3.5.4.4 HFC-23 Emissions from HCFC-22 Production
HFC-23 is generated as a by-product during the manufacture of HCFC-22 and emitted
through the plant condenser vent. There are about 20 HCFC-22 plants globally.
Additional new plants are expected in developing countries as CFC production
plants are converted to comply with the Montreal Protocol and demand for refrigeration
grows. Although HCFC-22 is an ozone-depleting chemical and production for commercial
use will be phased out between 2005 and 2040, production as a feedstock chemical
for synthetic polymers will continue.
Technologies available to reduce emissions of HFC-23 have been reviewed by
the Research Triangle Institute (RTI, 1996; Rand et al., 1999) and March Consulting
Group (March Consulting, 1998). Two emission reduction options were identified.
- Optimization of the HCFC-22 production process to minimize HFC-23 emissions.
This technology is readily transferable to developing countries. Process optimization
is relatively inexpensive and is demonstrated to reduce emissions of fully
optimized plants to below 2% of HCFC-22 production. Nearly all plants in developed
countries have optimized systems.
- Thermal destruction technologies are available today and can achieve emissions
reductions of as high as 99%, although actual reductions will be determined
by the fraction of production time that the destruction device is actually
operating. Cost estimates are 7 ECU/tC for the EU (March Consulting, 1998,
8% discount rate).
3.5.4.5 Emissions of SF6 from the Production, Use and Decommissioning
of Gas Insulated Switchgear
SF6 is used for electrical insulation, arc quenching, and current
interruption in electrical equipment used in the transmission and distribution
of high-voltage electricity. SF6 has physical properties that make
it ideal for use in high-voltage electric power equipment, including high dielectric
strength, excellent arc quenching properties, low chemical reactivity, and good
heat transfer characteristics. The high dielectric strength of SF6
allows SF6-insulated equipment to be more compact than equivalent
air-insulated equipment. An SF6-insulated substation can require
as little as 10% of the volume of an air-insulated substation. Most of the SF6
used in electrical equipment is used in gas-insulated switch gear and circuit
breakers. SF6 in electric equipment is the largest use category of
SF6 with global estimates of over 75% of SF6 sales going
to electric power applications (SPS, 1997). Options to reduce emissions include
upgrading equipment with low emission technology, and improved handling during
installation maintenance and/decommissioning (end-of-life) of SF6-insulated
equipment, which includes the avoidance of deliberate release and systematic
recycling. Guidelines on equipment design to allow ease of gas recycling, appropriate
gas handling and recycling procedures, features of gas handling and recycling
equipment, and the impact of voluntary emission reduction programmes are contributing
to the reduction of emissions from this sector (Mauthe et al, 1997; Causey,
2000).
Significant emissions may also occur during the manufacturing and testing of
gas-insulated switch gear when the systems are repeatedly filled with SF6
and re-evacuated (Harnisch and Hendriks, 2000). Historically these emissions
have been in the range of 30%-50% of the total charge of SF6. The
existence and appropriate use of state-of-the art recovery equipment can help
to reduce these emissions down to at least 10% of the total charge of SF6.
3.5.4.6 Emissions of SF6 from Magnesium Production and Casting
In the magnesium industry, a dilute mixture of SF6 with dry air
and/or CO2 is used as a protective cover gas to prevent violent oxidation
of the molten metal. It is assumed that all SF6 used is emitted to
the atmosphere. 7% of global SF6 sales is estimated to be for magnesium
applications (SPS, 1997). Manufacturing segments include primary magnesium production,
die casting, gravity casting and secondary production (i.e., scrap metal recycling).
Because of differing production processes and plant scale, emission reduction
potential varies across manufacturing segments. Emissions of SF6
in magnesium casting can potentially be reduced to zero by switching to SO,
a highly toxic and corrosive chemical used over20 years ago as a protective
cover gas. Harnisch and Hendriks (2000) estimate that net costs of switching
from SF6 to SO2-based cover gas systems are about US$1/tCeq,
but as a result of the high toxicity and corrosivity of SO2 much
more careful handling and gas management is required. In many cases the specific
usage of SF6 can be reduced by operational changes, including moderate
technical modifications (Maiss and Brenninkmeijer, 1998). Companies may also
reduce SF6 emissions and save money by carefully managing the concentration
and application of the cover gas (IMA, 1998). A study is currently beingundertaken
to identify and evaluate chemical alternatives to SF6 and SO2
for magnesium melt protection (Clow and Hillls, 2000).
3.5.4.7 Some Smaller Non-CO2 Emission Reduction Options
There are a number of small emission sources of SF6, some of which
are considered technically unnecessary. For example, SF6 has been
used as a substitute for air, hydrogen or nitrogen in sport shoes and luxury
car tyres to extend the lifetime of the pressurized system. SF6 in
sport shoes has been used by a large global manufacturer for over a decade under
a patented process. Soundproof windows have been manufactured with SF6
in several countries in Europe.
Small quantities of SF6 are used as a dielectric in the guidance
system of radar systems like the airborne warning and control system (AWACS)
aircraft and as a tracer gas for pollutant dispersion studies. Small quantities
of PFCs and SF6 are used in medical applications such as retina repair,
collapsed lung expansion, and blood substitution (UNEP, 1999).
3.5.4.8 Summary of Manufacturing Industry GHG Emission Reduction Options
An overview of greenhouse gas emission reduction options in manufacturing industry
due to fuel switching, carbon dioxide removal, material efficiency improvements,
and reduction of non-CO2 greenhouse gases emissions practices is
presented in Table 3.21, which complements information
from Table 3.19.
| Table 3.21: Overview of greenhouse gas
emission reduction options in industry (excludes energy efficiency improvement,
see Table 3.19). Note that the scales are not
linear. |
 |
|
Sector
|
Technology
|
Potential in 2010
|
Emission reduction costs
|
Remarks
|
| |
|
All industry
|
Fuel switching
|
|
?
|
Rough estimate
|
|
Fertilizer, refineries
|
Carbon dioxide removal
|
|
+
|
Excludes carbon dioxide removal from flue
gases
|
|
Basic materials
industries
|
Material efficiency improvement
|
|
-/+/++
|
First estimate of potentials; option is not yet
worked out in detail
|
|
Cement industry
|
Application of blended cements
|
|
-
|
Excludes emission reduction measures taken
before the year 2000
|
|
Chemical industry
|
Nitrous oxide emission reduction
|
|
+
|
|
Aluminium industry
|
PFC emission reduction
|
|
+/-
|
|
Chemical industry
|
HFC-23 emission reduction
|
|
+
|
|
| |
| |
