Producing clean refrigeration
Refrigeration is essential for the fresh produce and frozen food sections in supermarkets and hypermarkets. But the refrigerants used have a major impact on the environment (they are greenhouse gases and have a high carbon footprint). Carrefour has started using a breakthrough technology that involves CO2 – a natural gas that has little or no impact on the ozone layer and does not contribute to the greenhouse effect.
The challenge with which Carrefour is faced is to find a means of ensuring that the cold chain is not broken, maintaining customers’ comfort levels in the fresh produce sections and – most importantly – using a refrigerant that does not damage the ozone layer and which has little or no effect on the greenhouse effect. Being able to generate low temperatures of between -18°C and 4°C and maintain them is fundamental in the agri-food sector – as well as in the food distribution industry and in stores. The cold chain is what guarantees food safety and the quality of the products sold in Carrefour stores.
Maintaining the cold chain involves using refrigerants in the refrigeration production systems (freezers and refrigerators). Refrigeration production is therefore required along the whole length of the agri-food chain – from upstream right up to the retail outlet. Until now, the most frequently used chemicals have been HFCs (hydrogen fluorocarbons), HCFCs (hydrochlorofluorocarbons) and CFCs (chlorofluorocarbons). Together, it is believed that these chemicals account for a third of all greenhouse gas emissions. Successive rafts of European legislation have sought to limit their use or even ban them altogether because of the major impact that they have on the environment.
There is an alternative: transcritical CO2 units can be used in the fresh produce and frozen food sections. CO2 is a compound that is naturally present in the atmosphere. At normal temperature and pressure, it is a colourless, odourless gas. When it is heated to above its critical temperature – 31.1°C (hence the term “transcritical”) – it starts to exhibit refrigerant properties. There are many environmental benefits associated with CO2 refrigeration systems:
. A very low carbon footprint (CO2 has a warming potential that is 450 to 9000 times lower than gases in the HFC family over 20 years).
. It is non-flammable, non-corrosive, chemically inert, non-toxic and so non-hazardous for store personnel.
. It is more energy-efficient and so less electricity is required (generating savings of between 10% and 20%).
. Systems are more airtight and so less gas is released into the atmosphere.
170 stores in 7 different countries have been fitted with them. Their energy performance has been tested in hot climates (Valencia in southern Spain, for example) and has been found to be very convincing. Overall, these energy savings contribute to Carrefour’s energy savings plan and have helped it get its ISO 50,001 certification (it is the first retailer in France to receive this certification). Transcritical CO2 therefore looks like an area for future exploration for refrigeration. A breakthrough technology that has been tested and approved by Carrefour.
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