Except his calculations seem all wrong. From the article picture above there's no way that factory only has ~100x100 sqm (1ha - a bit bigger than a soccer field). Maybe 100ha. And that seems to be the case:

http://cleantechnica.com/2014/09/12/tesla-gigafactory-huge-2...

If he got that wrong (which seemed obvious to me from the picture of the Gigafactory alone), who knows what else he got wrong.