CO2 offers a wealth of benefits for industrial refrigeration

The high-stage system cools the liquid R744 in the secondary circuit. The R744 is pumped around the load. It is volatile, so unlike a conventional secondary fluid such as glycol it does not remain as a liquid. Instead, it partially evaporates, providing a significantly greater cooling capacity. This reduces the pump power required and the temperature difference needed at the heat exchanger.

R744 would typically be cooled to -3°C for the MT load.
The high-stage system is a simple chiller-type system, typically running on an HFC, HFO or Ammonia refrigerant.