[Schroedingersat]

> If you're not running them at full depth of discharge then you're cutting down your usable storage capacity. If you're running 1 GWh of batteries but you're only going to 50% depth of discharge to extend longevity then you've really only provisioned 500 MWh of storage.

But they're sold and advertised based on the emount of energy they can dispense when full. Once you use that much energy you can never store that much again. And everyone is fine with this. Snowy 2 is less limited than this.

> And for the fourth time, this water is from precipitation. You can't supply electricity to it and pump more water. It's not storage in the sense that you can supply it with a GWh of electricity and later tap the energy you put into it. You're literally saying every single dam is a "pumped storage" facility even if there's no way to pump water into the upper reservoir. Do try to comprehend the difference between pumped storage and a dam.

Every single dam is storage. It's why so many were built in the nuclear boom. The 40GWh can be cycled any time, the 240GW can be cycled at any point it is needed in any real scenario (ie. When water levels are not at max and tumut 3 is also using its storage in the same direction). The rest is recharged by curtailing normal hydroelectric flow later (by putting renewable energy into the grid) on seasonal timescales. The system needs to dispense a certain amount of water anyway so the full 350 is available cosistently on a seasonal basis. You may have a point if you were asserting calling it 350 rather than 240 was a bit misleading without further context and caveats (ie. Only once or twice a year and only for that 'week long renewable drought' so beloved of stans of generation technologies that go offline for weeks unexpectedly like coal), but you weren't. Instead you were yelling that it was 40.

Ergo bad faith.

[Manuel_D]

> But they're sold and advertised based on the emount [sic] of energy they can dispense when full.

Right, but renewables need storage that we can charge and discharge daily, not seasonal storage. We're back to the 10 KWh battery that can only be charged to 3 kwh on demand.

> Every single dam is storage. It's why so many were built in the nuclear boom.

Renewable growth predated the nuclear boom by a long margin: concrete and effective turbines made possible bid advances in hydropower around the 1930s and 1940s. This is when the Hoover dam, the Coulee dam, and most of the other big hydro power plants were built. The nuclear boom was in the 1960s and 70s.

> The 40GWh can be cycled any time

And again, this is the main form of storage we need to flatten out the duck curve.

> the 240GW can be cycled at any point it is needed

Yes, but then it takes a long time to refill. This is useful for seasonal storage, as you point out, but again flattening the daily fluctuation is what's really necessary. The bigger value is for the use case that's not in as much demand.

The point of storage is that you can capture the surplus energy of renewables. The idea is that if my grid consumes 100 GW of electricity and I produce 150 GW during the day I can capture that extra 50 GW. Dams can't do this. Yes, you can reduce a dam's production when renewables are at peak generation and let water levels rise. But that's not really storage. What happens when the renewables produce so much energy that it's saturating demand? You can't capture that surplus energy with just a dam, you need a bidirectional connection.

Pointing out that you're sidestepping the fact that only a much smaller portion of storage capacity can by cycled daily like a lithium battery is not at all bad faith.

[Schroedingersat]

> Right, but renewables need storage that we can charge and discharge daily, not seasonal storage

...which it can do for the full 2GW rated power without discharging water.

Every time load shifting or diurnal storage is mentioned, there are cries of 'but what abuurt the 3 day energy drought you need four days'

Now when presented with a system that is designed precisely for this use case you start whining.

Make up your mind.

> What happens when the renewables produce so much energy that it's saturating demand? You can't capture that surplus energy with just a dam, you need a bidirectional connection.

In addition to this you can use Tumut 2 as your output, then when there is surplus energy store it via snowy 2. This will take a few weeks, but it is a way to fill the entire 350GWh with curtailed renewable energy if that is what you really want. Some water is lost in a full emptying or when changing from diurnal capability to 5 day capability, but some water must go downstream anyway or blowering cannot work. The full 7 days can be cycled a few times a year, which is what it was built for.

Even without that, you've absorbed 2GW with your hydro curtailment and your 2GW storage facility is storing 2GW for a week exactly as advertised. Focusing on a technicality that doesn't come up is bad faith. You can't cycle 350GWh with 2GW in a day. Can you not divide?

[Manuel_D]

> Every time load shifting or diurnal storage is mentioned, there are cries of 'but what abuurt the 3 day energy drought you need four days' Now when presented with a system that is designed precisely for this use case you start whining. Make up your mind.

You were the first one to bring up seasonal storage here [1]. Nobody was ever talking about seasonal storage until you brought it up. "but what abuurt the 3 day energy drought you need four days" this is all you talking, bud.

> In addition to this you can use Tumut 2 as your output, then when there is surplus energy store it via snowy 2. This will take a few weeks, but it is a way to fill the entire 350GWh with curtailed renewable energy if that is what you really want.

But it's not what we really want. What we really want is to capture the excess production of intermittent sources. Saying a dam is energy storage is like saying natural gas plants are energy storage. You can curtail their output when renewables are in production, sure: If you have 100 GW of demand and 50 GW of solar production during the day you can run your natural gas plants at 50 GW during the day and 100 GW at night. But what happens when solar grows to 200 GW? The objective is to use 100 GW and store 100 GW during the day and tap into the stored energy at night. Dams and natural gas don't let you do that.

1. https://news.ycombinator.com/item?id=33648855

[Schroedingersat]

> Nobody was ever talking about seasonal storage until you brought it up

It says 2000MW on the document you linked. It's not anyone else's fault if you can't be bothered comparing the numbers 2, 24 and 350.

> But it's not what we really want. What we really want is to capture the excess production of intermittent sources.

Think it through for even half a second. If Tumut 2 is operating at average, then the water it ejects over the course of days or weeks can be stored at any rate up to and including 2GW. In all practical scenarios (which do not include a week straight with nothing but draw followed by a week straight of nothing but charging) what you describe is exactly what snowy 2 does. In situations where the entire system doesn't need to produce net energy, diurnal draw cycles can feed water into Talbingo, and diurnal charge cycles can feed that water into Tantangara (and tantangara s higher so it can be a small jet energy draw). The water needs to be released anyway (but not in any particular week) for irrigation and to keep the river healthy so where is the problem?

If you lack the imagination or ability to apply logic necessary to see how three parts can fit together that's not on anyone else for not spoon feeding you the obvious conclusions available from the sources you cited.