The urgent need for alternative ways of vessel propulsion over the past few years created a growing interest in rediscovering wind as a source of propulsive force. While many concepts for harnessing the power of the wind have been developed so far, their actual implementation on real ships still remains at a scarse level since it brings with it many challenges. These challenges include the design of the wind assisted propulsion systems to fit the confines and meet the demands of each individual vessel they operate on. The re-discovery of the Flettner Rotor - an idea first brought up by German engineer Anton Flettner - opened up a new realm of possibilities for using that concept on modern cargo and passenger vessels. This research project aimed to deepen the already existing base of knowledge by extending it and providing a methodology within the context of numerical simulations for developing and assessing rotor sails and their placement on the decks of cargo vessels. This includes a detailed analysis of the influence of some of the main design parameters of these rotors. A dual rotor setup was examined to highlight potential interactions between the individual rotors of a multi rotor setup. This dual rotor setup was compared to a target rotor. The latter was designed based on the findings from an analysis of rotor design parameters. Both the target rotor and the dual rotor setup are subjected to three different wind conditions, varying in their direction. The spin ratio was observed to be the primary operational parameter to influence the generation of lift and drag, with higher spin ratios resulting in higher lift and drag coefficients throughout all examined geometric configurations. The analysis also found that both the aspect ratio and disc diameter ratio have an influence on the lift and drag coefficients, with lift coefficients being proportional to rotor aspect ratio, while the drag coefficient was observed to be inversely proportional to aspect ratio. The disc diameter ratio was found to have a major influence on drag, with higher disc ratios yielding lower drag coefficients, especially at higher spin ratios. The dual rotor setup showed a noticeable interaction between the rotors in a beam wind condition due to a change in the angle of inflow on the downstream rotor. Pressure distributions on both sides of the rotor were also analyzed to further highlight the reasons behind the observed effects for both parts of the analysis, showing dominating effects on the suction side.
Shipping is highly efficient yet a significant greenhouse gas emitter. Achieving the IMO's 2050 carbon-neutrality target demands exceptionally efficient new vessel designs. However, ship design is complex due to the vast number of interacting options - e.g. hybrid electric architectures, renewable integration, sector coupling, and energy storage. Energy system design remains a largely manual, iterative process based on prior experience, often overlooking unconventional concepts. The Maritime Energy System Optimizer (MESO) addresses this gap. MESO is a modular Python platform optimizing the architecture, dimensioning, and operation of sector-coupled ship energy systems via a genetic algorithm. Fitness is evaluated through operational, component, and volume costs, with operation optimization using the open energy modeling framework. Its novelty lies in unbiased architecture optimization over dynamic load profiles, reducing design iterations. MESO is demonstrated in two case studies - a cruise ship's multi-energy system and a container ship's auxiliary electrical system - identifying efficient, unconventional configurations.
The inland waterway transport sector faces challenges such as digitalization, adaptation to climate change and the integration of alternative propulsion technologies. Given the long service life of ships, the targets agreed in the Mannheim Declaration for reducing air pollutant and greenhouse gas emissions and the taxonomy screening criteria require the rapid development of measures to increase environmental sustainability. Simply further improving the already inherently good efficiency of shipping is not enough. The introduction of the EU Emissions Trading System, the Corporate Sustainability Reporting Directive and approaches currently being developed to assess greenhouse gas intensity of inland waterway transport will further promote the avoidance of CO2 and other greenhouse gases. Today, fossil diesel fuel is still widely used in inland waterway transport. The bio-based fuel HVO has also been available for some time, but its availability is limited by the need for sustainable feedstock. A large number of pilot projects have been launched in recent years with the alternative energy sources hydrogen and methanol, as well as batteries. As no clear trend towards a particular technology is yet apparent, other options such as ammonia are being considered in the sector. Ammonia is also a suitable storage and transport medium for renewable green hydrogen. However, the combustion properties and safety requirements of ammonia pose major challenges for its use as a motor fuel. The CAMPFIRE consortium is running several projects on the conversion and storage of green ammonia as part of future energy systems. One of these projects is developing a propulsion system for inland waterway vessels that runs on pure ammonia as fuel. The main components of this system are an ammonia cracker, which converts a partial flow of the fuel into hydrogen, and a high-speed combustion engine that runs on liquid ammonia and a small amount of hydrogen as an ignition enhancer. The CAMPFIRE Open Innovation Lab (COIL) is currently being built in Poppendorf near Rostock to test the technologies developed. Various configurations (ignition, injection, combustion chamber design, etc.) were tested and evaluated as part of systematic combustion process investigations for the engine as the central energy converter for ship propulsion. The engine achieves comparable performance values and efficiencies to the conventionally operated basic diesel engine. An exhaust gas aftertreatment system will be used to comply with emission limits. It can be assumed that this system can consist of already known technologies. Based on the results obtained, a concept for a prototype engine was derived, which will be examined in detail at COIL in conjunction with the ammonia cracker. The use of ammonia as a fuel also leads to new requirements for ship design. Due to the hazardous substance classification of ammonia and the potential environmental hazard, appropriate safety precautions must be taken. Using the example of an existing ammonia tanker that operates on the Rhine and its tributaries, a concept was developed for the integration of the above-mentioned propulsion system, including the fuel tank and the fuel treatment system. The planning of the conversion of the inland vessel, taking into account the necessary safety measures, was evaluated as part of a risk analysis.
The size of Wind-Assisted Propulsion System (WAPS) installations, exploited to reduce fuel consumption and emissions, is growing. Ship stability is critical and typically ensured through additional stability criteria, although a harmonized regulatory approach is currently non-existent. This paper presents a limited-scope case study analysing selected criteria using the E-ship1, perhaps the first rotor sail equipped newbuild. Different rotor sizes visualize the effect of variations between the additional criteria and the impact of passive depowering. This study demonstrates that current criteria are unsatisfactory and that the effect of operational factors, not unilaterally considered, can be significant. The maximum wind velocity at which rotor sails may be operated varies significantly with criteria, and rotor sails' impact on stability is not as significant as traditionally assumed, attributable to their passive depowering behaviour. Criteria optimisation and the use of type-specific criteria may therefore carry considerable benefits, enabling a safe increase of operational efficiency.
