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My sandwich offering; how to calculate the GWP for refrigerant blends
This week in the northern hemisphere is a tough week. Most folks are back at work. It’s still cold and dark. Blue Monday and all that. I thought I might be immune, but perhaps not as much as I thought...
Add to that, one day this week I had separate calls with good people in the US, Europe and SE Asia. The conversations covered everything from climate policy, carbon credits, refrigerant leak mitigation and digital twins.
And therein lies part of my challenge. The f-gas topic reaches so far and wide, it is not always easy to settle on a point to write about here.
I happened to also be sitting (virtually) with some writing colleagues during the week, and this same topic came up. Sometimes you just don’t know what to publish; in which case you go back to your basic sandwich instructions (thanks). Take something that is now straight forward to you, and write about that…
So what would be of use to my readers out there? I can give you tips on growing tomatoes (hint: rabbit manure), configuring routers or changing a clutch. But as most of you are here to get insights on refrigerants and f-gases I’ll stay on track.
Today’s sandwich is calculating GWP emission values from refrigerant blends.
Many folks when they first come across refrigerants may not be aware of just how many are out there. They might think there are a handful, but these days there are hundreds, depending on what you include. There’s such a quantity, largely because of refrigerant blends.
In simpler times, the common refrigerants were a single gas, such as the original R12 (Freon™️), R22 or R134a. Manufacturers started blending different gases together to mitigate some of the unwanted aspects and to enhance performance properties for different applications.
You may recall from my recent newsletter on heat pumps I referred to the HFC refrigerant R410a. It is a very common refrigerant, often found in domestic units, and a 50/50 blend of the single HFC refrigerants R32 and R125. Tip here; the refrigerants series that start with a 4 or 5 are blends (e.g. R407c or R513a).
By now you’re aware that most HFC refrigerants have high global warming potentials (expressed as CO2e – carbon dioxide equivalent). If you dig around the internet for GWP values however, you will likely come across different numbers. For R410a you might find CO2e figures of 2088, 1920 and 2256.
Cue some head scratching.
This is often because the values refer to different IPCC reports. Part of ongoing research and studies, and an improved understanding of how these gases trap heat in the atmosphere. You can find an example of some of that research here.
Getting back to the sandwich. To calculate the GWP of a blended refrigerant we simply sum the individual GWPs of the component gases, based on their blend proportion. What’s called a mass fraction calculation.
Let’s look at an example for the blend R410a.
We can start by using the latest GWP figures from the most recent IPCC Assessment Report (AR6) released last year. Recalling that R410a is a blend of two other refrigerants – R32 with a GWP of 771 and R125 with GWP of 3740.
As the blend is 50/50 => (771 *0.5) + (3740 *0.5) = 2255.5
2256 is the GWP for R410a based on the most recent data.
However, if we want to use the IPCC Assessment Report 4 (AR4) data from 2007 (yes many folks still use these older figures). The GWP for R32 and R125 are 675 and 3500 respectively.
If we work that one; (675 * 0.5) + (3,500 * 0.5) = 2087.5
We get 2088 which is the value based on older AR4 figures.
Note also these are the 100 year GWP values to allow comparison with CO2 . There are some good arguments for using 20 year values but that’s a topic for another day.
You might be thinking also. If I’m building a company emissions inventory perhaps it is in my interest to use the lowest figures 🤔. Hence if you are scrutinising reports best keep an eye out. For accuracy the latest figures should ideally be used, inline with the Paris Agreement reporting rulebook.
As company reporting is largely voluntary, I’m aware many decide themselves what to use. That’s besides whether they include refrigerant or f-gas emissions at all.
You might also be asking; how do I determine the blend ratios (they are not all 50/50 btw)? You can find some of them here. Or if you want a short-cut for the blend calculations or the 20 yr values just ask and I’ll happily email them to you. You can reply to the newsletter email (yes it works) or via the website contact form.
Where the F-Gas hides
Each week I provide an example of where f-gases are utilised, or used to produce something. They are present in more things than most people realise…
Recently I managed to catch the excellent ‘Sur Le Front’ on French television. The program does a great job of shining a light on various environmental issues around the world. This particular edition was on ‘fast fashion’, and investigated what happens to our unwanted clothes. Just like a lot of refrigerant containing equipment (fridges and AC units), it gets dumped in Africa. In particular, Ghana. A place I’ve done some work before with some great people, and it seems to be on the wrong end of a lot of it.
Aside to the refrigerant connection, there is another relationship between clothes and fluorinated gases. Many textiles are coated in it.
When you see something labelled ‘quick dry’, or something water repellent, stain resistant or proper hard-core waterproof, chances are it has a fluorinated coating. Just like the shower screen from last week’s newsletter…
In the past, the textile industry used the toxic and now restricted PFOS and PFOA. But things have since moved on to other formulations, and many of these formulations are still fluorinated.
The industry marketing telling us they are more ‘environmentally friendly’, however we still have this problem where these coatings are manufactured using the HCFC-22 (R22) f-gas as feedstock. See my broken record bit about the problems associated.
Or looking at it another way.
If you’d like to dive further into how the coatings are applied and how some of the fluorinated GHG emissions come about, there is a good paper here from one of the IPCC contributors. It uses the word ‘urgency’ in the title.
Some clothing manufacturers, to their credit, are trying to move away from fluorinated textile treatments. Patagonia for instance, has been very open about the challenge. They are tackling it seriously and you can read more here.
There is loads more to explore around chemical use in clothing and footwear of course. It is mind boggling what goes into football boots (yes you’ll find fluorinated chemicals) and just wait till you find out how they do wrinkle-free…
Right, that’s all for this week and ‘till next time.
p.s. last week’s title track – The world has turned and left me – was courtesy of Weezer (not Deezer :)
Fixed stuff here for newcomers
There is lots of news every week from the cooling industry and plenty of newsletters that cover it well. The intention is to keep this newsletter focused on the most prominent f-gases (fluorinated greenhouse gases), the most common of which are refrigerants and importantly their environmental impact. That’s the lane I’ve chosen - I’ll do my best to stick to it.
Below is the seven (formal) greenhouse gases that countries and companies should track, report and hopefully reduce.
Carbon Dioxide (CO2)
Nitrous Oxide (N2O)
Sulphur Hexafluoride (SF6)
Nitrogen trifluoride (NF3)
There is also the still circulating, ozone damaging chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and the ‘new-generation’ hydrofluoroolefins (HFOs).
Hopefully you can spot the pattern.
Emissions from f-gases and refrigerants have been the fastest growing greenhouse gases over the past decade (more than CO2 and methane - check out IPCC WG3 summary for policy makers). They are also classed as super pollutants given their outsized global warming and other environmental impacts.
Some useful permalinks
The scale of the climate challenge can often feel daunting. This piece helps me take a step back and understand where we need to focus first - recommend a read.
There are plenty of technology solutions available to address the cooling and refrigerant challenge. You can find many of them here
Beware when the same entities who have contributed to the current f-gas problem propose you new solutions… This is a good place to get up to speed.