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Patent data analysis of natural refrigerants, ice image
Landscape / Published, October 21, 2024

Keeping Cool with Low Environmental Impact: Patent Data Analysis of Natural Refrigerants

overview

With global efforts to combat climate change growing and environmental regulations becoming ever stricter, attention is turning to the use of natural refrigerants to replace synthetic refrigerants, such as hydrofluorocarbons. Nicolas Nowak, Senior Consultant in Business Intelligence and Chemistry Team Practice Leader, shares insights into Questel’s patent data analysis of this evolving technical sector, including the perspectives of some of the refrigeration experts that were interviewed as part of the research.

As global temperatures continue to rise, the need for efficient refrigeration systems will undoubtedly increase in the next years and decades. With growing global efforts to combat climate change and stricter environmental regulations, sustainable refrigerants are poised to replace our current reliance on synthetic refrigerants, such as hydrofluorocarbons (HFCs), which have high Global Warming Potential (GWP) due to their greenhouse effects and contribution to ozone depletion. In contrast, natural refrigerants are naturally occurring gases that could replace high-GWP refrigerants, making them key to reducing the ecological footprint of cooling systems.

In part two of this blog, we will share our patent data analysis of natural refrigerants, including filing trends, key players, breakthroughs shaping this field, market coverage, and geographical hotspots. But first, we will explore the technology sector covered by our research.

Part One: What Are Refrigerants?

Refrigerants are chemical substances used in refrigeration and air-conditioning systems. They work by absorbing heat and transferring it in a cycle to achieve cooling of air or objects.

Refrigerants typically have low boiling points, allowing them to evaporate and cool the surrounding environment at relatively low temperatures. When in liquid state, the refrigerant absorbs heat and evaporates into a gas. Then, through compression and condensation processes, the refrigerant releases heat and returns to a liquid state, preparing for the next cycle.

A good refrigerant must combine various special physical and chemical properties to perform well in most systems and environments. Among others, a good refrigerant must have properties such as high evaporative pressure, high critical temperature, low freezing temperature or be a high-density liquid. They must also have special chemical properties such as stability, safety, non-corrosiveness, non-toxicity and, of course, be non-environment degrading.

Image of refrigeration cycle covered by our patent data analysis

What Are Natural Refrigerants?

Natural refrigerants are molecules used as refrigerants that can be found in nature. They were used in the very first refrigeration systems. But, as the technology evolved, they were replaced by man-made, synthetic refrigerants, engineered to overcome some issues such as flammability, toxicity, and corrosion. The most used natural refrigerants are ammonia (NH3 – R717), carbon dioxide (CO2 – R744) and hydrocarbons (such as propane R290 or isobutane R600a). Alternatives such as water (H2O, R718) and air (R729) also fall under the category of natural refrigerants. 

What is GWP?

The global warming potential (GWP) is a value that indicates the contribution to global warming. The GWP refers to the value of CO2 as a benchmark with a GWP value of 1. This means that a gas such as R404A, with its GWP of 3922, contributes 3,922 times more to global warming than the same amount of CO2. Natural refrigerants have a GWP of 0 to 5.5. 

Despite their drawbacks, natural refrigerants have great advantages that are fast-becoming a priority:

  • (i) they are climate-neutral: they make no or only a small contribution to global warming, and
  • (ii) they are cost-effective: they are inexpensive to produce, have long-term availability and enable efficient operation of refrigeration and air-conditioning systems.
     

Some critics claim that systems with natural refrigerants are more complex to build, which might be true in particular for CO2, which needs a higher system pressure. However, if a holistic view is taken, considering all system costs, from installation and operation through to disposal, it is easy to conclude that refrigeration systems with natural refrigerants have the lowest lifetime costs.

Refrigerants Nomenclature

To avoid refrigeration engineers having to remember chemical names and to avoid mistakes in identifying refrigerants, a simple naming and numbering system is used thanks to international standards. Hence, refrigerants are represented by the letter R (as in refrigerants) followed by a two- to four-digit number and, in some cases, one or two letters. The general designation Rxyz is determined by the chemical composition of the molecule, in which “x” designates the type of molecule (short alkane, (a)zeotrope, inorganic compound, etc.) and “y and “z” give more information about the molecule itself. More information is available here.

Why Are Natural Refrigerants Making a Comeback?

A few decades after use of the first synthetic refrigerants—Chlorofluorocarbons (CFCs) and Hydrochlorofluorocarbons (HCFCs)—they were discovered to have had a disastrous impact on the ozone layer. Under the Montreal Protocol, adopted in 1987, several countries agreed to first phase out CFCs and HCFCs. However, their potential replacements (HFCs) were later found to contribute heavily towards global warming. Subsequently, under the Kigali Amendment of the Montreal Protocol, countries committed to a gradual phase down of HFCs, with the aim of an 80-85% reduction by the late 2040s.

Today, CFCs and HCFCs are banned in Europe, with HFCs being controlled by the F-Gas Regulation. These regulations aim to cut fluorinated gas emissions by two-thirds before 2030 compared to 2014 levels, under a phased approach, starting with the most environmentally harmful according to GWP. The goal is to drive out high-GWP HFC refrigerants and replace them with low GWP refrigerants or refrigerant blends.

After the HFCs, came the Hydrofluoroolefins (HFO), that could perform as well as previous refrigerants, but have a very low GWP (around 1 for the best ones), and no ozone-depleting property. That solution seemed ideal for a while, but in 2021, a revision of the PFAS definition by the Organisation for Economic Co-operation and Development (OECD) found that various HFOs used today as low-GWP refrigerants would be considered PFAS. HFOs in themselves are safe, but their atmospheric decomposition products, like other plastic materials such as PTFE and Teflon®, are now falling under the OECD definition. Some estimate that more than 12,000 substances would be classified as PFAS.

Understanding PFAS

Per- and polyfluoroalkyl substances (PFAS) are a large, complex group of synthetic chemicals that have been used in consumer products around the world since about the 1950s. They are ingredients in various everyday products. PFAS compounds originate from man-made chemicals that are resistant to degradation because of the presence of the strong carbon-fluorine bonds in their chemical structure. There are sometimes considered to be “Forever chemicals”, as able to accumulate almost indefinitely in water and air streams. See this comprehensive study.

Following this development, reports such as The Rising Threat of HFOs and TFA to Health and the Environment have examined the evidence that R1234yf, the most widely used HFO as a refrigerant, by itself and in blends, represents a growing threat to human health and the environment via its atmospheric degradation product, trifluoroacetic acid (TFA). The largest use of R1234yf has been as a replacement for R134a (GWP of 1,430) in mobile air conditioning. Moreover, many HFO blends which include R1234yf as a key ingredient, are used in thousands of stores globally as well as in industrial facilities, ice rinks, and other applications.

Hence, year after year, all potential replacements for natural refrigerants have been deemed unsuitable for environmental reasons, paving the way for natural refrigerants to come back and play a key role in tomorrow’s refrigeration needs. However, as mentioned earlier, these refrigerants are not perfect, and some considerations need to be kept in mind before their worldwide adoption. 

Potential Drawbacks to Natural Refrigerants

Each of the three main candidates of natural refrigerants have a key drawback that systems built for them must avoid:  

  • Propane, like other hydrocarbons, is highly flammable, requiring robust safety protocols and system designs to mitigate fire and explosion risks.
  • Ammonia is toxic so it requires careful handling.
  • Carbon dioxide operates at much higher pressures compared to traditional refrigerants, which can stress system components and increase the risk of leaks or ruptures. 

As is the case for all chemicals used at home or in industries, various considerations should be in kept in mind; namely, the need to:

  • Provide proper training to ensure that technicians are capable of handling natural refrigerants safely and effectively;
  • Develop the necessary infrastructure for the widespread adoption of natural refrigerants, such as availability of parts and equipment designed for these refrigerants; and
  • Consider their overall environmental impact, including energy use and potential indirect emissions, throughout their lifecycle, from production to disposal.

As Dr Michael Kauffeld, Professor of Refrigeration, Air Conditioning, and Heat Pump Technology at Karlsruhe University of Applied Sciences, commented during the interviews we conducted for our research, there will certainly be: “different natural refrigerants for different applications, as we need to look at the vapor pressure curve, the flammability, toxicity, volatility, availability of these gases, etc.” With location possibly also playing a role, there might not be a winner-takes-all gas, but a multitude of acceptable solutions.

This corroborates the very specific use of propylene by ECOOLTEC, a developer of new generation transport refrigeration machines. As Jürgen Süß, previously Chief Technology Officer (CTO) of ECOOLTEC shared with us, the “cooling generation [of this specific technology] uses hydrocarbons, more specifically propylene, which gives 10-12% more cooling capacity than propane.”

Part Two: What Patent Data Reveals About the Technological Field

Patent data analysis offers valuable insight into innovation, including helping us to predict the future of a technology. In this part, we profile what patent filings for low-GWP refrigerants, including natural refrigerants, HFOs, and other low-GWP HFCs, can tell us about the future of these gases, including the major industry players and main R&D and market sectors. Our patent search focused on any low-GWP gases and on cooling or air-conditioning systems that use them.

Patent Data Analysis of Natural Refrigerants

To understand the innovation and R&D activities in this technology, we performed a macro search using our proprietary IP intelligence software. By analyzing the patents collected using our IP consulting services expertise, we were able to create a fascinating global insight into innovations and investment in this field.

What Do Patent Dynamics Tell Us About the Status of this Field?

In total, the database comprises over 2,000 patents families filled in the last 20 years. Patent filing dynamics reveal a field that did not see much innovation in the first 10 years, then experienced a high activity increase from 2016 to 2019, with a compound annual growth rate (CAGR) above 20%. 

Most likely, this increase is related to regulations that occurred first in 2014 with the EU F-Gas Regulation Revision (No 517/2014), which imposed strict measures for the use of HFCs and other fluorinated gases, including phase-down targets for HFCs and complete bans on certain high-GWP refrigerants. In addition, 2016 saw the Kigali Amendment referenced earlier: a global agreement to phase down HFCs, starting first within developed countries in 2019.

However, the increase in fillings was not sustained for long, with the global economic slowdown caused by COVID-19 starting in 2020 potentially shifting priorities slightly in those years. In 2022, the dynamic appears to be picking up again, with a high number of fillings already registered for 2023. 

Chart showing patent dynamics from our data analysis of natural refrigerants

An important characteristic of this database is the relatively high number of litigations and oppositions, which is 2.5 times higher than typical database of this size and age. Mainly, these oppositions and litigations occur around patents about synthetic low-GWP gases and involve the biggest names in the field. Indeed, around two thirds of these legal proceedings involve only three companies, namely Honeywell, Chemours, and Arkema. 

Geographical Hotspots for Low-GWP Refrigerants

Priority country filling most often occurs in the country in which the R&D is undertaken, so looking at this data shows us which countries are the most innovative and which are the ones that seek to protect their inventions. As is often the case, China is the main innovative country with more than a third of fillings.

As is also often the case, Europe is better represented in protection countries than in priority regions, as Europe is not only an important global market but also often a pioneer in regulating and adopting solutions for environmental protection and combating climate change. In fact, according to Alexander C. Pachai, recently retired after, among others, over 20 years at Johnson Controls: “In terms of sustainable regulations and in particular in the refrigeration space, China is following very closely what is happening in Europe.” This could lead to leaps in the right direction for this huge market and the future of the whole field.

Geographical hotspots revealed by our patent data analysis of natural refrigerants

Low-GWP Refrigerants: Patent Dynamics and Top Players

The graph below shows the top 13 fillings assignees in our database. Most top actors are big companies in refrigeration systems manufacturing, such as Daikin, Gree Electric Appliances, Panasonic, Mitsubishi, Carrier, etc. and/or refrigeration gases producers (Honeywell, Chemours, Mexichem, Arkema).

Recent activity varies greatly. Some companies have filled fewer than 30% of their patents since 2017 (Sanden, Mexichem, Denso, Carrier), while some others have filled most of their portfolio (>70%) in the same timeframe (Daikin, Chemours, Panasonic, Idemitsu, etc.), seemingly positioning themselves for the transition to come in the field.

Key players revealed by our patent data analysis of natural refrigerants

We also noticed that the main actors cite themselves very strongly when compared to other databases of the same size and age. This corroborates the fact that the domain is very competitive and that the players monitor each other closely, as seen with the high number of disputes and oppositions.

As expected, the major gas players, Chemours and Honeywell, are cited the most and have the most litigated patents. Daikin cites these players frequently, because its devices and systems will be able to operate with their gases. Indeed, most Daikin patents mention all kinds of low-GWP refrigerants, albeit not necessarily natural ones.

Hence, we saw here that the market for low-GWP gases and systems is very competitive and set to grow, thanks to the global increase in demand of cooling and air-conditioning systems. 

Which Gases Are Set to Take Over?

In our database, CO2 is the gas mentioned by most patents (30% of the database), and also the one that has seen the biggest increase in patent filling in the last 10 years. Propane is the second most used gas in our database, but with less than half the number of patents of CO2. 

Emerging technologies revealed by our data analysis of natural refrigerants, chart

In addition, CO2 is by far the most independently discussed refrigerant, with more than two thirds of the patents mentioning it as a potential gas for a cooling system, only mentioning CO2 and no other refrigerant, suggesting that the systems are specifically designed for it. This can be linked to its properties, given that it necessitates special systems and pressure handling to accommodate its physical properties.

However, these results do not go against the adoption of CO2 as a very effective and mainstream refrigerant, according to Kenneth Bank Madsen, CTO of ADVANSOR, a designer and manufacturer of CO2 systems for commercial and industrial cooling and heating, who says that “CO2 is used more and more in industrial systems because of the low temperatures needs; furthermore, CO2 can do almost all applications despite higher pressure needs.”

Propane is also highly discussed in our database, but with around half the patents as CO2.  In addition, it is often mentioned in conjunction with other gases, as it can easily be used in existing systems or replaced by other hydrocarbons. In the battle for mobile air-conditioning and electric vehicle (EV) battery cooling in particular, propane could be at the forefront; indeed, Carloandrea Malvicino, CO2 Emission Reduction Strategies Director of STELLANTIS is persuaded “propane is the best for EVs”, mentioning that “CO2 is not so effective in very hot summer conditions, so it can't be a worldwide solution for car manufacturers” and that “propane is cheap, and only 200-250g is needed in a car”. He discards the flammability issue, also pointing out that we put 50 liters of gasoline is our cars without a second thought today.

Concerning synthetic gases (HFOs and HFCs), a slight decrease in fillings is perceivable since 2019, maybe reflecting a shift towards more natural refrigerants. The next few years will be interesting to monitor as patent filings react to market news.

Looking Forward

According to projections by the International Energy Agency (IEA), the demand for air conditioning and cooling is expected to increase by 4.5 times for non-OECD nations and by 1.3 times for OECD countries between 2010 and 2050. Thanks to legislation and commitments made on a regional, national, and worldwide level, there is a significant market for new refrigerants and related systems. 

It is anticipated that a trend away from conventional fluorinated refrigerants and toward sustainable substitutes—particularly natural refrigerants such as ammonia, carbon dioxide, and hydrocarbons—will continue and even accelerate. Indeed, their favorable environmental effects, due to their lower system charges, combined with GWP values approaching zero, make their direct impact on global warming negligible.

After our interviews with refrigeration experts, we drew three main conclusions: 

  • There is no technical barrier to the adoption of natural refrigerants, everything exists and is functional. The only existing barriers could be:  
    • Training/education and adapting the standards,
    • Lobbying of top actors (especially chemical companies with patents protecting synthetic refrigerant compositions),
    • Availability of compounds (in Africa for example).
  • CO2 and propane are very versatile. They are widely used and have a very wide range of applications, from small refrigeration to industrial installations.
  • There are many projects reflecting proof of concept, with all cited examples already implemented and working perfectly and featuring all types of refrigerants (CO2, propane, propene, ammonia, water, etc.)

For example, Jürgen Süß mentioned that the “best efficiency of F-gases are always beatable by natural refrigerants,” and that “we don't need F-gases anymore.”

Indeed, policies such as the F-Gas Regulation promote the gradual phase-out and decrease of high-GWP refrigerants, encouraging the use of more environmentally friendly substitutes. Industry will need to find ways to adapt to this paradigm shift. If the EU decides to adopt a universal restriction of F-Gases, then it could take anywhere from 5 to 15 years to implement replacements, depending on whether refrigerants receive a deferral. However, deferrals are only likely for applications where there are no commercial alternatives and/or alternatives need time to scale production—and natural refrigerants are seemingly viable alternatives already. Their adoption is expected to rise across sectors such as industrial cooling, commercial refrigeration, and domestic appliances, as businesses and consumers seek greener options for temperature control.

Patent dynamics, along with market research and expert interviews, can provide valuable insights into research and innovation trends and markets, as we hope this patent data analysis of low-GWP and natural refrigerants illustrates. For further insights into patent activity in this or any other technical sector or for specific advice or support, contact the Questel IP Consulting team. 

Follow our publications and webinars in our Resource Hub and Webinars & Events section for future insights. 

Nicolas Nowak is a Senior Consultant in IP strategy and innovation and the Chemistry team Practice Leader. Holding a Master’s degree in Analytical Chemistry and Quality Management, and a PhD in materials chemistry, Nicolas has more than 16 years of experience in inorganic chemistry research, project management and consulting activities.