Originally Posted by Nausikaa
The Stirling engine was invented by a Scots minister, Robert Stirling, in 1816 so the concept is not new. It is used in Swedish and Australian submarines (Collins class) but if it is so old, reliable and fuel efficient why does it not have a greater following? The Whispergen is made in New Zealand.
I guess one of the reasons is that Stirling engine is good at generating low power from low temperature difference, but people usually more power hungry than that.
Wikipedia have a very good article on Stirling engines. The "Analysis" section should shed some light on the issues involved.
Some interesting quotes from other sections of the article:
The design challenge for a Stirling engine regenerator is to provide sufficient heat transfer capacity without introducing too much additional internal volume ('dead space') or flow resistance, both of which tend to reduce power and efficiency. These inherent design conflicts are one of many factors which limit the efficiency of practical Stirling engines.
Towards the end of the [20th] century, several companies developed research prototypes of medium-power engines and in some cases small production series. A mass market was never achieved because the unit costs were very high and some technical problems remained unsolved. Now in the twenty-first century, some commercial success is starting to become feasible, notably with combined heat and power units. """