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Item type:Publication, Access status: with files , A comparison of the toxicity and asphyxiation risk during bunkering of LH2, LNG and NH3 by means of a quantitative risk assessmentTo achieve the greenhouse gas (GHG) reduction goals set by the International Maritime Organization (IMO), hydrogen, natural gas and ammonia are considered as marine fuel in their liquefied form. Nevertheless, concerns regarding their safety have been raised. Thus, the overarching aim of this investigation is it to addresses these concerns by conducting a comparative analysis of the safety of bunkering these fuels, with a particular focus on toxicity and asphyxiation hazards. A quantitative risk assessment is thus conducted in two steps: first, to identify the probability through a frequency analysis and second, to identify the severity through a consequence analysis. The present study will utilize the requisite safety distance as the threshold for the severity. The calculation of the safety distance necessary for the different fuels is performed utilizing a Gaussian dispersion model. Subsequently, both the necessary safety distance and the frequency of harmful events of all three fuels are then compared. The findings indicate that the frequencies of the toxicity/asphyxiation case are of comparable order magnitude for all fuels. However, the safety distance of ammonia is one order of magnitude larger than that of the other fuels.Publicationtype: Journal Article10 8 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Comparing the safety of bunkering LH2 and LNG using quantitative risk assessment with a focus on ignition hazards—Sensitivity analysisHydrogen, in its various storage forms, represents a potential fuel for climate-neutral shipping. In order to evaluate the safety of bunkering liquid hydrogen and to establish a basis for a comparison with the bunkering of LNG, a quantitative risk assessment has been conducted. This paper continues this work, by first realizing a quantitative risk assessment (QRA) with adopted systems allowing for the same bunkering duration for both fuels. The investigation shows that the diameter of the pipe has a significant impact on the frequency of hazardous events. To gain a deeper understanding of the effect, a sensitivity analysis is conducted. In addition to the frequencies, a notable impact of the pipe diameter can also be observed with regards to the safety distance in the full rupture case. Furthermore, the safety distances are found to be significantly impacted by wind speed and release time. The ambient temperature and humidity are identified to have only a minor impact.Publicationtype: Journal Article15 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Preheating options for novel design concepts for metal hydride storage tanks – Numerical modeling, simulation and evaluation(2025-06); ; ; ; Publicationtype: Conference Poster52 16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Novel concepts for metal hydride storage tanks – numerical modeling, simulation and evaluation(Elsevier, 2025-01-31); ; ; ; The efficient, space-saving and safe storage of hydrogen is a major challenge that needs to be overcome for enabling renewable energy systems. Metal hydrides are a possible solution. But the key challenge is the identification and development of the most promising metal hydride material as well as the ideal tank design for an efficient hydrogen absorption / desorption in terms of energy demand / storage losses and loading / unloading time. Against this background this paper aims to identify suitable combinations of medium and low-temperature metal hydride materials in combination with three different tank design concepts. The goal is to determine which material fits best for each combination and could thus be a suitable solution for a future implementation in stationary and mobile applications of metal hydride storage tanks. To achieve this goal a finite element method (FEM) modeling and simulation of materials and construction designs in COMSOL Multiphysics is realized. The results are analyzed in terms of hydrogen absorption rate, temperature profile over time, and the necessary energy demand for the overall storage process. The results show that for the low-temperature metal hydride investigated here, the tank design is of subordinate importance, allowing for more application-specific design. For medium-temperature metal hydrides, the investigated construction concepts show heterogeneous results. For fast hydrogen absorption and minimal external heating time, the suggested rectangular tank design might be a promising option, requiring only 28% / 29% of the heating energy of the cylindrical concepts. If the goal is to achieve the most complete hydrogen absorption, the base design concept investigated here, consisting of a cylindrical tank with metal hydride material rolled up in a spiral, is the most favorable solution; achieving a hydrogen loading of about 3.6 wt–% for the medium-temperature metal hydride. The low-temperature metal hydride achieves a total hydrogen absorption of around 1.4 wt-% in the optimum concept. For concepts with higher operating temperatures, preheating the storage tank before feeding in the hydrogen could improve the absorption process (only examined here).Publicationtype: Journal Article41 42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Poster: Development of a Hydrogen Metal Hydride Storage Produced by Additive Manufacturing(2023-07); ; ; ; Hydrogen as an energy carrier is attributed considerable importance in reduction of carbon dioxide emissions worldwide and transformation of the current economy to a low-carbon one. Production, storage, transportation and application of hydrogen are the key steps in the life cycles of hydrogen. It is desirable to increase the efficiency in any of these steps as well as enhance functionality of the systems. Hydrogen metal hydride storages (HMHS) can be used to store hydrogen at relatively low pressures while being relatively compact in size. Apart from using them for immobile systems they were also found to be beneficial in hydrogen-powered submarines or hydrogen-powered fork lifts. Additive manufacturing (AM) offers great potential for the simple and direct production of complex and functional components made of polymers and metals. Due to the freedom of design, AM offers great innovation potential compared to conventional anufacturing processes. In many cases, component designs that exploit the possibilities of AM show higher technical performance or functionality compared to components manufactured by conventional processes. This work assesses how the freedom of design due to laser powder bed fusion of metals (PBF-LB/M) as an additive manufacturing technique can be utilized for HMHS with better functionality than conventionally manufactured ones. The development of the component design was done using a morphological box. The final design incorporates secondary heat transfer surfaces that are inspired by heat transfer topology optimization. It is made in compact rectangular prism form that is in contrast to conventionally manufactured HMHS which commonly are cylindrical in shape. The design shows great potential for fast loading and customized outer dimensions of the tank to allow for more flexibility in the overall system design.Publicationtype: Conference Poster63 61 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Development of a Hydrogen Metal Hydride Storage Produced by Additive Manufacturing(2023-07); ; ; ; Hydrogen as an energy carrier is attributed considerable importance in reduction of carbon dioxide emissions worldwide and transformation of the current economy to a low-carbon one. Production, storage, transportation and application of hydrogen are the key steps in the life cycles of hydrogen. It is desirable to increase the efficiency in any of these steps as well as enhance functionality of the systems. Hydrogen metal hydride storages (HMHS) can be used to store hydrogen at relatively low pressures while being relatively compact in size. Apart from using them for immobile systems they were also found to be beneficial in hydrogen-powered submarines or hydrogen-powered fork lifts. Additive manufacturing (AM) offers great potential for the simple and direct production of complex and functional components made of polymers and metals. Due to the freedom of design, AM offers great innovation potential compared to conventional manufacturing processes. In many cases, component designs that exploit the possibilities of AM show higher technical performance or functionality compared to components manufactured by conventional processes. This work assesses how the freedom of design due to laser powder bed fusion of metals (PBF-LB/M) as an additive manufacturing technique can be utilized for HMHS with better functionality than conventionally manufactured ones. The development of the component design was done using a morphological box. The final design incorporates secondary heat transfer surfaces that are inspired by heat transfer topology optimization. It is made in compact rectangular prism form that is in contrast to conventionally manufactured HMHS which commonly are cylindrical in shape. The design shows great potential for fast loading and customized outer dimensions of the tank to allow for more flexibility in the overall system design.Publicationtype: Conference Paper181 395 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , 135 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Metallhydrid-Verbundwerkstoffe zur Wasserstoffspeicherung -- Konstruktion, Simulation, Versuch und Bewertung(2019-02)Publicationtype: Conference Presentation97 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Temperature distribution in a new composite material for hydrogen storage : design study of different cooling conceptsA newly developed composite material has been explored based on metal hydrides in combination with polymers enriched with highly porous carbon. As metal hydride, a RHC (reactive hydride composite) was chosen (e.g., MgH2 + 2 LiBH4). The hydride is infiltrated into the pores of the porous carbon suppressing the long-range phase separation of the two different hydrides by nano-confinement. The aim is to maintain fast kinetics and achieve cycle stability of the RHC (reactive hydride composite). The combination of RHC and porous carbon is then integrated into a polymer film to allow an easy and safe handling of the material. To produce a storage system out of such a film, the thin material is rolled in the same style like a rolled membrane module; i.e., it is rolled together with a thin spacer (e.g., steel mesh) allowing an easy hydrogen access to all parts of the membrane. The last step is the implementation of the rolled storage module into the tank shell. To analyze different design concepts and the behavior of this newly developed composite storage material, extensive FEM-simulations have been realized for different cooling structures. The latter is necessary to fulfil the thermodynamic requirements and to maximize the speed of hydrogen storage. Therefore, the temperature development within the storage during hydrogen feeding are investigated. Beside this, the hydrogen flow as well as the kinetics of the chemical reaction are analyzed. Based on such extensive simulations of different design concepts, the most promising overall storage systems are developed and systematically optimized. Finally, the total hydrogen content of the overall storage system is calculated and compared between different design concepts. Based on this, conclusions are drawn about robust criteria how to construct a cooling and heating device for this new storage material.Publicationtype: Conference Paper155 190 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Hydrogen storage for mobile application: Technologies and their assessment(2018-01-01); In post fossil energy systems, hydrogen may gain significant importance as a secondary energy carrier, especially for transportation purposes. This widely published statement is justified by the fact that hydrogen can be produced from fluctuating electricity provided, for example, by wind turbines or photovoltaic systems. The hydrogen provision depends on the availability of electrical energy and is then stored to be used depending on the given demand. However, the efficient storage of hydrogen as an energy carrier is challenging from a techno-economic point of view, for example, due to the low volumetric energy density of hydrogen under standard conditions as well as other challenging properties. Especially for mobile applications (e.g., cars, trucks, ships, trains) it is very important to have hydrogen storage options with high volumetric and gravimetric energy densities to allow highly efficient use and to be fully competitive compared to other options possible within the transportation sector. Thus, in recent years, various storage technologies and concepts have been developed to achieve this challenging goal. The three most widely developed options are high-pressure storage tanks, storage as liquid hydrogen, and storage of the hydrogen gas in metal hydride. But there are also other possibilities and ideas to allow hydrogen storage for mobile applications, such as liquid organic hydrogen carriers (LOHC), activated carbon, Metal-Organic-Frameworks (MOFs), and others. Against this background, the overall goal of this chapter is to describe the various possibilities to store hydrogen for mobile applications. This is realized based on physical and chemical principles as well as the current state of the technology. Additionally, ongoing developments and possible technological breakthroughs are outlined. Besides this, each option is characterized by comparable key figures (e.g., storage density, storage efficiency) for the current state of technology to allow an easy and transparent comparison. Additionally, the hydrogen storage systems discussed are compared to the target values of the DOE (US Department of Energy), which defines internationally accepted goals for the energy density and the costs of hydrogen storage. Finally, the various options are compared to each other. Based on this, statements are made defining which storage option under which frame condition can play which role at which point in time.Publicationtype: Book Part97