Comment by alexey-salmin | Hacker News Reader

Comment by alexey-salmin | Hacker News Reader

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> The issue with outdated grids is that it relies on technology (spinning mass) that's at this point a century old. Which makes it brittle against outages like you describe. The solution is not more spinning mass but batteries and renewables to take the place of that spinning mass. A battery can respond to oscillations in milliseconds. If you then add flexible load that can spin up/down based on the amount of available power, you gain a lot of stability.

Why the spinning mass technology being "century old" (more like "millennia old" but anyways) is a problem somehow? The Newton's First Law didn't change much in the time that has passed.

Anyone who tried to "respond to oscillations in milliseconds" knows how hard that problem is because the force you apply is integrated twice before it takes effect. Try stabilizing a swing by pushing it's forward when it's behind the equilibrium point and pushing it backward when it's ahead of it. Now imagine a grid of swings connected by rubber bands and a distributed system of independent actors responding to oscillations. There are much more ways in which this system can diverge rather then converge.

Time may prove me wrong, but the arguments like "spinning mass is old therefore should be replaced" certainly won't.

> Newton's First Law didn't change much in the time that has passed.

No, but technology has moved on quite a bit. Heavy fly wheels are no longer the state of the art here.

A few tens of GW of battery capacity (i.e. a few dozen nuclear plants worth of capacity) that can switch on/off in milliseconds can do a lot for grid stability. That's part of the reason why grid operators are rolling out so much batteries. It's not necessarily about supplying energy for a very long time but about smoothing out peaks and dips in energy supply and demand and responding more or less in real time to that.

This stuff is basically being rolled out at industrial scale in a lot of places. Australia, China, etc. pretty much run increasingly on mostly renewables. This is no longer as speculative as it would have been ten years ago.

Yes, there are engineering challenges with rolling that stuff out in a lot of places. And even more policy and regulation challenges. Actually that is, by far, the #1 challenge in places like the US and Europe. Grid operators are simply structured and incentivized wrong to deal with this stuff efficiently. Texas is actually not doing too bad relative to e.g. California. But they clearly have some challenges still.

> A few tens of GW of battery capacity (i.e. a few dozen nuclear plants worth of capacity) that can switch on/off in milliseconds can do a lot for grid stability.

I think this is a misunderstanding of the problem.

Now, don't get me wrong, I believe flywheels are no longer involved but at one point they were for batteries and solar. Not to store energy, but rather to form the output voltage and to give the correct "inertia" of the waveform to maintain a correct phase with the grid. Prior, both batteries and solar were frequency followers. They'd look at the previous peaks and valleys to determine what their output voltage (or resistance) should be. If the input voltage fell too far, both solar and batteries would cut off to avoid damaging equipment on the grid. This is part of why the winter storm killed the texas grid (to my understanding) the voltage dipped too low which ultimately caused renewables to shut off completely to avoid damaging the grid. That all was somewhat of a cascading disaster.

Flywheels have been used as an inertia source to allow for both solar and batteries to act more like a hydro or fossil fuel generator. That's the grid forming technology. I believe (can someone verify?) that there are now all digital versions of this. But it's delicate software. Getting it wrong can do really bad things like destroying other generators or breaking expensive fuses.

I would imagine that any single renewable plant could handle that - the the frequency drifts out of sync, it's only the inverter that will blow up.

It's an expensive part to be sure, but not so expensive that a plant couldn't keep a few spares.

Respectfully, I believe you have confused "new" with "state of the art". China is likely using batteries because their battery production is subsidized, Australia's trading partner is China so basically equivalent.

Perhaps a bad analogy, but it seems these battery systems attempt to stabilize by "pushing", whereas spinning mass can also work through "dragging" the phase. So eventually, you will have just a few rotating masses setting the freq and phase, with more and more systems tracking that and pushing, which seems like a recipe for chaotic equilibrium.

> Respectfully, I believe you have confused "new" with "state of the art". China is likely using batteries because their battery production is subsidized, Australia's trading partner is China so basically equivalent.

This is comically wrong. You're just making things up. Australia is at the forefront of this new tech due to necessity and some good luck. Scroll to the bottom of this article and have a look at the graph. It shows Australia has 5 times the grid forming battery infrastructure deployed or under construction than China or the US, or pretty much any other country. It is very much SOTA, needed for a grid that is a rapidly changing mix of rooftop solar, hydro, coal, gas and wind spread over a country the size of the continental US. Rotating masses are not going to cut it.

https://arena.gov.au/blog/australias-grid-forming-battery-re...

No, they are doing that because they have a ten year head start on the rest of the world. The US & EU not having done their homework is entirely on them. The US is choosing to pump a lot of funding into fossil fuels instead. You could say that China is simply spending smarter.

The rest is just economics. We might suck at making batteries. But we suck even more at making new gas/coal plants or fueling those cost effectively.

Anyway, this stuff is being deployed by the hundreds of gwh per year now. Much of it in China but some non trivial amounts in places like Texas and California as well. As a result, the grid is actually getting more stable, not less stable.

> nuclear plants worth of capacity) that can switch on/off in milliseconds

Nuclear has this little problem getting in the way of switching on/off quickly:

https://en.wikipedia.org/wiki/Xenon-135

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