[mschuster91]

Not that much, grids can and do deal with highly variable loads all the time, as all the heavy machinery involved in traditional power generation (=generators, gearboxes, axles, turbines) has a lot of inertia that buffers sudden changes.

However, as more and more generation capacity shifts to renewable sources that by design have very small (wind) to zero (solar) inertia, there will be a requirement to build out frequency stabilizer units like the Tesla unit in Hornsdale, Australia [1].

[1] https://en.wikipedia.org/wiki/Hornsdale_Power_Reserve

[Dylan16807]

Advanced solar and wind inverters can also push back on grid changes to mimic inertia.

Also I'd say the inertia in a normal wind turbine doesn't count because it's not tied into the grid frequency.

[crote]

Aren't batteries quite limited in their ability to provide synthetic inertia? Sure, they can respond on a second or tenth-of-second scale, but they don't provide the kind of instantaneous inertia you get from spinning rust. Inverters aren't exactly designed to just eat power surges, they'll instantly disconnect instead.

That's why the UK grid has been building some "high-inertia synchronous compensators", and a 2019 outage showed that it's urgently needed.

[CorrectHorseBat]

Can't you make them behave however you want with sub millisecond reaction time?