To extract energy from the sun there are a lot of different ways. According to my knowledge the ones that receives most of the attention are photovoltaics, concentrated solar power, and the Solar updraft tower. The first two solutions reached commercial scale. There are already many photovoltaics plants operational and few CSP plants. The updraft tower instead seems locked in an eternal study phase. The first proposal was made about one hundred years ago, if you search of the internet you will find a lot of studies experiments and cost evaluations, many of them conducted by major universities. But as far as I know there have only been few small scale experimental plants.
I remember seeing some comments in the Wikipedia talk that described the idea as a fairy tale due to the low efficiency that render the ratio cost/output too high. I can't find those comments anymore but still this archived discussion expresses a lot of scepticism.
On the other hand if the idea is really so infeasible it seems strange that so many resources were dedicated to the studies, there are also dozen of patents related to the technology and patents have a cost.
As far as I know all the proposals for a commercial plant have been silently abandoned. Am I correct? Is there any ongoing project? Does it have any chance to reach commercial status?
Please restrict the answers to the Solar updraft tower.