“Refrigeration makes up roughly one-third of our total energy consumption, and we’re committed to natural refrigerants because they reduce our energy consumption and direct environmental footprint through potential emissions from refrigerant leaks,” said Coffin.

But figuring out a natural solution for their self-contained cases presented a challenge for the retailer. In 2013, when WFM sought to open its first “natural store” in Brooklyn, NY, with zero synthetic refrigerants on premises, they went on the hunt for a more efficient, self-contained natural refrigerant option.

“We didn’t want to just drop a bunch of inefficient, synthetic refrigerant cases on our sales floors, because they would negatively impact our energy usage and go against our sustainability efforts, especially in stores where we are utilizing all-natural refrigerants,” Coffin explained.

Although R-290 was becoming the refrigerant of choice for retailers looking for a natural, self-contained case option, at the time there were very few U.S. refrigeration equipment manufacturers that offered R-290 units. But AHT Cooling Systems USA was on this short list. Howell Feig, national sales manager for AHT, said that developing R-290 products for the European market enabled the company to help early adopters in the U.S.

“We had been manufacturing bunker-style cases for our European customers since 2002, and around 2010 some of our environmentally-driven U.S. customers started asking for self-contained, R-290 based equipment,” Feig said.

Since the 2013 Brooklyn installation, Coffin said that R-290 self-contained cases have been deployed across the company’s entire network of stores. He estimated that 50 to 60 stores a year are installing new cases.

Both Feig and Coffin believe that the U.S. food retail industry is slowly shifting toward R-290 use in self-contained cases. Feig explained that early adopters like Whole Foods Market have served as a proof of concept for other retailers. As a result, adoption has increased to the point where AHT will transition its entire equipment platform to R-290.

WFM’s sustainability mission has led to experimentation with innovative system architectures. Coffin explained that there’s no “one-size-fits-all” solution and every store is evaluated individually based on the facility’s characteristics and climate impacts.

In 2016, the company opened a facility in Santa Clara, CA, which features one of the company’s most environmentally-friendly refrigeration systems. The system is based on an R-290/CO₂ cascade architecture that reduces the environmental impacts of refrigerants to near-zero, while greatly improving energy efficiency.

This system uses R-290 to condense CO₂, which is then distributed to connected cases throughout the store. CO₂’s high heat-carrying properties reduce both the amount of refrigerant needed and the energy required to run the refrigeration system. Simultaneously, a heat reclaim system captures the heat generated by the system, and uses it to preheat the store’s hot water supply and supplement space heating — a strategy that enables the store to greatly reduce the amount of natural gas burned to heat water.

“The system uses the least possible amount of the most climate-friendly refrigerants while reducing the energy it takes to operate it and re-using the heat it generates,” said Coffin. The Santa Clara store also features 10 of AHT’s self-contained cases for product showcases on the floor.

From a safety and servicing perspective, Coffin believes that the novelty of R-290 in the U.S. brings with it a degree of apprehension about its impacts to service technicians and endusers. While safety protocols are mandatory with the use of the class A3 (flammable) refrigerant, Coffin feels that the perceived risks are often not proportionate to the actual risks.

“The reality is we use natural gas and propane to heat and cook for residential and commercial purposes all the time in this country. It’s simply a matter of educating endusers and technicians about proper safety protocols,” Coffin said. “Plus, self-contained OEMs have done an excellent job of making these systems safe and user-friendly, and training their service technician base.”

Coffin and Feig believe increasing the charge limit of R-290 systems (currently at 150g) would open new opportunities. Coffin said that an increase to 500g would allow R-290 to be used in open-door cases as well as walk-in coolers and freezers. This prospect could potentially even allow for a full-store solution of self-contained R-290 cases, which would be particularly advantageous in smaller urban locations where space constraints prevent the use of centralized racks.

“Increasing the charge limits would enable significant advances in system design and efficiencies,” said Feig.

 Even at the current charge limit, Coffin said that the R-290 cases are a solution they plan on using for many years to come.