FIGURE 1. Ozone depletion potentials (ODPs) of common CFC, HCFC, and HFC refrigerants based on WMO, "Scientific Assessment of Ozone Depletion: 2002," March 2003. (copyright 2003 James M. Calm)

The "alternatives" have become the norm for new equipment in many applications and in conversions for some old equipment. The deceptive ease of the transition masks the enormous investments made by chemical and equipment manufacturers to identify substitutes, develop safety and application data for them, redesign products and service practices, develop and qualify new lubricants and other fabrication material, and test and rate new equipment.

FIGURE 2. Global warming potentials (GWPs) of common HCFC and HFC refrigerants based on IPCC, "Climate Change 2001," "The Scientific Basis, 2001," and WMO, "Scientific Assessment of Ozone Depletion: 2002,\" March 2003. (copyright 2003 James M. Calm)

Progress Being Made

Although stockpiled and recovered chlorofluorocarbon (CFC) refrigerants remain available for service of old systems, the best reasons for replacement of equipment still using CFCs are significant improvements in efficiency with next-generation equipment and resulting cost savings.

Hydrocarbons, primarily isobutane, now dominate in refrigerators in some countries. Likewise, use of ammonia and hydrocarbons (such as propane and propylene) is increasing, most notably in some European countries. While further use of carbon dioxide is exciting, for example in the low stage of cascaded refrigeration systems, its benefits often are overstated for broad application.

Although still underway, the transition has gone so smoothly that most refrigerant users are unaware of the regulatory and political challenges facing many of the replacements. The mantra of ozone protection was to switch to use of hydrochlorofluorocarbon (HCFC) or hydrofluorocarbon (HFC) options, the former on an interim basis. Several key applications still rely on HCFCs, notably R-22 for more than 90% of unitary air conditioners and heat pumps and R-123 for more than two-thirds of new centrifugal chillers. HCFCs are scheduled for phaseout in new equipment in the USA by 2010 and 2020, respectively, with further production allowances to support service needs. For R-123, production for service is allowed until 2030 in developed countries and until 2040 in developing countries. Neither the Montreal Protocol nor regulations in the USA and most other countries restrict further use of existing installed, stockpiled, or reclaimed HCFCs for future service, so there should be more than needed for anticipated service needs.

Some countries and environmentalists now are clamoring for phaseout of HFCs to mitigate global warming. The more extreme of them champion bans of all fluorochemicals well beyond refrigerants, blowing agents, solvents, propellants, and fire suppressants to also eliminate use in such products as synthetic fabrics (such as Gore-Tex) and coatings for cookware (such as Teflon).

FIGURE 3: Progress in reducing refrigerant emissions from leakage, purge venting, and other operating and service losses. (copyright 1999 James M. Calm)

Under Pressure

The overwhelming majority of refrigerant use, and all fluorochemical refrigerant use, is in closed systems that need not release refrigerants for operation. The refrigerants inside systems do not deplete stratospheric ozone. They also do not act as greenhouse gases, though more significant emissions of carbon dioxide and other greenhouse gases from related energy use do. The costs and service needs are lower and efficiency and capacity higher in systems without leaks. Nevertheless, there is scientific evidence that the atmospheric concentrations of some alternatives are increasing more rapidly than explained by reported and attainable emission rates. That suggests that users can influence the future acceptability and ultimate fate of alternative refrigerants through responsible use by: Selecting refrigerants that have very low ozone depletion and global warming potentials (ODP and GWP): Such refrigerants typically also have short atmospheric lifetimes, thereby reducing accumulation in the atmosphere and affording protection from additional concerns. Figures 1 and 2 depict ODP and GWP values for common refrigerants.

Minimizing emissions in manufacture, packaging and repackaging, transport, storage, installation (charging), service, and equipment retirement (recovery): The dramatic reductions in refrigerant releases from chillers (shown in figure 3) from an annualized rate of up to a third of the charge per year three decades ago to less than 0.5% per year in the best equipment today illustrate the potential. That translates to recovery of approximately 90% of the initial charge at equipment retirement instead of a full new charge every three years. Past uses of refrigerants to blow out condensate lines and clean coils are not only unacceptable, but also illegal in the USA and some other countries. Further reductions are possible with future improvements, greater care in handling and service, and immediate response to known leaks. Additional reductions are possible with strategic changes in service frequency for internal and withdrawal procedures. For example, scheduling oil changes based on periodic laboratory analyses of samples avoids excessive changes, each of which releases some refrigerant.

FIGURE 4: Refrigerant generations and their defining characteristics. (copyright 1997 James M. Calm)

Support Needed

The last point warrants explanation. The air-conditioning and refrigeration industry generally espouses use of analyses that include the global warming impacts of both refrigerant releases (sometimes referred to as direct effect) and other greenhouse gas emissions from associated energy use (sometimes referred to as indirect effect, though that term has other meanings in atmospheric science). Such analyses include Total Equivalent Warming Impact (TEWI), Life-Cycle Warming Impact (LCWI), Life-Cycle Climate Performance (LCCP), Net Warming Impact (NWI), and a number of variants. These analyses are useful tools, but also prone to misuse by deliberate or inadvertent distortion of underlying operating assumptions, system boundaries, and data. HFC emissions are small today, 1-2% of controlled greenhouse gas releases measured as carbon-dioxide equivalent, but this fraction is mounting and there is concern that future levels will increase several fold.

Two of the four centrifugal chiller manufacturers in the USA employ R-123. As such, there is a commercial advantage for some to support and some to oppose reconsideration of its currently planned phaseout. Yet this refrigerant offers an opportunity to base regulatory policies on scientific evidence, since a reprieve from phaseout for chiller use would have imperceptible impact on the ozone layer and would avoid an increase of 9-20% in energy-related greenhouse-gas emissions.

R-123 is one of the few controlled substances for which there is a clear environmental rationale for retention as a chiller refrigerant, but that distinction is being distorted in negative marketing and lobbying. A successful campaign to preserve this unique HCFC would set a key precedent for future decisions on HFCs, namely to consider them scientifically on compound-by-compound and application-by-application bases. Alternative restriction of the entire chemical class risks removal of sensible choices along with offensive substances.

TABLE 1: Older and "Alternative" Refrigerants

A Documented Case

The Joint Intergovernmental Panel on Climate Change Technical and Economic Assessment Panel (IPCC-TEAP) Expert Meeting on Options for the Limitation of Emissions of HFCs and PFCs in 1999 noted that phaseout of HCFC-123 will increase ... global warming by 14-20% as contrasted to less than a 0.001% increase in peak bromine-chlorine loading. Although controversial, the working group agreed that HCFC-123 use warrants examination for chillers based on its negligible impact on ozone depletion and strong benefit in reducing global warming.

The 2002 assessment Report of the Refrigeration, Air-Conditioning, and Heat Pumps Technical Options Committee (RTOC), prepared under the auspices of the United Nations Environment Program (UNEP), stated that HCFC-123 has a favorable overall impact on the environment that is attributable to five factors: (1) a low ODP, (2) a very low GWP, (3) a very short atmospheric lifetime, (4) the extremely low emissions of current designs for HCFC-123 chillers, and (5) the highest efficiency of all current options. This international assessment cites studies showing that continued use of HCFC-123 in chillers would have imperceptible impact on stratospheric ozone while offering significant advantages in efficiency, thereby lowering greenhouse gas emissions from associated energy use.

The transition to and outcome for third generation refrigerants as depicted in figure 4 is underway. Upcoming decisions will determine the long-term viability of the current options. Manufacturers and users of refrigerant and equipment can influence their future by selecting refrigerants with low ODP and low GWP, minimizing emissions, increasing system efficiency, and supporting scientific determination of control measures. That future depends on responsible stewardship of remaining options, both in use and advocacy.ES

This article was translated from J. M. Calm, "Responsible Responses to Refrigerant Regulation." Engineered Systems, 20(10):66-80, October 2003, and is republished with permission of the author. 2003 James M. Calm all rights reserved.