What Do They Run On? Sterling Silver? <g>

[Coast Guard Kiteman <exfloridians@ecsu.campus.mci.net>]

        Here's another question.  I've mentioned two books about subs
referring to "Air Independent Propulsion" (AIP) using Sterling engines.
The way I understand Sterlings, they're a 'closed-loop' hot air engine
that can use any heat source.  What I don't understand is WHAT
everyone is using as a heat source?  A chemical reaction?  Burning
two fuels like oxygen and hydrogen?  Anybody have any ideas?


[One of the two books is "SUBMARINE: A Guided Tour Inside A Nuclear
Warship", by Tom Clancy.  The other is a fictional novel involving a
German-designed AIP sub in use with the U.S. Navy.  I can't remember
the name or the author.]