Questions and Answers

Cool for the Planet

Solstice® yf refrigerant has a fraction of the global warming impact of traditional automotive refrigerant and produces fewer CO2 emissions than both R-134a and the so-called natural refrigerants.

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Natural Refrigerants?

What are the criteria for natural vs. synthetic refrigerants?

Often, refrigerants are called “natural” if the substance also occurs in nature. This is the case with CO2. CO2 is a gas with global warming potential. It is a component of air and occurs in a concentration of 0.039 Vol% (390 ppm). CO2 can be toxic. However, the concentrations in air are too low to produce this effect. Despite its occurrence in nature, CO2 needs to be industrially produced for use as a refrigerant. Synthetic refrigerants are typically products manufactured in a chemical process.

What natural refrigerants are under consideration for mobile air conditioning?

Both hydrocarbons and CO2 (R-744), as well as R-152a have been considered as replacements for R-134a. To date, none of these refrigerants has been broadly adopted by the global auto industry for performance, cost-efficiency or safety considerations or a combination of these.

Hydrocarbons are in use in Australia. Why can’t they be used safely in the EU?

Although there is some use of hydrocarbons in auto air conditioning systems in Australia, they are not used in new cars as they have not been judged safe to use in this application by any major vehicle manufacturer. In contrast, HFO-1234yf has been thoroughly assessed by major auto manufacturers and has been judged to be safe.

What are the costs of natural fluids compared to synthetic fluids?

When we discuss cost we need to look at the total cost of the system and not just the refrigerant cost. Although the cost of CO2 is fairly low, there is a significant system cost increase for the use of CO2 in auto air conditioning. There was one value reported by GM at an SAE meeting of an additional $350. Likewise, if highly flammable hydrocarbons were used, secondary loop systems would be required to keep this material out of the passenger compartment. This would also cause a significant increase in the cost of the system and make it less energy efficient.

Does the chemical industry own IP on naturals to prevent others from using the technology?

We cannot speak for the entire chemical industry but we are not aware of any IP owned by the chemical industry that has any significant impact on the use of natural refrigerants in this application.

What are the advantages and disadvantages of naturals?

Honeywell acknowledges that under certain operating conditions and in certain applications so-called natural refrigerants can be cost-effective and efficient fluids. Several Honeywell businesses are involved in the design and maintenance of systems depending on these fluids. Honeywell is the largest supplier of air-based cooling systems in aerospace applications.

Why do some blends contain hydrocarbons?

There are some HFC/hydrocarbon refrigerant blends that have a small percentage of hydrocarbons (<5%) that are used to replace either CFCs or HCFCs that are used with a mineral oil lubricant. Due to the small amount of hydrocarbons, these blends generally remain non-flammable even under worst case fractionation. The small amount of hydrocarbons improve the solubility of these refrigerants with the existing mineral oil lubricant so the oil in these systems does not require changing during the retrofit process.

Life Cycle Climate Performance

You claim that R-1234yf performance is better than R-744 in terms of LCCP. What is the basis for that claim?

A number of studies have shown the superior LCCP performance of HFO-1234yf over R-744. This included one that was published in a peer-reviewed journal, “Environmental Progress and Sustainable Energy” in 2011 by Stella Papasavva and Stephen O. Anderson. This study used the publicly available Green-Mac-LCCP® calculation tool. It showed a 7 percent improvement for HFO–1234yf in reduced CO2 emissions over R-134a. In contrast, the CO2 emissions were increased by 2 percent with R-744. In addition to this study, detailed presentations by the Japanese Automobile Manufacturers Association (JAMA) and Hyundai/Kia also showed significantly lower CO2 emissions for HFO-1234yf vs. R-744.

What assumptions have been used for the LCCP study, e.g. driving cycle, CoP, Coefficient of Performance or efficiency, fuel consumption, climate conditions?

These studies have followed the Green-Mac-LCCP® model. It´s a model that has been peer-reviewed and accepted as a global standard by more than 50 experts representing 25 companies and other organizations. All the assumptions were clearly defined in the analyses and identified in the publications and presentations and may be found at:

Did these assumptions include the use of the fluid in heat pump mode? If not, why not?

The analyses performed to date have centered on the car cooling application as this is the system in use for almost all vehicles today. There are only a very small number of heat pumps in use today that provide heat as well as cooling. If these systems become more popular, the models would likely be modified to include heating as well as cooling.

Are the assumptions publicly available? Were they peer-reviewed?

Yes, both the model itself as well as the publication noted above has been peer-reviewed.

Has an LCCP been performed for hybrids or electric vehicles?

Currently most LCCP calculations conducted have centered on the most popular vehicle types, either gasoline- or diesel-powered. If and when other vehicle types become more popular, the calculation methods will probably be extended to these as well.


  • Papasavva Study
  • “GREEN-MAC-LCCP: Life-Cycle Climate Performance Metric for Mobile Air Conditioning Technology Choice”, Stella Papasavva and Stephen O. Anderson, Published online 16June 2010 in Wiley Online Library. D01 10.1002/ep.10465. Environmental Progress and Sustainable Energy (Vol. 30, No.2).
  • Green MAC website

Breakdown Products

What is the classification of TFA? Is it toxic?

The stable form of TFA in the environment is the trifluoroacetate ion (CF3COO-). It combines with counter-ions to form neutral salts: with sodium, in seawater, or calcium or ammonium in land. However, “TFA” is used in short for both the acid and its neutral salts. In its 100 percent pure acid form, TFA, like most acids, is a corrosive material. In significant concentrations, not attainable through the decomposition of HFO-1234yf, it can inhibit growth of certain algae species very sensitive to TFA.

Various TFA deposition studies express concern that TFA could reach levels that are dangerous to aquatic life in vernal pools.

Every model of TFA rainout that we are aware of shows that even in vernal pools, there is a safety factor of at least one or more order of magnitude, even in the most liberal scenarios and assuming that all cars are equipped with HFO-1234yf.

Have there been any studies on accumulation in fresh water reserves used for drinking water and the potential impact on humans?

We are not aware of such specific studies. However the factor of safety noted above for vernal pools and the most sensitive algal species (not typically used for drinking water) would indicate to most people that the safety factor for drinking water is much higher.

What is the environmental fate of TFA? Does TFA break down into or react with other substances?

TFA appears to be resistant to biodegradation by the majority of natural or laboratory microbial systems that have been tested. However, laboratory study has shown that certain bacteria, under special conditions, can degrade TFA.

Does TFA contribute to acidification?

The processes of TFA transport or formation make a negligible contribution to acid rain. There is no significant addition to the acids or fluoride already present in the biosphere from natural sources. The pKa value of 100 percent pure TFA is 0.24, making it a much weaker acid than H2SO4 ( pKa=-3.2 ).

Is TFA produced for other uses?

Yes. This compound has been used in the production of pharmaceutical and agricultural chemicals, as well as in many other specialized applications. It is used in peptide synthesis and as a solvent and catalyst in polymerization and condensation reactions, as well as in synthesis of ceramic superconductors.

Are there any other sources of TFA?

The very significant amount of natural TFA in ocean water (over 200 million tons, about 10,000 times more than possible from, say 20,000 tons of HFO-1234yf) , has been attributed to venting from ocean floor fumaroles in scientific literature.

Fluid H was an early candidate molecule under study as a replacement for R-134a. It showed material compatibility issues with certain automotive components as well as stability issues. Consequently it was not considered a viable option as a replacement of R-134a.

Which production facilities are currently available, who operates each of them, and what is the capacity of each?

We do not disclose the capacities of our production facilities and supply agreements. We are currently producing HFO-1234yf in Buffalo, NY and will be receiving material from a plant in China later this year.

How much product have you produced and how much have you shipped to date?

We consider this information confidential.

The automotive industry has carefully considered various options and concluded that R-1234yf is the best overall solution in terms of performance and safety. R-744 (CO2) was part of the SAE Cooperative Research Project and was considered to carry greater safety risks. HFO-1234yf shows no acute effects at concentrations up to 12 percent. This level cannot be reached in the event of a car accident and therefore does not pose any real risk to vehicle occupants. CO2, however, causes dizziness and loss of awareness at concentrations of 2 percent. At 10 percent it may cause loss of consciousness and may result in death.