We already build grids of grids https://en.wikipedia.org/wiki/Wide_area_synchronous_grid https://en.wikipedia.org/wiki/Wide_area_synchronous_grid The European

We already build grids of grids https://en.wikipedia.org/wiki/Wide_area_synchronous_grid https://en.wikipedia.org/wiki/Wide_area_synchronous_grid The European one is quite impressive and grows at a fair pace: https://en.wikipedia.org/wiki/Synchronous_grid_of_Continental_Europe https://en.wikipedia.org/wiki/Synchronous_grid_of_Continenta... Physically interconnecting distant grids (the Intergrid (?!)) may be possible thanks to new ways such as HVDC. See https://en.wikipedia.org/wiki/Australia-Asia_Power_Link https://en.wikipedia.org/wiki/Australia-Asia_Power_Link However maintaining grid stability (at each and every moment: volume consumed = volume produced) and therefore regulating physical parameters (such as tension, electric curent...) in in real time (they all are to stay nearly the same everywhere) may be major challenges. A classical problem is: overload on a segment, you have to cut it, overloading another one... and such a cascade can bring the whole thing down in tens of seconds.