ODS are listed by the Montreal Protocol as specific chemicals or 'controlled substances' to be phased out within specified deadlines. Chlorofluorocarbons (CFCs), chemicals containing chlorine, bromine, and fluorine, head this list as the substances that need to be controlled most urgently. Currently 15 CFCs, 3 halons, 34 hydrobromofluoro¬carbons (HBFCs), 40 hydrochlorofluoro¬carbons (HCFCs), carbon tetrachloride, methyl chloroform, and methyl bromide make up this list of controlled substances. CFCs are stable, non-toxic, and easy to store chemicals that have been extensively used since the 1930s in refrigerators, aerosols, air conditioning, and foam blowing. CFC-11 and CFC-12 are the most widely used chlorofluorocarbons. Halons, chemicals consisting of fluorine, and carbon, are used mainly in fire extinguishers and are ten times stronger ozone destroyers than the most potent CFCs.
HCFCs, which are increasingly being used as short-term substitutes for CFCs, destroy ozone at a much slower rate than CFCs but do have high global warming potential. Carbon tetrachloride is used as a cleaner and in the production of CFCs. Similarly, methyl bromide, which has a significant ODP, is used mainly as an agricultural pesticide and fumigant. Methyl chloroform is popular as a solvent and blowing agent and has an ODP about one-tenth that of CFC-11.
The need to phase out these chemicals is obvious, but since they are so useful to the global economy, only the availability of proper ozone-friendly substitutes will allow countries to realise phase-out targets. Countries had started working towards the phase-out of some of the most damaging ODS even before substitutes became available. Intense research over the past few years has today yielded a
large number of substitute chemicals and technologies to effectively replace CFCs, halons, CTC, and methyl chloroform. These substitutes range from natural substances like water and carbon dioxide, and simple chemicals like ammonia and isobutane, to blends of complex chemical compounds like hydrofluorocarbons (HFCs).
There is no one perfect substitute for a certain ODS. The choice of the substitute depends on the purpose behind the use of an ODS. For instance, HFC 134a might be a perfect substitute for CFC-ll in aerosols, but methylene chloride is a much better choice to replace CFC-ll in the foam sector. Similarly, the choice of alternative substances is not without problems. Some very effective substitutes for ODS are not widely used because of problems like high global warming potential, health hazards, high costs of installation, and incompatibility with existing equipment.
In some cases, it might be possible to use a new technology that entirely eliminates the need of an ODS. For instance, the use of fire-resistant materials can greatly reduce the instances of accidental fire and therefore of the use of halons from fire extinguishers. Similarly, the use of mechanical pumps,
dual compartments, and roll on/stick systems has removed the need of propellants in aerosols.
Yellow fire extinguishers contain halons, which deplete the ozone layer, while red fire extinguishers use ozone friendly chemicals. Alternative, affordable chemicals exist for all ozone-damaging chemicals, and these substitutes don't harm the ozone layer.
In spite of these problems, the process of substituti ng all ozone depleti ng substances with ozone friendly chemicals or technology is already in full swing throughoutthe world, well before the required deadlines. This is mainly because countries will soon enforce regulations to control ODS consumption, and ODS containing equipment and chemicals will not only be costly but also increasingly difficult to find as time passes on. The common strategy among factories has been to continue using existing ODS containing equipment until the end of their service lives before proceeding with retrofitting or replacement plans. CFCs from obsolete equipment are then recovered and recycled. This is economically more favourable, but might prove to be harmful in case of significant leakage of CFCs into the atmosphere.
Today, alternative substances are also manufactured in developing countries like India, China, and Brazil, and distributed worldwide. The substitutes have proved to be particularly important in electronics. In the fire fighting sector, halons are now used only in critical areas like control rooms and aircrafts. Hydrocarbons and hydrofluorocarbons (HFCs), which have zero ODP (HFCs, however, do have significant GWP), have proved to be effective long-term substitutes. In many cases, the use of substitute substances has led to greater efficiency. And as more and more such substitutes are discovered, manufactured, and made accessible, instances of cost-effective replacements of ODS in all parts of the world wi II conti n ue to grow. If the cu rrent situation is anything to go by, it would be safe to say that alternative substances and technologies available today should have no problems in replacing existing ODS, without any noticeable effect on the global economy.
Products using substances that have zero or negligible ODP contain various kinds of labels such as 'CFCfree' and 'ozone friendly' so that consumers can make their choice accordingly. Even when such labels are not used, it is possible to tell most of the time whether a product contains ODS or not. In case of fire extinguishers, for example, the thumb rule that almost always works is that yellow cylinders contain halons, which have very high ODS, whereas red cylinders use ozone friendly chemicals. In addition, such equipment and appliances almost always contain labels listing the chemicals they use, which is the most reliable source of information in determining whether an appliance is really ozone friendly.
These chemicals can be identified in three maJor ways:
• Chemical name, such as 1,1,1trichlorofluoroethane, which is almost never used on labels
• Trade name, such as FREON™
• Refrigerant code, such as CFC-113 or R13, which is the most commonly used form of identification. The American Society of Heating, Refrigerating and Airconditioning Engineers (ASH RAE) established refrigeration nomenclature (codes beginning with R, such as R-500 and R-600a).
Tables in the Annex of this booklet list the refrigerant codes and chemical names of the most common refrigerants and their key substitutes, along with their ozone depleting potential (ODP).
Welcomgroup Park Sheraton Hotel and Towers in Madras, India used HCFcn based chiller plants to operate eight cold storage and freezer units. Following frequent refrigerant leakages, mechanical breakdowns, difficulty in obtaining parts, inadequate capacity, and excessive energy consumption, the hotel decided to replace
all the equipment. The eight cold storage and freezer units were replaced with 11 new
units based on R-404A (which is a blend of HFCs with zero ODP). Although the total cost of this replacement was US$ 200,000, the hotel now saves almost US$40,OOO every year due to energy efficiency and reduced food spoilage. In this way, the hotel expects to recover the cost of installation in five years. Following the success of this replacement, the hotel has also replaced its CFC-12 mini bars with vapour absorption models, which consume 34% less energy than the CFC system they replaced.
The Iran Meat Organisation's (IMO) Ziaran Meat Complex, needing a major update of its capacity, decided to shift from the existing chlorofluorocarbons to ammonia, which has zero ODP as well as very low global warming impact. Accordingly, York Refrigeration Global Contracting supplied fully assembled and tested blast-freezing modules, complete with ammonia charge and ready to operate on the day of delivery, causing minimum disruption to production. Since the two units were installed outside the main building, there were no safety concerns regarding the gas being released within buildings. Although the purchase price per kW capacity of ammonia was higher than equivalent HCFC plants, its efficiency made it perfect for a long-term investment business like the Meat Complex. The improved technology has already led to 25-40% energy savings, resulting in significant running cost savings.
Most ozone-friendly appliances are labeled 'CFC-free' to enable consumers to tell the
Countries of the world ha ve made a legal commitment to phaseout using all main types of ozone-damaging chemicals through the Montreal Protocol. Industrialised countries have already met these targets, and developing countries have time till 2010.
2002 Comsumption Data Reported Under Article 7
To attract attention of NQUs, the following table has been prepared by CAP to highlight the compliance status The colours of traffic signals are used to highlight the status on compliance.
Many Solutions to the Same Problem
CFC-12 finds its greatest appl ication in the refrigeration and air-conditioning industry. Over the past few years, three substances have emerged as replacements for CFC-12 in domestic refrigerators and small capacity commercial refrigeration appliance. HFC-134a has zero ozone depletion potential but a relatively high global warming potential. Its capacity, similar to CFC-12 at high temperatures, goes lower than CFC-12 at temperatures below -10°e. Although it is nonflammable, nontoxic, and matches the capacities and operating conditions of CFC-12, its use in refrigeration is not without a few problems-it is sensitive to contamination, does not mix with mineral oils used with CFCs, dissolves much more moisture, and is twice as expensive as CFC-12.
Isobutane (R-600a) is a hydrocarbon that is miscible with mineral oils, and the resulting mixture is also compatible with compressor materials. However, its low refrigerating capacity (about 60% of that of CFC-12) means that it requires new models with different displacement/motor combinations and so cannot be used for the conversion of existing CFC-12 or R-134a systems. Another problem with isobutene is that it is flammable.
A blend of propane (R-290) and isobutene (R-600a), mixed in equal proportions by weight, has a refrigeration capacity similar to CFC-12 and operates at similar pressures. This blend of hydrocarbons, too, is fully miscible with mineral oil and compatible with compressor materials. HC blend is the refrigerant mostly used when retrofitting existing CFC-12.
There are more than one substitute available for the same ODS and for the same application, yet none of them is without problems. Which substitute is best for a particular equipment is largely determined by the condition of that equipment, the amount of money avai lable, and whether the user is wi II i ng to replace entire components or just the ODS.