I read about this a while back when I was in Australia, sadly they never got to build it there, but now Arizona has stepped up to the plate. I believe and hope the construction of this installation will show very clearly that large, industrial scale renewable energy systems are entirely possible and plausible.
The video explains it pretty comprehensively, but if you've ever been up in a microlite on a hot day wearing shorts and a T shirt (I have) you will know from bitter experience that the higher you go, the colder it gets. This whole system works on temperature differentials and the simple physical fact that hot air rises. Heat the air at the bottom of a very tall chimney and the air rises up the chimney. Put some very large turbines around the base and they will turn.
As EnviroMission CEO Roger Davey explains, this power station requires no 'feedstock.' It doesn't burn anything. To power the entire megacity of Los Angeles you would need 12 of these towers.
It's due to come online in 2015.