HFCs, PFCs and SF6 Emission Estimates
The UK emissions of HFCs are shown in Table 2.7. The emissions are reported in terms of their global warming potential (GWP). The HFC emissions comprise many species each with its own GWP, hence it is more helpful to express emissions in terms of GWP as CO2 equivalent. It is not currently possible to give emission estimates for individual HFCs because some of these are considered commercially sensitive data within the industries involved.
HFCs had limited usage primarily as refrigerants blended with CFCs. However, CFCs and HCFCs are being phased out under the Montreal protocol, and hence HFCs are now being used increasingly as:
Salway (2001) reports the emissions, estimation methodology and ongoing improvements in some detail. The UK reports both actual and potential emissions of HFCs, although here only the actual emissions are presented.
Refrigeration is the largest source and contributed 51% of the total in 1999. Here emissions arise due to leakage from refrigeration and air conditioning equipment during its life time and from losses during manufacture and the recovery of the refrigerants on decommissioning.
There has been a large decrease in emissions from "Halocarbon production" from 1998 to 1999. This is a result of an abatement system fitted to a plant producing HCFCs.
In the case of closed foams where the fluid is retained within the foam there will be some leakage from the foam during its lifetime and on disposal but with open foams all losses occur during manufacture. Since 1990, the use of HFCs in aerosols has greatly increased, and this source sector now accounts for 22% of the total emission.
The total 1999 HFC UK emission has decreased by 46% compared with the 1990 emission and is characterised by the increasing use of HFCs offset by the large reduction in emissions from halocarbon production between 1998 and 1999.
Table 2.7 UK Emissions of HFCs (Mtonnes CO2 equivalent)
|
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
1999% |
|
|
Halocarbon production |
11.4 |
11.8 |
12.3 |
12.8 |
13.3 |
14.0 |
14.3 |
15.6 |
16.5 |
1.9 |
31% |
|
Foams & Firefighting |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0 |
0.1 |
1% |
|
Refrigeration |
0 |
0 |
0 |
0.1 |
0.4 |
0.8 |
1.2 |
1.8 |
2.3 |
2.8 |
45% |
|
Aerosols1 |
0 |
0 |
0 |
0 |
0.1 |
0.4 |
0.8 |
1.0 |
1.3 |
1.4 |
22% |
|
Total |
11.4 |
11.9 |
12.3 |
12.9 |
13.8 |
15.2 |
16.3 |
18.4 |
20.2 |
6.2 |
100% |
1
Includes metered dose inhalers.
Table 2.8 shows the UK emissions of PFCs reported as Mtonnes CO2 equivalent. It is not currently possible to give emission estimates for individual PFCs because some of these are considered commercially sensitive data within the industries involved. PFCs had limited usage prior to the phase out of CFCs in the electronics and electrical industry. PFCs are now used in:
Other uses include
Other minor uses of CFCs, which now use PFCs, were in cosmetics and as a tracer gas.
The largest source of PFCs for 1999, representing over half of the total, is from the electronics sector, where emissions arise from the manufacture of semiconductors. PFCs are also formed as a by-product of aluminium smelting. Emission from this sector account for 31% of the UK total in 1999. The emissions are caused by the anode effect which occurs when alumina concentrations become too low in the smelter. This can cause very high electrical current and decomposition of the salt - fluorine bath. The fluorine released reacts with the carbon anode, creating PFC compounds CF4 and C2F6 . Total emissions have declined by 70% since 1990 reflecting steps taken by the industry to reduce emissions.
Table 2.8 UK Emissions of PFCs (Mtonnes CO2 equivalent)
|
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
1999% |
|
|
Fire-fighting |
0 |
0 |
0 |
0 |
0 |
0 |
0.001 |
0.002 |
0.003. |
0.004 |
1% |
|
Aluminium Production |
2.031 |
1.557 |
0.745 |
0.474 |
0.406 |
0.372 |
0.298 |
0.237 |
0.223 |
0.21 |
31% |
|
Refrigeration |
0 |
0 |
0 |
0.001 |
0.005 |
0.009 |
0.014 |
0.019 |
0.025 |
0.029 |
4% |
|
Electronics & Training Shoes |
0.250 |
0.233 |
0.214 |
0.336 |
0.569 |
0.712 |
0.593 |
0.403 |
0.401 |
0.435 |
64% |
|
Total |
2.281 |
1.790 |
0.959 |
0.811 |
0.980 |
1.094 |
0.905 |
0.661 |
0.652 |
0.678 |
100% |
SF6 is used in the following applications:
Table 2.9 shows the UK emissions of SF6. The largest source is from magnesium manufacture, where SF6 is used as a cover gas. It is not possible to recover the SF6, and hence the total consumption of SF6 is released to atmosphere- emissions from this sector account for 55% of the UK total in 1999. Emissions in 1999 are higher than those in 1990 because SF6 has been increasingly used in place of SO2.
The other main sources are from the manufacture of trainers, and electrical/electronic equipment. The use of SF6 as a cushioning in trainers will be phased out in the near future. Emissions from the electrical insulation arise during the manufacture and filling of electrical switchgear and from leakage and maintenance during the equipment’s lifetime. This application has only been in use for the last 20 to 30 years and little of the equipment has been decommissioned. It is expected that users will take great care over future fluid recovery so that emissions will be minimised. SF6 emissions have increased by 81% since 1990.
Table 2.9 UK Emissions of Sulphur Hexafluoride (tonnes)
|
1990 |
1991 |
1992 |
1993 |
1994 |
1995 |
1996 |
1997 |
1998 |
1999 |
1999% |
|
|
SF6 Cover Gas |
20.0 |
20.0 |
20.0 |
20.0 |
25.0 |
25.0 |
30.0 |
30.0 |
30.0 |
30.0 |
55% |
|
Electrical Insulation |
5.3 |
5.6 |
6.0 |
6.3 |
6.4 |
8.4 |
8.9 |
8.2 |
8.8 |
9.5 |
17% |
|
Electronics & Trainers |
5.0 |
6.8 |
8.9 |
10.9 |
13.0 |
14.0 |
14.2 |
14.7 |
15.1 |
15.5 |
28% |
|
Total |
30.3 |
32.5 |
34.8 |
37.2 |
44.4 |
47.4 |
53.2 |
52.8 |
53.9 |
55.0 |
100% |