To reduce global warming and air pollution, the maritime industry is searching for solutions to reduce fuel consumption. This thesis focuses on the reduction of generator running hours and fuel consumption of Dynamically Positioned (DP) vessels. In this ship type, redundancy of the power generation system is regularly achieved by running on one generator more than strictly necessary in every engine room. Thereby, these vessels make superfluous running hours and unnecessary fuel consumption. Previous research in this field focused on installing a hybrid system in every separate engine room to replace this redundant running generator and achieve the power generation redundancy by a battery which is temporarily used in case of a generator failure. Since DP vessels normally operate on two separate engine rooms for safety, this results in two separate hybrid systems, i.e. a double-battery hybrid system. To reduce investment costs of a hybrid DP vessel, this thesis concentrates on finding a power management strategy that allows a single hybrid system to be installed on board, which is only connected to one of the engine room grids in case of a generator failure. A single-battery hybrid system cannot be connected to both engine room grids continuously -in contrary to the double-battery hybrid system- because this would cancel the independence of the separate engine rooms. Therefore, in the single-battery hybrid system, no back up power is present in case of an increase in power demand in one of the engine rooms. In present DP vessels, this back up power is supplied by the redundant generator. When using a double-battery hybrid system, this back up power is supplied by the continuously connected hybrid system. Therefore, for a single-battery hybrid system, the starting control decision algorithm of the power management system (PMS) should decide on starting an additional generator prior to a rise of the power demand.

Two methods for this starting decision algorithm were tested. Firstly, a mathematical-statistical method using a mathematical model for DP load forecasting and a statistical model for pipe laying load forecasting was tested. This model was found not to work properly. Secondly, a multiple linear regression model that predicts the height of power peaks based on environmental parameters like wind and waves was tested which was found to work appropriately. To assess the feasibility of using either a double-battery hybrid system in combination with a simple starting decision algorithm, or a single-battery hybrid system in combination with a smart starting decision algorithm, these two hybrid system options were compared to the current situation that uses a redundant generator in every engine room. These three system options were compared in terms of investment costs, fuel consumption, generator running hours, planned maintenance costs, and reliability. For this comparison, the DP pipelaying vessel Pioneering Spirit was used as a case vessel. To find the investment costs, a hybrid system was designed for this purpose. To find the fuel consumption, generator running hours, and planned maintenance costs, full year time domain simulations of the hybrid systems in operation were performed using measured power demand data from the case vessel during pipelaying. For this analysis, a mathematical model of the power generation system was used. The reliability assessment of the different systems was performed using fault tree analysis.

The single- and double-battery hybrid systems both show a significant fuel consumption reduction of 8.4 and 9.0% respectively. When also taking into account the investment costs, generator maintenance cost reduction, and battery depreciation, the payback time of these hybrid systems is 0.9 and 1.7 years respectively. The difference in payback time is mainly caused by the difference in investment costs between the single- and the double-battery hybrid system.

For a single-battery hybrid system for DP vessels, a multiple linear regression model based starting decision algorithm works appropriately. However, although the multiple linear regression model based starting decision algorithm was tested positively in simulations using the available power data, in case of an unforeseen power peak that was not related to one of the input parameters of the regression model, the power generation system lacks back up power. Therefore, the reliability of the single-battery hybrid system is insufficient when using it for DP applications. Especially when taking into account the minor absolute difference in payback time, for the replacement of the redundant generators in DP vessels, the robust and simple double-battery hybrid system is preferred over the small and smart single-battery hybrid system. ... Read more

Environmental regulations are continuously raising the bar towards more advanced diesel engine designs ca- pable of minimizing the emissions of polluting substances. The recent IMO Tier III legislation, entered into force in 2016, is forcing the engine manufacturers to meet a NOx reduction of more than 70% from Tier II for all the ships sailing in designated NOx Emission Control Areas (NECA). Although these zones are, up to now, limited to the North American and U.S. Caribbean Sea NECAs, future regions, such as the North Sea and Baltic NECA in 2021 as well as stricter national and port regulations, are increasing the uncertainty regarding the possible compliance methods.
The Selective Catalytic Reduction (SCR) represents a flexible, proven and commercially available technology capable of reducing more than 80% of the NOx in the exhaust gas. Its adoption started in the ’70s and was aimed at the reduction of stationary source emissions. From early 2000, it has been extended to the automotive industry in order to meet the Euro and EPA legislation for heavy duty and light diesel engines. Despite the evident disadvantages of the high installation cost and the considerable space requirements, the application of the SCR is subjected to a number of operating limits such as the narrow optimal temperature window and the slip of byproducts originated from the chemical reactions. These limitations can be even more severe when the diesel engine undergoes transient and dynamic operations.
The main objective of this research is to gain insights into the behaviour of the SCR technology under steady-state and dynamic operations of the diesel engine. After an accurate literature review of the working principles, reaction kinetics and modeling approach, a first principle model of the SCR has been developed to fulfill the scope. A 1D single channel approach, discretized along the reactor length, has been adopted to sim- ulate the heat exchange and the chemical reactions occurring in the catalyst. To facilitate the integration of the designed model with an existing diesel engine model available in the Maritime and Transport Technology Department of the 3me faculty, the resistance and volume approach has been selected. After the verification of the SCR model, the integrated system "SCR+Engine" has been tested under steady-state conditions, to an- alyze the effect that the added back pressure has on the engine performance, and under dynamic conditions, to simulate "real" load case scenarios that the SCR might experience.
The designed model, although limited from the chemical reaction point of view, is able to predict NOx reduction and ammonia slip under steady-state and transient operations. It can be further used in an early design phase to investigate the feasibility of the SCR inclusion in the drive trains of ships. Future studies are recommended to optimize the model, by taking into account the sulphur influence on the reduction efficiency and the catalyst aging, and to validate it with real experiments on marine SCR systems. ... Read more

After years of using fossil fuel, the transition to renewable energy sources need to be made to limit the increase in temperature and to support the future energy demand. To support and speed up the transition phase from fossil fuels to renewables it is necessary to decrease the costs. Offshore Wind Turbines are widely used for the production of renewable energy and several Offshore Wind Turbine projects are planned for the future. Most of the Offshore Wind Turbines are founded by monopile, large steel tube, to support the wind turbine. Nowadays, these monopile be installed by either jack-up vessel or moored floating vessel. However, these installation method come with a major drawback: the installation procedure is time consuming. A new installation method is propose to reduce the installation time. This thesis focus of the feasibility to install the monopile with a dynamically positioned (DP) vessel. The
required station keeping situation is faster achieved with a DP vessel. Due to the footprint of the DP vessel relative to an earth fixed position, a vessel motion compensated pile gripper is used to maintain the upright position of the monopile and to decrease the interaction forces between vessel and monopile. Adding the monopile to the vessel is an off-design condition for the DP controller. During the early hammering phase of the monopile, the monopile have limited interaction with the soil and is unstable. The upright position is maintain by the gripper frame. The forces from the gripper frame on the monopile are reaction forces on the vessel. Beside these forces, environmental forces are acting on the monopile and via the gripper frame acting on the vessel. The forces on the vessel could lead to unstable behavior and/or increased vessel footprint. A simulation model is build to investigate the behavior of the DP vessel during the operation. A industry used DP simulator and a simulation model of the Bokalift1 is used. A model of a typical shallow water and deep water monopile is build. A hydraulic based gripper frame is simulated with an inclination controller and a induced vessel motion controller which need
to maintain the upright position of the monopile. The inclination controller is tuned with a higher bandwidth compare to the bandwidth of the DP controller to prevent motions of the monopile is the same frequency range as the linear motions of the vessel. The forces from the gripper frame are fed into the Kalman filter of the DP controller. This is done to prevent a drift of the vessel when the gripper frame starts acting on the vessel. In all simulation cases with governing environmental conditions, the vessel could maintain stable behavior. The rotations of the monopile are in the same frequency as the first order wave forces on the vessel. This relative high frequency motions to not significantly amplify the position of the DP vessel. However, despite the fact of feeding the Kalman filter, a larger drift is observed in case of the large, deep water monopile in the operation stage when the gripper frame force is introduced to the vessel. This increase the requirement on the envelope of the gripper frame. The requirement on the gripper frame is given in terms of power, force and envelope based on governing environmental conditions. The requirements on the gripper frame are assumed to be within an acceptable magnitude. The operation seams to be promising in the future. ... Read more

In this graduation thesis the feasibility of a camera as sensor for nautical operations is investigated. In
aerospace and automotive industries autonomous vehicles are already widely tested and used. However
the marine industry has fallen behind in this development. Therefore this research is focussing on
automation in the maritime sector. First a system was developed which measures distance and heading
from a video feed. Thereafter simulink models were made to develop a system that autonomously can
perform nautical operations. For this research multiple operations have been modeled. First of all
the platform approach and the replenishment approach. In these operations the system should be able
to approach a stationary or moving target. Also station keeping after the approach is required. The
complexity of the operations was increased with the choice for follow the leader from the maneuvering
operations. Finally the avoidance of upcoming collisions was modeled. The models for all of these
operations were rst developed and tested with an oine model. This enabled a quick and accurate
controller tuning. The rst real test for these models was done in a ship handling simulator. Here the
models were tested and the in
uence of environmental conditions was measured. In the simulator all
models performed quite well. However the performance is largely limited by the choice for the camera
and environmental conditions. The most interfering conditions are lateral incoming waves, fog and light.
Models for small scale testing were developed, but the communication between dierent components and
the control system proved to be a large issue. Therefore these models could not be tested. All in all
this research shows that after improving system component, a camera system can very well be used as a
sensor for autonomous operations at sea. ... Read more

The rapid rate in technological advancements leaves little to none options for our environment to react. The excessive use of "conventional" energy is bringing planet Earth to its knees. However, people started recognizing the value of renewable energy sources.
One of the major renewable sources is the wind energy. The wind energy can be divided in two categories; onshore and offshore wind energy. Offshore wind energy has many advantages in comparison with onshore but comes with a major disadvantage, the installation cost. Since installing an offshore wind turbine is far more complex than installing the same wind turbine onshore, different ways needs to be developed to compensate for the excess costs.
Even though the cost is a significant aspect, it is not the most critical one. Since
more power is required, bigger offshore wind turbines are needed, thus larger foundation structures and bigger water depths. The conventional Jack-Up Barge that was being used for such operations so far is driving to a saturation on its operability due to limitations on maximum crane capacity and maximum water depth. For the aforementioned reasons, a floating vessel is considered to install bigger foundations but this leads to the loss of fixed ground that the Jack-Up Barge provided. This creates a significant problem that motions are generated and disturb the installation process. For this reason, a compensating strategy should be developed to allow such installations.
Such solution comes from TWD with the Motion Compensating Pile Gripper. In order to reduce the installation costs and to allow installation of wind turbines in higher depths of water, a floating vessel has to be deployed instead of the conventional Jack-Up Barges. The use of a floating vessel though, generates motions that disturb the installation procedure. This is the reason that TWD came up with a compensating gripper. This gripper uses hydraulic cylinders to generate forces for the monopile and vessel in order to counteract unwanted motions and to keep the monopile in the required position.
In this thesis, initially a functional design is conducted. This analysis concludes with the possible design strategies that can restrict the monopile through the lowering operation. After the possible design strategies are established, a simulation model is generated that involves environmental loads, a vessel model, a monopile model and a gripper model.
Through that simulation model, the different alternatives are tested and imulated
in order to evaluate the performance of each and observe their responses. Finally, after all the alternatives are simulated, a Multi-Criteria Analysis takes place that evaluates each one of the possible strategies based on various criteria in order to conclude to the winning strategy that is then suggested to be implemented in the lowering operation of the monopile erection process. ... Read more