In this study, the life cycle assessment (LCA) was used to compare the environmental performances of a conventional bulk carrier (baseline vessel) and a wind-energy-optimised bulk carrier equipped with modern on-board technologies working in synergy (future vessel). Fossil fuels was used for the baseline vessels, whereas the future vessel used liquefied biogas (LBG) and hydrotreated vegetable oil (HVO) as marine fuels. The entire life cycle phases of the vessels, namely, construction, operation, maintenance, and end-of-life, were included. The results showed that the future vessel could reduce 31.23% energy consumption, compared to the baseline model. Furthermore, the significant reduction in CO₂ (48.6%), NO_X (88.6%), SO_X (100.0%), and black carbon (94.0%) in the tank-to-wake phase was achieved owing to energy-saving technologies working in synergy and alternative fuels. This study emphasizes the vital role of energy efficiency, technologies, and alternative fuels to achieve the zero-emission ambition of the maritime industry. Furthermore, the impacts of ship construction, maintenance, and end-of-life need to be fully considered in order to decarbonize vessel from a life cycle perspective.

The selection of a proper machinery system is one of the primary decisions to be taken during the ship design phase. Nonetheless, this selection is made challenging by the presence of a variety of alternatives, and by the limited data availability at the early stages of the design phase. An optimization framework is presented in this paper, supporting decision making at the earliest stages of the ship design process. The framework is suitable to perform the screening and the selection of optimal machinery configurations for a predefined ship operational profile, and it includes both linear and non-linear optimization routines. The results of the linear and the non-linear approaches are compared, and indications on what conditions are the most suitable for the application of one or the other approach are provided. Both approaches are tested for two case studies, a bulk carrier and a small cruise ship. The results indicate that both optimization approaches lead to the same layout of the machinery system, but to slightly different unit scheduling. This suggests that the use of the linear approach is suitable for design purposes, but less appropriate for operational optimization. In addition, the findings of the work suggest that the trade-off between fuel consumption and volume of the engines should be considered when selecting the machinery system for a ship.

Interest in more sustainable energy sources has increased rapidly in the maritime industry, and ambitious goals have been set for decreasing ship emissions. All industry stakeholders have reacted to this with different approaches including the optimisation of ship power plants, the development of new energy-improving sub-systems for existing solutions, or the design of entirely novel power plant concepts employing alternative fuels. This paper assesses the feasibility of different ship energy sources for an icebreaking Arctic research ship. To that end, possible energy sources are assessed based on fuel, infrastructure availability and operational endurance criteria in the operational area of interest. Promising alternatives are analysed further using the evidence-based Strengths, Weaknesses, Opportunities, and Threats (SWOT) method. Then, a more thorough investigation with respect to the required fuel tank space, life cycle cost, and CO₂ emissions is implemented. The results demonstrate that marine diesel oil (MDO) is currently still the most convenient solution due to the space, operational range, and endurance limitations, although it is possible to use liquefied natural gas (LNG) and methanol if the ship’s arrangement is radically redesigned, which will also lead to reduced emissions and life cycle costs. The use of liquefied hydrogen as the only energy solution for the considered vessel was excluded from the potential options due to low volumetric energy density, and high life cycle and capital costs. Even if it is used with MDO for the investigated ship, the reduction in CO₂ emissions will not be as significant as for LNG and methanol, at a much higher capital and lifecycle cost. The advantage of the proposed approach is that unrealistic alternatives are eliminated in a systematic manner before proceeding to detailed techno-economic analysis, facilitating the decision-making and investigation of various options in a more holistic manner.