Italy
Enhancing Safety of Liquid and Vaporised Hydrogen Transfer Technologies in Public Areas for Mobile Applications
Sep 2023
Publication
Federico Ustolin,
Donatella Cirrone,
Vladimir V. Molkov,
Dmitry Makarov,
Alexandros G. Venetsanos,
Stella G. Giannissi,
Giordano Emrys Scarponi,
Alessandro Tugnoli,
Ernesto Salzano,
Valerio Cozzani,
Daniela Lindner,
Birgit Gobereit,
Bernhard Linseisen,
Stuart J. Hawksworth,
Thomas Jordan,
Mike Kuznetsov,
Simon Jallais and
Olga Aneziris
International standards related to cryogenic hydrogen transferring technologies for mobile applications (filling of trucks ships stationary tanks) are missing and there is lack of experience. The European project ELVHYS (Enhancing safety of liquid and vaporized hydrogen transfer technologies in public areas for mobile applications) aims to provide indications on inherently safer and efficient cryogenic hydrogen technologies and protocols in mobile applications by proposing innovative safety strategies which are the results of a detailed risk analysis. This is carried out by applying an inter-disciplinary approach to study both the cryogenic hydrogen transferring procedures and the phenomena that may arise from the loss of containment of a piece of equipment containing hydrogen. ELVHYS will provide critical inputs for the development of international standards by creating inherently safer and optimized procedures and guidelines for cryogenic hydrogen transferring technologies thus increasing their safety level and efficiency. The aim of this paper is twofold: present the state of the art of liquid hydrogen transfer technologies by focusing on previous research projects such as PRESLHY and introduce the objectives and methods planned in the new EU project ELVHYS.
A Model for Assessing the Risk of Liquid Hydrogen Transport through Road Tunnels
Sep 2023
Publication
Among the new energy carriers aimed at reducing greenhouse gas emissions the use of hydrogen is expected to grow significantly in various applications and sectors (i.e. industrial commercial transportation etc.) due to its high energy content by weight and zero carbon emissions. The increasingly widespread use of hydrogen will require massive distribution from production sites to final consumers and the delivery by means of liquid hydrogen road tankers may be a suitable cost-effective option for market penetration in the short-medium term. Liquid hydrogen (LH2) presents different hazards compared to gaseous hydrogen and an accidental release in confined spaces such as road tunnels might lead to the formation of a flammable hydrogen cloud that might deflagrate or even detonate. Nevertheless the potential negative effects on users in the event of accidental leakage of liquid hydrogen from a tanker in road tunnels so far have not been sufficiently investigated. Therefore a 3D Computational Fluid Dynamics model for the release of LH2 and its dispersion within a road tunnel was developed in this study. The proposed model was validated by a comparison with certain experimental and numerical studies found in the literature. Such modeling is demanding for long tunnels. Therefore the results of the simulations (e.g. the amount of hydrogen contained within the cloud) were combined with established simplified consequence methods to estimate the overpressures generated from a potential hydrogen deflagration. This was then used to evaluate the effects on users while evacuating from the tunnel. The findings showed that the worst scenario is when the release is in the middle of the tunnel length and the ignition occurs 90 s after the leakage.
Risk Management in a Containerized Metal Hydride Storage System
Sep 2023
Publication
HyCARE project supported by the Clean Hydrogen Partnership of the European Union deals with a prototype of hydrogen storage tank using a solid-state hydrogen carrier. Up to 40 kilograms of hydrogen are stored in twelve tanks at less than 50 barg and less than 100 °C. The innovative design is based on a standard twenty-foot container including twelve TiFe-based metal hydride (MH) hydrogen storage tanks coupled with a thermal energy storage in phase change materials (PCM). This article aims at showing the main risks related to hydrogen storage in a MH system and the safety barriers considered based on HyCARE’s specific risk analysis.<br/>Regarding the TiFe MH material used to store hydrogen experimental tests showed that the exposure of the MH to air or water did not cause spontaneous ignition. Furthermore an explosion within the solid MH cannot propagate due to internal pore size. Additionally in case of leakage the speed of hydrogen desorption from the MH is self-limited which is an important safety characteristic since it reduces the potential consequences from the hydrogen release scenario.<br/>Regarding the integrated system the critical scenarios identified during the risk analysis were: explosion due to release of hydrogen inside or outside the container internal explosion inside MH tanks due to accidental mix of hydrogen and air and asphyxiation due to inert gas accumulation in the container. This identification phase of the risk analysis allowed to pinpoint the most relevant safety barriers already in place and recommend additional ones if needed to further reduce the risk that were later implemented.<br/>The main safety barriers identified were: material and component selection (including the MH selected) safety interlocks safety valves ventilation gas detection and safety distances.<br/>The risk management process based on risk identification and assessment contributed to coherently integrate inherently safe design features and safety barriers.
Computational Fluid Dynamic (CFD) Analysis of a Cold-adsorbed Hydrogen Tank During Refilling
Sep 2023
Publication
Hydrogen has the potential to be an important source of clean energy but the development of efficient and cost-effective methods for storing hydrogen is a key challenge that needs to be addressed in order to make widespread use of hydrogen as a possible energy sourc. There are different methods for storing hydrogen (i.e. compressed it at high pressures liquefied by cooling the hydrogen to a temperature of -253°C and stored with a chemical compound) each with its own advantages and disadvantages.<br/>MAST3RBoost (Maturing the Production Standards of Ultraporous Structures for High Density Hydrogen Storage Bank Operating on Swinging Temperatures and Low Compression) is a European project which aims to provide a solid benchmark of cold-adsorbed H2 storage (CAH2) at low compression (100 bar or below) by maturation of a new generation of ultraporous materials for mobility applications i.e. H2-powered vehicles including road and railway air-borne and waterborne transportation. Based on a new generation of Machine Learning-improved ultraporous materials – such as Activated Carbons (ACs) and high-density MOFs (Metal-organic Frameworks) – MAST3RBoost project will enable a disruptive path to meet the industry goals by developing the first worldwide adsorption-based demonstrator at the kg-scale.<br/>The design of the tank is supported by numerical investigation by mean of the use of Computational Fluid Dynamic (CFD) commercial code. In this a paper a preliminary analysis of the refilling of tank is presented focused on the effect of different tank configurations on the hydrogen temperature and on the hydrogen adsorption.
Safety Aspects Related to the Underground Hydrogen Storage
Sep 2023
Publication
The transition from fossil fuels to the renewable energies (wind solar) is a key factor to face climate change and build a sustainable reliable and secure energy system. To balance the intermittent energy demand and supply affecting the renewable sources the surplus of electrical energy may be converted in hydrogen and then storage in geological formations. While the risks associated to the natural gas storage in the sub-surface are well known from decades those associated with hydrogen underground storage (UHS) are relatively underexplored. This paper presents an inventory of risks related to large H2-storage in depleted gas and oil fields salt caverns and aquifers. Different issues such as integrity and durability of materials H2 leakages and interaction with the reservoir H2 uncontrolled outflow from the wellhead with potential combustion of air-hydrogen mixture (fire and explosion) soil subsidence and induced seismicity are analyzed.
GT Enclosure Dispersion Analysis with Different CFD Tools
Sep 2023
Publication
A gas turbine is usually installed inside an acoustic enclosure where the fuel gas supply system is also placed. It is common practice using CFD analysis to simulate the accidental fuel gas release inside the enclosure and the consequent dispersion. These numerical studies are used to properly design the gas detection system according to specific safety criteria which are well defined when the fuel gas is a conventional natural gas. Package design is done to prevent that any sparking items and hot surfaces higher than auto-ignition temperature could be a source of ignition in case of leak. Nevertheless it is not possible to exclude that a leakage from a theoretical point of view could be ignited and for this reason a robust design requires that the enclosure structure is able to withstand the overpressure generated by a gas cloud ignition. Moving to hydrogen as fuel gas makes this design constraint much more relevant for its known characteristics of reactiveness large range of flammability maximum burning velocity etc. In such context gas leak and dispersion analysis become even more crucial because a correct prediction of these scenarios can guide the design to a safe configuration. The present work shows a comparison of the dispersion of different leakages inside a gas turbine enclosure carried out with two different CFD tools Ansys CFX and FLACS. This verification is considered essential since dispersion analysis results are used as initial conditions for gas cloud ignition simulations strictly necessary to predict the consequence in term of overpressure without doing experimental tests.
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