# Forecast Analysis of Pollutant Emissions of Cruise Ship Routes in Western Mediterranean
## 3 Materials and Methods
The most common configuration of power plants is composed of four engines; see Table 3. Additionally, part of the fleet analysed has up to six engines for propulsion purposes. Moreover, generally, all the engines of the propulsion power plant are of the same manufacturer. In this regard, Wartsila stands out among the manufacturers of marine engines installed in the sample of cruise vessels analysed; see Table 4. Few propulsion power plant configurations were identified with a combination of two different marine engine manufacturers, such as the combination of Caterpillar and MaK or Wartsila and Caterpillar engines. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Number of Engines Installed** & **1** & **2** & **3** & **4** & **5** & **6** \\ \hline Number of ships & 4 & 26 & 1 & 89 & 15 & 19 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Distribution of the cruise fleet analysed by number of engines installed for propulsion. Figure 2: Distribution of type of propulsion machinery among the cruise fleet analysed. Furthermore, a variety of configurations regarding the number of cylinders and their arrangement in the engines installed on cruise ships can be found. Four types of configurations were identified: all the engines of the propulsion power plant have the same number of cylinders, and all of them have a V-type (V) cylinder arrangement; all the engines of the propulsion power plant have the same number of cylinders, and all of them have an in-line type (L) cylinder arrangement; all the engines of the propulsion power plant have a V-type cylinder arrangement, combining engines of different numbers of cylinders; and the propulsion power plant is composed of both engines of V-type and in-line type cylinder arrangement. The V12 engine is the most common engine installed on the cruise fleet analysed, followed by the V16 and L8 engines; see Table 5. In the case of propulsion power plants with the V-type and in-line type cylinder arrangements, the most common scheme is the V12 and L8 arrangements, with 15 ships having this configuration. Once the type of propulsion machinery and output power for navigation of the fleet was available, the third step was to estimate the gas emission inventory. The inventory was performed for sailing at the service speed corresponding to 85% of the maximum continuous rating (MCR) of the engine. The activity of the cruise ships is modelled through Equation (1) to estimate the emission quantity of SO\({}_{2}\), NO\({}_{x}\), and CO\({}_{2}\). Equation (1) is applied to each vessel on each route, also considering the number of connections. Similar approaches can be found in the works of [PERSON] et al. [PERSON] et al. (2013) and [PERSON] et al. [PERSON] et al. (2014). \[E_{i}=P\cdot L_{f}\cdot T_{a}\cdot E_{f}\left(i\right)\cdot\mathit{SFC}, \tag{1}\]  
where \(E_{i}\) is the propulsion machinery emission during sailing (kg), \(P\) is the propulsion machinery output power (kW), \(L_{f}\) is the load factor for main engines (in this case 0.85), \(T_{a}\) is the activity duration (h), \(E_{f}\left(i\right)\) is the emission factor (kg/kg\({}_{\mathrm{fuel}}\)) of pollutant \(i\), which are SO\({}_{2}\), NO\({}_{x}\), and CO\({}_{2}\), respectively, and \(\mathit{SFC}\) is the specific fuel consumption (kg/kW\(\cdot\)h). \begin{table}
\begin{tabular}{l c} \hline \hline
**Engine Manufacturer** & **Number of Ships** \\ \hline Wartsila & 70 \\ MAN-B\&W & 19 \\ MaK & 15 \\ Sulzer & 13 \\ MAN & 11 \\ Caterpillar & 5 \\ Caterpillar-MaK & 4 \\ Wartsila-Sulzer & 2 \\ Wartsila-Vasa & 2 \\ B\&W Akers & 1 \\ Cummins & 1 \\ Deutz & 1 \\ MAN-Bremer Vulkan & 1 \\ MAN-Mitsubishi & 1 \\ MWM & 1 \\ Normo-Bergen KVMB & 1 \\ Pielstick-Alsthom & 1 \\ Pielstick-Crossley & 1 \\ Rolls Royce & 1 \\ Sulzer-Cegelski & 1 \\ Wartsila-Pielstick & 1 \\ Wartsilla-Caterpillar & 1 \\ \hline \hline \end{tabular} Source: Authors’ elaboration.  
\end{table} 
Table 4: Distribution of the cruise fleet analysed by engine manufacturer. Following the research of [PERSON] et al.