In alt.home.repair on Mon, 14 Jul 2003 14:11:47 -0700 "Steve" posted:
How can it be both powered (spun) by the air flow and accelerating the air flow? Is it taking energy from the air or lending energy to the air?
If it were to do both, doesn't that sound like a perpetual motion machine?
Maybe turbines slow down the air less than ridge rails, and the only benefit of a turbine over a hole in the roof is that it keeps the rain out (while slowing the air down less than would be the case with say, a roof fan housing without the fan. Where the air has to go up, then sideways, and then up again.
Meirman
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