I am not a EE, but a 10 MW generator is not physically that large. I have seen giant flywheels that store a lot of energy and are spun up by a smaller motor on the other end running continuously (TUM / IPP fusion reactor energy storage near Munich). You could imagine putting something like that in to avoid fouling the power grid with 30 second 10 MW spikes.
I think the problem is letting a human connect these things. Maybe if you automate all the connections, similar to the Tesla battery swap stations? That and lifetime of the electrodes.