The concept of refrigeration and air conditioning has been around for over one-hundred and fifty years. In the infancy of this industry there were a specific set of refrigerants used. These refrigerants were known as ‘natural refrigerants.’ Some of these natural refrigerants included some of the basic elements found today such as water, air, and carbon dioxide.
Within the category of natural refrigerants exists a subcategory known as ‘hydrocarbon refrigerants.’ Hydrocarbons are one of the most basic elements found on Earth. They consist entirely of hydrogen and carbon. In the refrigeration and air conditioning world hydrocarbons can be used as refrigerants. Some of the most commonly used hydrocarbon refrigerants are Propane (R-290), Isobutane (R-600a), and Propylene (R-1270).
A full listing of hydrocarbon refrigerants can be found in our listing below:
- Propane (R-290)
- Isobutane (R-600a)
- Butane (R-600)
- Ethane (R-170)
- Dimethyl Ether (R-E170)
- Methane (R-50)
- Pentane (R-601)
- Isopentane (R-601a)
- R-136A (Mixture of Propane & Isobutane)
- R-436B (Mixture of Propane & Isobutane)
- R-441A (Mixture of Ethane, Propane, Isobutane, and Butane)
- R-510A (Mixture of Dimethyl Ether and Isobutane)
Today hydrocarbons are used across the world in vending machines, supermarket refrigerators/freezers, commercial refrigeration, food processing, cold storage, industrial refrigeration, refrigerated transport, chillers, air conditioning systems, and heat pumps. As you can see, they are highly adaptable to various applications.
Along with versatility hydrocarbon refrigerants are famous for their environmental friendliness. Other refrigerant classifications such as CFCs, HCFCs, and HFCs all have significant environmental drawbacks. For example, CFC and HCFC refrigerants contain chlorine which was found to be damaging the Ozone layer. These refrigerants were phased out due to their high Ozone Depletion Potential. (ODP)
While HFC refrigerants do not harm the Ozone layer they have another environmental downside known as Global Warming Potential. (GWP) HFC refrigerants are Greenhouse Gases or super pollutants. The higher the GWP number the more damage the refrigerant does in Global Warming. As I write this article HFCs are still commonly used throughout the globe but we are slowly beginning to see them phased down as well.
With HFCs, CFCs, and HCFCs all soon to be gone there are only two main choices left. The world can steer towards the new classification of refrigerants known as HFOs or the world can go back towards it’s roots with natural refrigerants such as hydrocarbons.
Hydrocarbon Refrigerant Pros & Cons
Hydrocarbon refrigerants have zero Ozone Depletion Potential and have a very low Global Warming Potential. The absolute highest GWP on hydrocarbon refrigerants that I could find was twenty-five. The other hydrocarbons were all between five and zero. As a point of comparison, let’s look at the commonly used HFC R-404A refrigerant. 404A’s GWP is three-thousand nine-hundred and twenty-two.
That number is astonishing and it clearly illustrates the picture as to why many companies are looking towards hydrocarbons for their future refrigerant and air conditioning needs. These companies receive the peace of mind that the refrigerants they are using are never going to be phased down or out. On top of that, hydrocarbons operate at nearly the same temperatures as HFC refrigerants do but on a smaller refrigerant charge then standard HFC systems. Depending on the application you need you may find that the price point is similar to that of HFC systems as well. (If you get into larger charged systems the price will go up significantly due to the shielding required.)
Hydrocarbons aren’t all a bed of roses though folks. There are no perfect refrigerants out there today and I’m doubtful there ever will be. There is always going to be a downside to whatever refrigerant that you pick. It could be cost, efficiency, operating pressure, toxicity, or flammability.
In the case of hydrocarbons the downside is their safety and flammability ratings. Unfortunately, here in the United States the concept of flammable refrigerants scares a lot of contractors off. However, in recent years hydrocarbons have begun to gain in popularity throughout the country. You can find them in most new vending machines and other smaller applications.
Hydrocarbon Refrigerant Safety
In this section we’re going to take a look at the most prominent con when it comes to hydrocarbons, flammability. Just like with anything that is dangerous, if the proper precautions and care are taken then the risk is minimal. Hydrocarbon refrigerants are no different. Yes, they are extremely flammable when compared to other commonly used refrigerants like HFCs and HFOs. But, again, if the proper care is taken then you will be fine.
In an effort to ensure the safety of all users of hydrocarbons there are safety regulations that are monitored and controlled by various agencies. Some of these organizations are local, national, and even global. Today, the standards for using hydrocarbon refrigerants can be found under the following statutes: IEC 60335-2-40, IEC 60335-2-89, ISO 5149, and EN378. (Source from Danfoss.com)
The main risk of hydrocarbons is ignition or explosion of the refrigerant. This can occur when the hydrocarbon is between what’s known as the lower and upper flammability limits. (LFL and UFL.) If the proper safety standards are followed then you should not encounter the scenario where the refrigerant exceeds the lower flammability limit. Please note that the type of safety standards and procedures can change depending on the charge size that you are dealing with. Obviously, the larger the charge the higher the risk.
Flammability problems can also occur if you are attempting to retrofit an existing fluorocarbon system over to a hydrocarbon refrigerant. (Please note, that retrofitting an HFC system over to hydrocarbons is illegal in the United States.) Fluorocarbon systems are NOT meant to handle flammable refrigerants and you will need to ensure the proper precautions are taken in the event of a retrofit. Another point of note when retrofitting a fluorocarbon system is to ALWAYS change the label on the system. There are documented cases of technicians smoking while working on an air conditioner that was retrofitted over to propane. The unit was not relabeled and an explosion occurred. Unfortunately, this incident led to the deaths of two technicians. You can read more about this story by clicking here.
As we mentioned above, flammability is the main risk when working with hydrocarbon refrigerants. While hydrocarbons are not necessarily toxic like Ammonia it can still have detrimental effects if the concentration is high enough. In extreme cases asphyxiation can occur. It is very important that only authorized and trained personnel work on hydrocarbon refrigeration and air conditioning systems.
Hydrocarbon Refrigerant History
Ok folks, so now that we know what hydrocarbon refrigerants are let’s take a look at some of their history, how they came to be, and what the future holds for them.
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.
As I mentioned above, the next question is will the world pivot towards HFOs or towards natural refrigerants like hydrocarbons? At this time it’s difficult to say. If I was to make an educated guess I would say that we’re looking at about half and half. Some companies and countries are pushing entirely towards the new HFO refrigerants or even to lower GWP HFC refrigerants such as R-32. Other areas have begun developing new technologies to allow for easier use of natural refrigerants such as Carbon Dioxide.
When it comes to hydrocarbons we can find their usage scattered around the globe in various applications. Due to the flammability risk we find most hydrocarbons are in systems that require smaller charges. Obviously, the smaller the charge the less the risk. This is why that in Europe hydrocarbons are the dominant refrigerant for refrigerators. There are over fifty million refrigerators using isobutane (R-600a) across the European continent. Even with all of these refrigerators there are no reported accidents with these ‘flammable’ systems. (If you know otherwise, please reach out to me.)
Going right along with the smaller charged systems like refrigerators we can also find hydrocarbons in vending machines and ice machines. This initial push of using propane and isobutane in vending machines began with our eastern neighbors Japan and Korea. In recent years we are now beginning to see hydrocarbon vending machines being produced and distributed throughout the United States.
Another market that hydrocarbons have their sights on is the supermarket and convenience store refrigerators and freezers. With the current HFC systems that we use today they are all connected and managed through a control room. In order to keep all of these units cool and working a rather large refrigerant charge is needed. Hydrocarbons provide an alternative solution. A hydrocarbon unit will come standalone. It is not connected to a main control room. In fact, it’s plug and play. You can move it to wherever you need within the store and then plug it in. Super market managers love this feature as it makes that much easier to display their sale items to their customers. Along with the ease of use, managers will also notice an efficiency savings by switching to hydrocarbons.
The big selling point though by having their units as a stand alone system is the much smaller charge. Just like with refrigerators and vending machines, the lesser the charge the lesser the risk. Hydrocarbons just wouldn’t be feasible to use in a HFC super market system. The charge would be too large.
These hydrocarbon systems are gaining more and more popularity in supermarkets across the US, Europe, and Japan. The Whole Foods chain has over one-hundred stores using hydrocarbons, Target more then nine-hundred stores, and Aldi over two-hundred stores. On top of these grocery chains we have also seen a rise of gas stations switching to hydrocarbons.
While smaller air conditioners seems to be the logical next step the United States’ Environmental Protection Agency has not deemed hydrocarbons acceptable in air conditioner use.
The good news is that in recent years the EPA has begun to relax some of their charge restrictions on hydrocarbons when it comes to refrigerators and freezers. A SNAP rule was issued by the EPA on their changes back in 2018 and can be found by clicking here.
For most of the twentieth century the outlook for hydrocarbon refrigerants was grim. They had been eclipsed by CFCs and HCFCs in the early 30’s and then eclipsed again with the rise of HFCs. However, it seems that in the twenty-first century the world will fall back in love with hydrocarbons.
The hydrocarbon market is growing by leaps and bounds and with each year that passes the possible market expands. Regulations and restrictions are being relaxed to allow hydrocarbons to pave a path to a bright and cleaner future. Chances are if you haven’t run across a hydrocarbon system yet you will very soon.
Thanks for reading,