M.C. van Benten
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Sodium borohydride (NaBH4) is a promising hydrogen carrier for maritime applications due to its high gravimetric and volumetric energy densities compared to compressed or liquefied hydrogen. As a solid granular material, NaBH4 can be stored under atmospheric pressure and room temperature, eliminating the need for extreme pressures, or cryogenic conditions. Although NaBH4 is hygroscopic and can become cohesive when exposed to humid environments, when stored and handled sufficiently dry it remains free-flowing, which is essential for reliable conveying, storage, and discharge operations. Designing equipment for these processes requires an accurate understanding of NaBH4’s free-flowing behaviour, motivating the need for modelling tools. To address this, we model granular, free-flowing NaBH4 using the Discrete Element Method. Granular flow behaviour depends strongly on the flow regime—defined by the applied shear and confining pressure through the inertial number—and practical handling systems typically operate in the dense flow regime; consequently, this study focuses on dense-flow conditions. A standard calibration–verification–validation methodology is applied, using a ledge test and rotating drum for calibration and verification, and an inclined surface test for validation. In parallel, we evaluate the inertial number across all setups using a velocity-based approach to characterise both the global flow regime and locally occurring flow regimes within the flowing layer. Rather than assigning a single characteristic value per setup, we demonstrate that distinct segments exhibit different inertial numbers, indicating that the inertial number is spatially dependent.
...
Sodium borohydride (NaBH4) is a promising hydrogen carrier for maritime applications due to its high gravimetric and volumetric energy densities compared to compressed or liquefied hydrogen. As a solid granular material, NaBH4 can be stored under atmospheric pressure and room temperature, eliminating the need for extreme pressures, or cryogenic conditions. Although NaBH4 is hygroscopic and can become cohesive when exposed to humid environments, when stored and handled sufficiently dry it remains free-flowing, which is essential for reliable conveying, storage, and discharge operations. Designing equipment for these processes requires an accurate understanding of NaBH4’s free-flowing behaviour, motivating the need for modelling tools. To address this, we model granular, free-flowing NaBH4 using the Discrete Element Method. Granular flow behaviour depends strongly on the flow regime—defined by the applied shear and confining pressure through the inertial number—and practical handling systems typically operate in the dense flow regime; consequently, this study focuses on dense-flow conditions. A standard calibration–verification–validation methodology is applied, using a ledge test and rotating drum for calibration and verification, and an inclined surface test for validation. In parallel, we evaluate the inertial number across all setups using a velocity-based approach to characterise both the global flow regime and locally occurring flow regimes within the flowing layer. Rather than assigning a single characteristic value per setup, we demonstrate that distinct segments exhibit different inertial numbers, indicating that the inertial number is spatially dependent.
Journal article
(2025)
-
Nikos Kougiatsos, Evelien L. Scheffers, Marcel C. Van Benten, Dingena L. Schott, Peter De Vos, Rudy R. Negenborn, Vasso Reppa
Waterborne transport is very important for moving freight and passengers globally. To make this transport more efficient, vessel design must adapt to changing missions, regulations and the occurrence of malfunctions. This paper presents the design of an intelligent decision-support framework to assist marine engineers and vessel operators in updating the system and control architecture of marine vessels before and during a mission. The connection between the system architecture and control design perspectives is enabled using a semantics-based technique. To this end, the multi-level vessel control system is described by a semantic database, a knowledge graph used to connect the components automatically, and quantitative service criteria. Considering the system architecture, the optimal modification is deduced using modularity and complexity criteria, originating from the field of network theory. On the control side, an intelligent automation supervisor is designed to make offline and online decisions regarding the energy deficit to execute a new mission and the active automation configuration during operation. For offline decisions, system architecture modifications are requested by the vessel designers to cover the energy deficit. During operation, switching between hardware and virtual sensors as well as switching between energy management controllers is implemented to handle the effects of sensor faults. The framework is successfully applied to a case study of a tugboat used to adapt to missions with different power requirements, while simulation results are used to indicate its application in supporting the decisions of vessel designers and human vessel operators.
...
Waterborne transport is very important for moving freight and passengers globally. To make this transport more efficient, vessel design must adapt to changing missions, regulations and the occurrence of malfunctions. This paper presents the design of an intelligent decision-support framework to assist marine engineers and vessel operators in updating the system and control architecture of marine vessels before and during a mission. The connection between the system architecture and control design perspectives is enabled using a semantics-based technique. To this end, the multi-level vessel control system is described by a semantic database, a knowledge graph used to connect the components automatically, and quantitative service criteria. Considering the system architecture, the optimal modification is deduced using modularity and complexity criteria, originating from the field of network theory. On the control side, an intelligent automation supervisor is designed to make offline and online decisions regarding the energy deficit to execute a new mission and the active automation configuration during operation. For offline decisions, system architecture modifications are requested by the vessel designers to cover the energy deficit. During operation, switching between hardware and virtual sensors as well as switching between energy management controllers is implemented to handle the effects of sensor faults. The framework is successfully applied to a case study of a tugboat used to adapt to missions with different power requirements, while simulation results are used to indicate its application in supporting the decisions of vessel designers and human vessel operators.
Sodium borohydride (NaBH4) is increasingly considered as an alternative fuel for maritime vessels due to its relatively high energy density. When stored in dry solid form, it is a granular material, similar to coal, starch, and iron ore. As NaBH4 is historically used in the chemical industry in aqueous solutions, virtually no details regarding its behaviour as a solid granular material are known. Therefore, after determining particle properties such as size, shape, and density, this study characterises granular NaBH4 in three flow regimes using three experimental setups. Ring shear tests are used for the quasi-static regime, ledge tests for the dense flow regime, and rotating drum tests characterise both dense and gaseous flow, depending on the rotational speed. Various operational conditions, including temperature, humidity, time consolidation, and handling stresses, are taken into account. Experimental results demonstrate that above a threshold temperature and humidity, NaBH4 readily absorbs moisture from ambient air but remains free-flowing for most scenarios. However, time consolidation can transform this free-flowing material into a very cohesive substance. While this cohesiveness is reversible, requiring minimal agitation, the transformation from free-flowing to cohesive is accelerated by elevated moisture contents and a reduced particle size. Additionally, handling stresses were found to have minimal effect on the flow behaviour and characteristics of NaBH4. These findings are ultimately used to derive implications for the design of handling and storage equipment for NaBH4, enabling its use as an alternative fuel for maritime vessels.
...
Sodium borohydride (NaBH4) is increasingly considered as an alternative fuel for maritime vessels due to its relatively high energy density. When stored in dry solid form, it is a granular material, similar to coal, starch, and iron ore. As NaBH4 is historically used in the chemical industry in aqueous solutions, virtually no details regarding its behaviour as a solid granular material are known. Therefore, after determining particle properties such as size, shape, and density, this study characterises granular NaBH4 in three flow regimes using three experimental setups. Ring shear tests are used for the quasi-static regime, ledge tests for the dense flow regime, and rotating drum tests characterise both dense and gaseous flow, depending on the rotational speed. Various operational conditions, including temperature, humidity, time consolidation, and handling stresses, are taken into account. Experimental results demonstrate that above a threshold temperature and humidity, NaBH4 readily absorbs moisture from ambient air but remains free-flowing for most scenarios. However, time consolidation can transform this free-flowing material into a very cohesive substance. While this cohesiveness is reversible, requiring minimal agitation, the transformation from free-flowing to cohesive is accelerated by elevated moisture contents and a reduced particle size. Additionally, handling stresses were found to have minimal effect on the flow behaviour and characteristics of NaBH4. These findings are ultimately used to derive implications for the design of handling and storage equipment for NaBH4, enabling its use as an alternative fuel for maritime vessels.
To reduce global emissions, hydrogen is increasingly considered as an energy carrier for renewable energy storage. However, traditional storage methods for hydrogen such as compression or liquefaction require high pressures, extremely low temperatures, and still result in a low volumetric energy density. As a solution, sodium borohydride (NaBH4) is proposed as an alternative method to store hydrogen. NaBH4 is a granular material that can be stored using ambient temperature and pressure, and has a relatively high volumetric and gravimetric energy density compared to traditional hydrogen storage. This paper explores the application of NaBH4 as a fuel in the maritime industry, and elaborates on how the use of NaBH4 leads to a circular bunkering (refuelling) process. By using hydrolysis to extract hydrogen from NaBH4 during vessel operation, a so called spent fuel remains and needs to be stored on the vessel until next port call. Additionally, examples of various bunkering equipment that can be used to design the circular bunkering process of NaBH4 are presented. Moreover, it explains how design of bunkering equipment depends on the mechanical characteristics of the fuel and spent fuel. The main finding of this work is that NaBH4 is a promising solution for a sustainable future. Before NaBH4 can be used as a fuel, vessels and ports need to be adapted to facilitate circular bunkering with such a novel solid-state energy carrier.
...
To reduce global emissions, hydrogen is increasingly considered as an energy carrier for renewable energy storage. However, traditional storage methods for hydrogen such as compression or liquefaction require high pressures, extremely low temperatures, and still result in a low volumetric energy density. As a solution, sodium borohydride (NaBH4) is proposed as an alternative method to store hydrogen. NaBH4 is a granular material that can be stored using ambient temperature and pressure, and has a relatively high volumetric and gravimetric energy density compared to traditional hydrogen storage. This paper explores the application of NaBH4 as a fuel in the maritime industry, and elaborates on how the use of NaBH4 leads to a circular bunkering (refuelling) process. By using hydrolysis to extract hydrogen from NaBH4 during vessel operation, a so called spent fuel remains and needs to be stored on the vessel until next port call. Additionally, examples of various bunkering equipment that can be used to design the circular bunkering process of NaBH4 are presented. Moreover, it explains how design of bunkering equipment depends on the mechanical characteristics of the fuel and spent fuel. The main finding of this work is that NaBH4 is a promising solution for a sustainable future. Before NaBH4 can be used as a fuel, vessels and ports need to be adapted to facilitate circular bunkering with such a novel solid-state energy carrier.
The maritime sector accounts for approximately 3% of the global emissions, and to limit these emissions, a transition towards alternative fuels is ongoing. In this work, a novel circular bunkering process for marine vessels is considered, such that a renewable fuel economy for the maritime industry can be realised. The proposed bunkering process is shown in Figure 1, and uses sodium borohydride (NaBH4) as the fuel, due to its favourable gravimetric and volumetric energy density compared to other alternatives [1]. NaBH4 is fed into a reactor during vessel operation, where it reacts with water to form hydrogen and sodium metaborate (NaBO2). While the hydrogen can be used in e.g. fuel cells to power the ship, the NaBO2, also referred to as spent fuel, has to be stored for the remainder of the voyage. Both NaBH4 and NaBO2 are bulk solids with a particle size distribution ranging from a hundred micrometres to several millimetres.
To this moment, NaBH4 has predominantly been used in the chemical industry as a reducing agent [2], and consequently, the mechanical characteristics and the effects of operational conditions such as humidity, temperature, and stress on the behaviour of the material are virtually unknown. However, this knowledge is essential to be able to design the required storage and handling equipment to realise the aforementioned circular bunkering process. Therefore, this work focuses on acquiring the relevant data using experiments. While most experiments show that NaBH4 is initially free-flowing, particular combinations of operational conditions show a significant change in the materials flow characteristics, some results showing very cohesive material or even non-flowing characteristics. Using the acquired experimental data, the Discrete Element Method (DEM) will be used to calibrate, verify, and validate material models, such that the flow characteristics of this novel fuel can be captured numerically. These models can then be used to conceptualise the bunkering process in a virtual environment. Finally, an outlook on how to use the gained insights to develop and design the storage and handling equipment for the proposed circular bunkering process is presented.
References
[1]: M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023
[2]: Kaiqiang Zhang et al. “Recent Advances in the Nanocatalyst-Assisted NaBH 4 Reduction of Nitroaromatics in Water”. DOI: 10.1021/acsomega.8b03051
...
To this moment, NaBH4 has predominantly been used in the chemical industry as a reducing agent [2], and consequently, the mechanical characteristics and the effects of operational conditions such as humidity, temperature, and stress on the behaviour of the material are virtually unknown. However, this knowledge is essential to be able to design the required storage and handling equipment to realise the aforementioned circular bunkering process. Therefore, this work focuses on acquiring the relevant data using experiments. While most experiments show that NaBH4 is initially free-flowing, particular combinations of operational conditions show a significant change in the materials flow characteristics, some results showing very cohesive material or even non-flowing characteristics. Using the acquired experimental data, the Discrete Element Method (DEM) will be used to calibrate, verify, and validate material models, such that the flow characteristics of this novel fuel can be captured numerically. These models can then be used to conceptualise the bunkering process in a virtual environment. Finally, an outlook on how to use the gained insights to develop and design the storage and handling equipment for the proposed circular bunkering process is presented.
References
[1]: M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023
[2]: Kaiqiang Zhang et al. “Recent Advances in the Nanocatalyst-Assisted NaBH 4 Reduction of Nitroaromatics in Water”. DOI: 10.1021/acsomega.8b03051
...
The maritime sector accounts for approximately 3% of the global emissions, and to limit these emissions, a transition towards alternative fuels is ongoing. In this work, a novel circular bunkering process for marine vessels is considered, such that a renewable fuel economy for the maritime industry can be realised. The proposed bunkering process is shown in Figure 1, and uses sodium borohydride (NaBH4) as the fuel, due to its favourable gravimetric and volumetric energy density compared to other alternatives [1]. NaBH4 is fed into a reactor during vessel operation, where it reacts with water to form hydrogen and sodium metaborate (NaBO2). While the hydrogen can be used in e.g. fuel cells to power the ship, the NaBO2, also referred to as spent fuel, has to be stored for the remainder of the voyage. Both NaBH4 and NaBO2 are bulk solids with a particle size distribution ranging from a hundred micrometres to several millimetres.
To this moment, NaBH4 has predominantly been used in the chemical industry as a reducing agent [2], and consequently, the mechanical characteristics and the effects of operational conditions such as humidity, temperature, and stress on the behaviour of the material are virtually unknown. However, this knowledge is essential to be able to design the required storage and handling equipment to realise the aforementioned circular bunkering process. Therefore, this work focuses on acquiring the relevant data using experiments. While most experiments show that NaBH4 is initially free-flowing, particular combinations of operational conditions show a significant change in the materials flow characteristics, some results showing very cohesive material or even non-flowing characteristics. Using the acquired experimental data, the Discrete Element Method (DEM) will be used to calibrate, verify, and validate material models, such that the flow characteristics of this novel fuel can be captured numerically. These models can then be used to conceptualise the bunkering process in a virtual environment. Finally, an outlook on how to use the gained insights to develop and design the storage and handling equipment for the proposed circular bunkering process is presented.
References
[1]: M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023
[2]: Kaiqiang Zhang et al. “Recent Advances in the Nanocatalyst-Assisted NaBH 4 Reduction of Nitroaromatics in Water”. DOI: 10.1021/acsomega.8b03051
To this moment, NaBH4 has predominantly been used in the chemical industry as a reducing agent [2], and consequently, the mechanical characteristics and the effects of operational conditions such as humidity, temperature, and stress on the behaviour of the material are virtually unknown. However, this knowledge is essential to be able to design the required storage and handling equipment to realise the aforementioned circular bunkering process. Therefore, this work focuses on acquiring the relevant data using experiments. While most experiments show that NaBH4 is initially free-flowing, particular combinations of operational conditions show a significant change in the materials flow characteristics, some results showing very cohesive material or even non-flowing characteristics. Using the acquired experimental data, the Discrete Element Method (DEM) will be used to calibrate, verify, and validate material models, such that the flow characteristics of this novel fuel can be captured numerically. These models can then be used to conceptualise the bunkering process in a virtual environment. Finally, an outlook on how to use the gained insights to develop and design the storage and handling equipment for the proposed circular bunkering process is presented.
References
[1]: M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023
[2]: Kaiqiang Zhang et al. “Recent Advances in the Nanocatalyst-Assisted NaBH 4 Reduction of Nitroaromatics in Water”. DOI: 10.1021/acsomega.8b03051
Greenhouse gas emissions drive global warming, posing significant risks to ecosystems and human society. The maritime sector contributes approximately 3% of global emissions, leading the International Maritime Organization (IMO) to target a 40% reduction in emissions by 2030 and 70% by 2050, compared to 2008 levels. This reduction can be achieved by improving vessel efficiency or adopting alternative fuels such as hydrogen. Traditionally, hydrogen is stored as a gas, liquid, or cryocompressed, but these methods have drawbacks, including high pressure and energy demands. A promising alternative is sodium borohydride (NaBH4), a solid hydrogen carrier that offers high volumetric energy density and safe storage at ambient conditions. When used in maritime vessels, NaBH4 reacts with water to produce hydrogen and a byproduct, which is stored and later regenerated onshore. Both NaBH4 and its spent fuel are granular materials, requiring specific handling equipment. This paper aims to identify the mechanical characteristics of NaBH4 and its spent fuel to design appropriate storage and handling systems using the Discrete Element Method (DEM).
...
Greenhouse gas emissions drive global warming, posing significant risks to ecosystems and human society. The maritime sector contributes approximately 3% of global emissions, leading the International Maritime Organization (IMO) to target a 40% reduction in emissions by 2030 and 70% by 2050, compared to 2008 levels. This reduction can be achieved by improving vessel efficiency or adopting alternative fuels such as hydrogen. Traditionally, hydrogen is stored as a gas, liquid, or cryocompressed, but these methods have drawbacks, including high pressure and energy demands. A promising alternative is sodium borohydride (NaBH4), a solid hydrogen carrier that offers high volumetric energy density and safe storage at ambient conditions. When used in maritime vessels, NaBH4 reacts with water to produce hydrogen and a byproduct, which is stored and later regenerated onshore. Both NaBH4 and its spent fuel are granular materials, requiring specific handling equipment. This paper aims to identify the mechanical characteristics of NaBH4 and its spent fuel to design appropriate storage and handling systems using the Discrete Element Method (DEM).
Sodium borohydride (NaBH4) is considered as an alternative fuel for the maritime industry [1]. In contrast to conventional fuels, NaBH4 is a granular material. To use a simulation-supported design for assessing the feasibility of equipment designs for storing and handling this material, its mechanical characteristics are required. These are then used to calibrate and verify simulations using the Discrete Element Method (DEM). However, as this is a novel application for this material, virtually no bulk characteristics are known yet. Therefore extensive testing has been done to extract required mechanical characteristics, such as cohesion, adhesion, internal friction, wall friction, and the Angle of Repose (AoR). These experiments showed that NaBH4 is initially free-flowing, but an increase in the moisture content because of an increase in relative humidity leads to an increase in cohesion, effectively reducing the flowability of the bulk material. Furthermore, our experimental results showed plastic deformation of individual NaBH4 particles.
This work focuses on capturing both the free-flowing and cohesive behaviour of NaBH4 in DEM. To this end, the two-step calibration approach introduced by Grima [2] is adopted and adjusted. First, the free-flowing behaviour is calibrated using a non-cohesive contact model, Hertz-Mindlin (HM). Second, the cohesive material is calibrated using the appropriate cohesive parameters of the Edinburgh Elasto-Plastic Adhesion contact model (EEPA), while the (calibrated) non-cohesive parameters are kept constant. The novelty of this work is the use of EEPA for the second calibration step, which allows the modelling of both the cohesive behaviour and the plastic deformation of the individual particles in the bulk material.
[1] M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023.
[2] A. Grima. “Quantifying and modelling mechanisms of flow in cohesionless and cohesive granular materials”. In: University of Wollongong Thesis Collection 1954- 2016 (Jan. 2011). ...
This work focuses on capturing both the free-flowing and cohesive behaviour of NaBH4 in DEM. To this end, the two-step calibration approach introduced by Grima [2] is adopted and adjusted. First, the free-flowing behaviour is calibrated using a non-cohesive contact model, Hertz-Mindlin (HM). Second, the cohesive material is calibrated using the appropriate cohesive parameters of the Edinburgh Elasto-Plastic Adhesion contact model (EEPA), while the (calibrated) non-cohesive parameters are kept constant. The novelty of this work is the use of EEPA for the second calibration step, which allows the modelling of both the cohesive behaviour and the plastic deformation of the individual particles in the bulk material.
[1] M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023.
[2] A. Grima. “Quantifying and modelling mechanisms of flow in cohesionless and cohesive granular materials”. In: University of Wollongong Thesis Collection 1954- 2016 (Jan. 2011). ...
Sodium borohydride (NaBH4) is considered as an alternative fuel for the maritime industry [1]. In contrast to conventional fuels, NaBH4 is a granular material. To use a simulation-supported design for assessing the feasibility of equipment designs for storing and handling this material, its mechanical characteristics are required. These are then used to calibrate and verify simulations using the Discrete Element Method (DEM). However, as this is a novel application for this material, virtually no bulk characteristics are known yet. Therefore extensive testing has been done to extract required mechanical characteristics, such as cohesion, adhesion, internal friction, wall friction, and the Angle of Repose (AoR). These experiments showed that NaBH4 is initially free-flowing, but an increase in the moisture content because of an increase in relative humidity leads to an increase in cohesion, effectively reducing the flowability of the bulk material. Furthermore, our experimental results showed plastic deformation of individual NaBH4 particles.
This work focuses on capturing both the free-flowing and cohesive behaviour of NaBH4 in DEM. To this end, the two-step calibration approach introduced by Grima [2] is adopted and adjusted. First, the free-flowing behaviour is calibrated using a non-cohesive contact model, Hertz-Mindlin (HM). Second, the cohesive material is calibrated using the appropriate cohesive parameters of the Edinburgh Elasto-Plastic Adhesion contact model (EEPA), while the (calibrated) non-cohesive parameters are kept constant. The novelty of this work is the use of EEPA for the second calibration step, which allows the modelling of both the cohesive behaviour and the plastic deformation of the individual particles in the bulk material.
[1] M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023.
[2] A. Grima. “Quantifying and modelling mechanisms of flow in cohesionless and cohesive granular materials”. In: University of Wollongong Thesis Collection 1954- 2016 (Jan. 2011).
This work focuses on capturing both the free-flowing and cohesive behaviour of NaBH4 in DEM. To this end, the two-step calibration approach introduced by Grima [2] is adopted and adjusted. First, the free-flowing behaviour is calibrated using a non-cohesive contact model, Hertz-Mindlin (HM). Second, the cohesive material is calibrated using the appropriate cohesive parameters of the Edinburgh Elasto-Plastic Adhesion contact model (EEPA), while the (calibrated) non-cohesive parameters are kept constant. The novelty of this work is the use of EEPA for the second calibration step, which allows the modelling of both the cohesive behaviour and the plastic deformation of the individual particles in the bulk material.
[1] M.C. van Benten, J.T. Padding, and D.L. Schott. “Towards Hydrogen-Fuelled Marine Vessels using Solid Hydrogen Carriers”. In: The 14th International Conference on Bulk Materials Storage, Handling and Transportation. Wollongong, Australia, July 2023.
[2] A. Grima. “Quantifying and modelling mechanisms of flow in cohesionless and cohesive granular materials”. In: University of Wollongong Thesis Collection 1954- 2016 (Jan. 2011).
Solid hydrogen carriers, such as sodium borohydride or potassium borohydride, are considered promising options to enable the use of hydrogen as a fuel for marine vessels, because of their favourable gravimetric and volumetric energy density compared to compressed or liquefied hydrogen. When using solid hydrogen carriers, in the form of granules or powder, as fuel for marine vessels, a ’spent fuel’ forms which has to be stored on the vessel for the remainder of the voyage. The spent fuel has to be regenerated upon arrival at the destination port to achieve circularity. From an operational perspective, both the fuel and the spent fuel have to be stored for at least the duration of one vessel trip. To design the required storage and handling equipment to realize a circular bunkering process, the mechanical characteristics of both the fuel and the spent fuel e.g. particle size distribution, internal friction, cohesion, wall-friction, and flowability are required. However, little is known about these mechanical characteristics. Consequently, this paper aims to identify the relevant mechanical characteristics of solid hydrogen carriers in the context of bunkering marine vessels. Therefore, an extensive experimental plan using, amongst others, a ring shear tester and a ledge test is presented together with preliminary results of mechanical characteristics including time consolidation effects. The paper concludes with an outlook on the use of the results in DEM-supported design for storage and handling equipment, both onboard the vessel and in the port.
...
Solid hydrogen carriers, such as sodium borohydride or potassium borohydride, are considered promising options to enable the use of hydrogen as a fuel for marine vessels, because of their favourable gravimetric and volumetric energy density compared to compressed or liquefied hydrogen. When using solid hydrogen carriers, in the form of granules or powder, as fuel for marine vessels, a ’spent fuel’ forms which has to be stored on the vessel for the remainder of the voyage. The spent fuel has to be regenerated upon arrival at the destination port to achieve circularity. From an operational perspective, both the fuel and the spent fuel have to be stored for at least the duration of one vessel trip. To design the required storage and handling equipment to realize a circular bunkering process, the mechanical characteristics of both the fuel and the spent fuel e.g. particle size distribution, internal friction, cohesion, wall-friction, and flowability are required. However, little is known about these mechanical characteristics. Consequently, this paper aims to identify the relevant mechanical characteristics of solid hydrogen carriers in the context of bunkering marine vessels. Therefore, an extensive experimental plan using, amongst others, a ring shear tester and a ledge test is presented together with preliminary results of mechanical characteristics including time consolidation effects. The paper concludes with an outlook on the use of the results in DEM-supported design for storage and handling equipment, both onboard the vessel and in the port.
This paper presents the design methodology of a mission-oriented modular control system for marine power plants. To this end, first power profiles, power plant layouts and control systems of multiple vessels such as tugboats, offshore support vessels, cargo ships and cruise ships are analyzed. By decomposing the power profile in two components, the propulsion and auxiliary power demand, the correlation between the power profile of a vessel and its mission is derived, and an algorithm that computes the power profile using mission and vessel data is proposed. Furthermore, the correlation between the power profile and the layout of the power plant is also investigated, with emphasis on how changes in the power profile result in power plant automation modifications. A modular secondary control level is then designed to cope with the required power plant automation modifications, by combining the Equivalent Consumption Minimization Strategy (ECMS) with Supervisory Switching Control (SSC). In this paper we consider battery modifications, following the example of Wärtsilä's ZESPacks. Simulation results are used to show the performance of the proposed switching control methodology, in relation to the stability of the components in the power plant after automation modifications occur. The main contribution of this paper is the novel approach for the secondary level power plant control system, introducing modularity to the otherwise assumed fixed layout of the power plant. Furthermore, the proposed algorithm can be used to determine the expected power profile for a new mission, and to identify required modifications of the power plant equipment.
...
This paper presents the design methodology of a mission-oriented modular control system for marine power plants. To this end, first power profiles, power plant layouts and control systems of multiple vessels such as tugboats, offshore support vessels, cargo ships and cruise ships are analyzed. By decomposing the power profile in two components, the propulsion and auxiliary power demand, the correlation between the power profile of a vessel and its mission is derived, and an algorithm that computes the power profile using mission and vessel data is proposed. Furthermore, the correlation between the power profile and the layout of the power plant is also investigated, with emphasis on how changes in the power profile result in power plant automation modifications. A modular secondary control level is then designed to cope with the required power plant automation modifications, by combining the Equivalent Consumption Minimization Strategy (ECMS) with Supervisory Switching Control (SSC). In this paper we consider battery modifications, following the example of Wärtsilä's ZESPacks. Simulation results are used to show the performance of the proposed switching control methodology, in relation to the stability of the components in the power plant after automation modifications occur. The main contribution of this paper is the novel approach for the secondary level power plant control system, introducing modularity to the otherwise assumed fixed layout of the power plant. Furthermore, the proposed algorithm can be used to determine the expected power profile for a new mission, and to identify required modifications of the power plant equipment.