United States
Environmental
Protection
Agency
Office of
Ftesearch and
Development
Washington DC 20460
National Risk
Management
Research Laboratory
Cincinnati OH 45268
Air Pollution
Prevention and Control
Division
Research Triangle Park NC 27711
EPA/600/F-95/010
June 1995
Stratospheric Ozone
Research on Replacement
Chemicals to Protect the
Earth's Fragile Ozone Layer
ENVIRONMENTAL EFFECTS OF OZONE DEPLETION
MAN-GENERATED
EMISSIONS
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Improved Technology for Environmental Protection
Impact Summary
The Air Pollution Prevention and Control Division
(APPCD) [formerly known as the AEEERL (Air and
Energy Engineering Research Laboratory)] of the U.S.
EPA (United States Environmental Protection Agency)
has identified promising new chemicals which do not
deplete the ozone layer as substitutes for ODSs (ozone
depleting substances) and for some of the industry-
identified replacements that have global warming
potentials.
Background
The Earth's stratosphere is a thin film which shields the
Earth's surface from potentially damaging UV-B (ultra-
violet-B) radiation. Ozone molecules located in the
stratosphere 12 to 31 miles (19 to 50 km) above the
Earth's surface block most of the sun's harmful UV-B
radiation. This protective layer is critical to the environ-
ment because both humans and natural ecosystems are
sensitive to changes in UV-B levels. Over the last 10
years, the protective capacity of this natural shield has
diminished due to compounds including CFCs (chlorof-
luorocarbons) and halons, generated by human activi-
ties, which migrate to the stratosphere and destroy the
ozone molecules. The chemical responsible for most of
the destruction is chlorine from CFCs. The oxygen
molecules which remain after the ozone is destroyed do
not block UV-B radiation, allowing UV-B to penetrate
through the stratosphere to the Earth's surface. The
enhanced UV-B levels at the Earth's surface may
substantially increase skin cancer and cataract cases
worldwide and may have adverse effects on the human
immune system. Sensitive terrestrial and marine
ecosystems may also be adversely affected including
reductions in phytoplankton that could alter the entire
aquatic food chain. EPA's SAB (Science Advisory
Board) confirmed the magnitude of these risks when it
determined in 1990 that stratospheric ozone depletion is
in the highest-risk environmental category. The follow-
ing excerpt from the SAB's report entitled "Reducing
Risk - Setting Priorities and Strategies for Environmental
Protection" provides its rationale for this determination:
"Because releases of chlorofluorocarbons and other
ozone-depleting gases are thinning the Earth's strato-
spheric ozone layer, more ultraviolet radiation is reach-
ing the Earth's surface, thus, stressing many kinds of
organisms."
Even if all the ODSs were phased out today, the de-
struction process and the resulting effects will continue
well into the next century due to the long atmospheric
lifetimes of these compounds. Figure 1 shows U.S uses
and quantities of ODSs for the 1986 base year.
55%
10
[3Refrigeration G!Sterilization QSolvents iSaOther (TTIFoams
Figure 1. Uses of CFCs - The Way It Was
1986 U.S. Use of CFCs = 286,000 Metric Tons
Percentage by Use Sector
As a result, the APPCD mitigation program has taken
the approach that cooperation with industry is an
important ingredient for any success. The program
sprang from an industry, university, and Government
meeting to discuss whether any Government action was
appropriate. As work proceeded, industry has been kept
informed and its advice solicited. This has led to formal
and informal cooperation on specific projects. Examples
of industry interaction include DuPont Chemical
Corporation's producing quantities of isomers of HFC-
236 for application testing; Exxon Chemical Company's
making new lubricants for use with new chemicals; and
Hussman's, General Electric's, General Motors', and
Copeland's providing equipment for testing.
Potential Program Impact
Recognizing the need for action, the World community
accelerated the phaseout of production of the fully
halogenated CFCs, added additional ODSs to the
regulated list, and scheduled complete manufacturing
phaseout of almost all ODSs. Figure 2 shows changes
in phaseout requirements to the original Montreal
Protocol (1987) for selected ODSs that have been made
through the London (1990) and Copenhagen (1992)
amendments.
Since ODSs are interwoven through the fabric of our
society and contribute to our high standard of living,
their replacements will impact the cost and effectiveness
of heating and cooling of buildings and vehicles, food
preservation, manufacturing processes, medical care,
and fire protection. APPCD recognized the importance
of this issue (the difficulty in finding cost-effective,
environmentally acceptable replacements for ODSs for
a number of applications) and in 1987, initiated an ODS
replacement evaluation program. Chemicals which, for
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Improved Technology for Environmental Protection
Table 1. Estimated 1990 World Use of CFC/HCFC Refrigerants
Use
Home Refrigerator/Freezers
Supermarket Cases
Cold Storage and Food Processing
Industrial Cooling
Air Conditioners and Heat Pumps
Chillers
Transport Refrigeration
Motor Vehicle Air Conditioning
'Includes usage other than chillers (e.g.,
Table
Refrigerant Major Applications
CFC-11 Chillers
CFC-12 Motor Vehicle Air
Conditioners
Refrigerators
Freezers
Supermarkets
CFC-11 4 Chillers
R502 Supermarkets
(CFC-115& Cold Storage
HCFC-22) Transport
HCFC-22 Heat Pumps
Transport
Industrial Process
Chemical
CFC-12
CFC-12
R-502
HCFC-22
CFC-12/R-502
HCFC-22
CFCs (various)
HCFC-22
HCFC-22
CFC-11
CFC-12
CFC-114
HCFC-22
HCFC-22
CFC-12/R-502
CFC-12
foam)
2. ODS Alternatives and their Concerns
Alternative
HCFC-123
HFC-245ca -245fa
HFC-245 blends
HFC-134a,-227ea,-227ca
HFC-152a, HFE-143a,
Hydrocarbons
HCFC-22 blends
HFC-245cb
HFC-152a blends
HFE-143a blends
HCFC-124
HFC-254cb
HFC-236ea, -236fa, -236cb
HCFC-22
HCFC-22 blends
HFC-125, -143a & their blends
HFC-32
HFC-32 blends
HFE-125
HFE-125 blends
HFC-134a
HFC-32 blends
HFC-227 blends
HFE-125 blends
HFE-143a blends
Metric Tons
9,500
34,000
21,500
6,000
28,500
25,000
5,000
13,000
137,000
8,500
2,300
8,000'
5,900
19,190
3,845
128,000
Concern
Phaseout
Slightly Flammable
Global Warming
Flammable
Phaseout
Slightly Flammable
Some Flammable
Some Flammable
Phaseout, Redesign
Flammable
Phaseout, Redesign
Phaseout
Global Warming
Flammable, Redesign
Global Warming
Global Warming, Redesign
Some Require Redesign
Global Warming
Some Require Redesign
Redesign
Some Require Redesign
Some Flammable
Legend: Green = APPCD chemical
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Improved Technology for Environmental Protection
Table 3. APPCD Evaluation of New Refrigerants Includes
Seven Characteristics
Thermal and Hydrolytic Stability
Lubricant Miscibility
Atmospheric Lifetime
Flammability
Materials Compatibility
Refrigeration Performance
Toxicity
lead to expanded utilization of the same refrigerant in
the public refrigeration sector and would help to speed
replacement of ozone-depleting substances.
Commercial chillers
Centrifugal water chillers are the primary means for air-
conditioning buildings over 40,000 square feet (3700
square meters). They account for about 75 percent of
the chiller-equipment stock and over 95 percent of the
CFC emissions from chillers. They use mainly CFC-11;
however, CFC-12, CFC-114, and HCFC-22 are also
used.
Among APPCD's new chemicals, HFC-245ca and HFC-
245fa appear promising as alternatives to CFC-11.
Currently, HCFC-123 is being used to replace CFC-11,
and HFC-134a is being used to replace CFC-12 al-
though concern about the latter's energy efficiency and
global warming potential stimulates the search for better
alternatives.
Comparative information for CFC-114 and CFC-11 with
APPCD's leading alternatives is shown in Tables 4 and
5, respectively.
Supermarket refrigeration:
For low-temperature systems, APPCD has identified
HFE-125 as having the best properties for performing as
a non-chlorinated refrigerant. Its atmospheric lifetime is
under evaluation and will directly affect global warming
potential.
At the high end of the low-temperature systems (e.g.,
unit freezers), another APPCD candidate, HFE-143a,
has acceptable thermodynamic characteristics, and its
energy efficiency is expected to be better than industry's
alternatives.
Heat pumps and air conditioners:
Currently, no single refrigerant has been identified that
performs as well as HCFC-22 in heat pumps and air
conditioners. However, a number of refrigerant blends
have been shown to offer promise for replacing HCFC-
22. These replacements have to meet several important
requirements including capacity, efficiency, nonflamma-
bility, compatibility with lubricants and materials,
commercial producibility, and cost effectiveness.
APPCD's new chemicals include several that potentially
can be used in blends with other commercially available
chemicals to improve performance in refrigeration
equipment.
Refrigerator/freezers:
An effort is being made to find near-drop-in replace-
ments for CFC-12 for utilization in refrigerator/ freezers
of developing countries. The objectives are both to have
developing countries choose not to use the additional 10
years given to them to halt the use of CFCs in refrigera-
tion equipment and to provide a cost-effective transition
to environmentally friendly refrigerants. India (population
900 million) produces a million refrigerators annually
with approximately 7.5 million presently in service. For
1990 through 1994, the production rate is expected to
average 2 million refrigerators per year. Any major and
costly retrofitting to utilize non-chlorine alternatives will
deeply affect India's economy and be a severe hardship
on the people. Similar consequences are expected in
other developing countries. Finding near- drop-in
replacements that are more energy efficient will reduce
equipment modification expense and will be environ-
mentally advantageous.
The leading candidate for new refrigerator/freezers is
HFC-134a. However, since HFC-134a has substantial
global warming potential and may ultimately need to be
replaced, APPCD's new chemicals are being evaluated
as potential long-term replacements.
Foam blowing:
Efforts to replace CFC blowing agents in foam insulation
products have resulted in the development of drop-in
HCFC substitutes which have significantly lower ozone
depletion potential than CFCs. HCFCs are only interim
replacements since they also contribute to the depletion
of the ozone layer and will themselves also be phased
out of use.
There is a strong need to find chemicals which do not
cause ozone depletion in the stratosphere as substitutes
for blowing agents used in production of plastic foam
insulating materials.
The ongoing APPCD study has identified and catego-
rized a large group of novel compounds as candidates
for CFC substitutes for a wide array of uses. As a result
of this effort, several new chemicals identified by
APPCD (HFCs -236ea, -245ca, and -245fa) were
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Table 4. Comparison of CFC-114 with Alternatives
Current Chemical APPCD Candidate Replacements
CFC-114 HFC-236ea HFC-236fa
Boiling Point (K)
Flammability
Toxicity (Lethal Concentration50,ppm)
Atmospheric Lifetime (years)
Global Warming Potential**
Ozone Depletion Potential
Refrigeration Performance (COP***)
277.0
no
>200,000
220*
5800*
1.0
6.26
279.7
no
30,000x100,000
7.8
115
0.0
6.23
272.1
no
>200,000
200
6800
0.0
6.02
= From IPCC (International Panel on Climate Change) Supplementary Report 1992
= Based on CO2 with 500 year horizon
= Coefficient of Performance
Table 5. Comparison of CFC-11 with Alternatives
Current Chemical APPCD Candidate Replacements
CFC-11 HFC-245ca HFC-245:a
Boiling Point (K)
Flammability
Toxicity (Lethal Concentration^, ppm)
Atmospheric Llifetime (years)
Global Warming Potential**
Ozone Depletion Potential
Refrigeration Performance (COP***)
297.0
no
27,000
55*
1400*
1.0
6.93
298.2
marginal
?(but>1000)
=7
190
0,0
6.55
288.5
marginal
10
•?
0.0
6.59
= From IPCC (International Panel on Climate Change) Supplementary Report 1992
= Based on CO2 with 500 year horizon
= Coefficient of Performance
recommended as potential new foam blowing agents
and are currently being investigated by industry.
Fire Protection:
Because halons were effective, they were used for
some applications where they were not necessary.
However, there are applications where their characteris-
tics were necessary. For these applications, APPCD
participated in an investigation in cooperation with the
North Slope Oil Producers to evaluate alternatives for
fire protection and explosion inertion for their oil and gas
handling facilities. The results produced a large data
base on different agents. Although some had promise,
the conclusion was that the next step should be evalua-
tion of a different class of chemicals, fluoroiodocarbons.
Since funding for the next phase from non-EPA sources
was adequate, industry continued without EPA participa-
tion. These results have shown that fluoroiodocarbons
are effective fire protection agents, and both industry
and the Department of Defense continue to evaluate
them.
Accomplishments
APPCD has identified and characterized unique replace-
ment chemicals for fully halogenated CFCs. An array of
chemicals that might be used in mixtures has been
identified for replacement of the leading HCFCs and for
some of the industry-identified ODS replacements that
have global warming concerns. The data are being used
by industry as decisions are made on which paths to
pursue.
The APPCD program has shown the foresight to ad-
dress the potential long-term needs of a stratospheric
ozone protection replacement program. Also, APPCD
has recognized that some of the second-generation
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replacement chemicals have high global warming
potential and may be acceptable only for an interim
period. Chemicals which APPCD is developing have the
potential to replace these second-generation chemicals
with more environmentally acceptable substitutes.
The APPCD program has encouraged aggressive efforts
for impacted industries. This research has provided U.S.
industry with a significant head start in developing and
ultimately commercializing new replacement chemicals.
Also, APPCD's accomplishments have assisted
policymakers in pursuing an aggressive phaseout
program while simultaneously assisting industry in
developing sound phaseout decisions.
The Navy is a particular beneficiary of this work. Selec-
tion of one of the two primary CFC-114 alternatives will
allow efficient retrofit of the existing fleet with Navy
estimates of over $500 million in savings.
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