Natural Refrigerants: St. Louis-Based Supermarket Chain Opting for Transcritical CO2 Refrigeration
Dierbergs Markets opened its first CO2 store in May and second in August, with plans to continue installing the technology
St. Louis, Missouri-based grocery chain Dierbergs Markets is installing transcritical CO2 (R744) refrigeration systems in new stores as part of a long-term strategy, Ben Rola, the company’s Director of Engineering and Maintenance, told NaturalRefrigerants.com.
In August Dierbergs opened its second CO2-cooled store, a 73,000ft2 (6,780m2) supermarket in St. Charles. Its first CO2-cooled store, a 75,000ft2 (6,970m2) supermarket, opened in University City in May. The company currently operates 29 stores in Missouri and Illinois, primarily in the greater St. Louis area.
“We see CO2 as the future refrigeration for Dierbergs,” Rola said. “Rather than invest in another generation of synthetic refrigerants and potentially face another [regulatory] transition later, we chose to move directly to a proven natural-refrigerant technology with a much lower global-warming impact.”
St. Charles details: The store uses two transcritical CO2 booster systems to provide roughly 1,400MBH (116.7TR/410kW) of medium-temperature capacity and 500MBH (41.7TR/147kW) of low-temperature capacity, according to Rola.
Heat recovery from the CO2 system provides domestic hot water throughout the store via a heat exchanger.
Reclaimed heat also helps heat a section in the back of the store during the winter.
Dierbergs worked with DC Engineering to design the refrigeration system with CO2 equipment manufactured by Hussmann, a Panasonic subsidiary. The local company Jarrell Mechanical Contractors installed it.
The performance: Research indicates that the CO2 system should be energy-neutral over the course of a year, Rola said, with energy savings during Missouri’s cold winter expected to offset the higher energy demand of its warm, humid summers.
The racks use an adiabatic condenser to keep the system from operating in transcritical mode as much as possible, Rola noted.
Going forward: Dierbergs plans to continue installing CO2 refrigeration systems in new stores, according to Rola.
“Although many of the long-term benefits [of CO2] will be realized over time, the system helps position Dierbergs for EPA [the U.S. Environmental Protection Agency] regulatory changes, while reducing the environmental impact associated with conventional refrigerants,” Rola said.
Dierbergs has not yet integrated a store’s HVAC system with its CO2 refrigeration system. However, it is considering that configuration in a future location, Rola said.
Quotable: “We have benefitted from the experience of other retailers and believe our adoption can help show that this technology is achievable for companies with a smaller footprint,” Rola said.
“We have benefitted from the experience of other retailers and believe our adoption can help show that this technology is achievable for companies with a smaller footprint.”
Ben Rola, Director of Engineering and Maintenance at Dierbergs Markets