Refrigeration Main Challenges

Didier COULOMB
International Institute of Refrigeration (IIR)
www.iifiir.org

1. Refrigeration is increasingly necessary

1.1. Refrigeration is necessary to mankind

Temperature is a magnitude and a key variable in physics, chemistry and biology.

It characterizes the states of matter in liquid, solid and gaseous phases and is therefore essential in material applications.

It is vital to all living beings and each living being (bacteria, plant, animal) has a temperature range within which it can live.

Temperature governs whether pathogens can develop, survive or not. Foodstuffs and health products are thus often chilled or frozen.

Refrigeration is everywhere, in:

•         Cryogenics (petrochemical refining, the steel industry, thespace industry, nuclear fusion…)
•         Medicine and health products (cryosurgery, anaesthesia, scanners, vaccines…)
•         Air conditioning (buildings, data centres…)
•         The food industry and the cold chain
•         The energy sector (including heat pumps, LNG, hydrogen…)
•         Environment protection (including carbon capture and storage), public works, leisure activities…
 

1.2. The Needs are increasing, particularly in developing countries

 We need to keep a few facts in mind:

– 1600 deaths/year in the USA (1), at least partly associated with temperature control, are due to pathogens. According to the World Health Organization (2), refrigeration and improved hygiene have reduced stomach cancer by 89% in men and 92% in women, since 1930 in the USA. Figures would certainly be much higher in less developed countries where there is huge leeway for progress.

– There is an increase in global population, particularly in Africa and South Asia (9,3 billion in 2050, 8 billion in developing countries) (3)

– 70% (50% now) will be in urban areas (doubled figures in developing countries) (3) and this will increase the need for cold chains, because of longer distances between production and commercialization sites and because of increasingly westernized models (meat,… )

– 1 billion people are undernourished (4); 23% of food losses are caused by a lack of refrigeration in developing countries (vs. 9% in developed countries) (5). The refrigerated storage capacity in developed countries is tenfold the refrigerated storage capacity per inhabitant in developing countries (5).

– There are needs for better health everywhere (good cold chains, air conditioning), particularly because of an ageing population.

This increase in emerging and developing countries will increase the impact on the environment.

 
2. Energy and the Environment are increasing challenges for the future

2.1. Refrigeration is a major energy consumer

Refrigeration, including air conditioning, represents 15% of global electricity consumption. And this figure will increase (The Netherlands: already 18%…). Refrigeration issues are clearly linked with electricity issues, which are:

– Global warming because of CO2 emissions (electricity production depending on fossil fuels): we need to take into account the TEWI (Total Equivalent Warming Impact), and the LCCP (Life Cycle Climate Performance) of the refrigerating equipment (the IIR recently built a Working Party to measure it)

– The price of electricity will increase (new sources of energy have higher costs)

– There is a lack of power infrastructures, particularly in developing countries

Overall system solutions (district cooling, trigeneration…) should certainly be developed and we need to review the coefficients of performance of the systems. For instance, heat pumps are considered as a renewable energy in the European Union, provided that they have a sufficient Coefficient of Performance because of their electricity consumption. There are and there will be new regulations on energy and on buildings in Europe, the USA or Japan with new constraints on energy and thus new constraints on refrigeration systems.

New sources of energy can be used, such as solar energy. Even if the coefficient of performance of solar equipment is still relatively low and if investment costs can be high, some systems are already in place and many experiments and research programmes are ongoing.

Refrigeration can also drive new sources of energy, like liquefied gases (Liquefied National Gas, Liquefied Hydrogen…).

In any case, changing a system because of refrigerant issues must take into account potential reductions in energy consumption: both issues are linked.

2.2. The impact of refrigerants on the environment

Vapour-compression systems will remain predominant in the short and medium term and thus we will require more refrigerants in the future.
 
Because of their impact on the stratospheric ozone layer, Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs) are included in the Montreal Protocol and each country (whether developed or developing) had to build phase-out plans. That issue will thus hopefully soon be behind us, apart from the bank issue (refrigerants in existing equipment to be destroyed in the future). However, the main issue of phase-out plans is the kind of refrigerating equipment which is used to replace old equipment.

There are alternative refrigerants:

– Hydrofluorocarbons (HFCs), including Hydrofluoroolefins (HFOs) have no impact on the ozone layer but they have an impact on global warming (they are included in the Rio Convention and the Kyoto Protocol)

– Natural refrigerants (ammonia, CO2, hydrocarbons, water, air) have a very low impact on global warming.

– Mixtures, combinations (cascades, secondary fluids) are being developed in order to meet the various requirements.

The following table summarizes the impact of the main refrigerants on the ozone layer (Ozone Depleting Potential = ODP) and on climate change (Global Warming Potential = GWP). Even if CFCs have a very high ODP and GWP, HCFCs and HFCs have similar impacts.

CFCs and HCFCs are mainly replaced by HFCs, which generally have a high GWP

Source: UNEP

HFCs are mainly used in refrigeration and air conditioning

Source: UNEP
 
HFCs currently represent less than 1% of CO2 eq emissions. In 2050, they will represent 7-45% (more likely 7%) of CO2 equivalent emissions.

HFCs emissions in 2050 could offset the achievements of the Montreal Protocol related to the phase-out of CFCs.

Hence, discussions are held at an international level (Montreal Protocol and Kyoto Protocol meetings) on the future of HFCs: replacing HCFCs with HFCs could be a real threat to the climate.

3. How to reduce the impact of refrigerating equipment on environment?

3.1. Various solutions

a – There are other technologies: absorption, adsorption, solar refrigeration, magnetic refrigeration, thermoelectric cooling, cryogenics (nitrogen, CO2) but they still require technological improvements (in terms of cost, energy efficiency, capacity). Thus, they are currentlyonly niche technologies.

However, many technical developments take place. IIR Conferences on adsorption-absorption technologies, on magnetic refrigeration and on cryogenics are increasingly successful and people in universities and industries from America, Europe, Asia attend them. Prototypes of magnetic refrigeration are developed in all these regions. Solar cooling is experimented in Africa as well as Southern Asia and Australia.

New solutions will be found on a mid-term perspective.

b – We can reduce leakage

Refrigerant emissions are due to leakage and poor recovery at the end of life of the equipment. Both issues can be handled and it would certainly be part of the solution on a short-term perspective.

Because of important variability within similar equipment working in similar conditions, there are margins for progress. For instance, leakage rates in the European Union which were at 30% in the 1980s are now at 5% and less.

This is part of the solution the European Union decided to implement in order to reduce fluorinated gases emissions. The F-gas regulation was adopted in 2006. It is too early to assess the impacts of this regulation on refrigerant emissions and the regulation is currently under revision. However, some advantages and backwards of such a regulation can already be seen. The aim was to strengthen the control on leakage thanks to staff training, and the certification of staff and companies handling refrigerants in stationary equipment.

Training is necessary but it is the most important difficulty and it takes time. However, reducing leakage has clear advantages in terms of savings and on safety. For instance, a draft European proposal for the review of the F-Gas regulation proposes to extend training and certification to non-fluorinated gases which could be toxic and flammable. In any case, more training of staff handling refrigerants will be necessary in the future.

c – We can reduce the refrigerant charge

The aim is the same: reducing the refrigerant charge without changing the refrigeration equipment capacity and its efficiency would reduce leakage rates. Several technologies can be used and are currently developed: secondary refrigerants, micro-channel technologies… It is also both a Greenhouse-gas emission reduction issue and a question of safety.

d – Choosing a low-GWP refrigerant

There can be several definitions of a “low-GWP” refrigerant. People generally consider refrigerants as low GWP fluids when their GWP is lower than 20: natural refrigerants (ammonia, CO2, hydrocarbons, water, air) or some HFCs called HFOs (hydrofluoroolefins). However «moderate» GWP refrigerants (for instance R32) are also chosen by companies, since their impact would be much lower in casesof leakage than some higher GWP refrigerants. (1/2 to 1/7…). In any case, several issues should be considered:

– Most low GWP refrigerants have safety drawbacks: flammability, toxicity. Some of them require very different equipment than that used with HCFCs or HFCs, because of corrosion or pressure issues. They all require adaptations of the equipment.

– Equipment energy efficiency depends on the kind of equipment, the working fluid as well as working conditions, such as climate conditions. However, solutions with natural refrigerants exist all over the world for many applications with similar energy efficiency than in most common equipment.

– Investment costs can be higher for low GWP refrigerants especially because of safety reasons. However, the cost of the fluid and the maintenance must also be taken into account.

– Numerous current technical developments on low GWP refrigerants and on new technologies are underway and constantly updated information is required.
 

Conclusion

And this is precisely the aim of this publication: to present various issues related to refrigerating equipment, various technologies, whether currently used or still under development.

(1) Head PS. et al. Food related illness and death in the United States.

Emerging Infections Diseases, 1999

(2) WHO, World Cancer Report, 2008

(3) United Nations. World Population Prospects, the 2011 revision

(4) FAO World Agriculture: Towards 2015/2030 – Summarizing Report

(5) 5th IIR Informatory Note on Refrigeration and Food: the role of Refrigeration in Worldwide Nutrition