How do you think electricity is generated?

Present renewable energy is not efficient enough to replace it at scale, either. Solar will never get more efficient than it is; even Elon has acknowledged that.

Hydro is expensive and requires a lot of maintenance, as well as a place to actually install it which will also take a substantial amount of time and money.

Wind is deadly for the environment, extremely inefficient and takes up space it doesn't need to.

The best route is nuclear, though eventually nuclear waste becomes a lot of space too.