Nano Stirling Engines

[SCollins]

For those of you who don't know, a Stirling Engine is a device that
generates rotational motion from a very low temperature gradient (like
the heat generated by a cup of coffee, or a bag of ice). They're
usually not practical because they have a low torq, can't vary in
speed, and (becuase they run off of a low temperature gradient) they
aren't exteremeley efficient). But I think that can be changed. Imagine

a microscopic engines coating the traditional engine of a car,
capturing a substancial fraction of the energy that is usually
disipated in heat. Imagine a coating on the walls of houses that could
be used to power that same house with electricity, by harnessing the
temperature difference between the inside and the outside. Imagine a
power generation system that uses shallow pools of water, coated with
thin film (like oil) that's generating electricity both night and day.
I beleive nano-stirling engines could be a monumental scientific
achievment if they were achieved. Is anyone else interested? Does
anyone have the expertise to help design one?