It bothers me that you attribute this to Elon Musk. This has been obvious to everyone for 75 years or more. The lecturer in my freshman thermodynamics class mentioned it, 35 years ago. In 1999, NREL scientists writing in the journal Science under the title "A Realizable Renewable Energy Future" made the specific claim about 10000 square miles.
People of a certain world outlook will listen to Musk when they'll ignore more enlightened commentators. That's a good thing.
> Elon Musk mentioned [...]
He didn't say Elon was the origin.
Thank you. I was not aware of prior references especially that it could be done with 10K square miles, until media reports of Elon's speech at Davos recently.