial users are often not.a

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9 Comments
  1. Jacob 4 years ago

    Giles, the race was in Victoria, why are you talking about the NSW demand?

    Or is it because yesterday was a public holiday in MEL and so offices were closed.

    • John P 4 years ago

      Or it could be that people who live in Sydney are not aware that Australia extends beyond Sydney’s boundaries.

    • Giles 4 years ago

      i reckon there are a couple of people in NSW interested in the race. as you suggest, public holiday in Vic so no change in demand.

      • Jacob 4 years ago

        Where do you live Giles? 🙂

    • Paul McArdle 3 4 years ago

      Jacob

      The chart included in this post also shows a few days for VIC demand – you can see in this lower demand for VIC on the Melbourne Cup day:

      http://www.wattclarity.com.au/2015/11/it-wasnt-the-horse-race-that-led-the-large-drop-in-load-in-nsw-coincident-with-the-race/

      This would be due, at least in part, to public holiday

      Paul

      • Jacob 4 years ago

        The WattClarity article says the horse race did not cause a dip in NSW demand. But then does not say what did.

        • Paul McArdle 4 years ago

          Thanks Jacob

          When I posted on WattClarity yesterday, I was aware of the cause – but was not aware that this was public knowledge (hence had to keep confidence).

          Note in Giles’ article (above) that it was updated with more details…

          Paul

  2. Nick 4 years ago

    So what you’re saying is a dispatchable grid can easily be redispatched. Thank you, that’s very helpful.

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