At the 2023 United Nations Climate Change Conference (COP28) in Dubai, 63 countries, including the U.S., signed a global pledge to cut emissions by 63% compared to 2022 levels by 2050. The pledge signals continued commitments by countries to adopt sustainable refrigeration as temperatures rise and drive up the cost of cooling. U.S. support for the pledge could mean increasing regulations within the country, driving supermarkets and food retailers to adopt cooling systems with a reduced climate impact, such as CO₂ refrigeration.

Fortunately, the U.S. is not embarking on this transition alone. In Europe, over 68,500 grocery stores use CO₂ refrigeration as a safe, natural refrigerant option. This article will cover some of the newest opportunities American supermarkets can consider when building CO₂ refrigeration.

Favored Choice

CO₂ is favored as the natural refrigerant choice for commercial applications because it is nontoxic and nonflammable. It has a low GWP of 1, which helps companies adopt sustainability initiatives and mitigate their environmental impact. Further benefits of CO₂ refrigerant include:

• Lower refrigerant costs than HFCs per pound;
• High heat reclaim capability; and
• High density requiring smaller pipe diameters.

For U.S. supermarkets starting to invest in sustainable refrigeration, CO₂ offers a proven, cost-effective, and fast way to meet regulations and reduce climate impact. Some of the newest opportunities in CO₂ refrigeration for supermarkets in the United States include:

1. Cutting-edge, energy-efficient technology: New energy-efficient components, such as pressure exchangers, can be integrated into new and existing CO₂ systems to drive greater energy efficiency. For existing systems, the pressure exchanger can also be integrated to expand cooling capacity.
2. Reduced operating costs: Although the initial upfront cost of a typical CO₂ booster system is greater than that of HFC systems, the total annual operating costs for CO₂ have been estimated to be less compared to HFC systems. Additionally, HFC refrigerants cost $5 to $7 more per pound compared to CO₂ refrigerants, and these prices are expected to increase as HFC production starts to ramp down in 2024. Commercially available components like pressure exchangers can also lower the operating costs of CO₂ systems by decreasing ongoing water and electricity bills.
3. Increased training program availability: Although CO₂ systems operate at high pressures, they are as safe as any other system, when designed and operated properly. Training programs are available through manufacturers, service contractors, and trade colleges with organizations such as the North American Sustainable Refrigeration Council (NASRC) facilitating them. These programs help equip technicians with the knowledge they need to service the future of refrigeration.
4. Low GWP: CO₂ refrigerant is a popular option because of its low GWP. In fact, the most abundant HFC will warm the planet 3,790 times as much as CO₂ over a 20-year period. By choosing CO₂, supermarkets can future-proof their systems against upcoming regulations.

Recent Innovations

Recent technology innovations such as the pressure exchanger continue to drive the efficiency and reliability of CO₂ refrigeration systems. For example, Energy Recovery’s PX G1300^® pressure exchanger captures the high-pressure energy of CO₂ systems to reduce electricity consumption. It transfers energy from high- to low-pressure CO₂, much like a heat exchanger that exchanges heat between two fluid streams. The PX G1300 increases cooling capacity and system stability by providing expansion and compression while reducing energy use.

Vallarta Supermarkets in the desert of Indio, California, installed the PX G1300 into their CO₂ refrigeration system and observed an additional 30% energy savings at 95° to 100°F. In collaboration with Epta, an independent global leader in commercial refrigeration, the pressure exchanger has also been installed in a transcritical CO₂ system at a supermarket in Italy. Using the PX G1300, the supermarket observed efficiency improvements of more than 25% at 95° to 104°F and more than 30% above 104°F.

Grocers and food retailers looking for sustainable cooling options can adopt technology such as pressure exchangers with their CO₂ systems to increase energy efficiency while meeting climate goals.