In reply to Horace Heffner's message of Thu, 14 Apr 2005 09:04:33 -0800: Hi, [snip] >The rise column (or draft tube as you call it) should be cheaper to >implement as a single flat cross section than as multiple tubes. The sides >not against the mountain must be insulated to preserve the temperature of >the air in the rise column, because its bouyancy is what drives the device.
Alternatively, one could make the outside of transparent material, and the mountainside black, so that the whole chimney collects extra solar energy over its whole height (vertical greenhouse). BTW there are some low mountains in central Australia, in the middle of the desert, that run more or less east-west, and have steep sides. Perhaps not as high as one might like, but it would make a good start. Regards, Robin van Spaandonk All SPAM goes in the trash unread.
