219

1 INTRODUCTION

Compared to other forms of tourism, cruising tourism

is a relatively recent phenomenon. The first cruiser,

the Oceanic, built exclusively for cruises in North

America, was delivered to the Home Lines company

in 1965 and this act is considered the beginning of

modern cruising. Since 1966, the Norwegian

Caribbean Line has been offering a year round cruise

itineraries on the Sunward, the first company in the

world to provide this type of offer. Thus, the 1960s

mark the true beginning of cruising with the first

cruises to the Caribbean for US and Canadian

passengers. From the 1970s on, there has been a

continuous growth of cruises, this trend spreading in

the 1990s first to Europe, primarily the United

Kingdom, and then to the Asia-Pacific region. Cruise

ships today offer a world of innovative facilities and

services that aim to satisfy the expectations of a

growing population of travellers [1].

Rich social and natural tourist resources are highly

valued and recognized by for the cruising industry

[2]. Owing to its natural environment, rich history and

many cultural and historical monuments, Dubrovnik

has reached the very top of the world's tourist

destinations. The beginnings of cruising tourism in

Dubrovnik date back to the 1980s, and today the port

of Dubrovnik occupies an important position

regarding the reception of cruise ships.

Sea cruises have a strong impact on the life and

development of crushing destinations and affect the

social sphere, the economy, and above all the

environment [3]. The article deals with the issue of

cruising tourism in Dubrovnik related to CO

pollution. CO

2 emissions are calculated according to

Emission Inventory of Ships Calling at the Port of

Dubrovnik

A. Zekić, R. Ivče & R. Radonja

University of Rijeka, Rijeka, Croatia

ABSTRACT: Cruising tourism is becoming increasingly popular, the number of cruises having seen a

continuous increase since the 1970s. In Croatia as well there is an upward trend in the number of cruise

passengers and ports. Of all Croatian ports, it is the port of Dubrovnik that has had the most calls by foreign

cruisers. The paper analyses the available statistical data on the maritime cruise market in Europe with special

reference to the Mediterranean countries. In the national context, a presentation of cruise traffic in the port of

Dubrovnik is given. Although this type of tourism contributes to the development and improvement of the

economy, it also has a negative impact on the environment through air pollution by CO

2 emissions,

subsequently affecting human health as well. The authors investigate the level of CO

2 emissions in the area of

the port of Dubrovnik. CO

2 emissions were calculated based on cruiser activity, the calculations being based on

2 emissions for three ship navigation modes - slow steaming on arrival and departure, manoeuvring on

arrival and departure, and for a berthed ship. The aim of the research was to provide a better insight in the

emission inventories in this area. This research can also be applied to other port areas.

http://www.transnav.

the

International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 16

Number 2

June 2022

DOI: 10.12716/1001.16.02.03

220

the activities of cruisers that docked in the port of

Dubrovnik in 2019.

2 CRUISE TOURISM MARKET

Cruising tourism market in Europe is constantly

growing. The cruise sector should generate more than

$ 133 billion in the world. Europe will account for

38.7% of this value [4]. In 2018, European ocean cruise

passenger numbers grew by 3.3 per cent against 2017,

to 7.17million; following a two per cent growth the

prior year [5]. It should be noted that the number of

cruise ports in the Mediterranean has doubled in the

last ten years. Many of these ports are regarded as

"must see" destinations. The Mediterranean is a very

valuable area for tourists, attracting hundreds of

thousands of visitors from all over the world, i.e. the

USA, Japan, China, Germany, France and the Great

Britain and the others [6].

Being part of the Mediterranean region and

boasting a coastline of 6,278 km, Croatia has also

found its place in the cruise market. Its exceptional

natural and cultural resources, numerous tourist

attractions, nature parks and other protected parts of

nature, as well as monuments and a large cultural

offer, provide an excellent basis for the development

of cruising tourism. It is not surprising, therefore, that

the number of cruise calls and passengers in Croatia is

increasingly on the rise. About twenty of its ports are

included in international cruising, ranging in traffic

intensity from the largest of international importance

(Dubrovnik, Split, Zadar, Rijeka), through those of

domestic importance (Pula, Korčula, Mali Lošinj), to

small, local ports such as those on Lopud, Mljet, Šipan

and the like.

In 2018, 693 cruises of foreign ships were realized,

with 1,033,885 cruise passengers who stayed in

Croatia for a total of 1,421 days. Compared to the

previous year, the number of foreign cruise ships

calling at Croatian seaports in 2018 decreased by 8.5%,

the total number of days they stayed in ports

decreased by 5,6%, but the number of passengers

increased by 9.1% [7]. The leading position in cruise

calls is held by the County of Dubrovnik-Neretva,

which together with the County of Split-Dalmatia

accounts for 80.8% of cruise calls, the remaining 19.2%

of cruises having been achieved in other counties. An

overview of realized cruises by counties is given in

Figure 1.

Figure 1. An overview of realized cruises by counties, 2018.

3 THE IMPACTS OF CRUISINF TOURISM ON THE

ENVIRONMENT

The economic effects of cruises for the local and

regional economy are significant, especially when a

port is the place of embarkation/disembarkation of

passengers. Cruising tourism is the driver of

development of many economic activities and is a

source of income for both the private and the public

sectors. However, cruising tourism also brings with it

certain forms of pollution.

Waste discharge; air pollution; bio-security risks;

accidents anchor damage; wildlife and water turbidity

have all been identified as adverse environmental

impacts [8]. Furthermore, it should be noted that the

average daily pollution from a cruiser comprises,

respectively, 40 litres of faeces, 360 litres of

wastewater and 2.3 kg of solid waste per passenger

per day, as well as 60 litres of toxic waste (Photoshop

waste, fluorescent lamps, batteries), 2,800 litres of

bilge water per day, and 1,000 tons of ballast water

changed before entering the port and the exhaust

emissions equivalent to 12,240 cars [9].

Ships are responsible for roughly 3% of global CO

and GHG emissions (CO

2-eq), emitting approximately

1 billion tonnes of CO

2 and GHGs per year [10]. Air

pollution by a ship varies depending on whether the

ship is sailing on the high seas, manoeuvring or is at a

berth in a port. Studies show that in cities like

Vancouver air pollution coming from a ship

contributes to the city’s greenhouse effect with 58%

and participates in sulphur gas emissions with about

95%. Thus, a larger ship arriving in port can emit in

one day as many sulphur oxides (SOx) as 2,000 cars

and trucks in one year [11].

Air pollution by nitrogen, sulphur and carbon

oxides, and suspended particles can have: [12]

− local impact - contribution to smog generation

(30% of global smog comes from ships),

− regional effect - contribution to the creation of acid

rain that destroys the plant world, changes the pH

of stagnant waters and destroys facades and

sculptures of limestone origin,

− global impact - greenhouse gases that cause

climate change (primarily carbon dioxide),

− direct impact on human health - increasing the risk

of lung cancer and asthma.

Additional air pollution refers to pollution from

ship incinerators in which larger cruisers burn most of

the mixed waste, resulting in dioxin and thiophene

emissions [13]. In addition to the direct pollution that

comes from the cruiser itself, there is also indirect

pollution from the cruiser that is at berth related to the

flow of passengers and goods. Buses, trucks, cars and

other modes of transport use the terminal to ensure

the best possible mobility of tourists and the supply of

the ship, which also results in increased CO

emissions. When fossil fuels are combusted, the

carbon stored in them is almost entirely emitted as

2 [14].

Air pollution by CO

2 emissions caused by cruisers

by their navigation regime is shown below on the

example of the port of Gruž in Dubrovnik.

221

4 EMISSION ESTIMATION FOR THE PORT OF

GRUŽ - DUBROVNIK

The emission estimation area has been divided in a

three separate emission category: slow steaming on

arrival and departure, maneuvering on arrival and

departure, and for berthed ship. For mentioned

categories ship's emissions were calculated on the

ship activity-based method. Reduce speed zone is

defined as the distance from the beginning of the end

of sea passage (EOP) point to the commencement of

the maneuvering regime in the port during the arrival

and also on their departure from the end of the

maneuvering regime to full away on passage (FAOP).

Mentioned zone including the pilotage area. For port

of Gruž mentioned distance is approximately 4 M.

The estimated maximum safe speed in the reduced

speed zone is 6 knots for cruise ships calling port of

Gruž in Dubrovnik. In this zone the average speed of

a ship is reduced, but its steaming time to a port is

increased, and that will cause higher emissions.

The ship's machinery plant on cruise ships is a

complex system because it must ensure the ship’s

propulsion and provides electrical power to maintain

all ship's systems in the operation status. The newer

generation of cruiser ships is equipped by diesel

electric plant and gas electric plants. On these ships,

engines are not connected to propeller shafts, and

instead of it they are directly connected to generators

in order to produce electricity for ship's propulsion

system and other consumer on board ship. The older

generations of cruiser ships have most common

machinery plant which is configured of one or two

main engines (rarely more) and two or more auxiliary

engines with a connected generator. Emission

reduction usually combines measures involving the

choice of fuel type, thus improving engine

performance, or special exhausts gas management

[15].

The data for the machinery plant of all cruise ships

called port of Gruž have been obtained from the pilot

company providing pilotage in the mentioned area.

Rating powers of the engines mostly have been taken

from obtained data and for some of them it has been

approximately determined on the gross tonnage basis

[16]. The collected data have shown that most of

cruise ships were equipped by diesel electric

machinery plant.

The assumed average specific fuel consumption of

the newer generation of cruiser ships equipped by

diesel electric plant were about 170 g/kWh and for

older cruiser ships equipped by most common

machinery plant were about 223 g/kWh. The engines

of the cruise ships calling at the port of Gruž consume

low quality fuels (heavy fuel oil) during the steaming

segment and Marine Gas Oil (MGO) during slow

steaming and the manoeuvring segment as per

requirement of EU Directive. The emission factors for

these types of fuel depend on the respective type of

the engine and the ship's activity. The CO

2 emission

factor for the engines installed on the newer

generation of cruiser ships equipped by diesel electric

machinery is 588 g/kWh for slow steaming, 647 g/kWh

for maneuvering and 690 g/kWh for berthed ship.

Cruise ships equipped by gas electric machinery have

following emissions factors: 922 g/kWh for slow

steaming, 1014 g/kWh for maneuvering and same,

1014 g/kWh for berthed ship. The emission factors for

the engines installed on the older cruiser ships are 645

g/kWh for slow steaming and 710 g/kWh for

maneuvering. The auxiliary engines on the older

cruise ships involved in the study consumed about

223 g/kW MGO, and their respective fuel emission

factors was about 690 g/kWh (all the data given in

Table 1).

The Intergovernmental Panel on Climate Change

IPCC) Guidelines provide a general approach to

estimating emissions from the combustion of fossil

fuels for navigation. The basic equation is: [17]

( )

ab ab

Emissions Fuel Consumed Emission Factor= ⋅

∑

(1)

where a presents the fuel type (diesel, gasoline, LPG,

heavy oil, etc.) and b the water-borne navigation type

(i.e., ship or boat, and possibly the engine type). Each

ship emission depends on the time passed in the ship

activities; the ship's power consumption and emission

factors are estimated during the slow steaming and

manoeuvring, and in berthed ship. The data for the

emission factors of the certain CO

2 have been obtained

from the ENTEC ship emissions inventory study [18].

The emissions for the engines installed on the

older cruiser ships were estimated through the

application of the following expressions:

( )

ME ME steam AX AX AX

Em steam P L EF P L EF

V steam

= ⋅ ⋅⋅ +⋅⋅

(2)

( ) ( )

man ME ME man AX AX AX

Em man tm P L EF P L EF= ⋅ ⋅⋅ +⋅⋅

(2)

( ) ( )

berth AX AX AX

Em bething tm P L EF= ⋅ ⋅⋅

(4)

where P

ME is the main engine power (kW), PAX the

power (kW) of auxiliary machines which drive

generators, V is the ship's average speed (steaming or

manoeuvring (Nm/h), D is the distance between

cruising and manoeuvring (Nm), L

ME is the load factor

of the main engine (%), L

AX the load factor of auxiliary

engines which drive generators at steaming,

manoeuvring and berthing (%). EF

Steam is the emission

factor of the main engine in steaming (g/kWh), EF

man is

the emission factor of the main engine in

manoeuvring (g/kWh), EF

AX is the emission factor of

engines which drive generators for steaming,

manoeuvring and berthing (g/kWh). The emissions for

the engines installed on the cruiser ships equipped by

diesel electric and gas electric engine were estimated

through the application of the following expressions:

( )

E E steam

Em steam P L EF

V steam

= ⋅ ⋅⋅

(5)

( ) ( )

man E E man

Em man tm P L EF= ⋅ ⋅⋅

(6)

( ) ( )

berth E E B

Em bething tm P L EF= ⋅ ⋅⋅

(7)

222

where PE is engines power (kW), V is the ship's

average speed (steaming or manoeuvring (Nm/h), D is

the distance between cruising and manoeuvring (Nm),

E is the load factor of the engines (%), EFSteam is the

emission factor of engines in steaming (g/kWh), EF

man

is the emission factor of engines in manoeuvring

(g/kWh), EF

B is the emission factor of engines in port

(g/kWh). Ships' activities, load factors and emission

factors are shown in Table 1.

Table 1. Ships activities, load factor and emission factors.

_______________________________________________

Ship's No Activities Dur Engine Load Emiss

type call (av. time) system f. f.

(h) (%) (g/kWh)

_______________________________________________

Cruise 3 Sl. steam. 0,7 Main E 65 645

ship Aux E 80 690

Common Manouv 1,0 Main E 25 710

machinery Aux E 80 690

plant Berth 18,8 Main E 0 0

Aux E 40 690

Cruise 1 Sl. steam. 0,7 Diesel 70 588

ship eletric

Diesel Manouv 0,9 Diesel 60 647

electric eletric

machinery Berth 10,5 Diesel 50 690

eletric

Cruise 1 Sl. steam. 0,7 Gas 70 922

ship eletric

Gas Manouv 0,9 Gas 60 1014

electric eletric

machinery Berth 9,5 Gas 50 1014

electric

_______________________________________________

5 RESULTS AND DISCUSSION

The total annual CO

2 emission of the cruise ships

calling at the Port of Gruž is approximately 1699 t.

The quantity of CO

2 emission depends on the installed

engines type and its activity (slow steaming,

manoeuvring, and berthing). The older type of cruise

ships also equipped by auxiliary machinery drives

generators which provide electric power to all ship

systems and emit CO

2 during the slow steaming,

manoeuvring and berthing.

Figure 2. Total exhaust emission for all ship's category

calling port of Dubrovnik.

All the ships considered in the study had a great

loading factor during manoeuvring and berthing. The

longest activity for all ship categories is during

berthing (berthed ship). The exhaust gas emissions

according to ship types are specified in Figure 2. The

highest levels of exhaust gas emissions were

generated from cruise ships equipped by diesel

electric plants because of the greater number of ship

calls. The total CO

2 emission for cruise ships equipped

by diesel electric plants is 22277 t. The total emission

for cruise ships equipped by gas electric plant was

approximately 2521 t. The highest emissions for both

ship's categories were generated when the ships were

at berth because the manoeuvring and slow steaming

periods are shorter than the berthing period. As

regards the cruise ships equipped by the common

machinery plant, their emissions in the manoeuvring

and berthing were higher than during the slow

steaming. The total emission for this category of cruise

ships equipped by was approximately 305 t.

6 GUIDELINES FOR FURTHER DEVELOPMENT

OF THE CRUISING INDUSTRY WITH REGARD

TO CO

2 EMISSIONS

The cruising industry is making significant efforts to

reduce environmental impacts. The main priorities in

the coming years relate to the development and

identification of new technologies to use cleaner fuels

and make cruise ships more energy efficient. The

priority goal is to reduce the CO

2 emission rate by

40% by 2030 compared to 2008. Investments in the

energy efficiency of ships amount to more than $ 22

billion. In the coming years it is expected: [19]

− 44% of new build capacity will rely on LNG fuel

for primary propulsion,

− 68% of global capacity currently utilizes Exhaust

Gas Cleaning System, while 75% of non-LNG new-

builds will have Exhaust Gas Cleaning System,

− 100% of new builds will have Advanced

Wastewater Treatment Systems,

− 88% of new build capacity will have or be

configured to add Shore-side Power.

Additional Areas of Exploration are Battery

Propulsion, Advanced Recycling, Reduced Plastics,

Efficient Lighting, Solar Energy and Fuel Cell

Technology. Developing non-carbon emitting energy

is in line with the objectives set by the European

Union. The objectives until 2030 are as follows: [20]

− minimizing greenhouse gas emissions by 40%,

− increasing energy efficiency by 27 – 30%,

− increasing the share of energy from renewable

sources in total consumption by minimally 27%.

Finally, the IMO seeks to reduce greenhouse gas

emissions from international shipping by reducing

annual greenhouse gas emissions by at least 50% by

2050 as compared to a 2008 baseline, while at the same

time pursuing efforts to phase them out completely

[21].

7 CONCLUSION

The trend of increasing the number of cruise

passengers and berths is increasingly present in

Croatia, with the Gruž-Dubrovnik port holding the

lead position. Although cruising tourism is a driver of

the development of many economic activities, this

type of tourism contributes to air pollution by CO

emissions.

223

Ship emissions are a significant source of air

pollution and it causes a cumulative effect that

contributes to the overall air quality problems

encountered by populations, especially in nearby

areas, affects to the natural environment. In this

article, the exhaust emissions were calculated with the

activity-based emission model for the port of

Dubrovnik (Gruž), which is the significant cruise port

on Mediterranean. All major cruise lines include

Dubrovnik on their Mediterranean itineraries.

Dubrovnik handles around 600 cruise ship calls

annually.

The emissions generated from ships calling into

the Dubrovnik port may have a great impact on the

immediate environment and also on the health of

people living in its vicinity. This work estimates a

quarterly total of emissions released by cruise ships

calls Dubrovnik between 1st of March and 1st of June.

Although most of these emissions take place at sea,

the most directly noticeable part of shipping

emissions takes place in port areas and port-towns.

The total number of ship calls in the Dubrovnik port

for mentioned period was 155 (142 cruise ships

equipped by diesel electric plant, 4 cruise ships

equipped by gas electric plant and 9 cruise ships with

most common machinery plant). The engine powers

were approximately determined on gross tonnage

basis. The emission factors of CO

2 have been obtained

from the ENTEC ship emissions inventory study.

Ship's emissions were calculated by the ship activity-

based method which involves the application of

emission factors for each ship-activity (slow steaming

on arrival and departure, manoeuvring on arrival and

departure, and for berthed ship). The total quarterly

emission of CO

2 was 24530 t (cruise ships equipped by

diesel electric plant 22277 t, cruise ships equipped by

gas electric plant and 2521 t, cruise ships with most

common machinery plant 305 t).

The cruising industry is making positive strides to

make cruisers more energy efficient. However, the

results of CO

2 emissions reduction will only be visible

in the future.

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