The newest cruise ships can guest a constantly increasing number of passengers and concentrate their environmental impact on the limited areas interested by their path. The generated solid waste contributes significantly to this impact; therefore, we propose an innovative solution for recovering embedded energy from that garbage. In more detail, we study the feasibility of an absorption plant able to exploit the residual energy of the flue gas of the ship’s incinerator. No payload space shall be sacrificed to install the considered absorption plant. Furthermore, it can be integrated with the existing plants providing for a limited number of heat exchangers. The recovered energy can be used to control the temperature of the refrigerated storerooms; operating simultaneously with, or in place of the existing compression vapors system already installed; it allows a reduction of the CO2 emissions and of fuel consumption. We show that the proposed approach can be applied to a variety of cruise ships, independently of their tonnage or passenger capacity.

Here we report over possible optimizations onboard cruise ships in the management of glass, paper and cellulosic waste, ranging from simple rationalization of the materials' use (for glass and paper) to the recovery of some of the energy embedded in paper and other cellulosic waste. This latter option is investigated considering two possibilities: i) the recovery of thermal energy from incinerator's flue gas by means of an absorption plant, ii) the production of syngas to be directly fed to the ship engines. For each option, we calculated the achievable benefits in terms of reduced fuel consumption, avoided CO2 emissions and cost savings (evaluated on the basis of the avoided fuel consumption). Finally, on the basis of the previously calculated benefits, we defined three different scenarios, each including the rationalization of glass and paper waste management, topped by different combinations of thermal energy recovery/syngas production. We then evaluated these scenarios in terms of environmental and economic benefits. This analysis showed that even trivial approaches, as a simple rationalization of paper consumption, can allow consistent advantages over existing waste management policies; moreover, syngas generators for treating cellulosic waste emerged as very effective tools for lowering the environmental impact of modern cruise ships. Joining these two strategies allows notable savings in terms of fuel, CO2 emissions and ship operational costs, and could represent a path for sizably reducing the environmental footprint of cruise ships.

Hot potable water preparation in ships requires lots of energy from the power plant; this is particularly true in modem cruise ships with a high demand of potable water for people, restaurants, spa and pools. Usually the required amount of hot water is instantly produced using a number of different energy sources available on board. However, the use of direct heaters on peak demand conditions increases fuel consumption and greenhouse gas emissions. This is especially important in the case of ship in port configuration, due to the reduced number of active engines and therefore the reduced amount of waste heat from the cooling line usually employed for this task. This paper investigates possible solutions to size a hot water thermal storage in order to compensate the mismatch between heat generation during cruise and heat required during ship in port configuration. The performances of different solutions are compared using dynamic thermal simulations of the ship's hot water distribution system with different regimes and time dependent heat requirements. Moreover it will be introduced the use of PCM materials with the aim to further improve system's performance. (C) 2018 The Authors. Published by Elsevier Ltd.