flywheels don't really work synchronously, though. Or at least, if so, they're not very useful as storage. Inverters can simulate inertia just fine, in fact the

flywheels don't really work synchronously, though. Or at least, if so, they're not very useful as storage. Inverters can simulate inertia just fine, in fact they can simulate a much larger inertia than the corresponding power of spinning generation, leading to greater grid stability (whether connected to batteries or solar/wind, though without batteries its a little 'brittle' if you run near 100% output, as the power needed may suddenly disappear, so this is probably not good practice for the system as a whole. And you still need some give in your inertia so the grid can actually communicate about supply and demand)