This already exists. The national grid crosses state boundaries and often power generated in one state is used in another. This author is ignorant of the subject matter. As for doing without fossil fuels, this works only if you ignore math entirely.
I don’t think the grid is nationalized. States make their interstate agreements don’t they?
Also some States like Texas have their own separate grid.
Ignore not only math, but physics, thermodynamics, all power engineering principles, basic engineering economics, and common sense.