Stirling Engines. Why don't we use them more? askscience

It seems as though there are lots of places where a fairly extreme temperature differential exists. (I'm thinking radiators in cars, A/C, refrigerators). Why aren't we using this spare heat to do even more work?

Submitted November 12, 2014 at 01:18AM by b25mitch http://ift.tt/10Wbfy1 askscience