THE GLOBAL CHALLENGE OF REPLACING CFCs
Editor's Note: Lily C. ('15) wrote this short paper about the difficulties of replacing CFCs despite their damage to the ozone layer for her Organic Chemistry class
Chlorofluorocarbons, better known as CFCs, were once widely used in refrigeration, air conditioning, and aerosol cans. This group of molecules, when discovered, was seen as a solution to many of the problems in industrial chemistry, particularly in the development of refrigerators. However, we now know that CFCs have played a significant role in depleting a portion of the earth’s ozone layer, which plays an important role in protecting us from UV radiation. Ozone depletion is a global problem, and thus, the international community has taken steps to address it. The Montreal Protocol from 1987 requires signing nations to phase out use of CFCs. We would like to think that this is a simple solution, but for a number of reasons, replacing CFCs has been a difficult task.
CFCs have multiple properties which marked them as “ideal” refrigerants (compounds that undergo an evaporation-compression cycle). They compress into liquid and vaporize into gas at a temperature ideal for refrigeration, and absorb large amounts of heat when they vaporize. While some of the previous refrigerants involved safety issues such as flammability or toxicity, CFCs appeared to pose no risk. CFCs are also very stable and unreactive. While we now know that this property contributes to their detrimental effect on the ozone layer, this made them appealing refrigerants. Additionally, CFCs are nearly odorless, while many previous refrigerants smelled horrible.
Hydroflourocarbons (HFCs) are one group of molecules that have been (and still are) widely used to replace CFCs. These compounds, while similar to CFCs, do not affect the ozone layer: “The HFCs are considered one of the best substitutes for reducing stratospheric ozone loss because of their short lifetime and lack of chlorine” (Elkins, 1999). While replacing CFCs helps to solve the problem of atmospheric ozone, HFCs are greenhouse gases, and trap a lot of heat in the air, even more so than CO2 (Fogarty, 2011). Their continued widespread use would likely worsen and accelerate global warming.
Another similar group of compounds that is used to replace CFCs is HCFCs (hydroflouroclorocarbons). Less of these molecules reach the ozone layer because they are more reactive, however, they do contribute (less so than CFCs) to ozone depletion. HCFCs, like HFCs, are also greenhouse gases. In light of this, the 1992 Copenhagen amendment to the Montreal Protocol calls for nations to cut out use of HCFCs by 2030 (Elkins, 1999). In addition to concerns about global warming and ozone, CFCs and HCFCs “are not as effective as refrigerants, and they require up to 3 percent more energy for the refrigeration cycle” (Le Couteur & Burreson, 2004, p. 319).
Replacing CFCs has been a difficult task. The most popular and well studied alternatives that we have discovered (HFCs and HCFCs) have been shown to have significant downsides for our environment. In addition to a thriving black market, many nations still use CFCs because they are inexpensive, easy to produce, and switching to alternatives would be a costly process. Unfortunately, there is still work to be done before we can have an efficient, environmentally friendly alternative to CFCs.
CFCs have multiple properties which marked them as “ideal” refrigerants (compounds that undergo an evaporation-compression cycle). They compress into liquid and vaporize into gas at a temperature ideal for refrigeration, and absorb large amounts of heat when they vaporize. While some of the previous refrigerants involved safety issues such as flammability or toxicity, CFCs appeared to pose no risk. CFCs are also very stable and unreactive. While we now know that this property contributes to their detrimental effect on the ozone layer, this made them appealing refrigerants. Additionally, CFCs are nearly odorless, while many previous refrigerants smelled horrible.
Hydroflourocarbons (HFCs) are one group of molecules that have been (and still are) widely used to replace CFCs. These compounds, while similar to CFCs, do not affect the ozone layer: “The HFCs are considered one of the best substitutes for reducing stratospheric ozone loss because of their short lifetime and lack of chlorine” (Elkins, 1999). While replacing CFCs helps to solve the problem of atmospheric ozone, HFCs are greenhouse gases, and trap a lot of heat in the air, even more so than CO2 (Fogarty, 2011). Their continued widespread use would likely worsen and accelerate global warming.
Another similar group of compounds that is used to replace CFCs is HCFCs (hydroflouroclorocarbons). Less of these molecules reach the ozone layer because they are more reactive, however, they do contribute (less so than CFCs) to ozone depletion. HCFCs, like HFCs, are also greenhouse gases. In light of this, the 1992 Copenhagen amendment to the Montreal Protocol calls for nations to cut out use of HCFCs by 2030 (Elkins, 1999). In addition to concerns about global warming and ozone, CFCs and HCFCs “are not as effective as refrigerants, and they require up to 3 percent more energy for the refrigeration cycle” (Le Couteur & Burreson, 2004, p. 319).
Replacing CFCs has been a difficult task. The most popular and well studied alternatives that we have discovered (HFCs and HCFCs) have been shown to have significant downsides for our environment. In addition to a thriving black market, many nations still use CFCs because they are inexpensive, easy to produce, and switching to alternatives would be a costly process. Unfortunately, there is still work to be done before we can have an efficient, environmentally friendly alternative to CFCs.
Couteur, P. L., & Burreson, J. (2004). 16. Chlorocarbon compounds. In Napoleon's buttons: How 17 molecules changed history. New York: Jeremy P. Tarcher/Putnam.
Elkins, J. W. (1999). Halocarbons and other atmospheric trace species. In The Chapman & Hall Encyclopedia of Environmental Science. Retrieved March 1, 2015, from http://www.esrl.noaa.gov/gmd/hats/publictn/elkins/cfcs.html
Fogarty, D. (2011, November 21). Beware climate change risk from aircon, fridge gases: U.N. Retrieved from http://www.reuters.com/article/2011/11/21/us-climate-gases- idUSTRE7AK0GO20111121
Elkins, J. W. (1999). Halocarbons and other atmospheric trace species. In The Chapman & Hall Encyclopedia of Environmental Science. Retrieved March 1, 2015, from http://www.esrl.noaa.gov/gmd/hats/publictn/elkins/cfcs.html
Fogarty, D. (2011, November 21). Beware climate change risk from aircon, fridge gases: U.N. Retrieved from http://www.reuters.com/article/2011/11/21/us-climate-gases- idUSTRE7AK0GO20111121
