TRANSITIONING TO LOW-GWP ALTERNATIVES
IN TRANSPORT REFRIGERATION
Background
This fact sheet provides current information on low-Global Warming
Potential (GWP) refrigerant and foam blowing agent alternatives used
in transport refrigeration equipment, relevant to the Montreal Protocol
on Substances that Deplete the Ozone Layer. The transport refrigeration
sector primarily moves perishable goods (i.e., food), and to a lesser
extent pharmaceutical products, at temperatures between -30° C and
16° C, by various modes of transportation, including road, rail, ships,
and intermodal containers. The text box (right) describes these modes
of transportation in more detail. The transport refrigeration sector has
special requirements in terms of equipment reliability and durability to
guarantee product quality and personnel safety.
The expected lifetime for road vehicles, railcars, and intermodal containers
is between 10 and 15 years, and between 20 and 25 years for equipment
aboard ships. Refrigerant charge size varies based on mode of transport,
typically between 4.5 and 7.5 kg for road vehicles, railcars, and intermodal
containers and 100 to 500 kg for conventional equipment aboard ships.
In addition to refrigerant, transport refrigeration equipment also contains
insulating foam. Commonly used foam types include polyurethane
(PU) injected pipe-in-pipe foam, PU rigid panels (continuous and
discontinuous), block, and extruded polystyrene (XPS) board foam.The
typical foam density in intermodal containers is high, ranging from 40
to 45 kg/m3, to maintain temperatures over long distances and time
periods. Hold sizes on refrigerated ships are often 25-35% smaller than
equivalent-sized non-refrigerated cargo ships, due to the thickness of the
PU foam insulation required for the refrigerated systems.
Because demand for MFCs in refrigeration and air conditioning
equipment is increasing, particularly in developing countries, HFC
emissions could rise to as much as 19% of projected global C02
emissions by 2050 if left unchecked. In 2010, the transport refrigeration
sector accounted for about 9% of global HFC consumption in the
refrigeration/AC sector—approximately 80 million metric tons of
carbon dioxide equivalent (MMTC02eq.)—or approximately 7% of HFC
consumption across all sectors. Developing countries' use of HFCs in
the transport refrigeration end-use accounted for approximately 3% of
Modes of Transportation in
the Transport Refrigeration Sector
Intermodal Containers—refrigerated containers allow
uninterrupted storage during transport on different mobile
platforms, including railways, road trucks, and ships.
Rail—refrigerated railcars, mainly used for long distances,
account for only a small share of total refrigerated transport,
gradually being replaced by intermodal containers.
Road—refrigerated vans, trucks, or trailer-mounted systems are
the most common mode of refrigerated transport, with an estimated
4 million vehicles in operation worldwide in 2009 (of which 30%
were trailers, 30% large trucks, and 40% small trucks/vans).
Ships—refrigerated ships and marine branches, including
merchant, naval, fishing and cruise-shipping, are commonly used
to transport perishable goods.
the global HFCs consumed as refrigerants within the refrigeration/AC
sector, and 38% of global HFCs consumed as refrigerants in the transport
refrigeration end-use specifically.
HFC Alternatives and Market Trends
Historically, the main refrigerant in the transport refrigeration sector was
HCFC-22, although other ODS were also used (e.g., R-502, CFC-12). In
response to the global ODS phaseout, many equipment manufacturers
in developed countries converted to HFCs in the 1990s—primarily to
R-404A, R-507A, R-410A, R-407C, and HFC-134a—because these were
the most widely available and studied options at the time. By 2010, global
market penetration of HFC refrigerants in the installed base of transport
refrigeration equipment was estimated at 40% for ships, 70% for road
vehicles, and 95% for intermodal containers. Over time, low-GWP options
began to enter the market; the transition to low-GWP alternatives, such
as ammonia (R-717) or carbon dioxide (R-744, CO ), has begun in some
2010 HFC Consumption
(Estimates Presented in MMTCO eq.)
Transport Refrigeration
Developed Countries
(1%)
Solvents
(1%)
Fire Extinguishing
(4%)
Transport Refrigeration
Developed Countries
(6%)
Transport Refrigeration
Developing Countries
(3%)
Transport Refrigeration
Developing Countries
<
Global HFC Consumption Foams Sector Total: 124 MMTC02eq.
Global HFC Consumption Foams Sector Transport Ref.: 2 MMTCO eq.
Global HFC Consunption Total: 1,087 MMTC02eq.
Global HFC Consumption Transport Ref.: 82 MMTCO eq.
Global Consumption Ref/AC Sector Total: 858 MMTC02eq.
Global Consumption Ref/AC Sector Transport Ref.: 80 MMTCO eq.
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transport refrigeration end-uses. For example, R-717 and R-744 are used
in refrigerated ships, accounting for nearly 5% of the installed global
market in 2010. R-744 is also being considered as an alternative for
intermodal containers. Hydrocarbons (HCs) and liquid R-744, as well as
alternative technologies—cryogenic (open-loop) systems, secondary loop
systems, eutectic places, hermetic/semi-hermetic systems, and cascade
systems—are under limited use or are being explored for use in road
vehicles. Combinations of stationary HCs or R-717 with liquid R-744, as
well as alternative technologies (e.g., eutectic plates), are being explored
for refrigerated railcars. In addition, HFOs1 are also being researched
and developed and may become available for use across the various
transportation modes in future.
Foam insulation in transport refrigeration traditionally used CFC-11
and HCFC-141b blowing agents. Over 50% of foams in this sector are
manufactured in developing countries, with China being a dominant
manufacturer of reefers. In response to the global ODS phase out,
developed countries have transitioned to substitute blowing agents.
Europe transitioned to HCs, and North America and Japan transitioned
largely to HFCs, including HFC-245fa and HFC-365mfc/HFC-227ea
blends. In developing countries, HCFCs (primarily HCFC-141b) continue
to be used, although some HFCs have been adopted in Latin America.
In addition to HCs, other low-GWP alternatives are being explored,
including methyl formate and low-GWP fluorinated compounds.
Norway's Experience
In 2007, liquid C02 refrigerant-based cryogenic systems were
introduced into Norway's road transport refrigeration market.
Cryogenic truck and trailer systems use liquid C02 for refrigeration
to minimize environmental impact and noise while providing high
reliability and lower maintenance.
In 2011, approximately 16% of new refrigerated truck and trailer
systems sold in Norway were equipped with cryogenic refrigeration
systems. One of Norway's largest food distributors has committed
to making cryogenic system-equipped vehicles the standard for
all of their future purchases. In addition, a major manufacturer
of cryogenic systems has partnered with one of Norway's largest
refrigerant suppliers to provide C02 filling stations across the
country. Cryogenic systems are currently used in other European
countries (e.g., Sweden, Denmark, Finland, France, the Netherlands,
and Germany), and are being piloted in the United States. Use of
liquid C02 refrigerant-based cryogenic systems is expected to expand
further in the future, particularly in Western Europe.
Alternative Refrigerants
• R-744
o Limited use in refrigerated ships and road applications; under evaluation for use in
intermodal containers and in combination with HCs or R-717 for rai applications
o Carrier Transicold announced production of high-efficiency R-744 refrigerated
marine containers; demonstration units are being tested in various locations
worldwide, including the United States and Singapore
o Use in compression systems (including hermetic/semi-hermetic compressors) likely
to be enabled in road transport if/when refrigeration equipment becomes electrified
o Solid R-744 used in some small containers and boxes; requires external mechanical
refrigeration system to generate
• R-717
o Limited application in indirect and cascade systems on new refrigerated ships;
specifically in ships that carry professional crew only (no passengers) and those
with relatively high refrigeration capacity (e.g., fishing ships)
o Under evaluation for use in refrigerated railcars
• HCs (isobutane, propane)
o Under evaluation for use in road or rail transport refrigeration (in secondary
loop systems)
o Use in compression systems (including hermetic/semi-hermetic compressors) likely
to be enabled in road transport if/when refrigeration equipment becomes electrified
• HFOs (e.g., HFO-1234yf,2 blends)
o Under consideration for use across transport refrigeration modes beyond 2014,
particularly road
Alternative Refrigerant Technologies
• Cryogenic (Open-Loop) Systems
o Cryogenic (open-loop) systems cool cargo by injection of stored liquid R-744 or
nitrogen (R-728, N2) to the cargo space or an evaporator
o Used in small and large trucks, primarily in northern Europe
o Low noise, reduced maintenance, and strong refrigeration performance
Chemical
GWP
OOP
Refrigerant
R-12
R-502
R-507A
R-404A
R-41 OA
R-22
R-407C
R-134a
R-1234yf
R-290 (Propane)
R-600a (Isobutane)
R-744 (C02)
R-717 (Ammonia)
R-728 (Nitrogen)
10,900
4,657
3,985
3,922
2,088
1,810
1,774
1,430
4
3.3
3
1
0
0
1
0.334
0
0
0
0.055
0
0
0
0
0
0
0
0
Blowing Agent
CFC-1 1
HFC-227ea
HCFC-22
HFC-245fa
HFC-365mfc
HCFC-141b
Cyclopentane
n-Pentane
Methyl Formate
Methylal
Isopentane
FEA-1 1 00
HBA-2
HFO-1 234ze
Isobutane
4,750
3,220
1,810
1,030
794
725
<25
<25
<25
<25
11
9.4
7
6
3
1
0
0.055
0
0
0.11
0
0
0
0
0
0
~0
0
0
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• Secondary Loop Systems
o Systems chill an intermediate fluid, which is circulated from the
refrigerant-containing equipment to the areas to be cooled
o Under evaluation for use in road transport refrigeration applications
o Reduces concern of leaks and flammability associated with use of
some refrigerants (e.g., HCs, R-717)
• Eutectic Plates
o Based on a frozen salt solution which removes heat from the
environment as it melts and provides refrigeration; they must be
periodically regenerated by freezing in an external mechanical
refrigeration system
o Limited use in conjunction with standard cooling systems (with
reduced refrigerant charge) for short distance distribution,
particularly of frozen products, in road transport and intermodal
container applications and explored for rail transport applications
• Hermetic/Semi-Hermetic Vapor Compression Systems
o May be used in place of open-drive compressors to enable use of
low-GWP refrigerants that are high pressure or flammable
(e.g., transcritical R-744, HCs)
o Currently being tested in road transport refrigeration applications
in North America and Europe
• Cascade Systems
o Currently used on refrigerated transport ships, using R-717, R-744,
or combination of R-717/HCs/HFCs
o Systems combining vapor compression cycle and heat-driven
adsorption equipment under development for refrigerated trucks
The actual and potential transition to these alternatives in transport refrigeration applications is illustrated in the diagrams below.3
Refrigerant Transition in the Transport Refrigeration End-Use
Alternative Foam Blowing Agents
• HCs (e.g., cyclopentane, n-pentane)
o Provides greater gas pressure in foam cell and allows reduced
foam density
o Production process for handling flammable agents required
o Used in intermodal containers, refrigerated ships, and truck bodies
o Under consideration for use in railcars (co-blown with MFCs or HFOs)
• Methyl Formate
o Under evaluation for use in road transport applications
• Methylal
o Under early evaluation as a co-blowing agent with HCs and MFCs in
rigid foams in rail applications; possibly in future for road and ship
applications as well
• Low-GWP Fluorinated Compounds (e.g., HFO-1234ze, HBA-2,
FEA-1100)
o Non-flammable
o Good solubility properties
o Under evaluation for intermodal containers, rail applications, and
particularly in truck bodies
o Liquid HFOs as replacements for HFC-245fa and HFC-365mfc may
become available after 2014
*-
-12.R-50;
Refrigerant
Options:
R-744
Road, Ships, Containers, Rail
Ships, Rail
Rail, Road
HFOs
Containers, Rail, Road, Ships
Technology Cryogenic
Options: Systems
Road
lecondary
Loop Systems
Road
Eutectic Pla
"^^
Containers, Road, Rail
(Semi)-Hermetic
Systems
Road
ade Systems
Ships, Road
CFC-11
Blowing Agent Transition in the Transport Refrigeration End-Use
HCFC-141b ->• HFCs m~
Containers, Road, Ships, Rail
lethyl Formate
Road
»— 2£S
Rail, Road, Ships
Fluorinated
Compounds
Containers, Rail, Road
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Challenges to Market Entry and Potential Solutions
The following table summarizes the challenges associated with the adoption of various alternatives as well as potential solutions to overcoming
the challenges.
Alternative
Mode of Transportation
Challenges to Market Entry
Potential Solutions
Alternative Refrigerants
R-744
R-717
HCs
HFOs
• Intermodal Containers
• Rail
• Road
• Ships
• Rail
• Ships
• Rail
• Road
• Intermodal Containers
• Rail
• Road
• Ships
• Safety Risks
• High Operating Pressure
• Toxicity
• Slight Flammability
• High Flammability
• Liability Concerns
• Safety Code Restrictions
• Slight Flammability
• Engineering Design
• Test Procedures
• Training and Education
• Engineering Design
• Standards and Safety Regulations
• Safety Devices
• Standards and Service Procedures
• Training and Education
• Research and Development
Alternative Refrigerant Technologies
Cryogenic Systems
Secondary Loop Systems
Eutectic Plates
Hermetic/Semi-Hermetic
Compression Systems
Cascade Systems
• Road (small and large trucks)
• Road
• Intermodal Containers
• Rail
• Road
• Road (HC/R-744 systems)
• Road
• Ships
• Complex Safety Mechanisms
• Requires Recharging with Liquid Coolant at Stops
• Limited Experience
• Technical Constraints; Periodic Regeneration
Through External Freezing Necessary
• Complex Safety Mechanisms
• Limited Experience
• Requires System Calibration
• Engineering Design
• Research and Development
• Research and Development
• Engineering Design
• Research and Development
• Engineering Design
• Research and Development
• Engineering Design
• Research and Development
Alternative Foam Blowing Agents
HCs
Methyl Formate
Methylal
Low-GWP Fluorinated
Compounds
• Intermodal Containers
• Rail
• Road
• Ships
• Road
• Rail
• Road
• Ships
• Road
• Rail
• Intermodal Containers
• High Flammability
• Lower Thermal Performance
• Limited Experience
• Slight Flammability
• Uncertainty About Long Term Physical Properties,
Including Insulation
• Limited Experience as the Sole Blowing Agent
• Market Availability
• Engineering Design and Pre-Blending
• Research and Development
• New Equipment Required to Handle
Flammable Agents
• Engineering Design
• Research and Development
• Research and Development
• Research and Development
Future Outlook
Many transport refrigeration applications have readily available, low-GWP foam blowing agent and refrigerant alternatives that will be adopted
as HCFCs are phased out. However, in the case of some applications, such as foam in refrigerated railcars, continued research and development
are needed to identify and commercialize technically feasible, low-GWP alternatives. Together, the suite of known alternative chemicals and new
technologies can significantly reduce HFC consumption in both the near and long term, while simultaneously completing the HCFC phaseout. Although
much work remains to fully adopt these chemicals and technologies, and some unknowns still remain, the industries currently using HCFCs and HFCs
have proven through the ODS phaseout that they can move quickly to protect the environment.
1 HFOs (hydrofluoro-olefins) are unsaturated HFCs.
2 HFO-1234yf refrigerant is also commonly referred to as HFC-1234yf or R-1234yf, as it is referred to in the remainder of this fact sheet.
3 For all diagrams, non-italicized font represents alternatives previously used or currently available in the market for the given transport
mode; italicized font indicates those likely to be available in the future.
vvEPA
U.S. Environmental Protection Agency
EPA-430-F-11-064 • www.epa.gov • October 2011
Printed on 100% recycled/recyclable paper with a minimum
50% post-consumer waste using vegetable-based inks
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