The maritime shipping industry is under increasing pressure to reduce its environmental footprint in response to ambitious short- and long-term decarbonization targets set by the International Maritime Organization (IMO). These targets focus primarily on reducing greenhouse gas emissions and accelerating the transition toward more sustainable ship propulsion systems. As a result, shipowners, designers, and policymakers are actively exploring alternative energy carriers that can replace or complement conventional fossil fuels. However, evaluating the feasibility of these alternatives during the early stages of ship design remains complex and time-consuming. Current ship design generators and feasibility assessment tools often lack the capability to systematically compare different energy carriers in a consistent and automated way. This research aims to address this gap by developing a method and corresponding tool that automates early-stage feasibility studies for ships powered by alternative energy carriers.

The primary objective of this research is to enable the automated exploration of design alternatives based on different energy carriers while supporting early-stage decision-making in ship design. The study focuses on four promising alternatives to conventional marine fuels: batteries, hydrogen, ammonia, and methanol. These energy carriers are evaluated through several key parameters that influence ship design, including energy density, storage conditions, tank types, applicable regulations, power generation technologies, and spatial requirements for engine and tank rooms. These aspects are essential for determining the feasibility of integrating alternative energy systems into vessel designs and for generating realistic general arrangements during the conceptual design phase.

The research begins with a comprehensive literature review on alternative energy carriers and their implications for ship design. This review also examines the capabilities of existing ship design generators. The analysis reveals that current design generators do not explicitly support the independent creation of design spaces for different energy carriers prior to comparing their optimal configurations. Consequently, designers lack an automated framework that allows them to explore and evaluate multiple energy carrier options simultaneously within a consistent modeling environment.

To address this limitation, the study proposes a novel design method and develops a parametric tool capable of automatically generating and evaluating alternative ship designs based on different energy carriers. The tool creates separate design spaces for each energy carrier and evaluates them according to predefined performance criteria such as speed, autonomy, lightweight ship weight (LSW), and total resistance. The generated design alternatives can then be compared to identify the most suitable energy carrier configuration for a given set of operational requirements.

The tool was tested through five case studies involving different types of cargo vessels. The results demonstrate that the developed method can generate feasible design solutions and provide useful insights into the comparative performance of the considered energy carriers. Among the tested options, methanol generally produced the most favorable results in terms of achieving the required speed and autonomy while maintaining relatively low lightweight ship weight and total resistance. Ammonia ranked second, followed by hydrogen and battery-based systems. However, the study also identified several discrepancies between the generated models and real-world vessel designs. In particular, the lightweight ship weight was consistently underestimated, leading to overly optimistic performance predictions for certain configurations.

Validation of the tool was conducted by comparing calculated lightweight ship weight and resistance values with known reference data. The average deviation was approximately 20% for lightweight ship weight and 11.3% for total resistance. Although these deviations highlight the need for further refinement, the results indicate that the proposed method can provide meaningful insights during the early stages of ship design.

Overall, this research demonstrates the potential of automated design tools to support the evaluation of alternative marine fuels in early-stage ship design. Future improvements should focus on refining weight estimation methods, incorporating additional ship systems, and integrating three-dimensional modeling capabilities to further enhance the tool’s accuracy and decision-support capabilities. ... Read more

This thesis delves into the intricate process of formulating an answer to the pivotal research question:

"What are the design characteristics of an economic high speed nuclear container vessel?"

The report systematically unfolds in six chapters, primarily focusing on a comprehensive literature study.

The exploration begins with an in-depth analysis of various nuclear reactors, emphasizing aspects such as load following, capital costs, fuel expenses, operational and maintenance costs, and decommissioning expenditures. Key challenges in implementing these reactors within ship designs are scrutinized, including considerations of safety, location, and refueling intervals.

Subsequently, the study investigates the intricate relationship between vessel speed and economic factors such as income, operational costs, and freight rates in liner shipping. Operational costs, especially fuel expenses, are found to significantly impact speed-dependent factors.

Concurrently, the impact of speed on hull shape and propulsors is evaluated, revealing a proportional increase in wave-making resistance at higher speeds and necessitating a reevaluation of power estimation methodologies.

The literature study is concluded with an assessment of three types of propulsors, where conventional propellers emerge as the preferred choice due to their efficiency, power range, and scalability.

The research then starts with the economic speed determination process, vital in shaping the vessel's design. This involves constructing a resistance curve based on a volume-scaled high-speed model vessel and factoring in components like CAPEX, OPEX, voyage costs, and freight rates. The study highlights the significant influence of freight rates on speed for all cases and underscores the viability of nuclear-powered vessels in achieving higher economic speeds due to lower fuel costs, especially over extended service lives.

With these foundational insights, the design process is initiated, emphasizing the optimal balance between speed, capacity, and real-world constraints. A scaled-down version of the nuclear concept vessel is developed, demonstrating a decrease in resistance while adhering to stability criteria. The resulting nuclear vessel design showcases a streamlined hull shape, minimal general arrangement alterations, and enhanced stability, with a notable preference for a three-propeller layout to optimize performance.

In conclusion, this study presents a concept design for a 20,000 TEU nuclear container vessel that achieves an increased economic speed, leading to design refinements in hull shape and propulsors. The research underscores the viability of nuclear propulsion in enhancing the efficiency of container shipping, providing valuable insights for future innovations in maritime transportation. ... Read more

Nuclear power is currently not a commonly used option in commercial marine applications, despite its potential for significant emission reductions. This thesis is an overview of what has been done before, and what the potential is of modern marine nuclear power applications considering the long-term goals of harmful emission reduction in the maritime industry.
The concept of nuclear power is discussed, followed by the current state of nuclear power in both the shore-based, naval and the mostly historic marine application. The regulations for the marine application are noted to be outdated and require significant work for a successful application. Finally, the societal aspect of nuclear power is highlighted, as societal acceptance is not self-evident for nuclear power applications.
Different developments in the field of nuclear power are addressed, with specific interest in the SMR (Small Modular Reactor), concepts that are part of the “generation IV” family, and concepts that can operate using thorium as fuel. Multiple options are considered, from the well-established PWR (Pressurized Water Reactor) to the gen IV concepts: the HTR/VHTR (high/very high temperature reactor), fast reactors in both gas-cooled, liquid-metal and sodium cooled varieties (GFR, LFR, SFR) and finally the MSR (Molten Salt Reactor). Of these the HTR/VHTR and MSR in small modular reactor form are considered the most attractive option for the marine application, due to their passive safety, high burnup, high operating temperatures, and possibilities for thorium use in the future.
Criteria are established that are of importance to a marine propulsion and power generation system, establishing a framework for an implementation. Focusing on topics as: efficiency, transient loading capabilities, environmental impact, economic viability, size, and weight.
For power conversion (linking the heat generation to power/electricity for the vessel) the open-cycle Brayton turbine with a heat exchanger is selected as most suitable, despite the steam turbine being more developed and projecting a possible higher efficiency. The choice for the open-cycle Brayton turbine stems from the system size and weight reduction, along with a relatively easily implementable heat rejection system for enhanced load following capabilities. The selected heat exchanger is of the helical coil type, as this is significantly more developed and proven than the PCHE.
The most suitable layout is determined to be an all-electric layout, as this will greatly improve reliability (enhancing safety by redundant arrangements) and make the implementation easier applicable to a host of vessels. The electric layout allows for the combination of additional system such as batteries and emergency power. This layout is then combined with the open Brayton turbine and its heat rejection capabilities to ensure a system that is both compact as well as highly capable in performance.
Finally, four suitable concept vessels were established that allowed for a like-for-like replacement with a nuclear propulsion and power generation system. This allowed for a comparison to the conventional fuel-based systems where it is shown that the implementation of nuclear power can provide very large CO2eq reductions (over 98%), while reducing size and weight if vessels of suitable size are selected. The trade-off to this reduction is the production of nuclear waste, alongside the increased upfront cost due to the high capital investment associated with nuclear power.
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