Ozone-Depleting Substances Alternatives by RodneySooialo

VIEWS: 129 PAGES: 8

									                                                                         Pollution Prevention and Abatement Handbook
                                                                                                WORLD BANK GROUP
                                                                                                     Effective July 1998




Ozone-Depleting Substances: Alternatives


Surrounding the earth at a height of about 25              international environmental agreement, and its
kilometers is the stratosphere, rich in ozone,             signing by so many nations represented a major
which prevents the sun’s harmful ultraviolet               accomplishment, and a major shift in the ap-
(UV-B) rays from reaching the earth. UV-B rays             proach to handling global environmental prob-
have an adverse effect on all living organisms,            lems. The Protocol called for a freeze on the
including marine life, crops, animals and birds,           production of halons and a requirement to reduce
and humans. In humans, UV-B is known to af-                the production of CFCs by 50% by 1999. How-
fect the immune system; to cause skin cancer, eye          ever, new scientific evidence surfaced after the
damage, and cataracts; and to increase suscepti-           entry into force of the Protocol, indicating that
bility to infectious diseases such as malaria.             ozone depletion was more serious than originally
   In 1974, it was hypothesized that chlorinated           thought. Accordingly, in 1990 (London), 1992
compounds were able to persist in the atmo-                (Copenhagen), and 1995 (Vienna), amendments
sphere long enough to reach the stratosphere,              were made to the Protocol to regulate the phase-
where solar radiation would break up the mol-              out of the original chemicals and the control and
ecules and release chlorine atoms that would               phase-out of additional chemicals.
destroy the ozone. Mounting evidence and the
discovery of the Antarctic ozone hole in 1985 led
to the global program to control chlorofluorocar-          Table 1. Ozone Depletion Potential (ODP) of the
bons (CFCs) and other ozone-destroying chemi-              Principal Ozone-Depleting Substances (ODSs)
cals. In addition to Antarctica, ozone loss is now              ODS                               ODP
present over New Zealand, Australia, southern
Argentina and Chile, North America, Europe,                     CFC-11                             1.0
and Russia.                                                     CFC-12                             1.0
   The ozone-depleting chemicals or substances                  CFC-113                            0.8
                                                                CFC-114                            1.0
(ODSs) of concern are CFCs, halons, methyl chlo-                CFC-115                            0.6
roform (1,1,1,-trichloroethane; MCF), carbon tet-               CFC-111, -112, -13, -211, -212,
rachloride (CTC), hydrochlorofluorocarbons                       -213, -214, -215, -216, -217      1.0
(HCFCs), and methyl bromide. The ozone deple-                   Halon 1211                         3.0
tion potential (ODP) for these chemicals is shown               Halon 1301                        10.0
in Table 1. CFC-11 was assigned an ODP of 1.0;                  Halon 2402                         6.0
                                                                Carbon tetrachloride (CTC)         1.1
all other chemicals have an ODP relative to that
                                                                Methyl chloroform (MCF);
of CFC-11. An ODP higher than 1.0 means that                     1,1,1-trichloroethane             0.1
the chemical has a greater ability than CFC-11 to               HCFC-22                            0.05
destroy the ozone layer; an ODP lower than 1.0                  HCFC-123                           0.02
means that the chemical’s ability to destroy the                HCFC-124                           0.02
ozone layer is less than that of CFC-11.                        HCFC-141b                          0.15
   In September 1987, the Montreal Protocol on                  HCFC-142b                          0.06
                                                                HCFC-225ca                         0.01
Substances That Deplete the Ozone Layer (the
                                                                HCFC-225cb                         0.04
Protocol) was signed by 25 nations and the Eu-                  Methyl bromide                     0.7
ropean Community. The Protocol was the first


                                                     250
                                                              Ozone-Depleting Substances: Alternatives   251


   The principal provisions of the Montreal Pro-        preinvestment studies, training and work-
tocol as it now stands are as follows:                  shops, demonstration projects, investment
                                                        project design, and country programs.
• Production of CFCs, halons, methyl chloro-
                                                      • The United Nations Industrial Development Or-
  form, and CTC ceased at the end of 1995 in
                                                        ganization (UNIDO) implements small and me-
  industrial countries and will cease by 2010 in
                                                        dium-scale projects, feasibility studies at the
  developing countries. Developing countries
                                                        plant level, technical assistance and training,
  are defined in the Protocol as those that use
                                                        and country programs.
  less than 0.3 kilograms (kg) of ODS per capita
  per year. They are often called Article 5 coun-
                                                      Uses of ODSs
  tries in reference to the defining article in the
  Montreal Protocol.
                                                      In general, ODSs are most often used in the fol-
• HCFCs, originally developed as a less harm-
                                                      lowing applications:
  ful class of CFC alternatives, will be phased
  out by 2020 in industrial countries, with some      • As propellants in aerosols (CFCs and HCFCs)
  provisions for servicing equipment to 2030.         • In refrigeration, air conditioning, chillers, and
  Developing countries are to freeze consump-           other cooling equipment (CFCs and HCFCs)
  tion by 2016 (base year 2015) and phase out         • To extinguish fires (halons)
  use by 2040.                                        • In the manufacture of foams (CFCs and
• Consumption and production of methyl bro-             HCFCs)
  mide will end in 2005 in industrial countries       • As solvents for cleaning printed circuit boards
  (subject to phase-out stages and exemptions)          and precision parts and degreasing metal parts
  and in 2015 in developing countries.                  (CFCs, HCFCs, methyl chloroform, and CTC)
                                                      • In a variety of other areas, such as inks and
   It was early recognized that undue hardships
                                                        coatings and medical applications (CFCs,
might be experienced by industry in developing
                                                        HCFCs, methyl chloroform, and CTC)
countries as they implemented replacement tech-
                                                      • As a fumigant (methyl bromide).
nologies. Therefore, a fund was established un-
der the Montreal Protocol to pay for incremental
                                                      Alternative Technologies, Processes,
costs such as technical expertise and new technolo-
                                                      and Chemicals
gies, processes, and equipment associated with the
phase-out. The Multilateral Fund of the Montreal
Protocol is managed by an executive committee         The following discussion provides a brief over-
consisting of delegates from seven developing         view of the alternatives to ODSs that have been
countries and seven industrial countries. The fol-    developed in various sectors. It is not intended
lowing international organizations have been          to be an exhaustive listing of all alternatives, but
made Implementing Agencies of the Multilateral        it does summarize some proven alternatives and
Fund for the purpose of helping governments           give an indication of future development trends.
and industries in developing countries with their     The selection of any alternative should be made
programs to eliminate ODSs. (The roles outlined       with due consideration of other issues that could
here are not intended to be exhaustive.)              affect the final choice.
                                                         Identification, development, and commercial-
• The World Bank assists developing coun-             ization of alternatives to ODSs are going on con-
  tries with investment projects, country             stantly. For this reason it is important to seek
  programs, workshops, training, and institu-         information on the latest alternatives from the
  tional strengthening.                               World Bank’s Global Environment Coordination
• The United Nations Environment Programme            Division. Technological updates are provided by
  (UNEP) has a clearinghouse function that in-        the World Bank’s Ozone Operations Resource
  cludes information exchange, country pro-           Group, which is made up of experts in halons,
  grams, training, and workshops.                     solvents, aerosols, refrigerants, mobile air con-
• The United Nations Development Programme            ditioning, foam blowing, and chemical produc-
  (UNDP) is responsible for feasibility and           tion. For any alternative, consideration needs to
252   PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES


be given to, for example, its compatibility with           Rigid polyurethane for other appliances. Alterna-
existing equipment, its health and safety aspects,      tives include HCFC-141b, HCFC-22, blends of
its direct global-warming potential, whether it in-     -22 and HCFC-142b, pentane, and carbon diox-
creases or decreases energy consumption, and the        ide/water blowing. In the long term, the alter-
costs that may be incurred in eventual conversion       natives include HFCs.
to a non-ODS technology if an interim HCFC al-
ternative is chosen. New ways of doing business            Rigid polyurethane used for boardstock and flex-
may also develop in the course of review and se-        ible-faced laminations. Alternatives include HCFC-
lection of alternatives. For example, many elec-        141b and pentane; in the long term, the use of
tronics companies have now converted their              HFCs should be developed.
manufacturing plants to “no-clean” technology.
The benefits include elimination of circuit board          Sandwich panels of rigid polyurethane. HCFC-
cleaning after soldering, savings in chemical costs     141b, HCFC-22, blends of HCFC-22 and -141b,
and waste disposal costs, savings in maintenance        pentane, and HFC-134a are now used as alterna-
and energy consumption, improved product qual-          tives to CFCs in this application. In the long term,
ity, and advances toward new technologies such          HFCs and carbon dioxide/water will be the re-
as fluxless soldering. The selection of any alterna-    placement technologies.
tive should not be made in isolation from the fac-
tors listed above.                                         Spray applications of rigid polyurethane. Alterna-
                                                        tives currently in use for spray applications in-
Flexible and Rigid Foams                                clude carbon dioxide/water and HCFC-141b.
                                                        Long-term alternatives will be HFCs.
Zero-ODP alternatives are the substitutes of
choice in many foam-manufacturing applica-                 Slabstock of rigid polyurethane. Alternatives in-
tions. However, the use of HCFCs is sometimes           clude HCFC-141b; long-term alternatives include
necessary in order to meet some product specifi-        HFCs and carbon dioxide/water. Pentane may
cations. The viability of liquid hydrofluorocarbon      also be used.
(HFC) isomers in this industry remains to be
proved, and hydrocarbon alternatives need to be            Rigid polyurethane pipe construction. CFCs in this
better qualified, as well. The issues in these evalu-   application are being replaced by carbon dioxide/
ations are safety (toxicity and flammability), en-      water, HCFC-22, blends of HCFC-22 and -142b,
vironmental impact (generation of volatile              HCFC-141b, and pentanes. Long-term alternatives
organic compounds and global warming), prod-            will include HFCs and carbon dioxide/water. For
uct performance (insulating properties, confor-         district central heating pipes, pentane and carbon
mity to fire codes, and the like), cost and             dioxide/water are the preferred technologies.
availability, and regulatory requirements.
   The next sections summarize the alternatives            Polyurethane flexible slab. Many alternatives
for specific products of the foam manufacturing         now exist for flexible slab construction, includ-
sector. Because of the complexity of the industry       ing extended range polyols, carbon dioxide/
and the variety of products, the alternatives have      water, softening agents, methylene chloride,
been listed briefly as short-term and long-term         acetone, increased density, HCFC-141b, pentane,
options, without an elaboration of the merits of        and other alternative technologies such as accel-
each. Additional information is available in the        erated cooling and variable pressure. The long
1995 UNEP Technical Options Report for this             term will probably see the use of injected carbon
sector.                                                 dioxide and alternative technologies.

   Rigid polyurethane foams used in refrigerators and      Molded flexible polyurethane. The standard now
freezers. Alternatives include hydrocarbons (pen-       is carbon dioxide/water blowing.
tane) and HCFC-141b; long-term alternatives in-
clude HFCs (-134a, -245, -356, -365). Vacuum               Integral-skin polyurethane products. The current
panels may be used in the future.                       alternatives for these products include HCFC-22,
                                                                 Ozone-Depleting Substances: Alternatives   253


hydrocarbons, carbon dioxide/water, HFC-134a,            factory. Neither HC-600a nor HFC-134a is con-
pentanes, and HCFC-141b. The long-term alter-            sidered an alternative for retrofitting domestic
nate is expected to be carbon dioxide/water.             refrigeration appliances, but preliminary data
                                                         indicate that a combination of the two may be a
   Phenolic foams. Phenolic foams can now be             retrofit, or “servicing,” candidate.
made using HCFC-141b, hydrocarbons, injected
carbon dioxide, or HFC-152a instead of CFCs. In             Commercial refrigeration. Alternatives to CFCs for
the long term, HFCs may be the predominant               new commercial refrigeration equipment include
alternative.                                             HCFCs (including HCFC mixtures) and HFCs and
                                                         HFC mixtures. Retrofit of existing equipment is
  Extruded polystyrene sheet. Alternatives cur-          possible by using both HCFCs and HFCs, in con-
rently include HCFC-22, hydrocarbons, injected           junction with reduced charges and more efficient
carbon dioxide, and HFC-152a. In the long term,          compressors. Hydrocarbons are, to a small extent,
these same alternatives (except for HCFC-22) will        applied in hermetically sealed systems.
be used, along with possible use of atmospheric
gases.                                                      Cold storage and food processing. Although there
                                                         has been a return to the use of ammonia for some
   Extruded polystyrene boardstock. HCFC-22 and          cold storage facilities, there are safety issues, and
-142b and injected carbon dioxide are the current        some regulatory jurisdictions restrict its use. Other
alternatives. Long-term alternatives will be HFCs        alternatives to CFCs in cold storage and large
and injected carbon dioxide.                             commercial food preservation facilities include
                                                         HCFC-22 and HFC blends. Hydrocarbons and
   Polyolefins. Polyolefins are now manufactured         HCFC-22 will continue to be the favored alter-
using alternatives such as hydrocarbons, HCFC-           natives until equipment using other alternatives
22 and -142b, injected carbon dioxide, and HFC-          is developed; ammonia will be used in selected
152a. Hydrocarbons and injected carbon dioxide           applications.
will be long-term alternatives.
                                                            Industrial refrigeration. New industrial refrigera-
Refrigeration, Air Conditioning, and Heat Pumps          tion systems that are used by the chemical, petro-
                                                         chemical, pharmaceutical, oil and gas, and
Refrigeration technology has also been rapidly           metallurgical industries, as well for industrial ice
evolving. Immediate replacements for many ap-            making and for sports and leisure facilities, can
plications include hydrocarbons, HFCs, and               use ammonia and hydrocarbons as the refriger-
HCFCs. Some of these will also be candidates for         ant. Although the product base concerned is small,
long-term replacement of the currently used              existing CFC equipment can be retrofitted to use
CFCs. This section briefly describes the alterna-        HCFC-22, HFCs and HFC blends, and hydro-
tives that are available for specific refrigeration,     carbons.
air conditioning, and heat pump applications.
                                                            Air conditioning and heat pumps (air-cooled sys-
   Domestic refrigeration. Two refrigerant alterna-      tems). Equipment manufactured in this category
tives are predominant for the manufacture of new         generally uses HCFC-22 as the refrigerant. Al-
domestic refrigerators. HFC-134a has no ozone            ternatives under investigation include HFCs
depletion potential and is nonflammable, but it          and HCs (propane). The most promising of these
has a high global-warming potential (GWP). HC-           are the nonflammable, nontoxic HFC com-
600a is flammable, has a zero ODP, and has a             pounds, although there is more interest in pro-
GWP approaching zero. Other alternatives for             pane in various regions. HCFs have been
some applications include HFC-152a and binary            criticized for their global warming potential, but
and ternary blends of HCFCs and HFCs. Retro-             their total equivalent warming impact (TEWI),
fitting alternatives may include HCFC/HFC                a measure that combines GWP and energy effi-
blends, after CFCs are no longer available. How-         ciency. is equal to or lower than that of the other
ever, the results obtained so far are still not satis-   alternatives.
254   PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES


   Air conditioning (water chillers). HCFC-22 has        Electronics cleaning. Experience has confirmed
been used in small chillers, and CFC-11 and -12       that for most uses in the electronics industry,
have been used in large chillers that employ cen-     ozone-depleting solvents can be replaced easily
trifugal compressors. HFC blends are now be-          and, often, economically. A wide choice of alter-
ginning to be introduced to replace HCFC-22 in        natives exists. If technical specifications do not
small chillers; HCFC-123 and HFC-134a are the         require postsolder cleaning, no-clean is the pre-
preferred replacements for large units. Chillers      ferred technology. If cleaning is required, the use
that have used CFC-114 can be converted to use        of water-soluble chemistry has generally proved
HCFC-124 or can be replaced by HFC-134a               to be reliable. Water-soluble chemistry is not,
units.                                                however, suitable for all applications.

   Transport refrigeration. HCFC-22 and CFC-502          Precision cleaning. Precision cleaning applica-
have been the refrigerants of choice for transport    tions are defined as requiring a high level of clean-
refrigeration units, although some applications are   liness in order to maintain low-clearance or
using ammonia as the refrigerant. The alternatives    high-reliability components in working order. To
include various HFC blends.                           meet exacting specifications, the alternatives that
                                                      have been developed include solvent and
   Automotive air conditioning. The manufacturers     nonsolvent applications. Solvent options include
of new automobiles have chosen HFC-134a as the        alcohols, aliphatic hydrocarbons, HCFCs and their
fluid for air conditioning units, and retrofit kits   blends, and aqueous and semiaqueous cleaners.
are now available to allow older automobiles to       Nonsolvent options include supercritical fluid
convert to this alternative.                          cleaning (SCF), ultraviolet (UV)/ozone cleaning,
                                                      pressurized gases, and plasma cleaning.
   Heat pumps (heating-only and heat recovery).
New heating-only heat pumps use HCFC-22,                 Metal cleaning. Oils and greases, particulate
and this is expected to continue. HFC-134a is         matter, and inorganic particles are removed from
an alternative for retrofitting existing heat         metal parts prior to subsequent processing steps
pumps, and investigation into the use of am-          such as further machining, electroplating, paint-
monia for large-capacity heat pumps is continu-       ing. Alternatives to ozone-depleting solvents that
ing. Other alternatives being explored include        have been developed include solvent blends,
propane, other hydrocarbons, and hydrocarbon          aqueous cleaners, emulsion cleaners, mechani-
blends.                                               cal cleaning, thermal vacuum deoiling, and no-
                                                      clean alternatives.
Solvents, Coatings, Inks, and Adhesives
                                                         Dry cleaning. Several solvents exist to replace the
There now exist alternatives or sufficient quanti-    ozone-depleting solvents that have traditionally
ties of controlled substances for almost all appli-   been used by the dry cleaning industry. Perchlo-
cations of ozone-depleting solvents. Exceptions       roethylene has been used for over 30 years. Petro-
have been noted for certain laboratory and ana-       leum solvents, while flammable, can be safely used
lytical uses and for manufacture of space shuttle     when appropriate safety precautions are taken.
rocket motors. HCFCs have not been adopted on         They include white spirit, Stoddard solvent, hy-
a large scale as alternatives to CFC solvents. In     drocarbon solvents, isoparaffins, and n-paraffin.
the near term, however, they may be needed as         A number of HCFCs can also be used but should
transitional substances in some limited and           be considered only as transitional alternatives.
unique applications. The UNEP Solvents Tech-
nical Options Committee does not recommend               Adhesives. Methyl chloroform has been used
HCFC-141b as a replacement for methyl chloro-         extensively by the adhesives manufacturing in-
form (1,1,1-trichloroethane) because its ODP is       dustry because of its characteristics—it is nonflam-
three times higher. Alternatives for specific uses    mable and quick drying, and it does not contribute
of ozone-depleting solvents are described in this     to local air pollution—and its performance. One
section.                                              alternative for some applications is water-based
                                                                 Ozone-Depleting Substances: Alternatives   255


adhesives. Other alternatives include hot melt          Halons
adhesives; radiation-cured adhesives; high-solids
adhesives; one-part epoxies, urethanes, and natu-       Halon hand-held extinguishers (containing 1211).
ral resins in powder form; moisture-cured adhe-         These can be replaced, in most applications, by
sives; and reactive liquids.                            multipurpose dry chemical extinguishers.

   Coatings and inks. Improvements have been               Halon 1301 total flood systems. New and existing
made to water-based coatings, and these can be a        alternatives are available for most halon 1301 to-
substitute for ODS-based applications. Water-           tal flood systems. These alternatives include zero-
based coatings have been used in the following          ODP halocarbons, inert gas mixtures, and new
industries and manufacturing sectors: furniture,        water-based technologies (e.g., water mist). The
automotive electronics, aluminum siding, hard-          use of HCFCs and hydrobromofluorocarbons
board, metal containers, appliances, structural         (HBFCs) as alternatives is not encouraged, and
steel, and heavy equipment. Water-based inks are        perfluorocarbons (PFCs) should not be used in-
used successfully for flexographic and rotogravure      discriminately.
laminates. High-solids coatings are now used for
appliances, metal furniture, and a variety of con-      Nonmedical Inhalants, Aerosols, Sterilants,
struction equipment. Powder coatings are used for       and Carbon Tetrachloride Not Used as a Solvent
underground pipes, appliances, and automobiles.
Ultraviolet light/electron beam (UV/EB) cured           Nonmedical aerosol products. A variety of alterna-
coatings and inks have been in limited use over         tives to CFCs are used in nonmedical aerosol
the past 20 years, but their use is increasing. They    applications. Alternatives include hydrocarbons
are now used in flexographic inks and coatings,         (HCs); dimethyl ether (DME); compressed gases
wood furniture and cabinets, and automotive             such as carbon dioxide, nitrogen, and air; HCFC-
applications.                                           142b and -22; HFC-134a -152a, and -227ea; and
                                                        nonaerosol delivery means such as pump sprays,
   Aerosol solvent products. Methyl chloroform is       solid sticks, roll-ons, brushes, and the like. Be-
most often the solvent in aerosol applications, but     cause hydrocarbons, DME, and HFC-152a are
some CFC-113 has also been used. Most of these          flammable, there may be products in which they
applications can now be reformulated to avoid the       cannot be used. In a manufacturing plant where
use of ozone-depleting chemicals. With the excep-       they are used for aerosol products, appropriate
tion of water, methylene chloride, and some             safety precautions will be required.
HCFCs and non-ozone-depleting chlorinated sol-
vents such as trichloroethylene and perchloroeth-          Inhalant drug products. Some medical aerosol
ylene, all of the alternatives to aerosol-applied       products such as nasal preparations, local anes-
solvents are more flammable than the solvents           thetics, and antibiotics can be reformulated
they replace. Alternative means of delivering the       through the use of alternative propellants, me-
solvent can be considered.                              chanical pumps, and so on. However, finding suit-
                                                        able alternatives to the CFCs in metered dose
   Other solvent uses of CFC-113, methyl chloroform,    inhalers (MDIs) used by asthma sufferers has been
and carbon tetrachloride. Specialized applications of   a challenge. Alternatives that have been developed
ozone-depleting solvents include drying of com-         and proven to date include dry powder inhalers
ponents, film cleaning, fabric protection, manu-        and HFC-134a and -227.
facture of solid-fuel rockets, laboratory testing and
analysis, process solvents, and semiconductor              Sterilants. A gas mixture of 88% CFC-12 and 12%
manufacture. Some of these applications have            ethylene oxide (EO) has been used by the medical
been granted an exemption under the Montreal            community to sterilize equipment and parts. Re-
Protocol, but it is the consensus of the experts on     placement alternatives include steam sterilization;
the UNEP Solvents Technical Options Committee           100% EO; blends of carbon dioxide (10%) and EO
that alternatives will be developed for all these       (90%); formaldehyde; HCFC-124 (91.4%) and EO
specialized uses.                                       (8.6%); and other means such as gas plasma, chlo-
256   PROJECT GUIDELINES: POLLUTANT CONTROL TECHNOLOGIES


rine dioxide, ozone, and radiation. Ethylene ox-        Structural. Chemical alternatives include sulfuryl
ide is toxic, mutagenic, flammable, and explosive    fluoride and phosphine, as well as contact insec-
and is a suspected carcinogen. Its use must there-   ticides and rodenticides. Nonchemical alterna-
fore be carefully controlled.                        tives are the same as for commodity fumigation.

   Carbon tetrachloride (nonsolvent uses). Carbon    Progress in Eliminating Ozone-Depleting
tetrachloride (CTC) has been used as a feedstock     Substances
for the production of CFC-11 and –12. This appli-
cation will cease with the closing of CFC produc-    Significant progress has been made in eliminat-
tion operations. CTC is also used as a feedstock     ing ozone-depleting substances since the entry
and processing agent for some pharmaceuticals        into force of the Montreal Protocol in late 1987.
and agricultural chemicals and in the production     For example, in the aerosol industry, the use of
of chlorinated rubber. The establishment of an al-   ODSs has been reduced from 300,000 metric tons
ternative for each application will be found only    (t) globally in 1986 to 180,000 t in 1989 to, it is
through product-specific research.                   estimated, less than 80,000 t in 1992. In the re-
                                                     frigeration sector, use of CFC refrigerants in in-
Methyl Bromide                                       dustrial countries dropped from 862,000 t in 1986
                                                     to 302,000 t in 1993. Globally, CFC refrigerant use
Methyl bromide is used primarily as a fumigant.      decreased from 1,133,000 t in 1986 to 643,000 t in
Only 3.2% of the global sale of more than 75,000     1992. To help in managing the phase-out of ODS
tons in 1992 was for nonfumigant purposes, as a      refrigerants, a service industry has been estab-
feedstock for chemical synthesis. The greatest       lished in most countries that captures and puri-
part was used to treat soil, to fumigate durables    fies ODSs during the servicing of equipment. The
and perishables, and to fumigate structures and      removed ODSs are then used to service the on-
transport equipment. From a conservation per-        going needs of ODS-containing refrigeration and
spective, technology exists to control the release   cooling equipment until it has reached the end
of methyl bromide when treating soil and             of its useful life. In the fire protection sector, the
crops. Molecular sieves are shown to capture         focus has been on establishing halon banks to
the methyl bromide that otherwise would have         recondition and store halon that has been re-
been lost to the atmosphere after batch fumi-        moved from service and to make it available for
gation and to regenerate the methyl bromide          maintaining other installations that require con-
for use in subsequent batches. Alternatives to       tinued use of halon until suitable replacements
methyl bromide in each application area de-          are developed. The foam plastics industry has
scribed below.                                       progressed from a global CFC use of 267,000 t in
                                                     1986 to 133,000 t in 1993—a reduction of 50%, in
   Soil. Chemical alternatives include 1,3-          spite of a 45% increase in the size of the industry
dichloropropene, dazomet, chloropicrin, metam        during the same period. The phase-out of ozone-
sodium, and selective contact insecticides and       depleting solvents is well advanced in industrial
herbicides. Nonchemical alternatives include         countries, and users are drawing on stockpiled
crop rotation, organic amendments, steam, solar      solvents. In developing countries, CFC-113 use
heating, biological control agents, cultural prac-   has been largely halted, and production facilities
tices, and plant breeding.                           are shutting down. The use of methyl chloroform
                                                     is no longer increasing in these countries. Coun-
   Commodities. Chemical alternatives for crop       tries such as Malaysia, Thailand, and Turkey have
fumigation include phosphine and carbonyl sul-       dramatically reduced solvent use.
fide, as well as insecticides and rodenticides.         It is important to note that the commercial sup-
Nonchemical alternatives include irradiation,        ply chain has had a role to play in the speed of
controlled atmospheres utilizing nitrogen and        phase-out of ODSs. In many instances, custom-
carbon dioxide, and heat and cold.                   ers have asked their suppliers to implement a
                                                          Ozone-Depleting Substances: Alternatives   257


phase-out program. These requests may originate    to improve their environmental performance.
because of labeling and tax legislation such as    Manufacturers also understand that the dwin-
that implemented by the United States or because   dling supply of ODSs causes price increases that
the customer has an environmental policy in        will eventually make those products more expen-
place that commits it to encourage its suppliers   sive and less competitive.

								
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