## 1 Introduction  
The shipping sector is responsible for 2.5% of worldwide Greenhouse Gas emissions (GHG) annually [1], and therefore increasing attention and effort is being devoted to the decarbonisation of the shipping sector, through several energy audit initiatives [2], as well as international policies devoted to the improvement of the energy efficiency of ships [3] and research for technical solutions to increase the sustainability of the sector [4]. Within this wide and complex sector, the fishing field, with a total fleet of around 4.4 million vessels globally, has a strong impact on the overall effect of the shipping sector on climate change. Different alternatives have been suggested for the improvement of the energy valorisation on ships, starting from the analysis of the several sources of inefficiencies [5] and load distribution [6]. Among the solutions proposed, different power cycles, including Organic Rankine Cycles (ORC), Rankine, Kalina, and their combinations, for the production of steam and electricity were evaluated [7], even though the complexity of the system was found to represent a serious drawback for practical installation, especially considering the limited benefits, especially for long-distance shipping. On the contrary, the use of waste heat from the engine, which represents up to 50% of the overall energy output of the engine [8] for heating and cooling purposes, is a valid solution for the valorisationof an amount of energy that is generally considered as a contribution to the exergy destroyed. Indeed, the impact of refrigeration on the fuel consumption and, consequently, CO\({}_{2}\) emissions is relevant: the small pelagic fish, which are the most efficient in terms of fuel intensity, require up to 1000 L of fuel per ton of fish refrigerated and transported, whereas crustacean require up to 6000 L of fuel per ton [9]. Hence, it is clear that there is a significant space for energy efficiency improvement in the sector. During the last decade, several refrigerators and chillers that can be powered by waste heat were studied. A detailed review is presented in [10]. The systems proposed up to now are mainly ice makers, based on a discontinuous cycle for the production of ice flakes [11], chillers for air conditioning application on-board [12], and refrigerators for continuous cooling production at different temperature levels [13; 14; 15]. The application in an aggressive environment, such as the marine one, was specifically addressed in the design of various systems, considering corrosion issues and the effect of the movement of the ship [16; 17]. From such a literature review, it is clear that the vast majority of studies available are concentrated on the thermodynamic and dynamic efficiency of the system [17], or the development of prototypes for application on-board [18; 19; 20] and their testing [15; 21]. Only a few studies have actually considered how the whole energy system could be included on-board and the possible implications of the installation of such a system. For instance, in [14; 22], a complete system for providing heating, cooling, and refrigeration demand on a container ship was modelled in the dynamic systems modelling software TRNSYS, thus considering, on the one hand, the dynamic behaviour under realistic conditions, and on the other hand, the actual connections of all the components of the system. In [20], the effect of the sorption system was evaluated, in terms of weight and therefore extra fuel consumption, proving that the benefits arising from the use of such a system are strictly dependent on the routes followed and the duration of the cruise. Nonetheless, the integration of these innovative energy systems within the ship architecture and its already complex power generation system has not been properly addressed up to now. In [20; 23; 24], only the waste heat recovery system was included in the energy and environmental analysis of refrigeration systems for fishing vessels.