Global cold storage logistics provider Americold sees packaged low-charge ammonia (R717) and transcritical CO₂ (R744) refrigeration systems as blueprints for new cold storage construction and retrofits of legacy systems, according to Nicholas Fletcher, Senior Manager of Design Engineering.

Fletcher detailed the provider’s operations, its decision processes for refrigerant selection and two new sites under development in a presentation at ATMO America 2025. The event, organized by ATMOsphere, publisher of NaturalRefrigerants.com, was held June 11‒12 in Atlanta, Georgia.

“Highly reliable large central ammonia systems, which make up over 80% of our operations, are not right for every project,” Fletcher said. “Manufacturers are addressing our flexibility and maintenance needs with scalable packaged solutions in multiple sizes.”

Operations/targets: Americold, headquartered in Atlanta, Georgia, operates 239 cold storage warehouses in 12 countries, with 83% of its sites using ammonia refrigeration, 15% synthetic and 2% CO₂ cascade systems. By 2030, it aims to reduce its Scope 1 and 2 emissions by 30% compared to its 2021 baseline.

• “The majority of our storage is frozen, and we use a lot of energy to keep it cold, which accounts for 70% of our total power usage,” Fletcher said, adding that refrigerant selection plays a major role in meeting Americold’s emissions reduction goals.
• “Americold does not have a ‘one-size-fits-all’ or ideal refrigerant,” Fletcher said. For each project, the company examines multiple refrigerant solutions, considering factors such as climate, capital costs, design constraints, flexibility for future modifications and water and power consumption.

New construction: Fletcher highlighted two new Americold projects using technologies he said were not available five or ten years ago: a 600TR (2.1MW) low-charge packaged ammonia system in a warehouse in Kansas City, Missouri, and a 240TR (844kW) transcritical CO₂ rack in a facility in Saint John, New Brunswick (Canada).

• The warehouse in Kansas City, completed in June, handles imported and exported goods from Mexico. “With the facility’s 100 truck dock doors and frozen storage for 22,000 frozen pallet positions, the packaged ammonia system provides a good fit,” Fletcher said. “If I were to lose one of the 10 [ammonia] packages, I could still operate this building.”
• The Saint John’s warehouse, with a 2026 completion date, is Americold’s first transcritical CO₂ facility, Fletcher noted. “The single-stage system makes sense for the climate and alleviates the concerns of the nearby community,” he said, adding that the company is still investigating a partner to use the system’s abundant waste heat.

Updating warehouses: Americold plans to retrofit its legacy synthetic systems with transcritical CO₂ racks, according to Fletcher, with a few facilities already undergoing replacements.

• “In an operating warehouse, the form factor of CO₂ allows us to install the rack and then take over parts of the facility room-by-room with the new refrigeration system,” Fletcher said.

Quotable: “In the future, Americold will build facilities with large, central ammonia systems, packaged ammonia systems and transcritical CO₂ systems,” Fletcher said. “The choice will depend on what is the right fit for the site, the design and the customer.”

“Manufacturers are addressing our flexibility and maintenance needs with scalable packaged solutions in multiple sizes.”

Nicholas Fletcher, Senior Manager of Design Engineering at Americold