ABSTRACT

Reducing carbon dioxide (CO2) emissions is crucial in terms of environment and world climates, and the International Maritime Organization (IMO) has accelerated its works to limit greenhouse gas emissions released from international maritime activities in recent years. Various methods and technologies have been proposed to reduce CO2 emissions from ships until nowadays. Fuel cells are one of these technologies and they can reduce CO2 emissions to zero, depending on the fuel used. In this study, electrochemical and thermodynamic modeling of the solid oxide fuel cell (SOFC) as an auxiliary power source for a coaster and simulation in Aspen HYSYS software is carried out. In order to make a more effective comparison in terms of feasibility and cost with alternative CO2 emission reduction methods, an economic analysis of the system is made over unit CO2 reduction cost. The economic analysis is carried out based on the cost increase and reduced CO2 emission values resulting from the replacement of the reference auxiliary power system of the ship used with the SOFC power system proposed in this study. The effects of different operating temperatures and current densities of the fuel cell on the cost of the system are investigated using the model established. In addition, the effect of fuel cell degradation on cell potential reduction is taken into account in this study for the first time in studies conducted for ships. As a result of the parametric study, the selection of the current density in the conditions examined reduces the unit CO2 reduction cost up to 10.0% and the selection of the temperature reduces the unit CO2 reduction cost up to 26.1%. It has been calculated that the system has high thermal efficiency of 51.1% and a reduction cost of 302.2 USD/ton CO2 under operating conditions that minimize costs. It has been calculated that 65% of the total cost of the SOFC power system under the specified condition is hydrogen as the fuel used. The efficiency with the degradation effect is calculated as 43.6% on average at the end of the fuel cell life, and this efficiency is 20.7% greater than the reference auxiliary power system. Compared to the ship in the reference conditions, CO2 emissions decreased by 24.3% with the auxiliary power system proposed in the study.