On top of the usual "spills in aisle five," grocery stores have another mess they're hoping to clean up: greenhouse gas leaks.

U.S. EPA announced yesterday that its partnership to cut greenhouse gas emissions from grocery stores has reached 50 states. The partnership, called GreenChill, now has 7,000 members, about a fifth of all supermarkets in the United States.

Much of their carbon footprint comes from the electricity that powers their lights, soda fountains, meat slicers and other equipment. But there's a subtler, sometimes bigger source of greenhouse gases: the massive refrigerators and the systems that keep them frosty.

Grocery stores use a network of pipes and pumps to get coolant to the refrigerators. The coolants are typically greenhouse gases that, if they escape, have a global warming effect hundreds or thousands of times greater than carbon dioxide's.

"If you have a lot of piping, if you have a lot of joints, the probability of leaking is greater," said Karim Amrane, vice president of regulatory and research at the Air-Conditioning, Heating and Refrigeration Institute, a trade group representing equipment manufacturers.

EPA doesn't directly regulate these emissions, so it set up GreenChill in 2007 to encourage supermarkets to act on the issue voluntarily. The agency has offered Silver, Gold and Platinum awards to grocery stores that prevent the gases from seeping.

One Platinum awardee, Star Market in Newton, Mass., used to need 4,000 pounds of refrigerant; now it needs 275. According to the manufacturers of the new equipment, just a pound of this refrigerant has the same effect as 3,800 pounds of CO2.

Big opportunities for reductions
On top of that, the store believes it has plugged up many of the common leaks. Where it would normally store refrigerant in 2,000-pound cisterns, now it uses dozens of 11-pound cells. If any of them springs a leak, the total emissions are far smaller.

A store doesn't have to be state-of-the-art, like Star Market, to benefit the climate. If every grocery store in the United States were just at the level of the average GreenChill member, EPA claims, it would save the equivalent of 22 million tons of CO2 a year.

That's roughly the annual emissions of 4.3 million cars. It would also save the stores $100 million -- cash they wouldn't have to pay for replacing their elusive coolants.

Cindy Newberg, a branch chief at EPA's Stratospheric Protection Division, said GreenChill's 7,000 members will benchmark their refrigerants to see how much they're losing and where. The companies can also share information about best practices.

Greenpeace wants to take the issue even further. The group yesterday won a Harvard University award for pushing green refrigeration with major world retailers, including Safeway, Wal-Mart and Kroger.

Debate over 'natural refrigerants'
In November, 400 such retailers committed to stop using hydrofluorocarbons -- coolants that affect the climate far more than CO2 -- by 2015.

HFCs, as they're known, are the main refrigerant in use today. But Amy Larkin, a solutions director for Greenpeace, said Greenpeace has long been wary of them.

"When HFCs were introduced in the early 1990s, Greenpeace said, 'Whoa. This is a horrible substitution for CFCs, because they may not carve a hole in the ozone, but they will kill us with global warming,'" she said.

Larkin and these companies believe the technology for "natural refrigerants," such as ammonia, CO2 and even some fossil fuels, isn't far away. These coolants have far weaker effects on the climate than HFCs.

Amrane, of AHRI, the air-conditioning trade group, was more skeptical.

He said there are coolants with low global warming effects, but even if they keep the food cold, they may pose safety hazards. "There's always a trade-off," he said.

A tiny bit of propane or butane in a household refrigerator poses little risk, he said, but a large system, such as the one in a grocery store, is a different beast. "From a safety standpoint, having hundreds of pounds of propane might not be a safe thing to have," he said.

EPA is still evaluating whether the compromise on the federal budget for 2011 will affect the GreenChill program.

Reprinted from Climatewire with permission from Environment & Energy Publishing, LLC. www.eenews.net, 202-628-6500