Dynamics of nitrous oxide emissions from different sources in bulgaria

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Issue: 12 | Dec-2014, Available @ http://www.ijret.org 135
DYNAMICS OF NITROUS OXIDE EMISSIONS FROM DIFFERENT
SOURCES IN BULGARIA
Rozalina Chuturkova1
, Maya Stefanova2
1
Associate Professor, Department of Ecology and Environmental Protection, Technical University, Varna, Bulgaria
2
PhD Student, Department of Ecology and Environmental Protection, Technical University, Varna, Bulgaria
Abstract
Within the present research inventory data has been analyzed regarding nitrous oxide emissions from different source categories
in Bulgaria for the period 2000-2012. The major N2O emission source is agriculture with almost 45 % of the overall N2O
emissions for the monitoring period. In order to reduce N2O emissions from agriculture adequate measures need to be applied
towards improvement of agricultural land’s quality, restructure and modernization of farms and competitiveness increase. N2O
emissions from power sector are almost 16 % of the overall N2O emissions in Bulgaria for the monitoring period and their
reduction require measures for improving national energetic infrastructure, diversifying the energy mix and supply sources. A
solid trend for N2O emission reduction from the sectors of Industrial processes and Road transport has been observed due to the
effective European and national legal restrictions and regulatory mechanisms. Regions at risk in Bulgaria have been defined
where industrial and combustion sources of N2O are concentrated and thus ambient air quality might be significantly
deteriorated. Applying preventive measures for greenhouse gas (including N2O) emission reduction is a step towards fulfillment of
Bulgaria’s commitment under the Kyoto Protocol and the Durban Platform. For the period 2013-2020 Bulgaria has committed
itself into achieving the basic strategic targets of the European Union for 20 % reduction of greenhouse gas emissions, 20 %
enhancement of the energy efficiency and 20 % share of energy from renewable energy sources in the total energy consumption.
The ambitious target of the European Union on climate change is to reduce greenhouse gas emissions with 80 % below their 1990
level by 2050.
Keywords: emission source categories, emission reduction measures, greenhouse gas, nitrous oxide, regions at risk
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1. INTRODUCTION
Nitrous oxide N2O is a greenhouse gas under the Kyoto
Protocol [1] and one of the major reasons for global
warming effect. N2O emission sources vary by technical and
economic characteristics. According to the results of the
European Union greenhouse gas inventory for the period
1990-2010 [2] the dominant N2O emission source is
agriculture, in particular emissions from soil. Other
significant sources are transport, industrial processes
(production of caprolactam and nitric acid) and combustion
of fuels in power sector. Limitation of N2O emissions from
different sources is essential to combat the adverse changes
of the climate system. The most restrictive measures are
imposed to the industrial sector by introducing regimes for
integrated pollution prevention and control [3] and emission
limit values for pollutants that determine the ambient air
quality [4-5]. A key administrative tool of the European
Union for climate change combat is the establishment of a
scheme for greenhouse gas emission allowance trading
within the Community (the Community Scheme) in order to
promote reductions of greenhouse gas emissions in a cost-
effective and economically efficient manner [6].
2. MATERIAL AND METHODS
Within the present research data has been analyzed
regarding N2O emissions from different source categories in
Bulgaria for the period 2000-2012 in order to estimate the
effectiveness of the applied administrative measures for
mitigating the adverse changes of the climate system.
National inventory reports for greenhouse gas emissions [7]
and statistical data for harmful emissions in the atmosphere
from industrial and power sector [8] have been used as data
source. Dynamics of annual N2O emissions for the
monitoring period have been analyzed and compared to
Bulgaria’s common strategic framework for greenhouse gas
emission reduction and climate change combat for the
period 2013-2020 [9]. Data regarding N2O emissions in the
atmosphere from industrial and power sources in certain
areas in Bulgaria has been analyzed in order to define the
regions at risk which need planning and implementation of
additional regulatory measures to achieve a solid trend for
N2O emission reduction.
3. RESULTS AND DISCUSSION
Total N2O emissions (tons) from different source sectors in
Bulgaria for the period 2000-2012 are indicated on Fig. 1.

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Legend:
1. Electrical and thermal energy production and public sector heating 2. Industrial processes
3. Communal heating 4. Road transport
5. Other transport 6. Solid waste treatment and storage
7. Agriculture 8. Natural sources
Fig 1: N2O emissions from different source sectors in Bulgaria for the period 2000-2012
As indicated on Fig. 1 the major source of N2O emissions
for the monitoring period is Agriculture – 221514 tons or
44.6 % of the overall N2O emissions in Bulgaria. Natural
sources come next with 182206 tons or 36.7 % of the
sharing, followed by the power sector – 77078 tons or 15.5
% of the overall N2O emissions for the monitoring period.
The total sum of N2O emissions from these three sectors is
almost 97 % of the overall emissions for the monitoring
period thus defining the focus of Bulgaria’s climate change
combat strategy. The rest 3 % of N2O emissions are
allocated among the source sectors Solid waste treatment
and storage (8031 tons – 1.6 %), Road transport (4800 tons
– 0.97 %), Industrial processes (1503 tons – 0.3 %) and
Communal heating (1405 tons – 0.28 %). The quantity of
N2O emissions from the sector Other transport is negligible
(427 tons – 0.09 %).
N2O emissions (t/y) from 8 different source categories in
Bulgaria for the period 2000-2012 [8] are indicated on Fig.
2-9. Balance methods have been used for N2O emission
calculation in accordance with the latest version of
CORINAIR guidebook [10].

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0
5000
10000
15000
20000
25000
30000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig. 2. N2O emissions (t/y) from Agriculture for the period 2000-2012
12500
13000
13500
14000
14500
15000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig. 3. N2O emissions (t/y) from Natural sources for the period 2000-2012

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0
1000
2000
3000
4000
5000
6000
7000
8000
9000
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 4 N2O emissions (t/y) from Electrical and thermal energy production and public sector heating for the period 2000-2012
0
100
200
300
400
500
600
700
800
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 5 N2O emissions (t/y) from Solid waste treatment and storage for the period 2000-2012

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0
100
200
300
400
500
600
700
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 6 N2O emissions (t/y) from Road transport for the period 2000-2012
0
20
40
60
80
100
120
140
160
180
200
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 7 N2O emissions (t/y) from Industrial processes for the period 2000-2012

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0
20
40
60
80
100
120
140
160
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 8 N2O emissions (t/y) from Communal heating for the period 2000-2012
0
5
10
15
20
25
30
35
40
45
50
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012
Fig 9 N2O emissions (t/y) from Other transport for the period 2000-2012
Data analysis indicates that the major increase trend is
registered in the Agriculture sector (Fig. 2) – from 5200 tons
in 2000 to 27696 tons in 2009 and a slight decrease of
annual N2O emissions afterwards – 24607 tons in 2010,
23555 tons in 2011 and 23765 tons in 2012. Relatively
constant yet high are the levels of N2O emissions from
Natural sources (Fig. 3) – from 13330 tons in 2000 to 14722
tons in 2010, 14697 tons in 2011 and 14684 tons in 2012.
The enhanced N2O emissions from agricultural and natural
ecosystems are caused by increasing soil nitrogen contents
due to intensified fertilizer use, agricultural nitrogen fixation
and atmospheric deposition of air pollutants (nitrates or
ammonia) [11-12].

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The power sector includes combustion processes for
electrical and thermal energy production and public sector
heating [13] and gives significant contribution to the overall
annual N2O emissions (Fig. 4) – 5158 tons N2O are
registered in 2000 and with slight fluctuation the emission
level is increasing gradually to 8287 tons in 2011 and 7209
tons in 2012. The sector of Solid waste treatment and
storage takes the next position regarding the overall N2O
emissions for the monitoring period but the opposite trend is
observed (Fig. 5) - N2O emissions are decreasing gradually
from 712 tons in 2000 to 549 tons in 2012 as 547 tons are
registered in 2010. The same trend is observed for the Road
transport sector [14] (Fig. 6) - N2O emissions are decreasing
from 662 tons in 2000 to 243 tons in 2012 which is 2.7 times
lower.
More dynamic fluctuation of annual N2O emissions is
observed for the sector of Industrial processes (Fig. 7). N2O
emission levels in 2001, 2002 and 2003 are lower than the
emission level in 2000 due to economic crisis in Bulgaria
but from 2004 onwards the annual N2O emissions are
increasing gradually up to 194 tons in 2006. After the
enforcement of regulatory mechanisms for integrated
industrial pollution prevention and control N2O emissions
from that sector decrease significantly to 81 tons in 2010,
which is the lowest emission level for the monitoring period,
90 tons in 2011 and 97 tons in 2012.
Relatively constant N2O emission levels are registered for
the Communal heating sector (Fig. 8) – from 96 tons in 2000
to 131 tons in 2010 and 141 tons in 2012. In 2011 a
significant emission drop to 14 tons is registered probably
due to the warm winter season in the region of Southeast
Europe. The lowest annual N2O emission levels for the
monitoring period are registered for the Other transport
sector where a decrease trend is observed – from 48 tons in
2000 to 28 tons in 2012, which is 1.7 times lower (Fig. 9).
Untypically low emission level from that sector is registered
in 2010 – 4 t/y. Such drastic emission drop is probably
accidental.
Data analysis indicate that a very annoying trend is observed
- the overall annual N2O emissions increase from 25333 tons
in 2000 to 46716 tons in 2012, which is 1.8 times higher,
and a peak value of 49364 tons is registered in 2009.
N2O emissions from combustion and industrial processes in
some regions of Bulgaria for the period 2007-2010 [8] are
indicated in Table 1.
Table 1 N2O emissions in the atmosphere from combustion and industrial processes in some regions of Bulgaria, tons
Industrial region 2007 2008 2009 2010
Kremikovtsi 22 17 4
Pernik 109 88 87 93
Plovdiv 0 8 8 8
Dimitrovgrad 256 238 241 199
Stara Zagora 1 1 3 6
Maritsa-Iztok 4543 4670 4379 4783
Burgas 27 24 13 14
Varna 0 6 12 2
Devnya 164 152 103 98
Ruse 92 124 107 73
Svishtov 57 73 77 61
Other 1354 1282 979 1028
Total 6625 6683 6013 6365
Data analysis indicates that major N2O emission levels are
registered in the region of Maritsa-Iztok industrial complex,
where 3 thermal power stations with total nominal capacity
of 2700 MW and lignite coal mines are located [15] on a
small area of 240 km2
. N2O emission levels in that region
are relatively constant for the monitoring period – from
4543 tons in 2007 to 4783 tons in 2010 and most of them
come from combustion processes for thermal power
production.
High N2O emission levels are typical for the region of
Dimitrovgrad, where chemical industrial plants for the
production of mineral fertilizers and cement are located
along with machinery construction companies. A trend for
N2O emission decrease is observed for the region of
Dimitrovgrad – from 256 tons in 2007 to 199 tons in 2010
due to the reduced production capacity of the fertilizer plant.
Lower N2O emission levels are registered in the region of
Devnya, where various industrial plants are concentrated for
the production of mineral fertilizers, synthetic soda ash,
cement, thermal power, polymers and refined sugar. A solid
trend for N2O emission decrease is observed for the
monitoring period for Devnya region – from 164 tons in
2007 to 98 tons in 2010. The main reason for the emission
levels decrease is the implementation of a joint venture

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project for catalytic N2O emission reduction at nitric acid
production by installing an effective non-platinum
secondary catalyst that is decomposing N2O to nitrogen and
oxygen [16-18].
Similar N2O emission levels (average 95 t/y) are registered
for the regions Ruse and Pernik, where power stations are
dominant N2O emission source. A trend for N2O emission
increase is observed for the region of Svishtov, where a
cellulose producing plant is located – from 57 tons in 2007
to 77 tons in 2009 and afterwards an emission drop to 61
tons is registered in 2010. Relatively low N2O emission
levels with a solid decrease trend are typical for the region
of Burgas, where chemical and petrochemical plants are
situated – from 27 tons in 2007 to 14 tons in 2010, which is
almost two times lower. The lowest N2O emission levels are
registered in the region of Stara Zagora, where mainly food
and light industry plants are concentrated – 1 t/y in 2007 and
2008 but during the second half of the monitoring period a
significant increase is registered – 3 tons in 2009 and 6 tons
in 2011.
Presented data indicates that the overall annual N2O
emission level from combustion and industrial processes in
the monitored regions is relatively constant for the
monitoring period and stays above 6000 t/y due to the
enforcement of effective regulatory mechanisms for
pollution prevention and control.
4. CONCLUSION
Limitation of N2O emissions is an essential step towards
global warming prevention [19-20]. The dominant source
sector of N2O emissions in Bulgaria for the period 2000-
2012 is Agriculture. Emissions from agriculture are mainly
caused by soil cultivation (58 %), biological fermentation of
the stockbreeding waste (21.8 %), manure management
(19.3 %), stubble burning (1.7 %), rice production (1.1 %),
dairy production, etc. [9, 21]. In order to reduce N2O
emissions from agriculture with 64.9 % below their 1988
level (as 1988 is a basic year for Bulgaria under the Kyoto
Protocol) for the period 2013-2020 direct measures on the
total cost of 372.3 million BGN are provided including crop
rotation, biological re-cultivation and soil conservation,
extensive pasture stockbreeding, construction of manure
storage facilities and utilisation of crop residues [9]. The
sectors of Electrical and thermal energy production and
Industrial processes are well regulated regarding N2O
emission reduction. Applying measures that are provided for
both sectors for the period 2013-2020 will lead to significant
improvement of the ambient air quality in the regions where
industrial and combustion emission sources are concentrated
– Maritsa-Iztok, Dimitrovgrad and Devnya. For the power
sector measures are provided for 40 % reduction of
greenhouse gas emissions [9] along with stimulating the use
of low emission technologies and fuels and reducing the
carbon intensity in the energy mix. A priority target for the
industrial sector is to reduce greenhouse gas emissions with
70 % for the period 2013-2020 by enforcing restrictions
during the third period of the European Union Emission
Trading Scheme and by stimulating the industrial use of
alternative fuels. For the transport sector the observed solid
trend for N2O emission decrease need to be continued as
measures are provided for road infrastructure rehabilitation
and modernisation, fuel consumption reduction and haulage
diversification. In order to combat the adverse changes of
the climate system the European Union and its Member
States including Bulgaria have committed to reduce the
overall greenhouse gas emissions by at least 20 % below
1990 levels by 2020 and by 30 % provided that other carbon
intensive economics like USA, China, Brazil, India commit
themselves to comparable emission reductions.
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