replacing HFCs with natural refrigerants worldwide today

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Natural Refrigerants

Fluorinated greenhouse gases (F-gases) are a family of chemicals that contain fluorine. Most F-gases are very powerful greenhouse gases which contribute to global warming when emitted to the atmosphere, as they all, apart from a tiny percentage, inevitably do.
F-gases are synthetic and do not exist in the natural environment. Also, there exist no natural cycles to absorb HFC emissions. Their longevity is therefore limited only by their atmospheric lifetimes.

HFCs have been widely promoted from the early 1990s by the chemical industry as a substitute for ozone-destroying gases. HFC134a is the most widely used, and it is nearly 1500 times more potent than carbon dioxide in causing global warming.
F-gases cannot be properly and safely contained over the lifetime of the equipment, and with projected increases in use of HFCs, their contribution to global warming will amount to 45% by 2050 according to the Velders et. al. Study of 2009.
Industry data indicates that a staggering 81% of the main F-gas currently in use today (R-22) has been released into the Earth’s atmosphere.

Chemical refrigerants: history repeating

When CFCs were finally identified as the cause behind the depletion of the ozone layer the United Nations called on developed countries to sign the 1989 Montreal Protocol on Substances that Deplete the Ozone Layer designed to protect the stratospheric ozone layer. The phase out of CFCs by 2000 was seen as the only solution to avoid severe environmental and health threats.

At the time HCFCs and HFCs were thought to provide an opportunity to accelerate the phaseout of CFCs.
Clearly, HCFCs and HFCs presented several advantages: they are non-flammable fluids and can achieve comparable energy efficiency. However, with the increasing concern about global warming, Parties to the Montreal Protocol agreed in 2007 to accelerate the phase-out of HCFCs in order to further extend the climate benefits already achieved by the Ozone Treaty.

HFCs on the contrary, were believed to provide an appropriate alternative  as regards user safety and ozone depleting potential and were thus maintained.

But, increased scientific evidence has also shown that the high Global Warming Potential of most HFCs alarmingly contributes to rising sea levels, biodiversity degradation and climate catastrophes. In the end, replacing CFCs by HFCs has only displaced the problem and we now face a grave risk of undermining the substantial climate benefits achieved by the Montreal Protocol.

The Kyoto Protocol was signed with the goal of achieving "stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system".
The Kyoto Protocol establishes legally binding commitments for the reduction of six greenhouse gases (carbon dioxide, methane, nitrous oxide, sulphur hexafluoride hydrofluorocarbons and perfluorocarbons) produced by industrialized nations, as well as general commitments for all member countries.

As history repeats, the revision of the Kyoto Protocol at the end of 2011 that will take place in Durban, South Africa, must now include a phase out of HFCs to halt their damaging contribution to Global Warming. While proven climate friendly natural refrigerants exist and countries are now implementing legislation to phase down the production and use of HFCs in some applications (eg: EU F-gas regulation, EU mobile air-conditioning directive, tax measures in Scandinavian countries) no internationally binding agreement has been put forward to phase out these chemicals.

The Durban climate agreement is an unprecedented opportunity to combine phase-out of identified CO2 emitters and to create a momentum for introducing climate friendly alternatives for refrigeration systems. 
Also, unless climate and ozone-friendly substitutes are introduced in place of HFCs, the HFC emissions will undermine the substantial climate benefits of  the Kyoto and Montreal Protocols.

Natural refrigerants, an overlooked solution?

The shift from using CFCs and HCFCs to HFCs has done nothing to stem the damage to the environment.
In fact, the use of HFCs is still prevalent and contributing heavily to climate change. This is a scenario that is likely to continue for several decades unless more climate-friendly solutions are adopted. Hence alternatives, namely natural refrigerants, now need to be looked at again to mitigate some of the environmental risks linked to the use of chemical refrigerants.

Natural refrigerants are non-synthetic substances that occur in nature’s material cycles and which can and should be used as the cooling agents in refrigerators and air-conditioners. These include CO2, water, air, ammonia and hydrocarbons such as propane, butane and cyclopentane. These substances have been used as refrigerants for years but are only now beginning to replace F-gases in certain applications. The advantages that natural refrigerants possess from a climatic standpoint are telling: they do not damage the ozone layer and have a negligible impact on the greenhouse effect.

From an economic perspective, the results are just as impressive: The refrigerants themselves are inexpensive, in some cases even cheaper than HFCs. This has a beneficial impact on the initial filling of the plant as well as on the operating costs since leakage-related costs are reduced. Also, natural refrigerants are extremely energy-efficient, sometimes up to 40% more than HFCs.

In times of stricter environmental legislation worldwide on F-gases, the inexpensive disposal of natural refrigerants at the end of a refrigeration system’s lifetime presents considerable financial benefits in shifting to more climate-friendly cooling systems.

It should be noted that despite installation of a natural refrigerant system sometimes contributing to increased capital expenditure, depending on its type and capacity, these are counterbalanced by reduced overall costs.

There is not sufficient evidence to support the assumption that investment in plants using natural refrigerants are typically 10-20% more expensive than those using synthetic refrigerants.
Even where this may be the case, these costs are almost always offset by the lower expenses to run the plant with natural refrigerants.

Natural refrigerants delivering on the Montreal and Kyoto Protocols Natural refrigerants have no or very low Global Warming Potential (GWP) and zero Ozone Depleting Potential (ODP) and thus meet the prerequisites of the Montreal Protocol.They also fulfil the aims of the Kyoto Protocol in terms of reduction of CO2-equivalent emissions.

Together, R744 (CO2), ammonia and hydrocarbons could provide climate friendly cooling solutions to replace HFCs in all refrigeration and air conditioning systems today thanks to their superior heat transfer and environmental qualities.

R744 (ODP=0; GWP= 1)

R744 can be applied in most heating and cooling systems such as mobile air-conditioning (MAC) in vehicles and buses, vending machines, coolers, commercial cabinets for supermarkets, containers and climate control systems for residences. CO2 technology (R744) has also shown to be extremely efficient in heating water. This explains the success of the Japanese "Eco Cute" heat pump water heaters, which can also be combined efficiently with floor heating. As an illustration, in Japan more than 300,000 CO2 based Eco Cute units of water heaters were sold in 2006.

Ammonia (ODP=0; GWP= 0)

Ammonia refrigeration is the backbone of the food industry for freezing and storage of both frozen and unfrozen foods in many parts of the world (including fruits, vegetables, meat, poultry, fish, dairy, ice cream, beverages). In the range of 50 kW to 200 kW ammonia may be used, and for larger freezers ammonia is almost always preferred due to improved energy efficiency and reduced leakage.

Hydrocarbons (ODP=0; GWP <3)

By far the largest application for hydrocarbon refrigerant to date, hydrocarbons are successfully used in domestic refrigerators and freezers. For example, R600a (isobutane) is used in more than 400 million so-called Greenfreeze fridges and freezers worldwide. Mostly R290 (propane) is used as a replacement for the ozone-depleting substance R22 and HFCs in ice cream freezers & cabinets, commercial freezers & refrigerators (walk-in-freezers, meat freezers, salad coolers), ice cube machines, bottle coolers, vending machines, cascade supermarket refrigeration systems, or water coolers. Split system air-conditioning equipment for office and domestic use, portable AC, water-air AC, air-air AC, AC chillers, and dehumidifiers can use hydrocarbons.
Although largely ignored by policy makers to date, hydrocarbons have a long track record of safe, efficient and high performance use in mobile airconditioning systems in North America, Australia, many parts of South East Asia and other countries around the world. This strong empirical evidence of the suitability of hydrocarbons for use in servicing existing systems cannot continue to be overlooked in the urgent search for emissions abatement opportunities.

If a global agreement on climate change is to be reached and delivered successfully in Durban in 2011, then a planned phase-out of HFCs must be part of the climate goals of signatories.

Source: AFEAS Alternative Fluorocarbons Acceptability Study 2007

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