I've heard that AC is responsible for the hole in the ozone layer

 

 
 

 

Whilst not entirely true there is an element of truth in this story. Up until about thirty years ago only luxury cars had AC in Britain; some Mercedes, BMW's, Jaguars, and the top models of the popular makes, such as the Ford Granada/Scorpio and the Vauxhall Senators. Rolls Royce had a nice system and performance cars that would otherwise be extremely hot and uncomfortable such as Ferrari, Lamborghini and Porsche had to have AC. Not only cars of course, well over thirty years ago on the top-of-the-range Volvo lorries air conditioning was a standard fitment - it was not even an option. Many farm tractors and most combine-harvesters were also so fitted. They used a system much the same as today but the difference was they used a refrigerant popularly known as Freon.

Freon is a trade name but is properly called R12 and it is this refrigerant, which is a CFC, and the mis-use of it by the refrigeration and AC technicians of the day that is partly responsible for the problems in the ionosphere. This refrigerant (invented around 1932) was not only used in AC of course, every domestic refrigerator and freezer all over the world was filled with R12 as was every shop frig or freezer and also the walk-in chillers that butchers have and the huge cold stores that farmers use and the vast freezer warehouses that the processors and the supermarkets use. Food safety legislation over recent decades has forced the use of refrigeration into many areas of shops where they previously used just the display counters, one has only to notice the large number of chill cabinets in shops for cakes and sandwiches and cheese and milk and drinks and - the list is endless. Additionally there is now a large number of refrigerated lorries on the road where chilled or frozen food must by law be kept to set temperatures during delivery: take a look when you are next driving on a motorway and first look at the number of Tesco/Asda/Morrison/Sainsbury/etc lorries you see - almost every one is a reefer (refrig), then look at the number of similar artics used by the supplier companies, I'm sure you will be amazed at the extent of refrigeration in transport. Almost every application where refrigeration was needed you would find R12 or another similar refrigerant of the same family of CFC's, the use of it world-wide was huge. Every frig we the general public scrapped would have been broken up by the rag-and-bone man to recover the steel and copper and the R12 allowed to escape.

Refrigeration is not the only source of this CFC though. Because it was thought to be almost completely safe and because it is not flammable it was ideal as a propellant in aerosol cans (the pressure that makes them spray). Think how many hair spray, furniture polish, fly spray and touch-up paint spray cans were used, especially with the bouffant hairstyles of the sixties. These days the propellant used is not a CFC but is usually extremely flammable so don't smoke when you spray your hair.


Hindsight is a wonderful thing and if we were able to put the clock back I'm sure that things would have been done differently, but, up until the mid '80s the best knowledge available said that the release of R12 into the atmosphere was safe. In those days, if there was a problem in the system, the refrigerant was released as not only was it thought to be safe to do so, it was relatively cheap and therefore the customer would benefit from a completely new charge of refrigerant with no possible contamination. One cannot blame the local Sainsburys for what was done on their behalf by the technicians of the day; with the knowledge available then they were doing what was thought right at the time. Now that we know that over a long period of time CFC’s break down and eventually damage the ionosphere, most refrigeration is handled by a different family of gasses, thought to be safer! When a refrigeration or an AC system develops a fault the refrigerant is recovered and recycled - we have moved on.

I think it would be safe to say that by late 2013 there are very few cars in the UK that still have a working pressure of R12 in the AC system. We do find the occasional example but they are becoming very rare. Most of the pre-1993 cars would have been recharged since 2001 and would now have a replacement refrigerant in them or would have been converted to R134a. R12 may not be completely dead and buried however - although no longer used in car AC systems it was widely used by Medicine and also by the Military (among other things it was used to cool the warhead in missiles I believe) but I really don't know if that is still true in 2014.

Whilst there is no change in the theory that CFC's are mostly responsible for the hole in the ozone layer, research in 2007 at NASA's Jet Propulsion Laboratory in Pasadena is showing that the breakdown of the chlorine molecule (dichlorine peroxide) was extremely low in the wavelengths available in the stratosphere and as such, atmospheric scientists are saying that they now don't quite understand how ozone holes came into being. Nevertheless, at the moment, CFC's are still the main suspect for the problem.

The latest development in "saving the planet" means that a new generation of refrigerants are coming to vehicle air conditioning. I am not going to bore you with the science (I am not sure that I entirely understand it myself) but the theory is that the Global Warming Potential (GWP) of R134a could do more damage to the environment that those with a lower GWP. The new refrigerant chosen is effectively a mixture of gasses which closely mimic the performance of R134a but have a much lower GWP. This refrigerant is called HFO1234yf or R1234yf. Although delayed by two years the first cars with this new refrigerant have arrived during 2013 and by 2017 all new cars should contain this R1234yf. There is no intention at present to completely ban the existing refrigerant as was done with R12 so only these new cars will subsequently need this very expensive refrigerant to be used when recharging. To my mind the word 'Potential' in the GWP might better have been underlined.


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