In July 2013, Hannaford Supermarkets installed the first transcritical CO2 booster system in a U.S. supermarket, at a store in Turner, Maine. After that, the 189-store New England chain, a division of Ahold Delhaize, opened a second transcritical store in North Berwick, Maine, in 2015. This year it completed a transcritical retrofit in an existing store in Raymond, N.H. – among the first such retrofits in the U.S.

At the Food Marketing Institute Energy & Store Development Conference in Orlando, Fla., last month, talked to Harrison Horning, Hannaford’s director of energy & facility services, about the transcritical stores and his plans for this technology.

R744: How are the first two transcritical systems functioning and how do they compare with your more traditional systems?

Harrison Horning: They’ve been working well. For the first one, we still contract with the supplier for some monitoring service so we have an ongoing expense there. But, with their 24/7 oversight, we feel that we’re covered. The second one is handled by our own team, and it’s a small store – 20,000-sq-ft. I’d say its maintenance and refrigerant replacement expenses are comparable to any other store of that size and vintage.

R744: What about energy-wise?

HH: Energy-wise they’re probably both around 5% higher energy use than what we might have had with our standard system. But our standard prototype is a premium system that is optimized for our climate so we never really expected to do better than that. We wanted to at least get our feet wet with transcritical CO2, and then be able to add features like parallel compression, possibly an adiabatic gas cooler, possibly ejectors and direct heat reclaim – the new features that we would expect to improve performance or bring it to par or maybe even better than our old standard.

“Across the industry there are thousands of existing stores that have opportunities to use more natural refrigerants.”

Harrison Horning, director of energy and facilities, Hannaford

R744: Are those additional features something you might add to the original stores? Or do you feel that the energy is sufficient?

HH: No, the energy is close enough, and GHG-wise we’re way ahead. I think those features you would purchase with a new system are very difficult to retrofit. You could retrofit an adiabatic gas cooler, but you wouldn’t want to do that until the old one was at the end of its life. The third system we did in the existing store in New Hampshire does have parallel compression and direct heat reclaim, so we’re going to learn about the benefits of those features and we’ll expect the performance to be better than those earlier systems. And in the heating season we’ll be able to see if we are burning less propane to heat the store because we have better heat reclaim. We’re expecting some good results

R744: Will you be doing more retrofits in existing stores with transcritical?

HH: We actually found three stores that are due for remodel that met our criteria to replace their refrigeration system with transcritical CO2. But we decided that we would just do one and get some experience with it first. Now our task it to get some feedback about how it’s working by the end of 2017. This is our criteria for a retrofit: Is all the equipment at end of life? Is the piping at end of life? Do we have space where we can conveniently add these new transcritical racks? If so, that store would be a candidate and we could start the process. We’re looking forward to that because the reality is we’re not building a lot of new stores, and across the industry there are thousands of existing stores that have opportunities to use more natural refrigerants.

R744: And when you do build new stores, you plan to use transcritical systems?

HH: Yes, right now that’s the new standard. We may pilot some other things like propane cases or maybe medium-temp glycol, but if we’re just doing a standard new store today, I’d say it’s transcritical CO2. And we would expect the cost premium to be pretty minimal and something that we would get approval for.

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