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SECTION
5 ASSIMILATIVE CAPACITY CAPITAL STOCK
| 5.4 |
Assimilative
Capacity of Air (including Noise) |
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Greenhouse
Gases
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| 5.4.1.23 |
Carbon
dioxide (CO2) is the most significant greenhouse
gas (GHG) emitted in Hong Kong. Using the
Global Warming Potential system, which is
a means for comparing different greenhouse
gases based on their relative atmospheric
heating, CO2 emissions constitute 83-88%
of the total emissions of GHGs between 1990
and 1997 (ERM 1999f). Other contributors
include methane (CH4, 11-14%), nitrous oxide
(N20, 1-2%) and a combined contribution
of around 1% from emissions of hydrofluorocarbons
(HFCs), perfluorocarbons (PFCs) and sulphur
hexafluoride (SF6). The emissions of these
gases, in terms of their CO2 equivalent,
for the period 1990-1997 are detailed in
Table 5.4f.
| Table
5.4f Total Greenhouse Gas Emissions
in Hong Kong SAR, 1990-1997 ( Thousand
tonnes CO2 equivalent) |
| Year |
CO2 |
CH4 |
N2O |
HFCS |
SF6 |
PFCS |
Total |
| 1990 |
33,121 |
4,494 |
489 |
- |
- |
- |
38,104 |
|
86.9% |
11.8% |
1.3% |
- |
- |
- |
|
| 1991 |
35,461 |
4,691 |
500 |
- |
- |
- |
40,652 |
|
87.2% |
11.5% |
1.2% |
- |
- |
- |
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| 1992 |
40,075 |
4,930 |
530 |
- |
- |
- |
45,535 |
|
88.0% |
10.8% |
1.2% |
- |
- |
- |
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| 1993 |
40,710 |
5,190 |
553 |
- |
- |
- |
46,453 |
|
87.6% |
11.2% |
1.2% |
- |
- |
- |
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| 1994 |
34,202 |
5,417 |
557 |
- |
- |
- |
40,177 |
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85.1% |
13.5% |
1.4% |
- |
- |
- |
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| 1995 |
34,908 |
5,550 |
665 |
214 |
112 |
0.73 |
41,450 |
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84.2% |
13.4% |
1.6% |
0.52% |
0.27% |
0.0018% |
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| 1996 |
33,813 |
5,633 |
767 |
269 |
112 |
0.95 |
40,596 |
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83.3% |
13.9% |
1.9% |
0.66% |
0.28% |
0.0023% |
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| 1997 |
32,565 |
5,524 |
965 |
339 |
113 |
1.24 |
39,508 |
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82.4% |
14.0% |
2.4% |
0.86% |
0.29% |
0.0031% |
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Note:
Inventories of HFCS, PFCS and SF6 are required
by the IPCC only after 1995.
Source: ERM(1999f)
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| 5.4.1.24 |
Territorial
GHG emissions have exhibited a decline from
the period from 1993-1997, principally due
to an increase in the amount of power supplied
from nuclear sources (eg Daya Bay in Guangdong)
offsetting fossil fuel generated electricity,
as well as the commissioning of a new gas
fired power station at Black Point in 1996
that replaced some of the existing coal-fired
capacity. Within this overall trend, the
relative contribution of CO2 to total GHG
emissions declined in comparison with the
other five pollutants during the period
from 1992 to 1997.
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| 5.4.1.25 |
The
key sources of GHG emissions in Hong Kong
(ERM 1999f) can be categorised as follows.
- Energy
industries, comprising combustion of fossil
fuels by power stations, manufacturing
industries, construction and transport.
This sector accounted for 96.9% of CO2
emissions, 1.2% of CH4 emissions and 78%
of N2O emissions in 1997.
- Industrial
processes which produce emissions from
the physical/chemical transformation of
materials (eg cement manufacturing and
town gas production), which contributed
to 2.8% of CO2 emissions in 1997.
- Agricultural
activities including livestock and manure
management, cultivation, burning and soils
which produce less than 0.5% of CO2 emissions,
0.5% of CH4 emissions and 0.7% of N2O
emissions in 1997.
- Waste
handling, including degradation of waste
in landfills, incinerators and wastewater
and sludge treatment processes. These
processes accounted for 0.3% of CO2 emissions,
98.4% of CH4 emissions and 21.3% of N2O
emissions in 1997.
- Land
use change and forestry (albeit limited
in Hong Kong - see Section 3.2 and 3.3
for discussions on land use and silviculture
respectively) which can contribute to
CO2 uptake through sequestration of carbon,
although this is estimated to be equivalent
to around 0.1% of the total CO2 emitted
per annum.
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| 5.4.1.26 |
Despite
recent reductions in annual GHG emissions,
projections undertaken for the Greenhouse
Gas Emission Control Study (ERM 1999f), suggest
that emissions are likely to increase more
rapidly between 2000 and 2010 than has been
witnessed between 1990 and 2000. These increases
are based principally upon projected increases
in energy consumption through demand for power
generation and increased road transport (see
Section 3.6 for a discussion on energy sources
and requirements), such that GHG emissions
would increase (in CO2 equivalent terms) from
38.1 Mt in 1990 to 37.5 Mt in 2000 and 56.1Mt
by 2010 - or an increase of 47% by 2010 compared
with 1990 levels. These projections are based
on implicit assumptions in the modelling that
historical trends in energy consumption are
an acceptable representation of likely future
patterns of consumption, and on assumptions
relating to data use, principally that projections
of economic and social development in Hong
Kong are accurate and that the latest data
on actual fuel combustion are representative
of future fuel use (ERM 2000d). The estimates
for future GHG emissions presented in the
above sections should be treated with caution
since the consultants research for the GHG
emissions study has yet to be completed or
endorsed by EPD. |
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