Energy market data pulled with AI exposes Snowy Hydro bidding

Aidan Morrison@FootnotesGuy

I think this is evidence of our government-owned energy generator, Snowy Hydro, unethically gouging consumers. It might be legal. Maybe. But I think it's wrong. Electricity consumers and taxpayers should be furious.

I pulled this data with the help of AI. This would be days or weeks of work a few years ago. Now getting all the data in the ideal format to understand takes just minutes. Much harder is figuring out what it actually means.

I should hasten to say, I'm pro-market enough to hate it when people rail against 'price-gouging'. Provided the market isn't rigged, there's nothing wrong with sellers charging what they can. Prices are important signals. If the market's functioning properly, it will bring in new supply from competitors, and/or allocate limited supplies to those with greatest need.

But in this case, I think the actions taken by Snowy Hydro show absolutely masterful exploitation of failures in our energy market, in particular transmission constraints and poor system design, which competitors have no means of correcting through new supply. Because the supply is fixed by a badly designed transmission build-out, competition is held away.

The damning thing here is the change in the ramp-down rates. That's what makes the whole thing go from smart, and brutally self-interested manipulation of the market, to something that seems to me to be dishonest. That, set in the context of the counterprice flows, and the market intervention by @AEMO_Energy to impose constraints that would affect other competitors ability to provide power in the market.

You see, the first thing you'd think of for re-bidding behaviour that's potentially profit-maximising, and hurting consumers, is raising your bids to higher prices, when you know that there's a shortage.

That's child's play compared to what's going on here.

At rebid 6, Snowy drops their bid down to negative values for half their capacity. (See green block start on bottom panel) Ie, "I'll pay people to take away my power". Surely lower bids helps lower prices right?

Usually right, but here it's wrong. And this is where Snowy Hydro's market team shows they're true ninjas. They know that there's a bottle-neck so a bunch of power in Southern NSW can't reach Sydney, and push down prices at the reference point. So they bid super-low. Negative $1000. The minimum. That guarantees they get dispatched. The plebs in the wind-farms trying to get every MW they can out at a positive price would never take that kind of risk. So they bid negative, massively, to ensure that their power is flowing to market ahead of any other generator in Southern NSW.

But that's only the opening move, and Snowy Hydro are thinking many steps ahead already.

They would know the network well enough to know that turning their own pumps on in this part of the network will force power over the border into Victoria against price signals. Victoria has negative prices, NSW positive, at 13:40. Prior to this point, before Tumut 3 turns on, a bit of power is flowing from Vic to NSW, which is helpful. Their negative prices helps bid down NSW's positive prices. Which is good. Until...

Tumut 3 turns on nearly 900MW in far-South NSW with their crazy-low bid. Then power starts flowing the wrong way, from positive prices to negative, over the Vic border. Promising generators they'd get paid to generate, then promising Victorian consumers they'd get paid to consumer NSW's excess.

This "negative residue" starts to build up slowly at first. But as prices rise in NSW, as the afternoon heat builds, it speeds up a little. Then comes Snowy Hydro's next big move. Rebid 7 in the table. They push their entire 1.78GW generation capacity down to the floor price, so it gets dispatched. And this pushes a mass of electricity across the border at a pretty big counter-price delta.

Snowy Hydro knows perfectly well what this does. It pushes the cumulative residues over a level where AEMO has a policy to intervene, imposing a constraint on the market to stop these negative residues building up too high, racking up bills for high priced generation in one state that no-one in the other state where the power landed agreed to pay for. Effectively the idea is to 'clamp' the interconnector to stop power flowing the wrong way across it. But you can't actually stop electrons by clamping the interconnector. You have to adjust the pushes and pulls of generators and loads to prevent the electric fields pushing power the wrong way. That means directing generators to switch off.

And here's the real cunning in Snowy Hydro's plan. Because they had so obviously caused the mayhem by pushing nearly 2GW into the grid in a place where the power flowed over the border away from where it was really needed, surely AEMO's new constraints to prevent that flow would switch that generator (Tumut 3) straight back off? It was dispatching nothing an hour earlier. Surely they get switched off?

Anticipating this, right back at rebid 6 Snowy had adjusted their ramp-down rates registered with the market operator. This is the step which crosses a line in my mind. Because I strongly suspect that nothing at all changed in the technical capability of Tumut 3 that meant that it couldn't be ramped down as fast as they had told the market they could do minutes before, and would tell the market they could do again just a few hours later. The reasons given mention nothing about technical problems. So this is done as a market move. They know this can make them money, but the truth is that their machinery could ramp at the same (high) rate throughout this episode, I assume.

But by lowering their ramp rate down so far, to just 18MW/minute, they effectively meant that AEMO couldn't turn them off. They can only be gradually ramped down. They should've been the first ones turned off to prevent the counterprice flows, but they'd manipulated their ramp so that they couldn't be switched off.

Consequently, all the other generators in Southern NSW got switched off in preference. And this drove prices sky-high, because Sydney needed energy. Prices reached over $20,000/MW in a couple of increments soon after.

And, apparently, because the most badly positioned generator (Tumut 3) that was pumping out energy near the Victorian border couldn't be ramped down quickly, enormous 'negative residues' accrued, with a couple million in the 5 mins after AEMO notified the market of the constraint to (attempt to) limit the counterprice flows. And, more than a million ten minutes later.

These 'residues' just get lumped onto network charges, and end up being paid by consumers. So it's pretty clear that Snowy Hydro's re-bid limiting the ramp rate caused those additional negative residues to arrive, hurting consumers directly.

But also very likely, though there are few more moving parts involved and hence just slightly harder to say with certainty, the bidding behaviour here, which triggered the market intervention to clamp the interconnector to Victoria, almost certainly contributed to the price volatility reaching such extreme peaks in NSW. That would be a much, much more significant cost to consumers, I've seen estimates from @EnergyWrapAU putting Snowy's windfall at around $15 million in one hot hour.

So this I think crosses a line for me. Because the changed ramp-down rate is almost certainly made-up, reflecting nothing in their machinery at all, and because they knowingly caused bad outcomes for consumers on the way to getting paid that otherwise wouldn't have occurred (the counter-price flows for sure, and the price spike almost certainly) I don't think it's ethical behaviour for any generator, and certainly not one owned by taxpayers.

I strongly suspect that if Snowy Hydro had left Tumut 3 with their bids as they were at 13:30, that the counterprice flows would have been far more moderate, possibly not triggering an intervention. And also NSW wind generators a little closer to Sydney would have done a better job meeting rising demand, and prices might have risen a bit, but to nothing like the extend that they actually did when they were forcibly switched off while Snowy Hydro was running Tumut 3 which was sending power the wrong way over the border into Victoria. Because they couldn't be switched off because of the manipulated ramp-rates.