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Climate-friendly alternatives to HFCs and HCFCs

To avoid use and emissions of both hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs), a variety of climate-friendly, energy efficient, safe and proven alternatives are available today. In fact, for most applications where HFCs and HCFCs are still used in the world, more climate friendly alternatives could potentially be used.  However, due to different thermodynamic and safety properties of the alternatives, there is no "one size fits all" solution. The suitability of a certain alternative must be considered separately for each category of product and equipment and in some cases also taking into account the level of ambient temperature at the location where the product and equipment is being used.

 

The climate impacts of a substance is commonly expressed as the global warming potential (GWP); the lower the GWP, the more climate-friendly. The GWP values of the various HFCs or HCFCs are generally in the thousands. Conversely, GWPs of climate-friendly alternatives are much lower. The most commonly used alternatives to HFCs and HCFCs and their characteristics are listed in the table below.

AlternativeGlobal Warming Potential (GWP)Properties to be addressedCommercial availability
Hydrocarbons3-5FlammableImmediate
CO2 (R744)1High pressureImmediate
Ammonia (NH3, R717)1ToxicImmediate
Water (R718)1No risksImmediate
R32 (an HFC)675Mildly flammableImmediate
HFOs4-9Mildly flammableImmediate/Short-term
R32-HFO blends200-400Mildly flammableMid-term

When seeking alternatives to HFCs and HCFCs in specific applications, it is the total greenhouse gas emissions linked to the use that counts. Hence, suitable climate-friendly alternatives must show sufficiently high energy efficiency so that the reduction in direct emissions from the alternatives to HFCs and HCFCs is not offset by higher indirect emissions from energy use

Today most of the HFCs are used in refrigeration and air conditioning (AC) equipment. In developing countries (Article 5 countries under the Montreal Protocol), R22 (an HCFC) is still the most important refrigerant currently used in this sector. In those countries, demand for refrigerants is expected to increase significantly in the short and medium term, to satisfy expected growth in the use of AC and supermarket refrigeration, in particular.

2015 Refrigerant consumption in developing countries

 

2015 Refrigerant consumption in developing countries
(Article 5 countries under the Montreal Protocol)
 
private fridges, freezes1%
commercial plug-in fridges6%
small condensing units <5kW6%
condensing units >5kW6%
centralised supermarket refrigeration6%
large industrial refrigeration4%
displacement chillers5%
centrifugal chillers2%
AC portable/windows7%
AC single split <7kW29%
AC single/multi split >7kW19%
AC cars7%

A number of studies on the availability of alternatives at sub-sectoral level have been carried out by various renown experts, including an extensive analysis carried out for the European Commission by the independent consultant Oeko-Recherche in the context of developing the new EU F-gas Regulation.

The preparatory analysis for the F-gas Regulation showed that the replacement of HFCs by climate-friendly alternatives will not only reduce direct emissions of HFCs by two-thirds of today's levels, but also improve energy efficiency overall, leading to additional greenhouse gas emission savings. Research and development is progressing rapidly in this area and since the study finished 2011 even more and less costly alternatives have reached the market.

In 2014 another study for the European Commission, Oeko-Recherche looked at the particular question of availability of suitable alternatives under high ambient temperatures (traffic light analysispdf(258 kB) Choose translations of the previous link  ). These findings are explained below in the form of traffic lights as to whether specific alternatives are suitable in different types of equipment and products.

IconDescription
LowEnergy efficiency too low or cost too high compared to other alternatives
OkEnergy efficient. Safe. But costly and no short term availability
HighEnergy efficiency high. No or acceptable additional cost. Short term availability

Domestic refrigeration

Hydrocarbon refrigerants have been used for many years in refrigerators and freezers in people`s homes throughout the world. Over 90% of new appliances nowadays contain hydrocarbon refrigerants. These appliances are very efficient also under high-ambient temperatures.

Global SituationHC
(direct)
HFOR32R32-HFO blends
GWP34675200-400
Domestic RefrigerationHighLowLowLow

Commercial refrigeration

Plug-in equipment used in small stores and supermarkets such as vending machines that rely on hydrocarbons and CO2 has been available for some years throughout the world. In large supermarkets refrigeration ("centralized systems"), CO2 cascade systems are an alternative to common HFC systems in cold and moderate climates. Hydrocarbons also have proven to be highly efficient alternatives in most applications under high-ambient temperatures, except for larger condensing units.

High-ambient temperaturesHC
(DX or cascade)

HFO
(DX or cascade)

R32-HFO blends
GWP< 6< 8200-400
Stand-alone eq.HighOkLow
Cond. Units < 5kWHighLowOk
Cond. Units > 5kWLowHighHigh
Centralised systemsHighHighOk

Industrial refrigeration

In industrial refrigeration such as large cooling facility for food processing, ammonia systems have been used for many years. High-ambient temperatures do not result in lower energy-efficiency of ammonia systems.

Global situationHCNH3HFOR32-HFO blends
GWP< 60< 8200-400
Large industrialLowHighLowLow

Stationary air conditioning

Hydrocarbons are safely used as alternative refrigerants in room air conditioning systems in several countries such as India and China. For larger systems, pure R32 with a medium-high GWP can be employed as alternative. In chillers, the use of hydrocarbons and ammonia are safe and energy-efficient alternatives to HFCs and HCFCs, both under moderate and high-ambient temperature conditions. Newly developed hydrofluoroolefins (HFOs) are already commercially available for use in very large (centrifugal) chillers.

HC
(direct)
HC
(indirect)
HFOR32R32-HFO blends
GWP33< 10675200-400
Portable/WindowsHighLowLowLowOk
Single Split < 7kWHighLowLowLowOk
Split/Multi. > 7kWLowLowLowHighOk
HCNH3HFOR32R32-HFO blends
GWP30< 8675200-400
Chiller < 150kWHighLowLowLowHigh
Chiller > 150 kWHighHighLowLowHigh
CentrifugalLowLowHighLowLow

Mobile air conditioning

The refrigerant HFC-134a used so far in air conditioning of cars is being substituted in new car models as a consequence of the European Directive on mobile air-conditioning systems (MAC Directive). Alternative refrigerant options include CO2 and the HFO refrigerant called R1234yf, which has been introduced in certain car models recently.

GlobalCO2HC
(direct)
HFOR32R32-HFO blends
GWP134675200-400
MACHighLowHighLowLow

Foam blowing

Polyurethane (PU) foam: Only few PU foam products are today still manufactured with HFC blowing agents. The vast majority rely on hydrocarbons such as pentane or cyclo-pentane without loss in energy efficiency. Non-flammable blowing agents like HFCs are mainly used for on-site application of PU spray foam. For this and some niche applications unsaturated HFCs are already commercially available.

Extruded polystyrene (XPS): Major manufacturers of XPS insulation boards have already converted their production facilities to organic solvents or HFOs. The remaining users of HFCs are currently switching to HFOs. Energy efficiency of HFOs is said to be better than that of HFCs.