*2.1. Reference Ship Description*

A general cargo ship with main engine power of 3800 kW is chosen as the reference ship for integrating the steam reforming, HT-PEMFC and CO2 capture/liquefaction systems. Although the operational engine load depends on the ship design, in general, it can be much smaller than the engine total capacity [48]. Therefore, in this study, the systems are designed based on the average shaft power. This approach allows a more precise evaluation of the amount of CO2 emissions and energy consumption for CO2 capture/liquefaction on board. To calculate the average shaft power, a load factor that indicates the fraction of power needed by the engine to navigate at the average speed was calculated by using the average and maximum speeds. The product of load factor and total installed engine power (MCR) provides the average shaft power. The formulas for load factor and average shaft power are presented in the equations below. The detailed specifications of the reference ship, including the calculated load factor and average shaft power, are presented in Table 2 [49].

$$\text{Load factor} = \left(\frac{\text{Average Speed}}{\text{Max Speed}}\right)^3 \tag{1}$$

$$\text{Average shaft power } \left[ \text{kW} \right] = \text{Load factor} \cdot \text{MCR } \left[ \text{kW} \right] \tag{2}$$

In the present study, for simplicity of system design, we only considered the power required for propulsion excluding other hotel powers.


**Table 2.** Specification of the reference ship.
