[Manuel_D]

> It can regenerate any water it needs to expel in such a situation in a few weeks using Tumut 2's regular output.

But it regenerates this very slowly. It'd take over a month to recharge. Again, you can't compare a pumped storage reservoir with a precipitation-based reservoir (aka a dam). With the former you put energy in and energy is stored. With the latter you just have to wait for the rains to fall. This is not useful for cyclical, or as you insist we word it, diurnal storage. Anyone with a solid grasp of logic can see that, too.

> Also there is plenty of precedent for something called a battery where using the full nameplate capacity has a high cost and is not easily reversible. It's called a lead acid battery and was one of the most common chemistries for the better part of a century

Lead acid batteries only last ~300 cycles so you'd have to replace them every year if used for cyclical storage. This is why lithium based battery chemistries are used.

[Schroedingersat]

> But it regenerates this very slowly. It'd take over a month to recharge. Again, you can't compare a pumped storage reservoir with a precipitation-based reservoir (aka a dam). With the former you put energy in and energy is stored. With the latter you just have to wait for the rains to fall. This is not useful for cyclical, or as you insist we word it, diurnal storage. Anyone with a solid grasp of logic can see that, too.

The refill comes from tumut 2. And again, it's a 2GW storage that provides diurnal, five day, and seasonal. Do try to comprehend basic concepts like 'water that goes through a dam goes to the lower reservoir'.

> Lead acid batteries only last ~300 cycles so you'd have to replace them every year if used for cyclical storage. This is why lithium based battery chemistries are used.

This doesn't matter. It's called a battery and you can't typically use nameplate capacity. It's exactly the thing you keep acting outraged about. It's also probably the thing most associated with the word battery other than single use cells.

[Manuel_D]

> The refill comes from tumut 2. And again, it's a 2GW storage that provides diurnal, five day, and seasonal. Do try to comprehend basic concepts like 'water that goes through a dam goes to the lower reservoir'

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.

> This doesn't matter. It's called a battery and you can't typically use nameplate capacity. It's exactly the thing you keep acting outraged about. It's also probably the thing most associated with the word battery other than single use cells.

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.

[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