Aluminum has higher specific conductivity than copper by mass. So if you think you need 1 MT of copper conductivity, you can do the job with 0.5 MT of aluminum.
Aluminum is also quite abundant. Rate limits will be political rather than production. That's not to say this is a realistic idea or that it's worth doing, just that it isn't unthinkable on a resource basis.
https://www.anixter.com/en_us/resources/literature/wire-wisd...