RTFA: http://en.wikipedia.org/wiki/Sterling_engine

In the family of heat engines, ‘Stirling engine’ defines a closed-cycle regenerative hot air engine, though the term is often used incorrectly to refer generically to a much wider range of hot air engine types. In this context, “closed-cycle” means that the working fluid is permanently contained within the system, whereas “open-cycle” engines such as internal combustion engine and some steam engines, exchange working fluid with their suroundings as part of the cycle; “regenerative” refers to the use of an internal heat exchanger - the regenerator - which greatly improves the engine’s potential efficiency. There are many possible implementations of the Stirling engine, the majority of which fall into the category of a reciprocating piston engine. The Stirling engine is traditionally classified as an external combustion engine, though heat can equally well be supplied by non-combusting sources such as solar or nuclear energy. A Stirling engine operates through the use of an external heat source and an external heat sink, each maintained within a limited temperature range, and having a sufficiently large temperature difference between them.

This engine is very versatile because it only requires a heat difference to work. It is a closed system, unlike internal combustion engines, which is just another reason this engine is really cool.

RTFA: http://rtfa.net/

a low-volume blog clearly citing interesting content with minimal editorializing

It is with great pleasure that I am introducing the newly redesigned RTFA to the Internets.

Behold! A number of improvements are worth reflecting upon.

1. classic article format links straight to the fucking article
2. clearly identified excerpts!
3. new editors, and more of them!
4. stable software to drive the blog!

That’s right. ”Classic RTFA” is back! It was just too new for the Internet to handle when we first launched, way back in October of 2004, so here’s a second chance for humanity.