brilliant!, WOW!, how the fuck did everybody else miss this till now! this could be easily cobbled together useing junkyard salvage! zero exotic anything! -37°c, I've lived in colder places. it will scale down to house or smaller sizes, or all the way up to primary grid power. far north areas with abandoned mines into the permafrost will benifit from this. very tickled by this edit: there are a number of hazards and failure modes that are unique to this , but in no way as a dangerous as most other current power generation and handling of chemical storage and transport, and most of the danger to the public can be eliminated by sufficient set backs, ie:in a breach the CO² would dissapate below lethal levels quickly.