Due to the utmost importance of international maritime transport within the global economy, shipping contributes substantially to the emission of pollutants and Greenhouse Gases. Consequently, it is called to reduce its environmental impact, in accordance with the regulations that will enter into force in the next years. In this framework, innovative technologies can find fruitful applications in new constructions, but there is still a significant number of operating ships that needs to be technologically updated. Nonetheless, since these ships may be already in the middle of their service life, revamping operations must take into account the purpose of both reducing pollution and avoiding long and expensive interventions. The sustainability-oriented production is one of the most discussed topics and in this paper, the authors aim at describing the potential technologies and solutions to adapt operating ships to the future emission threshold limits. Then, they propose a tool for supporting energy conversion studies on ships. The tool was tested on an Oil Tanker selected as a case study; different layouts exploiting the use of liquefied natural gas, ammonia, and methanol as alternative fuels were analysed. The considered technological solutions were compared on the basis of both technical and economic aspects. Indeed, technological feasibility and economic viability represent the most important discriminants for the diffusion of such innovations on a wide scale and in particular for commercial vessels employed predominantly in long and international voyages.
