China, People’s Republic

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation demand-side mitigation or mitigation technologies. Additionally there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo future vision and key actions of the low-carbon development of the world and China’s ISI. First this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency shifting to Scrap/EAF route promoting material efficiency strategy and deploying radical innovation technologies.

To maximize the utilization of renewable energy (RE) as much as possible in cold areas while reducing traditional energy use and carbon dioxide emissions a three-layer configuration optimization and scheduling model considering a multi-park integrated energy system (MPIES) a shared energy storage power station (SESPS) and a hydrogen refueling station (HRS) cooperation based on the Wasserstein generative adversarial networks the simultaneous backward reduction technique and the Quantity-Contour (WGAN-SBR_QC) method is proposed. Firstly the WGAN-SBR_QC method is used to generate typical scenarios of RE output. Secondly a three-layer configuration and schedule optimization model is constructed using MPIES SESPS and HRS. Finally the model’s validity is investigated by selecting a multi-park in Eastern Mongolia. The results show that: (1) the typical scenario of RE output improved the overall robustness of the system. (2) The profits of the MPIES and HRS increased by 1.84% and 52.68% respectively and the SESPS profit increased considerably. (3) The proposed approach increased RE utilization to 99.47% while reducing carbon emissions by 32.67%. Thus this model is a reference for complex energy system configuration and scheduling as well as a means of encouraging RE use.

Hydrogen energy represents a crucial pathway towards achieving carbon neutrality and is a pivotal facet of future strategic emerging industries. The safe and efficient transportation of hydrogen is a key link in the entire chain development of the hydrogen energy industry’s “production storage and transportation”. Mixing hydrogen into natural gas pipelines for transportation is the potential best way to achieve large-scale long-distance safe and efficient hydrogen transportation. Welds are identified as the vulnerable points in natural gas pipelines and compatibility between hydrogen-doped natural gas and existing pipeline welds is a critical technical challenge that affects the global-scale transportation of hydrogen energy. Therefore this article systematically discusses the construction and weld characteristics of hydrogen-doped natural gas pipelines the research status of hydrogen damage mechanism and mechanical property strengthening methods of hydrogen-doped natural gas pipeline welds and points out the future development direction of hydrogen damage mechanism research in hydrogen-doped natural gas pipeline welds. The research results show that: 1 Currently there is a need for comprehensive research on the degradation of mechanical properties in welds made from typical pipe materials on a global scale. It is imperative to systematically elucidate the mechanism of mechanical property degradation due to conventional and hydrogeninduced damage in welds of high-pressure hydrogen-doped natural gas pipelines worldwide. 2 The deterioration of mechanical properties in welds of hydrogen-doped natural gas pipelines is influenced by various components including hydrogen carbon dioxide and nitrogen. It is necessary to reveal the mechanism of mechanical property deterioration of pipeline welds under the joint participation of multiple damage mechanisms under multi-component gas conditions. 3 Establishing a fundamental database of mechanical properties for typical pipeline steel materials under hydrogen-doped natural gas conditions globally is imperative to form a method for strengthening the mechanical properties of typical high-pressure hydrogen-doped natural gas pipeline welds. 4 It is essential to promptly develop relevant standards for hydrogen blending transportation welding technology as well as weld evaluation testing and repair procedures for natural gas pipelines.

Hydrogen energy is regarded as an important way to achieve carbon emission reduction. This paper focuses on the combination of the design of the hydrogen supply chain network and the location of hydrogen refueling stations on the expressway. Based on the cost analysis of the hydrogen supply chain a multi-objective model is developed to determine the optimal scale and location of hydrogen refueling stations on the hydrogen expressway. The proposed model considers the hydrogen demand forecast hydrogen source selection hydrogen production and storage and transportation hydrogen station refueling mode etc. Taking Dalian City China as an example with offshore wind power as a reliable green hydrogen supply to select the location and capacity of hydrogen refueling stations for the hydrogen energy demonstration section of a certain expressway under multiple scenarios. The results of the case show that 4 and 5 stations are optimized on the expressway section respectively and the unit hydrogen cost is $14.3 /kg H2 and $11.8 /kg H2 respectively which are equal to the average hydrogen price in the international range. The optimization results verify the feasibility and effectiveness of the model.

The increasingly severe energy crisis has strengthened the determination todevelop environmentally friendly energy. And hydrogen has emerged as a candi-date for clean energy. Among many hydrogen generation methods biohydrogenstands out due to its environmental sustainability simple operating environ-ment and cost advantages. This review focuses on the rational design of catalystsfor fermentative hydrogen production. The principles of microbial dark fermen-tation and photo-fermentation are elucidated exhaustively. Various strategiesto increase the efficiency of fermentative hydrogen production are summa-rized and some recent representative works from microbial dark fermentationand photo-fermentation are described. Meanwhile perspectives and discussionson the rational design of catalysts for fermentative hydrogen production areprovided.

Water electrolysis is the most promising method for efficient production of high purity hydrogen (and oxygen) while the required power input for the electrolysis process can be provided by renewable sources (e.g. solar or wind). The thus produced hydrogen can be used either directly as a fuel or as a reducing agent in chemical processes such as in Fischer–Tropsch synthesis. Water splitting can be realized both at low temperatures (typically below 100 °C) and at high temperatures (steam water electrolysis at 500– 1000 °C) while different ionic agents can be electrochemically transferred during the electrolysis process (OH− H+ O2− ). Singular requirements apply in each of the electrolysis technologies (alkaline polymer electrolyte membrane and solid oxide electrolysis) for ensuring high electrocatalytic activity and long-term stability. The aim of the present article is to provide a brief overview on the effect of the nature and structure of the catalyst–electrode materials on the electrolyzer’s performance. Past findings and recent progress in the development of efficient anode and cathode materials appropriate for large-scale water electrolysis are presented. The current trends limitations and perspectives for future developments are summarized for the diverse electrolysis technologies of water splitting while the case of CO2/H2O co-electrolysis (for synthesis gas production) is also discussed.

This paper presents a wind-methanol-fuel cell system with hydrogen storage. It can manage various energy flow to provide stable wind power supply produce constant methanol and reduce CO2 emissions. Firstly this study establishes the theoretical basis and formulation algorithms. And then computational experiments are developed with MATLAB/Simulink (R2016a MathWorks Natick MA USA). Real data are used to fit the developed models in the study. From the test results the developed system can generate maximum electricity whilst maintaining a stable production of methanol with the aid of a hybrid energy storage system (HESS). A sophisticated control scheme is also developed to coordinate these actions to achieve satisfactory system performance.

To investigate the leakage characteristics of pure hydrogen and hydrogen-blended natural gas in medium- and low-pressure buried pipelines this study establishes a three-dimensional leakage model based on Computational Fluid Dynamics (CFD). The leakage characteristics in terms of pressure velocity and concentration distribution are obtained and the effects of operational parameters ground hardening degree and leakage parameters on hydrogen diffusion characteristics are analyzed. The results show that the first dangerous time (FDT) for hydrogen leakage is substantially shorter than for natural gas emphasizing the need for timely leak detection and response. Increasing the hydrogen blending ratio accelerates the diffusion process and decreases the FDT posing greater risks for pipeline safety. The influence of soil hardening on gas diffusion is also examined revealing that harder soils can restrict gas dispersion thereby increasing localized concentrations. Additionally the relationship between gas leakage time and distance is determined aiding in the optimal placement of gas sensors and prediction of leakage timing. To ensure the safe operation of hydrogen-blended natural gas pipelines practical recommendations include optimizing pipeline operating conditions improving leak detection systems increasing pipeline burial depth and selecting materials with higher resistance to hydrogen embrittlement. These measures can mitigate risks associated with hydrogen leakage and enhance the overall safety of the pipeline infrastructure.

As an important piece of equipment for hydrogen energy application the hydrogen internal combustion engine is helpful for the realization of zero carbon emissions where the aluminum connecting rod is one of the key core components. A semi-solid forging forming process for the 7075 aluminum alloy connecting rod is proposed in this work. The influence of process parameters such as the forging ratio sustaining temperature and duration time on the microstructures of the semi-solid blank is experimentally investigated. The macroscopic morphology metallographic structure and physical properties of the connecting-rod parts are analyzed. Reasonable process parameters for preparing the semi-solid blank are obtained from the experimental results. Under the reasonable parameters the average grain size is 41.48~42.57 µm and the average shape factor is 0.80~0.81. The yield strength and tensile strength improvement ratio of the connecting rod produced by the proposed process are 47.07% and 20.89% respectively.

The depletion of fossil fuel reserves has resulted from their application in the industrial and energy sectors. As a result substantial efforts have been dedicated to fostering the shift from fossil fuels to renewable energy sources via technological advancements in industrial processes. Microalgae can be used to produce biofuels such as biodiesel hydrogen and bioethanol. Microalgae are particularly suitable for hydrogen production due to their rapid growth rate ability to thrive in diverse habitats ability to resolve conflicts between fuel and food pro duction and capacity to capture and utilize atmospheric carbon dioxide. Therefore microalgae-based bio hydrogen production has attracted significant attention as a clean and sustainable fuel to achieve carbon neutrality and sustainability in nature. To this end the review paper emphasizes recent information related to microalgae-based biohydrogen production mechanisms of sustainable hydrogen production factors affecting biohydrogen production by microalgae bioreactor design and hydrogen production advanced strategies to improve efficiency of biohydrogen production by microalgae along with bottlenecks and perspectives to over come the challenges. This review aims to collate advances and new knowledge emerged in recent years for microalgae-based biohydrogen production and promote the adoption of biohydrogen as an alternative to con ventional hydrocarbon biofuels thereby expediting the carbon neutrality target that is most advantageous to the environment.

Hydrogen–gasoline hybrid refueling stations can minimize construction and management costs and save land resources and are gradually becoming one of the primary modes for hydrogen refueling stations. However catastrophic consequences may be caused as both hydrogen and gasoline are flammable and explosive. It is crucial to perform an effective risk assessment to prevent fire and explosion accidents at hybrid refueling stations. This study conducted a risk assessment of the refueling area of a hydrogen–gasoline hybrid refueling station based on the improved Accident Risk Assessment Method for Industrial Systems (ARAMIS). An improved probabilistic failure model was used to make ARAMIS more applicable to hydrogen infrastructure. Additionally the accident consequences i.e. jet fires and explosions were simulated using Computational Fluid Dynamics (CFD) methods replacing the traditional empirical model. The results showed that the risk levels at the station house and the road near the refueling area were 5.80 × 10−5 and 3.37 × 10−4 respectively and both were within the acceptable range. Furthermore the hydrogen dispenser leaked and caused a jet fire and the flame ignited the exposed gasoline causing a secondary accident considered the most hazardous accident scenario. A case study was conducted to demonstrate the practicability of the methodology. This method is believed to provide trustworthy decisions for establishing safe distances from dispensers and optimizing the arrangement of the refueling area.

This paper proposes an energy management strategy for a fuel cell (FC) hybrid power system based on dynamic programming and state machine strategy which takes into account the durability of the FC and the hydrogen consumption of the system. The strategy first uses the principle of dynamic programming to solve the optimal power distribution between the FC and supercapacitor (SC) and then uses the optimization results of dynamic programming to update the threshold values in each state of the finite state machine to realize real-time management of the output power of the FC and SC. An FC/SC hybrid tramway simulation platform is established based on RTLAB real-time simulator. The compared results verify that the proposed EMS can improve the durability of the FC increase its working time in the high-efficiency range effectively reduce the hydrogen consumption and keep the state of charge in an ideal range.

The most challenging aspect of developing a green hydrogen economy is long-distance oceanic transportation. Hydrogen liquefaction is a transportation alternative. However the cost and energy consumption for liquefaction is currently prohibitively high creating a major barrier to hydrogen supply chains. This paper proposes using solid nitrogen or oxygen as a medium for recycling cold energy across the hydrogen liquefaction supply chain. When a liquid hydrogen (LH2) carrier reaches its destination the regasification process of the hydrogen produces solid nitrogen or oxygen. The solid nitrogen or oxygen is then transported in the LH2 carrier back to the hydrogen liquefaction facility and used to reduce the energy consumption cooling gaseous hydrogen. As a result the energy required to liquefy hydrogen can be reduced by 25.4% using N2 and 27.3% using O2. Solid air hydrogen liquefaction (SAHL) can be the missing link for implementing a global hydrogen economy.

This study investigates the techno-economic feasibility of an off-grid integrated solar/wind/hydrokinetic plant to co-generate electricity and hydrogen for a remote micro-community. In addition to the techno-economic viability assessment of the proposed system via HOMER (hybrid optimization of multiple energy resources) a sensitivity analysis is conducted to ascertain the impact of ±10% fluctuations in wind speed solar radiation temperature and water velocity on annual electric production unmet electricity load LCOE (levelized cost of electricity) and NPC (net present cost). For this a far-off village with 15 households is selected as the case study. The results reveal that the NPC LCOE and LCOH (levelized cost of hydrogen) of the system are equal to $333074 0.1155 $/kWh and 4.59 $/kg respectively. Technical analysis indicates that the PV system with the rated capacity of 40 kW accounts for 43.7% of total electricity generation. This portion for the wind turbine and the hydrokinetic turbine with nominal capacities of 10 kW and 20 kW equates to 23.6% and 32.6% respectively. Finally the results of sensitivity assessment show that among the four variables only a +10% fluctuation in water velocity causes a 20% decline in NPC and LCOE.

Harnessing surplus wind and solar energy for water electrolysis boosts the efficiency of renewable energy utilization and supports the development of a low-carbon energy framework. However the intermittent and unpredictable nature of wind and solar power generation poses significant challenges to the dynamic stability and hydrogen production efficiency of electrolyzers. This study introduces a multi-state rotational control strategy for a hybrid electrolyzer system designed to produce hydrogen. Through a detailed examination of the interplay between electrolyzer power and efficiency—along with operational factors such as load range and startup/shutdown times—six distinct operational states are categorized under three modes. Taking into account the differing dynamic response characteristics of proton exchange membrane electrolyzers (PEMEL) and alkaline electrolyzers (AEL) a power-matching mechanism is developed to optimize the performance of these two electrolyzer types under varied and complex conditions. This mechanism facilitates coordinated scheduling and seamless transitions between operational states within the hybrid system. Simulation results demonstrate that compared to the traditional sequential startup and shutdown approach the proposed strategy increases hydrogen production by 10.73% for the same input power. Moreover it reduces the standard deviation and coefficient of variation in operating duration under rated conditions by 27.71 min and 47.04 respectively thereby enhancing both hydrogen production efficiency and the dynamic operational stability of the electrolyzer cluster.

To mitigate the risk of hydrogen leakage in ship fuel systems powered by internal combustion engines a Bayesian network model was developed to evaluate the risk of hydrogen fuel leakage. In conjunction with the Bow-tie model fuzzy set theory and the Noisy-OR Gate model an in-depth analysis was also conducted to examine both the causal factors and potential consequences of such incidents. The Bayesian network model estimates the likelihood of hydrogen leakage at approximately 4.73 × 10−4 and identifies key risk factors contributing to such events including improper maintenance procedures inadequate operational protocols and insufficient operator training. The Bowtie model is employed to visualize the causal relationships between risk factors and their potential consequences providing a clear structure for understanding the events leading to hydrogen leakage. Fuzzy set theory is used to address the uncertainties in expert judgments regarding system parameters enhancing the robustness of the risk analysis. To mitigate the subjectivity inherent in root node probabilities and conditional probability tables the NoisyOR Gate model is introduced simplifying the determination of conditional probabilities and improving the accuracy of the evaluation. The probabilities of flash or pool fires jet fires and vapor cloud explosions following a leakage are calculated as 4.84 × 10−5 5.15 × 10−5 and 4.89 × 10−7 respectively. These findings highlight the importance of strengthening operator training and enforcing stringent maintenance protocols to mitigate the risks of hydrogen leakage. The model provides a valuable framework for safety evaluation and leakage risk management in hydrogen-powered ship fuel systems.

The burgeoning adoption of photovoltaic and wind energy has limitations of volatility and intermittency which hinder their application. Electro-hydrogen coupling energy storage systems emerge as a promising solution to address this issue. This technology combines renewable energy power generation with hydrogen production through water electrolysis and hydrogen fuel cell power generation effectively enabling the consumption and peak load management of renewable energy sources. This paper presents a power system with a 10 kW photovoltaic system and lithium battery energy storage system designed for hydrogen-electric coupled energy storage validated through the physical experiments. The results demonstrate the system's effectiveness in mitigating the impact of randomness and volatility in photovoltaic power generation. Moreover the energy management system can adjust bus power based on load demand. Testing the system in the absence of photovoltaic power generation reveals its capability to supply energy to the load for three hours with a minimum operating load power of 3 kW even under weather conditions unsuitable for photovoltaic power generation. These findings showed the potential of electro-hydrogen coupling energy storage systems in addressing the challenges associated with renewable energy integration paving the way for a reliable and sustainable energy supply.

Under the guidance of energy-saving and emission reduction goals a lowcarbon economic operation method for integrated energy systems (IES) has been proposed. This strategy aims to enhance energy utilization efficiency bolster equipment operational flexibility and significantly cut down on carbon emissions from the IES. Firstly a thorough exploration of the two-stage operational framework of Power-to-Gas (P2G) technology is conducted. Electrolyzers methane reactors and hydrogen fuel cells (HFCs) are introduced as replacements for traditional P2G equipment with the objective of harnessing the multiple benefits of hydrogen energy. Secondly a cogeneration and HFC operational strategy with adjustable heat-to-electricity ratio is introduced to further enhance the IES’s low-carbon and economic performance. Finally a step-by-step carbon trading mechanism is introduced to effectively steer the IES towards carbon emission control.

Driven by the current round of technological revolution and industrial transformation and based on a consensus among countries around the world the world’s energy landscape is undergoing profound adjustments to promote a transition to clean low-carbon energy in order to cope with global climate change. As a clean and carbon-free secondary energy source hydrogen energy is an important component of the energy strategy in various countries. Fuel cell technology is also of great importance in directing the current global energy technology revolution. China has clarified its sustainable energy goals: to peak its carbon dioxide emissions [1] and achieve carbon neutrality [2]. With thorough development of technology and the industry hydrogen energy will play a significant role in achieving these goals.

The coupling of renewable energy sources with electrolyzers under standalone conditions significantly enhances the operational efficiency and improves the costeffectiveness of electrolyzers as a technologically viable and sustainable solution for green hydrogen production. To address the configuration optimization challenge in hybrid electrolyzer systems integrating alkaline water electrolysis (AWE) and proton exchange membrane electrolysis (PEME) this study proposes an innovative methodology leveraging the morphological analysis of Pareto frontiers to determine the optimal solutions under multi-objective functions including the hydrogen production cost and efficiency. Then the complementary advantages of AWE and PEME are explored. The proposed methodology demonstrated significant performance improvements compared with the single-objective optimization function. When contrasted with the economic optimization function the hybrid system achieved a 1.00% reduction in hydrogen production costs while enhancing the utilization efficiency by 21.71%. Conversely relative to the efficiency-focused optimization function the proposed method maintained a marginal 5.22% reduction in utilization efficiency while achieving a 6.46% improvement in economic performance. These comparative results empirically validate that the proposed hybrid electrolyzer configuration through the implementation of the novel optimization framework successfully establishes an optimal balance between the economy and efficiency of hydrogen production. Additionally a discussion on the key factors affecting the rated power and mixing ratio of the hybrid electrolyzer in this research topic is provided.

Hydrogen specifications for different scenarios are various. Based on national standards for China a comparison of hydrogen specification standards is discussed in this paper including specification standards for industrial hydrogen pure hydrogen high pure hydrogen ultrapure hydrogen hydrogen for electronic industry and hydrogen for PEM FCVs. Hydrogen purity for electronic industry is greater than that for industrial hydrogen pure hydrogen and hydrogen for PEM FCVs. Specifications of general contaminants in hydrogen for electronic industry including H2O O2 N2 CO CO2 and total hydrocarbons are stricter than that in hydrogen for PEM FCVs. Hydrogen purity for PEM FCVs is less than that for electronic industry and pure hydrogen. However contaminants in hydrogen for PEM FCVs are strict. Contaminants in hydrogen for PEM FCVs should include not only H2O O2 N2 CO CO2 Ar and total hydrocarbons but also helium total sulfur compounds formaldehyde formic acid ammonia halogenated compounds and particulates.

To mitigate challenges arising from renewable energy volatility and multi-energy load uncertainty this paper introduces a dynamic hydrogen blending (DHB) strategy for an integrated energy system. The strategy is categorized into Continuous Hydrogen Blending (CHB) and Time-phased Hydrogen Blending (THB) based on the temporal variations in the hydrogen blending ratio. To evaluate the regulatory effect of DHB on uncertainty a datadriven distributionally robust optimization method is employed in the day-ahead stage to manage system uncertainties. Subsequently a hierarchical model predictive control framework is designed for the intraday stage to track the day-ahead robust scheduling outcomes. Experimental results indicate that the optimized CHB ratio exhibits step characteristics closely resembling the THB configuration. In terms of cost-effectiveness CHB reduces the day-ahead scheduling cost by 0.87% compared to traditional fixed hydrogen blending schemes. THB effectively simplifies model complexity while maintaining a scheduling performance comparable to CHB. Regarding tracking performance intraday dynamic hydrogen blending further reduces upper- and lower-layer tracking errors by 4.25% and 2.37% respectively. Furthermore THB demonstrates its advantage in short-term energy regulation effectively reducing tracking errors propagated from the upper layer MPC to the lower layer resulting in a 2.43% reduction in the lower-layer model’s tracking errors.

The existence of a large number of abandoned salt caverns in China has posed a great threat to geological safety and environmental protection and it also wasted enormous underground space resources. To address such problems comprehensive utilization of these salt caverns has been proposed both currently and in the future mainly consisting of energy storage and waste disposal. Regarding energy storage in abandoned salt caverns the storage media such as gas oil compressed air and hydrogen have been introduced respectively in terms of the current development and future implementation with siteselection criteria demonstrated in detail. The recommended burial depth of abandoned salt caverns for gas storage is 1000–1500 m while it should be less than 1000 m for oil storage. Salt cavern compressed air storage has more advantages in construction and energy storage economics. Salt cavern hydrogen storage imposes stricter requirements on surrounding rock tightness and its location should be near the hydrogen production facilities. The technical idea of storing ammonia in abandoned salt caverns (indirect hydrogen storage) has been proposed to enhance the energy storage density. For the disposal of wastes including low-level nuclear waste and industrial waste the applicable conditions technical difficulties and research prospects in this field have been reviewed. The disposal of nuclear waste in salt caverns is not currently recommended due to the complex damage mechanism of layered salt rock and the specific locations of salt mines in China. Industrial waste disposal is relatively mature internationally but in China policy and technical research require strengthening to promote its application. Furthermore considering the recovery of salt mines and the development of salt industries the cooperation between energy storage regions and salt mining regions has been discussed. The economic and environmental benefits of utilizing abandoned salt caverns have been demonstrated. This study provides a solution to handle the abandoned salt caverns in China and globally.

Hydrogen energy as a medium for long-term energy storage needs to ensure the continuous and stable operation of the electrolyzer during the production of green hydrogen using wind energy. In this paper based on the overall model of a wind power hydrogen production system an integrated control strategy aimed at improving the quality of wind power generation smoothing the hydrogen production process and enhancing the stability of the system is proposed. The strategy combines key measures such as the maximum power point tracking control of the wind turbine and the adaptive coordinated control of the electrochemical energy storage system which can not only efficiently utilize the wind resources but also effectively ensure the stability of the bus voltage and the smoothness of the hydrogen production process. The simulation results show that the electrolyzer can operate at full power to produce hydrogen while the energy storage device is charging when wind energy is sufficient; the electrolyzer continuously produces hydrogen according to the wind energy when the wind speed is normal; and the energy storage device will take on the task of maintaining the operation of the electrolyzer when the wind speed is insufficient to ensure the stability and reliability of the system.

MgH2 shows significant potential for a solid-state hydrogen storage medium due to the advantages of high hydrogen capacity excellent reversibility and low cost. However its large-scale application still requires overcoming significant thermodynamic and kinetic hurdles. Catalyst design and optimization enhancements are crucial for the hydrogen storage properties of MgH2 wherein single-atom catalysts characterized by their small size and high proportion of unsaturated coordination sites have recently demonstrated a significant advance and considerable promise in this regard. This review presents recent progress on state-of-the-art single-atom catalysts for enhancing MgH2 hydrogen storage examining both supported and unsupported catalyst types i.e. transition metal @ N-modified carbon materials and transition metal @ transition metal compounds and metallene-derived compounds and single-atom alloys respectively. We systematically discussed the single-atom catalysts in MgH2 hydrogen storage systems focusing on synthesis strategies characterization techniques catalytic mechanisms as well as existing challenges and future perspectives. We aimed to provide a comprehensive and cohesive understanding for researchers in the field and promote the development of single-atom catalysts and their significant optimization of the hydrogen storage performance of MgH2.