Is sterling engine efficient and economical?
Many attempts have been made to build Sterling engines, because of its similarity to the Carnot cycle, a theoretical cycle with the highest possible efficiency. However the practical problems involved have prevented widespread use of the Sterling engine. The biggest problem is that the specific horesepower is low because the mass of working fluid is low. People have tried using extreme pressure helium or even hydrogen to overcome this, but wear and friction on the seals creates too many difficulties. Sterling engines were popular in the late 1800s when specific horsepower was not so much of a concern.
