Opinions of the STERLING Motor

[Cherryman]

User Cloudseeder over on "that other FE forum", proposes an engine that is driven by an extreme heat/cold differential. Super hot steam, and supercooled liquid air, meeting in a chamber. The steam collapses, pulling a vacume. As I envision it, the piston pulled in will be chased by rushed in steam, which then sees the same fate meeting the drop of air. I can see that being way powerul, but have difficulty calculating the energy cost of the required liquid air and supersteam supplies. The implosion of steam to water is a violent one though, I can imagine that there is OU to be had as it just takes up SO much more space than liquid water.
The water and air are part of a closed circuit, are not used up, but rather recycled. The whole engine would supposedl be temperature neutral, rather than radiating heat as waste product.

Perhaps we should look at various elements or substances with each their own unique melting points. Water turns steam at 1 bar by 100ºC. A bit high of a range. Something that boils at a bit lower temperature, perhaps? Or, have a heat exchange full device be enclosed, at partial vacume, optaining more preferable result even with plain water? Hmmm...

So if i can get water by weight under a pressure of 1 bar I get steam?