Getting Cooler

MATTHEW ENIS

The U.S. Environmental Protection Agency's GreenChill Advanced Refrigeration Partnership has continued to attract major new members from the supermarket industry this year. This spring, Hy-Vee and Buehler's became the latest companies that have vowed to reduce refrigerant leaks, adopt green refrigeration technologies and strategies, and require that all of their new and remodeled stores use environmentally friendly refrigerants. In exchange they've been given access to a growing group of 50 companies that shares ideas and best practices for achieving those results.

About 70% of supermarkets in the U.S. currently use direct expansion refrigeration systems to cool display cases and walk-in coolers. The challenge with these traditional units is that they force synthetic HCFC and HFC refrigerants at high pressure through thousands of feet of copper piping throughout a store. HCFC refrigerants are particularly damaging to the atmosphere's ozone layer, and the hundreds of valves and fittings on all that copper piping are one factor that leads to an average emission rate of 15% to 30% for these DX systems, according to EPA estimates.

Several systems have helped retailers significantly curb those emissions. Distributed systems, for example, place multiple small compressors closer to the display cases and coolers they service. The result is less piping than a traditional DX system, a smaller refrigerant charge for the smaller systems, and less pressure and fewer leaks as a result.

Newer technologies include secondary loop systems. These systems are similar to DX systems in that they employ a rooftop condenser and a single set of compressors — which may use traditional refrigerants — in a supermarket's machine room. The difference is that the machine room compressors are used to cool a second, more environmentally-friendly coolant, that is then circulated throughout the supermarket's refrigeration system in a “secondary loop.” There's fewer opportunities for leaks of the more harmful refrigerants, and the secondary fluid can be sent at lower pressure through the secondary loop, making leaks less likely.

Cascade CO2 systems are also attracting growing interest. These systems use naturally occurring carbon dioxide as a primary refrigerant. The challenge there is that concentrated CO2 generates a tremendous amount of pressure when it isn't held at a low temperature. So, similar to the secondary loop systems mentioned above, a separate refrigeration system — typically using ammonia, butane or propane — must be used to cool the CO2. Both systems share a common cascade heat exchanger.

El Segundo, Calif.-based Fresh & Easy Neighborhood Market this month opened a new location in Rosemead, Calif. that became one of the first four supermarkets in the U.S. to use a cascade CO2 system. According to a company release, the system reduces the impact of the store's refrigeration on the ozone layer by 70%, when compared with a conventional supermarket. Also, by using natural refrigerants instead of HCFCs, the system has a 50% lower global warming potential than conventional refrigeration systems. The store was immediately GreenChill certified.

“It's just one of our various efforts on the environmental front,” Fresh & Easy spokesperson Brendan Wonnacott told SN, noting that the company also employs green building design principles in its stores, such as increased insulation, skylights and LED lighting for signs. “The EPA has been a fantastic partner and [GreenChill] is a great program.”

Dennis Curtin, director of public relations for Weis Markets, Sunbury, Pa., also praised the program, noting that since its launch in 2007, GreenChill has helped established standards and criterion for the industry, and has shared research and information on best practices to their retail partners.

Weis last week received an award from GreenChill for Most Improved Emissions Rate, after slashing their refrigerant emissions by 20% in a single year. The company plans to install new, advanced refrigeration systems in three new stores it is currently building in Bellefonte, Forks Township and Spring Township, Pennsylvania.

“The new systems we are using reduce refrigerant charge by 60% which in turn reduces our costs and helps preserve the earth's ozone layer, which in turn impacts global warming,” Curtin said. “These systems use roughly the same amount of energy as a conventional system.”

The new systems are also part of a broader approach to energy reduction and sustainability at Weis. For example, heat generated by refrigerated and frozen cases is used to heat stores during the winter, and to heat hot water used in the stores year-round. The company has installed more efficient lighting systems, and systems that monitor energy usage and help conserve energy during non-peak periods. And, whenever stores are remodeled or expanded, Weis looks for ways to make them more energy efficient “wherever possible,” Curtin said.

“Our sustainability program is an extremely important part of who we are as a company,” he said. “It's part of being a good neighbor in the communities we serve. And, if done successfully, it can help us manage our resources and minimize our environmental impact in a way that benefits our company.”