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 -30o C and 

16o 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 HFCs in refrigeration and air conditioning 

equipment is increasing, particularly in developing countries, HFC 

emissions could rise to as much as 19% of projected global CO2

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 (MMTCO2eq.)—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 

TRANSITIONING TO LOW-GWP ALTERNATIVES 

IN TRANSPORT REFRIGERATION

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.

2010 HFC Consumption

(Estimates Presented in MMTCO2eq.)

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, CO2), has begun in some 

Fire Extinguishing

(4%)

Solvents

(1%)

Transport Refrigeration

Developing Countries 

(3%) Transport Refrigeration

Developing Countries 

(<1%)

Transport Refrigeration 

Developed Countries 

(6%)

Transport Refrigeration

Developed Countries 

(1%)

Aerosols

(5%)

Ref/AC 

(79%)

Other

Foams

(99%)

Other 

Ref/AC

(91%)

Foams 

(11%)

Global HFC Consumption Foams Sector Total: 124 MMTCO2eq.

Global HFC Consumption Foams Sector Transport Ref.: 2 MMTCO2eq. Global HFC Consumption Total: 1,087 MMTCO2

eq.

Global HFC Consumption Transport Ref.: 82 MMTCO2eq.

Global Consumption Ref/AC Sector Total: 858 MMTCO2eq.

Global Consumption Ref/AC Sector Transport Ref.: 80 MMTCO2eq.
Chemical GWP ODP

Refrigerant

R-12 10,900 1

R-502 4,657 0.334

R-507A 3,985 0

R-404A 3,922 0

R-410A 2,088 0

R-22 1,810 0.055

R-407C 1,774 0

R-134a 1,430 0

R-1234yf 4 0

R-290 (Propane) 3.3 0

R-600a (Isobutane) 3 0

R-744 (CO2) 1 0

R-717 (Ammonia) 0 0

R-728 (Nitrogen) 0 0

Blowing Agent

CFC-11 4,750 1

HFC-227ea 3,220 0

HCFC-22 1,810 0.055

HFC-245fa 1,030 0

HFC-365mfc 794 0

HCFC-141b 725 0.11

Cyclopentane <25 0

n-Pentane <25 0

Methyl Formate <25 0

Methylal <25 0

Isopentane 11 0

FEA-1100 9.4 0

HBA-2 7 ~0

HFO-1234ze 6 0

Isobutane 3 0

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 CO2 refrigerant-based cryogenic systems were 

introduced into Norway’s road transport refrigeration market. 

Cryogenic truck and trailer systems use liquid CO2 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 CO2 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 CO2 refrigerant-based cryogenic systems is expected to expand 

further in the future, particularly in Western Europe.

Alternative Refrigerants 

•	 R-744

m Limited use in refrigerated ships and road applications; under evaluation for use in 

intermodal containers and in combination with HCs or R-717 for rail applications

m 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 

m Use in compression systems (including hermetic/semi-hermetic compressors) likely 

to be enabled in road transport if/when refrigeration equipment becomes electrified 

m Solid R-744 used in some small containers and boxes; requires external mechanical 

refrigeration system to generate 

•	 R-717

m 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) 

m Under evaluation for use in refrigerated railcars 

•	 HCs (isobutane, propane) 

m Under evaluation for use in road or rail transport refrigeration (in secondary 

loop systems) 

m 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)

m Under consideration for use across transport refrigeration modes beyond 2014, 

particularly road

Alternative Refrigerant Technologies 

•	 Cryogenic (Open-Loop) Systems

m 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

m Used in small and large trucks, primarily in northern Europe 

m Low noise, reduced maintenance, and strong refrigeration performance
•	 Secondary Loop Systems

m Systems chill an intermediate fluid, which is circulated from the 

refrigerant-containing equipment to the areas to be cooled 

m Under evaluation for use in road transport refrigeration applications

m Reduces concern of leaks and flammability associated with use of 

some refrigerants (e.g., HCs, R-717)

•	 Eutectic Plates

m 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 

m 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 

m 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) 

m Currently being tested in road transport refrigeration applications 

in North America and Europe

•	 Cascade Systems

m Currently used on refrigerated transport ships, using R-717, R-744, 

or combination of R-717/HCs/HFCs

m Systems combining vapor compression cycle and heat-driven 

adsorption equipment under development for refrigerated trucks 

Alternative Foam Blowing Agents 

•	 HCs (e.g., cyclopentane, n-pentane) 

m Provides greater gas pressure in foam cell and allows reduced 

foam density

m Production process for handling flammable agents required 

m Used in intermodal containers, refrigerated ships, and truck bodies 

m Under consideration for use in railcars (co-blown with HFCs or HFOs)

•	 Methyl Formate 

m Under evaluation for use in road transport applications

•	 Methylal

m Under early evaluation as a co-blowing agent with HCs and HFCs 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) 

m Non-flammable

m Good solubility properties

m Under evaluation for intermodal containers, rail applications, and 

particularly in truck bodies

m Liquid HFOs as replacements for HFC-245fa and HFC-365mfc may 

become available after 2014

Refrigerant Transition in the Transport Refrigeration End-Use

Blowing Agent Transition in the Transport Refrigeration End-Use

The actual and potential transition to these alternatives in transport refrigeration applications is illustrated in the diagrams below.3

CFC-11 HCFC-141b HFCs

Methyl Formate

Road

Methylal

Rail, Road, Ships

HCs

Containers, Road, Ships, Rail

Fluorinated 

Compounds

Containers, Rail, Road

R-744 R-717 HCs HFOs

R-12, R-502 R-22 HFCs

Refrigerant 

Options:

Technology 

Options:

Road, Ships, Containers, Rail Ships, Rail Rail, Road

(Semi)-Hermetic 

Systems

Road

Cryogenic 

Systems

Road

Containers, Rail, Road, Ships 

Eutectic Plates

Containers, Road, Rail

Cascade Systems

Ships, Road

Secondary 

Loop Systems

Road
Alternative Mode of Transportation Challenges to Market Entry Potential Solutions

Alternative Refrigerants

R-744 •	Intermodal Containers

•	Rail

•	Road

•	Ships

•	Safety Risks

•	High Operating Pressure

•	Engineering Design

•	Test Procedures

•	Training and Education

R-717 •	Rail

•	Ships

•	Toxicity

•	Slight Flammability

•	Engineering Design

•	Standards and Safety Regulations

HCs •	Rail

•	Road

•	High Flammability

•	Liability Concerns

•	Safety Code Restrictions

•	Safety Devices

•	Standards and Service Procedures

•	Training and Education

HFOs •	Intermodal Containers

•	Rail

•	Road

•	Ships

•	Slight Flammability •	Research and Development

Alternative Refrigerant Technologies

Cryogenic Systems •	Road (small and large trucks) •	Complex Safety Mechanisms

•	Requires Recharging with Liquid Coolant at Stops

•	Engineering Design

•	Research and Development

Secondary Loop Systems •	Road •	Limited Experience •	Research and Development

Eutectic Plates •	Intermodal Containers 

•	Rail

•	Road

•	Technical Constraints; Periodic Regeneration 

Through External Freezing Necessary

•	Engineering Design

•	Research and Development

Hermetic/Semi-Hermetic 

Compression Systems

•	Road (HC/R-744 systems) •	Complex Safety Mechanisms •	Engineering Design

•	Research and Development

Cascade Systems •	Road

•	Ships

•	Limited Experience

•	Requires System Calibration

•	Engineering Design

•	Research and Development

Alternative Foam Blowing Agents

HCs •	Intermodal Containers

•	Rail

•	Road

•	Ships

•	High Flammability

•	Lower Thermal Performance

•	Engineering Design and Pre-Blending

•	Research and Development 

•	New Equipment Required to Handle 

Flammable Agents

Methyl Formate •	Road •	Limited Experience

•	Slight Flammability 

•	Uncertainty About Long Term Physical Properties, 

Including Insulation

•	Engineering Design

•	Research and Development

Methylal •	Rail

•	Road

•	Ships

•	Limited Experience as the Sole Blowing Agent •	Research and Development

Low-GWP Fluorinated 

Compounds

•	Road

•	Rail

•	Intermodal Containers

•	Market Availability •	Research and Development

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.

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.

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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