Power translator

Basically I want an electric superturbocharger that can work with a closed loop supercritical Co2 system, so that it can exploit a heat difference between a heat source (say a fireplace or car engine) and a heat sink like a radiator or flowing water to generate electricity, or use electricity to generate heat or pressure (which are pretty closely related in a supercritical fluid/gas). Size somewhere in the .5 to 5 Kilowatt range, prioritizing low maintenance and durability. Lighter and more compact is better, but it can be a decent size if it has to be. I'm planning on likely charging the system with pressure relief valves on the pipe system, and putting a piece of dry ice and sealing it, letting the sublimation charge the system until the pressure is relieved by the valves.