REFRIGERATION AND GLOBAL WARMING
An Independent Review of the Role of HFC Refrigerants
by March Consulting Group
prepared for the European Fluorocarbon Technical Committee,
a Sector Group of CEFIC
September 1997
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CONTENTS
SUMMARY ............................................................................................................................... 1
1. INTRODUCTION .................................................................................................................. 2
PART A BACKGROUND TO REFRIGERATION AND REFRIGERANTS
2. REFRIGERATION APPLICATIONS .................................................................................. 3
3. SELECTING REFRIGERANTS ........................................................................................... 5
PART B BACKGOUND TO GLOBAL WARMING ISSUES
4. THE IMPACT OF REFRIGERATION ON GLOBAL WARMING .................................... 8
5. INTERNATIONAL EFFORTS TO REDUCE GLOBAL WARMING IMPACT .............. 10
PART C ANALYSIS OF GW IMPACT OF REFRIGERATION
6. OPPORTUNITIES TO REDUCE THE GW IMPACT OF REFRIGERATION ................ 11
7. DIRECT EMISSION REDUCTION OPPORTUNITIES.................................................... 12
8. ENERGY EFFICIENCY OPPORTUNITIES ...................................................................... 14
9. SAFETY ISSUES ................................................................................................................ 16
10. END USE SECTOR REVIEW .......................................................................................... 18
11. HISTORICAL AND FUTURE GLOBAL WARMING IMPACT.................................... 22
APPENDIX 1 GLOSSARY OF TERMS …………………………………………………...25
APPENDIX 2 REFERENCES ………………………………………………………………26
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SUMMARY
1. This report presents a review of alternative options for refrigerants and examines
ways in which the future global warming impact of refrigeration can be minimised.
2. The report was prepared by March Consulting Group at the request of the
European Fluorocarbon Technical Committee during August/September 1997.
3. There is excellent potential for the refrigeration and air-conditioning user sectors
to make a very positive contribution to solving the major environmental problem
of global warming. The following figures show the global warming impact of EU
refrigeration and air-conditioning systems expressed in Mtonnes CO2 equivalent.
1990 actual
2010 forecast
% reduction
Direct Impact
200
30
85%
Indirect Impact
150
110
25%
Overall Impact
350
140
60%
4. This forecast reduction in the global warming impact of refrigeration can be
achieved with widespread usage of HFC refrigerants.
5. The majority of other emitters of global warming gases are unable to make such a
positive contribution. For example, the transport sector had EU global warming
emissions of 220 GWP Mtonnes in 1990. However, it is estimated there will be an
increase of 10% by 2010. This increase is because the growing number of vehicles
and journeys outweighs improved energy efficiency.
6. There are three main refrigerant options currently available i.e. ammonia,
hydrocarbons and HFCs. It is shown that each of these refrigerant options has a
role to play in the future of refrigeration.
7. The various ways in which global warming emission reduction will be achieved
are discussed. These include leakage and refrigerant charge reduction, improved
energy efficiency and use of ammonia and hydrocarbons where appropriate.
8. HFC refrigerants are shown to be of vital importance for many refrigeration
applications when safety considerations are taken into account.
9. When systems are properly designed to ensure low levels of refrigerant leakage
and to maximise energy efficiency there is little or no difference between the
global warming impact of ammonia, hydrocarbon or HFC systems. All can achieve
considerable reductions in GW emissions when compared to the 1990 baseline.
10. Comparisons made in this report are based on the ‘real’ situation in 1990, when
significant CFC and HCFC emissions were being made. Many publications ignore
emissions of ozone depleting substances and hence give a false picture when
comparing future emissions to the 1990 baseline.
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1.
INTRODUCTION
Users of refrigeration are facing new choices with regard to selection of refrigerants
because CFC and HCFC refrigerants are being phased out to protect the ozone layer.
There is considerable confusion and controversy regarding the best choices,
particularly when the environmental issue of global warming is taken into account.
This report is intended to provide a balanced review of competing options in order to
help users, designers and policy makers fully understand their relative benefits.
A key theme within this report is to examine the role of HFC refrigerants as
alternatives. There is mounting pressure against these fluids from some environmental
groups because it is claimed that refrigeration systems using HFCs have an excessive
global warming impact. Is this pressure fair and how do HFCs compare to other
options (and the CFC systems they are replacing)? Key factors that influence the
global warming impact of refrigeration are discussed in order to identify the
appropriate refrigerant for use in different applications.
The choice between competing refrigerants has always been complex. Nevertheless,
there used to be fairly clear divisions between different types of refrigerant. CFCs and
HCFCs were the refrigerant of choice for the vast majority of small and medium sized
refrigeration systems (and many large ones). This was because of their excellent safety
characteristics (non-toxic and non-flammable) and good materials compatibility
(allowing use of copper components). Ammonia, a traditional refrigerant used for over
100 years, maintained a significant niche market in large industrial systems,
particularly in the food and drink manufacturing industry and cold storage.
Hydrocarbons were also used, but their market was restricted, mainly to large systems
in certain petrochemical companies who were handling these highly flammable fluids
within their manufacturing process.
What are the options for the future? Well over 95% of refrigeration applications use
vapour compression refrigeration. Whilst other options such as absorption
refrigeration and air cycle systems have a small market potential it is unlikely that
there will be a significant move away from vapour compression cycles during the next
20 years. Hence, this document restricts itself to the options for vapour compression
systems.
Currently, there are four main options that an end user can consider: HFCs,
hydrocarbons (HCs), ammonia and elimination of the need for refrigeration. There are
advantages and disadvantages for each. Some of the key issues include safety, cost
(first cost and operating cost) and global warming impact. This report reviews
refrigerant options and provides a logical and balanced framework to help users select
the best one for them. Our general belief is that all four options are applicable in
certain circumstances. The key issue is to identify what these circumstances are.
The report has been written to be of broad interest, both to those with relatively little
refrigeration knowledge and to those with an in depth understanding of design issues.
Hence, some background material is included early in the report followed by more
detailed analysis. The document is split into three main parts. Part A, provides
background to refrigeration and refrigerants. Part B gives background to global
warming. Finally Part C analyses the global warming impact of refrigeration.
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2.
REFRIGERATION APPLICATIONS
To properly understand the difficulties facing refrigeration systems designers it is
important to be aware of the enormous range of applications. Refrigeration represents
one of the most important energy-using utilities in all sectors of human activity:
domestic, commercial and industrial. People often find it surprising that refrigeration
and air-conditioning systems represent approximately 15% of EU electricity demand
(Source - EEBPP 1). This makes it one of the largest definable electricity using groups
(larger than, for example, lighting).
Refrigeration applications range enormously in size and temperature level. A domestic
refrigerator has a cooling load of a few hundred watts whereas large industrial systems
can have loads in excess of 10 MW. Small systems contain less than 100g of
refrigerant whereas large ones can contain many tonnes. Temperatures range from
specialist cryogenic applications (below -150oC), through a wide variety of industrial
and food chain requirements between -40oC and 10oC, to air-conditioning and heat
pump applications at temperatures of 20oC and above. Some refrigeration systems can
be operated in restricted locations where only trained personnel are present. Other
systems, such as those for supermarkets and building air-conditioning, operate where
there are numerous untrained members of the public. All these variations lead to
widely differing refrigeration system designs. Because of the wide variety of
circumstances in which refrigeration is used, there is no single refrigerant that suits all
applications; there is a need for various refrigerants with different properties.
The main requirements for refrigeration systems fall into four distinct groups:

The food and drink chain, including agricultural, manufacturing, storage, transport,
retailing and domestic requirements.

Other industrial processes, including applications in sectors such as chemicals,
pharmaceuticals and electronics.

Comfort conditioning, including domestic, commercial and industrial buildings

Mobile air-conditioning in cars and other vehicles.
In this short report we cannot give an adequate description of the full variety of
applications and designs. However, it is worth noting that most very small systems
(such as domestic refrigerators and small commercial units like icemakers, small retail
displays etc) are based on hermetic designs. These are factory built units using only
welded or brazed joints. They contain very small refrigerant charges and suffer very
little from leakage. Larger systems usually require some or all of construction to be
carried out on site and there are numerous pipe joints and seals required. Refrigerant
charge is much higher and the chance of refrigerant leakage is significant.
It is also useful to distinguish between ‘Distributed Systems’ that circulate the
refrigerant itself to cool a building or a process and ‘Secondary Refrigerant Systems’
that incorporate a secondary fluid to transmit cooling to the user (often water or an
‘anti-freeze’ solution). Secondary refrigerant systems have the advantages that they
can reduce the quantity of primary refrigerant required and allow it to be contained
within a limited physical area such as a plant room. This considerably limits the
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potential for leakage and eases safety problems if flammable or toxic refrigerants are
used. However, there will usually be an energy penalty, because of the need to pump
the secondary refrigerant and to account for the extra temperature difference between
the primary and secondary circuits.
One can attempt to quantify the size of the refrigeration market in a number of
different ways including number of systems, quantity of refrigerant used and energy
consumption. The following estimates are based on References EC DGIII, UK DoE 1,
UK DoE 2 and March Consulting Group estimates.
In terms of number of systems the domestic sector is totally dominant, with some 200
million systems in use in the EU. This compares with about 30 million small systems
for retailing and air-conditioning and about 2 million larger systems for supermarkets,
large buildings and industrial applications. However, if we analyse the quantity of
refrigerant contained within all these systems or the annual energy consumption a
quite different picture will be obtained. In terms of refrigerant quantities the
supermarket, industrial and air-conditioning sectors become the most important, with
domestic systems being the 4th largest segment. Figure 1 gives an approximate
breakdown of the EU refrigerant bank in terms of end use sectors.
The various fluorocarbons including CFCs, HCFCs (and more recently HFCs)
represent in the region of 80 to 85% of the total EU refrigerant bank. Ammonia
represents a further 10 to 15%. Hydrocarbons have historically represented a very
small proportion of the total bank, probably in the region of 1 to 2%. Recent growth in
the market for hydrocarbons in the domestic and small refrigeration field will have
caused this to grow but the total is currently less than 3% of the EU bank.
Figure 1 Approximate Split of the EU Refrigerant Bank, 1990
Transport
4%
Small Commercial
10%
Supermarkets
27%
Domestic
12%
Air-conditioning
22%
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3.
SELECTING REFRIGERANTS
As already discussed the process of refrigerant selection is quite complex. This is
because there are a significant number of parameters that need to be assessed and few
available fluids ‘score well’ on all of them. The key parameters include the following:
Thermodynamic performance - for the required evaporating and condensing
temperature levels the fluid should be able to provide energy efficient performance
(i.e. a high coefficient of performance or COP).
Appropriate operating pressures - the evaporating pressure should not be too low
and the condensing pressure should not be too high (under the relevant operating
temperatures). Ideally the evaporating pressure should be higher than atmospheric
pressure and condenser pressure should be below around 20 bar(g).
Compressor size - the thermophysical properties for the fluid should result in as small
a compressor as possible
Toxicity - the fluid should be of zero or low toxicity
Flammability - the fluid should be non-flammable and non-explosive.
Materials compatibility - the fluid should be compatible with various materials used
in the construction of a refrigeration plant (e.g. pipes, vessels, gaskets, seals etc).
Oil compatibility - the fluid should perform well with available lubricating oils.
Stability - the fluid should remain stable throughout many years of operation and must
not chemically react with system components, lubricating oil and contaminants.
Cost - the fluid should have reasonable cost.
Ozone Depletion Potential - the fluid should have a zero ODP.
Global Warming Potential - the fluid should have a zero or low GWP.
Prior to the Montreal Protocol, CFCs and HCFCs were the obvious choice for many
applications. Whilst they were not the cheapest refrigerants to buy (e.g. ammonia was
less than 25% of the price of CFCs) they led to plants with minimum ‘total ownership
cost’. They had good materials compatibility and it was easy to deal with safety issues.
CFCs can no longer be selected because of their high ODP. In the future we should
only consider zero ODP fluids and we also need to ensure minimum global warming
impact. In simplistic terms this may seem to suggest fluids with zero or low GWP are
best. However, as we shall see later in this report, the use of a fluid with a higher
intrinsic GWP does not necessarily lead to the highest overall global warming impact.
Bearing in mind the list of issues described on the previous page it is useful to
examine the advantages and disadvantages of the four main refrigerant options listed
in the introduction.
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Ammonia
Ammonia is a refrigerant that has been used since the very earliest days of vapour
compression refrigeration. It has good thermodynamic properties for systems
operating with evaporating temperatures above about -50oC and with condensing
temperatures below about +40oC. Ammonia is not an appropriate refrigerant for very
low temperature applications (below –50oC). Ammonia has good compatibility with
mineral lubricating oils and excellent stability over long system lifetimes. It is one of
the cheapest available refrigerants in terms of cost per kilogram. The environmental
properties are excellent, as the fluid has zero ODP and zero GWP.
The main drawbacks of ammonia are toxicity, flammability and materials
compatibility. The fluid is highly toxic and causes severe risk to humans when
significant leakage occurs. The dangers are particularly significant if untrained
personnel are involved, as the noxious fumes can create panic. Ammonia is flammable
in certain concentrations, although it is actually relatively hard for a fire or explosion
to occur. On the more practical side ammonia is incompatible with copper which
restricts the materials that can be used for plant construction. All copper and brass
components must be avoided and ammonia systems are constructed mainly with steel
components. For small plants this can add significantly to the cost.
HFCs
HFCs also have good thermodynamic properties and the added advantage over
ammonia that they are a family of fluids with different operating pressures. Hence,
HFCs can be used across a wider range of application temperatures and can be more
carefully selected to optimise system efficiency. Most HFCs have very low toxicity
and zero flammability and they have excellent materials compatibility. Hence they do
not suffer some of the drawbacks of ammonia.
On the negative side HFCs have a significant GWP; if they are to be responsibly used
it is essential that emissions should be minimal. They are relatively expensive fluids
although this usually is only an issue in large refrigeration systems. They are not
compatible with conventional mineral lubricating oils and it has been necessary for
new synthetic oils to be developed for HFC refrigeration systems. This development
has been successfully completed.
Hydrocarbons
As with ammonia and HFCs, hydrocarbons have good thermodynamic properties and
as they form a family of fluids, there can be good selection over a relatively wide
range of application temperatures. Hydrocarbon refrigerants have low toxicity and
good materials compatibility. They also have good environmental properties with zero
ODP and very low GWP.
The key drawback to HCs is their very high flammability. Any significant leakage
could lead to a fire or an explosion. For this reason, hydrocarbons have historically
been restricted to use in petrochemical facilities that are handling these flammable
fluids as part of the main manufacturing process. More widespread application
requires very careful attention to flammability safety issues.
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Elimination of refrigeration
This fourth option is always worth considering when developing plans for a new
refrigeration plant. If refrigeration can be eliminated there are obvious and significant
environmental benefits. No refrigerant fluid is used so the GWP is irrelevant. More
importantly, no energy is used hence there may be a significant reduction in the
overall global warming impact. There are numerous examples of elimination of
refrigeration, ranging from use of ambient free cooling, to reductions in load from
better process integration to completely new approaches to processing (e.g. use of
irradiated food instead of refrigerated food).
The clear disadvantage of this option is the relatively narrow applicability. For the vast
majority of current refrigeration applications, whilst there may be some good
opportunities for cooling load reduction, complete elimination of mechanical
refrigeration is often impossible.
This option is not often given the attention it deserves. In many cases the elimination
(or reduction) of a refrigeration load not only saves energy, but also saves capital cost!
Options for Different Sized Refrigeration Systems
Relating the general characteristics of refrigerants, as described above, to the main
refrigeration applications it is possible to draw up general rules for the usability of
refrigerants. Table 1 outlines the results of such a comparison. It should be noted that
the four categories of refrigeration chosen simplify what is a much more complex
picture. The dividing lines between these categories may not always be obvious. It
should also be noted that if capital cost is irrelevant, the safety issues that make
ammonia and hydrocarbons difficult to use could be overcome. Bearing these points in
mind, Table 1 provides a useful ‘feel’ for the cost-effective use of refrigerants.
Table 1 General Applicability of Refrigerants (for cost-effective and safe usage)
Refrigeration Application Category
1. Very Small Systems
e.g. domestic refrigerators, icemakers, through the wall a/c.
Hermetic systems, very low refrigerant charge.
2. Distributed Systems used in public areas
e.g. supermarkets, split system a/c, small cold stores.
Refrigerant charge larger and leaks affect untrained people.
3. Distributed Systems used in restricted areas
e.g. food factories, cold stores.
Usually large industrial systems.
4. Secondary Refrigerant Systems
e.g. water chillers, glycol chillers.
Refrigerant in restricted plant room with no public access.
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Ammonia
HCs
HFCs
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4.
THE IMPACT OF REFRIGERATION ON GLOBAL WARMING
Many volumes have been written on the mechanics of global warming. Simply stated:
radiation from the sun hits the Earth and some is re-emitted into the atmosphere as
infrared radiation. When the infrared light tries to leave the atmosphere, some of it
gets reflected back to the Earth by the greenhouse gases. This trapped energy then
warms the planet.
There are many greenhouse gases, some of which are naturally occurring such as
water, carbon dioxide and methane. The natural global warming process ensures the
earth keeps itself warm enough for human habitation. The problem is that humans are
adding more and more carbon dioxide into the atmosphere by burning fossil fuels for
power, transportation and industry. We have also added other man-made greenhouse
gases, such as nitrous oxides (NOx) and fluorocarbons (FCs).
There is a growing acceptance in the international community that action is required to
reverse the growth in the emission of greenhouse gases. However, it is also recognised
that this must be achieved without causing intolerable human hardship and the
triggering of a world-wide recession through draconian legislation. It is thus important
to target the areas where the largest reductions can be achieved with least impact to
human activity.
Contributors to Global Warming
Figure 2 Global Warming Emissions,
1990
In 1990 there were four main manmade greenhouse gases: CO2,
Methane, NOx and FCs. CO2 was by
far the largest single contributor.
Before 1990, when the environmental
effects of FC emissions were not fully
understood, FCs were responsible for
the second largest contribution to the
total. Figure 2 shows the relative
impact of the four gases. The data
includes emissions of CFCs and
HCFCs. (Source AFEAS).
Methane
15%
FCs
24%
NOx
6%
CO2
55%
The Role of Fluorocarbons in Global Warming
Clearly, from the 1990 emissions figures much attention was required to target the
emissions of fluorocarbons. They were used for a variety of processes due to their
excellent physical properties and safety record. Major uses included: aerosols, foams,
solvents and refrigerants. Refrigerants accounted for only 15% of the 1990 emissions
of fluorocarbons (hence 4% of all GW emissions). Since this date much effort has
been made by the industry both through self-regulation and Government intervention
to reduce this figure. The progress made within the European Union over the last five
years has been enormous as is shown in Figure 3. (Source ICI)
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Figure 3 Emissions of fluorocarbons used within the EU
1500
Mtonne s CO
2
e quivale nt
1000
CFCs
HCFCs
500
HFCs
0
1989
1990
1991
1992
1993
1994
1995
Enormous progress has thus been made in reducing the usage of fluorocarbons (with
an 82% fall in GWPtonnes between 1990 and 1995). Most of this improvement is
from the aerosol, solvent and foam sectors, although there has also been a useful
contribution from refrigeration. By the year 2010, EU emissions of both CFCs and
HCFCs are likely to be almost eliminated. The use of HFCs should be confined to the
sectors where performance, safety and cost factors dictate that they are still the best
option. This may include refrigeration, medical aerosols and foam production. The
chemical and user industries must remain vigilant that less crucial applications (such
as the proposed self-cooling drink can) are not allowed to develop.
The Indirect Impact of Refrigeration on Global Warming
As we have seen, carbon dioxide is the main greenhouse gas. This gas is the product of
combustion for all fossil fuels currently used for energy generation. Any assessment of
the impact of refrigeration on global warming must consider not only the direct effect
of refrigerant emissions, but also the indirect effect of the carbon dioxide emissions
resulting from the energy required to operate the refrigeration system. The sum of the
direct and indirect emissions is known as the Total Equivalent Warming Impact
(TEWI). Indirect emissions from refrigeration systems are estimated to represent 3%
of 1990 GW emissions (Source EEBPP 1 and March Consulting Group estimates). It
is important to understand the relative magnitude of the direct versus the indirect
impact. Figure 4 shows the relative 1990 contributions from three distinct types of
refrigeration appliance. (Source Greenpeace 1)
Figure 4 TEWI Comparison for 3 Refrigeration Applications, 1990
Domestic Refrigerator
96%
Commercial Air Conditioning Car Air Conditioning
44%
4%
70%
Direct
Direct
Direct
Indirect
Indirect
Indirect
56%
30%
It can clearly be seen that, for 1990 domestic refrigerator designs, maximum benefit
can be gained by targeting energy efficiency improvements. For car air-conditioning,
great strides are needed in reducing the direct impact of the refrigerant leakage.
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5.
INTERNATIONAL EFFORTS TO REDUCE GLOBAL WARMING
IMPACT
Legislative/Governmental Initiatives
To fully appreciate the options that Governments can adopt to limit the impact of
global warming it is helpful to compare the processes that are currently being followed
with regard to both ozone depletion and global warming.
Ozone depletion issues are being addressed through the Montreal Protocol. The MP
process is based on fluid production bans. In developed countries many ozone
depleting substances are already subject to a production ban. Usage of existing
material is allowed and the MP does not curb emissions of existing ozone depleting
substances. The rationale behind this legislative process is that emissions will fall
towards zero as the production ban begins to have an impact. The largest users of
ozone depleting substances were highly emissive (e.g. aerosol, flexible foam and
solvent applications) and the production ban process has quickly driven such users to
switch to alternative materials.
Global warming issues are being addressed through the Framework Convention on
Climate Change. The FCCC is quite different in nature to the MP. The process relies
on control of emission of global warming substances. The reason for this different
approach is obvious: the main global warming gas is carbon dioxide and it would be
impractical to consider a ban on the man-made production/emission of this gas.
In the case of HFCs there is a danger of these two mechanisms becoming confused.
The current users of HFCs (and many HFC policy makers) were previously affected
by the Montreal Protocol. Because of familiarity with the MP mechanism there is a
natural reaction to mistakenly consider a ban on HFC production. This is quite
illogical; it is the emission of HFCs that should be considered not the production.
It should also be noted that the FCCC is comparing global warming emissions in 1990
with those in the future. However, the FCCC ignores 1990 emissions of substances
being banned under the MP. In 1990 the refrigeration sector had significant global
warming impact through leakage of CFC and HCFC refrigerants. Taking these into
account, it can be shown that the sector can make large reductions in global warming
impact, providing the care being taken to limit emissions of HFCs is continued.
Voluntary Initiatives
The refrigeration user industry and chemical producers are conscious of the fact that
the historical use of CFCs and HCFCs was profligate, both for refrigeration and other
applications. Before the adverse environmental effects were identified, wastage and
leakage were the norm and use for highly emissive applications such as general
aerosols was accepted. These groups agree that this attitude cannot be allowed to
continue for HFCs. Because HFCs have a high GWP it is essential that they be used
responsibly and that all efforts are made to minimise emissions. Highly emissive
applications should not be allowed unless the benefits to society outweigh the
contribution to GW; emissive use of HFCs for medical aerosols is a good example.
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6.
OPPORTUNITIES TO REDUCE THE GLOBAL WARMING
IMPACT OF REFRIGERATION
In 1990, refrigeration and air-conditioning systems represented approximately 7% of
all greenhouse gas emissions from the EU: 4% through emissions of CFCs and HCFCs
and 3% through indirect emission of CO2. This contribution is significant and stresses
how important it is for refrigeration users to reduce their 1990 global warming impact.
These figures emphasise that it is the TEWI of a refrigeration system that must be
reduced. Addressing the issues of energy efficiency, refrigerant charge and refrigerant
leakage rates will have far more impact than simply considering the GWP of the
refrigerant chosen. In the remaining sections we shall consider in detail the potential
for minimising the impact of emissions from the refrigeration sector.
Mechanisms for Reducing Global Warming Impact
There are a number of ways in which the GW impact of refrigeration systems can be
reduced. These give the opportunity for refrigeration users to make the largest single
improvement to GW emissions of any end use sector. Rather than wasting effort
attacking the use of HFC refrigerants, one should encourage the refrigeration industry
to make the far greater gains possible by applying a more ‘holistic’ approach. Tackling
the following areas will lead to major improvements:
 Reduction in Leakage. Historical FC leakage levels are unacceptably high in
many application areas. There is potential to reduce current average leakage
rates by at least 30% - 40%. The potential is particularly good for distributed
systems.
 Reduction in System Charge. Using systems with much lower refrigerant
charge can lead to further emission reductions. By using secondary refrigerant
systems in appropriate applications charge can be reduced by up to 90%.
 Energy Efficiency Improvements. Levels of efficiency in 1990 were
relatively low. Savings of at least 25% can be cost effectively achieved.
 Reduction in Fluorocarbon GWP. The average GWP of HFCs being used
to replace CFCs is much lower (e.g HFC 134a has a GWP of 1300 compared
to the fluid it replaces, CFC 12 with a GWP of 8100)
 Reduction in Use of FCs. As described in Section 3, there are options to use
ammonia, HCs and to eliminate refrigeration altogether. These should be
adopted wherever it is appropriate.
Weighed against these areas for improvement, it should not be forgotten that there is
potential for some growth in the market size for certain applications of refrigeration,
particularly car and domestic/commercial air conditioning. The following sections will
review in turn, the opportunities for emissions reduction in each of the refrigeration
sectors. Balanced against this, the safety implications of switching to flammable
refrigerants and the relative lack of experience of the use of these refrigerants will also
be discussed.
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7.
DIRECT EMISSION REDUCTION OPPORTUNITIES
The impact that any refrigerant will have on global warming is solely dependent on
whether it is released to the atmosphere. If a “perfect” system could be produced in
which leakage to the atmosphere never occurred and if the refrigerant was totally
recycled at the end of it’s working life then the GW impact would be zero irrespective
of the refrigerant GWP. Whilst such perfection is impossible, direct emission rates can
be reduced substantially from current levels. Emissions should be minimised for all
refrigerant options; if HFCs are used this is to prevent GW, whereas if ammonia or
HCs are used low emissions are crucial for safe operation.
There are three basic opportunities for reducing direct GW emissions:
 Reduction of annual leakage rate.
 Reduction of refrigerant charge.
 Improved rate of recovery on system disposal.
The rate of leakage is highly dependent on the type of application and design
considered. Domestic refrigerators and other small hermetic systems are factory built
using only welded or brazed joints and hence leakage is minimal. They also contain
very small refrigerant charges. Historical leakage rates are only about 1% of the
refrigerant charge per year. There is little potential to improve this leakage rate or to
reduce the refrigerant charge. For small hermetic systems there is an opportunity to
improve the rate of recovery at the end of system life or to use hydrocarbon
refrigerants in place of HFCs. However, energy usage represents about 98% of the
TEWI of an HFC 134a refrigerator and it is this impact that requires most attention.
Larger systems fall into two main categories involving either distributed use of
refrigerant or more confined use of refrigerant in a "central plant". The potential for
leakage in distributed systems is particularly significant as they usually involve
numerous pipe joints and valves which have to be fitted on site. Distributed systems
usually contain a relatively high specific refrigerant charge (i.e. the ratio of quantity of
refrigerant (kg) to cooling duty (kW)). There are numerous examples of distributed
system ranging from small split system air-conditioning units, through supermarket
systems to large industrial plants used in food manufacture and cold storage. Historical
leakage rates from distributed systems using fluorocarbons are high. A typical 1990
supermarket system loses 30% of the refrigerant charge per year and the specific
refrigerant charge is high because of the length of distribution pipework required. It is
interesting to note that leakage rates from distributed ammonia systems tend to be
lower because steel pipework is used (which is less prone to certain types of leakage
problem than copper pipework) and continual effort is made to limit leakage of this
highly toxic refrigerant.
Central plants fall between the leakage rates of small hermetic systems and the
distributed systems described above. These plants are substantially factory built, with
higher levels of manufacturing quality control available than for site erected systems.
Specific refrigerant charge has the potential to be lower than equivalent distributed
systems, although many older designs (using flooded shell and tube evaporators)
actually have a quite high specific refrigerant charge. Modern evaporator designs,
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especially plate heat exchangers, can lead to significant reductions in the specific
refrigerant charge of a central plant. Historical leakage rates from central plants have
typically been in the region of 10% per year. Significant potential exists for reduction
in leakage rates from both distributed and central systems.
Transport refrigeration systems and mobile air-conditioning face extra problems from
the leakage perspective because of significant levels of vibration and the effect of
impact with small objects like grit and stones. In countries where salt is applied to
roads to prevent freezing there is the added potential problem of corrosion.
Historically mobile air-conditioners, particularly those built and used in the USA have
had a very poor leakage record with annual leakage of 50% to 100% of refrigerant
charge. Private discussions with a major European car manufacturer indicate that there
is enormous potential for improving this historical position. They indicate that a well
designed system can achieve leakage rates of about 2% per year.
With the exception of small hermetic systems it is clear from the description above
that there is significant potential to reduce annual leakage rates and specific refrigerant
charge in many areas of refrigeration application. This potential can be achieved at
relatively low cost by applying a number of "common sense" design and maintenance
principles to the industry. A few examples of key areas for attention include:
 reducing large leaks from distributed systems that currently use over-stressed
copper pipework
 reducing the gradual leakage that occurs from systems that use flared
compression joints to connect pipework
 improving the design of valves to reduce leakage through valve stem seals
 improving the design of compressors to avoid shaft seal leakage
 improving management techniques to detect leaks early and to ensure that they
are quickly repaired.
Whilst the technical potential for leakage reduction is excellent there needs to be some
process put in place to ensure that this potential is achieved. This could either be
through voluntary agreement or legislation. Although leakage from refrigeration
systems has improved during the last five years, it appears that current legislation is
not strong enough to encourage more effective and widespread improvement.
It is interesting to note that a number of refrigerant leakage Codes of Practice have
been recently published by organisations in the refrigeration industry (e.g. the UK
Institute of Refrigeration published such a code in 1996, source: IOR). A voluntary
agreement between the UK refrigeration industry and UK Government concerning use
of HFCs in refrigeration quotes this Code of Practice as the basis for leakage
standards. The ‘Responsible Refrigeration’ concept being promoted by chemical
companies and the refrigeration industry encourages this type of action. Nevertheless,
there is still a lot of room for improvement. Bearing in mind the excellent potential it
may be appropriate for HFC emission standards to be legislated as is the case in the
Netherlands.
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8.
ENERGY EFFICIENCY OPPORTUNITIES
As discussed in previous sections of this report the energy efficiency of refrigeration
systems represents a key opportunity for reducing global warming impact. Data for
1990 showed that energy usage represented approximately 45% of the total TEWI for
refrigeration. If the opportunities to reduce direct emissions, described in Section 7,
are adopted then the need for energy efficiency becomes even more significant.
There is really excellent scope for the improvement of the efficiency of refrigeration
systems. In many existing systems 20% can be saved at relatively low cost. The
overall technical potential may be as high as 40%. This scope has been well
understood for many years. Whilst there are some signs of efficiency improvements
over the last five years, there is still a massive untapped potential. (Sources: there are a
number of useful publications discussing refrigeration efficiency issues. The following
paragraphs make use of examples and data from various UK documents including
EEBPP 2, 3, 4, 5, 6 and UK DoE 3).
When comparing the relative benefits of using HFCs, ammonia or HCs is it important
to establish how much the selection of the refrigerant can affect the energy efficiency?
There is a lot of evidence to show that differences between the main refrigerant
options only have a secondary influence on energy efficiency. Refrigerants do exhibit
varying thermodynamic performance and hence energy efficiency, but there are a
number of other issues that are of far more importance to refrigeration plant efficiency.
Ironically, in many of the publications extolling the virtues of alternative refrigerants
little attention has been given to general opportunities for improving energy efficiency.
Refrigeration Efficiency Opportunities
The opportunities for improving the efficiency of refrigeration systems can be subdivided into the following five groups:
1. Reduction of cooling demand. When considering any new refrigeration
application the essential first step is to review the cooling demand and make every
effort to reduce the size of the cooling load. There are numerous ways to do this. In
a domestic refrigerator, insulation thickness can be increased. In a building airconditioning system efforts can be made to shade the building from solar gain or to
use free cooling at those times of the year when ambient temperatures are low
enough. In many refrigeration applications auxiliary loads such as evaporator fans,
refrigerant pumps and cold store lighting can be better designed and controlled to
reduce power input. It is surprising how many refrigeration systems are built
without a proper review of these cooling load reduction opportunities. The overall
technical potential for reducing cooling demands is probably in excess of 25%.
2. Improved system design. Once the cooling load has been minimised there are
usually numerous system options available to the plant designer. Historically,
many high efficiency design options have been ignored or overlooked. A
particularly common mistake is to design a plant to be efficient at the ‘design
point’ (maximum cooling load under summer time operating conditions). Most
systems actually spend much of the time running with lower cooling loads and
cooler ambient conditions, but rarely does the design enable performance to be
optimised at all these different conditions. Another common design fault is to
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oversize the system, leading to poor part load efficiency. Many existing plants
employ very poor control systems and these can have a great influence on
efficiency. There are numerous other system design opportunities such as use of
sophisticated cycles (e.g. two stage systems) and use of techniques such as thermal
storage. The overall technical potential for improved system design is probably in
excess of 20%.
3. Improved component design and selection. The individual components in a
refrigeration system require careful selection if efficiency is to be optimised. The
most important opportunity is compressor efficiency. Many existing plants utilise
compressors of relatively poor efficiency. Improvements of 10% can often be
made at no extra cost. Use of extra evaporator or condenser surface area can often
be a worthwhile investment. Other detailed issues such as pipe line and valve
pressure drop, defrost system design, oil separation effectiveness etc. all have an
influence on efficiency. The overall technical potential for improved component
design and selection is probably in excess of 15%.
4. Improved operation and maintenance practices. Even if a plant is designed to
have very high efficiency there is no guarantee that this level of performance will
be achieved during the operating life of the equipment. Because refrigeration
systems are relatively complex many end users find it difficult to ensure that
efficient operation is maintained. When existing refrigeration systems are carefully
analysed by experts it is the norm to find significant opportunities for efficiency
improvements. These can usually be achieved by small changes in operating
practice (such as better compressor sequencing or temperature control) or
improved maintenance (such as ensuring no build up of non-condensable gases in
the condenser or reducing excessive frost on evaporators). Very few refrigeration
systems have sufficient metering to allow proper energy efficiency analysis to be
carried out on a regular basis. For example, compressors are rarely fitted with kWh
meters. The overall technical potential for improved operation and maintenance
practices is probably in excess of 20%.
5. Optimum selection of refrigerant. As discussed in the introduction to this section
there are differences between the thermodynamic performance of different
refrigerant fluids. Whilst these could in theory lead to significant differences in
efficiency, it should be noted that few fluids would reach the market if their
performance was significantly worse than competing options. For a wide range of
refrigeration applications one would not expect more than about a 5% difference in
efficiency between ammonia or the most appropriate HFC or hydrocarbon.
It is clear from the description given above that there are really excellent opportunities
for refrigeration users to make energy efficiency improvements. What is of crucial
importance to the refrigerant selection process is to note that refrigerant properties are
one of five areas for potential improvement of energy efficiency and that they
represent the smallest of these opportunities. Hence, when assessments are made of the
potential to reduce indirect GW impact, the selection of the refrigerant itself has little
overall influence.
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9.
SAFETY ISSUES
When selecting a refrigerant, safety issues cannot be overlooked. The major
drawbacks of HFC alternatives are the safety characteristics. Ammonia is highly toxic
and slightly flammable; HCs are highly flammable. The small potential for TEWI
improvement through use of zero/low GWP refrigerants must be offset against
additional safety risks. It is striking that little research has been published regarding
the relative risks of HFCs, HCs and ammonia.
Table 2 illustrates some of the characteristics of different refrigerants from a safety
perspective. The toxicity rating is given in terms of the Occupational Exposure Limit
(OEL). The 1000 ppm limit on non-toxic substances is to prevent any danger of
suffocation due to oxygen displacement. Flammability properties are characterised by
the concentration limits in which combustion can take place and by the auto-ignition
temperature. The very low concentration that is required to sustain combustion with
iso-butane is an indication of the high level of flammability of hydrocarbons. Most
HFC refrigerants are non-flammable, as illustrated by HFC 134a. However, HFC 32
has been included to illustrate that some are flammable. In most situations HFC 32 is
used in a mixture with other HFCs. The mixtures are carefully formulated to ensure
zero flammability throughout their full operating range and in leakage situations.
Table 2 Toxicity and Flammability Characteristics of Certain Refrigerants
Refrigerant
Toxicity Rating
Flammability Ratings
OEL, ppm
Flammability limits
Auto-ignition
Temperature oC
15 to 28%
630
1.8 to 8.5%
460
Non-flammable
12.7 to 33.4%
648
% concentration in air
Ammonia
Iso-Butane
HFC 134a
HFC 32
25
1000
1000
1000
The risk of a fatality from ammonia refrigeration systems is estimated to be at least 1.5
per million installations per year (Source - IEA). If the 30 million commercial and
industrial refrigeration systems estimated to be in the EU were all operated on
ammonia this could result in an additional 50 fatalities each year. This assumes that
accident rates remain the same as those in historical data. If there is much more
widespread use of ammonia it is likely that the accident rate would rise because of the
lack of experience of ammonia use in both the refrigeration contracting and end user
sectors.
There is little published data on the risk factors related to HC refrigerants as they are
not currently in widespread use. It is reasonable to assume that the safety record for
HCs used in domestic refrigeration and small hermetic units should be good as long as
stringent quality control is maintained, since the actual refrigerant charge is very low.
However, even a risk factor 100 times better than that for ammonia systems could still
result in a number of fatalities in the EU due to the high number of units in use. For
larger systems, with higher refrigerant charge and greater risk of leakage, risks are
likely to be even higher than for ammonia because of the high flammability.
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There is also little published data for risks related to HFCs, but some is available on
use of CFCs and HCFCs. These have led to some fatalities over the years, mainly due
to suffocation. This is a risk with any inert gas; e.g. engineers have died in confined
areas that are full of refrigerant vapour. The number of fatalities reported is far lower
than for ammonia systems, even though there are significantly more FC systems in
use. The risk of fatalities with FCs is several orders of magnitude lower than for
ammonia (source IEA).
Track Record and Experience with Installations
There is inadequate contractor and end user experience to cope with a rapid mass
switch away from FCs to ammonia or HCs. For example, in the UK there is a
Refrigerant Handlers Register that proves the competence of technicians operated by
the Air-conditioning and Refrigeration Industry Board. They currently have 2350
technicians registered to handle HFCs and only 100 registered for ammonia (4% of the
total). A rapid switch to ammonia or HCs would entail a massive requirement for retraining. Calor Gas, a supplier of HCs has trained over 3000 engineers in the UK.
However, there are few non-domestic HC installations, so the majority of these will
have had no further experience with HCs. There is even less ammonia or HC
experience amongst engineers in end-user companies – particularly in non-industrial
organisations. The use of inexperienced operators on toxic/flammable systems could
considerably raise the accident rate.
Suitability of refrigerants to different systems
Given the safety issues raised above, a responsible approach to the substitution of FCs
with flammable or toxic refrigerants is clearly required. Table 1 on page 7 summarises
a logical framework for cost effective and safe refrigerant application.
For Very Small Systems ammonia cannot easily be used because of materials
compatibility problems. Selection of HCs is a reasonable option; safety risks should be
small as only a small refrigerant charge is used and leakage is minimal. However,
caution should be exercised as little track record of performance yet exists and
maintenance contractors have limited hands-on experience.
For Distributed Systems used in public areas great care is required since leakage
rates are high and untrained people are in an area of potential leakage. Ammonia and
HCs are not appropriate (and sometimes not allowed by safety codes, source BS 1). If
HFCs are used it is essential that sufficient investment is made in leakage prevention.
For Distributed Systems used in restricted areas there is more flexibility as staff can
be trained what to do if a major leak occurs. Ammonia or HFCs can be considered for
this type of system. The high flammability of HCs makes them inappropriate in
‘normal’ working areas such as food production halls. They may be applicable in
special situations, such as outdoor distributed systems in petrochemical works.
For Secondary Refrigerant Systems it is reasonable to consider any of the three main
options as safety issues are easier to deal with in a single plant room with restricted
access. However, before there could be widespread use of ammonia or HCs in new
secondary refrigerant application areas such as supermarkets it is essential that the
contractor experience issues discussed above be addressed.
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10.
END USE SECTOR REVIEW
Each sector of the refrigeration market has unique characteristics that define the
potential for reducing the global warming impact. To simplify analysis it is useful to
consider six distinct sectors of the refrigeration market, namely: domestic; small
commercial (e.g. shops, pubs, hotels) large commercial (supermarkets); industrial;
building air-conditioning; mobile air-conditioning. In each sector it is possible to
estimate the GW impact of a number of scenarios that incorporate the opportunities
introduced in Section 6. The scenarios used in this report are as follows:

Scenario 1. Baseline estimate of 1990 GW emissions (defined as 100)

Scenario 2. Easy reductions in leakage (direct emissions)

Scenario 3. Scenario 2 + easy reductions in energy efficiency (indirect emissions)

Scenario 4. Scenario 3 + further investment in both leakage prevention and energy
efficiency

Scenario 5. Scenario 4 + widespread substitution of FCs with ammonia or HCs.
It is important to note that Scenarios 2 and 3 can be applied to existing systems,
through ‘retrofit’ investments whereas Scenarios 4 and 5 are only cost effective when
applied to new (or replacement) systems.
Sector 1 Domestic Refrigeration
Domestic refrigeration systems are hermetically sealed units, thus leakage rates are
low. In 1990 only 4% of the total TEWI was due to the direct impact of the CFC 12
refrigerant used. HFC 134a has a GWP that is less than 20% of the GWP of CFC 12,
hence direct emissions from HFC refrigerators are only about 1% of the total
(assuming no change in efficiency). The energy efficiency of the unit is of crucial
importance. A recent report (Source Greenpeace 2) outlined the following potential
areas for reducing emissions from domestic refrigerators and freezers:
Improvement
Potential Saving (%)
Increasing insulation
More Efficient Compressor
Enlarge Condensing Area
Redesign Evaporator
Improve Control Thermostat
Door Gasket Improvement
Use HCs instead of HFCs
30
15
5
5-10
4-6
3
1
This data clearly shows the excellent efficiency opportunities and the small impact of
refrigerant substitution. Also, data from Energy Labels used on domestic refrigerators
and freezers (required by EC Regulations) show enormous variation of efficiency for
currently available models. The best category uses 60% less energy than the worst.
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It is reasonable to assume a minimum
potential of 40% improvement in
efficiency for domestic refrigeration.
Scenarios 2 and 3 show little emission
improvement because there are few
‘retrofit’ opportunities with existing units.
Scenario 4 shows a massive improvement
due to
efficiency.
With further
development of technology there may be
potential for at least another 10%
improvement in Scenario 4. Scenario 5
only shows a further 1% improvement.
Figure 5: Domestic refrigeration
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
Sector 2. Small Commercial Refrigeration
This category includes a wide range of equipment found in retail premises. Examples
include chilled and frozen display cases in food shops and petrol garages, small cold
stores in hotels and restaurants, cellar coolers and bottle coolers in pubs and bars etc.
Many of these small commercial systems are factory built hermetic units. They have
similar characteristics to domestic systems i.e. small refrigerant charge, low leakage
and good potential for energy efficiency. The larger systems in this category (e.g. cold
stores, cellar coolers and display cases in larger shops) are of a ‘distributed refrigerant’
design (see Table 1 in Section 3).
These systems have a large refrigerant
charge and are constructed on site. The
potential for leakage is quite considerable.
Historical leakage levels are high and
there is good potential for leakage
reduction (2). Energy efficiency can be
significantly improved through both
technical and management measures (3).
Further improvements for leakage and
energy efficiency are likely for new
systems (4). A move away from HFCs
gives only a small improvement, because
distributed systems must use HFCs (5).
Figure 6: Small Commercial
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
Sector 3. Large Commercial (Supermarket) Refrigeration
Large supermarkets are one of the most important refrigeration sub-sectors. A modern
supermarket uses 2 large distributed refrigerant systems, for low temperature and
chilled requirements. Refrigerant is piped to numerous display cases in the store and to
small cold stores in non-public areas. Refrigerant charge can be in excess of 1 tonne
and there are long runs of copper pipework connecting the display cases to the plant
room. Historical leakage levels have been very high and there is plenty of potential for
improvements to both leakage and energy efficiency.
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This is a sector where it could well be possible to achieve reduced emissions by
switching to secondary refrigeration systems. The use of a secondary refrigerant loop
will considerably reduce systems charge and % annual leakage rates. It will also
ensure that the public is not exposed to a risk of a refrigerant leak. However, it may
lead to lower efficiency, as the secondary loop will necessitate extra pumping power.
The options for improvement are detailed
opposite. Replacement with HFCs and less
leaky systems (2), is the least expensive
option. Energy efficiency improvements
of around 25% should be achievable with
existing types of system (3). Optimised
secondary loop systems with lower
refrigerant charge and with lower leakage,
using HFCs (4) or ammonia (5) give
excellent
potential.
Again
this
demonstrates that it is the indirect
emissions which are the most important to
address, particularly once leakage is
reduced
Figure 7: Supermarkets
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
Sector 4. Industrial Refrigeration
This is another large and important refrigeration sub-sector. It includes a wide range of
designs and applications, many of which are in the food, drink, chemicals and
pharmaceuticals industries. The sector was the only one to make use of ammonia and
HCs prior to 1990. There is a mixture of distributed refrigerant and central
chillers/secondary refrigerant systems in use. Distributed ammonia systems containing
several tonnes of refrigerant are not uncommon in the food and cold storage industries.
This illustrates that safety issues can be addressed in an industrial environment where
staff can be trained how to react if a large ammonia leak occurs.
Whilst the leakage performance of
existing ammonia and HC systems is
already reasonable, many industrial FC
systems have high levels of leakage which
could be improved (2). Energy saving
potential is good for all categories of plant
(3). There is some scope for additional
efficiency and leakage improvements for
new plant (4). A move away from HFCs is
also possible (5). The industrial sector also
has a number of significant opportunities
for cooling load elimination or load
reduction.
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Figure 8: Industrial
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
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Sector 5. Building Air Conditioning
This large sector includes very small systems in houses and offices, larger distributed
refrigerant systems (mostly used in offices, hotels etc.) and central chilled water
systems.
Average leakage rates in 1990 were around
16% per annum. Starting from this 1990
baseline (1), leakage rate can be reduced to
4% per annum representing current practice
(2). Efficiency is also an area where big
improvements can be made. Some easy
improvements are achievable (3). Leakage can
be reduced to 1% in best practice situations
and considerable further efficiency gains made
(4). Finally, in some cases where safety
considerations allow, a shift away from HFCs
is also possible (5).
Figure 9: Building A/C
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
Sector 6. Mobile Air Conditioning
At present mobile air conditioning has a very poor environmental performance. The
fuel consumption of a car with a/c is increased by 15-25%. It is estimated that around
30% of the refrigerant is lost each year (Source - EU Report). Discussions with a
major European car manufacture determined that current systems are approximately
50% less leaky than those in use in 1990. However, whilst a well maintained and
cleaned car may expect to retain its refrigerant charge for around 8 years, one exposed
to corrosion from road salt can lose its charge after as little as two years.
Efforts are being made to improve both
leakage (2) and efficiency (3), but
improvements will be offset by the likely
increase in market for these systems.
Safety issues may preclude the use of
flammable refrigerants. Corrosion from
road salt and accident damage may limit
the scope for further leakage reduction (4).
Tests on the suitability of CO2 as a
refrigerant are currently being conducted.
It is likely that CO2 systems would be
heavier and less efficient than HFC
systems, thus a move away from HFCs
may increase the indirect emissions.(5)
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Figure 10: Car A/C
100
80
60
Indirect
40
Direct
20
0
1
2
3
4
5
Scenario Number
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11.
HISTORICAL AND FUTURE GLOBAL WARMING IMPACT
In this final section we combine the results of the sectoral analysis in Section 10, to
present the potential for GW emission reduction in refrigeration and air-conditioning.
Great care must be taken when analysing historic emissions figures. Retrospective
figures for greenhouse gas emissions paint a very confusing picture, since CFCs and
HCFCs are often ignored. The rationale for this is that the substances are being banned
from use under the Montreal Protocol and 1990 usage is not relevant. This is a very
questionable approach and disguises the real improvements made in the refrigeration
(Source IIR). Ignoring the CFC/HCFC contribution to the 1990 baseline is no more
logical than ignoring fuel usage from a type of vehicle no longer allowed under safety
legislation!
Since 1990, all the FC user industries have made great strides in reducing emissions of
greenhouse gases. The GW emissions of FCs produced in the EU, expressed in
Mtonnes CO2 equivalent, fell from 1100 in 1990 to just 200 in 1995.
Direct Emissions from Refrigeration
By implementing the technical improvements outlined in this document, the
refrigeration industry will be able to reduce the direct emissions impact of
refrigeration by almost a factor of ten by the year 2010. Figure 11 shows the potential
fall in direct emissions for all refrigeration and air-conditioning systems based on
Scenarios 4 and 5 described in Chapter 10.
Mtonnes CO2 equivalent
Figure 11 Direct GW Impact of
Refrigeration
250
200
150
100
50
0
1990 (S1)
2010 (S4)
2010 (S5)
Year and Scenario Number
It is clear that the potential is excellent in both cases. Under Scenario 4, which
assumes widespread use of HFCs an 85% reduction is possible. The total direct GW
emissions of refrigerant from the EU, expressed in Mtonnes CO2 equivalent, would
fall from around 200 in 1990 to just 30 by 2010. Scenario 5, based on almost complete
substitution of FCs with ammonia and HCs gives a 98% reduction. However, HFCs
will not be replaceable in all cases, due to safety or efficiency constraints. Taking
indirect emissions into account (see figure 13) there is little difference between the
GW impact of Scenarios 4 and 5.
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Indirect Emissions from Refrigeration
The indirect emissions due to refrigeration are also likely to fall over this period, but
by a smaller amount. The technical improvements outlined in Section 8 are capable of
reducing energy requirements by at least 50%. However, this saving must be balanced
against the likely increase in the market for refrigeration systems, particularly in the
commercial and car air conditioning sectors. In total, an indirect emissions reduction
of around 25% by the year 2010 seems likely. Figure 12 below shows no difference
between the indirect emissions for Scenarios 4 or 5. The impact of refrigerant selection
is regarded as negligible on energy efficiency. There are many ‘market uptake’
assumptions built in to our efficiency estimates which would potentially have a much
larger impact on overall indirect emissions than the energy efficiency differences
attributable to use of the alternate refrigerants.
Figure 12
Indirect GW Impact of Refrigeration
Mtonnes CO2 equivalent
160
140
120
100
80
60
40
20
0
1990
2010 (S4)
2010 (S5)
Year and Scenario Number
Overall Potential for Refrigeration and Air-conditioning
Combining the direct and indirect effects we can see the overall potential for
refrigeration GW impact in Figure 13.
Figure 13 Overall GW Impact for
Refrigeration
Mtonnes CO2 equivalent
400
350
300
250
Indirect
200
Direct
150
100
50
0
1990
(S1)
2010
(S4)
2010
(S5)
Year and Scenario Number
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The figure clearly illustrates the excellent overall potential. It also emphasises the
relatively small difference between Scenarios 4 and 5.
Comparison with an Energy Using Sector
The reduction potential for refrigeration and air-conditioning is particularly impressive
when viewed in comparison to likely emissions over the next 20 years from other
sectors such as transport.
From 1990 to 1994, the period for which figures are available, only two sectors,
refrigeration and fossil fuel electricity generation have made major reductions in
greenhouse gases emitted. Emissions from industry has remained broadly constant,
whilst the emissions from the transport sector rise inexorably. Figure 14 details the
predicted contributions from transport in the EU. These figures are extrapolated from
UK Government predictions for the UK (Source UK Climate Change). It is assumed
that trends in UK transport emissions broadly mirror those of the EU as a whole.
Figure 14 Predicted GW Emission
from Transport in the EU
Mtonnes CO2 equivalent
350
300
250
200
150
100
50
0
1990
2000
2010
Year
Whilst significant efficiency improvements are expected in transport, the GW
emissions from transport continue to rise due to market growth. For refrigeration,
which will also experience some market growth, GW emissions are predicted to fall
rapidly, mainly due to improvements in leakage rates and improvements in the energy
efficiency of the systems.
Conclusions
By the year 2010, the contribution of refrigeration to total global warming emissions
may have fallen from 7% in 1990 to just under 3%. This assumes that total emissions
due to human activity can be stabilised at 1990 levels, a situation that is still not clear.
This large reduction assumes widespread use of HFC refrigerants. It will be achieved
through the sensible use of efficient refrigeration systems and the selection of the most
appropriate, safe and energy efficient refrigerant for each application.
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APPENDIX 1 GLOSSARY OF TERMS
CFC
Chlorofluorocarbon, a member of the FC family containing only chlorine,
fluorine and carbon.
Distributed systems Refers to refrigeration systems in which the primary refrigerant is
circulated around a building, factory or process to deliver cooling.
FC
Fluorocarbons - a family of chemicals manufactured by replacing hydrogen
atoms in HC molecules with fluorine or chlorine
GWP
Global warming potential, compared to the GWP of CO2 which is defined as 1.
All GWP figures used in this report are based on the 100 year time horizon.
GWP tonnes
A measure of global warming impact obtained by multiplying the tonnes of
emission of a gas by its GWP.
Hermetic system
Refers to a hermetically sealed refrigeration system with an all welded
construction. There are no gaskets or rotating seals.
HC
Hydrocarbons - a family of chemicals containing hydrogen and carbon.
HCFC
Hydrochlorofluorocarbon, a member of FC family containing hydrogen,
chlorine, fluorine and carbon.
HFC
Hydrofluorocarbon, a member of the FC family containing only hydrogen,
fluorine and carbon.
ODP
Ozone Depletion Potential, compared to ODP of CFC11 which is defined as 1.
OEL
Occupational exposure limit, a measurement of toxicity based on the
concentration level permissible in areas with long term human occupation.
Secondary systems
Refers to refrigeration systems in which a secondary fluid such as water
or glycol solution is cooled by a primary refrigerant and then circulated
around a building, factory or process to deliver cooling.
Specific refrigerant charge The ratio of the quantity of refrigerant contained in a system
divided by the cooling duty (kg/kW).
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APPENDIX 2 REFERENCES
AFEAS
“Energy and Global Warming Impacts of CFC Alternative Technologies”,
AFEAS and US DoE, 1991
BS 1
BS 4434 “Safety and environmental aspects in the design construction and
installation of refrigerating appliances and systems”, British Standards
Institute, 1995
EC DGIII
“HCFCs and their alternatives in the European Union”, EC DGIII Report, 1997
EEBPP 1
UK DoE Energy Efficiency Best Practice Programme (EEBPP), Refrigeration
Market Strategy Report, 1992
EEBPP 2
UK DoE EEBPP, Good Practice Guide 36, “Commercial Refrigeration: Energy
Efficient Operation and Maintenance”
EEBPP 3
UK DoE EEBPP, Good Practice Guide 37, “Commercial Refrigeration: Energy
Efficient Design”
EEBPP 4
UK DoE EEBPP, Good Practice Guide 42, “Industrial Refrigeration: Energy
Efficient Operation and Maintenance”
EEBPP 5
UK DoE EEBPP, Good Practice Guide 44, “Industrial Refrigeration: Energy
Efficient Design”
EEBPP 6
UK DoE EEBPP, Good Practice Guide 59, “Energy efficient design and
operation of refrigeration compressors”
EU Report
Workshop on EU Policies and Measures on Climate Change 29 May 1997. Paper on EU Reduction Potential of Fluorocarbons - p6.
Greenpeace 1 “Hydrocarbons and Other Progressive Answers to Refrigeration” Proceedings of the 1995 International CFC and Halon Alternatives Conference,
Washington DC, October 1995. p19
Greenpeace 2 ibid p114 -117
ICI
Report by McCulloch & Midgeley 1997
IEA
International Energy Agency Heat Pump Programme, Report No HPP AN 20 1
IIR
International Institute of Refrigeration, 12th Informatory note on fluorocarbons
and refrigeration, 1997
IOR
UK Institute of Refrigeration, Refrigerant Emissions Code of Practice, 1996
UK Climate Change
Climate Change The UK Programme - pub HMSO (Her Majesty’s
Stationary Office) 1997.
UK DoE 1
CFCs in the UK Refrigeration and Air-conditioning Industry, HMSO, 1992
UK DoE 1
UK Use and Emissions of Selected Halocarbons, SF6 and NF3, HMSO, 1996
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