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Overwaitea cuts greenhouse gases with CO2 refrigeration

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It's part of the supermarket magic that keeps ice cream frozen and chicken breasts chilled. But refrigerant is not something grocery shoppers think about. Even when it leaks.

"All refrigeration systems will leak eventually," says Wayne Meger, energy manager of the Overwaitea Food Group (OFG) which operates grocery stores under the banners of Overwaitea Foods, Save-On-Foods, Price Smart Foods, Coopers Foods, Urban Fare and Bulkley Valley Wholesale. Meger says a conservative estimate of the annual leak rate is 10% per year, while the U.S. Environmental Protection Agency claims 23.5% to be the industry average. Depending what type of refrigerant gas is used, that can be bad news for climate change.

"Most refrigerants have a very high Global Warming Potential (GWP)," says Meger. "Releasing one pound of our typical refrigerant is the equivalent of releasing 3,900 pounds of carbon dioxide."

As refrigeration technology evolved over the past 100 years, synthetic gases were developed with properties that make them desirable for refrigeration, such as the ability to function at lower pressures. But now that their contribution to climate change is understood, it's time to innovate again.

Energy leader continues to lead

OFG has already embraced energy efficiency, winning a Power Smart Excellence award in 2008 and being recognized for Power Smart Leadership Excellence in 2010. Its sustainability commitment includes zero waste and progress towards 100% renewable energy. Since 2003, the company has reduced energy consumption significantly, on track for their target of 25% reduction by 2014.

That commitment is why OFG has installed an alternative refrigeration system in five of its stores — with a self-imposed mandate to consider the system for any store requiring an overhaul. The system uses carbon dioxide as the refrigerant — a simple, but not yet mainstream — solution.

"CO2 was used in the early 1900s," says Meger. "It's a natural refrigerant; it's created as a by-product of many industrial processes. When used as a refrigerant it has no impact to the environment whereas any of the synthetic refrigerants all have high global warming potential. It's much cheaper to buy as well."

Meger says the drawback with CO2 systems is that they require much higher pressure than other refrigerants. There are certain limitations because of the high pressure and the piping required, he explains, and because of the safety systems that have to be put in place. While Meger says OFG is one of the first in North America to implement CO2-only systems, in Europe, they've been in use for a decade.

Greenhouse gas results

It's making a difference. "Based on a 10% leak rate, we'll be reducing our carbon footprint by 400 tonnes annually," says Meger. That's the same reduction in greenhouse gas production as removing 78 cars from the road, permanently.

Meger says there are some limitations to implementing CO2 refrigeration in all OFG stores. Since the system is less well known, at present the company can only consider it in locations where there are enough knowledgeable refrigeration technicians. Replacement parts and the right grade of CO2 gas need to be easy to source. But Meger says international protocols are likely to phase out the use of the worst refrigerants within 10-15 years, so investing in change now makes sense.

"We're going one step at a time, testing and working out bugs as we go," he says. "There's a cost premium right now, but we expect the costs of components and installation will come down over time. I think any business that is looking to become more green and has refrigeration systems would be interested in this."