A shift from ambient to chilled foodstuffs and an increasingly sophisticated range of both fresh and frozen convenience products have caused a boost in refrigerated floor space in supermarkets worldwide. Also food safety issues and quality thinking drive the need and demand for refrigerated shelf space. For full-service supermarkets chilled products have become a key strategic discriminator. But also discount formulas such as Aldi are extending their fresh food departments in order to remain competitive. ‘Fresh’ and to a lesser extent ‘frozen’ have become retail formula brand builders that must be kept in shape.
Elsevier Food International, Vol.9, September 2006 Vincent Hentzepeter

According to a market survey of Frost & Sullivan, supermarkets are looking for the ideal ‘cooling’ solution. In many cases they break the traditional life cycle for replacement of cooling and freezing cabinets. Premature investments in innovative refrigeration systems are part of a strategy to remain successful in the long term. However, not against all costs. Retailers are highly focused on short-term savings as cooling and freezing equipment consume up to 50 per cent of electricity and cause considerable operation and maintenance costs. Not surprisingly increased efficiency is the number one purchase criterion when it comes to selecting a cooling and/or freezing system. Also from an environmental point of view this is often the best choice. Energy efficient and reliable systems have lower emissions of environmental greenhouse gases such as HFCs or even HCFCs (see side-bar) and help to reduce the release of carbon dioxide.

Eco-line
The Kyoto Protocol has put ‘green’ refrigeration systems high on the agenda. The environment has become a key driver when selecting a new supermarket refrigeration system. According to Marion Aiglesberger, marketing manager at refrigerator system supplier Hauser GmbH Kühlmöbel & Kältetechnik, energy-saving systems are definitely on the rise. However, developments cannot be generalised. “For instance, in Germany the subzero and above zero refrigerating sections are placed closely together to minimise energy loss. More generally speaking, closed refrigerated cabinets are increasingly important. This solution entails energy savings of approximately 40 per cent.”
Hauser is one of the suppliers that offers more sustainable refrigeration technology. Aiglesberger about this Eco-line: ”In summer, the waste heat of the refrigeration unit is delivered to ambient air via the condenser. In winter, the waste heat of the refrigeration unit and the heat of the floor are used for heating. Using our system saves heating costs at up to 35 per cent per cent less running costs, a better room climate and a lower room temperature. Furthermore a better degree of efficiency of the refrigeration unit as the waste heat is used in winter, which means less CO²-emissions through oil or gas heatings.”

Emission drop
A growing number of retailers is involved in experiments with ‘green’ cooling technology. Several have implemented systems that significantly reduce energy consumption and emission of typical Kyoto-gases. Potential energy savings can be considerable. The combination of glass-door display refrigeration cabinets along with technical improvements such as small parallel compressors and recovering the reject heat of the cooling equipment for space heating can reduce energy consumption by at least ten per cent. This is proven by an international project of the International Energy Agency in supermarkets in Canada, Denmark, Sweden, the United Kingdom and the United States. Even more impressive was the Total Equivalent Warming Impact (TEWI)-reduction. An emission drop of 60 per cent is possible with low-charge refrigeration systems.

Loss of charge
For the average retailer this is still a thing of the future. Today most supermarkets operate outdated refrigeration systems. Cabinets may look ‘cool’ from a designer point of view, but the equipment that runs backdoor can be highly inefficient. According to DuPont Fluoroproducts, a manufacturer of refrigerants, a mid-sized supermarket in the US is estimated to have 29 km of refrigerant piping and 16,000 connections. This network represents many opportunities for leaks. Not surprisingly large systems show 30 to 50 per cent loss of charge per year. Costs for replenishment are considerable, not to mention the environmental impact. In this respect the investment in more economical, modern refrigerator systems is worth considering. The identification and quantification of these leak resources is the first step to a complete redesign of the refrigerator lay-out. Modern cooling technology with a lower environmental impact is not necessarily more expensive. Costs studies show that installed cost premiums lie in a range from 0 to 35 per cent. Of course this depends strongly on local factors and purchasing agreements. Regardless of costs, the moment a refrigerator system is upgraded refrigerant consumption is decimated, as will the emission of harmful greenhouse gases.

Loblaws
In 2004, the Canadian supermarket chain Loblaws adopted innovative refrigeration technologies in its new store in Repentigny (Quebec). Overall energy consumption was reduced by 23 per cent compared to a conventional system. This is achieved by integrating the refrigeration equipment with the heating, ventilation and air condition system (HVAC) and a design that reduces the synthetic refrigerant charge (HFCs) and optimises the cooling and compression process. Besides environmental benefits the system has eased operation and maintenance and led to more stable food temperatures. As a consequence Loblaws has reported quality and shelf life improvements. The retailer has plans to bring this system, the first of its kind in Canada, on stream at other existing stores.

Natural refrigerants
Quite revolutionary in terms of refrigerant choice is the use of carbon dioxide (CO², see side bar) in supermarket refrigeration systems. The application of this natural fluid gas in combination with ammonia (NH3) has shown a large increase in the industry over the last few years. The two can replace environmentally harmful HFCs and are suitable as supermarket refrigerants. Major advantages are a reduction of greenhouse gas emission by 40 per cent, when compared to HFC-use, and a 10 to 15 per cent lower energy consumption. Moreover, CO² is a totally harmless refrigerant and absolutely safe in use. In spite of proven technology both retailers and installers are sceptical. According to TNO Environment, Energy and Process Innovation (TNO-MEP), a Dutch consultant firm, the benefits seem to be overshadowed by fear of an unfamiliar system with higher installation costs. However, stimulated by governmental subsidies the first supermarket refrigeration system in the Netherlands with only natural refrigerants has been established. In March 2004, a store of the C1000-chain in Bunschoten introduced a so-called NH³/CO²-cascade system. NH³ is applied as a primary refrigerant to ‘cool’ two in-store circuits for cooling and freezing, which is an innovative combination for supermarket refrigeration. Most experiments with CO² in supermarkets in Europe have been restricted to CO² in the freezing section.

Danish project
In Denmark too, new systems with natural refrigerants are being developed and tested. A tax on HFCs in commercial installations and a proposed future ban has motivated retailers to look for alternatives. In 2000 the first pilot of a cascade system based on propane and CO2 in a small supermarket proved successful and encouraged COOP Denmark FDB to start a refrigeration project with the Danish Technological Institute (DTI). In July 2001, the newest store of the Fakta discount chain in Beder obtained a similar system, which has since been rolled out to other new stores. Energy consumption decreased by approximately five per cent compared to comparable stores with conventional systems. Is Denmark paving the way to green refrigeration for supermarkets? Possibly. DTI states that investments in CO2-systems are likely to decrease once more retailers decide to switch. The initial price premium of 20 per cent will soon go down to ten per cent and evaporate to practically zero in the long run.

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Refrigerants: red or green?
Over the last twenty years Hydrofluorcarbons (HFCs) have substituted the ozone depleting chlorofluorocarbons (CFCs) in refrigeration for their lower global warming potential. Still HFCs are powerful greenhouse gases when compared to fluids such as ammonia (NH³) or carbon dioxide (CO²). The combination of the natural refrigerant CO² with, for example, NH3 or propane is a new development and currently practiced in several (European) supermarkets.