The Greenpeace campaign has turned the spotlight on a sector which has made little progress in phasing out ozone-depleting substances. In 1986, it used 3,700 tonnes of CFC refrigerants, or just over 5% of total UK consumption. By 1991, the figure had declined by only 450 tonnes, and because most other sectors had achieved larger reductions the retail industry's share of UK consumption had risen to almost 20%. Most of its purchases were used to replace CFC refrigerants which had leaked to the atmosphere.
Meanwhile, the alternative used by many retailers in new or upgraded stores has been HCFC-22, which has a lower ozone depletion potential (ODP) than the CFCs.
A few months ago, Sainsbury's led the way into commercial-scale use of HFC-134a, which does not deplete ozone. The product is suitable as a refrigerant for non-frozen food cabinets, but does not function well at the lower temperatures used in freezers. The company intends to replace all CFCs remaining in its stores with HCFC-22 or ozone-benign refrigerants by the end of 1996, and claims that this policy makes it the world leader in the retail sector.
The claim is derided by Greenpeace, which is campaigning against both HCFC-22 and HFC-134a.
Sainsbury's insists that HCFC-22 is acceptable because it has only 5% of the ODP of the CFCs. Greenpeace says rightly that to leave the matter there is misleading, since ODPs reflect only the long-term impact of chemicals on the ozone layer. During its first ten years in the atmosphere, HCFC-22 will be about 20% as damaging to the ozone layer as the CFCs. This, Greenpeace argues, makes increased use of the chemical unacceptable because it will exacerbate the threat to the ozone layer at just the time ozone depletion is expected to reach a peak due to past and impending releases of CFCs, halons and other substances.
The group is also opposed to the commercialisation of HFC-134a because of its global warming potential. The chemical is more than 3,000 times more powerful than carbon dioxide as a greenhouse gas.
Sainsbury's greeted the new campaign by accusing Greenpeace of making "grossly defamatory and false allegations." By the end of October the temperature had cooled a little, but the retailer was still rejecting the group's request for a high-level meeting to discuss the issues.
The question raised by the campaign is whether there really exists an alternative refrigerant which neither depletes ozone nor enhances global warming, and which also satisfies relevant performance and safety criteria.
An official report published in October concludes that there is not (see below). Prepared by March Consulting, it says that "it has not been possible to identify a simple family of alternatives that offers a reasonable compromise" between environmental, safety and performance requirements. "Instead, there are a somewhat bewildering and steadily increasing range of alternatives that each have certain advantages and disadvantages.'
The principal options available in commercial quantities and with proven refrigeration capabilities are HFC-134a and ammonia.
HFC-134a has similar thermodynamic properties to CFC-12 and has just successfully completed its toxicity testing programme. The compound can be retrofitted into CFC-12 units operating at temperatures as low as -15°C, making it suitable for chilled food cabinets but not freezers. HCFC-22, in contrast, can be used in both applications.
Ammonia has been used in industrial plants such as breweries and cold stores for many decades. Its refrigerant capabilities are beyond question but it is toxic, slightly flammable and explosive. These qualities appear to have persuaded most retailers to shun it. "It is madness to suggest that a modern supermarket might equip with ammonia," a Sainsbury's spokesman commented recently. "Even a mention of an ammonia leak could create wholesale panic in a crowded store."
However, Greenpeace maintains that ammonia is a viable alternative provided precautions are taken. It could, for example, be used in two-stage cooling systems. In these, ammonia is used as a primary refrigerant in a unit remote from a store, and operating in conjunction with a secondary system using a more benign coolant such as glycol or alcohol.
According to one UK refrigerator manufacturer, secondary cooling systems employing ammonia which are suitable for retail stores are about to come on the market.
Tesco is said to be considering this option. Greenpeace says that it was told in a recent meeting with the company that it is about to announce a switch to ammonia-cooled chillers in new stores from 1994. A spokeswoman for the firm confirmed that an announcement on a new ozone-benign refrigeration system is imminent, but would not confirm or deny that it will be ammonia-based.
Greenpeace also contends that retailers could follow the Swedish example in drastically reducing HCFC usage as an interim measure. Since 1984, secondary cooling systems for chillers using HCFC-22 as a primary refrigerant and glycol or alcohol as a secondary coolant have become commonplace in Swedish supermarkets. These employ 60% less HCFC-22 than the systems now being introduced in UK supermarkets.
A major supplier of these systems in Sweden, Electrolux, has also brought to market a two-stage cooling system for freezers which offers 80% reductions in the amount of HCFC-22 consumed.
Electrolux says it has been trying to export secondary cooling systems to other European countries, and expects to sign a contract with a Dutch retail chain soon. German supermarkets are also said to be very keen. But UK retailers have shown little interest. The technology could in principle be used with ammonia as the primary refrigerant.
Several UK refrigerator manufacturers commented that the drawback of secondary cooling systems is the energy efficiency penalty incurred when heat has to be transferred across two sets of heat exchangers rather than one. This, they note, would mean solving the ozone depletion problem at the price of a higher impact on global warming. However, Electrolux maintains that the operating costs of secondary cooling systems are no higher than those of new single-stage HCFC-22 units.
The Greenpeace campaign has undoubtedly alarmed fluorocarbon producers. They argue with some justification that it would take longer to phase out CFCs if HCFC-22 and even HFC-134a came to be regarded as unacceptable options, since the technology and skills needed for a large-scale switch to ammonia are not widely available.
What is causing concern to companies such as ICI and Du Pont is the possible knock-on effect if a major retailer such as Tesco announced a progressive switch to ammonia. They will remember clearly what happened in 1988 soon after Friends of the Earth launched a campaign against the use of CFCs in aerosols. Eight aerosol producers broke ranks and announced a switch to other propellants. The rest of the industry caved in just three months later (ENDS Report 160, pp 3-4).