Refrigeration systems account for nearly half of the electricity consumed by supermarkets. In order to save energy and reduce CO2 emissions, CO2 booster refrigeration systems have been developed. This paper discusses three of them due to their high energy efficiency, economic feasibility, and environmental friendliness for supermarkets of T & uuml;rkiye for the first time in the literature. These systems are the standard CO2 booster system (BRC), the CO2 booster refrigeration system with the flooded evaporators (BRC-FE), and the CO2 booster refrigeration system with the flooded evaporators and parallel compressor (BRC-FE-PAR). Power consumption values, coefficient of performance (COP) values, annual energy consumptions (AEC), installation and operating costs, and CO2 emissions of the systems are calculated and compared with the reference R404A refrigeration system (Reference System) under different climatic conditions. The highest COP values are obtained for BRC-FE-PAR under 30 degrees C ambient temperatures. Above this temperature, the Reference system has the highest COP. The BRC has the highest AEC, while the BRC-FE-PAR has the lowest among CO2 booster systems. The BRC-FE-PAR is the cycle with the highest saving (2.2%-19.4%) as compared to the Reference System in all cities considered. The investigated CO2 booster systems have lower emission values between 23.4% and 52.2% than the Reference System.