Sprouts CO2 Booster System Refrigeration
Figure 1 - CO2 Booster System Rack
Supermarkets likes Sprouts have recognized that the need to move toward nonHFC (hydrofluorocarbon) refrigerants has become increasingly apparent over recent
years. The most effective key to accomplishing this has been through the use of carbon
dioxide (CO2) as an alternative.
A number of reasons have factored into the move away from HFCs. Foremost
among these are the environmental concerns that lead initially to international
agreements (i.e., Montreal and Kyoto Protocols) and then to regulations such as those in
the Clean Air Act. The impact of these regulatory pressures on supermarkets has added
economic justifications to the move away from traditional refrigerants.
In one of their newest store located in Dunwoody, Georgia, Sprouts is employing
an advanced technology, booster system that uses CO2 (R-744) instead of HFCs. This
first application of its kind to more temperate regions of North America (the approach
has been used successfully in northern climates including across Canada, the upper mid-
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west and New York) is made possible by an innovative use of a naturally occurring
cooling process called adiabatic condensing. Long used in data centers and other types
of facilities, the same process that creates cloud formations in the atmosphere, works
off the flow of warm air through a particular type of water-cooled condenser.
This type of condenser works by pumping water through a particular section of it
when the outside temperature reaches above a certain point. As the outside air passes
through condenser, the water absorbs heat. This in turn, effectively lowers the
temperature needed to cool and, under most conditions, condense the C02 in the
system. The difference between this and other types of water-cooled condensers is that
in this type the coils in the condenser stay dry which means less maintenance and less
water usage. There is, however, essentially no difference between these the dry gas
cooler typically used with booster systems in cooler climates except that with an
adiabatic condenser the system is able to use what is called a lower “dry bulb”
temperature to cool the CO2. The advantage of this is that it allows the CO2 to continue
condensing in warmer conditions longer than it would otherwise do with a dry gas
cooler and lower condensing temperature means lowers energy usage.
Figure 2 - Adiabatic Condenser
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Overall, the technology reduces the carbon footprint of the store’s refrigeration
to near zero. In fact, the use of CO2 in the system amounts to the equivalent over 10
years of:

Removing 1, 182,750 cars from being driven

Eliminating 733,732,403 gallons of gas from being consumed

Growing 165,727,478 trees
For companies like Sprouts that are focused on sustainability, responsible
corporate citizenship, and smaller carbon footprints, the CO2 booster system
technology used in their new Dunwoody, Georgia store makes perfect sense.
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