Natural Gas Pipeline Transportation Research Articles

A novel optimization framework for natural gas transportation pipeline networks based on deep reinforcement learning

Natural gas is an emerging and reliable energy source in transition to a low-carbon economy. The natural gas transportation pipeline network systems are crucial when transporting natural gas from the production endpoints to processing or consuming endpoints. Optimizing the operational efficiency of compressor stations within pipeline networks is an effective way to reduce energy consumption and carbon emissions during transportation. This paper proposes an optimization framework for natural gas transportation pipeline networks based on deep reinforcement learning (DRL). The mathematical simulation model is derived from mass balance, hydrodynamics principles of gas flow, and compressor characteristics. The optimization control problem in steady state is formulated into a one-step Markov decision process (MDP) and solved by DRL. The decision variables are selected as the discharge ratio of each compressor. By the comprehensive comparison with dynamic programming (DP) and genetic algorithm (GA) in three typical element topologies (a linear topology with gun-barrel structure, a linear topology with branch structure, and a tree topology), the proposed method can obtain 4.60% lower power consumption than GA, and the time consumption is reduced by 97.5% compared with DP. The proposed framework could be further utilized for future large-scale network optimization practices.

Current Status and Analysis of Natural Gas Pipeline Hydrogen Blending and Transportation Development

Hydrogen doping in natural gas pipelines is one of the means to realize large-scale, long-distance and low-cost hydrogen transportation, but hydrogen doping in natural gas pipelines has brought about non-negligible impacts on pipeline operating conditions, safety and maintenance, etc., and has certain potential safety hazards. To this end, the technical research and engineering application of hydrogen doping in natural gas pipelines at home and abroad are discussed, and the main factors affecting the safe transportation of hydrogen doping in natural gas pipelines are discussed, i.e., physical changes of natural gas caused by hydrogen doping, hydrogen failure, and uneven mixing. The results show that the hydrogen doping of natural gas puts new requirements on the existing pipe materials, and relevant experiments need to be carried out in order to reveal the mechanism of hydrogen failure, and whether gas aggregation occurs after the shutdown of hydrogen-doped natural gas pipelines is closely related to whether hydrogen failure occurs in the pipelines or not. The above results clarify the risks of hydrogen-doped transportation, which can provide a reference for the promotion of large-scale hydrogen-doped mixing and transmission projects and practical operation.

Study of NO and CO Formation Pathways in Jet Flames with CH4/H2 Fuel Blends

The existing natural gas transportation pipelines can withstand a hydrogen content of 0 to 50%, but further research is still needed on the pathways of NO and CO production under moderate or intense low oxygen dilution (MILD) combustion within this range of hydrogen blending. In this paper, we present a computational fluid dynamics (CFD) simulation of hydrogen-doped jet flame combustion in a jet in a hot coflow (JHC) burner. We conducted an in-depth study of the mechanisms by which NO and CO are produced at different locations within hydrogen-doped flames. Additionally, we established a chemical reaction network (CRN) model specifically for the JHC burner and calculated the detailed influence of hydrogen content on the mechanisms of NO and CO formation. The findings indicate that an increase in hydrogen content leads to an expansion of the main NO production region and a contraction of the main NO consumption region within the jet flame. This phenomenon is accompanied by a decline in the sub-reaction rates associated with both the prompt route and NO-reburning pathway via CHi=0–3 radicals, alongside an increase in N2O and thermal NO production rates. Consequently, this results in an overall enhancement of NO production and a reduction in NO consumption. In the context of MILD combustion, CO production primarily arises from the reduction of CO2 through the reaction CH2(S) + CO2 ⇔ CO + CH2O, the introduction of hydrogen into the system exerts an inhibitory effect on this reduction reaction while simultaneously enhancing the CO oxidation reaction, OH + CO ⇔ H + CO2, this dual influence ultimately results in a reduction of CO production.

Detection of Harmful H2S Concentration Range, Health Classification, and Lifespan Prediction of CH4 Sensor Arrays in Marine Environments

Underwater methane (CH4) detection technology is of great significance to the leakage monitoring and location of marine natural gas transportation pipelines, the exploration of submarine hydrothermal activity, and the monitoring of submarine volcanic activity. In order to improve the safety of underwater CH4 detection mission, it is necessary to study the effect of hydrogen sulfide (H2S) in leaking CH4 gas on sensor performance and harmful influence, so as to evaluate the health status and life prediction of underwater CH4 sensor arrays. In the process of detecting CH4, the accuracy decreases when H2S is found in the ocean water. In this study, we proposed an explainable sorted-sparse (ESS) transformer model for concentration interval detection under industrial conditions. The time complexity was decreased to O (n logn) using an explainable sorted-sparse block. Additionally, we proposed the Ocean X generative pre-trained transformer (GPT) model to achieve the online monitoring of the health of the sensors. The ESS transformer model was embedded in the Ocean X GPT model. When the program satisfied the special instructions, it would jump between models, and the online-monitoring question-answering session would be completed. The accuracy of the online monitoring of system health is equal to that of the ESS transformer model. This Ocean-X-generated model can provide a lot of expert information about sensor array failures and electronic noses by text and speech alone. This model had an accuracy of 0.99, which was superior to related models, including transformer encoder (0.98) and convolutional neural networks (CNN) + support vector machine (SVM) (0.97). The Ocean X GPT model for offline question-and-answer tasks had a high mean accuracy (0.99), which was superior to the related models, including long short-term memory–auto encoder (LSTM–AE) (0.96) and GPT decoder (0.98).

Physics Constrained High-Precision Data-Driven Modeling for Multi-Path Ultrasonic Flow Meter in Natural Gas Measurement.

Ultrasonic flow meters are crucial measuring instruments in natural gas transportation pipeline scenarios. The collected flow velocity data, along with the operational conditions data, are vital for the analysis of the metering performance of ultrasonic flow meters and analysis of the flow process. In practical applications, high requirements are placed on the modeling accuracy of ultrasonic flow meters. In response, this paper proposes an ultrasonic flow meter modeling method based on a combination of data learning and industrial physics knowledge. This paper builds ultrasonic flow meter flow velocity prediction models under different working conditions, combining pipeline flow field velocity distribution knowledge for data preprocessing and loss function design. By making full use of the characteristics of the physics and data learning, the prediction results are close to the real acoustic path flow velocity distribution; thus, the model has high accuracy and interpretability. Experiments are conducted to prove that the prediction error of the proposed method can be controlled within 1%, which can meet the needs of ultrasonic flow meter modeling and subsequent performance analysis in actual production.

Investigation into flow-induced internal corrosion direct assessment in small-diameter dry gas fluctuating pipeline

Small-diameter undulating natural gas pipelines with low gas transmission capacity do not have internal inspection conditions to grasp the internal corrosion status of the pipeline. This study focuses on a small-diameter undulating dry natural gas gathering and transportation pipeline, the internal corrosion mechanism of the pipeline is studied through corrosion products, and the specific location of the internal corrosion sensitive pipe segment is determined based on multiphase flow simulation and PMDT(pipeline non-contact magnetic anomaly detection); the excavation inspection is ultimately used to evaluate the internal status of the pipeline. The results demonstrate that the internal corrosion mechanism of ZL (ZI Lai) pipeline is O2 and CO2 synergistic corrosion in which O2 plays a dominant role, while the increasing flow rate will aggravate corrosion; The maximum general corrosion rate and critical inclination along the pipeline are 0.0218 mm/a and 18.4°, respectively. Furthermore, twelve corrosion sensitive segments have been identified, including two II-level and six III-level magnetic anomaly segments. The internal corrosion defects are localized at the 3–9o’clock position of the pipeline, with a maximum general corrosion rate not exceeding 0.0228 mm/a. Furthermore, the pipeline failure pressure of 12.27 MPa surpasses the maximum allowable working pressure of 8.84 MPa, ensuring its continued operational safety. The corrosion protection measures of reducing the water content of natural gas, adding vapor corrosion inhibitor and regularly detecting magnetic anomaly pipeline are developed.

Research on Failure Pressure of API 5L X100 Pipeline with Single Defect

Background: With the continuous application of API 5L X100 high-strength grade steel pipeline and the development trend of increasing pipeline diameter and design pressure in China's long natural gas and petroleum pipeline, API 5L X100 high-strength grade steel pipeline steel is bound to become the aorta in long-distance pipeline construction in the future. Studying the failure pressure of API 5L X100 high-strength grade steel pipeline has high economic and social benefits. Objective: Exploring the corrosion mechanism of the two single corroded pipeline models with outer defect and inner defect. Methods: Using ANSYS Workbench 15.0 software to explore the two single corroded pipeline models with outer defect and inner defect and the influence of geometric parameters such as defect depth, defect length, defect width, etc., on the maximum equivalent stress and failure pressure investigated. Based on the finite element analysis database, the failure pressures of two single corroded pipeline models were fitted using Matlab software and the fitting formulas. Results: In the corrosion defect area of the pipeline, stress concentration occurs; Far away from the corrosion defect area, the stress distribution is uniform. For the pipeline model with outer defect and inner defect, as the defect depth and length increases, failure pressure shows a decreasing trend and is almost unaffected by defect width; As the ratio of diameter to thickness increases, failure pressure shows a decreasing trend; By fitting failure pressure formula of the pipeline models with outer defect and inner defect, a multivariate fitting function formula of failure pressure is obtained, with high fitting exactitude. Conclusion: The conclusion obtained have certain guiding values for the normal and stable operation of natural gas and petroleum transportation pipelines.

Experimental and model research on judging liquid accumulation in pipelines under the action of surfactant

Foam drainage gas extraction is applied in various natural gas extraction scenarios, such as water-bearing gas wells, gas fields with high water content, and wet natural gas pipeline transport, with the goal of enhancing extraction efficiency and lowering production costs. A common issue in foam-carrying liquid gas wells and wet natural gas pipelines is the large errors observed in the prediction model for liquid accumulation onset, derived using ellipsoidal droplets. Additionally, this model is only applicable to a single surfactant type and concentration. To investigate the effects of different types and concentrations of surfactants on the onset of liquid accumulation. This paper re-establishes the critical foam-carrying flow rate model for spherical cap-shaped foam droplets using Newton's laws of motion, through an analysis of their motion state within the air core. Through the critical foam-carrying flow rate test experiments and foam droplet deformation test experiments to obtain critical foam-carrying flow rate model in the surface tension, foam density, Weber number, drag coefficient and other parameters of the change rule and calculation method. The model's validity was further confirmed using field-measured production data from foam-carrying liquid gas wells, demonstrating accurate validation results. Compared to the previous model, this new model treats foam droplets as spherical cap-shape and introduces a dimensionless scaling factor and foaming capacity to quantify the impact of surfactant types and concentrations on foam droplet surface tension and density. This enhances the model's applicability across different types and concentrations of surfactants with greater accuracy. This offers an efficient, precise, and versatile method for predicting liquid accumulation in foam-carrying liquid gas fields, thereby enhancing the efficiency and safety of gas extraction.

Investigation on coupling deposition and plugging of hydrate and wax in gas–liquid annular flow: Experiments and mechanism

The coupling deposition and plugging caused by hydrate formation and wax precipitation during the development of deep water natural gas resources bring new industrial challenges and theoretical difficulty. We designed a single-pass pipeline with two types to investigate deposition behavior and systematically performed the coupling deposition and plugging of hydrate and wax experiments in gas–liquid annular flow. The experimental results illustrate that the single solid phase of hydrate is covered layer sheet deposition, while the coupling solid phase of hydrate and wax is bulk aggregations arch bridge deposition. Meanwhile, the natural eddy zone in reducing pipeline accelerates coupling solid particles deposition. Our finds provided the first knowledge on the double effect that wax crystals inhibit particles adhesion and gel network increases aggregations arch bridge blockage. For the low water content in emulsion system, the gel network provides gathering place for hydrate particles, and the arch bridge structure formed by aggregations accelerates the pipeline blockage. The plugging time is shortened by up to 72.6% with the wax concentration increase from 0 wt% to 3 wt%. For the high water content in emulsion system, the majority of wax crystals adsorbed on the hydrate particles and reduce particles cohesion force, which increase the plugging time. Combined with the microscopic morphology evolution perspective of hydrate particles coupled wax, the coupling deposition of hydrate and wax in gas–liquid annular flow has four stages: gas–liquid flow, coupling solid phase formation, coupling solid phase deposition and sloughing, and coupling solid phase plugging. This study can provide theoretical support and design basis for flow assurance program of deep water gas fields and low temperature natural gas transportation pipelines.

Amino-functionalized rare earth hexanuclear cluster based MOFs for CO2/CH4 separation

Climate pollution and global warming caused by greenhouse gases have become one of our toughest environmental challenges. CO2 capture and separation from natural gas can effectively reduce CO2 emissions and improve energy efficiency, accordingly, it is a serious challenge faced by industrial separation and scientific research to effectively reduce the carbon dioxide concentration in natural gas pipeline transportation and achieve the acquisition of high-purity methane (>99.5 %). In this study, three stable hexanuclear microporous rare earth cluster-based MOFs (Sm-BDC-NH2, Er-BDC-NH2, Y-BDC-NH2) were successfully synthesized. The selectivity of CO2/CH4 was improved by the introduction of amino groups to achieve better CO2/CH4 separation performance, which was proved by dynamic penetration experiments.

A novel model to predict phase equilibrium state of hydrates from the relationship of gas solubility

The study of hydrate phase equilibrium is crucial for ensuring the safety of natural gas pipeline transportation and the process of hydrate recovery. While scientists typically focus on the chemical potential of hydrates, the role of gas solubility in hydrate phase equilibrium remains unclear, and this study fills this gap. This work investigated the solubility of gas at the equilibrium point of the hydrate phase through model calculations. Additionally, a new model of hydrate phase equilibrium is established based on the relationship between solubility. Firstly, a solubility model based on gas-liquid equilibrium theory showed higher prediction accuracy in comparison to the PR equation and Duan model and was then used to calculate gas solubility under hydrate phase equilibrium conditions. Afterwards, a novel model was developed to predict hydrate equilibrium state based on the relationship between gas solubility and hydrate phase equilibrium temperature, and it was further compared with the Chen–Guo model and CSMGem in terms of prediction accuracy under pure water and brine settings. The results showed: (a) The calculation deviation of the solubility model was 0.7–8.7% in pure water settings and 2.6–11.7% in brine settings; (b) A strong linear correlation between the phase equilibrium temperature of hydrates and gas solubility was also found; (c) This proposed model achieved over 10 times the accuracy of the Chen–Guo model and the CSMGem in predicting the phase equilibrium state of N2 and CO2 hydrates, and 3–10 times higher accuracy than that of the Chen–Guo model and CSMGem in brine. This work suggests that the gas solubility equilibrium theory can provide a more accurate prediction of hydrate states.

A review on hazards and risks to pipeline operation under transporting hydrogen energy and hydrogen-mixed natural gas

As an efficient and clean fuel, hydrogen energy plays an important role in relieving the energy crisis and achieving the orientation of zero carbon emissions. Transportation is the key link in the construction of hydrogen energy infrastructure. For large-scale and long-distance transportation of hydrogen, pipeline transportation has the advantages of high efficiency and cost saving. While using the existing natural gas pipeline to transport hydrogen, it would economize the economic cost, time cost and labor cost. However, the transportation of hydrogen may bring more hazards and risks. Based on the investigation of a large number of literatures, the research advance in hydrogen embrittlement, leakage, combustion and explosion risk of hydrogen and hydrogen-mixed natural gas pipelines was reviewed. The mechanism, research means and evaluation methods of hydrogen embrittlement, as well as the experimental and numerical simulation research results of leakage, combustion and explosion were discussed in detail. The definite and important conclusions include: (1) For buried hydrogen-mixed natural gas transportation pipeline, the leakage rate of hydrogen and methane is the same, the formation of the leakage crater is foreign to the nature of leakage gas. (2) When adding less than 25 volume percentage of hydrogen into the natural gas pipelines, the explosion risk would not be increased. Future research should focus on the risk prediction, quantitative risk assessment, intelligent monitoring, and explosion-suppression technical measures of hydrogen and hydrogen-mixed natural gas transportation pipelines, so as to establish comprehensive and multi-level pipeline safety protection barriers.

Research progress on corrosion and hydrogen embrittlement in hydrogen–natural gas pipeline transportation

Hydrogen, clean, efficient and zero-carbon, is seen as a most promising energy source. The use of existing gas pipelines for hydrogen–natural gas transportation is considered to be an effective way to achieve long-distance, large-scale, efficient, and economical hydrogen transportation. However, the pipelines for hydrogen–natural gas transportation contain lots of impurities (e.g., CH4, high-pressure H2, H2S and CO2) and free water, which will inevitably lead to corrosion and hydrogen embrittlement. This paper presents a systematic review of research and an outlook for corrosion and hydrogen embrittlement in hydrogen–natural gas pipeline transportation. The results show that gas-phase hydrogen charging is suitable for hydrogen–natural gas transportation, but this technique lacks technical standards. By contrast, the liquid-phase hydrogen charging technique is more mature but has large deviation from the engineering reality. In the hydrogen–natural gas transportation pipelines, corrosion and hydrogen embrittlement are synergetic and competitive, but the failure mechanism and change law when corrosion and hydrogen embrittlement coexist remain unclear, which need to be further clarified by experiments. The failure mechanism is believed to be mainly sensitive to three key factors, i.e., the H2S/CO2 partial pressure ratio, the hydrogen blending ratio, and material strength. The increase of the three factors will make the pipeline materials more corrosive and more sensitive to hydrogen embrittlement. The research findings can be used as a reference for research and development of long-distance hydrogen–natural gas transportation technology and will drive the high-quality development of the hydrogen–natural gas blending industry.

Flame evolution and pressure dynamics of methane-hydrogen-air explosion in a horizontal rectangular duct

This work is aimed at exploring flame evolution and pressure dynamics of methane-hydrogen-air explosion experimentally and numerically by changing equivalence ratio and hydrogen content. For the flame evolution, the smooth distortion vanishes at equivalence ratio of Ф = 1.4, the prominent cellular structure and distorted tulip flame start to form with increasing hydrogen content. For the pressure dynamics, as the equivalence ratio increases, both maximum explosion overpressure and maximum pressure rise rate increase and then decrease, and both of them continue to increase with increasing hydrogen content. H + O2 = O + OH is the main elementary reaction with positive effect on the laminar burning velocity. The main elementary reactions with negative effects are H + O2(+M) = HO2(+M) and CH3 + H(+M) = CH4(+M). H radical always dominates on the rich side or the lean, stoichiometric side with high hydrogen content. As the hydrogen content increases, the main oxidation pathways of CH4 undergoes the transfer from CH4 → CH2(S) → CH2 → CO to CH4 → CH2(S) → CH2 → CH → CO → CO2. The research results are helpful to improve combustion efficiency of internal combustion engine and ensure process safety of hydrogen doped natural gas pipeline transportation.

Dynamic scheduling of hydrogen-containing integrated energy systems considering multi-energy transactions

With the continuous development of hydrogen energy production and storage technology, hydrogen energy has gradually become one of the clean energy sources with acceptable cost. The hydrogen decarbonization process of natural gas pipeline transportation and its end energy units such as fuel cells is gradually accelerated. For this reason, considering a variety of energy markets, this paper establishes the operation scheduling model of the integrated energy system (IES) of combined cooling, heating, and power (CCHP) supply with the solid oxide fuel cell (SOFC) as the core which is compared with the traditional gas turbine cogeneration system in the economy and carbon emission reduction and introduces the model predictive control (MPC) algorithm to solve the rolling optimal scheduling scheme. The scheduling results show that the addition of hydrogen conversion units can effectively solve the phenomenon of light abandonment. Under the current energy price, when the proportion of photovoltaic (PV) installed capacity is greater than 0.33, the energy storage potential of hydrogen conversion units can be fully utilized and the economic benefits of SOFC co-production are better than gas turbines. After taking into account the high carbon emission factor of the power grid, there is no big difference in the carbon emission costs of the two cogeneration methods. When the carbon emission factor of the power grid is lower than 0.3 and the hydrogen production efficiency is higher than 75%, the carbon emission reduction benefits of SOFC have obvious advantages.

Development of technology for cascade gas pressure reduction in long gas pipelines of gas distribution stations

The work developed and proposed for implementation an energy-saving technology of pipeline transportation of natural gas along long-distance branch pipelines connecting main gas pipelines and gas distribution stations. This technology consists in a step reduction of operating pressure in the gas pipeline branch with the help of linear reducing stations, with partial heating of gas due to heat exchange between the gas pipeline and the ground. The authors of the article present the results of practical approbation of the cascade gas pressure reduction technology in the operating off-take gas pipeline with the confirmed effect of reducing fuel gas consumption in the gas distribution station preheaters. The optimal parameters of gradual gas pressure reduction using linear reduction points were determined by calculation. Graphical dependencies, which determine the peculiarities of changes in temperature modes of pipeline gas transportation depending on the given pressure drop in linear pressure reduction stations for the conditions of pilot testing of the energy-saving method, have been obtained. A scheme of uniform location of linear pressure reduction stations with definition of the optimal pressure reduction mode is proposed.

Techno assessment on hydrogen injected gas transportation based on integrated system simulation

The key to realizing the remote utilization of hydrogen through hydrogen mixed natural gas transportation lies in the establishment of a complete set of processes from hydrogen blending to pipeline transportation to hydrogen separation. However, the assessment and study of entire process of hydrogen blended gas transportation has rarely been considered. The present study comprehensively investigates the feasibility of natural gas-hydrogen mixture transportation in a high-pressure natural gas transmission system. Specifically, this work proposes a complete set of processes for the pipeline transportation of hydrogen-doped natural gas, including the hydrogen blending process, and the hydrogen separation process. The present study investigates the impacts of various adjustable parameters based on the created simulation object on hydrogen recovery, energy consumption, and turnover rate. The results show a maximum recovery of around 94% for the whole process and a minimum SEC of 1.1 kW h/Nm3 at conventional throughput.

Numerical study of leakage characteristics of hydrogen-blended natural gas in buried pipelines

Pipeline transportation of hydrogen-blended natural gas is susceptible to leakage or rupture accidents caused by pipeline construction, corrosion, and hydrogen embrittlement, posing significant threats to the environment, human safety, and property. This paper improves the model of non-adiabatic pipeline leakage to study the flow characteristics of hydrogen-blended natural gas leakage, and its accuracy is validated using OLGA software and experiment data. The impact of the heat transfer coefficient, initial pressure and hydrogen blending ratio on the leakage flow characteristics is also analyzed. The findings indicate that the initial pressure in the pipe increases linearly at 0.5 MPa and the mass leakage velocity decreases linearly at a rate of nearly 9 kg/s; meanwhile, the temperature drop in the pipe and the overall leakage time increase. An increased hydrogen blending ratio corresponds to lower mass leakage velocity and shorter leakage time. The maximum dangerous distance of pure methane pipeline leakage is greater than that of a pure hydrogen pipeline. Furthermore, changes in the heat transfer coefficient predominantly affect the temperature inside the pipe.

Methods to reduce heat losses when transporting gas through long branch pipelines

The article considers options to reduce heat losses accompanying the process of pipeline transportation of natural gas through long branch pipelines. Computational modeling of the gas cooling process in an extended off-take gas pipeline connecting the main gas pipeline and the gas distribution station has been performed. It is shown that when the length of the gas branch pipeline is long, especially in conditions of reduced flow, the gas temperature at the inlet of the gas distribution station will correspond to the ground temperature. We have developed and substantiated options to reduce the intensity of gas cooling in the off-take gas pipeline, involving an increase in its depth, the use of thermal insulation coatings, as well as the regulation of pressure at the inlet using special technical means. The calculation justification of the technical solution, which involves regulating the pressure at the inlet to the gas pipeline outlet, is performed. The results can be used by gas transportation companies. The implementation of the developed solutions to reduce heat losses will reduce the consumption of energy used for gas heating at gas distribution stations and reduce emissions of combustion products.

Key Technologies of Pure Hydrogen and Hydrogen-Mixed Natural Gas Pipeline Transportation.

Thanks to the advantages of cleanliness, high efficiency, extensive sources, and renewable energy, hydrogen energy has gradually become the focus of energy development in the world's major economies. At present, the natural gas transportation pipeline network is relatively complete, while hydrogen transportation technology faces many challenges, such as the lack of technical specifications, high safety risks, and high investment costs, which are the key factors that hinder the development of hydrogen pipeline transportation. This paper provides a comprehensive overview and summary of the current status and development prospects of pure hydrogen and hydrogen-mixed natural gas pipeline transportation. Analysts believe that basic studies and case studies for hydrogen infrastructure transformation and system optimization have received extensive attention, and related technical studies are mainly focused on pipeline transportation processes, pipe evaluation, and safe operation guarantees. There are still technical challenges in hydrogen-mixed natural gas pipelines in terms of the doping ratio and hydrogen separation and purification. To promote the industrial application of hydrogen energy, it is necessary to develop more efficient, low-cost, and low-energy-consumption hydrogen storage materials.