[willis936]

I'm pretty sure you can pick coil geometries that cancel external magnetic fields. There may be some stray fields, but they can be quite modest with tight manufacturing tolerances.

It's an interesting idea worth exploring. The two places where I think feasibility may face challenge is in the energy density gated by critical current density and magnetic field and in raw discharge rate (giant inductors are not known for being able to change their current quickly).

Knowing peak capacity and aging is also tricky since you can't measure critical limits without hitting a quench (a very, very bad scenario). You'll need to maintain healthy margins so you don't have things blowing up on sunny days or after so many charge/discharge cycles.

[peterfirefly]

The energy density is absurdly low.

https://en.wikipedia.org/wiki/Superconducting_magnetic_energ...

Compare with this table:

https://en.wikipedia.org/wiki/Energy_density#In_chemical_rea...