1.1 Introduction
According to the definition of Good Practice Guidance, key sources of GHG emissions are these
sources which are responsible for 95 % of the sum of aggregated GHG emission expressed in ÑÎ2-
eq. in the country.
The key sources are defined according to the IPCC classification. Otherwise there are possibilities
for determine key sources that in superior degree are correspondent to the structure of the fuels and
the activities in the country – sources of GHG emissions. This is the reason for the appliance of the
methods for determination of the list of the key sources for Bulgaria in line with the practice in the
country.
By method type Tier 1 are defined key sources accounting two rules:
- Rule A – Level assessment of the GHG emissions in absolute value expressed in
Gg;
- Rule B – Trend assessment of the emissions from the base year till the current year
of the inventory.
In general, by the method from type Tier 1 are arranged emission sources according to the rules
mentioned above. By applying rule A is used information for the volume of the source emissions
only for the current year of the inventory. In this sense it gives the most complete assessment of the
key sources for the current year.
The application of rule B requires information for the GHG emissions for the base year in the
country. That means that the trend assessment includes additional information and gives the
possibility for thorough analysis of the key sources.
The application of method from type Tier 2 supposes the introduction of uncertainty assessments
for each source of GHG emissions. After this an arrangement of these sources is done in accordance
with the above mentioned rules A and B. As expected, this method increases the weight of such
sources of emissions which are more incorrect. In this sense a contradiction can occur as for
example – more insignificant source (with lower level of GHG emissions) to stand at fore-place in
the list of key sources due to its higher inaccuracy.
The comparison with the list of key sources (by method Tier 1, Rule A) given in the previous 2004
Submission presents the following:
- Method from type Tier 2 for key sources assessment is additionally applied;
- The source “Fugitive emissions from the petrol and gas systems ” is dropped out
from the new list;
- Sources “Methane from Wastewater treatment” and “ÑÎ2 from non-energy use of
natural gas” are included in the new list.”
1.2 Tier 1 method for Assessment of Key Sources.
In
Table A1.1 and Table A1.2 are presented lists with the key sources determined in accordance
with the rules A and B.
The analysis of the Table A1.1 shows that sum number of the key sources is 19 from total 39
sources. They are ordered in places by their growth in the first row of the table. This row is called
primary with its symbol T1 – l.
A big difference is observed between the first and the following key sources in the primary row.
Whereas the first source renders 36 % of the total emissions in the country, the second one gives 9
% and the third one – 8 %. Frequently, for the purposes of different analyses of the GHG emissions
are searched these key sources which give over 55 % of the total emissions. For the Bulgarian
inventory these sources turned out to be the first four ones.
The order of the key sources accounting the emission trend is presented in Table A1.2. The table’s
analysis and its comparison with the upper table show the following changes:
- The total number of key sources has decreased with 18 numbers;
- 4 sources have dropped out from the list with key sources and 3 more are included;
- There is a re-arrangement of the key sources – some of them are in upper place
(from 5th and 6th relatively to a 2nd and 3rd), others are in lower places (from 2nd and
3rd to a 4th and 9th place).
In the last column of Table A1.2 is given the order of the sources in line with the Rule B (with a
designation T1-t) and in the first column are the numbers of the sources from the primary row.
A considerable step upper have such sources as “Others - total” – from 39th place to a 6th place and
“CO2 from combustion in the transport and other type of transport” – 17th place to a 5th place, etc.
The determination of the key sources according to this rule leads to an accounting of the rate of
change of each source for the past period expressed in its trend towards the base year. This brings
the opportunity for additional assessments of the quality and value of the key sources. For example,
the key sources which render over 55 % of the assessment of the sum trend are only the first three
sources.
1.3 Method Tier 2 for Assessment of the Key Sources
With the use of the uncertainty assessments for each key source as a weight factor/coefficient is
done a new order of the key sources. This is the core of the method from type Tier 2 for determine
of key sources described in the Good Practice Guidance.
In
Table A1.3 is presented the list of key sources after the application of Rule A. In the last column
are given the serial numbers from the list with designation T2-l.
In the order of the key sources in the upper table are present the following changes in comparison
with the primary row:
- the total number of key sources is decreased with 16 numbers;
- 5 sources are out the list of the key sources and two others are included;
- there is a re-order of the key sources – some are at upper place (from 20,15,12 and
14 relatively to a 3,4,5 and 6 place) and others are come down (from 1,2 and 3 to a
7,13 and 12 place);
It is evident that the use of the uncertainties as weight coefficients gives more priority to the
incorrect emission sources as are the emissions from nitric oxides from soils, emissions from the
nitric acid production and other similar.
In the
Table A1.4 is presented the list of key sources received of the application of Rule B. In the
last are given the serial numbers of the list with designation T2-t.
In the order of the key sources according to this approach in the upper table are shown the biggest
changes compared to the primary row:
- the total number of the key sources is decreased with 16 numbers;
- 8 sources were come out of the list with the key sources and 5 more are included;
- there is a significant re-order of the sources related to the solid wastes and
agricultural soils – from 6, 15 and 20 place, they moved to the first three places;
- significant sources of GHG emissions are come down notably – from 1, 2, and 3
place relatively to a 5, 13, and 22nd place
Obviously, the use of the uncertainties as weight coefficients in combination with the emission
trend toward the base year shows a completely different picture of the key sources compared to the
assessments by the method type Tier 1 in which the emission level is accounted.
The overall conclusion from the analysis of the key sources by the two methods is that it is possible
to cover wilder range of characteristics/peculiarities of this index category the GHG inventory.
