[londons_explore]

> nor are brief periods of multi-gigawatt draw/dumping as needed.

Actually this is typically an issue for grid batteries.

Spinning generators can easily briefly go to 10x the rated current for a second or so to smooth out big anomalies.

Stationary batteries inverters can't do 10x current spikes ever - the max they can get to is more like 1.2x for a few seconds.

That means you end up needing a lot of batteries to provide the same spinning reserve as one regular power station.

[AnotherGoodName]

Collectively Australia's battery storage systems will be able to beat any single power plant for peak output in Australia once fully built out based on pure numbers. But for these sorts of grid oscillations the more important thing is the localization of generation. Which obviously favours the batteries over large centralized power stations in any case.

[adev_]

Being enthusiastic about battery technologies is one thing, spreading misinformation to support someone convictions is an other.

What causes the Iberian blackout is excessive reactive power and a lack of compensation at a given time (due to multiple factors).

Compensation of reactive power has strictly nothing to do with localization of generation. It barely even can be assimilated to oscillations

That's complete garbage and it shows mainly you do not seem to know much about Electricity power in general.

[ajross]

That... doesn't sound correct. Inverters are the cheap part, you can literally wire as many as you want in parallel. Batteries have immense power availability, with most chemistries you can trivially deliver the entire capacity in half an hour or so (more like 5 minutes with lithium cells).

Basically I'm dubious. I'm sure there are grids somewhere that have misprovisioned their inverter capacity, but I don't buy that battery facilities are inherently unable to buffer spikes. Is there a cite I can read?

[AnotherGoodName]

Agreed. The relatively small battery substation linked above can output 2GW of equivalent inertia generation (a measure to align batteries to inertial power systems) when needed. That's an entire power station they can match for short periods of time. Link: https://www.energymagazine.com.au/sa-approves-world-first-ba...

Australia's largest power plant has 2.9GW of inertial generation assuming all generators are running at 100%. As in the small battery substation alone comes close to the countries largest power station. I'm not sure where the idea that lithium ion can't dump power quickly comes from. They are absolutely phenomenal at it. Australia's building dozens of these substations too since they are so cheap and reduce overall power costs. It's a win from all points of view.

[bob1029]

The article does not describe an inertia constant. Without the time component, any comparison to traditional systems is meaningless. Inertia is a measure of energy, not power.

Large spinning masses can provide several seconds of inertia. For 2GW of traditional turbine, you would have between 10-20 gigawatt-seconds of energy that is instantly available at any moment to resist RoCoF.

[ajross]

The switching rate of a good power MOSFET has a bandwidth in megahertz. It's... all solid state electronics. Again, this is just wrong, absent someone showing a cite. It's very weird seeing this kind of seeming ignorance of basic electrical engineering on a hacker site of all places.

[tacticus]

> assuming all generators are running at 100%.

which they won't ever be given the habits of coal plants to suffer outages whenever it's convenient to pump the price up.

[bob1029]

> Inverters are the cheap part

The whole point with actual inertia is that you get a large multiple of your maximum capacity without any redundant parts or added system complexity.

Keeping around 10x+ more semiconductors than you need to cover a tiny fraction of operational scenarios is difficult economics.

A semiconductor device cannot be overloaded like a spinning generator or transmission infrastructure can. You cannot trade temperature and maintenance schedule for capacity in the same way. Semiconductors have far more brittle operating parameters.

[ajross]

> Keeping around 10x+ more semiconductors than you need to cover a tiny fraction of operational scenarios is difficult economics.

Not according to the prices I see. Digikey tells me I can switch a MW of power for about the price of a MBP. I ask again, is there a citation for this nonsense?

[eldaisfish]

it is technically correct, but so are you.

More inverters in parallel will achieve the same end goal - fast frequency response.

[ajross]

Are you actually certain there are insufficient inverters though? Again, that doesn't pass the smell test and I'd want to see a cite for "batteries don't work for high frequency spike buffering because of inverter shortfalls" or something.

[eldaisfish]

i'm certain there are more than enough inverters.

what's correct is that each individual inverter can only increase its power output momentarily to 20% or so above its maximum. Add more inverters and that problem is solved.

[probablypower]

You can google "system inertia" as a starting point.

[epistasis]

When it comes to the grid, there's a lot of outdated information left over from the 20th century, so any web search for "system interia" needs to also include some searches on "grid forming inverter"' to make sure that the info is complete.

(And "reactive power" could be good too but not absolutely necessary to understand at first...

[ajross]

I understand the concept. I was asking for a cite about the seemingly-incorrect point about batteries. FWIW, that very search term doesn't produce the string "battery" anywhere on the first page.

[rcxdude]

This is what batteries can provide very well.

[z_rex]

A spinning generator is not outputting 10x it's rated current over any significant amount of time. You can only add so much steam or fuel to a turbine, and the rotor has a lot of inertia, but not enough to account for 10X its rated capacity for a second. The electrical switchyards would trip nearly instantaneously if it's connected plant output 10X its rated input.

[cyberax]

A properly running grid with spinning generators never needs the 10x rated current. More importantly, oscillations are dampened by the rotating masses.

[zekrioca]

Let alone the transmission lines totally catching fire after a 10X output increase.

[Gud]

Where are you getting this information from?

Although I’m hardly an expert on power lines(my factory produces HV switchgear), a 1s short circuit current rating of 10x(actually more) is normal, standard to IEC norms.

[zekrioca]

Arcing.

[scotty79]

I think they meant 10x current not 10x voltage, so no arcing.

[egberts1]

You can if the load was 10x under max. before getting tripped.

Misaligned oscillation can occurs under ANY load.

[javawizard]

Batteries would also be able to 10x if their load was 10x under max, so I'm not sure how this is relevant to GP's point.

[lobochrome]

The inverter would melt presumably.

[Geezus_42]

Just looking for an excuse. Lol

[pjc50]

> Spinning generators can easily briefly go to 10x the rated current for a second or so to smooth out big anomalies.

I'm very suspicious of this, because it would also imply 10x overcurrent on the associated transmission gear. There's limits on how much you can overcurrent a transformer before the core magnetically saturates, for example. Also I would expect protection systems to trip out at such a huge divergence from rated current. Do we have a citation?

[outside1234]

What batteries CAN do however is go from 0W to their capacity watts in milliseconds. It is their instant-on ability that is disruptive.

[IndrekR]

Not only from 0W, but from negative capacity (max charging power) to positive capacity (max discharging power).

[giantg2]

Seems like pumped hydro offers a nice compromise.

[AnotherGoodName]

Fwiw the hornsdale battery linked above cost AUD$172 million and can provide 2000MW of equivalent inertia. Link: https://www.energymagazine.com.au/sa-approves-world-first-ba...

That equivalent inertia can only be done for short periods but that's exactly what grids need in stability - there's generally no lack of total generation, just a need to jump in and smooth out spikes.

You can't build a dam for that price, nor could you do it in under 100 days from contract signing as that battery was built. Batteries are definitely the answer here. The 'more spinning mass' answers don't make sense since Australia literally solved the above problem in a much cheaper way already.

[giantg2]

You don't need to build a dam, you just need the pipes and pumps for an existing dam (or elevated natural basin).

[_carbyau_]

I thought you needed two dams. One higher than the other. You pump water back and forth between the two to generate or capture energy.

Is it that common that dams are already existing in nearby-ish pairs with the sufficient height difference? And that we haven't done this already?

Doing this is good where we can. But it has geographical limitations. Batteries don't so much.

[Rodeoclash]

My layman's understanding is that most locations that are suitable for pumped storage already have pumped storage built on them.

[MobiusHorizons]

Yep, this is the issue. That and land cost. Also pumped hydro is most useful when you need very large capacity storage, whereas for preventing blackouts you need very high capacity fast generating to fix oscillations or to allow more generating capacity to come on line. They are basically acting as decoupling capacitors (except for AC) in this application.

[Polizeiposaune]

You need two sufficiently large bodies of water close to each other at different elevations. You don't necessarily need two dams - for instance, the Ludington pumped storage plant adjacent to Lake Michigan uses the lake as the lower body.

[floatrock]

Most economically-suitable locations for pumped hydro have been built out already.

You can always use a ton more concrete and force new locations, but the best locations have already been utilized and scaling law of batteries has brought them to the point where they're more competitive than new hydro for this kind of use.

[bryanlarsen]

Most economical locations for hydro generation have been built out already. Pumped hydro doesn't require flow like generation does, so there are thousands of times more suitable locations. Those haven't been built out.

[Maxion]

At least in my country they have. They keep trying to build a facility but anything they come up with, the ROI just isn't there.

[bryanlarsen]

In other words, there are lots of places they could build, but it's just too expensive to build and/or the value of long term electricity storage is too low.

[plorg]

Sure, if you can site it.