The worldwide effort on the environmental issue in the maritime field has led to always more stringent regulations on greenhouse gas emission (GHG). In this perspective, the International Maritime Organization has developed regulations intended to increase the ship's efficiency and reduce GHG emissions both in design phase, through the introduction of an Energy Efficiency Design Index (EEDI), either in management phase, adopting the Ship Energy Efficiency Management Plan (SEEMP). In this challenging perspective, several approaches and technologies adopted in land-based engineering can also be advantageous for marine applications. This is the case of the Distributed Energy Resources (DER) solution applied in land-based microgrids, which increases both the system's efficiency and reliability. This work is primarily focused on methodological aspects related to the adoption of a DER solution on-board cruise ships, with the integration of different energy sources in order to pursue a more flexible, reliable and sustainable management of the ship. In this context, another engineering best practice developed for land-based applications that is further investigated in the paper is related to the on board thermal energy recovery issue, revisited due to the implementation of the DER solution.