This is really interesting. That said, it looks pretty straightforward to build; looks like there are no novel materials or equipment needed to make this happen, from my reading of it. Given that, why don't we have a full-scale prototype of this, at the very least? Is it just the money, or is there something non-trivial about this? I feel like I'm missing some reason why this is non-viable in practice.
<a href="http://en.wikipedia.org/wiki/Energy_tower_(downdraft)" rel="nofollow">http://en.wikipedia.org/wiki/Energy_tower_(downdraft)</a> Downdraft tower seems similar. In theory could produce 400MW in a small area and solve our energy problems.