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The energy efficiency of domesticpassenger shipping in GreeceErnestos Tzannatosa & Stratos Papadimitrioua

a Department of Maritime Studies, University of Piraeus, Gr.Lambraki 21 & Distomou, 185 33 Piraeus, GreecePublished online: 03 May 2013.

To cite this article: Ernestos Tzannatos & Stratos Papadimitriou (2013) The energy efficiency ofdomestic passenger shipping in Greece, Maritime Policy & Management: The flagship journal ofinternational shipping and port research, 40:6, 574-587, DOI: 10.1080/03088839.2013.779040

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The energy efficiency of domestic passenger shippingin Greece

ERNESTOS TZANNATOS* and STRATOS PAPADIMITRIOU

Department of Maritime Studies, University of Piraeus, Gr. Lambraki 21 &Distomou, 185 33 Piraeus, Greece

By virtue of its coastal and insular character, Greece undoubtedly holds a leadingposition in Europe with regard to domestic passenger shipping. In the quest to improveeconomic competitiveness and curb carbon emissions in Greece, the energy efficiencyand carbon footprint assessment of domestic passenger shipping has so far attractedlittle attention in comparison to other energy consumers, including other modes oftransport. In the current work, energy and carbon efficiency of domestic passengershipping in Greece during the decade 2001–10 is expressed and estimated through theassociated intensity terms, i.e. the consumed energy and carbon dioxide emissions perunit of transport work performed. The energy and carbon efficiency assessment isfacilitated through comparisons with relevant shipping operations in Europe and otherregions of the world. Furthermore, the influence of the market’s seasonal and spatialcharacteristics is also examined. Finally, the analysis of energy efficiency provides themeans for assessing the influence of fuel expenditure upon the overall cost of thesupplied services.

1. IntroductionEnergy consumption and produced greenhouse gas (GHG) emissions in shipping dom-inate the current maritime policy agenda towards the control of climate change, beingmainly based upon the Second IMO GHG Study carried out by Buhaug et al. (2009).According to this most comprehensive study and authoritative assessment of GHGs fromshipping, it was estimated that shipping emitted 1046 million tons of CO2 in 2007, whichcorresponded to 3.3% of all anthropogenic emissions. The CO2 inventory for globaldomestic shipping was estimated at 176 million tons, or about 17% of all ship-relatedCO2 emissions. Due to its significant share and regulatory absence, GHG emissions ofinternational shipping have attracted most attention. However, the energy use of domesticshipping (and particularly that of passenger service) is not only important with regard toclimate change but, being a less demand-driven market than its international freightcounterpart, it has a major effect on its commercial sustainability too.

Domestic passenger shipping in Greece constitutes a complex network of mainland-to-island, island-to-island and mainland-to-mainland connections, along a combined main-land and island coastline which stretches over a length of nearly 15 000 km (being secondto Norway in Europe and 11th worldwide) and distributed at a ratio of 60:40, respectively.Furthermore, 33% of Greece’s population resides within 1–2 km from the coastline,whereas the population living at maximum 50 km from the shore is estimated at 85%.Amongst the 3500 Greek islands and islets, 131 are inhabited and accommodate about

*To whom correspondence should be addressed. E-mail: et@unipi.g

© 2013 Taylor & Francis

Maritime Policy & Management, 2013Vol. 40, No. 6, 574–587, http://dx.doi.org/10.1080/03088839.2013.779040

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15% of the country’s population, although only about half are officially consideredeconomically important (EC 2011a; HME 2006).

Greek domestic shipping has been historically instrumental in the effort to maintainnational cohesion and ensure balanced economic growth and social prosperity (Lekakouand Fafaliou 2003). However, persisting problems and difficulties documented throughrelevant research have hindered its potential in meeting this objective fully (Chlomoudiset al. 2007; Giannopoulos and Aifandopoulou-Klimis 2004; Lekakou 2007; Psaraftis andPapanikolaou 1992; Sturmey et al. 1994). Amongst them, the seasonality of transportdemand in conjunction with a state-dictated obligation for operators to provide an almostinflexible supply of services throughout the year and/or to combine destinations of lowand high commercial interest on a specified line. Therefore, the overall capacity utilisationis low, ranging between 50% and 60% for long distance lines, to 30–35% for mediumdistance lines (where most high-speed vessels operate) and even lower load factors forshorter or very low demand lines. Furthermore, lines or connections of no commercialinterest fall under the public service obligation/public service contract (PSO/PSC) schemeand are awarded through a public tender to the lowest bidder (Chlomoudis et al. 2011).Whether commercial or subsidised lines, a maximum fare for economy class passengers isset by the state, taking into account anticipated fuel expenditure for any given line’sdistance and ship’s speed category. Following this approach, the influence of high fuelprices has often rendered some routes as loss-making, whereas most recently the combi-nation of declining transport demand and spiralling fuel expenditure has led to marketlosses totalling almost half a billion euros in 2011, as reported in a Kathimerini articletitled ‘Ministry shoring up ferry services to Greek islands’, which was published on 14December 2011.

Domestic passenger shipping is provided by around 300 passenger and Ro-Pax vesselsof various types (e.g. open or close deck), sizes, service speeds and age ranging fromnewbuildings to 35 years old, which operate in numerous coastal and ferry lines(Tzannatos 2005). The former lines offer successive calls to different ports per itineraryand the latter provide a single connection between two ports only (as shown in Figure 1).In total, all lines provide around 1500 connections between 42 and 96 mainland and islandports, respectively (Chlomoudis et al. 2007; Psaraftis 1992; Tzannatos 2005). During thedecade 2001–10, the overall annual transport demand peaked in 2003–04. With thisperformance, domestic passenger shipping in Greece ranks as the highest in Europe(EC 2011b) and one of the highest in the world.

According to EU transport statistics, in 2008, domestic shipping in Greece averaged7% of the overall energy used (in Mtoe) for all domestic transport, against an EU-27average of 2% (EC 2011b). With this share, Greece held the top position amongst the EU-27 member states. With regard to Europe, energy consumption of domestic shipping inGreece is only second to that of Norway with a share of 15.5% of all domestic transport.In absolute terms, in 2008, Greek domestic shipping presented the fourth highest con-sumption in the EU-27 with 0.6 Mtoe. Furthermore, in 2008, carbon emissions ofdomestic shipping in Greece reached 1.9 MtCO2e occupying fifth position amongst EU-27. However, its share in total domestic transport is again the highest with 8% against anEU-27 average of 2%. Apart from the importance of energy consumption in terms ofdefining the transport cost structure, within the framework of UNFCCC Greece as anAnnex I country mandated to meet the Kyoto Protocol binding targets for the reduction ofdomestic (national) CO2 emissions. It is important to be able to control carbon emissions

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produced by domestic shipping along the lines of action usually adopted for other energyconsumers. A prerequisite for control is the analytical estimation of ship exhaust emissioninventories, whether at national (Tzannatos 2010a) or at local level (Tzannatos 2010b,2010c).

In view of the aforementioned significance of domestic shipping in Greece, currentresearch acknowledges that in order to arrive at a concrete assessment of energy and carbonefficiency for economy and climate change purposes, it is necessary to proceed with thetemporal and spatial analysis of transport work performed and the associated energyconsumption over a time span capable of capturing the influence of significant factors.

Similar research focussing on a combined analysis of transport work of passengershipping and associated energy consumption and carbon emissions at a national-widescale for a lengthy time period is not available. However, previous related researchprovides valuable information towards drawing indirect and direct comparisons of energyand carbon efficiency for domestic passenger shipping in Greece and elsewhere. Morespecifically, according to the study conducted by best foot forward (BFF) for thePassenger Shipping Association (PSA-UK) carried out in 2007–08, an average emissionintensity of 0.115 kg-CO2/p-km was quoted for a large Ro-Pax vessel, based on ferryservice operator’s experience (BFF 2007). These data are included in the ‘2011 Guidelinesto Defra/DECC’s GHG Conversion Factors for Company Reporting’ as presented in the

Figure 1. Domestic passenger shipping network in Greece.

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website http://www.defra.gov.uk/publications/2011/09/01/ghg-conversion-factors-report-ing/ (Annex 6, Table 6k, page 23), with the note that it does not include any data forpassenger-only ferry services which would be expected to have significantly higheremission. Also, in 2007, M.J. Bradley & Associates carried out a study on behalf of theAmerican Bus Association comparing energy use and carbon emission of differentpassenger transportation modes (Bradley & Associates 2007). The results indicate anaverage energy intensity of 7.2 MJ/p-km and an average emission intensity of 0.51 kg-CO2/p-km, for 57 passengers and Ro-Pax ferries (exc. intercity vessels) operated by seventransport agencies. Furthermore, according to the European Environment Agency (EEA),in 2010, the average emission intensity of the passenger maritime mode for EU-30 (EU-27plus Norway, Switzerland and Turkey) was found to be equal to 0.043 kg-CO2/p-km(EEA 2011).

Most relevant to the current work are the results of the LIPASTO/MEERI system,developed by the VTT Technical Research Centre of Finland and used for the calculationof waterborne traffic emissions and energy consumption in Finland. This system makesreference to a number of specific cases of ferry and Ro-Pax connections between Finlandand neighbouring countries (Makela 2009). The energy intensity ranges between 5.9 and2.7 MJ/p-km, whereas carbon intensity varies between 0.452 and 0.205 kg-CO2/p-km, forhigh- and low-speed vessels with a passenger load factor of 35–50%.

Finally, the COMPASS EU project within its framework of research on the overallcompetitiveness of waterborne transport in Europe included the analysis of the cost structureof Ro-Pax vessels operating in selected routes around Europe (TML and NECL 2010). Forsmall and large vessels, the fuel share varied from 10% to 22% of the total cost, respectively(in 2005 prices). For this year, this result provides the basis for a comparative assessment ofavailable profit margins of domestic passenger shipping in Greece.

Although the variation of operating conditions (particularly with regard to weather) indifferent regions around the world affects the energy consumption of ships, the need forcommercially and environmentally sustainable shipping is universal. Therefore, the detec-tion of differences in energy and carbon intensity between passenger shipping in Greeceand elsewhere has the potential to facilitate the unveiling of controllable factors capable ofimproving the system’s efficiency.

2. MethodologyThe proposed assessment of energy and carbon efficiency of domestic passenger shippingin Greece was based upon the estimation of transport work and the fuel used by thepassenger and Ro-Pax fleet in performing this work, during the last decade (2001–10).

2.1. Transport workThe transport work performed is the product of the number of transported passengers andvehicles and their distance of travel. The applied methodology for estimating the transportwork performed depends on the basic structure of the domestic passenger shippingnetwork and the data of transport demand listed by the Hellenic Statistical Authorityin its website http://www.statistics.gr/portal/page/portal/ESYE/PAGE-themes?p_param=A1103&r_param=SMA06&y_param=2007_00&mytabs=0.

This information is subsequently adapted to suit the needs of the current work. Thenetwork is currently arranged into 12 main coastal and 15 main ferry service lines

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according to distinct geographical regions, which present up to 90% and 95% of the totaltransport demand in passengers and vehicles, respectively. The remaining demandinvolves ‘secondary’ lines (local and/or subsidised), which provide life-line services tonumerous destinations.

The Aegean Sea hosts the overwhelming majority of services, i.e. 11 and 9 of the 12and 15 main coastal and ferry lines, respectively. The Aegean network has a mono-hubstructure centred at the Port of Piraeus, from where 10 (out of the 12) main coastal linesradiate towards the various island regions of the Aegean (Figure 2).

The Hellenic Statistical Authority reports the overall number of transported passengersand vehicles for each of the main ferry and coastal lines and ‘secondary’ lines groupedtogether, on a quarterly and annual basis. For every port in Greece, the quarterly andannual movements (embarkation/disembarkation) of passengers and vehicles are reported.

For ferry lines, the distance over which passengers and vehicles were transportedcoincides with the sailing distance between the two connecting ports, whereas thedistance applicable to the group of the ‘secondary’ ferry lines (of unknown connec-tions) was assumed to be equal to the average distance of the main lines. The distancesof the main ferry lines ranged between 1.8 and 35.2 km, whereas that assigned to thegroup of ‘secondary’ lines averaged a distance of 13.3 km. The performed transportwork along each ferry line is found by multiplying transport demand and the traveldistance per line.

For coastal lines (involving successive port calls), there is no statistical O/D informa-tion available for the internal movements of passengers and vehicles along any given line.Therefore, a demand-weighed trip distance for passengers or vehicles was estimated forevery year and each of the 12 main coastal lines according to the following expression:

1. Argosaronic2. Piraeus–Peloponnese

4. Piraeus–Crete–Dodecanese5. Piraeus–Dodecanese6. Piraeus–West Cyclades7. Piraeus–East Cyclades8. Piraeus–Mykonos–Tinos–Samos

Greece12

10

9

811

76

3

4

5

1

2

Ionian Sea

AegeanSea

Piraeus

9. Piraeus–Chios–Mytilini10. Patra–Ionian Islands11. Rafina–Evoia–Andros–Tinos12. Volos–North Sporades–Kymi

3. Piraeus–Crete

Figure 2. Main regional lines of coastal passenger shipping in Greece.

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S ¼ 1� fð Þ �Pni¼1

m� sð ÞiPni¼1

mi

2664

3775

where S is the average passenger or vehicles trip distance, f is the internal movementfactor, i is the port identification number (i = 1 to n), m is the embarked and disembarkedpassengers or vehicles at port ’i’ and s is the sailing distance between start of line andport ’i’.

The internal movement factor (f) accounts for the percentage movement of embarkingor disembarking passengers and vehicles from or to intermediate ports along any givencoastal line. In Greece, this movement of passengers and vehicles is limited, sincetransport demand is dominantly derived from the islanders’ socio-economic needs tomove back and forth an urban centre (such as Piraeus) and the tourists’ needs to visit asingle-island resort over a short period of time. Although island hopping is popularamongst some (particular foreign) tourists, its influence on the overall picture is verylimited. According to a major operator’s estimates, the annually averaged internal move-ment along the main coastal lines ranges from 0% (f = 0) to 8% (f = 0.08) of the totaltransport demand (personal communication with Blue Star Ferries commercial depart-ment, 8 August 2012). Most internal movement is observed along the multi-port-callingand tourism-attractive lines such as Piraeus–Cyclades and Piraeus–Dodecanese, whereasthe coastal lines of Piraeus–Crete have no internal movement because they provide asingle connection service (i.e. Piraeus–Chania and Piraeus–Iraklio). The annually averageinternal movement for all main lines stands at 5% of their total transport demand (f = 0.05)and this is the value assigned to the internal movement of all ‘secondary’ coastal lines.These estimates of internal movement along the coastal lines were assumed to be equallyapplicable for passengers and vehicles during 2001–10. Therefore, depending on the lineand its annual demand, the trip distance (S) of the main coastal lines ranged between 47.2and 607.6 km, whereas that of the ‘secondary’ line group averaged a length between250.3 and 277.4 km.

2.2. Energy consumption and carbon emissionsThe data of energy consumption for domestic passenger and Ro-Pax ships were basedupon records of fuel sales (in tons of heavy fuel oil and diesel oil) for domestic shippingin Greece, as reported to the UNFCCC and listed in its website http://unfccc.int/national_reports/annex_i_ghg_inventories/national_inventories_submissions/items/5888.php.It is, however, important to note that the reported fuel consumption data relate to theoverall domestic shipping in Greece, which besides passenger and Ro-Pax operationsincludes those of domestic cargo vessels (coasters) and Ro-Ro, as well as fishing andleisure boats. To isolate the fuel consumption of domestic passenger shipping, it wasnecessary to utilise the sales records of three major bunkering companies in Greece.Therefore, for the period 2001–10, a fuel market factor (fM) ranging from 0.61 to 0.82 wasobtained, which represents the annual share of heavy fuel and diesel oil sales for domesticpassenger shipping in relation to the overall domestic market (personal communicationwith EKO, AVIN and AMPNI sales departments, 24 April 2012).

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Given that propulsion energy (fuel) consumption is proportional to the cube of ship’sspeed, the figures of the main propulsion fuel (HFO) were adjusted by a speed factor (fS)to account for annual speed variations. The average fleet’s speed varied from 16.7 to 17.4knots annually, whereas the fuel-weighted speed of the fleet averaged 17.1 knots during2001–10. For every year, the speed factor (fS) is given by following expression:

fS ¼ VAV

V

� �3

where fS is the speed factor, VAV is the fuel-weighted speed of the fleet during 2001–10,equal to 17.1 knots, and V is the average fleet’s speed.According to the aforementioned adjustments on fuel sales figures for the overall domesticshipping market in Greece, the annual fuel consumption of heavy fuel and diesel oil fordomestic passenger shipping is given by the expressions:

FF ¼ SF � fM � fS

FD ¼ SD � fM

where FF is the consumption of heavy fuel oil, FD is the consumption of diesel oil, SF isthe sales of heavy fuel oil, SD is the sales of diesel oil, fM is the fuel market factor (heavyfuel and diesel oil) and fS is the speed factor (heavy fuel oil).

The average unit cost of heavy fuel and diesel oil (UFC) in Piraeus during 2001–10was compiled using the Bunkerworld website http://www.bunkerworld.com/prices/ (withthe adoption of the appropriate currency exchange rates according to the ECB data listedin www.ecb.int/stats/exchange/eurofxref/html/index.en.html). Finally, with regard to theenergy content (net calorific value, NCV) and carbon emission factors (CEFs) for marineheavy fuel and diesel oil, the relevant data as reported to UNFCCC by Greece were againemployed. The above-mentioned fuel- and price-related information is presented inTable 1.

Table 1. Energy-related information for domestic passenger shipping in Greece.

Fuel sales factor and fuel prices

Year 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

fM 0.61 0.62 0.62 0.62 0.65 0.67 0.68 0.75 0.81 0.82fS (for HFO) 1.07 1.03 1.05 1.03 0.99 0.99 0.99 0.96 0.94 0.94$/€ 1.12 1.06 0.89 0.80 0.80 0.80 0.73 0.68 0.72 0.75UFC(€/ton)

HFO 134 143 116 104 184 264 256 340 202 345MDO 235 191 187 168 408 520 456 734 288 510

Fuel energy content and carbon emission factor

Fuel type NCV (TJ/fuel ton) CEF (CO2 ton/fuel ton)

HFO 40 190 3.15MDO 43 000 3.08

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3. Results and discussion3.1. Transport demandDuring 2001–10, the total annual passenger and vehicle demand were on an average equalto 46.7 and 12.4 million, respectively. In general, the strong correlation between passengerand vehicle transport demand, first reported by Psaraftis and Papanikolaou (1992), ismaintained (Figure 3).

On an average, the movement of passengers and vehicles via ferry lines represented64.6% and 77.4% of the overall transport demand, respectively. This is mainly attributedto the high-demand commuting services offered by some ferries (e.g. the connection ofPaloukia–Perama with an annual average of 12.3 and 4.2 million passengers and vehicles,respectively). Prior to 2004, demand for ferry services was also high due to the connectionoffered by open-deck ferries at Rio-Antirrio. In 2005, the bridge connection brought asudden drop in the demand of ferry passengers and vehicles of around 8 and 1.5 million,respectively, which was partially recovered by an increase in demand during 2006–07. Onthe contrary, coastal line services followed an overall trend of increasing transport demandof passengers and vehicles up to 2007. Finally, during the post-2007 period, the impact ofthe recent economic crisis brought a noticeable decline of transport demand in both typesof lines and transportable.

During 2001–10, the main coastal lines accounted for 85–90% of the total coastalpassenger movements, whereas the main ferry ones covered 90–95% of the total ferrypassenger demand. Over the same period, around 88% of the overall passenger or vehicletransport demand was served through the Aegean network. More analytically, the Aegeanaccommodated an average of 97.3% and 96.0% of the coastal transport of passengers andvehicles, respectively, whereas the corresponding values for ferries in this region were78.7% and 80.4%. Coastal passenger transport demand within the Aegean is further splitinto Cyclades by 33.3%, Argosaronic by 16.5%, Crete by 15.2%, Dodecanese by 5.8%and the north Aegean by 4.4%.

0

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2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

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× 1

06)

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nsp

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Ferry passengers Coastal passengers Total passengers

Ferry vehicles Coastal vehicles Total vehicles

Figure 3. Passenger and vehicle transport demand in coastal and ferry lines.

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Furthermore, transport demand was found to be highly seasonal with the ratio of high(2nd and 3rd quarters) to low (1st and 4th quarters) season being on an average equal to2.31:1 and 2.13:1 for passengers and vehicles, respectively. The seasonality of transportdemand is higher in the coastal lines than their ferry counterparts, namely 2.8:1 versus1.6:1, respectively. This is mainly because the coastal lines serve the numerous islanddestinations of the Aegean, which are more popular for summer holidays. Besides theabove-mentioned comparison between coastal and ferry services, a similar argument isvalid within the coastal shipping market as destinations of tourist interest (e.g. Cyclades)present a higher seasonality in comparison to others, which combine business and leisure(e.g. Crete). In conclusion, there are significant spatial variations in the qualitative andquantitative characteristics of transport demand, depending upon the characteristics of thedestination (e.g. urbanised islands vs. rural island communities). Finally, it is important tomention that the seasonality of demand has been recently reduced at an annual rate of17.4% mainly due to the decline of transport demand for tourist purposes as a conse-quence of the post-2007 economic crisis.

3.2. Transport workThe total passenger and vehicle transport work peaked in 2006 (Table 2). As expected,major contribution came from the coastal lines, because despite their comparatively lowertransport demand they involve the movement of passengers and vehicles over significantlylonger distances. The transport work of the ferry lines constituted on an average only 5%and 8% of the total passenger and vehicle transport work performed, respectively.

During 2001–10, the distance covered by transported passengers and vehicles throughthe coastal lines averaged 242.4 and 251.9 km, respectively. For the ferry lines, thecorresponding distance was found to be 8.4 and 8.0 km, respectively.

Also, comparing Figures 3 and 4, the increase of the passenger transport workperformed by the coastal lines during 2003–06 is disproportionally higher than theincrease in the passenger transport demand over this period. This is attributed to thesimultaneous increase in the distance covered by the transported passengers. Morespecifically, the annual average distance travelled by coastal passengers increased from230.3 km in 2003 to 249.3 km in 2006.

Again, due to the limited influence of ferry services, the overall transport work post-2007 follows the pattern of the drop in overall transport demand and mainly thatassociated with the coastal shipping services.

Table 2. Transport work performance by domestic passenger shipping in Greece.

Transport work (×106)

Year

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Ferry p-km 247 256 250 246 216 223 241 235 230 222Ferry v-km 69 72 82 76 72 73 79 77 77 70Coastal p-km 3484 3391 3433 4118 4355 4695 4343 4287 4090 4080Coastal v-km 611 618 612 754 751 793 785 775 749 732Total p-km 3731 3647 3683 4364 4571 4918 4584 4521 4321 4302Total v-km 681 690 693 830 823 866 864 852 825 802

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3.3. Energy consumption and carbon emissionsFuel consumed by domestic passenger shipping totalled an annual average of 428 000tons throughout 2001–10 and ranged from 385 000 to 479 000 tons annually. Utilising thedata presented in Table 2, with regard to the energy content (NCV) and carbon emissionfactors of heavy fuel and diesel oil, the annual energy consumption and the carbonfootprint (emitted CO2) of domestic passenger shipping for the period 2001–10 isshown in Figure 5. Overall, during 2001–10, the energy consumed and carbon emittedby domestic passenger shipping in Greece increased with strong correlation, because theconsumption of heavy fuel and diesel oil followed a similar pattern and the differences in

0

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asta

l tra

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ork

(×1

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Coastal p-km Coastal v-km Ferry p-km Ferry v-km

Figure 4. Passenger and vehicle transport work performed in coastal and ferry lines.

1.0

1.1

1.2

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15 000

16 000

17 000

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2001 2002 2003 2004 2005 2006 2007 2008 2009 2010

Em

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O2

(to

ns ×

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Co

nsu

me

d e

ne

rg

y (

TJ)

Year

Consumed energy Emitted CO2

Figure 5. Consumed energy and emitted carbon by domestic passenger shipping.

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energy content and emission factors for the two types of fuel are limited. Both energyconsumption and carbon emissions peaked in 2006.

For 2008, the emitted CO2 was estimated at 1.49 million tons, which represents 78.4%of the 1.9 million tons reported for all domestic navigation in Greece (EC 2011b).Therefore, the remaining 21.6% is associated with all the other domestic shipping opera-tions, such as fishing and leisure.

3.4. Energy and carbon intensity and efficiencyDuring 2001–10, the annual energy intensity averaged 4.2 MJ/p-km and 22.6 MJ/v-km,whereas the annual carbon intensity averaged 0.31 kg-CO2/p-km and 1.69 kg-CO2/v-km.As expected, the strong correlation between energy and carbon intensities follows that ofenergy consumption and carbon emission, as mentioned in Section 3.3 (Figure 6).

The lower energy and carbon intensity values indicate more efficient operation. Theminimum energy and carbon intensities occurred in 2005 and were estimated to be equalto 3.9 MJ/p-km and 0.29 kg-CO2/p-km, respectively. This was, also, a clear turning pointover the 2001–10 decade, because the continuous rapid drop of energy and carbonintensities observed prior to 2005 period was followed by a continuous steady increaseduring the post-2005 period. The low energy (and carbon) intensity values for 2004 and2005 reflect improved utilisation of the supplied capacity, because (with reference toFigures 4 and 5) the increase in transport work was higher than the increase of the energyconsumed during this period. The assessment of energy and carbon efficiency is basedupon comparison with relevant data available by other similar studies, as shown inTable 3.

The results of the current analysis are closest to those by Makela (2009), which areassociated with the services of specific Ro-Pax and ferries operating in the Gulf ofFinland. These ships are similar to a number of ships operating in the Greek seas undercomparable utilisation (load) factors. The lower and upper values of energy and carbonefficiency of the Greek ships fall well within the range of their Finish counterparts. The

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Figure 6. Energy and carbon intensity of domestic passenger shipping.

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case studied by Bradley & Associates (2007) presents a highly inefficient operation inboth energy and carbon terms, due to the presence of many high-speed crafts, such ashovercrafts and hydrofoils. Finally, the very low carbon intensity quoted by BFF (2007) isattributed to the absence of passenger-only ferries, whereas the extremely low valuepresented by EEA (2011) is considered to be the least suitable for comparison becauseit refers to maritime operations in general.

With regard to the annually averaged fuel cost intensity, an overall increasing trend wasobserved. With an average value of 0.029 euro/p-km throughout 2001–10, the lowest andhighest values occurred in 2004 and 2008 with 0.014 and 0.052 euro/p-km, respectively(Figure 7). This represents a fuel cost fluctuation of nearly 4:1, which in the absence ofcomparable changes in energy intensity (maximum to minimum energy intensityratio = 1.2:1, as in Figure 6) reflects the overwhelming influence of changes in bunkerprices.

Indeed, extended periods of high bunker prices have often led to the accumulation ofsignificant economic losses for the shipping operators, as fare pricing cannot follow thesharp changes in bunker prices. As an example, in 2008, the economy class passenger farealong the Piraeus to Iraklio (Crete) line was priced at 34 euro, when on the basis of the

Table 3. Comparison of energy and carbon efficiency studies for passenger shipping.

Source of study MJ/p-km Kg-CO2/p-km

This study 3.9–4.8 (4.2)* 0.29–0.36 (0.31)*BFF (2007) — 0.115Bradley & Associates (2007) 7.2 0.51EEA (2011) — 0.043Makela (2009) 2.7–5.9 0.205–0.452

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estimated fuel cost intensity value for 2008 the associated fuel cost for this trip of 324 kmis 17.2 euro, i.e. around 50% of the fare’s price.

According to the most recent industry report listed in XTRC website http://www.xrtc.gr, the fuel cost contribution to the total operating costs of the coastal and ferry shippingmarket in Greece peaked with 49% in 2008. It is also shown that following a drop to 44%in 2009, the fuel cost share rose to 48% in 2010. This reported trend is in agreement withthe observed fuel cost intensity values shown in Figure 7. Although operators’ revenuesrely also on income from higher-class passenger fares and cabins as well as that fromvehicles, there can be little doubt that such a high share of fuel cost in the overall coststructure may endanger operators’ balance sheets.

4. ConclusionsDomestic passenger shipping in Greece is organised through an extensive network ofcoastal and ferry lines, which supports a significant transport demand of passengers andvehicles through the employment of numerous Ro-Pax and passenger vessels. It wasfound that the estimated carbon footprint of the sector constitutes a reliable analysistowards the national submission to UNFCCC for all domestic shipping operations.

Against the background of a state-dictated adherence to an almost inflexible supply ofservices throughout the year, the high seasonality in demand is the main contributor tolow capacity utilisation (load factors). Nevertheless, the sector’s estimated energy andcarbon efficiencies for the decade 2001–10 are comparable to those quoted by otherrelevant studies for similar operations elsewhere in Europe and internationally.

Since low capacity utilisation in conjunction with high bunker prices is alreadythreatening the sustainability of services, a shift towards a policy that promotes the socialcohesion doctrine with more due consideration to market issues, such as allowing flex-ibility in supply to match transport demand and relaxing fare pricing policies to matchbunkering costs, may prove to be a necessary move for the future.

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