Which says it all. After two centuries of development. My work is done here.

An officemate of mine got into Stirling engines for use in space applications. One was to use solar radiation as the heat source for power generation, but he focused on running the cycle in reverse to produce cryogenic temperatures. A quarter century ago, I was designing a cryocooler, for freezing animal tissue samples aboard the ISS, using his Stirling cycle engines, but NASA decided that, as a partner, Germany should have a project to work on, so they gave them my project.

That was when I got out of design and into assembly, integration, and test of commercial communication satellites.

What Stirling engines *do* provide, and the very thing that Rev. Stirling was attempting to accomplish, is that they completely replace the high-pressure steam used in a steam engine, and all of the dangers that accompany it. They also have the huge potential advantage of being completely fuel-agnostic heat engines. A Stirling engine doesn’t care where the heat comes from, as long as there is a temperature differential between the sink and the source. The heat can come from petroleum products, or a wood fire, or concentrated sunlight, or nuclear decay. It just doesn’t care, and that gives the Stirling engine some real, if uncertain, potential even today. In recent years, there was a company trying to hype up Stirlings with reflectors as superior to photovoltaics, and NASA was looking at them for use with RTGs. I wouldn’t mind having one as a backup generator, if anybody would make one for sale at a reasonable price.

The closest alternative to what a Stirling can do is probably the Thermoelectric Generator (TEG). Like the Stirling, the TEG is a fuel-agnostic heat engine, producing electricity in a similar manner to PVs rather than shaft horsepower like a Stirling. And, like a Stirling, it can be run in reverse, using electricity to provide refrigeration on one side.

https://en.wikipedia.org/wiki/Applications_of_the_Stirling_engine