Host Jamie Kitchen and guest Jorg Saar compare CO₂ with A2L/HFO-HFC blends and A3 options like propane (R290), explaining why CO₂ isn’t new, what transcritical operation means, and why CO₂ can excel at heat recovery (especially in supermarkets). They also cover the tradeoffs—high pressures and added complexity for CO₂ versus flammability considerations for A2Ls/hydrocarbons—concluding there’s no one-size-fits-all refrigerant; the best choice depends on the application.