Engineering issues aside, to evaluate if a super chimney would be energetically viable you need to understand the concept of "Convective available potential ene

Engineering issues aside, to evaluate if a super chimney would be energetically viable you need to understand the concept of "Convective available potential energy" or CAPE--https://en.wikipedia.org/wiki/Convective_available_potential_energy https://en.wikipedia.org/wiki/Convective_available_potential.... CAPE has dimensions of energy/mass and a describes how much energy is released by raising a mass of air to some higher elevation. CAPE is used to forecast storm development, as updrafts can more likely spontaneously form when there is more energy released by the updraft. CAPE values can also be zero or negative, in which case there would be no available energy to sustain an updraft. From my understanding, CAPE is the only factor that would determine if a super chimney could work at a given time. I have not found a good resource on global CAPE patterns including daily patterns, but it seems very likely that there is any fixed location and fixed elevation that always has a positive CAPE value. It would be an absolute requirement to find such a location for this project to work. You should also be able to calculate a crude bound on the maximum updraft velocity simply as a conversion of potential energy to kinetic energy. Wikipedia says that exceptionally high CAPE values proceeding extreme thunderstorms are around 5kj/kg, which would accelerate a mass from rest to 100m/s (220mph). Of course this is an extreme value, typical values are more like 1kj/kg, which correspond to a velocity of 44m/s (100mph). Here is a really good paper on CAPE and atmospheric convection heat engines: http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281996%29053%3C0572%3ANCAAHE%3E2.0.CO%3B2 http://journals.ametsoc.org/doi/pdf/10.1175/1520-0469%281996...