Keeping products cool can be costly. For some supermarkets it's their largest single energy expense, so using efficient cooling methods can have a strong effect on the bottom line.
Complicating this process, however, is the imminent banning of some commonly used coolants on environmental grounds. Retailers are taking numerous paths to reach the common goal of cost and energy efficiency.
Although chlorofluorocarbon production has been banned and use of CFCs is being phased out, and production of hydrochlorofluorocarbons is scheduled to be banned in the United States in 2020, some retailers do not see a need to rush into an ozone-friendly hydrofluorocarbon system. Other retailers are skipping HCFC systems entirely and moving right to HFCs.
In addition, a small number of retailers are experimenting with secondary loop systems and natural coolants such as ammonia and carbon dioxide, which offer partial alternatives to traditional coolants.
With a cushion of time before production of HCFCs are banned in the United States and CFCs are phased out, retailers such as H.E. Butt Grocery Co., San Antonio, are taking this opportunity to see what's both cost efficient and effective for them.
The retailer is not going to jump into using HFCs, said Gary Arthur, corporate refrigeration maintenance supervisor at H-E-B. "[HFC] doesn't hurt the ozone but it can have an effect on global warming," he said.
In the meantime, H-E-B has been able to cut refrigeration costs through the use of distributed systems, Arthur told SN.
About two years ago, following the retailer's formation of a committee to address refrigeration issues, H-E-B decided to implement distributed systems in 25 of its 304 supermarkets.
The committee looked at initial and life-cycle costs and then tested several systems, Arthur noted.
Distributed systems work similarly to an electric company's substation. They are located throughout the supermarket and monitor refrigeration, rather than having one or two large mechanical rooms located in the back of the store or on the roof.
With the systems in place for about two years, Arthur said the retailer has been able to cut refrigeration costs by about $10,000 per year per store at the 25 locations.
"The distributed system is H-E-B's new philosophy," Arthur said. The retailer is placing the system in all new stores, as well as trying to retrofit some of the older ones.
With regard to refrigerants, Arthur said that H-E-B is currently using R22, an HCFC, for air conditioning. "You can't beat R22 for air conditioning," he said, adding that it's cost effective and efficient, but cannot be used effectively for low-temperature cooling.
"We had a lot of problems with R22 on low temperature," he told SN. In addition, H-E-B still has a few stores using CFC refrigerants. Because CFC production has ceased, prices for the coolant are rising as it becomes scarce.
One California retailer, who said refrigeration represents 45% of its yearly energy expense, has decided to go head first into HFC technology.
Raley's Supermarkets & Drug Centers, West Sacramento, Calif., currently has 51 of its 116 stores using the HFC 404A, with most of the other locations still using the HCFC R22. Twelve recently acquired Nob Hill stores are using CFCs to keep cool.
"We're converting to [the HFC] 404A," said Edward Estberg, director of facilities at Raley's. He added that the CFC stores will be changed to HFCs as they are scheduled for remodeling.
Raley's has also simplified its piping system to reduce leakage. Leakage of newer refrigerants can be costly, about five times more expensive than with traditional CFCs, an industry source told SN.
The retailer's piping system used to have 30 sets of lines running through a store and resulted in significant leakage. The new "single-pipe system" consists of four sets of lines and is sealed with a high-quality sweat or welded joint, Estberg told SN.
He added that most leaks occur at areas such as valve fittings, "wherever anything can come loose." Over the last three years, Raley's has seen store refrigerant leakage drop from 30% of the charge per year to 7% annually.
According to Estberg, the HFC system works for Raley's. It is controlled from a central location in the store, which represents a slightly different philosophy than H-E-B's.
Raley's is not looking into secondary loop systems or natural alternatives. Estberg said that secondary systems can result in a cost increase due to the system's additional heat-transfer requirements.
"Our emphasis is on high-quality installation, reduced leakage and less compressor wear," Estberg said.
Kmart, Troy, Mich., agreed that installation and design are key to improving refrigeration systems.
"It all starts with design," said Tony Papagna, manager of refrigeration systems design and installation for Kmart.
Super Kmart is currently using secondary loop systems in six stores for medium-temperature cooling, said Papagna, adding that about 100 stores are using HCFCs.
Of the six stores, two have been using the secondary system for two years and four have been added over the last year. Papagna noted that new stores will also use the secondary system, which uses glycol as its refrigerant.
Like Raley's, Kmart has also "simplified its piping system," Papagna told SN.
Papagna, who has been working on secondary systems for several years, told SN that Kmart is researching the possibilities of using secondary systems for low-temperature cooling.
To date, the secondary loop system has not cost "more or less" than traditional refrigeration techniques, he added. "It's no different than a refrigeration system," said Papagna.
What has fueled this movement to alternative refrigeration systems and their coolants? The reason is twofold, according to a refrigeration expert.
"One is the Food and Drug Administration's drop in temperature guidelines for refrigerated cases," said Wilbert (Will) Stoecker, a refrigeration/coolant research scientist for 42 years and professor emeritus at the University of Illinois.
According to Stoecker, the FDA guidelines require that cases be maintained at 41 degrees Fahrenheit instead of 45 degrees Fahrenheit. He also warned that bacteria such as those that cause botulism can still exist even at these low temperatures.
A second concern that has led to the increase in new refrigeration methods is the global-warming and ozone-depleting effect some refrigerants are said to have on the atmosphere.
To combat this environmental issue, some retailers, mostly in Europe, are experimenting with "natural" refrigeration/coolant systems.
Some of these alternatives include using water, air, ammonia and carbon dioxide in secondary loop systems. But currently carbon dioxide and ammonia are not widely used in the United States.
Ammonia is being used quite often in Europe, noted Stoecker. It is used outside the supermarket as a chiller; the ammonia cools antifreeze because it cannot be used in occupied spaces, and then the antifreeze is piped through the cases in the store.
Carbon dioxide's use as a low-temperature coolant is still somewhat new to refrigeration. Stoecker said that one drawback is that carbon dioxide requires high pressure and must be condensed by a medium-temperature system and then pumped in as a liquid.
The advantage of the carbon dioxide is that in case of a leak there is "virtually no problem," Stoecker said. "It's nontoxic."
One refrigeration technology obstacle that has yet to be resolved is finding a coolant material that has both low viscosity and high specific heat, according to Stoecker. "It's been a very active field of development," he added.