\NEWS FOCVS\
Looming Ban on Production ofCFCs, Hâtons Spurs Switch to Substitutes Even while the transition takes place, work is under way on a second generation of alternative compounds and technologies Pamela S. Zurer, C&EN Washington lake a second and pat yourself on the back," Paul Norris, president of AlliedSignal Chemicals & Catalysts (Morristown, N.J.) told an international conference on chlorofluorocarbon (CFC) and halon alternatives last month in Washington, D.C. He had just complimented the audience of engineers, scientists, and businesspeople from the indus tries that produce and use ozone-depleting chemicals on the rapid progress they've made toward phasing them out. "But then quickly come back to reality," Norris contin ued. '"We've got lots to do over the next two to three years." The tight time frame Norris cited is set by the international treaty called the Montreal Protocol on Substances That De plete the Ozone Layer. The latest revisions to the treaty dictate an end to industrialized countries' production of CFCs, carbon tetrachloride, and methyl chloroform by Jan. 1,1996. Halons—brominated fluorocarbons used for fighting firesface a production ban Jan. 1,1994, just seven weeks from now. The countries that are party to the treaty agreed to those accelerated deadlines last November because of a steady flow of bad news about the damaged strato spheric ozone layer. The sit uation has only worsened since then. The most recent Antarctic ozone hole was the deepest ever recorded (C&EN, Oct. 25, page 24). And unprecedented low levels of ozone have been observed over the North ern Hemisphere through out much of 1993 (C&EN, Oct. 4, page 5). So far, the 10-year grace period for developing coun tries built into the original Montreal protocol has been allowed to stand. But these countries, too, may face an accelerated phaseout when the grace period is reevaluat ed in 1995. The continuing deterio
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NOVEMBER 15,1993 C&EN
ration of the ozone layer may also prompt tighter controls on hydrochlorofluorocarbons (HCFCs), which are scheduled to be phased out by 2030. Those CFC substitutes, although not nearly so damaging as the fully halogenated compounds they are replacing, do carry some ozone-depleting chlorine into the stratosphere. Worldwide, CFC output has already decreased to half of its 1986 level of 1.13 million metric tons and is 15% lower than just a year ago, according to Norris. He pointed out, however, that the Montreal protocol allows production in 1994 and 1995 at only 25% of 1986 levels. "The users must now accelerate their efforts if we are to meet our 1996 goals without disruption to the public," he said. How hard it will be to give up the remaining uses of banned ozone-depleting chemicals varies widely among in dustry sectors. The U.S. electronics industry, which six years ago relied heavily on CFC solvents for precision cleaning, is already virtually CFC-free. Major electronics companies are now working to help their counterparts in developing nations make the transition. The U.S. appliance indus try, which a year and a half ago feared it would be in deep trouble without an ex emption from the CFC ban (C&EN, June 22,1992, page 7), believes it has solved some thorny conversion problems. It has chosen hydrofluorocarbon-134a (HFC-134a, C B J O y to replace CFC-12 (CC12F2) in the compressors of home refrigerators, and the polyurethane foam insu lation in refrigerator walls will soon be blown with HCFC-141b (CH3CC12F) in stead of CFC-11 (CC13F). Almost all new cars and trucks sold in the U.S. are now equipped with airconditioning systems that use HFC-134a, the result of "unprecedented parallel de velopment efforts," accord ing to Norris. "Even as the chemical industry waited for
final results of toxicological studies on new refrigerant HFC134a, the automobile industry began using the compound in new air-conditioning systems for cars and trucks. As a result, the CFC-free systems were developed in only three years." The next hurdle will be servicing older cars once the supply of CFC-12 used in their systems runs out. Auto repair shops will be where most consumers first face the hassle and expense of the CFC phaseout. Alternative compounds for commercial refrigeration and building air-conditioning are now available in good supply. But building owners have been dragging their feet, unwilling to invest in new equipment or to pay to retrofit their old stock to use the new chemicals. The Building Owners & Managers Association International petitioned EPA last summer for an exemption from the CFC ban (C&EN, Aug. 16, page 15), but was turned down. Halon users are coping with the precipitous 1994 production cutoff by carefully husbanding the existing supply. The nonprofit Halon Recycling Corp., based in Washington, D.C., is helping to match companies that have excess halons with those that need them for critical uses such as aircraft fire protection. The Defense Logistics Agency has set up a similar halon bank for the military. Although a true drop-in replacement for halons has yet to be developed, a new candidate, trifluoromethyl iodide (CF3I), is raising hopes. The increasing urgency of moving out of CFCs has been reflected in the growth in attendance at the International CFC & Halon Alternatives Conference. The annual conference is sponsored by the Alliance for Responsible CFC Policy (a coalition of businesses that produce and use CFCs), the Environmental Protection Agency (EPA), Environment Canada, and the United Nations Environment Program (UNEP). When the first such meeting was held in early 1988, about 500 people attended, most of them highly technically oriented. Such technical folk still made up the majority of the approximately 2000 people who attended the October 1993 conference. But in addition, a significant number of purchasing agents, property managers, and the like showed up this year, observed Stephen O. Andersen, acting deputy director of EPA's stratospheric protection division. They are the people who must decide how and when to replace or retrofit equipment that now depends on CFCs. "It's been fun to watch the representatives from [grocery stores] wandering around the exhibit area," Andersen told C&EN. "You can see them in front of the National Refrigerants' booth, which has freezers running on the alternatives on display. They seem amazed the freezers really work." At the conference's opening plenary session, Andersen praised the electronics and aerospace industries for the work they have done in eliminating the use of CFC-113 (CC12FCC1F2) and methyl chloroform solvents. Through the Industry Cooperative for Ozone Layer Protection (ICOLP), major firms have been sharing technology for ozone-safe metal cleaning and now are reaching out to developing countries. For example, in 1987 IBM's San Jose, Calif., manufacturing facility was the largest industrial emitter of CFCs (1.5 million lb) in the U.S. The company has switched completely to water-based cleaning and drying technologies for circuit boards and disk components. With the cost of CFCs rising, the firm estimates it is saving millions of dollars annually. Through ICOLP, IBM is taking part in a World Bank-funded project to help companies in countries such as
Levels of chlorine in stratosphere will decrease slowly under Montreal protocol Cumulative stratospheric chlorine equivalent, ppb
4
Total \ chlorine
/ Methyl bromide Halons
3
HCFCs Carbon tetrachloride
2 Methyl chloroform
1
Chlorine level at which Antarctic ozone hole appeared
CFCs
"Natural"methyl bromide "Natural1methvl chloride
0
1979 84 89 94 99 2004 09 14 19 24 29 34 39 44 49 54
Note: Ozone-depleting effects of bromine atoms in halons and methyl bromide have been converted to their chlorine equivalents. Source: DuPont
Brazil, China, India, Malaysia, Mexico, Thailand, and Turkey phase out the use of ozone-depleting solvents. In contrast to those high-tech firms, U.S. building owners seem almost paralyzed. "One of the challenges of 1994 is to persuade building owners to act now," EPA's Andersen said. 'If they wait too long to convert, there will be shortages of engineering personnel, equipment, and the chemicals themselves." Building owners have been hesitant to switch out of CFCs both because of the expense—an estimated $1.6 billion to replace or retrofit the nation's thousands of existing
EPA plans to phase\ out HCFCs in stages Date3
Compounds affected
1994
All HCFCs
2003
HCFC-141b (CH3CCI2F, ODPb = 0.12) HCFC-22 (CHCIF2) ODP = 0.05) HCFC-142b (CH3CCIF2, ODP = 0.06)
2010
2015
All other HCFCs
2020
HCFC-22, HCFC-142b All other HCFCs
2030
Restriction
Ban on use in aerosols (except medical devices) and plastic foams (except foam insulation) Ban on production and imports
Production and imports frozen at 1989 baseline levels. Ban on use of virgin chemical, unless used as feedstock or for servicing refrigeration or air-conditioning equipment manufactured before Jan. 1, 2010 Production and imports frozen at 1989 baseline levels. Ban on use of virgin chemical, unless used as feedstock or for servicing refrigeration or air-conditioning equipment manufactured before Jan. 1, 2020 Ban on production and imports Ban on production and imports
Note: HCFCs = Hydrochlorofluorocarbons. a Effective date is Jan. 1 of the given year, b ODP = Estimated ozone depletion potential, which depends on chlorine content and atmospheric lifetime. Potentials are relative to CFC-11, which is assigned a value of 1.0. Source: Federal Register. March 18. 1993. page 15,014, and Sept. 27, 1993. page 50.464
NOVEMBER 15,1993 C&EN
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Greenfreeze: Greenpeace's chilly message to chemical companies Just down the street from where the International CFC and Halon Alternatives Conference was held last month, Greenpeace hosted its own countersymposium two days earlier. The international environmental group's Ozone-Safe Cooling Conference showcased innovative technologies that do not rely on hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (HFCs), the two major classes of chlorofluorocarbon (CFC) alternatives. Greenpeace believes production of HCFCs and HFCs should cease immediately: HCFCs because they have some potential to deplete the ozone layer, and HFCs because they are greenhouse gases. The group rejects the position of the United Nations Environment Program and the Environmental Protection Agency (EPA) that the compounds are important interim substitutes, speeding the transition away from CFCs. "It is possible for entire industries to leapfrog from CFCs to ozone-safe compounds, completely avoiding HCFCs and HFCs," said Melanie Duchin of Greenpeace's ozone campaign as she opened the meeting. Such technological alternatives are commercially available but have been virtually ignored by EPA and large companies, Greenpeace asserts. Despite Greenpeace's reputation as an extremist organization, the 200 or so people who attended its conference were sur-
prisingly mainstream. Large heating, ventilation, and air-conditioning firms came to hear new ideas, as did major chemical companies. Aside from one strident talk by a Greenpeace staff member, most of the presentations would not have been out of place at the CFC alternatives conference later in the week Several of the invited speakers presented new technologies they are eager to see commercialized, such as cooling with sound waves, known as thermoacoustic refrigeration. Others presented the latest twists on once-popular systems that were supplanted years ago by CFCs, including "natural" refrigerants like hydrocarbons, ammonia, and water. "I'm fascinated by the contrast between the new cutting-edge technologies and the old, almost forgotten technologies being presented here" at this meeting, said speaker John J. Kinney of Norsaire Systems, Denver. Center stage for one morning session was the Greenfreeze, a small domestic refrigerator developed in Germany. The refrigerator uses a propanebutane mixture as the refrigerant instead of HFC-134a, which U.S. appliance manufacturers are using to replace CFC-12. The polyurethane foam insulation in the walls of the Greenfreeze is blown with cyclopentane, avoiding HCFC-141b, the current replacement of choice for CFC-11. In early 1992, Greenpeace commis-
centrifugal chillers—and the uncertainty over the long-term fate of the substitutes. The majority of such chillers run on CFC-11 and could be converted to HCFC-123 (CHC12CF3). The Montreal protocol classifies HCFCs like HCFC-123 as "transitional" substances, capping their production in 1996 and then gradually phasing them out over the following 35 years. The hydrogen atoms on HCFCs make them susceptible to oxidation in the troposphere (the lower atmosphere), but a fraction of molecules emitted at the surface survive to carry ozone-destroying chlorine into the stratosphere. Both UNEP and EPA maintain that the accelerated phaseout of CFCs can be managed only if HCFCs and hydrofluorocarbons (HFCs) are used instead. In the U.S., EPA has proposed phasing out those HCFCs with the largest ozonedepletion potential first, while allowing other HCFCs to remain on the market longer. Under the regulation EPA proposed last March, HCFC123—with a relatively low ozone-depletion potential— could be produced for use in existing equipment through 2030, certainly a long enough lead time to justify investment in the mid-1990s. But potential users are anxious about the pressure from environmental groups to ban HCFCs sooner. For example, Greenpeace advocates an immediate end to all 14
NOVEMBER 15,1993 C&EN
Millais: Greenfreeze (right) is one nail in chemical companies' coffin sioned DKK Scharfenstein, which had been a leading appliance manufacturer in the former East Germany, to build 10 prototypes of the Greenfreeze. Orders flooded in after Greenpeace launched an advertising campaign, said Corin Millais of Greenpeace's London office. Now several German firms are manufacturing hydrocarbonbased refrigerators and freezers. "We focused on the domestic fridge in order to disprove and overturn the conventional wisdom of chemical companies that no substitutes were
HCFC production. "HCFCs add chlorine to the atmosphere at the crucial time when it is most vulnerable," William Hare of Greenpeace's climate division said at a conference in October. The meeting was organized by Greenpeace to promote cooling technologies that avoid HCFCs and HDFCs as well as CFCs. In addition, Congress, always eager to enhance revenues, is contemplating a tax on HCFCs. Perry Plumart, press secretary to Rep. Pete Stark (D.-Calif.), a member of the taxwriting House Ways & Means Committee, said at the CFC alternatives conference that "HCFC taxes are inevitable/' U.K.-based ICI, a former CFC producer, is not even bothering to manufacture the new HCFCs, focusing instead on developing HFC-134a and other HFCs. "In the mid-1980s we chose to stay away from transitional solutions and look for long-term answers," ICI applications product leader Janet Schukraft told C&EN. "Our customers indicated they wanted to change once and get it over with." But other major chemicalfirms,like DuPont and AlliedSignal, have invested heavily in HCFCs. "We've developed HCFCs to support our customers," said Mark J. Byrne, vice president of AlliedSignal Huorocarbons. "There were no HFC substitutes for insulation foam, for example. If it were an easy transition straight to HFCs from CFCs, we would have done it."
available that would work except HCFCs and HFCs," Millais said. "The chemical companies have put billions of dollars into HCFCs and HFCs. They want their money back, even if [their products] are bad for the environment." Hydrocarbon refrigerants can be as energy efficient as fluorocarbons if the whole cooling system is optimized, Manfred Doehlinger told the conference. Doehlinger, a refrigeration engineer with Energitechnik Institute in Northeim, Germany, said the major drawback to the use of hydrocarbons is their flammability. "But flammability is a limited, local problem that can be managed by engineering," he said. "Everybody drives a
car filled with flammable stuff eveiy day and nobody thinks a thing about it" The Greenfreeze incorporates hermetically sealed lighting to prevent an explosion if the hydrocarbon refrigerant should leak into the interior of the refrigerator, said Albrecht Meyer of Scharfenstein. The charge is so small— only about 20 g—that there is no danger of explosion if it leaks outside the refrigerator, he said. Nevertheless, U.S. refrigerator producers are planning to steer clear of hydrocarbon refrigerants. U.S. society is so litigious that the added risk— both in the home and at the manufacturing plant—does not seem worth the supposed benefits, Brooke Stauffer of the Association of Home Appliance Manufacturers tells C&EN. Similarly, U.S. manufacturers are shying away from polyurethane foam insulation blown with cyclopentane. The foam itself performs well, although it is not quite as good an insulator as polyurethane blown with HCFC-141b, according to Michael J. Cartmell, technical service manager of ICI Polyurethanes Group in West Deptford, N.J. But foam factories would need scrubbers to control emissions of cyclopropane, which as a volatile organic compound is regulated as a smog precursor under the Clean Air Act, Cartmell says. The long-term solution for
Even HFCs, which present zero risk to the ozone layer because they bear no chlorine atoms, are under attack from certain quarters because they are greenhouse gases that contribute to global warming. "I believe promoters of HFCs . . . are advocating jumping out of the ozone frying pan and into the climate fire," Greenpeace's Hare said. The first concrete signal that HFCs will be regulated in the future arrived Oct. 19 in President Clinton's Climate Change Action Plan, designed to reduce greenhouse gas emissions through voluntary measures (C&EN, Oct. 25, page 4). Among the 50 programs described in the plan is a voluntary commitment by six U.S. chemical producers to cut emissions of HFC-23 (CHF3), a by-product of the manufacture of HCFC-22 (CHC1F?). The plan also directs EPA to restrict uses of HFCs with high global-warming potential in cases where better alternatives exist. Anxiety over the fate of HCFCs and HFCs has led the Alliance for Responsible CFC Policy to change its name to the Alliance for Responsible Atmospheric Policy. Now that CFCs are on the way out and global warming is garnering increasing attention, the organization wants its name and focus to better address its members' concerns, says executive director Kevin Fay. Even chemical companies that produce HCFCs are devel-
appliance insulation will be vacuum insulation panels, he predicts. EPA representatives deny that the agency has given short shrift to alternative technologies such as those promoted by Greenpeace. In the case of hydrocarbon refrigerants, for example, no manufacturer or environmental group has yet applied to have the chemicals' risk to health and human safety evaluated under EPA's Significant New Alternatives Program (SNAP), says Jeffrey Levy, EPA's refrigerant specialist. Once the agency's proposed SNAP rule becomesfinalin February, it will be illegal to market alternatives for CFCs and halons that are not on its list of acceptable substitutes. "We haven't even gotten a submission for hydrocarbon refrigerants," Levy says. "We told [Greenpeace that the producers have] got to get on our list" Nevertheless, Greenpeace's Millais insisted it is the chemical industry that is holding back ozone-safe technologies like the Greenfreeze. "We used the fridge to prove the chemical industry is wrong" when it said it would take 10 years to develop a propane refrigerator, Millais said. "The Greenfreeze is one nail in the coffin of the chemical companies. We need more nails to bang the lid down for good. That's the only way we will really save the ozone layer."
oping replacements for them. DuPont, for example, is testing a blend of three HFCs as a replacement for HCFC-22 in residential heat pumps and air conditioners. AUiedSignal has identified four HFCs as candidates to replace HCFC141b for blowing polyurethane foams. HCFC-141b had become the substitute of choice for blowing foam insulation, because trapped within the foam it is almost as good an insulator as the CFC-11 it is replacing. But HCFC-141b can only be used for the next decade. Because of the relatively high ozone-depletion potential of HCFC-141b, EPA has proposed banning its production and consumption by 2003. Appliance manufacturers have relied heavily on CFC-11 foams in the walls of refrigerators and are switching to HCFC-141b as an interim solution. But they are also looking at vacuum panel insulation, a totally different concept. Vacuum panels incorporate a solid filler material that is sealed under vacuum in a gas-tight envelope. At the CFC alternatives conference, representatives from BASF in Ludwigshafen, Germany, described vacuum panels filled with an amorphous silica aerogel. Researchers from ICI Polyurethanes in Belgium presented an open-celled rigid polyurethane, blown with carbon dioxide, that they have incorporated into vacuum panels. NOVEMBER 15,1993 C&EN 15
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FOCUS
Desiccant air-conditioning system uses no refrigerants or compressors By combining two technologies that have been around for years—evaporative cooling and desiccant drying—a number of companies are hoping to market air-conditioning systems that use no refrigerants or compressors. The new systems successfully address three major concerns about conventional airconditioning—energy efficiency, environmental safety, and indoor air quality—according to P. Richard Heimann, director of energy services at ICC Technologies, Philadelphia. Heimann described his company's evaporative-solid desiccant air-conditioning system last month at Greenpeace's Ozone-Safe Cooling Conference. A nearly identical system was presented by representatives of LaRoche Chemicals, Baton Rouge, La. And a variation using a liquid desiccant was reported by Albers Corp., Tempe, Ariz. Interestingly, LaRoche currently manufactures both chlorofluorocarbons (CFCs) and the fluorocarbon alternatives—the very chemicals that the new desiccant systems could displace. "We've been looking into desiccant
systems for seven years," says William G. Osborne, the company's vice presl* dent and general manager of corporate operations. "We make refrigerants, but we see which way the world is heading." At the core of the new systems is an old technology known as evaporative cooling—the natural evaporation of water, the same process that cools a sweating human body. In evaporative air-conditioning's simplest form, hot air is drawn through a water spray or through wet porous pads. The air becomes cooler and more humid as it takes up water. The only moving parts requiring electrical power are a fan and a small water pump. Such systems are known generically as "swamp coolers"—a misnomer, according to John J. Kinney with Norsaire Systems, Denver, in that humid swamps are one area where they do not work. The name probably arose from the unfortunate odors that can emanate from a poorly maintained system. Currently, only about 5% of the U.S.'s 86 million households use evap-
orative coolers, Kinney says. Those residences are mainly in the Southwest. (For comparison, the Department of Energy estimates about two thirds of U.S. households rely on vapor-compression air-conditioning systems that contain fluorocarbon refrigerants.) "Evaporative cooling is an excellent technology for low-cost cooling that works best in desert areas," says William A. Belding, a consultant to LaRoche who is president of Innovative Research Enterprises, Danville, Calif. "By adding a desiccant we can bring a desert climate to all areas of the country." Both LaRoche's and ICC Technologies' systems incorporate a rotating wheel containing a solid desiccant. The air passing through is dried and heated by the heat of absorption associated with the desiccant. The resulting warm dry air—now desertlike—is then cooled by passing through a heat exchanger and finally an evaporative cooling unit. The desiccant is reactivated by outside air that is heated with a gas burner. "We see our role as a manufacturer
mobiles on the road that have systems that use CFC-12," AlliedSignal's Norris said. "They'll pay high prices for banked CFC-12—if if s available—or face the cost of converting to systems that can use HFC-134a. Even the lowest cost retrofits are still relatively expensive." About 140 million cars with CFC-12 systems are on the road in the U.S. today. In 1991, the auto industry estimated retrofitting costs would range from $200 to $1200 per car, depending on the make, model, and year. Besides removing the CFC-12, which is incompatible with HFC-134a, it was thought that hoses, O-rings, the lubricant, and, in some cases, even the compressors would have to be replaced. But after a few years of experience with retrofitted vehicles, it appears the high end of the cost range may have been overestimated. In many cases, fewer modifications to the original air-conditioning systems will have to be made than were feared. Although the original mineral oil lubricant—which is immiscible with HFC-134a—must be replaced with either a polyol ester or polyalkylene glycol oil, other system components designed for CFC-12 appear to be working well with HFC-134a. For example, in laboratory tests HFC-134a leaks much faster through rubber hoses than CFC-12 because it operates at higher pressure. That suggests the original hoses on many cars Nimitz prepares to extinguish candle flame with CF*om should be replaced with less permeable ones. 3I fn balloon.
Most consumers likely will never know whether their refrigerators are insulated by foam blown with CFC-11 or HCFC-141b or by vacuum panels. But they surely will know something has changed the next time they want to get their cars' air conditioners serviced. "The biggest direct consumer impact will come from auto-
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NOVEMBER 15,1993 C&EN
of desiccant wheels/' says Osborne. "When we began, our objective was to develop a desiccant that could be used in a cooling system that would be costcompetitive with a vapor-compression unit. We hope to team up with existing
HVAC [heating, ventilating, and airconditioning] companies." Osborne declines to describe the desiccant LaRoche has developed, except to say that its properties lie between those of silica gel and molecular
Innovative system cools and dries indoor air Warm humid outside air
Cooler I wet air
Hot humid air
Very hot dry air Hot humid air discharged to outside
Gas burner
Cool / comfortable air
Hot dry air Cooler Evaporative dry airr Heat coolers exchanger wheel
Desiccant wheel
Recirculated warm humid air
In practice, the old rubber hoses aren't nearly so leaky, according to Thomas W. Dekleva, ICI's North American technical service manager. Dekleva described the results of two years and 1 million test miles on a wide spectrum of cars retrofitted with HFC-134a and ICFs ester lubricant. "We've found in most cases the original hoses worked fine/' he said. "In some cases, 134a leaked less. The lubricant has a big effect on reducing leakage. It appears original hoses shouldn't be a big problem and we're recommending leaving them in place." Overall, Dekleva said, most of the air conditioners on ICI's test cars performed just about as well with HFC-134a as with CFC-12. He found it especially telling that none of the vehicles' owners took ICI up on its offer to convert their cars back to CFC-12 at the end of the trial. Volvo has already started supplying its dealers with retrofitting kits. "We are pricing the kits low to encourage customers to take the environmentally beneficial option" of retrofitting, said Richard Reina of Volvo Cars of North America's regulation and compliance office. Volvo set the suggested retail price of the required parts at $45. Adding the approximately $21 charge for 2 lb of HFC-134a and another estimated $200 for labor, the total charge comes to less than $300. That price is within the range U.S. customers would be willing to pay for a retrofit, according to a new survey by the Mobile Air Conditioning Society (MACS). But MACS, which represents auto air-conditioning servicers, is afraid that retrofitting will be driven by "low down and dirty" pricing, said Ward Atkinson of Sun Test Engineering in Scottsdale, Ariz.
sieves. The company expects to fieldtest 10 desiccant-assisted cooling units this summer, financed in part by the Gas Research Institute of Chicago. ICC Technologies' system employs a patented titanium silicate molecular sieve developed by Engelhard Corp. of Iselin, N.J. That firm will have 25 to 50 units in field demonstrations next year, also with funding from the gas industry. A major advantage of the desiccantassisted cooling systems is that they allow independent control of temperature and humidity. "There are many months in Atlanta, for example, when you need humidity control but not cooling," notes Heimann. And there are many nighttime hours in the summer in, say, Washington, D.C., when only dehumidification is needed for comfort. Drier air can also improve indoor air quality by discouraging the growth of molds in air ducts. Desiccant wheels are expensive right now, even though the materials themselves are cheap, Heimann says. But both firms believe the cost will fall dramatically when they begin large-scale production.
MACS is particularly concerned about certain blends of chemicals that are currently being marketed as CFC-12 replacements. None of these flammable or potentially flammable blends are on EPA's list of proposed acceptable alternatives for auto air-conditioning under its Significant New Alternatives Program (SNAP). Until the agency finalizes its SNAP regulations—which under court order it must do by Feb. 14, 1994—the problematic alternatives can be sold legally. Of greatest concern to MACS is a product called OZ-12, marketed by OZ Technology, Post Falls, Idaho. It consists of a blend of cheap propane and butane. "The use of flammable ... refrigerants poses safety concerns to the technicians servicing mobile air-conditioning systems," states an October bulletin from MACS. Toyota, too, is anxious about the proliferation of CFC-12 replacement blends. "If we add just one refrigerant in addition to CFC-12 and HFC-134a, the problem of cross-contamination will increase by an order of magnitude," said Toyota's Gary Smith. "Throw in blend gases and chaos is inevitable." While the auto industry worries about the confusion that may result from too many substitutes on the market, halon users face a very different problem. The abrupt cessation of halon production will not result in an immediate shortage of these chemicals. UNEP estimates the current supply is large enough to last until the middle of the next century, now that the practice of discharge testing has been halted and other unnecessary emissions curtailed. Time will soon tell if the halon banking systems that have been set up will really work NOVEMBER 15,1993 C&EN
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in recycling the existing supply from nonessential to essential uses. So far no definitive alternatives have been found that come close to matching the halons' effective ness at extinguishing fires, lack of toxicity, and vol atility while avoiding their global environmental liabilities of high ozone-depletion and globalwarming potentials. But two research groups are pushing CF3I as a near-perfect replacement for halon-1301 (CF3Br), the "magic gas" used to totally flood enclosed spaces such as offices, airplanes, and military tanks in case of a fire. "CF3I seems to be the only one of hundreds of chemicals we've looked at that appears to be a true drop-in replacement for 1301," said Stephanie R. Skaggs, deputy director of the Center for Global Environ mental Technologies at the New Mexico Engineering Research Institute (NMERI). Skaggs reported at the alternatives conference that the fluoroiodocarbon (FIC) is essentially identical to halon-1301 in tests of its effectiveness at extinguishing fires. Chemist Jon Nimitz, president of the Environmental Tech nology & Education Center, Albuquerque, N.M., and his part ner are investigating a variety of FICs as substitutes for halons and CFCs. Both NMERI and Nimitz's consulting firm have filed for patents on various uses and compositions of FICs. Nimitz noted that carbon-iodine bonds are easily photolyzed by sunlight at Earth's surface. The resulting short at mospheric lifetime means the compounds are unlikely to contribute to ozone depletion or global warming. Unpublished calculations on CF3I performed at the National Oceanic & Atmospheric Administration's (NOAA) aeronomy lab in Boulder, Colo., back that conclusion. "Preliminary data certainly support the view that the lifetime of CF3I is very short in the atmosphere, on the order of a few days," NOAA research chemist Susan Solomon tells C&EN. ^ s e d on that, if s highly likely that the stratospheric ozone-depletion effect of a molecule released at the ground is very small." But an FIC molecule emit ted at high altitude could be another story. It is not yet clear whether releases in the upper troposphere or stratosphere could trigger ozone depletion. That concern is not trivial, because the military has chosen CF3I as one of three finalists it is considering for fire protection in aircraft engine enclosures. "Our conditions are unique," says Michael Bennett, tech nical director of the halon replacement program at WrightPatterson Air Force Base, near Dayton, Ohio. "Winds are streaming through the fire area at hundreds of miles per hour. We have to put the fire out within milliseconds. "So far, CF3I appears to work extremely well," he tells C&EN. "However, there are still questions about corrosion, toxicity, and ozone-depletion potential." Toxicity and corrosivity data on FICs are scarce, but so far no "show-stopping" negative results have turned up, according to Skaggs. A key toxicity test of cardiac sensitivi ty is needed, she said, but has not yet been funded. To show his confidence in the safety of CF3I—which he suggested should be labeled as "providing iodide, a neces sary nutrient"—Nimitz re-created the famous demonstra tion performed by CFC inventor Thomas Midgley at the 1941 American Chemical Society meeting in Atlantic City, N.J. Nimitz extinguished a candle with a lungful of CF3I, just as Midgely did with CFCs. 18
NOVEMBER 15,1993 C&EN
Retrofitting automotive air-conditioning units will be an aggravation and expense to consumers; Volvo is already supplying dealers with reasonably priced kits. EPA representatives are somewhat uneasy about the hype currently surrounding CF3I. The agency has not yet received an application to place the compound on its SNAP list of approved halon substitutes. 'The material is in its in fancy in terms of research," says EPA halon specialist Karen Metchis. 'There's a lot of toxicological data yet to be devel oped. We'll be thrilled if it turns out to be a drop-in replace ment, but it's too early to tell." The price of the currently obscure and expensive FICs may prove another stumbling block. Both Skaggs and Nimitz pre dict prices will fall when production is scaled up. Skaggs projected the price of CF3I, which she said has already dropped from $300 per lb in May to $150 per lb now, will decline to between $20 and $30 per lb if purchased in mil lion-pound lots. Whether replacing halons or CFCs, with substitute chem icals or entirely new technologies, the transition from the once ubiquitous chemicals will be felt in all sectors of U.S. business and industry in the next few years. "The mantle of responsibility is starting to come off the chemical industry's shoulders and on to the users'," ICI Klea's commercial director Anthony G. Mash says. "It's time for bold strategies. We are coming up against some very severe deadlines." Π
