Why, sure. It would be good to know how long a conventional generator can keep running when everything around it has gone wrong. For coal, for instance, that might be represented by the mass of the piles of coal that are normally on-hand -- or by the electricity (in MW-h, say) those piles of coal should be able to produce. Having this information close by would seem to be a good thing for an organization like ERCOT, so as to be factored into their emergency playbook.
But that's still a different case than a battery, wherein: Even if everything is going right, using energy from a battery must eventually cause it to become depleted.
It's never like a coal plant that (ideally) consumes fuel at one end, and spits out electricity at the other end as a continuous process. A battery, in this context, can be in a charging or a discharging state, but it can never be in both of those states at the same time -- using a battery is not at all a continuous process.
But that's still a different case than a battery, wherein: Even if everything is going right, using energy from a battery must eventually cause it to become depleted.
It's never like a coal plant that (ideally) consumes fuel at one end, and spits out electricity at the other end as a continuous process. A battery, in this context, can be in a charging or a discharging state, but it can never be in both of those states at the same time -- using a battery is not at all a continuous process.