Natural Refrigerants

I am all for getting back to our roots. So many times nowadays it seems that we over complicate things. The same thing can be said when it comes to refrigerants. If we go back to the infancy of refrigeration and air conditioning we can find natural refrigerants as the primary refrigerant.

Natural refrigerants are just that, natural. They occur naturally within the environment. They are not created in a laboratory like some of the other refrigerant classifications such as Chlorofluorocarbons (CFCs), Hydrochlorofluorocarbons (HCFCs), Hydrofluorocarbons (HFCs), and Hydrofluoroolefins (HFOs). Because natural refrigerants already exist in nature they are very environmentally friendly. None of them have any Ozone Depletion Potential (ODP) and they also have very little Global Warming Potential (GWP).

In today’s world natural refrigerants have begun to make a comeback in various applications due to fluorocarbon refrigerants either being phased out or phased down. Some of the most popular natural refrigerants used today are carbon dioxide, ammonia, and hydrocarbons. (I won’t get into hydrocarbons in this article. If you wish to read our hydrocarbons article click here.)

All of the natural refrigerants can be found in our listing below:

  • Ammonia (R-717
  • Carbon Dioxide (R-744)
  • Hydrocarbons
  • Water (R-718)
  • Air (R-729)
  • Methylamine (R-630)
  • Ethylamine (R-631)
  • Hydrogen (R-702)
  • Helium (R-704)
  • Neon (R-720)
  • Nitrogen (R-728)
  • Oxygen (R-732)
  • Argon (R-740)
  • Nitrous Oxide (R-744A)
  • Sulfur Dioxide (R-764)
  • Krypton (R-784)

Natural refrigerants are used in a variety of applications from large scale industrial operations such as a meat packing plant all the way to a dormitory refrigerator. Ammonia for example is used in storing/processing of food/beverages, supermarket refrigerators/freezers, convenience stores, ice rinks, and much more.

Should you, or your company, consider natural refrigerants? What does the future look like for them? Are they sustainable? In this article we’re going to dive into the pros and cons of these types of refrigerants as well as take a look at their past, present, and future.

Natural Refrigerant Pros & Cons

When considering a refrigerant it is always best to review their pros and cons. As most of you know there is and probably never will be a perfect refrigerant. Each refrigerant you deal with rather it be a synthetic model or a natural one will all come with pros and cons. Take the famous R-12 and R-22 CFC/HCFC refrigerants. They were very efficient and cheap to produce but they damaged the environment greatly with their Ozone depletion.

Natural refrigerants have these sames ebbs and flows only magnified. With R-12 we could all safely say that all CFC refrigerants, including R-12, damaged the Ozone and had to be phased out. Natural refrigerants are a different story as each refrigerant has it’s own specific set of drawbacks.

Before I get into the cons though let’s first take a look at some of the benefits. The biggest and most impactful benefit these refrigerants have to offer is their environmental friendliness. Every natural refrigerant comes with a zero Ozone Depletion Potential (ODP). While ODP isn’t as big of a problem today as it was twenty years ago it is still a point worth considering when reviewing what type of refrigerant you need. The other environmental point are natural refrigerants Global Warming Potential (GWP). For the most part these refrigerants have a very low GWP or a neutral GWP. As an example, carbon dioxide has a GWP of one. (R-22 has a GWP of one-thousand eight-hundred and ten)

Now these next pros that I’m going to mention are refrigerant specific, meaning they do not apply to ALL natural refrigerants. Depending on the natural refrigerant that you choose you could find extremely high efficiency. Ammonia is a great example of this. In many circles ammonia is deemed as the most efficient refrigerant there is. This makes for very low energy costs. This is one of the main reasons larger plants and factories use ammonia as their main source of cooling. Sticking with ammonia, you will also find that ammonia itself is very low in cost when compared to other synthetic refrigerants. This is mainly due to only a small percentage of ammonia supplies are used as a refrigerant. The rest of it ends up going towards fertilizer production. (Source from EPA)


Alright folks so we’ve taken a look at what these natural refrigerants have to offer. They’re friendly to the environment and in some cases they are extremely energy efficient. The question now though is what are the downsides? Well, as I mentioned before each type of natural refrigerant has it’s own specific sets of drawbacks. In this section I’l briefly touch on each of these.

Let’s start firstly with ammonia. It’s widely known as the ‘best’ refrigerant but there is still a lot of hesitation when it comes to using it, especially in a commercial or public area. Ammonia is rated as B2L from ASHRAE. The ‘B’ rating indicates that ammonia is toxic if inhaled. (You can read more about ASHRAE’s refrigerant safety rating in our article on Toxicity and Flammability.) If not handled properly, or if there is an accident, ammonia can be deadly.

Most of the time when a leak does occur it’s captured right away and it doesn’t make headlines. That being said, I do see every few months a report of an ammonia leak at a factory or ice rink and a square block is evacuated by the fire department as a precaution. In one drastic example from 2017 in Canada three fatalities were recorded due to a leak of an ammonia system at a small town’s ice rink. You can read about this sad story by clicking here. While ammonia is dangerous, it doesn’t mean it can’t safely be used. There are more and more innovations each year that makes for safer ammonia use. I’ll get into these further in our next section.

Another one of the most common natural refrigerants out there is carbon dioxide. Just like with ammonia, carbon dioxide dates back all the way to the 1800s and was one of the very first refrigerants. The good news is that carbon dioxide is non toxic and is rated by ASHRAE at a A1. There is no toxicity risk and no flammability risk. The downside though with carbon dioxide is the pressure at which it operates. Carbon dioxide operates at ten times the pressure levels then ammonia or the HFC R-404A. This increased pressure requires systems to be specifically designed to withstand it. That means thicker and more durable components. This leads to more cost of the overall system and also deters some manufacturers from even trying a carbon system. Along with the increased cost there is also higher chance of breakage or part failure due to the increased strain.

The last big con that I wanted to mention mainly focuses on hydrocarbons but the same can be said about ammonia as well. Hydrocarbons are known for their flammability. After all two of the most prominent hydrocarbon refrigerants are propane and isobutane. While the flammability risk does scare away a lot of people from installing these types of systems it should be noted that with a small of charge the risk is shrunk significantly.

I won’t get into every other natural refrigerant option in this section as I could go on forever. Instead, I’ll dive deeper into the more obscure ones when I do a refrigerant fact sheet on each of them. As a brief synopsis though besides toxicity, high pressure, and flammability we also run into problems of corrosion and energy inefficiencies with certain natural refrigerants.

Natural Refrigerants Today & Future

Most of the time when you hear someone talking about natural refrigerants they typically talking about only a few refrigerants. It’s either ammonia (R-717), carbon dioxide (R-744), or hydrocarbons (Propane or Isobutane). While there are some applicable practices of water (R-718) and air (R-729) you normally don’t see these in a standard vapor compression system that we are all used to.

To understand where natural refrigerants today we first need to understand the history of refrigerants. Luckily, history is our next section. The reader’s digest version though is that in the beginning natural refrigerants were the very first refrigerants used. Then, as technology progressed fluorocarbon refrigerants were invented. Since the 1930’s up until present day fluorocarbons have been the dominant refrigerant in the marketplace. Fluorocarbons aren’t perfect though and cause harm to the environment either through Global Warming or through Ozone depletion.

In order to find a more environmentally friendly refrigerant the world has begun to turn back to natural refrigerants. Well, let me put that another way. At this time the industry is at a crossroads. Countries and companies can either move towards the new fluorinated class of refrigerants known as hydrofluoroolefins which has significantly lower GWP then their HFC counterparts, or they can move towards natural refrigerants and hydrocarbons. It’s tough to say who will win the battle between these two refrigerants, or if we’ll end up with a fifty fifty split market.

Even today companies are announcing steps they are taking to be completely HCFC and HFC free. One example of this is Ajinomoto Frozen Foods out of Japan. (Source from This food manufacturer announced that they plan to phase out all of their HCFC and HFC machines by the year 2030 and replace them with natural refrigerant options or other very low GWP options.

In order to make natural refrigerants and hydrocarbons more competitive against their HFO rivals manufacturers have begun looking for ways to reduce the charges required. This is an attempt to make ammonia based systems and hydrocarbon based systems safer for general use and more residential/commercial use. If the charge is small enough that even if a leak does occur the danger is minimal or even non-existent then why wouldn’t you go with a natural based system?

An example of this can be found in some grocery store refrigerator and freezer systems. In our hydrocarbons article we touched on the newer standalone R-290 refrigerators for grocery stores. These stand alone units allow a much smaller charge then a centralized system. But, there are also solutions for centralized systems as well. Newer systems can come with both a primary and a secondary refrigerant. In the main control area ammonia is used and in the display area harmless carbon dioxide is used. This way, if there is an ammonia leak it is isolated to the control room and customers and the general public are unaffected.

Because of these innovations and inventions the world is seeing more and more natural refrigerant applications. This is only expected to rise as older R-22 systems finally begin to retire. Business owners are looking for an alternative refrigerant that will last more then a few years. HFCs are on the way out and it wouldn’t make sense to install a newer HFC system. No, this is why we are seeing more and more ice rinks and other larger plants moving away from R-22, R-134a, and R-404A over to either ammonia or carbon dioxide.

In a completely different sector innovation is still happening with natural refrigerants. This time with carbon dioxide. Daimler, the vehicle manufacturer out of Germany, has developed a carbon dioxide system for their vehicles. This all stemmed back to a battle years ago between Daimler and the rest of the European Union. The EU was pushing to move over to the new HFO 1234yf automotive refrigerant. Daimler resisted, stating that the yf refrigerant was highly flammable. They fought and fought the EU and during this fighting they were also innovating. They now have the first ever automotive carbon dioxide air conditioning system.

As the years go by and technology improves we can only expect the natural refrigerant market to grow and grow and to also move into new and previously undeveloped markets. Aiding in that growth are certain governments and states across the Americas and Europe that are offering business owners incentives and tax breaks for replacing their older HCFC or HFC systems with natural refrigerants rather it be ammonia, carbon dioxide, or hydrocarbons like propane.

Natural Refrigerant History

Alright folks, now for the history lesson. I’ll spare you the read up front if you already read our hydrocarbon page’s history section. It’s going to be about more or less the same as, let’s face it, they have right about the same history.

While the concept of ice harvesting had been around for hundreds of years it was only until the 1800’s when the first real refrigerant systems began to appear. In the 1830’s an inventor known as Jacob Perkins filed a patent. This patent was one of the first vapor compression refrigeration systems in the world. Perkin’s patent had all of the basic parts that we see today: Compressor, condenser, expansion, and the evaporator. In these very early days of experimentation Perkins used the hydrocarbon refrigerant ether. (R-E170) Nearly thirty years later a different patent was taken out by Charles Tellier. This patent built off of Perkin’s vapor compression system but this time Tellier was using methyl ether as a refrigerant.

As the years went by more and more advancements were made in the standard vapor compression system. In the 1860’s a carbon dioxide (R-744) system was designed by Thaddeus Lowe. In the 1870’s an Ammonia based system was invented by David Boyle and improved upon by Carl Von Linde. Shortly before the beginning of the twentieth century another refrigerant was patented over in France known as methyl chloride. (R-40) This new refrigerant was the grandfather to the modern day halocarbon refrigerants that are used across the world.

The 20th Century

In the early twentieth century industrial refrigeration was growing by leaps and bounds across the world. The refrigerant of choice was ammonia. As most of you know, ammonia is seen as the ‘perfect’ refrigerant. It is the most efficient refrigerant out there. The only problem is it’s toxicity. Ammonia is deadly when released in large volumes or in an enclosed area. This is why the industrial application was using it and there was hesitation in the residential and commercial sectors. The commercial sector was growing with limited ammonia systems but not nearly as fast as industrial. The chance of potentially deadly accidents scared off a lot of business and home owners.

At this time most homes still relied on ice boxes and other manual ways to store their food. The homes that did have refrigerators were often quite wealthy. These homeowners used a variety of refrigerants such as ammonia, methyl chloride, sulphur dioxide, and propane. Between all of these refrigerants though the safest and the ones with the least amount of incidents were the hydrocarbons. While Propane and Isobutane are flammable the small charge in each system helped to mitigate the risk. In the 1920’s it seemed that hydrocarbons would be the standard refrigerant for most home and commercial refrigerators.

Hydrocarbons would have been the future except for the lobbying of ice companies and union laborers. These companies lobbied the government about the dangers of hydrocarbon refrigerants and they were successful. Strict safety regulations were implemented on hydrocarbons. An alternative refrigerant had to be used.

Rise of CFCs/HCFCs

In the early 1930’s General Motors and the DuPont Corporation formed a team. This team aimed at one thing: To create a ‘perfect’ refrigerant that could be mass produced, was cheap, safe, efficient, and not flammable. After some time one of the team members, Thomas Midgley Jr., invented the new classification of refrigerants we know today as Chlorofluorocarbons (CFCs) and HydroChloroFluoroCarbons (HCFCs). Two of the most prominent refrigerants to come out of these new refrigerant classifications were R-12 and R-22.

These new refrigerants were revolutionary. No longer could only the rich afford refrigerators and air conditioners. These refrigerants put it within reach of the common man. Shortly after the invention more and more air conditioners and refrigerators were produced. In the 1950’s a better synthesization method was discovered. This improved process caused the market to explode. Demand was everywhere and soon enough there were refrigerators in nearly every home across the country. Air conditioners weren’t far behind either.

This meteoric rise of CFC and HCFC refrigerants caused the usage of hydrocarbons to drop and drop across the world. After all, why would anyone use hydrocarbons if there was a cheaper and safer alternative readily available?

Fall of CFCs/HCFCs

It was in the 1980’s that a problem was discovered. Two American scientists, Mario Molina and Shepwood Rowland, from a California university were the first to notice Chlorine’s effect on the atmosphere. (Remember now folks, all of these CFCs and HCFCs contain Chlorine.)

These two scientists found that when a CFC refrigerant was exposed to ultra-violet irradiation that the Chlorine atom would detach itself from the CFC molecules. The remaining residue is oxidized resulting in the creation of a Chlorine oxidized molecule and a new residue. The Chlorine atom and Chlorine oxidized molecule move their way up to the stratosphere. Within the stratosphere there is a layer called the Ozone layer. This Ozone layer protects the Earth from ultra-violet rays and irradiation. What these scientists found out is that all of this Chlorine from CFC and HCFC refrigerants was working it’s way to the stratosphere. When it reached the stratosphere the Chlorine began to attack and weaken the Ozone layer.

Over decades of using CFCs and HCFC refrigerants Chlorine began to accumulate in the stratosphere and overtime a hole began to form in the Ozone layer. Now, I say hole but this wasn’t a hole per-say. Instead, there was a weakening of strength in the layer. So, while there was not a hole, the thickness of the Ozone was decreasing and decreasing rapidly thanks to the CFC and HCFC refrigerants.

The Ozone prevents harmful UVB wavelengths of ultra-violet light from passing through the Earth’s atmosphere. Without it, or with a weakened version of it, a variety of bad things could happen. Some of these include a much higher increased chance of Skin Cancer, more severe sunburns, more chances of cataracts, and a whole host of other problems.

After discovering the weakening of the Ozone layer nations banded together in what is seen as one of the greatest and most effective treaty’s every made. In 1986-1987 the Montreal Protocol was created and signed by over one-hundred nations across the world. This Protocol was an international treaty designed to protect the Ozone layer and to completely phase out the chemicals responsible for the weakening of the Ozone. The treaty went into effect in 1989.

Soon after that date marked the beginning of the end for CFC and HCFC refrigerants across the globe. The industrialized countries, like America, began to phase out the refrigerants first. R-12 was phased out in the early 1990’s along with all of the rest of the CFC refrigerants. The HCFC refrigerants such as R-22 or even R-502 were given a bit more time. Heck, R-22’s true phase out didn’t even begin until 2010.

Out with the old and in with the new, so they say. The refrigerants that were proposed to replace CFCs and HCFCs were known as HFCs, or Hydroflurocarbons. These refrigerants contained no Chlorine so there was no chance of them hurting the Ozone layer. Some of these refrigerants include popular refrigerants today known as R-134a, R-404A, and R-410A. But, now these HFCs refrigerants are under fire for their increase to Global Warming.


During the transition away from CFC/HCFC refrigerants most countries moved towards HFC refrigerants. Again, HFCs were the easy solution. They were safe, they were cheap, and they didn’t harm the Ozone layer. Although there were some countries and companies that opted towards natural refrigerant and hydrocarbons, the majority of the world switched over to HFCs.

Just like with previous fluorinated refrigerants HFCs were inherently flawed. It wasn’t chlorine this time though folks. With HFCs the big concern was Global Warming Potential, or GWP. Global Warming Potential is a measurement of how much heat a greenhouse gas can trap within the atmosphere. HFC refrigerants are green house gas or super pollutants. The higher the GWP number the more impact the refrigerant has on Global Warming. As a base for the GWP scale we use the natural refrigerant carbon dioxide (R-744). Carbon Dioxide has a GWP value of one whereas the popular HFC R-404A has a GWP of nearly four-thousand.

The use of HFCs across the globe could not continue. This much was certain. What was uncertain though is what would replace HFCs? Would the world go to the natural/hydrocarbon refrigerant route, or would they trend towards a new class of fluorinated refrigerants known as Hydrofluroolefins.

While the world hasn’t phased out HFCs entirely yet, we are well on our way. Europe has already phased out R-134a and are in process of phasing out R-404A and R-410A. California, New York, and other States have announced their plans to phase down HFC refrigerants. This is the only the beginning folks. HFCs will be going away soon.


Natural refrigerants began in the nineteenth century, fluorinated refrigerants had the twentieth century, and natural refrigerants will rise again in the twenty-first century. Unlike CFCs, HCFCs, and even HFCs we can be assured that natural refrigerants will never be going away. They are climate friendly and we will only be moving forward with them as technology advances.

For a business owner or manager looking to replace their aging HCFC or HFC system natural refrigerants are the…. natural choice. (I meant to do that!) On top of being environmentally friendly they also can give you the peace of mind knowing that there is no risk of phase downs or phase outs with natural refrigerants. If there is one thing business owners love is a low risk investment.

Who knows folks, there may come a time where it is only natural refrigerants that are used around the world and our beloved HFCs are a thing of the past.