Risk and safety assessment of hydrogen pipelines and storage tanks using preliminary hazard analysis

<p indent=0mm>As a kind of important clean and renewable energy, hydrogen energy has received increasing attention. In the past, the majority of researchers from colleges and universities, Chinese Academy of Sciences and other institutions carrying out hydrogen energy related research were supported by the National Natural Science Foundation of China, Ministry of Science and Technology. Nowadays many enterprises are also involved, including both private enterprises and state owned enterprises. This is a significant shift in this research field that will further promote the development of hydrogen energy industry. Hydrogen industry includes hydrogen production, separation, storage and transportation, application and other links. Great strides have been made in these fields in recent years. Some of these fields are developing rapidly, while others are still facing many challenges. This paper makes a systematic analysis and induction of the status, issues and future development potential of the hydrogen industry chain. The paper is divided into seven parts, including hydrogen preparation, hydrogen storage, hydrogen transportation, hydrogen pipeline transportation, liquid hydrogen manufacturing, storage and transportation, hydrogen refueling station, conclusions and suggestions. In the part of hydrogen preparation, we introduce the methods of hydrogen preparation, separation and purification, the annual changes of world pure hydrogen and mixed hydrogen production, the relationship between hydrogen price of different hydrogen production methods and main raw material price, and the comparison of hydrogen production technologies and characteristics of different electrolytic water. In the part of hydrogen storage, four main methods: High-pressure gas hydrogen storage, low-temperature liquid hydrogen storage, solid hydrogen storage and organic liquid hydrogen storage are introduced, and the performances of these four methods are compared. In the part of hydrogen transportation, we introduce several common hydrogen transportation methods, the performance comparison of several common hydrogen transportation methods, and the price variance by distance of the three main hydrogen transportation methods. In the part of hydrogen pipeline transportation, the construction of two domestic hydrogen pipelines and the comparison of relevant parameters, as well as the situation of hydrogen transportation pipelines around the world are introduced. In the part of liquid hydrogen production, storage and transportation, the production methods of liquid hydrogen, the difference in calorific value between hydrogen fuel and other fuels, the preparation level of liquid hydrogen all over the world and the development direction in the future are introduced. In the part of hydrogenation stations, the construction, operation, cost and problems of hydrogenation refueling stations around the world are introduced. Finally, based on the contents above, we draw some conclusions and suggestions as follows: (1) In terms of hydrogen production, it is necessary to reduce the cost, develop hydrogen production from fossil raw materials to clean energy electrolytic water, focus on the development of proton exchange membrane green hydrogen preparation technology and enlarge its scale. (2) In terms of hydrogen storage, it is necessary to select appropriate hydrogen storage methods and improve their performance according to different applications. In the field of transportation, it is necessary to develop a hydrogen storage system with a weight density greater than 5wt% and a volume density greater than <sc>40 g/L,</sc> which is cost-effective and easy to control hydrogen absorption and desorption. In the non-transportation field, it is necessary to develop large-scale, low energy consumption and high safety hydrogen storage technology. (3) In terms of hydrogen transportation, it is necessary to strengthen the development of pipeline hydrogen transportation and liquid hydrogen transportation technology. (4) In terms of hydrogen refueling station, it is necessary to realize the localization of key equipment such as compressors and hydrogen injectors, improve the operation efficiency of hydrogen refueling stations and reduce the operational cost; Hydrogen production stations and liquid hydrogen refueling stations need to be developed.

The design and optimization of a cryogenic compressed hydrogen refueling process

Finite element simulation of heat and mass transfer in activated carbon hydrogen storage tank

Efficient hydrogen storage methods are crucial for the large-scale application of hydrogen energy. This work studied the effects of fin structure and injection tube on the system performance of a hydrogen storage tank packed with LaNi5 alloy. An axisymmetric finite element model of the metal hydride hydrogen storage tank was established. The fin structure and injection tube were added to the hydrogen storage tank, and the effects of the fin location and injection tube on the efficiency and safety of the hydrogen storage tank during hydriding were analyzed. A parametric study on the wall fin structure and injection tube has been carried out to optimize the design of a hydrogen storage tank, and to improve its efficiency and safety. The hydrogen storage capacity of the optimized tank packed with LaNi5 alloy can reach 1.312 wt%, which is 99% of its maximum capacity, at around 650 s. The results show that the fin structure can improve the heat transfer performance of the storage tank, and that the injection tube can enhance the mass transfer of hydrogen in the tank.

ABSTRACTEnvironmental problems arisen from burning fossil fuels results in the development of renewable resources for electric power production in the power networks, and electric and hydrogen vehicles in the transportation systems. Among the various renewable sources, wind and photovoltaic power plants have grown more and are widely used to supply loads, especially in microgrids. In this paper, optimal scheduling of a stand‐alone microgrid containing wind turbines, photovoltaic power plants and fuel‐based generation units is performed. Due to the variation in the wind speed and sun irradiance, the output power of wind turbines and photovoltaic power plants varies. To reduce uncertainty of output power of renewable resources, energy storage system such as electrolysis device‐ hydrogen tank‐ fuel cell device can be used in the stand‐alone microgrid. The hydrogen produced by electrolysis system is stored in the hydrogen tank. The stored hydrogen can be used in the fuel cell device for electric power generation or sold to the hydrogen vehicles. When, the generated power of renewable resources is less than the required load, the generated power of the fuel cell can compensate all or some of electric power shortage. Besides, the hydrogen vehicles can purchase the electric power stored in their batteries to the microgrid, and participate in the vehicle to microgrid scheme. In this paper, for optimal scheduling of the stand‐alone microgrid, operation cost of fuel‐based microgrid, the reliability cost associated to the penalty of load curtailment, the income from the sale of electricity and hydrogen and the cost of purchasing electricity from hydrogen vehicles are considered. To clearly investigate the impact of renewable resources, hydrogen storage system and hydrogen vehicles on the optimal scheduling of the stand‐alone microgrid, numerical outcomes of a microgrid simulated in the MATLAB software are given.

Hydrogen and gas storage tanks installed in facilities are typically vertical cylindrical structures made of steel. To allow for the discharge of stored materials, these tanks are anchored onto concrete blocks with sufficient height. However, this design results in a higher center of gravity, making the tanks more vulnerable to external forces such as earthquakes. This study fabricated a storage tank model and foundation concrete based on the results of the field investigation of the hydrogen storage tank. Then, an artificial earthquake was generated by referring to ICC-ES AC 156, a shaking table test method for non-structural elements. Experimenting on a full-scale structure is ideal; however, a storage tank model was fabricated and settled on the foundation concrete for tri-axial shaking table testing due to limited testing facilities and equipment performance. In the shaking table test, the presence or absence of water inside the storage tank was set as the condition for storing gases and liquids. The seismic behavior characteristics and failure mode of the storage tank model fixed in the foundation concrete were analyzed using the testing results. A seismic fragility curve was drawn up, and the high confidence and low probability of failure (HCLPF) was calculated.

Hydrogen has been considered as a feasible energy carry for fuel cell vehicles, which offers a clean and efficient alternative for transportation. In the currently developed hydrogen compression cycle system, hydrogen is compressed through a compressor and stored in the tank as high pressure. The hydrogen is filled from high pressure station into hydrogen storage system in fuel cell vehicles. In the study, theoretical and simulation are performed by presenting a mathematical model for the temperature rise during filling process in the hydrogen storage tank at the pressure of 50 MPa compressed hydrogen system. For a high-pressure tank (HPT) that can store hydrogen at a hydrogen filling station, the temperature rise of hydrogen with the pressure change during the filling process, the amount of hydrogen filling in the tank, and the convective heat transfer coefficient in the tank were calculated. The calculated temperature was compared with numerical and theoretical methods. Appropriate theoretical formulas were presented through mathematical modeling for changes that occur when high-pressure storage tanks were filled, and hydrogen properties were analyzed using the REFPROP program. 3D modeling was performed for the high-pressure storage tank, and the analysis was conducted under adiabatic conditions. When the pressure was increased to 50 MPa in the initial vacuum state, and when the residual pressure was 18 MPa, it was 25, 50, 75,and 100 MPa, and hydrogen inside the storage tank of the temperature rise and the amount of hydrogen filling were investigated. The results of this study will be useful for the design and construction of compressed hydrogen tank for hydrogen charging system.

Coupled thermal simulation of hydrogen storage tank-Dewar flask system

Development of regulations, codes and standards on composite tanks for on-board gaseous hydrogen storage

Hydrogen can be a promising option as an energy storage medium in renewable power generator‐based microgrid. However, the technologies used for the hydrogen storage such as high pressure in gaseous form and solid storages can significantly affect the cost performance of the hydrogen‐based microgrid. In this study, a techno‐economic assessment for solid hydrogen storage (metal hydride [MH])‐based microgrid in Indian operating conditions has been carried out in terms of levelized cost of electricity (LCOE), net present cost, and avoided environmental emissions. In the present microgrid, excess photovoltaic (PV) generator electricity is used to generate hydrogen using the alkaline water electrolyzer (EL). This generated hydrogen is stored in the MH cylinder. The stored hydrogen is converted back into electricity by fuel cell (FC) in case of insufficiency of PV electricity. The sizing of the microgrid components such as PV, FC, EL, and hydrogen storage tank are obtained for given load profile using HOMER optimization tool. An attempt has been made for the cost evaluation of the solid and high‐pressure gaseous storages in the microgrid. A comparative study between two energy storage mediums such as battery and hydrogen in microgrid is also performed. In case of battery and hydrogen storages, the LCOE is found to be 0.1293 and 0.383 $/kWh, respectively. It was found that battery storage system is more economical than hydrogen storage in microgrid. Nonetheless, the difference between the LCOE in hydrogen‐based microgrid is reduced considerably with optimized cost scenario of the EL, FC, and H2 storage tank as compared to the battery storage. Such technical, economic, and environmental assessment of the MH‐based microgrid system provides a firm basis to policymakers for shaping energy and environment policies for hydrogen activities.

With the rapid increase in the photovoltaic (PV) installations, the intermittency and the variability of the solar energy sources will lead to the frequent and steep ramping operation of conventional fossil generation. Consequently, energy storage is required for efficient use of the renewable energy source. Hydrogen production via electrolysis can provide both short and long duration capacity as a controllable load to reduce grid fluctuations and improve the resilience of the energy system. Once the hydrogen is produced, it must be stored before it is consumed. High pressure gaseous hydrogen storage is the most popular and mature hydrogen storage technology due to the technical simplicity, reliability, energy efficiency as well as affordability [1]. Compressed hydrogen storage with a fast filling-emptying rate can be used as a hydrogen multiple-purpose station for both stationary fuel cell and fuel cell electric vehicle (FCEV) applications. Although hydrogen electrolyzers, stationary fuel cells, and FCEV refueling stations have been extensively studied, little work has been done integrating these hydrogen technologies with a utility PV field to ensure electric grid stability, maximize PV utilization and efficiently produce and consume hydrogen. A model for a complete system of hydrogen production via electrolysis and high-pressure hydrogen storage was developed. The dynamic performance of different hydrogen storage filling and emptying operations with electrolyzer, stationary fuel cell and FCEV shows the feasibility and flexibility of the integrated hydrogen system.A high-fidelity dynamic model of a Proton Exchange Membrane (PEM) electrolyzer was developed for hydrogen production from PV electricity. A parallel multi-stage hydrogen compression system with cascade tanks for filling/emptying was designed and modeled. A non-adiabatic lumped dynamic model was developed for the storage tank with heat transfer from the tank to ambient air. The Soave-Redlich-Kwong equation of state was adopted to account for the non-ideal gas response of high-pressure gaseous hydrogen [2]. The 1 MW electrolyzer under full load produces hydrogen at 200 Nm3/hr (17.7 kg/hr) and the hydrogen can be compressed up to the maximum pressure of 45 MPa suitable for heavy-duty fuel cell vehicles.The storage tanks can be filled with constant/varied hydrogen flow from the electrolyzer depending on the PV power. The compressor and heat exchanger duties as well as the storage tank pressure and temperature are monitored and controlled. The tanks can be discharged to the stationary fuel cell and/or FCEVs. The dynamic performance of integrated hydrogen system for PV smoothing (filling with varied hydrogen flow in short time-scale), peak shaving (filling and emptying with constant hydrogen flow in long time-scale) and FCEV refueling (cascade filling and emptying) will be presented. The feasibility and flexibility of integrated hydrogen production and storage system for grid operation will be shown.[1] Li, Mengxiao, Yunfeng Bai, Caizhi Zhang, Yuxi Song, Shangfeng Jiang, Didier Grouset, and Mingjun Zhang. "Review on the research of hydrogen storage system fast refueling in fuel cell vehicle." International Journal of Hydrogen Energy 44, no. 21 (2019): 10677-10693.[2] Xiao, Lei, Jianye Chen, Yimei Wu, Wei Zhang, Jianjun Ye, Shuangquan Shao, and Junlong Xie. "Effects of pressure levels in three-cascade storage system on the overall energy consumption in the hydrogen refueling station." International Journal of Hydrogen Energy 46, no. 61 (2021): 31334-31345.

The hydrogen storage tank is a key parameter of the hydrogen storage system in hydrogen fuel cell vehicles (HFCVs), as its safety determines the commercialization of HFCVs. Compared with other types, the type IV hydrogen storage tank which consists of a polymer liner has the advantages of low cost, lightweight, and low storage energy consumption, but meanwhile, higher hydrogen permeability. A detailed review of the existing research on hydrogen permeability of the liner material of type IV hydrogen storage tanks can improve the understanding of the hydrogen permeation mechanism and provide references for following-up researchers and research on the safety of HFCVs. The process of hydrogen permeation and test methods are firstly discussed in detail. This paper then analyzes the factors that affect the process of hydrogen permeation and the barrier mechanism of the liner material and summarizes the prediction models of gas permeation. In addition to the above analysis and comments, future research on the permeability of the liner material of the type IV hydrogen storage tank is prospected.

To achieve carbon neutrality by 2050, significant progress is being made in developing 50,000 m3 liquefied hydrogen storage tanks. One of the primary design challenges for these tanks is fatigue caused by repeated refilling cycles and seismic events. The influence of welding residual stress on fatigue performance is a critical factor that cannot be overlooked. Given the cryogenic conditions under which these tanks operate, full-scale testing is essential to ensure their safety and reliability. In this study, low-cycle fatigue (LCF) tests were conducted at an extremely low temperature of 20 K on 316L stainless steel specimens. These specimens were specifically designed to replicate the corner configurations of liquefied hydrogen (LH2) storage tanks and included two types of welds for comparison. The test amplitude was determined based on a Level 2 earthquake, representing a significant earthquake that could compromise the structural integrity of the tank. Following the LCF tests, fracture surfaces were analyzed in detail using a scanning electron microscope (SEM) to estimate crack lengths and propagation rates. The results of these observations provided critical insights into the safety of the storage tanks, demonstrating their ability to withstand the operational stresses and environmental conditions they are expected to face during their service life.

4 - Adaptation to Security Vulnerability Analysis (SVA)

The relationship between thermal management methods and hydrogen storage performance of the metal hydride tank