Reclaiming Wasted heat to make electricity
I work in an aluminum casting facility and we're looking for ways to save energy etc...
one thing that we've got no shortage of is heat (during the summer the temp near the ceiling above the furnaces is over 230F)
i've looked into stuff like they do in steel mills in Germany where they run pipes through the furnace linings and then use the heat from the furnace to make steam and run steam generators.
but i was thinking of something else today. would you be able to just mount a bunch (or one huge) peltier exchanger (or whatever they're called) on the ceiling above the furnaces and use that to make electricity? i'm aware that they create electricity because of temperature differences (and not specifically from being hot or cold in general) so would we have to cool one side of the unit for maximum efficiency?
are there any other ways that anyone knows of to turn waste heat directly or indirectly into electricity?