Re: At scale??? Yes, easily
I'd like to see how the author came up with that cost estimate. Specifically, how he costed the >200 TWh of storage and the TW-capacity global (i.e. trans-oceanic) transmission grid, and what he has allowed for losses during storage and transmission. And what assumptions he made about the cost of land to put all this infrastructure on. Also the maintenance and depreciation of the solar panels themselves...
Once we've thrashed all that out, we can begin to think about the politics. Which specific Saharan country should be entrusted with producing all the world's energy? How would we ensure that countries couldn't hold a "downstream" country to ransom by threatening to cut its supply?
Once we've answered those, then we can begin thinking about little details like who, specifically, is going to build and run this thing. I can't offhand think of any engineering company that has ever delivered a project of 0.1% of this scale for less than 400% of its original budget.
Biting the hand that feeds IT
