Replacement gas fired power stations

[dan_b]

That's one of the ways the Grid maintains frequency at 50Hz- the "inertia" in those big spinning machines. The Grid is learning how to manage with a lower penetration of spinning reserve to do that - which includes batteries which can provide extremely fast electrical response

[Mart]

Tesla has started to launch 'virtual machine mode' with their Megapack batts, to simulate/fake inertia.