CHLOROFLUOROCARBONS AND THE DIFFICULTY OF PRODUCING SAFE REPLACEMENT
Editor’s note: Liam S. (‘18) wrote this piece for his Organic Chemistry class where they studied the environmental impacts of chlorofluorocarbons.
The invention of refrigeration transformed the world’s economy and culture, bringing with it TV dinners and frozen Australian lamb. During the 19th century, there were many compounds vying for roles as refrigerants –ether, ammonia, methyl chloride, and sulfur dioxide. For a compound to be classified as a refrigerant, it must vaporize at low temperatures while absorbing large amounts of heat. It then must be able to condense into a liquid with compression. These compounds all fit the criteria for a refrigerant, but were toxic, flammable, odorous, or decomposed. CFCs (chlorofluorocarbons) produced in the 1920s were seen as ideal refrigerants because they did not have any of the previously described characteristics. Not until the late 20th century, after years of production, was it discovered that CFCs were harmful to the ozone layer, eventually leading to the Montreal Protocol, which banned CFC consumption and use (Le Couteur and Burreson, 2004). Although CFCs were proven to be detrimental to the planet, economic and environmental factors made safe alternatives difficult to produce, as many new products turned out to be equally devastating.
The unreactive properties that made CFCs so useful, also made them destructive. Many of the initial refrigerants’ chemical properties inhibited them from meeting the growing economic demands for refrigeration. The first CFC molecules composed –Freon 12 (CCl2F2), Freon 11 (CCl3F), and Freon 114 (C2Cl2F4)– included one or two carbon atoms along with mixed numbers of chlorine and fluorine atoms. These CFCs were seen as “perfect refrigerants” when first developed, as they were nontoxic, nonflammable, odorless, and cheap to produce, having all the positive characteristics, but none of the negatives that previously plagued refrigerants. Their chemical stability allowed for CFCs to have many different uses, from propellants in spray cans to foaming agents (Le Couteur and Burreson, 2004). Although seemingly innocent, CFCs had unknown consequences. Because of their low reactivity, CFCs don’t break down in the lower atmosphere; instead they rise to the stratosphere where solar radiation eventually ruptures them. When ruptured, the chlorine present in the CFCs reacts with ozone, creating chlorine monoxide and an oxygen molecule. Ozone molecules are naturally destroyed and created by ultraviolet radiation, but when CFCs are emitted, they increase the rate of destruction, resulting in the penetration of solar radiation to the Earth’s surface (Le Couteur and Burreson). Although the stability of CFCs makes them ideal refrigerants, it also makes them harmful.
Economic and environmental factors made the development of alternatives to CFCs challenging. After the Montreal Protocol agreement banning CFCs, a new “perfect refrigerant” was needed. The low reactivity, which made CFCs successful, but destructive, was necessary for a good refrigerant, making the process of creating an alternative all the more complicated. Any alternative, to not destroy the ozone, had to be more reactive to ensure its oxidation in the lower atmosphere. The new compounds also could not harm the environment in other ways, which soon became a significant problem for many replacements. Along with environmental and chemical requirements, an alternative had to be economically friendly. Many of the hydrofluorocarbons alternatives used three percent more energy, making them less desirable to businesses and developing economies (Le Couteur and Burreson). Another factor that made the production of an alternative difficult was that not all countries signed the Montreal Protocol, especially some developing nations who were exempt from the ban on production (Elkins, 1999). Because not every nation was in agreement with the environmental effects of CFCs, there was not a universal demand for alternatives, making the advancement of environmentally and economically friendly replacements harder. The stringent economic and environmental requirements for alternatives to CFCs complicated the development of safe compounds. Combined with these evident factors, the development of alternatives was also hard due to the difficulty in producing a compound without unknown, negative environmental effects.
Some of the alternative compounds produced, although not harmful to the ozone, have similar adverse effects on the environment to that of CFCs. Since the mid-1990s, hydrofluorocarbons compounds (HFCs) were primary alternatives to CFCs (EPA, 2016). Unfortunately, like CFCs, HFCs have a dark side. Fluorinated greenhouse gases, HFCs have extremely high global warming potentials –(HFC-134a), a common refrigerant, has a GWP of 1,430 according to the EPA (2017). Other, natural, refrigerant alternatives have been developed such as ammonia and carbon dioxide. Both compounds do not deplete the ozone, making them viable options, but like the others, have downsides. CO2 has a global warming potential of one, and is another potent greenhouse gas that is already profusely emitted. Ammonia (NH3), although it does not have a global warming potential is toxic and can only be used in closed systems (Larkin and Davies, n.d.). Many of the replacement compounds, although they do not affect the ozone, are just as harmful, if not worse, for the environment than CFCs.
CFCs allowed for the advancement of the world's economy and the standard of living. Once seen as “perfect,” they are now considered destructive. Despite having been proven to be a danger to the planet, the process of replacing CFCs has been difficult due to economic and environmental factors. Many of the alternatives, although being safe in one category, are harmful in others adding layers of complexity to the issue of innovation. In the future, to prevent dangerous chemicals from being implemented, it is critical that there be extensive research investigating external effects of a compound on the environment and people. Global dilemmas, such as the one created by CFCs, help for the scientific and business community to learn, making society more productive, while minimizing the risk of future incidents.
The unreactive properties that made CFCs so useful, also made them destructive. Many of the initial refrigerants’ chemical properties inhibited them from meeting the growing economic demands for refrigeration. The first CFC molecules composed –Freon 12 (CCl2F2), Freon 11 (CCl3F), and Freon 114 (C2Cl2F4)– included one or two carbon atoms along with mixed numbers of chlorine and fluorine atoms. These CFCs were seen as “perfect refrigerants” when first developed, as they were nontoxic, nonflammable, odorless, and cheap to produce, having all the positive characteristics, but none of the negatives that previously plagued refrigerants. Their chemical stability allowed for CFCs to have many different uses, from propellants in spray cans to foaming agents (Le Couteur and Burreson, 2004). Although seemingly innocent, CFCs had unknown consequences. Because of their low reactivity, CFCs don’t break down in the lower atmosphere; instead they rise to the stratosphere where solar radiation eventually ruptures them. When ruptured, the chlorine present in the CFCs reacts with ozone, creating chlorine monoxide and an oxygen molecule. Ozone molecules are naturally destroyed and created by ultraviolet radiation, but when CFCs are emitted, they increase the rate of destruction, resulting in the penetration of solar radiation to the Earth’s surface (Le Couteur and Burreson). Although the stability of CFCs makes them ideal refrigerants, it also makes them harmful.
Economic and environmental factors made the development of alternatives to CFCs challenging. After the Montreal Protocol agreement banning CFCs, a new “perfect refrigerant” was needed. The low reactivity, which made CFCs successful, but destructive, was necessary for a good refrigerant, making the process of creating an alternative all the more complicated. Any alternative, to not destroy the ozone, had to be more reactive to ensure its oxidation in the lower atmosphere. The new compounds also could not harm the environment in other ways, which soon became a significant problem for many replacements. Along with environmental and chemical requirements, an alternative had to be economically friendly. Many of the hydrofluorocarbons alternatives used three percent more energy, making them less desirable to businesses and developing economies (Le Couteur and Burreson). Another factor that made the production of an alternative difficult was that not all countries signed the Montreal Protocol, especially some developing nations who were exempt from the ban on production (Elkins, 1999). Because not every nation was in agreement with the environmental effects of CFCs, there was not a universal demand for alternatives, making the advancement of environmentally and economically friendly replacements harder. The stringent economic and environmental requirements for alternatives to CFCs complicated the development of safe compounds. Combined with these evident factors, the development of alternatives was also hard due to the difficulty in producing a compound without unknown, negative environmental effects.
Some of the alternative compounds produced, although not harmful to the ozone, have similar adverse effects on the environment to that of CFCs. Since the mid-1990s, hydrofluorocarbons compounds (HFCs) were primary alternatives to CFCs (EPA, 2016). Unfortunately, like CFCs, HFCs have a dark side. Fluorinated greenhouse gases, HFCs have extremely high global warming potentials –(HFC-134a), a common refrigerant, has a GWP of 1,430 according to the EPA (2017). Other, natural, refrigerant alternatives have been developed such as ammonia and carbon dioxide. Both compounds do not deplete the ozone, making them viable options, but like the others, have downsides. CO2 has a global warming potential of one, and is another potent greenhouse gas that is already profusely emitted. Ammonia (NH3), although it does not have a global warming potential is toxic and can only be used in closed systems (Larkin and Davies, n.d.). Many of the replacement compounds, although they do not affect the ozone, are just as harmful, if not worse, for the environment than CFCs.
CFCs allowed for the advancement of the world's economy and the standard of living. Once seen as “perfect,” they are now considered destructive. Despite having been proven to be a danger to the planet, the process of replacing CFCs has been difficult due to economic and environmental factors. Many of the alternatives, although being safe in one category, are harmful in others adding layers of complexity to the issue of innovation. In the future, to prevent dangerous chemicals from being implemented, it is critical that there be extensive research investigating external effects of a compound on the environment and people. Global dilemmas, such as the one created by CFCs, help for the scientific and business community to learn, making society more productive, while minimizing the risk of future incidents.
