Yes, that's quite likely how they come up with this number. But is it enough? What's the most energy dense configuration that can be made with room temp SC and does it compete with lithium batteries?
"""
Although the attainable magnetic flux density limits the energy per unit volume given by
Equation (1) ( B2 /2μ o), the real limit of the energy stored in a SMES is mechanical.
[...]
The relation defines the
minimum mass of the mechanical structure in pure tension to support the radial
electromagnetic forces. Force-balanced coils [5] minimize the working stress and thus the
mass of the structure.
"""
So it looks like they 1) don't look at cryo and 2) the limiting factor is the stress due to EM fields.
