The fishing sector is faced with emission problems arising from the extensive use of diesel engines as prime movers. Energy efficiency, environmental performance, and minimization of operative costs through the reduction of fuel consumption are key research topics across the whole maritime sector. Ship emissions can be determined at different levels of complexity and accuracy, i.e., by analyzing ship technical data and assuming its operative profile, or by direct measurements of key parameters. This paper deals with the analysis of the environmental footprint of a fishing trawler operating in the Adriatic Sea, including three phases of the Life-Cycle Assessment (manufacturing, Well-to-Pump (WTP), and Pump-to-Wake (PTW)). Based on the data on fuel consumption, the viability of replacing the conventional diesel-powered system with alternative options is analyzed. The results showed that fuels such as LNG and B20 represent the easiest solution that would result in a reduction of harmful gases and have a positive impact on overall costs. Although electrification and hydrogen represent one of the cleanest forms of energy, due to their high price and complex application in an obsolete fleet, they do not present an optimal solution for the time being. The paper showed that the use of alternative fuels would have a positive effect on the reduction of harmful emissions, but further work is needed to find an environmentally acceptable and economically profitable pathway for redesigning the ship power system of fishing trawlers.

Energy management strategies (EMS), which can coordinate the various devices to achieve efficient, low-carbon operation, are the focus of current research. In this paper, a parallel hybrid ship is used as the research target. First, the system structure of the target ship is analyzed and a power system model is built based on AMESim as a simulation validation platform. Second, a two-layer fuzzy logic control strategy, a dynamic programming (DP) algorithm and an improved fuzzy logic control strategy were designed based on Simulink, respectively. Then, co-simulation validation is carried out from the perspectives of energy consumption, emission, robustness, power quality and real-time performance. To further validate the real-time performance of the strategies, hardware-in-the-loop simulation (HiLs) is carried out based on dSPACE. The results show that the improved fuzzy logic control strategy is able to improve energy saving and emission reduction while ensuring stable, real-time performance, which is able to save 3.35% of fuel consumption and reduce 14.2% of CO2 emissions compared with conventional rules. This strategy can be a feasible solution to be applied to real ships at this stage.

Higher energy efficiency and lower environmental impact have become very important aspects in the evaluation of the design and operation of technical systems. The same goes for the fish farming sector, which continuously aims to reduce its environmental footprint as well as its operating costs. This paper reviews the energy needs of the fish farming sector and their impact on the environment, and discusses the possibilities of improving the environmental friendliness of this sector by employing a higher share of renewable energy sources. The fish farming process is divided into its constitutive phases: fish breeding with associated activities, transportation, and handling of grown fish, together with relevant processes; and final processing and distribution to the customers. For these phases, the energy consumption and associated emissions, depending on the energy source, have been assessed. The parts of the process with the highest potential for the integration of alternative powering options and consequent environmental improvements are identified. The case study deals with the fish farming process in Croatia, for which a set of alternative powering options has been proposed, considering the existing energy supply, i.e., import of fossil fuels and current Croatian electricity mix, as well as renewable energy potential, which is reviewed in the paper.