Refrigerator producers and users have been wrestling with the most suitable way of getting out of CFCs for some time. The options offered by chemical companies producing CFCs are the HCFCs and HFCs. Both of these have their drawbacks. The main HCFCs on offer are ozone depleters, albeit less potent than the CFCs. And most of the HFCs currently available have a high global warming potential.
German companies have led the way into other options. Three announced this spring that they will be producing domestic refrigerators using propane/butane mixtures as refrigerants (ENDS Report 218, p 2 ).
The German retailer Edeka has now announced plans for a new "Tesco-sized" supermarket with a refrigeration system using ammonia as the primary coolant. The ammonia will be isolated in a unit outside the supermarket to minimise risks to shoppers and staff in the event of a leak, while the bulk of the refrigerant circuit will contain a propylene glycol/water mixture. The system is more expensive to install than other options but is claimed to have an energy efficiency comparable to or better than that offered by systems run on HCFC-22, the alternative of choice until now.
The feasibility of such systems has been publicly debated for some time (ENDS Report 213, pp 11-12 ). British supermarkets initially dismissed the use of ammonia as too dangerous, then said it was not sufficiently energy efficient - and are now questioning its suitability for large stores.
Most British retailers have opted for HCFC-22 as a stop-gap replacement for CFCs in intermediate-temperature open food cabinets and in low-temperature freezers. Some have plumped for HFC-134a as a long-term substitute for new food cabinets, but the chemical's thermodynamic properties do not allow it to be used for freezers. New blends of the HFCs are being developed that will possess suitable characteristics for lowtemperature refrigeration.
Sainsbury's has now announced that from November it will cease to equip its new stores with HCFC-based refrigerator systems, reversing a policy it has had since 1989. It will also stop using HCFCs in the insulation foam of refrigerator cabinets, opting instead for pentane-blown foam.The company intends to switch to HFC-134a in intermediate-temperature food cabinets, and to HFC blends for freezers.
Announcing the new policy, Sainsbury's Development Director Ian Coull said that the company has "always regarded HCFCs as strictly a transitional substance and I am pleased that following extensive testing with our suppliers on new alternatives, we can complete this move away from HCFCs so far ahead of the international deadline."
Greenpeace, which has been campaigning to get Sainsbury's out of HCFCs, said that the firm's move proved that the current international controls on the chemicals are absurdly lenient. They group maintains that it is unnecessary to allow the production of large quantities of HCFCs for the rest of the century when a major user has been able to devise more permanent and acceptable solutions if pushed.
Greenpeace has also been pressing Sainsbury's not to switch to HFCs because of their impact on global warming. The company has appointed a consultancy to look into the use of ammonia world-wide, but says that there are no examples of its use in stores on the scale of its own supermarkets.
In the meantime, rumours continue to abound about Tesco's plans for introducing CFC and HCFC substitutes. The latest is that the company is planning to build a store using a secondary coolant system based on ammonia next year. However, despite promising last October that an announcement was imminent, Tesco has remained conspicuously silent on the issue, seemingly content to let Sainsbury's lead the debate.