Megan Rodriguez, Grocery Outlet, discussing the chains transition to natural refrigerants at ATMO America 2024.
Megan Rodriguez, Grocery Outlet, at ATMO America 2024.

ATMO America: Grocery Outlet Explores Options for Natural Refrigerant Retrofits and CO2 Systems Nationwide

The U.S.-based discount food retailer has already specified transcritical CO2 refrigeration as standard for its new stores in California.

U.S.-based discount food retailer Grocery Outlet has said it is exploring opportunities to retrofit its existing stores with natural refrigerants and expand its use of CO2 (R744)-based refrigeration in new stores nationwide.

Having already specified transcritical CO2 as standard for its new stores in California, all of the company’s 16 R744-based systems are located in the state, explained Megan Rodriguez, Senior Manager of Refrigeration at Grocery Outlet. Four of the five Grocery Outlet stores using propane (R290) refrigeration technologies are also located in California.

The retailer’s focus on the state has been driven by California Air Resources Board (CARB) regulations that require new stationary refrigeration systems with more than 22.7kg (50lbs) of refrigerant to use refrigerants with a GWP of less than 150. According to a factsheet published by ATMOsphere, publisher of, both CO2 and R290 have a 20-year GWP of one or less.

By the end of 2025, the retailer plans to have a total of 38 stores using transcritical CO2 refrigeration systems, she added.

Rodriguez shared details of the chain’s transition to natural refrigerants during her presentation in the End Users Panel at the ATMOsphere (ATMO) America Summit 2024. The conference took place June 10–11 in Washington, D.C., and was organized by ATMOsphere.

Founded in San Francisco in 1946, Grocery Outlet now has 481 stores across the country. Having opened 81 stores since 2021, the company has been expanding rapidly over recent years. While the majority of its locations are along the west coast, the chain also has stores in Delaware, Maryland, New Jersey and Pennsylvania.

Grocery Outlet stores, which are 12,000–18,000ft2 (1,114–1,672m2) on average, are independently owned and operated. However, the chain decides on store design and purchases, installs and maintains its ownership of equipment such as refrigeration systems, explained Rodriguez.

The benefits of CO2

Grocery Outlet opened its first CO2-based store in 2020 in Sacramento, California. The system consists of a transcritical booster with adiabatic gas cooler, manufactured by OEM Hillphoenix.

For this installation, the company took advantage of financial incentives through the Sacramento Municipal Utility District (SMUD) and the North American Sustainable Refrigeration Council (NASRC). In total, Grocery Outlet received $217,000 (€202,732) in funding for the project: approximately $79,000 (€73,805) came from SMUD’s natural refrigerant incentive fund, $13,000 (€12,145) came from the utility’s energy efficiency incentive fund, and $125,000 (€116,781) came from an American Public Power Association (APPA)’s Demonstration of Energy and Efficiency Developments (DEED) grant.

According to a study conducted by Hillphoenix, the CO2 system reduced energy use by 27% compared to the R404A-based system of a similar Grocery Outlet store nearby. During her presentation, Rodriguez shared results from another Hillphoenix study that saw energy savings of 15% compared to an R448 alternative.

“Our operators pay 100% of their energy bill, so we’re always looking for ways to reduce their energy costs,” she said. To ensure the optimal performance of CO2-based refrigeration systems in warmer climates, the company is currently exploring options for boosting efficiency, she added.

Beyond energy savings and regulatory compliance, the retailer has seen multiple benefits of CO2-based refrigeration compared to traditional HFCs, including lower installation and refrigerant costs.

“Our experience with it has been pretty positive,” Rodriguez said during her presentation. “The [environmental] impact, total cost of operation, installation cost and startup cost for charging the full CO2 system is definitely lower.”

Despite these benefits, the company still has some concerns as it continues to adopt CO2, including higher equipment costs, refrigerant availability and leaks.

“Training is also a concern for us; [however,] we are feeling pretty comfortable [with] expanding our CO2 footprint with the training programs that are [currently] out there,” she explained.

“Our experience with it has been pretty positive. The [environmental] impact, total cost of operation, installation cost and startup cost for charging the full CO2 system is definitely lower.”

Megan Rodriguez, Grocery Outlet

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