> Could a Stirling Engine be used on the exhaust gases from a furnice to produce electricity and raise the furnice efficiency. > In concept yes, but in practice this would be an expensive exercise for what was achieved and only a small portion of the furnace's waste energy would be liable to be able to be regained. Spending the money on more insulation would probably be a better choice :-) RM -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics