There is a possibility for comparison and verification of the results with the sectoral approach when
it is applied the reference approach for determination of ÑÎ2 emissions from fuel combustion.
First step in the Reference Approach is calculating the gross consumption using the following
formula:
Gross consumption = Production + Import – Export – International Bunkers – Provision Change
In the above equation the fuels are presented in natural fuel units (tons, m3, etc.) from the Energy
Balance. The conversion to energy units – TJ is done using conversion factors provided in the IPCC
Guidelines. Local conversion factors are applied only for local coal.
In the second step the determination of CO2 emissions is applied. In general, the emission factors
provided in the Revised IPCC Guidelines are applied.
For the latest few year research was carried out on the influence of some country specific emission
factors. The comparative estimations of CO2 emissions showed variation within 3 %.
Third step in this approach is correction of overall CO2 emissions by excluding emissions from
fuels used as feedstock and for non-energy use. These emissions are estimated using the same
conversion and emission factors as for fuels used for energy.
In
Table A4.1 are presented the CO2 emissions from the Energy Sector estimated both by the
Reference and the Sectoral Approach.
The comparison between the overall emissions in these two approaches varies within 1.4 – 1.7 %
for the last three years under GHG inventory.
The differences between the emissions from the two approaches related to the main type of fuels are
a result of the differences in the Fuel Balance. For example, the differences between the liquid fuels
vary within 2 – 10 % for the latest years and they are bigger for the Reference Approach. The
differences are considerably smaller – under 2 % for the solid fuels. There are also differences
between the gas fuels and vary within 3 – 4 %. The presented situation is very different for the
period till the year 1997.
Main causes for the difference between Reference and Sectoral Approaches
These differences are mainly due to:
- Differences in the methodological approach;
- Different quantities of consumed fuels, including not taking into account the losses
during fuel transformation in the sectoral approach;
- Different conversion factors for fuel conversion from natural units to energy units;
- Different emission factors for different combustion technologies used in the
sectoral approach.
- Sensibility of the ÑÎ2 emissions to the distribution of the petrol products produced
in the refinery and to the carbon content of the crude petrol;
Recalculations and corrections of mistakes
As a result of the recalculations there is a possibility for correction of mistakes and quality
improvement of the calculated GHG emissions.
In Table A4.2 are presented the comparative ÑÎ2
emission assessments from fuel combustion for the last four National Inventory Reports for the
years 1999-2003.
The analyses of
Table A4.2 give opportunity for overall assessment of the result of the presented in
chapter 10 preconditions for carrying out the recalculations. In quantity expression it showed that
ÑÎ2 emissions are higher for the period after 1999 with 5 – 7 % due to the recalculations. For the
base year the result is opposite – the emissions are lower with 4 %.
Reference Approach and comparison with the Sectoral Approach
In
Table A4.3 are presented the reported emission differences in the Reference Approach and
Sectoral Approach for the last four National Inventory Reports.
The analysis of the Table shows overall improvement of the quality assessment of sum ÑÎ2
emissions. It is expressed in reduction of the differences between the two approaches for all the
inventory years in 2005 National Inventory Report compared to 2004 National Inventory Report.
The year 1991 is the only exception.
