[Yasser]

Yasser  asked the Naked Scientists:
   
Dear Naked Scientists,
 
Concerning the debate surrounding the search for green-energy, would it be possible to put miniature turbine engines inside the smoke stacks of factories to convert the moving air being released into electrical energy?
 
Best regards,
Yasser in Canada

What do you think?

[LeeE]

I doubt the flow rate from a smoke stack would be high enough to drive a turbine.  There'd also be the problem of it being immersed in, then becoming coated, and eventually clogged, with the smoke particles.

[stereologist]

It might be possible to use the exhaust as a heat source that heats a fluid that drives a turbine outside of the smoke stack system. There are many different fluids that boil at different temperatures that might be used.

Here's a quick link to some ideas on using waste heat to run secondary power generation systems:
http://www.peswiki.com/index.php/Directory:Advanced_Power_Generation

I'm sure you can find better online references to such ideas.

[Geezer]

I saw something the other day about GM using memory metal bands running on hot and cold pulleys to recover waste heat from an IC engine's exhaust. Sounded a bit like a mechanical Stirling cycle to me. Unfortunately, that's about all it said, but a patent search might bring up more details.