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[DaS Energy]

All fridge have first purpose to chill the refrigerant. Warming a refrigerant provides an expansion force. Turbine with shaft pump first takes the forces of the expanding refrigerant to drive the turbine. On escape from the turbine the refrigerant chills. After chilling it is pumped back into the boiler.  Ground heating from -40*C up is sufficient heat for operation.

[LibreEnergia]

All fridge have first purpose to chill the refrigerant. Warming a refrigerant provides an expansion force. Turbine with shaft pump first takes the forces of the expanding refrigerant to drive the turbine. On escape from the turbine the refrigerant chills. After chilling it is pumped back into the boiler.  Ground heating from -40*C up is sufficient heat for operation.

Except that this concept runs headlong into the 2nd Law of thermodynamics whether you like to admit it or not.   If you had a 'ground heat' reservoir at -40 then you better hope you have a sink at a lower temperature than this for the concept to work at all. It does not

I'd suggest your -40 heat reservoir is far more likely to be the low temperature sink rather than the source, and then yes it would work in the opposite direction in most temperate climates. Good luck on finding that - 40 C heat sink.

[DaS Energy]

Same workings as all absorption  fridge, hot high pressure gas turns cold liquid at choke point. Replicated by turbine. You have one second to achieve a heat intake. Ist law of physics Einstein -high pressure-not pressure loses heat! CO2 preceded Ammonia as a  Refrigerant. 2002 NASA and DaS Energy published to its come back! It not a posted therom! It steam low pressure home made, outmoded in gas  turbine CO2. It require shaft be machined!

[DaS Energy]

Sorry a PS if I may -40C is flash point of dry-ice to gas. liquid comes later. More workable is -10*C up.

[DaS Energy]

"I'd suggest your -40 heat reservoir is far more likely to be the low temperature sink rather than the source" No, the cold sink is lower than -40*C without that no heat expansion occurs at -40*C.
The cold sink being lower temperature than the heat temperature for gas expansion must always occur if the mechanism to operate.