LTD stirling engines are an interesting idea. They harvest the temperature difference of the environment versus a cold object, and using this they power some pumps.
How To Make a Low Temperature Differential (LTD) Stirling Engine
How To Make a Low Temperature Differential (LTD) Stirling Engine
(via www.greenoptimistic.com)
Submitted by sweet_andra87 on Fri, 2008-04-11 08:55. | Tags: technology | boat | heat energy | how to | stirling engine