This is one of the better questions I've seen on Yedda.
The Stirling cycle engine has been around for many years, but I would suppose it lost favor in bygone years due to cost effectiveness. I.E.: Cost to build, operate, and maintain vs the amount of work obtained from it.
Perhaps it IS time to revisit this principle with current technology. Didn't one of the car companies (Mazda, perhaps?) look at this a few years ago?
While I "haven't done my homework," I would suspect cost effectiveness would be at least one answer to your question. I have "run the numbers" on both solar and wind power alternatives and neither are really cost effective (in their present state) in my geographic area.
Would hope that someone smarter than I am spends the time to look at this closer. The above is merely off the top of my head.
