, last nites questain /what makes a chimney draft,/ asker satisfied by answer/ left open ideal,/,i find interesting chimneys draft up when hot or warm outside down when cold out side this is considerable complaint by many loss of heat loss of cold air etc MY QUESTAIN is the ongoing draft useable as a source of power were all familiar with solar ,hydro ; and wind power solar stops with clouds , darkness, snow .wind stops that halts turbines, according to last nites premature stop to replies ,, drafts dont,, how feasable is putting small turbine fan in a chimney cap, or stack to capture that power wheather by natural draft ,common use of fire place wheather by gas or wood , powering the fan is not the idea just using what occurs naturaly or as by product of use i realize minimal production capacitys and not intended to put txu out of business .i would imagine used in roof turbine vents already but havent inquired,with the go green section as to roof vents that could be used on a chimney if you have one does it work