Transmission, Distribution & Storage

Positive Energy Districts can be defined as connected urban areas or energy-efficient and flexible buildings which emit zero greenhouse gases and manage surpluses of renewable energy production. Energy storage is crucial for providing flexibility and supporting renewable energy integration into the energy system. It can balance centralized and distributed energy generation while contributing to energy security. Energy storage can respond to supplement demand provide flexible generation and complement grid development. Photovoltaics and wind turbines together with solar thermal systems and biomass are widely used to generate electricity and heating respectively coupled with energy system storage facilities for electricity (i.e. batteries) or heat storage using latent or sensible heat. Energy storage technologies are crucial in modern grids and able to avoid peak charges by ensuring the reliability and efficiency of energy supply while supporting a growing transition to nondepletable power sources. This work aims to broaden the scientific and practical understanding of energy storage in urban areas in order to explore the flexibility potential in adopting feasible solutions at district scale where exploiting the space and resource-saving systems. The main objective is to present and critically discuss the available options for energy storage that can be used in urban areas to collect and distribute stored energy. The concerns regarding the installation and use of Energy Storage Systems are analyzed by referring to regulations and technical and environmental requirements as part of broader distribution systems or as separate parts. Electricity heat energy and hydrogen are the most favorable types of storage. However most of them need new regulations technological improvement and dissemination of knowledge to all people with the aim of better understanding the benefits provided.

Hydrogen is one of the main energy carriers playing a prominent role in the future decarbonization of the economy. However several aspects regarding the transport and storage of this gas are challenging. The intermediary conversion of hydrogen into high-density energy molecules may be a crucial step until technological conditions are ready to attain a significant reduction in fossil fuel use in transport and the industrial sector. The process of transforming hydrogen into methane by anaerobic digestion is reviewed showing that this technology is a feasible option for facilitating hydrogen storage and transport. The manuscript focuses on the role of anaerobic digestion as a technology driver capable of fast adaptation to current energy needs. The use of thermophilic systems and reactors capable of increasing the contact between the H2 -fuel and liquid phase demonstrated outstanding capabilities attaining higher conversion rates and increasing methane productivity. Pressure is a relevant factor of the process allowing for better hydrogen solubility and setting the basis for considering feasible underground hydrogen storage concomitant with biological methanation. This feature may allow the integration of sequestered carbon dioxide as a relevant substrate.

To meet the global climate goals agreed upon regarding the Paris Agreement governments and institutions around the world are investigating various technologies to reduce carbon emissions and achieve a net-negative energy system. To this end integrated solutions that incorporate carbon utilization processes as well as promote the transition of the fossil fuel-based energy system to carbon-free systems such as the hydrogen economy are required. One of the possible pathways is to utilize CO2 as the base chemical for producing a liquid organic hydrogen carrier (LOHC) using CO2 as a mediating chemical for delivering H2 to the site of usage since gaseous and liquid H2 retain transportation and storage problems. Formic acid is a probable candidate considering its high volumetric H2 capacity and low toxicity. While previous studies have shown that formic acid is less competitive as an LOHC candidate compared to other chemicals such as methanol or toluene the results were based on out-of-date process schemes. Recently advances have been made in the formic acid production and dehydrogenation processes and an analysis regarding the recent process configurations could deem formic acid as a feasible option for LOHC. In this study the potential for using formic acid as an LOHC is evaluated with respect to the state-of-the-art formic acid production schemes including the use of heterogeneous catalysts during thermocatalytic and electrochemical formic acid production from CO2 . Assuming a hydrogen distribution system using formic acid as the LOHC each of the production transportation dehydrogenation and CO2 recycle sections are separately modeled and evaluated by means of techno-economic analysis (TEA) and life cycle assessment (LCA). Realistic scenarios for hydrogen distribution are established considering the different transportation and CO2 recovery options; then the separate scenarios are compared to the results of a liquefied hydrogen distribution scenario. TEA results showed that while the LOHC system incorporating the thermocatalytic CO2 hydrogenation to formic acid is more expensive than liquefied H2 distribution the electrochemical CO2 reduction to formic acid system reduces the H2 distribution cost by 12%. Breakdown of the cost compositions revealed that reduction of steam usage for thermocatalytic processes in the future can make the LOHC system based on thermocatalytic CO2 hydrogenation to formic acid to be competitive with liquefied H2 distribution if the production cost could be reduced by 23% and 32% according to the dehydrogenation mode selected. Using formic acid as a LOHC was shown to be less competitive compared to liquefied H2 delivery in terms of LCA but producing formic acid via electrochemical CO2 reduction was shown to retain the lowest global warming potential among the considered options.

The transition to a decarbonized gas network requires the adaptation of existing infrastructure to accommodate hydrogen and hydrogen-enriched natural gas. This study presents the development of calibration facilities at NEL VSL and DNV for evaluating the performance of flow meters under hydrogen conditions. Nine flow meters were tested covering applications from household consumption to distribution networks. Results demonstrated that rotary displacement meters and diaphragm meters are typically suitable for hydrogen and hydrogenenriched natural gas domestic and commercial consumers use. Tests results for an orifice meter confirmed that a discharge coefficient calibrated with nitrogen can be reliably used for hydrogen by matching Reynolds numbers. Thermal mass flow meters when not configured for the specific test gas exhibited significant errors emphasizing the necessity of gas-specific calibration and configuration. Turbine meters showed predictable error trends influenced by Reynolds number and bearing friction with natural gas calibration providing reliable hydrogen and hydrogen-enriched natural gas performance in the Reynolds domain. It was confirmed that ultrasonic meter performance varies by manufacturers with some meter models requiring a correction for gas composition bias when used in hydrogen enriched natural gas applications. These findings provide critical experimental data to guide future hydrogen metering standards and infrastructure adaptations supporting the European Union’s goal of integrating hydrogen into the gas network.

Green hydrogen can be efficiently produced in regions rich in renewable sources far from the European largeproduction sites and delivered to the continent for utilization in the industrial and mobility sectors. In this work the transportation of hydrogen from North Africa to North Italy in its liquefied form is considered. A technoeconomic assessment is performed on its value chain which includes liquefaction storage maritime transport distribution regasification and compression. The calculated transport cost for the industrial application (delivery to a hydrogen valley) ranges from 6.14 to 9.16 €/kg while for the mobility application (delivery to refueling stations) the range is 10.96–17.71 €/kg. In the latter case the most cost-effective configuration involves the distribution of liquefied hydrogen and regasification at the refueling stations. The liquefaction process is the cost driver of the value chain in all the investigated cases suggesting the importance of its optimization to minimize the overall transport cost.

The intermittent production of the renewable energy imposes the necessity to temporarily store it. Large amounts of exceeding electricity can be stored in geological strata in the form of hydrogen. The conversion of hydrogen to electricity and vice versa can be performed in electrolyzers and fuel elements by chemical methods. The nowadays technical solution accepted by the European industry consists of injecting small concentrations of hydrogen in the existing storages of natural gas. The progressive development of this technology will finally lead to the creation of underground storages of pure hydrogen. Due to the low viscosity and low density of hydrogen it is expected that the problem of an unstable displacement including viscous fingering and gravity overriding will be more pronounced. Additionally the injection of hydrogen in geological strata could encounter chemical reactivity induced by various species of microorganisms that consume hydrogen for their metabolism. One of the products of such reactions is methane produced from Sabatier reaction between H2 and CO2. Other hydrogenotrophic reactions could be caused by acetogenic archaea sulfate-reducing bacteria and iron-reducing bacteria. In the present paper a mathematical model is presented which is capable to reflect the coupled hydrodynamic and bio-chemical processes in UHS. The model has been numerically implemented by using the open source code DuMuX developed by the University of Stuttgart. The obtained bio-chemical version of DuMuX was used to model the evolution of a hypothetical underground storage of hydrogen. We have revealed that the behavior of an underground hydrogen storage is different than that of a natural gas storage. Both the hydrodynamic and the bio-chemical effects contribute to the different characteristics.

Installations of decentralised renewable energy systems (RES) are becoming increasing popular as governments introduce ambitious energy policies to curb emissions and slow surging energy costs. This work presents a novel model for optimal sizing for a decentralised renewable generation and hybrid storage system to create a renewable energy community (REC) developed in Python. The model implements photovoltaic (PV) solar and wind turbines combined with a hybrid battery and regenerative hydrogen fuel cell (RHFC). The electrical service demand was derived using real usage data from a rural island case study location. Cost remuneration was managed with an REC virtual trading layer ensuring fair distribution among actors in accordance with the European RED(III) policy. A multi-objective genetic algorithm (GA) stochastically determines the system capacities such that the inherent trade-off relationship between project cost and decarbonisation can be observed. The optimal design resulted in a levelized cost of electricity (LCOE) of 0.15 EUR/kWh reducing costs by over 50% compared with typical EU grid power with a project internal rate of return (IRR) of 10.8% simple return of 9.6%/year and return on investment (ROI) of 9 years. The emissions output from grid-only use was reduced by 72% to 69 gCO2 e/kWh. Further research of lifetime economics and additional revenue streams in combination with this work could provide a useful tool for users to quickly design and prototype future decentralised REC systems.

As Sweden takes its first steps towards a hydrogen-based economy a strategic approach to infrastructure development for both storage and delivery becomes necessary. Although compressed hydrogen is currently the state-of-the-art its low volumetric density and associated high capital costs pose challenges to widespread societal deployment of hydrogen. In order to avoid technological lock-in alternatives storage technologies including chemical hydrides e.g. methanol ammonia methane and LOHC must also be explored. These alternatives offer higher hydrogen densities safer handling and compatibility with existing infrastructure. However each hydride has unique chemical and physical properties requires distinct feedstock and conversion processes and interacts with the energy system in different ways all of which influences their suitability for various applications. Therefore a comprehensive evaluation of these alternative hydrogen storage technologies as carried out in this article is vital to allow for informed investment decisions and pave the way towards a successful and sustainable hydrogen economy.

The seal and weight of the Type IV hydrogen storage vessel are the key problems restricting the safety and driving range of fuel cell vehicles. The boss as a metal medium connecting the inner liner of the Type IV hydrogen storage vessel with the external pipeline affects the sealing performance of the Type IV hydrogen storage vessel and there is no academic research on the weight of the boss. Therefore according to the force characteristics of the boss this paper divides the upper and lower areas (valve column and plate). The valve column with seal optimization and light weight is manufactured with a 3D printing additive while the plate bearing and transferring the internal pressure load is manufactured by forging. Firstly a two-dimensional axisymmetric simulation model of the sealing ring was established and the effects of different compression rates on its seal performance were analyzed. Then the size and position of the sealing groove were sampled simulated and optimized based on the Latin Hypercube method and the reliability of the optimal seal structure was verified by experiments. Finally the Solid Isotropic Material with Penalization (SIMP) topology method was used to optimize the weight of the boss with optimal sealing structure and the reconstructed model was checked and analyzed. The results show that the weight of the optimized boss is reduced by 9.6%.

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.

Seasonal storage of natural gas (NG) which primarily consists of methane (CH4) has been practiced for more than a hundred years at underground gas storage (UGS) facilities that use depleted hydrocarbon reservoirs saline aquifers and salt caverns. To support a transition to a hydrogen (H2) economy similar facilities are envisioned for long-duration underground H2 storage (UHS) of either H2 or H2/CH4 mixtures. Experience with UGS can be used to guide the deployment of UHS so we identify and quantify factors (formation/fluid properties and engineering choices) that influence reservoir behavior (e.g. viscous fingering and gravity override) the required number of injection/withdrawal wells and required storage volume contrasting the differences between the storage of CH4 H2 and H2/CH4 mixtures. The most important engineering choices are found to be the H2 fraction in H2/CH4 mixtures storage depth and injection rate. Storage at greater depths (higher pressure) but with relatively lower temperature is more favorable because it maximizes volumetric energy-storage density while minimizing viscous fingering and gravity override due to buoyancy. To store an equivalent amount of energy storing H2/CH4 mixtures in UHS facilities will require more wells and greater reservoir volume than corresponding UGS facilities. We use our findings to make recommendations about further research needed to guide deployment of UHS in porous reservoirs.

This comprehensive review explores the transformative role of nanomaterials in advancing the frontier of hydrogen energy specifcally in the realms of storage production and transport. Focusing on key nanomaterials like metallic nanoparticles metal–organic frameworks carbon nanotubes and graphene the article delves into their unique properties. It scrutinizes the application of nanomaterials in hydrogen storage elucidating both challenges and advantages. The review meticulously evaluates diverse strategies employed to overcome limitations in traditional storage methods and highlights recent breakthroughs in nanomaterial-centric hydrogen storage. Additionally the article investigates the utilization of nanomaterials to enhance hydrogen production emphasizing their role as efcient nanocatalysts in boosting hydrogen fuel cell efciency. It provides a comprehensive overview of various nanocatalysts and their potential applications in fuel cells. The exploration extends to the realm of hydrogen transport and delivery specifcally in storage tanks and pipelines ofering insights into the nanomaterials investigated for this purpose and recent advancements in the feld. In conclusion the review underscores the immense potential of nanomaterials in propelling the hydrogen energy frontier. It emphasizes the imperative for continued research aimed at optimizing the properties and performance of existing nanomaterials while advocating for the development of novel nanomaterials with superior attributes for hydrogen storage production and transport. This article serves as a roadmap shedding light on the pivotal role nanomaterials can play in advancing the development of clean and sustainable hydrogen energy technologies.

The on-board hydrogen storage of mobile applications is a key area of global industrial transformation to hydrogen technology. The research work provides an overview about the principle of hydrogen fuel cell vehicles with a focus on the widespread on-board hydrogen storage technologies. In this work type IV composite pressure vessels in particular are reviewed. The key challenges of polymeric liners are deeply investigated and liner collapse was identified as a critical failure of type IV vessels. Different factors of liner collapse were categorized and relevant material properties - such as permeability physical characteristics and surface properties - were explained in more detail to lay the foundation for further research on high barrier durable polymeric liner materials.

As global energy shifts toward sustainable solutions switching to sustainable energy particularly those involving energy storage from hydrogen relies on effective storage technologies. This is necessary for harnessing the potential of hydrogen as a clean energy carrier. This review discussed the latest advancements in materials designed to improve hydrogen storage efficiency safety and scalability. The articles reported different storage materials such as metal hydrides chemical hydrides advanced adsorbents and their challenges and prospects. Developing innovations like nanostructured and hybrid materials are explained showing how these cutting-edge approaches improve hydrogen kinetics. However despite the advancements challenges like feasibility and sustainability remain. Hence this study discusses these barriers through life cycle assessments and recycling. Moreover the study offers an understanding of the applications of these materials illustrating their prospects to simplify a hydrogen economy. Through examining current research and identifying important trends the article aims to illuminate the way forward for materials science in hydrogen storage applications. The findings highlight the importance of material development and emphasise the collaborative efforts researchers require to realise the potential of hydrogen as a keystone of sustainable energy systems.

This work included preparing and characterizing new platinum complexes with the ligand 345 -trimethoxybenzoic acid (TMB). The reactions were carried out using a n autoclave in microwave within 3 minutes only in an alkali medium of triethylamine where two moles of TMB reacted with one mole of platinum ion and two moles of PPh 3 or with one mole of diphosphines (Bis(diphenylphosphino)x; x=methane (dppm) ethane (dppe) propane (dppp) ferrocene (dppf)). The prepared complexes were characterized by measuring melting points and by the techniques of (C.H.N) molar electrical conductivity FT -IR and 1 H -NMR. The characterization results demonstrated that the TMB ligand behaves as a bidentate ligand through the oxygen atom of the carboxylic groups and its geometric shape is a square planar around the platinum ion. The complex formed with high yield ([Pt(TMB) 2(dppf)]) was used in hydrogen storage application. The storage isotherm showed that the complex has a high storage capacity of about 4.2 wt% at 61 bar under low temperature (77 K). The study showed that the thermodynamic functions were -0.67KJ/mol and -3.6 J/mol H 2 for enthalpy and entropy indicating the occurrence of physical hydrogen storage.

The increasing global energy demand and the transition toward sustainable energy systems have highlighted the importance of energy storage technologies by ensuring efficiency reliability and decarbonization. This study reviews chemical and thermal energy storage technologies focusing on how they integrate with renewable energy sources industrial applications and emerging challenges. Chemical Energy Storage systems including hydrogen storage and power-to-fuel strategies enable long-term energy retention and efficient use while thermal energy storage technologies facilitate waste heat recovery and grid stability. Key contributions to this work are the exploration of emerging technologies challenges in large-scale implementation and the role of artificial intelligence in optimizing Energy Storage Systems through predictive analytics real-time monitoring and advanced control strategies. This study also addresses regulatory and economic barriers that hinder widespread adoption emphasizing the need for policy incentives and interdisciplinary collaboration. The findings suggest that energy storage will be a fundamental pillar of the sustainable energy transition. Future research should focus on improving material stability enhancing operational efficiency and integrating intelligent management systems to maximize the benefits of these technologies for a resilient and low-carbon energy infrastructure.

Hydrogen is widely recognized as a key enabler of the clean energy transition but the lack of safe efficient and scalable storage technologies continues to hinder its broad deployment. Conventional hydrogen storage approaches such as compressed hydrogen storage cryo-compressed hydrogen storage and liquid hydrogen storage face limitations including high energy consumption elevated cost weight and safety concerns. In contrast solid-state hydrogen storage using carbon-based adsorbents has gained growing attention due to their chemical tunability low cost and potential for modular integration into energy systems. This review provides a comprehensive evaluation of hydrogen storage using carbon-based materials covering fundamental adsorption mechanisms classical materials emerging architectures and recent advances in computationally AI-guided material design. We first discuss the physicochemical principles driving hydrogen physisorption chemisorption Kubas interaction and spillover effects on carbon surfaces. Classical adsorbents such as activated carbon carbon nanotubes graphene carbon dots and biochar are evaluated in terms of pore structure dopant effects and uptake capacity. The review then highlights recent progress in advanced carbon architectures such as MXenes three-dimensional architectures and 3D-printed carbon platforms with emphasis on their gravimetric and volumetric performance under practical conditions. Importantly this review introduces a forward-looking perspective on the application of artificial intelligence and machine learning tools for data-driven sorbent design. These methods enable high-throughput screening of materials prediction of performance metrics and identification of structure– property relationships. By combining experimental insights with computational advances carbon-based hydrogen storage platforms are expected to play a pivotal role in the next generation of energy storage systems. The paper concludes with a discussion on remaining challenges utilization scenarios and the need for interdisciplinary efforts to realize practical applications.

Hydrogen can play a significant role in Australian economy and Australia has set an ambitious goal to become a global leader in hydrogen industry as outlined in the National Hydrogen Strategy 2024. Hydrogen is an efficient energy carrier that can be used for both transporting and storing energy. Underground hydrogen storage (UHS) in aquifers depleted gas and oil reservoirs and salt caverns have been considered as a low-cost option for largescale storage of hydrogen. In this study a method for hydrogen storage in engineered (shallow) lenses is proposed where a lens is created in a very low permeability layered formation such as shales via opening the layers by a pressurised fluid. A preliminary overview of the Australian basins is presented focussing on the most suitable/obvious units for the purpose of creating engineered lenses for storage of hydrogen. Major engineering aspects of lenses such as size volume storage capacity storage time and hydrogen loss are reviewed followed by a Techno-Economic Analysis for the proposed hydrogen storage method. Initial modelling shows that up to 250 tonnes of hydrogen can be stored in shallow engineered lenses incurring a capital cost of 35.7 US$/kg and total annual operational cost of 7 US$/kg making the proposed storage method a competitive option against salt and lined rock caverns. Finally Monitoring and Verification (M&V) as part of storage assurance practice has been discussed and successful examples are presented.

This study comprehensively reviews the state-of-the-art laboratory-scale fracture mechanics testing methods to assess their suitability for investigating stress-induced critical cracks and geochemically induced subcritical cracks in caprock during underground hydrogen storage. Subcritical crack propagation is primarily examined using empirical techniques such as double torsion and constant stress-rate methods. Both methods determine stress intensity factors and crack velocities without requiring crack length measurements. Comparatively the double torsion method provides advantages such as simple sample preparation and pre-cracking process continuous data acquisition and fracture toughness measurements which makes it more reliable for caprockrelated studies. The International Society for Rock Mechanics recommends four standard methods for critical crack propagation to determine fracture toughness values. Chevron-notched specimens including the Chevron Bend specimen Short Rod specimen and Cracked Chevron Notched Brazilian Disk specimen exhibit higher uncertainty in fracture toughness data due to specimen size effects additional fixture requirements and undesirable crack formations. In contrast the Semi-Circular Bend specimen method is frequently employed due to its smaller specimen size simplified testing and well-balanced dynamic forces. Despite these advancements studies on multiple cracking behaviour in caprock under subsurface hydrogen storage conditions remain limited. The conventional methods discussed in this review are primarily designed to function at ambient conditions making it challenging to replicate subsurface geochemical interactions. Future studies should focus more on developing new laboratory techniques and enhancing existing specimen configurations by incorporating specialised apparatus such as high-pressure cells and reaction chambers to implement typical subsurface conditions observed during underground hydrogen storage. Additionally more parametric studies on caprock samples are recommended to generate a comprehensive dataset on subcritical and critical crack propagation and validate the reliability of these testing methods for underground hydrogen storage applications.

Tilos a Greek island in the Mediterranean Sea hosts a pioneering hybrid energy system combining an 800-kW wind turbine and a 160-kWp photovoltaic (PV) field. The predominance of wind power makes the energy production of the island almost constant during the year while the consumption peaks in summer in correspondence with the tourist season. If the island wants to achieve complete selfsufficiency seasonal storage becomes compulsory. This study makes use of measured production data over 1 year to understand the best combination of renewable energy generation and storage to match energy production with consumption. A stochastic optimization based on a differential evolution algorithm is carried out to showcase the configuration that minimizes the levelized cost of required energy (LCORE) in different scenarios. System performance is simulated by progressively increasing the size of the storage devices including a combination of Lithium-ion batteries and power-to-gas-topower (P2G2P) technologies and the PV field. An in-depth market review of current and forecasted prices for RES and ESS components supports the economic analysis including three time horizons (current and projections to 2030 and 2050) to account for the expected drop in component prices. Currently the hybrid storage system combining BESS and P2G2P is more cost-effective (264 €/MWh) than a BESS-only system (320 €/MWh). In the mid-term (2030) the expected price drop in batteries will shift the optimal solution towards this technology but the LCORE reached by the hybrid storage (174 €/MWh) will still be more economical than BESS-only (200 €/MWh). In the long term (2050) the expected price drop in hydrogen technologies will push again the economic convenience of P2G2P and further reduce the LCORE (132.4 €/MWh).

Hydrogen (H2) will play a vital role in the global shift towards sustainable energy systems. Due to the high cost and challenges associated with storing hydrogen in large quantities for industrial applications Underground Hydrogen Storage (UHS) in geological formations has emerged as a promising solution. Clay minerals abundant in subsurface environments play a critical role in UHS by providing low permeability cation exchange capacity and stability essential for preventing hydrogen leakage. However microorganisms in the subsurface particularly hydrogenotrophic species interact with clay minerals in ways that can affect the integrity of these storage systems. Microbes form biofilms on clay surfaces which can cause pore clogging and reduce the permeability of the reservoir potentially stabilizing H2 storage and limiting injectivity. Microbial-induced chemical weathering through the production of organic acids and redox reactions can degrade clay minerals releasing metal ions and destabilizing the storage site. These interactions raise concerns about the long-term storage capacity of UHS as microbial processes could lead to H2 loss and caprock degradation compromising the storage system’s effectiveness. This mini review aims to cover the current understanding of the interactions between clay minerals and microorganisms and how these dynamics can affect the safe and sustainable deployment of UHS.

Hydrogen is a promising candidate for renewable energy storage and transportation due to its high energy density and zero carbon emissions. Its practical applications face challenges related to safe efficient storage and release systems. This review article investigates advanced nanostructured materials for hydrogen storage including metal acetylide and cyanide complexes BN-doped γ-graphyne nanotubes (γ-GNT) lithium-phosphide double helices and Ni-decorated carbon-based clusters. Density Functional Theory (DFT) based computations are used to analyze binding energies thermodynamic stability and adsorption mechanisms. Ni-decorated C12N12 nanoclusters demonstrate enhanced storage capacities binding up to eight H2 molecules with a favorable N-(μ-Ni)-N configuration. Lithium-phosphide double helices show potential for 9.6 wt% hydrogen storage within a stable semiconducting framework. Functionalization of γ-GNT with OLi2 at boron-doped sites significantly enhances storage potential achieving optimal hydrogen binding energies for practical applications. Additionally metal acetylide and cyanide complexes stabilized by noble gas insertion display thermodynamically favorable hydrogen adsorption. These results highlight the potential of these functionalized nanostructures for achieving high-capacity reversible hydrogen storage. The nanostructures in this study such as γ-graphyne nanotubes (γ-GNT) lithium-phosphide double helices metal acetylide and cyanide complexes and Ni-decorated carbon-based clusters are selected based on their ability to exhibit complementary hydrogen adsorption mechanisms including physisorption and chemisorption. γ-GNT offers high surface area and tunable electronic properties ideal for physisorption enhanced by heteroatom doping. Lithium-phosphide double helices facilitate Kubas-like chemisorption through unsaturated lithium centers. Metal acetylide and cyanide complexes stabilize hydrogen adsorption via charge transfer and conjugated frameworks while Ni-decorated clusters combine polarization-induced physisorption. These materials represent a strategic approach to addressing the challenges of hydrogen storage through diverse and synergistic mechanisms. The review also addresses challenges and outlines future directions to advance hydrogen’s role as a sustainable fuel.

The purpose of this Hydrogen Pipeline System COP is to provide guidance based on current knowledge for the design construction and operation of transmission pipeline systems transporting gaseous hydrogen or blends of hydrogen and hydrocarbon fluids.<br/>The objective of the code is to provide guidance for the safe reliable and efficient transportation and storage of hydrogen in transmission pipeline systems that are required to conform to the AS(/NZS) 2885 series. The document also references adoption of other international codes where suitable guidance is available.<br/>This document is intended to be updated with revised design criteria and methods as research and experience improves the understanding of hydrogen service in transmission pipelines. Although the CoP may be further developed into a published standard in the future within the AS(/NSZ) 2885 series framework this current revision of the CoP is not equivalent to a formal published Australian standard. The document also includes expanded commentary and background information as an informative code of practice that is more extensive than is typically covered in a standard.

Hydrogen is a critical energy carrier in the transition to sustainable energy but its properties such as high diffusivity wide flammability range and low ignition energy present unique safety challenges during transportation. This study aims to improve on-road hydrogen transport safety by developing a dynamic traffic-dependent risk assessment framework for both Compressed Gaseous Hydrogen (CGH₂) tube trailers and Liquid Hydrogen (LH₂). A key advancement in this study is the use of dynamic occupancy data capturing variations in traffic density throughout the day instead of relying on average traffic density to estimate ignition source distribution. Additionally a qualitative Hazard and Operability (HAZOP) study was conducted for a potential central distribution terminal in Fort Saskatchewan Alberta Canada to systematically identify process hazards during the loading of hydrogen on-road carriers. Results reveal that the ignition probability for minor CGH2 leaks significantly increases with road occupancy rising from 0.003 at 0.1% to 0.149 at 5% emphasizing the importance of scheduling transport during off-peak hours Vapor Cloud Explosions (VCE) from LH2 extend up to 257 meters compared to 122.42 meters for CGH₂ underscoring the need for stricter land-use planning in densely populated areas. The analysis suggests prioritizing lower-traffic rural routes which exhibit lower release frequencies (e.g. 1.80E-05 per year) over high-traffic urban routes with higher release frequencies (e.g. 6.47E-05 per year).

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.