OTEC ocean power

OTEC is ocean thermal energy conversion.  It is related to geothermal but can be used on 3/4s of the earth's surface. (much better)  It takes the energy difference of surface water and deep water to create hot and cold places that power a heat engine.  The sun supplies energy to this by heating the ocean saltwater.  Lots of times an ammonia boiler is used but Stirling engines would also work.
http://www.otecnews.org/