A multi-criteria approach for comparing alternative fuels and energy systems onboard ships

This paper aims to present the upgrade of the Helper for Energy Layouts in Maritime applications (HELM) software tool, developed by the authors to compare traditional and innovative systems for energy production and storage onboard maritime vessels. The algorithm adopts a multi-criteria method and it carries out the analysis on a large and updated database of market solutions. A wide range of maps is implemented in the tool, correlating costs, volumes, weights, emissions and fuel environmental hazards with energy demand, applicative scenario and vessel type. The equations implemented in the software and the algorithm employed to evaluate and compare the technologies are reported. In this work, four different vessels are investigated, namely: (i) a small sail yacht; (ii) a small passenger ferry for inland water navigation; (iii) a large cruise ship; (iv) a large container ship. For each case study, the choice of the best solution is performed, considering the constraints, the inputs and the single parameters: in all cases, the solution chosen corresponds to the real one installed on board or to a solution that is going to be installed. It is worth noting that the multi-criteria analysis has a general approach, allowing to give preliminary information on the best energy system solution, also to comply with the application requirements (i.e. pollutant emissions in ports and restricted areas).