Or just overbuild your generation sources?

How is overbuilding going to help when the source of the power itself is intermittent? The sun regularly sets and the wind has this unfortunate habit of not blowing. Or, oddly enough, blowing too much.

If we hope to go 100% renewable, storage is a key piece of that puzzle.

Nuclear also has this problem because it cannot be easily tuned down during low demand periods.

Much of the pumped hydro that exists today was built to handle excess nuclear.

Nuclear's electrical output can indeed be turned down, by over-cooling the steam in the turbines. The reactor is putting out the same power, but less electricity is generated since you're deliberately increasing waste heat. This is not efficient so it's rarely done.

Furthermore, too much energy is a far easier problem to solve than too little energy. People can desalinate water, or do any other energy intensive things.

Technically yes if you have an entire fleet to both spread the load following across and their manage their fuel cycles since they get less flexible the further into a fuel cycle a reactor is.

Economically? Load following with nuclear power means an even worse business case than running at 100% 24/7. And nuclear power is already a laughably bad business case when running at 100%.

The fuel is burned at the same rate using this method of modulating output. Thermal output from the reactor is the same. Electrical output is reduced because heat is deliberately wasted.

Nuclear can handle variable loads just fine, if reactors are designed with load-following in mind. France does that, for example.

Technically yes if you have an entire fleet to both spread the load following across and their manage their fuel cycles since they get less flexible the further into a fuel cycle a reactor is.

Economically? Load following with nuclear power means an even worse business case than running at 100% 24/7. And nuclear power is already a laughably bad business case when running at 100%.

You don't need to change fuel cycles to reduce the output of a nuclear plant. You can accomplish it by more aggressively cooling the water in the steam turbines, effectively wasting heat (and thus generating less power).

Nuclear is a bad business case compared to a fossil fuel grid. Solar and wind backed by fossil fuels are a better business choice, too. But when it comes to a fossil-fuel free grid, it's the only viable option if you don't have a big source of hydropower nearby. Batteries can't deliver the required storage capacity. Remember, the world uses 60,000 GWh of electricity per day. And as transportation and industrial uses of fossil fuels are electrified, that'll increase.

Batteries and hydro are not the only storage options.

What are the other storage options? Besides batteries and hydroelectric, there's only prototype technologies that haven't seen any significant deployment at scale. Compressed air, hydrogen, and power to gas have been tried but no at anywhere near grid scales.

Five years ago batteries weren’t anywhere near grid scale either. Arguably they still aren’t. That doesn’t mean we should not consider them when talking snot the grid in 2040.

Sure. But we also shouldn't assume they will be successful at grid-scale either. Planning a grid assuming that some future storage technology will be a silver bullet that solves grid storage is a massive gamble.

Hydroelectric storage is the only grid-scale energy storage system available to us, and it's geographically dependent. And the places that are suitable for hydroelectric storage usually don't need it because they can just generate electricity via hydropower anyway. Until your hypothetical breakthrough in power-to-gas or giant flywheels actually happens, this is the state of grid storage.

It's not such a massive gamble if you can just keep relying on natural gas peaker plants in case storage is somehow unsolvable, which seems quite unlikely given that we have a dozen completely different technologies for storage in the pipeline.

Notably it also runs the reactors much harder, which has led to situations like France needing to shut all nuclear plants at once for maintenance.

“Oh no we have too much power, what are we going to do with it” is a much better problem to have than “the sun and wind are going down at the same time and we don’t have enough power, what are we going to do about it”.

It means the nuclear power plants shut down and then start losing money hand over fist, eventually closing.

Don’t piss on my leg and tell me it’s raining. Most of the costs and all of the shutdowns in nuclear power are primarily motivated by anti-nuclear activism. What you’re describing is a policy choice, not an essential reality.

If it costs you money to generate power at a time you cannot sell it, that is losing money. Wind and solar are unique in that they have low marginal costs, whereas a nuclear plant requires more staffing and fuel burn.

I don't understand why you're coming about this problem from a "100% nuclear" situation. That's not the case for the world, and likely never will be the case. But heck, let's assume all you've got to work with is nuclear.

You have a baseload. That's basically the minimum load that always exists. You don't have to worry about selling the power, it's already sold. And then you have peak. Both of these are time / weather dependent but we're still quite able to plan days, if not weeks and months, in advance for what those two values will be. As an example, let's get back to the original topic of the article.

If you're Google and you have a particular datacenter at a location, you know what that baseload is. You know what the peak is. It's a pretty simple calculation to figure out what is most cost-effective here. It's probably even easier for you than the local power company, as base and peak loads likely don't fluctuate much for you outside of HVAC keeping up with weather. It might be to use nuclear for just base load and use the local grid for the rest. It might be to over-produce occasionally because that's still cheaper than buying from the local system operator. Hell, you can probably sell any access, but that's more of a problem than most people think.

But the point is nuclear is king when it comes to baseload power supply. And a datacenter, which consumes a lot of power consistently, is almost entirely baseload.

Also, if you're serious about the problem of "our nuclear power plants are producing more power than we need and we can't turn them off because then we'll have a power shortage", there are applications to dump "bonus" energy into. You'd run into the same problem with renewables too; the difference is that with nuclear, you can avoid the "not enough energy" problem.

If you're not in Texas, there's such a thing as paying to keep capacity available, and then you don't lose money.

And power plants having individual finances in the first place is a policy choice, not a law of nature.

We have a version of that in Texas, too. There are some commercial cryptocurrency mining operations that pay for a certain level of power capacity, and if the grid is running low on power, the grid just buys the capacity back from them and they stop mining for awhile.

If you find cryptocurrency mining objectionable for some reason, you could apply the same basic principle to things like aluminum refining or desalination.

That's still only paying when the capacity is needed. It doesn't do a good job of incentivizing power sources/releases that are needed very rarely.

It wont help much but it was the actul solution when the main source of electricity was fossil fuels because you could stockpile the fossil fuel

Simulation studies have covered this. It addresses it by providing more power when there is less sunlight and less wind.

Overbuilding doesn't make solar generate power at night. Days with minimal wind can see 10% average wind speeds or less.

>Graham says that the CSIRO modelling showed that at very high levels of wind and solar, a maximum of half a day’s average demand was needed for storage. In some areas of the grid, only around three hours might be needed.

https://reneweconomy.com.au/much-storage-needed-solar-wind-p...

Sadly, there's far, far, far too much FUD floating around about storage (understandably, coz wind+solar threatens the nuclear+carbon lobbies), and not enough thorough and realistic studies like this one.

I've heard people say "oh you cant pay attention to this study because it's in Australia which must be discounted because [reasons], what about [ other country ]?", and I'd welcome seeing an alternative study making appropriate assumptions, but none of these comments so far come attached to anything other than FUD.

I've also seen far, far too many people build or cite a "naive" models that make inappropriate assumptions (e.g. that zero power is generated at night by wind).

> I've heard people say "oh you cant pay attention to this study because it's in Australia

So a study for Australia should be applicable everywhere else? Like in Germany or Norway?

Norway is already 100% renewable because it has lots of hydropower. Germany on the other hand, would suffer from an extremely unreliable grid even with 50% overproduction and 12 hours of storage. The further a region is from the equator, the more variability in the production of wind and solar. This study models how reliable grids would be with wind, solar, and storage: https://www.nature.com/articles/s41467-021-26355-z

The issue is that electrical grids have very high reliability requirements (upwards of 99.95%). Plenty of models claiming that small amounts of storage required neglect to mention how frequently they will encounter insufficient generation. Remember, even fulfilling demand 99% of the time is a 20x increase in blackouts.

Also, even just 12 hours of storage globally would be 30,000 GWh of storage. That's still about 50 times the amount of batteries produced annually. The reality is that hydropower is the only feasible form of grid storage.

More applicable than FUD.

I am, as I said, still waiting for models which demonstrate that it is wildly different...

I actually worked on such a model professionally (as in "being paid for it") in 2006, for Germany.

Here's a good overview article: https://energytransition.org/2017/07/germanys-worse-case-sce...

> Germany will always need dispatchability roughly at the level of its annual peak demand

The solution they're proposing is power-to-gas. Which so far has been way too expensive to matter.

P2G isn't actually horrendously expensive compared to nuclear power, it's just horrendously expensive to regular old natural gas.

Power to gas for the "worst case scenarios" would also be the last thing you'd do to transition a grid from 97% carbon free to 100% carbon free.

The further a region is to the poles, the worse intermittency becomes. Both for solar and for wind: https://www.nature.com/articles/s41467-021-26355-z

> However, the share of solar generation increases less, or even decreases, in higher-latitude countries like Russia, Canada, and Germany (Fig. 2b). These trends continue as more storage is added, so that with 12 h of energy storage and no excess annual generation, 83–94% (average 90%) of electricity demand is met with mixes of 10–70% solar power (49% on average; Fig. 2c).

Even with 12 hours of storage, Germany would be seeing blackouts weekly.

To put this in perspective:

> reliability standards in industrialized countries are typically very high (e.g., targeting <2–3 h of unplanned outages per year, or ~99.97%). Resource adequacy planning standards for “1-in-10” are also high: in North America (BAL-502-RF-03), generating resources must be adequate to provide no more than 1 day of unmet electricity demand—or in some cases 1 loss of load event—in 10 years (i.e., 99.97% or 99.99%, respectively)

So no, even with 12 hours of storage and 50% overcapacity, we'd have an unacceptably unreliable grid.

Also, your linked article is not modelling a carbon-free grid:

> Graham says that the CSIRO modelling showed that at very high levels of wind and solar, a maximum of half a day’s average demand was needed for storage. In some areas of the grid, only around three hours might be needed.

What are these "very high levels of wind and solar"? How much of the remaining demand is satisfied by fossil fuels? The article doesn't say.

50% overcapacity of renewables is still spending way, way less than the equivalent for nuclear. How do the numbers look with 100% or 200% overcapacity, where you're still spending about half of what you would spend on nuclear?

Adding more overcapacity just wastes energy. Storage is the main bottleneck to widespread renewable adoption without frequent blackouts. Having more energy when you don't need it is only really useful if you can store that energy.

No, it also makes the probability of supply not meeting demand lower. Overcapacity tends to feature in most analysis of a fully renewable grid because of that and because it's currently cheaper than storage for all but very short timescales.