James,

On Tue, 27 Sep 2005 15:25:59 -0600, James Humes wrote:

> Here is an idea i had when in school after seeing a small stirling engine
> that operated by placing it on top of a mug of hot coffee... after you
> helped the engine overcome starting torque, it kept itself quite nicely.
> Ignoring feasibility (I did major in math, we're allowed to do that), my
> idea was to build quite a few stirling engines along those lines but upside
> down.. (ie, the cooling section is on the bottom). Now, bury the cooling
> section and leave the part you must heat above ground in a sunny place. Once
> the temperature differential is in the right place, give them a start. So,
> on each engine we put a small generator and trickle charge our batteries.
>  Go ahead, I'm ready for all the many things I haven't thought of that make
> this a bad idea:p

Well you've just described a solar powered Stirling engine - or an array of them.  Nothing wrong with that, 
but you have to get rid of the heat from the cold side - just burying it would heat up the ground underneath 
and it would stop.  Set up convection cooling, using a chamber underneath leading to a chimney, say, and you'd 
have a better chance.  The feasibility problem comes from the efficiency - low temperature-differential 
Stirlings aren't very good, so you may not find much usable power.  They'd go round, but they might not have 
enough power to turn anything useful like a generator!

Cheers,

Howard Winter
St.Albans, England


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