Technologies left behind: Steam

I've always been fascinated by steam engines. And I think it's a real shame they aren't sill prevalent. Theoretically, a steam enginecould be as powerful as one would like. You could move the earth with a steam engine if you just built it big enough. Just build a boiler about 100,000 miles across, set it next to the sun, and build a piston about the size of the moon, a connecting rod 1 AU long and before you know it, you're playing billiards with planets.

Okay, perhaps that's a stretch of unimaginable porportions, But My point is made. The steam engine can be built to whatever power level is desired. Just make the parts beefier and bigger, and apply more heat to the boiler, viola!! more power.

Contraptions of unimaginable size and complexity could be powered by steam, Machines of war, machines of peace, machines of whatever. All those massive, walking mechs you see in cartoons, Alot of the largest ones could only be powered by steam. (the ones the size of a car could use electric linear actuators, and ones up to about 40' tall could use hydraulics, but the REALLY BIG ONES, the building crushing, ground rumbling mechanical monsters on the other hand, are about relegated to steam power.)

Plus, if you have an appropriate heat source, steam power is completely clean, it doesn't even use non-recycleable components.

I like steam, I wish we still used it more.