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Comment by samus | Hacker News Reader

It is probably smart to keep around a certain capacity of nonrenewables to provide at least some base load. Long periods of low sunshine and slow winds could deplete batteries to a critical level. Also, the turbines of big powerplants act as grid frequency stabilizer. Do grid-scale batteries use alternators or might they run flywheels?

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One of the biggest challenges with renewable energy in energy grids is something called inertia.

Her's a nice article:

https://www.fingridlehti.fi/en/what-is-inertia/

Batteries can and are used for frequency stabilization, yes.

https://www.pv-magazine.com/2022/07/27/tesla-big-battery-beg...

Superconducting coils as well. Those are popular near windfarms due to their fast response time, both on the uptake as the release.

Inverters have come a long way in the past few years. They are at the point where they are (subjectively) better than giant flywheels.

I believe they just switch on and off fast enough.

Tesla power wall does that.

Yes, but the rest of the grid can not, except for some forms of hydro, flywheels, superconducting coils and grid scale batteries. They hydro has a fastest rate of change of about 1 minute from zero to full load and a bit slower to go back again and batteries can more-or-less match renewables for rate of change. The superconductor solution is the fastest but also the most expensive per KWh of storage.

In the time before renewables all of the rate-of-change limitations came from sudden increases or decreases in consumption, never from the supply side and this has subtle implications for the structure of the power grid and how much power companies can do to control the match between the two.

Think of it as a person walking across a rope with a balancing pole: you can overbalance for a short while because you can correct for that with the mass of the pole. But if the overbalance is too large for the mass of the pole then you will inevitably fall (brownout, blackout).

"Superconductor solution": did you mean "supercapacitor solution"?

No, superconductor. Effectively an electronic version of the flywheel.

There is a company in the United States that has been making these for almost 20 years now, they are used for ride-through in hospitals and for windfarm output stabilization.

https://en.wikipedia.org/wiki/Superconducting_magnetic_energ...

https://www.amsc.com/gridtec/renewable-interconnectivity-sol...

Enjoy the read. It's interesting stuff.

It is indeed, but the refrigeration needed would seem cumbersome for most applications.

Not really, I've seen these units in the middle of the mountains sitting right next to a windfarm. About as inaccessible as it gets and yet they were there and humming along. Note that there is plenty of energy available for the refrigeration and that those units run for years unattended. Occasionally you need to top off the refrigeration gear but that's once every two years or so, a bit more involved than your average HVAC setup but not that much more involved.

Yes but we will get much more grid scale batteries anyway

It doesn't necessarily need to be non-renewables through. There just has to be spare capacity that the grid could count on being there. There just needs to be a way for the grid to pay for the capacity that's going to go unused a lot of times, whether it's batteries, extra water and turbine in a dam, or standby power plants.

It's quite likely that in the future electricity sellers will need to pay a tariff to cover the operation of flywheels.

Not sure why the cost would be borne by sellers. More likely consumers will pay for it as part of the grid infrastructure in my opinion.

Well, currently the sellers are the ones directly paying for the grid infrastructure.

It makes much more sense. They are the ones that can choose what part of the grid they plug on, and they are the ones choosing if they provide the service or not.

I dont think I agree.

Typically electric companies pay for the grid infrastructure and operation currently. Electricity producers like solar plants out in the desert is not paying to maintain the poles to your house.

Retail electricity companies pay only for their own grid. They aren't paying for the link between your city and the plant out in the desert.

maybe we have a difference in terminology. The interconnects between the grid and primary producers are often owned an managed by the retail company. Who pays for them is often a sticking point and can go both ways.

What I think is indisputable is that it is the retail electric company who manages and maintains their grid, and manages it's demand and stability.

>sellers are the ones directly paying for the grid infrastructure.

This is absolutely not the case for the vast majority of that infrastructure. You just mentioned small connections. If you look at the grid, it is basically all retail companies[1]

https://www.researchgate.net/figure/California-electric-grid...

You're using American-centric terminology that doesn't translate well to other countries, most of which have one national grid company that manages the transmission grid (which extends up to the generation facilities) and where 'retail companies' refers to local distributors who may operate their own distribution networks or who may just handle billing etc.

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