International Journal
on Marine Navigation
and Safety of Sea Transportation
Volume 2
Number 4
December 2008
405
The Implementation of Oil Spill Costs Model in
the Southern Baltic Sea Area to Assess the
Possible Losses Due to Ships Collisions
L. Gucma & E. Goryczko
Maritime University of Szczecin, Szczecin, Poland
ABSTRACT: The paper presents an attempt to assessment of losses due to oil spills caused by ships collisions
in the Southern Baltic Sea area. To assess the losses the data from two models were used. First of them is
simulation model of ships collision with consideration of oil spills developed and the second is the model of
oil spill cleanup cost is applied without consideration of environmental conditions influence.
1 INTRODUCTION
The safety of large engineering systems can be
evaluated by simulation models. In engineering
practice the cost of accidents is the most important
factor in decision making process and risk analysis.
There are two typical engineering systems in
consideration of accident consequence assessment:
1. involving human fatalities, and 2. not involving
human fatalities. In the second kind of the system
pure economical analysis of consequences can be
carried out. In case of ships accident in the open sea
the fatalities could not be neglected but due to the
subject of the paper which is the oils spills
probability the possible human fatalities are outside
of interest of studies carried out.
Complete model of oil spill cost model was
presented in previous works of the Authors
[Goryczko & Gucma 2006] where the losses to
environment expressed by Life Quality Index was
presented.
2 THE COST OF OIL SPILLS
On the basis of statistical analysis of 96 oil spills the
correlation with spill size have been found. The cost
of small oil spills are at least 20-times higher than
big ones [Etkin 2000, 2001].
Independent of size and extend of oil spill every
time the proper monitoring full mobilisation of
resources and human and equipment which leads to
high cost. The Fig. 1 presents correlation between
spill size and its cleanup costs in different size group
of oil spills. To find the model the exponential
model is used (Fig. 2). The cleanup cost are high due
to constant fraction not dependant of spill size costs.
The model can be written as [Goryczko & Gucma
2006]:
04184
255218
−
= vC
(1)
where: C = cost of oil cleanup in zloty; v = the
amount of oil spill [t].
241477,6
96208,5
33129,7
30246,7
19809
11426,6
7337,7
1106,7
0
50000
100000
150000
200000
250000
300000
0,34-3,40 3,4-17,0 17-34 34-340 340-1700 1700-
3400
3400-
34000
>34000
Cost of cleanup [zł/ton]
Fig. 1. Correlation of oil spill size with its cleanup cost
406
y = 255218x
-0,4184
R
2
= 0,9243
0
20000
40000
60000
80000
100000
120000
140000
160000
180000
200000
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
22000
24000
26000
28000
30000
Spill size [ton]
Cleanup cost [zł/ton]
Fig. 2. Theoretical model of oil sill up costs by exponential
function
3 STOCHASTIC MODEL OF SHIPS
ACCIDENTS
One of the most appropriate approach to assess the
safety of complex marine traffic engineering systems
is use of stochastic simulation models [Gucma &
Przywarty 2007]. The model presented on Figure 3
could be used for almost all navigational accidents
assessment like collisions, groundings, collision with
fixed object [Gucma & Przywarty 2007], indirect
accidents such as anchor accidents or accidents
caused by ship generated waves [Gucma &
Przywarty 2007]. The model could comprise several
modules responsible for different navigational
accidents. In presented studies the model was used to
assess the probability of oil spills in the Baltic Sea
area.
Fig. 3. Diagram of fully developed stochastic model of
navigation safety assessment
The simulation results with consideration of
collision are presented in Fig, 4. The results are
according to expectations – most collision are taken
place on the most highest according to ships density
places. The assumptions and input data of simulation
are presented in Table 1.
5900000
6000000
6100000
6200000
6300000
6400000
200000 300000 400000 500000 600000 700000 800000 900000 1000000
3877 years
Fig. 4. The results achieved by simulation model (places of
ship’s collisions) [Gucma & Przywarty 2007]
4 RESULTS – CLEANUP COST
The simulation model results are presented in Table
1. The time between collision are very similar to real
data for the Southern Baltic Sea (2-3 collision per
year) but the oil spills could not be verified due to
small sample of real accidents.
Table 1. Simulation assumptions and its results
Time of simulation [years]
3877
Number of collisions
9036
Number of collisions with oil spills
1406
% of oil spills in collisions
0.15
Number of collisions per year
2.33
Number of oil spill per year
0.36
Time between collisions [years]
0.43
Time between oil spills [years]
2.76
Mean oil spill [t]
2091
To find the yearly cost of oil spills the size of
given oil spill expressed in v
i
are divided by the
simulation time T and multiplied by cost of cleanup
c
i
of oil spill according to formula 1 and number of
oil spills during simulation N
os
:
c
yi
= v
i
c
i
N
os
/T (2)
The results are presented on Figure 5. As it was
expected the highest cost of oil spill is near the
routes of highest traffic of ships. After amendments
in routing the main stream of ships moves near the
South Sweden coast.
The model of cost is simplified and assumes that:
− oil doesn’t move on the water;
− oil doesn’t move to the shore;
− all the oil spilled is cleaned on the open sea.
407
Fig. 5. Mean oil spill cleanup costs in million zloty per year for
ships traffic estimated at 2010 year
4.1 Distribution of simulated spilled oil
Figure 6 presents simulated distribution of oil spill
size. Small oils spills less than 1000 tons are
dominating. The smallest spills are most likely are
result of bunker spill after collision.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 100 500 1000 5000 30000 50000 100000
Spill size [t]
Frequency
Fig. 6. Simulated distribution of oil spill size
4.2 Real oil pollution data
From the other side the historical results from the oil
spill accidents according to Maris accident database
(Fig. 7) are comparable with simulation results.
Fig. 7. The real places of illegal oil discharges on the Southern
Baltic Sea [Helcom 2006]
5 CONCLUSIONS
The paper presents an example of calculating of oil
spill cleanup cost in the Baltic Sea after navigational
collision accidents. The model has several
simplifications and could be used only for early
design purposes. The results of the model are very
close to expectations. The cost of accident removal
is important factor to design marine traffic
engineering systems such as traffic routes or places
of refuge. The cost of removal of accident oil spill is
highly correlated with ships traffic.
It is planned that the oil spill model will be
amended in the future by several factors like:
− complex oil spill behaviour in different
conditions,
− extend of coast pollution,
− outflow rate from damaged ship.
REFERENCES
Etkin D.S. 2001. Comparative methodologies for estimating
on-water response costs for marine oil spills. International
Oil Spill Conference.
Etkin D.S. 2000. Worldwide analysis of oil spill cleanup cost
factors. Proceedings, Twenty-Third Arctic and Marine
Oilspill Program (AMOP) Technical Seminar. Environment
Canada, Ottawa, Ontario.
Goryczko E.
& Gucma, L. 2006. Szacowanie kosztów rozlewów
olejowych (Estimation of oil spill cost), Mat. XV Między-
narodowej Konferencji Rola nawigacji w zabezpieczeniu
działalności ludzkiej na morzu, Gdynia.
Gucma L.
& Przywarty, M. 2007. The model of oil spills due to
ships collisions in Southern Baltic area. 7
th
International
Navigational Symposium on Marine Navigation and Safety
of Sea Transportation TransNav’2007, Gdynia.
Helcom 2006. http://www.helcom.fi