Science Buddies: "Ask an Expert"

This is a weather/science question.
The company Solar Wind Energy Tower has a idea/concept for energy and they made a video on their site about how it works. I am curious to anyone with some expertise and scientific analysis background to post what they think, if possible, if not, potential problems etc.
( THIS IS NOT SPAM OR ANY JUNK POST, It is a serious question and I would love some input)

Here is their site with their flash video.
( I do not work or am affiliated with this company I am just a nerd and am extremely curious)

http://www.solarwindenergytower.com/the ... l#towervid

Dear 2k1civicmike,

I am a retired electrical engineer. My take on this "solar wind" system is that as I looked at the website you referenced, there appears to be a paradox. Near the beginning if the theory of operation they state that "hot dry air which has been heated by the solar rays of the sun" evaporates the water, becomes cooler and moves to the bottom. Later on they state that this produces electricity 24 hours a day. How is this possible when the tower only works if hot dry air is present which assumes that the sun is shining ?

Having said that, I am assuming that you want to construct a considerably smaller version. I'm not sure if the unit can be successfully scaled down and still work but it would be interesting for you to try. Good Luck.