Holistic Energy Efficiency and Environmental Friendliness Model for Short-Sea Vessels with Alternative Power Systems Considering Realistic Fuel Pathways and Workloads


Energy requirements push the shipping industry towards more energy-efficient ships, while environmental regulations influence the development of environmentally friendly ships by replacing fossil fuels with alternatives. Current mathematical models for ship energy efficiency, which set the analysis boundaries at the level of the ship power system, are not able to consider alternative fuels as a powering option. In this paper, the energy efficiency and emissions index are formulated for ships with alternative power systems, considering three different impacts on the environment (global warming, acidification, and eutrophication) and realistic fuel pathways and workloads. Besides diesel, applications of alternative powering options such as electricity, methanol, liquefied natural gas, hydrogen, and ammonia are considered. By extending the analysis boundaries from the ship power system to the complete fuel cycle, it is possible to compare different ships within the considered fleet, or a whole shipping sector, from the viewpoint of energy efficiency and environmental friendliness. The applicability of the model is illustrated on the Croatian ro-ro passenger fleet. A technical measure of implementation of alternative fuels in combination with an operational measure of speed reduction results in an even greater emissions reduction and an increase in energy efficiency. Analysis of the impact of voluntary speed reduction for ships with different power systems resulted in the identification of the optimal combination of alternative fuel and speed reduction by a specific percentage from the ship design speed.

Funding source: This research was funded by the Croatian Science Foundation under the project Green Modular Passenger Vessel for Medi-terranean (GRiMM), (Project No. UIP-2017-05-1253) as well as within the Croatian–Chinese bilateral project “Energy Efficient and Environmentally Friendly Power System Options for Inland Green Ships” between the University of Zagreb, Faculty of Mechanical Engineering and Naval Architecture (Croatia) and Wuhan University of Technology (China). Maja Percic is supported through the “Young re-searchers’ career development project—training of doctoral students” of the Croatian Science Foundation, funded by the European Union from the European Social Fund (ESF). Ivana Jovanovic is supported through the “Young re-searchers’ career development project—training of doctoral students” of the Croatian Science Foundation.
Related subjects: Applications & Pathways

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