Refrigerant Environmental Impact
Fluorocarbon refrigerants impact the environment in two main ways: ozone layer depletion and global warming.
The ozone depletion potential (ODP) is the ratio of the potential impact on ozone of a chemical compared to the impact of the same mass of CFC-12, with the latter having an impact of 1.
| CFCs |
Since CFCs contain no hydrogen in molecules, they are stable in the atmosphere. This means they cannot be easily broken down until they reach the stratosphere and thus have a high ODP. |
| HCFCs |
Since they contain hydrogen in molecules, HCFCs can be broken down relatively easily in the atmosphere and thus have a low ODP. |
| HFCs |
Since they contain no chlorine or bromine, HFCs have an ODP of zero. |
Refrigerants (Fluorocarbons) Contribute to Global Warming
Global warming refers to a phenomenon in which infrared rays are absorbed by molecules in CO2 and methane, as well as air conditioner refrigerants like CFCs, HCFCs, and HFCs. This prevents heat from escaping the Earth's surface.
The Earth radiates infrared rays from being warmed by the sun's rays in the daytime. |
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These infrared rays should be absorbed in outer space, but before they get there they are instead absorbed within the Earth's atmosphere. |
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The Earth’s surface gets warmer.
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Major Global Warming Substances and GWP (Global Warming Potential)
The potential impact that substances have on global warming is generally shown by their GWP (global warming potential). GWP is calculated as the integrated value of the potential warming impact of a substance compared to the impact of the same amount of CO2 over a period of time. Usually 100 year values are used.
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:Substances covered by the Kyoto Protocol |
| Global warming substances |
Atmospheric life |
GWP*
CO2=1
Atmospheric life:120years
IPCC2001 |
| 20"N'l |
100"N'l |
500"N'l |
| PFC14 |
50000 |
5210 |
7390 |
11200 |
| SF6 |
3200 |
15100 |
22200 |
32400 |
| NF3 |
740 |
12300 |
17200 |
20700 |
| HFC23 |
270 |
12000 |
14800 |
12200 |
| HFE125 |
136 |
13800 |
14900 |
8490 |
| CFC12 |
100 |
11000 |
10900 |
5200 |
| HFC125 |
29 |
6350 |
3500 |
1100 |
| HFC134a |
14 |
3830 |
1430 |
435 |
| CH4(Methane) |
12 |
72 |
25 |
7.6 |
| HCFC22 |
12 |
5160 |
1810 |
549 |
| HFC32 |
4.9 |
2330 |
675 |
205 |
* From IPCC Fourth Assessment Report The Kyoto Protocol uses GWP from the Second Assessment Report of the IPCC.
In addition to the six substances covered by the Kyoto Protocol, there are other global warming substances.
Global warming impact differs from substance to substance. This difference is largely due to the atmospheric life of each substance: the longer the atmospheric life, the greater the increase in global warming potential (GWP) over time.
PFCs (perfluorocarbons) and SF6 (sulfur hexafluoride), which contain no hydrogen molecules, have an atmospheric life ranging from several thousand years to several tens of thousands of years. Compare this with HFCs, whose molecules contain hydrogen. HFC125, the major component of HFC blend refrigerants, has an atmospheric life of 29 years, while the atmospheric life of HFC32 is only five years. If we compare HFC125 and PFC14, their 100-year value GWPs are 3400 and 5700, respectively, not that big a difference. But if we compare their 500-year values, the GWP of PFC14 jumps to eight times that of HFC125. So we can see that the effect of atmospheric life on GWP becomes increasingly greater over longer periods of time.
HFC134a is a refrigerant that is used as a substitute for CFC12 in car air conditioners and refrigerators. The use of this substitute results in global warming potential dropping from 10,600 to 1,300 (100-year values), a huge difference.
Ozone Depletion Potential of Refrigerants (Fluorocarbons)
