The first major phase change for refrigerants has not even been completed yet and already many are urging yet another. The long, hard, costly journey away from ozone-depleting chlorofluorocarbons (CFCs), which began in the early 90s, continues, with a 2010 step down in production and eventual phase out of hydrochlorofluorocarbon (HCFC)-22 refrigerant in new HVAC/R applications. But soon after hydrofluorocarbons (HFCs) became the established alternative, many in Europe began urging yet another costly, arduous trek – away from HFCs and toward “natural refrigerants.” The igniter behind all the commotion is the hot topic of the day – global warming.

HFC refrigerants have no chlorine on the molecule, which gives them a zero ozone depletion potential (ODP) versus chlorine-containing refrigerants like CFC-12 (ODP=1) or HCFC-22 (ODP=0.05). But the new environmental concern in the air, global warming, casts HFCs in a less favorable light due to their relatively high global warming potential (GWP) values.  While the change from CFCs to HFCs drastically reduced refrigerant-related contribution to global warming (for example, one kg of CFC-12 has the same global warming contribution as 8500 kg of CO2 while one kg of HFC-134a is equivalent to 1400 kg of CO2), the intensifying focus on global warming has created pressure to find alternatives with even lower GWPs including use of natural refrigerants like CO2, hydrocarbons and ammonia which have no ODP and very low GWP.

While many European air conditioning and refrigeration manufacturers are hot on natural refrigerants, North American OEMs are cool to them. On this side of the pond, the industry is satisfied with HFCs. The industry here is happy with HFCs performance and their ability to work with most of today’s equipment designs. More importantly, OEMs here are leery of investing in another costly conversion adventure for what they see as negligible return.

A Coca-Cola cooler charged with carbon dioxide refrigerant.

“There is quite a divide between and across the Atlantic,” says Daniel Colbourne, a refrigeration consultant with Refrigerants, Naturally!, a European-based initiative promoting the use of natural refrigerants. When the CFC phase-out was being considered, natural refrigerants were considered as a replacement, but the alternatives that were considered – ammonia and hydrocarbons – are flammable and toxic and in North America this led to safety concerns and litigation fears, he says. Those refrigerants were put on the back burner while HFCs became the prominent material. In Europe R&D on these fluids and their implementation were ongoing. In fact, more than 200 million refrigerators in Europe are charged with isobutane, a natural hydrocarbon refrigerant, Colbourne says.

Still, HFCs are the dominant alternative to CFCs because they are a proven and established efficient technology. HFC-134a has replaced CFC-12 and is now used extensively in refrigerators and mobile air conditioners (MAC). Other HFCs, like HFC-410a are replacing HCFC-22 in unitary air conditioning systems and HFC-404a is the alternative for commercial refrigeration applications. At the recent AHR Expo, a number of HVAC/R companies released new equipment using HFC-based refrigerants including Amcor, HeatCraft, Johnson Controls, and Lennox.

And, the use of HFCs is growing, especially as the final deadlines for CFC and HCFC phase out rapidly approaches. Kevin O’Shea, North American marketing manager for DuPont Refrigerants, says that today’s HFC products such as DuPont’s Suva R-404A are environmentally acceptable because they have no ODP, they work efficiently with little energy waste, and can use existing design platforms.

Enlarge this picture The phase out of HCFC-based refrigeration has been accelerated."

Echoing this idea is Peter Geosits, Americas Commercial Director for INEOS Fluor Americas in St. Gabriel, La., who says that R-134a, a refrigerant that his company sells, is a non-ozone depleting, non-toxic fluid that can be used in a range of applications today from automotive A/C to residential refrigerators and air conditioners.

For those worried about GWP, Geosits says that the industry has already reduced GWP with the HFC products. “CFCs were very potent global warmers and when replacing them with HFCs there was a reduction in GWP on the order of 7 to 8 fold,” he says.

Another manufacturer that believes that there is a place for HFC refrigerants is Arkema, a Paris-based refrigerant supplier with U.S. operations based in Philadelphia. The company produces R-410a refrigerant, which the company markets as Forane 410A. R-410a is a blended-HFC refrigerant that uses a 50/50 blend of R-32 and R-125, and is a replacement for R-22. R-32 is a highly efficient refrigerant, but slightly flammable, and R-125 is completely non-flammable, which helps to neutralize the flammability issues regarding R-32, says Craig Thomas, market manager for Arkema’s North American refrigerants. The R-32 is made at the company’s new plant in Calvert City, Ky., and in 2010 Arkema will make the R-125 component in China in a joint venture with Daikin.

Arkema storage facility.

Forane 410A has zero ODP and a GWP of 1,890. It has a boiling point of –61.6 DegF. He adds that R-410A does have a higher operating pressure than R-22, and may require changes to compressors, condensers and other components.

While Arkema’s product does have a GWP rating, Thomas says that it is a highly efficient product, which cuts down on indirect emissions, and is safe and non-toxic. “GWP is obviously on our minds because fluorocarbon chemicals have a GWP and they might be a target for a phase out,” says Thomas. “And, we are developing low-GWP products. But, the products we have now are good products for today’s users. Not for 10 or 15 years down the road.”

The group Refrigerants Naturally! is pushing for faster implementation of natural refrigerants. The group was cofounded by The Coca-Cola Company, Unilever and McDonalds, and now counts PepsiCo, Carlsberg and IKEA as members. According to Linda Ederberg of the Refrigerants, Naturally! Secretariat, natural refrigerants are cheap, easily available, and are climate and ozone friendly. She says that the practice among the members of Refrigerants, Naturally! has demonstrated the safe use of natural refrigerants and that they can be more efficient than HFCs.

Enlarge this picture In testing its newly redesigned vending machines and coolers, Coca-Cola found energy savings varied depending upon ambient temperature.

The natural refrigerants family includes carbon dioxide, ammonia and hydrocarbons, which can include isobutane and propane.

Carbon dioxide has no ozone depletion potential (ODP = 0) and negligible direct global warming potential when used as a refrigerant in closed cycles. It is more efficient at lower ambient temperature. (HFCs tend to be more efficient at higher ambient temperatures relative to CO2.) Carbon dioxide has a GWP of 1 as compared to 1,430 for R-134a.

Ammonia has no ODP and zero GWP. Ammonia is toxic and flammable, but these characteristics have proven to be controllable. In the U.K. and elsewhere in Europe, ammonia is often used in a secondary coolant system in which the material is used in an externally located chiller, which cools a secondary refrigerant such as a glycol, brine, or CO2, which is then pumped around a secondary circuit to display cases and cold rooms. Supermarkets in the UK such as Tesco, Sainsbury’s, ASDA/Wallmart, and Marks & Spencer have committed to such an approach, says Colbourne.

Hydrocarbons are flammable refrigerants and include propane (R-290), isobutane (R-600a) or hydrocarbon blends as working fluids in their equipment. The hydrocarbon refrigerants have no ODP. The GWP rating is considered negligible. Most hydrocarbon refrigerants have a GWP of <3. They are often used in applications that require low temperature levels, which is one of the reasons that companies such as Unilever selected the hydrocarbon, propane.

Suppliers of fluorocarbons, or F gases, agree that natural refrigerants have direct low GWP emissions, but claim that that doesn’t tell the whole story. They claim that natural-refrigerant based systems are less efficient, and thus require more energy to run them. They point to Life Cycle Climate Performance as a better measure of global warming potential because it takes into account both direct and indirect effects. An appliance with a low-GWP hydrocarbon refrigerant can still have a total high GWP value if it is inefficient and causes more indirect CO2 emissions at the power plant.

According to a policy statement from INEOS Fluor regarding refrigerants, the main environmental impact of most refrigeration systems is the amount of energy that they use. On average, 80 percent of the climate impact from refrigeration and air conditioners is caused by indirect emissions of carbon dioxide. The energy efficient properties offered by HFCs are a significant advantage to designers, the company says.

Fluorocarbon suppliers also point to some of the engineering challenges involved with natural refrigerants, such as the high operating pressure required for carbon dioxide, which would require redesign of cooling systems. C02 has dramatically higher operating pressures even compared with other natural refrigerants and these differences grow with increases in ambient temperature. For instance, at –69 DegF, the C02 pressure is 76.6 psia, while ammonia is 4.078. At –40 DegF, the CO2 pressure is 145.69, as compared to 10.093 for ammonia.

Still, HFC refrigerant suppliers are aware of the GWP issues and a number of companies are already working to develop low-GWP refrigerant products. These products will initially be used for the automotive industry in the European Union, an industry that faces an EU deadline of 2011 to phase out HFC -134a refrigerant use in cars. INEOS Fluor is working on such a refrigerant that it believes will have a GWP below the 150 threshold for automotive refrigerants used in new cars that was set by the European Union’s F-Gas regulation.

In March 2007, DuPont announced a joint development agreement with Honeywell to develop a low-GWP refrigerant for use in the automotive air conditioning industry in Europe. They are working with automotive OEMs on the development and commercialization of hydrofluoro-olefin (HFO)-1234yf, which would meet the European Union’s 2011 MAC Directive and could potentially replace HFC-134a in MAC systems. The HFO-1234yf has a GWP of 4 so it is close to C02, says O’Shea.  “The results are very similar to R-134a, so we could use it without having to make drastic changes to the car’s design that would add weight and create servicing challenges,” O’Shea says. “This same technology could also be applied eventually to stationary air conditioning and refrigeration applications.”

Despite these efforts, the drumbeat to replace HFCs with natural refrigerants can be heard. Denmark, in 2007, passed a law that limits an HFC charge and Austria is following suit. In the U.S., California has targeted HFC emissions from cars and commercial refrigeration. According to a report by the California Air Resources Board, approximately 500,000 vending machines are in use in California that have leak rates of about 30 percent per year or about 2.7 MMTCO2 (million metric tons of carbon dioxide). These could be a target application for a low GWP refrigerant.

Perhaps the biggest push is coming from those companies that come closest to dealing with consumers such as Unilever and The Coca-Cola Company.

The Coca-Cola Company is working to phase-out HFC refrigerant-based equipment and replace it with CO2 equipment. The company is focusing on emissions from its vending machines and coolers after an audit of their carbon footprint. What they found surprised them, says Bryan Jacob, energy and climate protection manager for The Coca-Cola Company. They found that equivalent CO2 emissions from this type of equipment far outstripped emissions from manufacturing and fleet operations. In 2000, more than 15 million metric tons equivalent of carbon dioxide was released from this source as compared to about 5 MMT from the company’s 900 manufacturing operations, and 3 MMT from the company’s 200,000 diesel-powered trucks.

This led the company into making cabinet and refrigeration efficiency a priority. They looked at all of the refrigerants on the market and chose CO2 after conducting a survey analyzing the worldwide regulatory landscape. They felt that CO2 would be the best refrigerant in the long-term.

In efficiency testing, natural refrigerants did better than they initially expected, says Jacob. He says that the CO2 systems compared to the HFC systems were 4 to 7 percent better. Their testing found that CO2 systems work better at somewhat lower ambient temperatures, below 35 DegC, than did the HFC systems.

While Coca-Cola chose CO2, Unilever chose the hydrocarbon, propane. In 1994, Unilever, one of the world’s biggest ice cream manufacturers, was one of the first company’s to transition to HFC-based freezer cabinets and have already moved to phase these systems out. By the end of 2007, about 200,000 hydrocarbon-based freezer cabinets were installed throughout Europe. According to the company, lab tests suggest these hydrocarbon cabinets are energy efficient, using up to 12-17 percent less energy than previous units. According to Alan Gerrard, Unilever’s Global Project Leader for this project, field-testing showed efficiency gains of around 9 percent.

While the company had planned all along to phase out HFCs, it was uncertain about which natural refrigerant to choose. After testing many alternatives, they decided to back propane for a couple reasons. As an economic decision, they chose propane because at the time there were a large number of low-cost compressors on the market that could handle the natural refrigerant as compared to CO2 compliant compressors, which were not as available and cost more.

The second, more important reason, dealt with thermodynamics. Gerrard says that to reach the operating temperature that they require (–18 DegF) using a CO2 system would have meant using two compressors in order to reach the same energy efficiency as the hydrocarbons.

When choosing propane, they were initially concerned about safety issues. “The first question we had was the flammability of the refrigerant,” he says. “But, we knew that isobutane and propane have approximately the same flammability rating and that in the year 2000, there were about 120 million domestic refrigerators and freezers using isobutane and we weren’t aware of any accidents.”

Unilever undertook a number of risk assessments before the introduction of the hydrocarbon cabinets.  The company also did leak testing and found that the leak rates for hydrocarbons in operation were “very, very low,” he says, in line with HFC refrigerated cabinets.. Leak rates are in the range of grams per year, he says, and at this rate it was highly unlikely that flammable mixtures could be formed.

Unilever’s environmental work is not just a matter of good citizenship, but economics and it may point to a new paradigm for the industry – making design and engineering decisions based on the impact of a consumer’s awareness of how well a company acts as an environmental steward.

“In the early stages of the program, the consumer was less strongly in mind,” says Gerrard, “But it has become clear to us that consumers are demanding more from our products than just quality and value, they are also looking for companies that are aware of their impact on society and the environment.”

For more information:

Arkema Inc. email: stan.howard@arkema.com

DuPont Refrigerants email: Ellen.G.Pressley@usa.dupont.com

Ineos Fluor email: KleaUSwebmail@ineosfluor.com