Our pal I-Wei Huang, of Crabfu SteamWorks, sent us a link to this “green” steam engine, a super-efficient two- (or more) piston engine that is allegedly easy and economical to build. It has a very ingenious way of converting reciprocating movement into rotary movement, the action of which you can see in an animated GIF on the site. It’s amazingly efficient, (freewheeling at a mere 2 psi).

Green Steam Engine Home Page – Link