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Transitioning to a sustainable energy future necessitates innovative storage solutions for renewable energies, where hydrogen (H₂) emerges as a pivotal energy carrier for its low emission potential. This paper explores unlined rock caverns (URCs) as a promising alternative for underground hydrogen storage (UHS), overcoming the geographical and technical limitations of UHS methods like salt rock caverns and porous media. Drawing from the experiences of natural gas (NG) and compressed air energy storage (CAES) in URCs, we explore the viability of URCs for storing hydrogen at gigawatt-hour scales (>100 GWh). Despite challenges such as potential uplift failures (at a depth of approximately less than 1000 m) and hydrogen reactivity with storage materials at typical conditions (below temperatures of 100°C and pressures of 15 MPa), URCs present a flexible, scalable option closely allied with green hydrogen production from renewable sources. Our comprehensive review identifies critical design considerations, including hydraulic containment and the integrity of fracture sealing materials under UHS conditions. Addressing identified knowledge gaps, particularly around the design of hydraulic containment systems and the interaction of hydrogen with cavern materials, will be crucial for advancing URC technology. The paper underscores the need for further experimental and numerical studies to refine URC suitability for hydrogen storage, highlighting the role of URCs in enhancing the compatibility of renewable energy sources with the grid. • Detailed exploration of unlined rock cavern (URC) technology. • Analysis of URCs' potential for large-scale hydrogen storage. • Insights from historical use of URCs in compressed gas storage. • Examination of the opportunities and challenges in using URCs for hydrogen storage. [ABSTRACT FROM AUTHOR]

Promoting green hydrogen has emerged as a pivotal discourse in the contemporary energy landscape, driven by pressing environmental concerns and the quest for sustainable energy solutions. This paper delves into the multifaceted domain of C -Suite issues about green hydrogen, encompassing both technological advancements and policy considerations. The question of whether green hydrogen is poised to become the focal point of the upcoming energy race is explored through an extensive analysis of its potential as a clean and versatile energy carrier. The transition from conventional fossil fuels to green hydrogen is considered a fundamental shift in energy paradigms, with far-reaching implications for global energy markets. The paper provides a comprehensive overview of state-of-the-art green hydrogen technologies, including fuel cells, photocatalysts, photo electrocatalysts, and hydrogen panels. In tandem with technological advancements, the role of policy and strategy in fostering the development of green hydrogen energy assumes paramount significance. The paper elucidates the critical interplay between government policies, market dynamics, and corporate strategies in shaping the green hydrogen landscape. It delves into policy mechanisms such as subsidies, carbon pricing, and renewable energy mandates, shedding light on their potential to incentivize the production and adoption of green hydrogen. This paper offers a nuanced exploration of C -Suite issues surrounding green hydrogen, painting a comprehensive picture of the technological and policy considerations that underpin its emergence as a transformative energy source. As the global community grapples with the imperatives of climate change mitigation and the pursuit of sustainable energy solutions, understanding these issues becomes imperative for executives, policymakers, and stakeholders alike. [Display omitted] • The latest advancements in photo electrocatalysts and fuel cell technologies are reviewed. • The storage and transportation within the realm of green hydrogen energy were discussed. • Policy and strategy for fostering the development of green energy are proposed. [ABSTRACT FROM AUTHOR]

This review paper explores into the extensive realm of alkaline water electrolysis (AWE), a transformative technology for hydrogen production, offering profound insights and future prospects for sustainable growth. It embarks on this journey by explaining the fundamental principles, the application of Faraday's laws, electrolyzer design, and the intricate electrochemical processes transpiring at the cathode and anode. Subsequently, it investigates electrode materials, catalysts, membrane material and their recent developments, unveiling essential aspects of material selection and performance enhancement. The exploration extends to the domain of alkaline electrolyte solutions, where it provides a comprehensive overview of common electrolytes, the impact of concentration on system performance, and pioneering research on alternative electrolytes. Shifting focus towards large-scale systems and industrial applications, the paper unravels the economic feasibility, considerations regarding costs, and the transformative influence of alkaline water electrolysis on diverse industries. The final segment is dedicated to emerging trends and future directions. It casts light on recent breakthroughs and the potential for commercialization, presenting a vivid image of the evolving role of this technology in the sustainable energy landscape. The conclusive segment, this review offers a recapitulation of the key discoveries and insights presented throughout the paper, while delivering a critical evaluation of the present state of alkaline water electrolysis. It emphasizes the potential of the technology while recognizing critical research areas such as electrode materials, safety standards, scaling efficiency, flexible operation, and surface modification techniques. In the rapidly changing energy scenario, this paper stands as a testament to the dynamic nature of alkaline water electrolysis and its pivotal role in a sustainable energy future. • Identifying different alkaline water electrolysis (AWE) cell efficiencies and transport resistances. • Insights into recent development in electrodes, catalysts, and separator membranes materials. • Recognizing recently examined alkaline electrolytes. • Recent and emerging trends in AWE including the use of electromagnetic field and pulsating potential. • Perspectives of scaling up AWE and its industrial commercial applications. [ABSTRACT FROM AUTHOR]

Hydrogen is a kind of clean renewable energy with great development potential. However, traditional electrocatalytic water splitting methods often require high energy consumption and expensive catalysts, which limits their practical application. Transition metal selenides (TMSes), as a new type of hydrogen production materials from electrolytic water, have been the focus of research in recent years. The basic principle of electrochemical water cracking and the preparation of TMSes are reviewed in this paper. The electrocatalysts for hydrogen evolution, oxygen evolution and integral water cracking based on TMSes, including single metal selenides, binary metal selenides, and multinary mixed metal selenides, are discussed. Finally, the future research direction and the development prospect of TMSes electrocatalysts are prospected. • Eley-Rideal and Langmuir-Hinshelwood mechanisms were used to analyze the OER reaction mechanism. • The production and properties of transition metal selenides in recent years are introduced in detail. • In this paper, transition metal selenides are introduced from single TMSes, binary TMSes and multinary mixed TMSes. • The physical properties and electronic structures of transition metal selenides are described in detail. [ABSTRACT FROM AUTHOR]

This paper explores green hydrogen-based carbon dioxide (CO 2) hydrogenation for the production of oxygenates, presenting it as a pivotal strategy for mitigating carbon emissions and advancing sustainable energy solutions. The conversion of CO 2 into oxygenates through hydrogenation emerges as a promising avenue, particularly in the context of transportation applications where the storage of hydrogen poses challenges. The substitution of fossil diesel and gasoline fuels with green hydrogen-derived dimethyl ether, or methanol/ethanol, is advantageous from a life cycle analysis (LCA) CO 2 emission perspective even without the capture of the CO 2. However, the greatest sustainability appeal is contingent on the crucial aspect of capturing CO 2 when utilizing these fuels, which is an aspect currently absent in the literature. This narrative review comprehensively explores catalytic processes, mechanisms, sustainability perspectives, and the current state of research in this evolving area. It encompasses both the production of oxygenates through CO 2 hydrogenation and the subsequent utilization of these oxygenates in fuel cells or combustion systems, emphasizing the integration of CO 2 capture technologies. The paper contributes to the discourse surrounding the environmental and technological dimensions of energy storage ecosystems, providing a holistic view of their potential to foster sustainable energy solutions. [ABSTRACT FROM AUTHOR]

With the rapidly evolving geo-political landscape and unceasing advancements in technology, sustainable energy security is a very important topic. Research indicates that electrochemical energy systems are quite promising to solve many of energy conversion, storage, and conservation challenges while offering high efficiencies and low pollution. The paper provides an overview of electrochemical energy devices and the various optimization techniques used to evaluate them. The optimization techniques include linear regression, factorial design, the Taguchi method, artificial neural networks, filters, and a combination of such methods to improve these systems. To support the growing interest in research, the bulk of this study focuses on a review of the most promising and highly researched electrochemical energy devices, such as fuel cells, batteries, and supercapacitors. The paper also provides modest commentary on hydrogen production technologies, electrochemical reactors, and membrane separation technologies, amongst other technologies. Building on a previous paper by the authors of this paper on artificial intelligence in hybrid renewable energy systems with fuel cells, this work provides a comparative review of optimization techniques for supercapacitors by highlighting key findings based on model accuracy. A summary of the advantages and disadvantages of the different major optimization techniques is presented. The paper concludes that a combination of optimization techniques is used to overcome the drawbacks of individual techniques, with adaptive filters being the most widely studied. This paper presents studies on the Design of Experiments (DoE) with the goal of building a better understanding of the relationships that exist between different operating variables in various electrochemical devices. • The electrochemical systems can be optimized for better performance with high accuracy. • The optimization techniques used are either model-based or data-driven. • Linear regression and artificial neural networks are the most common techniques studied. • Hybrid models could be applied to enhance systems' accuracy and minimize errors. [ABSTRACT FROM AUTHOR]

With the growing demand for green technologies, hydrogen energy devices, such as Proton Exchange Membrane (PEM) fuel cells and water electrolysers, have received accelerated developments. However, the materials and manufacturing cost of these technologies are still relatively expensive which impedes their widespread commercialization. Additive Manufacturing (AM), commonly termed 3D Printing (3DP), with its advanced capabilities, could be a potential pathway to solve the fabrication challenges of PEM parts. Herein, in this paper, the research studies on the novel AM fabrication methods of PEM components are thoroughly reviewed and analysed. The key performance properties, such as corrosion and hydrogen embrittlement resistance, of the additively manufactured materials in the PEM working environment are discussed to emphasise their reliability for the PEM systems. Additionally, the major challenges and required future developments of AM technologies to unlock their full potential for PEM fabrication are identified. This paper provides insights from the latest research developments on the significance of advanced manufacturing technologies in developing sustainable energy systems to address the global energy challenges and climate change effects. • The AM technologies relevant to PEM fabrication are reviewed. • Corrosion performance of AM materials in the PEM working environment is presented. • The challenges and prospects of AM for PEM fabrication are discussed. • AM has the potential to revolutionize the fabrication of PEM systems. [ABSTRACT FROM AUTHOR]

A solid oxide electrolyzer cell (SOEC) is a promising clean energy technology due to with high conversion efficiency and the ability to directly produce syngas. This paper summarizes technical challenges of SOEC in terms of dynamic response, co-electrolysis and material degradation, and recent developments on the manufacturing technology, materials for each component, mathematical models, flow channel designs and reversible solid oxide fuel cells (RSOFCs). The model development and related research on SOECs are explored in this paper, encompassing sensitivity analyses, dynamic responses, structural degradation and practical applications. This paper aims to promote the future development of SOECs, including the improvement of electrolysis efficiency, lifetime and economic performance. • Technological limitations and recent developments for SOEC are reviewed. • The dynamic response, co-electrolysis and material degradation are discussed. • Component materials and their manufacturing techniques are summarized. • Multi-physics coupling models at different scales are highlighted. • Future research direction in materials and modeling are proposed. [ABSTRACT FROM AUTHOR]

There is a great desire to integrate multiple energy systems by forming low-carbon energy hubs. Among various energy platforms, the integration of power and gas networks via Power-to-Gas (PtG) technologies is introduced as a promising solution to enhance the flexibility of power grids and facilitate seamless adoption for high penetration levels of renewable energy resources. In addition, the production of green hydrogen from waste/inexpensive clean electricity has recently been identified as a potential means for large-scale energy storage, deployment of hydrogen mobility, and decarbonization of several processes that utilize hydrogen. As integrated hydrogen-based energy hubs (H 2 Hubs) attract more attention for widespread deployment, the security of such new platforms against various cyberattacks is also becoming a critical topic for investigation. This paper proposes a new data estimation technique, developed and integrated with H 2 Hubs scheduling models, for real-time optimal adaptive collection and organization of the system operating parameters for cybersecurity assessment. A new formulation is presented for the adaptive formation of a newly proposed concept, referred to as the system feasibility area , via real-time acquisition of the system operating information. The created feasibility areas are utilized for real-time post-occurrence detection of the bad scheduling data that is invisible to the existing cybersecurity layers. Numerical studies are conducted to demonstrate the efficacy and feasibility of the proposed model. The results demonstrate that the historical data can be adaptively collected in real time and successfully utilized to create feasibility areas to categorize the system operating points. • An optimal scheduling model is proposed for hydrogen-based energy hubs (H 2 Hubs). • A new data estimation method is developed and integrated with the scheduling model. • A new formulation is given for the adaptive creation of the feasibility area. • Simulation case studies are presented and discussed. [ABSTRACT FROM AUTHOR]

With the future of green energy relying on increases in green-energy production scale to support demand, placing importance on location selection for new energy production methods is going to be vital to secure a zero-carbon future. In this paper, a method called H2Locate is introduced to conduct a down selection sequence for identifying hydrogen production plant location within a defined region. Following the method, resource availability, energy availability, and social impact metrics are analyzed to understand which variables are most vital and what data must be obtained to achieve confidence in the selection of an implementation location. An illustrative example using Oklahoma as the region is produced to demonstrate the proposed method. The counties within Oklahoma are analyzed to identify potential subregions for implementing a hydrogen production plant. Excel-based software, The Probability of Hydrogen Implementation (PHI), using publicly available data regarding energy, resources, and social variables is utilized to carry out the proposed method. Considering the illustrative example with a 290 MW alkaline electrolysis facility, we find that Kay County, Johnston County, Caddo County, and the counties directly surrounding them are the most suitable locations in Oklahoma for the implementation given variables related to the desired energy, resource, and social metrics. • The H2Locate down selection method guides hydrogen production plant location selection. • Analyzes 7 hydrogen hub reports to identify key hydrogen industry variables. • Categorizes energy, feedstock, and social factor variables utilized in the H2Locate method. • An illustrative 290 MW alkaline electrolysis example in Oklahoma identified Kay, Johnston, and Caddo counties as prime locations. [ABSTRACT FROM AUTHOR]

This paper addresses the urgent need for efficient hydrogen storage methods in the context of combating climate change and transitioning to sustainable energy sources. Among various storage options, LiBH 4 is highlighted for its high volumetric and gravimetric energy densities, critical factors in determining its suitability for energy applications. However, challenges arise due to its high thermolysis temperature, which poses difficulties, especially in applications like automotive use where high temperatures are required. The commercial viability of LiBH 4 remains a significant obstacle due to the nascent stage of chemical hydride technology and the absence of large-scale production facilities. Environmental concerns also loom large, as the production of LiBH 4 relies on extensive mining of lithium and boron, known for their environmental impact. Furthermore, the economic feasibility of LiBH 4 as a hydrogen storage medium is questioned, given the substantial portion of total expenses attributed to hydrogen costs, affecting all methods except those based on fossil fuels or electricity. Nevertheless, there is optimism that with technological advancements and improved infrastructure, the costs associated with LiBH 4 and hydrogen storage overall may decrease over time. In conclusion, while LiBH 4 presents promising energy density characteristics, its practical implementation faces challenges such as high production costs, environmental concerns, and technological limitations. Overcoming these obstacles is crucial for realizing a sustainable and carbon-free energy landscape driven by hydrogen. • LiBH 4 shows promise for high energy density storage but faces obstacles high production costs and environmental concerns. • A comprehensive decision matrix analysis showcases the strengths and weaknesses of various hydrogen storage options. • LiBH 4 may find applications in small-scale personal storage due to its safety and energy density. [ABSTRACT FROM AUTHOR]

Hydrogen energy, characterized by its high calorific value and sustainability, represents a secondary clean energy source. It is predominantly stored, transported, and utilized through pipeline networks. However, a comprehensive optimization approach for the design for the ground pipeline network of hydrogen storage is currently lacking. This paper embarks on a systematic exploration of the layout, station type and parameter design for the ground pipeline network of hydrogen storage. Addressing various application perspectives, the study constructs two distinct pipeline network structures: the Star-Star Global Optimization Model (SSGO-Model) and the Star-Tree Global Optimization Model (STGO-Model). Three cases are discussed under six different constraint scenarios. These scenarios focus on layout optimization, variable capacity layout optimization, and the overall optimization of layout and parameters. An overall optimization strategy is proposed to solve the models. A detailed analysis of the iteration process, layout schemes, station and pipeline constraints, investment, and flow parameters of the pipeline network in the optimization results is presented. Through systematic analysis, the correctness and effectiveness of the model are verified, demonstrating the variability of optimization results under different topological structures and constraint conditions. Moreover, when conducting integrated optimization, the total investment is minimized, proving its superiority. The findings demonstrate the applicability of these models in guiding the construction for the ground pipeline network of hydrogen storage, thereby fostering the advancement of hydrogen storage technology. Concurrently, this research contributes significantly to the development of hydrogen energy, offering strategic insights and practical solutions for its efficient deployment. • Integrated optimization model for hydrogen storage ground pipeline network. • The model considers layout, station type and parameter design. • Overall optimization strategy is proposed. • Three cases verify optimization model. [ABSTRACT FROM AUTHOR]

Liquid organic hydrogen carriers (LOHC) can be used as a lossless form of hydrogen storage at ambient conditions. The storage cycle consists of the exothermic hydrogenation of a hydrogen-lean molecule at the start of the transport, usually the hydrogen production site, becoming a hydrogen-rich molecule. This loaded molecule can be transported long distances or be used as long-term storage due to its ability to not lose hydrogen over long periods of time. At the site or time of required hydrogen production, the hydrogen can be released through an endothermic dehydrogenation reaction. LOHCs show similar properties to crude oils, such as petroleum and diesel, allowing easy handling and possibilities of integration with current infrastructure. Using this background, this paper reviews a variety of aspects of the LOHC life cycle, with a focus on currently studied materials. Important factors such as the hydrogenation and dehydrogenation requirements for each material are analysed to determine their ability to be used in current scenarios. Toluene and dibenzyltoluene are attractive options with promising storage attributes, however their dehydrogenation enthalpies remain a problem. The economic feasibility of LOHCs being used as a delivery device were briefly analysed. LOHCs have been shown to be the cheapest option for long distance transport (>200 km), and are cheaper than most at shorter distances in terms of specifically transport costs. The major capital cost of an LOHC delivery chain remains the initial investment for the raw materials and the cost of equipment for performing hydrogenation and dehydrogenation. Finally, some studies in developing the LOHC field were discussed, such as microwave enhancing parts of the process and mixing LOHCs to acquire more advantageous properties. • Efficient hydrogen storage solution for sustainable energy transportation and storage. • Enables safe and cost-effective hydrogen transportation and distribution networks. • Promotes renewable energy integration through versatile and scalable storage capabilities. • Facilitates decarbonization efforts by enabling long-term, stable hydrogen supply chains. [ABSTRACT FROM AUTHOR]

In the contemporary global discourse on environmental and developmental issues, the dual challenges of sustainable green energy and water supply stand paramount. These elements are vitally intertwined with the socio-economic vitality of the world. Notably, regions plagued by freshwater scarcity are increasingly turning to desalination which consists of a reliable and unconventional water source. The intersection of renewable energy with desalination and water purification processes presents a compelling synergy. This approach is particularly pertinent in areas where freshwater shortages coexist with abundant solar energy availability. Additionally, these technologies boast the advantage of low operational and maintenance costs. This paper delves into the design, optimization and financial analysis of a novel, standalone hybrid energy system, integrating photovoltaic and fuel cell technologies, for an agriculture farm situated in Kairouan, Tunisia. Unlike conventional systems, this model foregoes battery storage in favour of hydrogen storage, generated through water electrolysis powered by solar energy. This system harnesses solar energy for direct electrical power generation and hydrogen gas production. A segment of the generated electricity is allocated to electrolysis for green hydrogen production. In times of solar unavailability, the stored hydrogen is reconverted to electricity via a fuel cell. An intriguing aspect of this system is the utilization of saline well water, which, due to its high salt content, necessitates purification through desalination to prevent damage to the electrolysis unit and to render it suitable for agricultural irrigation. [Display omitted] • The production of green hydrogen, water and electricity for agriculture farm in Tunisia is analyzed. • The Levelized cost of green hydrogen produced in the PV farm is 2.25 €/kg. • A PV hydrogen Farm station with a capacity of 140 kW produces 1991 kg of green hydrogen and 235 MW h of electricity yearly. [ABSTRACT FROM AUTHOR]

A dedicated grid-tied offshore hybrid energy system for hydrogen production is a promising solution to unlock the full benefit of offshore wind and solar energy and realize decarbonization and sustainable energy security targets in electricity and other sectors. Current knowledge of these offshore hybrid systems is limited, particularly in the integration, component control, and allocation aspects. Therefore, a grid-integrated analytical model with a power dispatch allocation strategy between the grid and electrolyzer for the co-production of hydrogen from the offshore hybrid energy system is developed in this paper. While producing hydrogen, the proposed offshore hybrid energy system supplies a percentage of its capacity to the onshore grid facility, and the amount of the electricity is quantified based on the electricity market price and available total offshore generation. The detailed controls of each component are discussed. A case study considers a hypothetical hybrid offshore energy system of 10 MW situated in a potential offshore off the NSW of Australia based on realistic metrological data. A grid-scale proton-exchange membrane electrolyzer stack is used and a model predictive power controller is implemented on the distributed hydrogen generation scheme. The model is helpful for the assessment or optimization of both the economics and feasibility of the dedicated offshore hybrid energy farm for hydrogen production systems. • Modeling of a grid-integrated analytical model of an OHES for hydrogen co-production. • Development of a power dispatch allocation strategy for the proposed OHES. • Development of detailed controls of each component used in the proposed OHES. • Demonstrations of a case study considering 10 MW OHES situated in offshore off the NSW of Australia. [ABSTRACT FROM AUTHOR]

To address the pressing need for sustainable energy solutions, hydrogen has emerged as a "zero-emission" energy source with vast potential in diverse sectors like manufacturing, transportation, and electricity generation. However, the realization of a hydrogen economy hinges on the development of safe and stable technologies and materials for hydrogen storage and transport. This paper presents a comprehensive review of the latest advancements in hydrogen storage systems, with a particular focus on porous materials. Notably, porous carbon materials derived from biomass waste have garnered attention due to their exceptional qualities. These include abundant and easily accessible raw materials, simplified production processes, adjustable characteristics, cost-effectiveness, low mass density, high specific surface area and porosity, structural diversity, and sustainable regeneration. These attributes position them as promising candidates for further exploration in hydrogen storage devices, particularly for achieving high H2 uptake capacities. The feasibility of utilizing both plant- and animal-based biomass porous carbons is examined, encompassing activated porous carbons, heteroatom doped porous carbons, and their composites, as pivotal components for the development of porous carbon storage devices. The synthesis and characterization of each form, along with their respective hydrogen storage capacities, are highlighted. While each material exhibits promise, it is important to note that they do present certain technological drawbacks. Addressing these limitations through further research and development is crucial to unlocking their full potential for future applications in the burgeoning hydrogen economy. [Display omitted] • Unique features of Biomass-derived carbon materials for hydrogen storage capacity. • Critical overview and key lessons from non-biomass derived materials. • Carbon materials from organic waste bridge hydrogen storage to the future economy. • Biomass-based carbon materials are signalling a need for further investigation. [ABSTRACT FROM AUTHOR]

In this paper, certain issues envisaged in the framework of development of design methodology for intelligent autonomous distributed hybrid power complexes (ADHPC) with green hydrogen and energy storage, functioning in grid mode and in the mode of interaction with the global (national) grid (GN) have been solved. Depending on their energy deficit or surplus, relative to the global grid, ADHPCs can operate as a load or as an energy source, respectively, as follows: based on the analysis of the energy balance management process in the ADHPC, a reasonable choice of the structure of the system of accumulation and distribution of power flows (SADCF) was made from the point of view of increasing the reliability of its functioning and ensuring the physical feasibility of the energy balance management process in this structure, i.e. keeping the actual power consumption of the consumers close to the required rated power at each given time t. This is achieved by including a condenser connected to the SADCF system on its assembly and distribution bus and a storage system BS with double-level ((BS1, BS2), double-circuit ((BS1(1), BS1(2)), (BS2(1), BS2(2))) structure, whereby: BS1of the level 1 - to manage the capacity balance in the SADCF under normal ADHPC regime and the variation of green hydrogen and consumption capacities within their confidence intervals assessed at the design stage; BS2 of the level 2 - to coordinate ADHPC and GN modes of operation and to control, together with BS1 of the level 1, GN, diesel generator (DG), the power balance in the SADCF when the ADHPC fails and when RES and consumption power are outside their confidence intervals; alternating charge/discharge operation of the parallel circuits will extend the life of the BS system; – a comprehensive definition of optimal ADHPC system situational energy balance management task is formulated. [ABSTRACT FROM AUTHOR]

This paper proposes a novel solar-based polygeneration system for simultaneous power generation, desalination, hydrogen-production, and refrigeration. The system integrates parabolic trough solar collectors, multi-effect distillation, polymer electrolyte membrane electrolyzer, Kalina cycle, organic Rankine cycle, Brayton cycle, and ejector cooling. Solar energy and waste heat from the Brayton cycle provide energy input. Power generation is achieved via the Brayton, Kalina, and organic Rankine cycles. The multi-effect distillation unit produces freshwater while the electrolyzer generates hydrogen. The ejector system supplies cooling. A comprehensive steady-state energy and exergy analysis evaluates the thermodynamic performance. The system attains 32.269 MW net power output and ejector COP of 0.3193. The overall energy and exergy efficiencies are 38.45% and 35.64%, respectively. The combustion chamber exhibits maximum exergy destruction. Exergoeconomic analysis determines associated costs and investment feasibility. Integrating multiple technologies into a system with solar input enhances efficiency, sustainability, and environmental benefits. • Presents novel solar multi-generation system integrating power, hydrogen, water and cooling generation • Validated methodology analyzes thermodynamic performance providing insights on efficiencies • Exergy destruction analysis identifies optimization opportunities in integrated solar systems • Showcases potential of intricate integration of solar, desalination, hydrogen and power for sustainable energy • Modular and scalable system design enables flexibility for different applications and demands [ABSTRACT FROM AUTHOR]

Applying clean energy is one of the feasible paths to achieve the "dual carbon target". Hydrogen energy, as an efficient and clean energy, is a new growth point for creating industrial transformation and upgrading. Ammonia is recognized as a zero-carbon hydrogen energy carrier, and utilizing hydrogen through hydrogen production from ammonia decomposition is one of the effective ways to safely store, transport and utilize hydrogen energy. In addition, there are many methods to realize the hydrogen production from ammonia, among which the method based on the combination of non-thermal plasma (NTP) and catalyst can reduce the reaction temperature, significantly improve ammonia (NH 3) conversion efficiency and hydrogen energy yield. As one of the methods with good application prospects, the interaction between NTP and catalyst in this method is complicated, and the efficiency of hydrogen production from ammonia is also affected by various factors, which restricts application of the method. In order to provide new ideas for the development and commercial application of NTP-catalytic technology for ammonia decomposition, this paper reviews the progress of NTP-catalytic hydrogen production from ammonia based on a systematic and integrated literature review methodology, analyses the effects of process parameters, temperature, catalyst, and other factors on the efficiency of plasma-catalytic ammonia decomposition, and discusses the plasma source and the mechanism of plasma-catalytic ammonia decomposition reaction. Finally, the opportunities and challenges of this plasma catalysis method are described. • The progress of low-temperature plasma-catalytic NH 3 decomposition was summarized. • Three factors affecting plasma-catalytic NH 3 decomposition reaction were analyzed. • The mechanism of plasma-catalytic NH 3 decomposition were presented. • Opportunities and challenges for plasma-catalytic NH 3 decomposition were outlined. • Low-temperature plasma catalysis can significantly improve the NH 3 conversion. [ABSTRACT FROM AUTHOR]

The ongoing transition from fossil fuel-based electricity generation toward green energy relying on the intermittent renewable energy sources indispensably requires development of novel energy conversion and storage methods. Depending on a particular location and local resources, pumped storage, lithium- or sodium-ion batteries, compressed air energy storage, as well as the so called power-to-gas (P2G) technologies may be applied. Taking into account the abundant solar energy resources available in the northwestern China, such as Ningxia hui autonomous region, and local water resources coming from the Yellow River, a power-to-hydrogen (P2H2) distributed energy conversion system is proposed in this paper, which is based on a high-efficiency reversible Solid Oxide Cell (rSOC). The conducted studies comprise tests with simulated current based on the actual photovoltaic power station data, and with usage of the as-obtained Yellow River water for the electrolysis mode without any pretreatment. It is documented that the reversible operation is beneficial, and the tested cell can operate for a prolonged time. Of importance, Na, Ca, Mg, and Si elements remain in an evaporator, and do not contaminate the cell, while higher than the initial boron concentration can be found in the condensed exhaust gases. The respective operational parameters of the system correspond to an electrolysis current density loading up 433.3 mA cm−2 for 4 h, as well as fuel cell operation mode with a current density of 8.3 mA cm−2 for 12 h. It is found that the average voltage losses in the electrolysis cell and fuel cell mode are 0.27 %/cycle and 0.886 %/cycle, respectively, indicating that the lifetime of the cells can be more than 800 h. The reported studies demonstrate validity of applying rSOC-based P2H2 system, especially if abundant photovoltaic power and water resources are available. [Display omitted] • The Yellow River water was utilized by rSOC for the first time. • The designed test current was modeled with local photovoltaics. • The P2H2 nearby consumption system can reversibly operate for over 800 h. • The degradation rates in SOFC mode are lower than those in SOEC mode. • The Yellow River water has no significant effect on the degradation rate. [ABSTRACT FROM AUTHOR]

The global energy issue is undergoing transformation owing to various factors, such as climate change and geopolitics. In the long term, the primary pathways to achieve sustainable energy development remain the clean energy and global cooperation. As the largest energy consumption centers, the Asia Pacific and North America possess complementary energy profiles and developmental needs for cooperation. This paper analyses various electricity or hydrogen transmission technologies suitable for the Pacific Rim energy system. The liquid hydrogen superconducting energy pipelines possess the potential to fulfill the demands of long-distance and large-scale energy transmission. Building upon this technology, a super energy pipeline project connecting East Asia and North America across 12 time zones was proposed. It is composed of pipelines and relay energy stations, which can realize large-scale storage and transportation of renewable energy as well as the diversified energy supply at terminals. The techno-economic evaluation of the project has been comprehensively conducted, and the investment can be recovered within 10 years. The project is expected to boost the progress of renewable energy, ensure regional energy security and promote the sustainable development of global energy. [Display omitted] • Proposes cross-continental energy transmission scheme for Pacific Rim. • Highlights the potential of liquid hydrogen superconducting energy pipelines. • Identifies the future requirements for the energy storage and transmission. • Presents a review of the existing global energy mix. [ABSTRACT FROM AUTHOR]

This paper investigates an innovative study on the performance of a hybrid condensing boiler-fuel cell micro-cogeneration system for single residential applications. It combines experimental and dynamic numerical investigations including renewable energy for green hydrogen production and solid storage. Basing on the hourly measurements for a typical winter day, a dynamic model was developed and validated against different home heating need. Highlighting the influence home energy needs on fuel cell operating mode, it shows that single homes with low energy demand led to reduce the fuel cell's yearly operation below 50 %. In low-energy homes, a reduction in fuel cell size led to an increase in yearly operation to 60-70 % and achieved a 55 % electrical coverage rate. The integration of metal hydride hydrogen solid storage, powered by renewable sources, is emphasized. This setup increases heat demand, influencing fuel cell operation. In winter season, fuel cell operated for an average of 611 h, compared to 61 h in summer. System efficiency averaged 91 % annually, peaked at 95 % in summer, and sustained 93 % when both FC and condensing boiler were switched on. [Display omitted] • Modeling of a hybrid Boiler-Fuel Cell MCHP system for residential energy management. • Calibration of the FC-MCHP model using experimental data from a real MCHP unit. • Electrical and thermal coverage of the FC-MCHP unit with green hydrogen production and storage under different scenarios. • Strategies for optimal hydrogen consumption in in residential application. • Impact of solid-state hydrogen storage on FC-MCHP consumption and thermal management. [ABSTRACT FROM AUTHOR]

This paper examines the complex relationship between the role of H 2 , carbon emissions and their impact on global warming and the economy. Despite improvements in energy efficiency, fossil fuel consumption continues to increase. CO 2 from industrial activities at high temperatures, such as cement, iron, steel and glass production, have increased rapidly, resulting in an increase in the concentration of greenhouse gases in the atmosphere. These emissions accelerate climate change, leading to dangerous consequences such as increasing average atmospheric temperature and decreasing agricultural productivity. To combat this, it is advocated to reduce CO 2 emissions by using renewable energy sources such as hydroelectricity, biomass, wind solar energy. Current study also discusses carbon reduction methods, including oxy-fuel combustion capture, pre-combustion capture, and post-combustion capture. Despite their unique advantages and disadvantages, these methods play an important role in reducing CO 2 emissions from power plants. Additionally, the article highlights the importance of H 2 as a cornerstone in the development of synthetic fuels and future energy systems. H 2 from renewable sources holds the potential to use carbon-neutral synthetic liquid fuels and revolutionize transportation. Although traditional H 2 production methods are associated with emissions, sustainable H 2 production techniques can facilitate low-carbon fuel production. The article concludes by highlighting the importance of sustainable energy practices and the role of H 2 in reducing carbon emissions, highlighting research efforts to improve production methods, integrate renewable energy, and develop carbon capture technologies for a sustainable future. • Methods used in synthetic fuel production and sources of hydrogen production. • Carbon capture methods and their comparative discussion. • The importance of hydrogen production in synthetic fuel production and future plan. [ABSTRACT FROM AUTHOR]

Hydrogen is expected to be a game changer in the fight against climate change, being able to support the clean energy transition through a variety of roles: decarbonizing different hard-to-abate industrial sectors (such as steel, cement production) and transport (in long haul vehicles, maritime transport, and aviation), direct use as a fuel, chemical feedstock or in the form of synthetic fuels, and providing the ability to integrate with hybrid energy systems and renewables, enhancing energy storage and tapping the full potential of renewable energy sources. As a consequence, a substantial expansion in hydrogen production, due to rise in the demand, is expected by 2050, with all the generation coming from zero-carbon processes (electrolysis/thermochemical cycles using clean electricity and heat) or from a low-carbon production process using steam methane reforming with carbon capture and storage. Nuclear energy can be capitalized on both electricity and heat to provide a clean and reliable source of hydrogen through various processes. There are currently various demonstration projects undergoing in several countries to showcase the use of nuclear energy to produce clean hydrogen, considering both the current reactor fleet and advanced reactors. This paper provides an overview of these projects, giving an insight on the potential use of nuclear energy for hydrogen production and the current status of existing projects. It also highlights the activities of the International Atomic Energy Agency on technical and economic assessment of hydrogen production using nuclear energy for near term deployment. • Hydrogen is anticipated to be a game-changer in the fight against climate change. • Nuclear energy is positioned favourably to serve the developing hydrogen economy. • A single 1000 MW nuclear reactor could produce more than 200,000 t of H2 per year. • Several countries are considering nuclear hydrogen demonstration projects. • The IAEA has multiple resources available for nuclear hydrogen production. [ABSTRACT FROM AUTHOR]

Energy consumption was skyrocketing along with fast economic development as well as continuous global population growth. Furthermore, environmental concerns about greenhouse gas emissions were also increasing, which indicated that these issues could be resolved by the development and utilization of renewable and clean energy. Among many renewable kinds of energy, hydrogen was considered the cleanest generating water because it was the only combustion product, allowing for truly zero pollutant emissions. As a result, developing efficient hydrogen generation technologies that utilized biomass feedstock, and ensured clean energy produced with low-carbon emissions was critical in helping fight against global warming as well as obtain waste recovery. In this paper, recent investigation advances in the generation of hydrogen from biomass pyrolysis and gasification were comprehensively reviewed in this regard. Also, the most recent studies on biomass pyrolysis and gasification in the use of biomass waste to produce hydrogen, with an emphasis on technical problems, efficiency, and mechanism were summarized. Following that, challenges and opportunities were presented for enhancing the efficiencies of the process and the quality of the products, which was significant to obtain sustainable and green development. Importantly, even though several advances and innovations in generating hydrogen from biomass were made using existing technologies, more scientific advances were needed to make it economically competitive as well as environmentally friendly for industrial production on large scale. Overall, the entire article gives a consolidated overview of the optimal condition suggested for superior H 2 yield, and %volume from various biomass. • Hydrogen (H 2) is known as the green and clean fuel for decarbonization strategies. • Biomass wastes are considered potential renewable sources for H 2 production. • Recent advances in pyrolysis and gasification for H 2 production are scrutinized. • Opportunities and challenges of H 2 production from biomass wastes are discussed. [ABSTRACT FROM AUTHOR]

Considering the escalating global warming and its severe consequences, the exploitation of hydrogen, an eco-friendly energy carrier, is gaining great interest. This paper comprehensively reviews the most common hydrogen production, storage, transportation and utilization processes, while their effectiveness is explored from energy, water, economic and environmental perspectives. Their main characteristics, advantages, shortcomings and challenges are discussed as well. The research reveals that the hydrogen's water footprint, energy consumption, carbon emissions, and cost vary significantly depending on the specific technologies used throughout its life cycle, from production to end use. For instance, fossil fuel-based hydrogen production methods, such as steam methane reforming, offer elevated energy performance and cost-effectiveness, but have a significant carbon footprint. In contrast, water electrolysis is environmentally friendly, but requires more water and has lower energy efficiency. Besides, high-pressure containers are the preferred method for hydrogen storage, while liquid and solid storages are better suited for high-energy-density applications. Regarding hydrogen transportation, pipelines are effective over long distances, whereas tankers are convenient for short distances. Furthermore, fuel cells are more energy, carbon and water efficient when using hydrogen as fuel, but they are generally more expensive than internal combustion engines. [Display omitted] • Hydrogen production, storage, transportation and utilization methods are reviewed. • Their energy efficiency, water use, cost, and environmental impact are explored. • Key recommendations to boost the utilization of hydrogen systems are outlined. • Fossil fuel-based technologies are more energy-efficient and cost-effective. • Renewable-based processes are more environmentally friendly but water-intensive. [ABSTRACT FROM AUTHOR]

Electrocatalytic, photocatalytic, and photoelectrocatalytic water splitting provide promising pathways for converting electricity and light energy into sustainable hydrogen energy. The rational design and preparation of electrocatalytic, photocatalytic, and photoelectrocatalytic materials are of great significance for water splitting. Based on NiWO 4 , composite catalysts can significantly enhance the catalytic activity and performance of water splitting, especially in the fields of photocatalytic, electrocatalytic, and photoelectrocatalytic hydrogen and oxygen production, as well as overall water splitting. Due to its abundant active sites, excellent conductivity, and synergistic effects with other materials, the design and preparation of NiWO 4 -based composite catalysts are favored by researchers. Currently, there is little information available on the universality of catalytic materials in these three areas. This paper reviews the universality of NiWO 4 -based composite catalysts in the fields of electrocatalytic, photocatalytic, and photoelectrocatalytic water splitting, as well as their universal applications in promoting hydrogen production, oxygen production, and overall water splitting, comprehensively elucidating the mechanism and application of NiWO 4 -based composite catalysts in water splitting and boldly envisioning their broad development prospects. • Hydrogen production have investigated by light, electricity, and photoelectricity chemical electrolysis. • Nickel tungstate-based composite materials are used as the suitable catalysts for hydrogen production. • The mechanisms and applications of NiWO 4 -based composite catalysts in water splitting are present in detail. • The superiority of NiWO 4 -based composite catalyst for water splitting are demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, an integrated system is proposed for the production of turquoise hydrogen from methane cracking using solar energy. The produced hydrogen and carbon by-products are used in fuel cells to generate clean electricity. Syngas is produced through power generated via photovoltaics, using a solid oxide electrolyzer cell (SOEC). The SOEC co-electrolyzes the exhaust CO 2 from the direct carbon fuel cell, along with H 2 O. The resulting syngas is subsequently converted into methanol. The system is modelled using Aspen Plus to obtain the thermodynamic evaluation. Mass, energy, entropy, and exergy balances are performed over the system's units. The energy and exergy efficiency of the subsystems is determined, with solar methane cracking system achieving energy and exergy efficiencies of 82.2% and 92.5%, respectively. The overall system produces methanol and generates 7.71 MW of electricity with the overall energy and exergy efficiencies of 40.6% and 37.5%, respectively. • Energy and exergy analysis of an integrated methane cracking system. • Carbon black by-product is used in a direct carbon fuel cell. • Produced CO 2 is co-electrolyzed with water to produce syngas. • Processes modelled on Aspen Plus to obtain thermodynamic evaluation. • The proposed system has an energy and exergy efficiency of 40.6% and 37.5%, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

One of the reasons why renewable energies are so attractive compared to fossil fuels is their low environmental impact. In addition, geothermal power plants contribute tremendously to sustainable energy generation for cities despite their lower energy efficiency than fossil fuel plants. The multi-heat recovery will eliminate the applicability defect mentioned. Therefore, this paper studies a novel tri-generation schema with the maximum use of heat loss through a multi-heat recovery technique in two principal processes, namely waste heat-to-power and power-to-H 2 and -purified water. A double-flash binary cycle, Rankine cycle, electrolyzer unit, and reverse osmosis desalination system all play a part in the creation of this system. The technical feasibility of the system is scrutinized based on energy-exergy, environmental, sustainability, and exergoeconomic metrics and bi-objective optimization. Generally, 1st separator pressure made the strongest effect on the measured variables among decision variables. The increase in this parameter led to an upward-and-downward behavior of the net electricity and exergetic efficiency; while the cost of products experienced a converse trend. Also, the produced H 2 and purified water together with the tri-generation gain output ratio augmented. Changes were not observed in net electricity and purified water with the change in 2nd separator pressure, but the H 2 production rate changed significantly. Through bi-objective optimization, net electricity, purified water production rate, and total investment cost rate also significantly increase. Based on the optimum design mode, the CO 2 emission rate and the sustainability index are higher than under the base case design. • Using multi-heat recovery technique in two principal processes, namely, waste heat-to-power and power-to-H2 and -purified water. • Evaluation of system indices based on energy-exergy and exergoeconomic metrics and bi-objective optimization. • Exergetic efficiency, TGOR, and the cost of products improved by 5.19%, 109.52%, and 8.54%, separately, thanks to bi-objective optimization. [ABSTRACT FROM AUTHOR]

The majority of research in the carbon-based nanomaterials (CNMs) field has concentrated on the classification and synthesis of CNMs, with relatively few studies focusing on CNMs' roles in photocatalytic hydrogen production. CNMs have proven their potential as an effective addition to the appeal of photocatalytic hydrogen evolution because of their superior chemical and physical properties. This paper explores the recent advancements in photocatalytic hydrogen (H 2) production utilizing CNMs. As evidenced in the literature, carbon quantum dot (CQD)-sensitized titanium dioxide (TiO 2) can demonstrate to have a photocatalytic hydrogen generation activity of 472 mol g−1 h−1 and 1458 mol g−1 h−1 without and with loading metal co-catalyst (Pt). The optimum catalyst, 0.4 CQD/CdS, contributes to the highest H 2 production rate of 309 mmol g−1 h−1 (apparent quantum yield of 32.6%), which is 1.5 times greater than that of bare CdS. This would significantly accelerate the hydrogen production process. There are still challenges to reaching maximum photocatalytic hydrogen production, including low hydrogen storage. The overall price of hydrogen produced via photocatalysis is also higher because of the energy needed to store the hydrogen. Even though the problem is not directly related to the usage of CNMs, this restriction generates uncertainty and limits commercial investment. Given the rising demand for energy and the trend toward green power, it is recommended that extensive industrial uses of photocatalytic hydrogen produced by employing CNMs be investigated for better and more sustainable energy frameworks. • Recent advances in photocatalytic H 2 production are investigated utilizing CNMs. • The optimum catalyst, 0.4 CQD/CdS can produce the highest H 2 at 309 mmol g−1 h−1. • CQD-sensitized TiO 2 can generate 1458 mol g−1 h−1 photocatalytic hydrogen with Pt. • Photocatalytic H 2 production using CNMs should be investigated for industrial use. [ABSTRACT FROM AUTHOR]

In the modern world, zero-carbon society has become a new buzzword of the era. Many projects have been initiated to develop alternatives not only to the environmental crisis but also to the shortage of fossil fuels. With successful projects in automobile technology, hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector which will lead to zero carbon emission in the future. From the mid-20th century to the early 21st numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. Empirical data show positive results for various projects. Consequently, large companies are investing in various innovations undertaken by researchers under their supervision. Over time, the efficiency of hydrogen-fueled aircraft has improved but the lack of refueling stations, large production cost, and consolidated carbon market share have impeded the path of hydrogen fuel being commercialized. In addition, the Unmanned Aerial Vehicle (UAV) is another important element of the Aviation industry, Hydrogen started to be commonly used as an alternative fuel for heavy-duty drones using fuel cell technology. The purpose of this paper is to provide an overview of the chronological development of hydrogen-powered aircraft technology and potential aviation applications for hydrogen and fuel cell technology. Furthermore, the major barriers to widespread adoption of hydrogen technology in aviation are identified, as are future research opportunities. [Display omitted] • Hydrogen is extensively researched and acknowledged as a viable mainstream fuel option. • Hydrogen fuel is now being tested and utilized as a sustainable green fuel in the aviation sector. • Numerous countries and companies have funded multimillion projects to develop hydrogen-fueled aircraft. • Empirical data show positive results for various projects. • New engine modules have been designed to accommodate hydrogen fuel cells economically. [ABSTRACT FROM AUTHOR]

Simultaneous wastewater treatment and energy harvesting is attractive topic these days. A microbial fuel cell is an electrochemical device that can be used effectively for this purpose. Microalgae-based MFC is a novel approach to extracting sustainable and economical energy by incorporating photosynthesis with MFC. This paper uses artificial intelligence to identify the best operational factors of microalgae microbial fuel cell (MMFC). The proposed methodology integrates artificial neural network (ANN) modelling and forensic-based investigation algorithm (FBI). Yeast concentration (%) and wastewater concentration (%) are used as decision variables during the optimization process, whereas the objective function is simultaneously maximization of power density and COD removal. Based on the measured data, a ANN model is designed to simulate the power density and COD removal in terms of yeast and wastewater concentrations. Compared with ANOVA, the values of coefficient-of-determination are increased. For the power density model, the coefficient-of-determination in the prediction is increased from 0.7275 to 0.9783 by around 34%. Whereas for the COD removal model, the coefficient-of-determination in the prediction is increased from 0.8512 to 0.9 by around 5.7%. Then, using FBI, the best concentrations of yeast and wastewater are identified to increase power density and COD removal simultaneously. To prove the superiority of the proposed methodology, the optimal parameters and best performance are compared with an optimized performance by response surface methodology and measured data. The performance of MMFC is increased by 2.24%, thanks to the integration between ANN and FBI. • Artificial intelligence is used to model the performance of MMFC. • Forensic-based investigation algorithm (FBI) is used to optime the controlling factors. • Two controlling factors and two responses were considered. • The AI is effectively applied to model and optimize the performance of the MMFC. [ABSTRACT FROM AUTHOR]

Global population growth and the exponential rise in energy consumption have put immense strain on finite fossil fuel supplies and presented a danger to the environment. Waste may be converted into energy using sustainable biological method. Biohydrogen generation from lignocellulosic materials is a clean as well as environmentally friendly path for producing biofuels with a bright future. The advancement of biohydrogen advanced technologies has resulted in the emergence of new power generation, which is important for the long-term utilization of power. Due to the limited energy needs and cost involved, biohydrogen production has many benefits over photo-electrochemical or thermo-chemical methods. Although beneficial and favored, the hydrogen production from biomass and carbohydrate raw material has always been at the lab scale. The main aim of the article was to review the various biomass and biohydrogen from biomass. This paper also goes over the various methods for producing biohydrogen, including dark fermentation, photo-fermentation, combined dark and photo fermentation, bio-photolysis, and microbial electrolysis cells. Each form of production's methods, benefits and drawbacks, and variables affecting microbial electrolysis cell have been investigated. Based on the existing research, nanoparticles can play an essential role in strengthening this process in a sustainable basis, allowing for significant yields of biohydrogen to be achieved on a feasible scale. Due to this topic is still in its initial stages, further research is required to close the current gap in terms of practical applications and commercial viability. • Various sources and types of the plastic waste was discussed. • Occurrence and impact of plastic waste has been reviewed. • Different methods for the thermochemical conversion of plastic waste were elucidated. • Sustainable products from plastic waste were explored. • Circular Economy in handling of plastic waste were addressed. [ABSTRACT FROM AUTHOR]

The pressure on reducing greenhouse gas emissions has increased since the focus on climate change mitigation has grown. As the human development index is directly related to per capita energy consumption, sustainable energy production with reduced carbon footprint is the essential pathway for cleaner environment. Over numerous existing biological processes, hydrogen production via photo fermentation and photolysis of water is considered a more sustainable and economical method of hydrogen production. While both biological modes suffer from certain limitations, such as low yields and low production rates, practical implementation is still a long way off due to these limitations. The unique properties of nanomaterials (NMs) can help increase the efficiency of the biomass to biohydrogen process in significant ways. Applications of organic and inorganic nanoparticles in photocatalytic and photo fermentative hydrogen production is discussed in this paper. This review reports a wide range of applications of nanomaterials including the details of photo fermentative microorganisms and their mechanism of action. The maximum photo fermentative bio-H 2 production was reported in the presence of SiC–Fe 3 O 4 (3.02 mol H 2 /mol acetate), Ni (41 mol H 2 /mol sugar), graphite-C 3 N 4 (64.2 mol H 2 /mol sugar) whereas photocatalytic bio-H 2 yield was highest when Pd–Ni/CdS (54 mmol/g.h), Ni-MO/g-C 3 N 4 (1785 mmol/g.h) and CuO/TiO 2 (20.3 mmol/g.h) nanoparticles were employed. To design photocatalytic systems for practical and scalable use, the future research should be focused on deeper theoretical knowledge of mechanisms of light harvesting, ± charge separation and transport, surface biochemical reactions, semiconductor–liquid interactions, and reactor dynamics. [Display omitted] • Recent developments for improving water photolysis and photo-fermentation are reviewed. • Applications of organic and inorganic nanoparticles in hydrogen production are discussed. • The working principle and mechanism of hydrogen production are discussed. • The influence of key operating factors are presented. • Scope for future research was presented. [ABSTRACT FROM AUTHOR]

In the recent years Green to Green Energy Systems have gain tremendous interest because they are pollution free systems. In this frame, the present paper aims at investigating a Green to Green system coupling Photovoltaic, Wind and Fuel Cell. Furthermore, an analysis procedure is developed allowing to find the optimal configuration of coupling by assessing the output power in terms of the system parameters. Moreover, a case study on Lebanon is considered where three different regions that are Dahr El-Baidar, Klaiaat Akkar and Rayak Bekaa are studied. Results shows the flexibility and strength of the suggested procedure. Indeed, it has been shown that for Dahr El-Baidar it is suggested to adopt WFC system whereas for Klaiaat Akkar hybrid PVWFC is the optimal solution and PVFC is better for Rayak Bekaa. Furthermore, an economic based optimization is carried out. It was surprisingly found that from an economic standpoint and for a land area larger than 3000 m2 Rayak Bekaa is the optimal location for WFC hybrid system. • The work is performed within the frame of Green to Green (G2G) concept that combines green source to green storage. • Green sources are PV and Wind Turbine whereas the green storage system is fuel cell. • The developed model is applied to three different regions in Lebanon in order to find the best configuration. [ABSTRACT FROM AUTHOR]

This paper discusses the technical and economic feasibility of a renewable energy-based system, aimed to replace the traditional diesel engines implemented on a pushed and pusher bulk carrier barge. This barge has a challenging navigational route in the Nile River from Alexandria to Aswan and vice versa. It is scheduled to complete 30 trips annually while carrying 850 tons/trip. The system is based on photovoltaic panels, and was selected with its excess energy to be stored primarily in the form of H 2 gas through electrolysis, and batteries (i.e. Power to Gas technology) to be later converted back to electrical energy through fuel cells. Hence, an operation algorithm was formulated to optimize the performance of the system by defining operating modes that use solar energy, hydrogen energy, batteries, or hybrid energy coming from multiple sources that result in an internal rate of return (IRR) of 15.1% and overall efficiency of 57.9%. This high efficiency is due to the nature of water current that flows from south to north of Egypt, therefore, causing a significant reduction in power demand in the trip from Aswan to Alexandria that requires 11,980 kW h, compared to the trip from Alexandria to Aswan that requires 21,064 kW h. • Zero emission solution combining solar energy, hydrogen generation and fuel cell propulsion for a barge in Nile River. • Preparation to achieve the 7th goal of sustainable development ensuring green propulsion in Nile River cargo transport. • Efficient use of natural resources, solar energy and water current from south to north of Egypt. • Integrating electrolizer, fuel cell, solar energy pv, batteries, and hydrogen storage to form an autonomous barge. [ABSTRACT FROM AUTHOR]

In renewable-based microgrids, intermittency caused by some energy sources highlights the important role of energy storage systems. Nowadays, hydrogen and thermal energy storage are expected to play key roles in grid-scale applications, for facilitating effective penetration of clean energy sources. This paper, through a multilevel control framework for the energy management of a renewable and reversible solid oxide based microgrid, develops medium level controls accounting for the dynamic behaviour of storage systems. The storage systems considered are a hydrogen storage tank and a thermal energy storage based on phase change material technology. In particular, the proposed algorithm is helpful in the microgrid design phase as well as for clearly assessing high-level energy management strategies, since dynamic and transient behaviours of tanks during both charging and discharging phases are validated. In this way, top-level energy management strategies can be further refined and optimized in addition to a techno-economic design being pursued, primarily through shrinking the initial sizes of storages and thereby achieving significantly lower initial capital costs. For the analyzed microgrid, its feasibility is demonstrated by reducing by as much as 40% the size of the hydrogen tank and by up to 20% the energy capacity of the thermal storage. Finally, the proposed medium level control in a multilevel algorithm framework for a hydrogen-based microgrid is also seen to be fruitful for avoiding waste energy, which can be beneficial against the background of distributed energy systems acting in virtual power plants. • An rSOC-microgrid relying on renewables and innovative storages (i.e., HST and PCM-TES). • Multilevel control strategy checking storages resiliency in terms of energy satisfaction. • HST and TES sub-models considering transient phases for charging and discharging. • Scenario analyses aimed at optimizing both energy and economic aspects of energy storages. [ABSTRACT FROM AUTHOR]

This paper introduces a Techno-Economic Assessment (TEA) on present and future scenarios of different energy storage technologies comprising hydrogen and batteries: Battery Energy Storage System (BESS), Hydrogen Energy Storage System (H 2 ESS), and Hybrid Energy Storage System (HESS). These three configurations were assessed for different time horizons: 2019, 2022 and 2030, under both on-grid and off-grid conditions. For 2030, a sensitivity analysis under different energy scenarios was performed, covering other trends in on-grid electric consumption and prices, CO 2 taxation and the evolution of hydrogen technology prices from 2019 until 2030. The selected case study is the Research Park Zellik (RPZ), a CO 2 -neutral sustainable Local Energy Community (LEC) in Zellik, Belgium. The software HOMER (Hybrid Optimisation Model for Electric Renewable) has been selected to design, model and optimise the defined case study. The results showed that BESS was the most competitive when the electric grid was available among the three possible storage options. Additionally, HESS was overall more competitive than H 2 ESS-only, regardless of the grid connection mode. Finally, as per HESS, hydrogen was proved to play a complementary role when combined with batteries, enhancing the flexibility of the microgrid and enabling deeper decarbonisation by reducing the electricity bought from the grid, increasing renewable energy production and balancing toward an island operating mode. • Assessment of hybrid energy storage systems for future energy scenarios. • Sensitivity analysis with different technical, economic, and environmental KPIs. • Analysis of the effects of the connection and capacity access to the electric grid. • Application to a real case study: a CO2-neutral Local Energy Community. [ABSTRACT FROM AUTHOR]

The energy sector is actively transitioning towards climate-neutral solutions, emphasizing advancements in clean power generation technologies. Cogeneration systems based on solid oxide fuel cells (SOFC) currently exhibit higher electrical efficiencies than conventional plants, but their operation can still be improved. One of the approaches to increase its efficiency is implementing anodic off-gas recirculation. In this work, a numerical model of a 10 kW SOFC installation with anodic gas recirculation was analyzed using Aspen HYSYS software. System fueled with three alternative fuels (natural gas, hydrogen, and ammonia) was tested. In this paper it was proven that anode-off gas recirculation improves the electrical and total efficiency of the system for each fuel type. The cogeneration unit with a SOFC stack can operate safely over a wide range of recirculation ratios without need for additional modifications. Ammonia-fueled units achieve electrical efficiency (55%) higher than hydrogen-based system (47.6%) but lower than installation fueled with natural gas (61.8%). • Anode off-gas recirculation in combined heat and power based on SOFC was studied. • Three fuels where considered: nautral gas, hydrogen and ammonia. • Wide range of recirculation can be achieved for all three fuels without modification. • Optimal recirculation ratio was found for each fuel and stack fuel utilization factor. • Highest electrical efficiency of up to 61.8% is achieved for natural gas fueled system. [ABSTRACT FROM AUTHOR]

The number of hydrogen refuelling stations worldwide has increased to over 700 due to the rapid development of green hydrogen energy. The risk assessment of hydrogen refuelling stations is indispensable to prevent accidents, and its foundation is accident scenarios screening. Although the integrated energy supply station containing fuels such as hydrogen, compressed natural gas (CNG), methanol eliminates the need for building hydrogen refuelling stations separately, the risk assessment for these complex systems has not been comprehensively studied. This paper proposes a scenario screening approach for identifying potential hazards in multi-fuel integrated energy supply stations. The risk of the processing unit was evaluated, and the leakage scenarios were pre-screened to identify credible leakage scenarios that adhere to the principle of maximum credibility by considering the frequency of occurrence and severity of consequences in two parts. Based upon acquired credible leakage scenarios, secondary screening of possible accident consequences was conducted by calculating the value of the credible factor to obtain the final maximum credible accident scenarios (MAS). Credible factors are derived from the accident probability, consequence severity, population density and asset density. By comparing the values of the credible factors, the accident scenarios with a low probability or low severity were eliminated, and the accident scenarios with the highest credible factors of each unit were retained as the MAS that require further consequence simulation analysis. The results offer a crucial foundation for the consequences and risk assessment of integrated energy supply stations. • Potential consequences of accidents caused by hydrogen and other fuel leaks. • Credible scenarios for fuel leaks are identified. • Maximum credible accident scenarios are determined. • Hydrogen compressor and associated piping are most susceptible to jet fires and explosions. [ABSTRACT FROM AUTHOR]

Photocatalytic hydrogen evolution using suitable photocatalysts in water is a sustainable way of energy production. In this paper, Ca2+ doped TiO 2 nano-sized polygon plates with oxygen vacancies were synthesized. The incorporation of Ca2+ induces the loss of oxygen and the formation of oxygen vacancies in the TiO 2 lattice, confirmed by XPS and EPR. TiO 2 with 0.040% Ca adding amount shows the best photocatalytic hydrogen production activity (4485 μmol g−1 h−1) with the apparent quantum efficiency of 46.4% at 370 nm, higher than undoped TiO 2 (2182 μmol g−1 h−1). The successful incorporation of Ca2+ and the formation of oxygen vacancies effectively inhibit the recombination of carriers in the reaction process and enhance the photocatalytic hydrogen production activity. • Ca2+ doped TiO 2 nano-sized polygon plates with oxygen vacancies were synthesized. • The incorporation of Ca2+ induces the formation of oxygen vacancies. • TiO 2 with 0.040% Ca shows the best photocatalytic H 2 production activity. • The incorporation of Ca2+ inhibits the recombination of electron-hole pairs. [ABSTRACT FROM AUTHOR]

The paper emphasizes the significance of sustainable energy solutions centered around electric vehicles (EVs). This involves Electric Intelligent Parking Lots (IPLs) that are interconnected with Renewable Energy Sources (RES) and Hydrogen Storage Systems (HSS) to achieve both technical and environmental goals. The study introduces a probabilistic approach to managing HSS-based energy in IPLs, employing the Probabilistic Two-Point Estimate Method (TPEM) to consider variables like sun radiation, temperature, wind speed, and IPL load. The Honey Badger Algorithm (HBA) is employed for optimization, striving to minimize operational costs related to energy distribution while maximizing profits by exploring revenue opportunities within the IPL system. This strategy enhances energy management and intelligent EV charging in IPLs, improving efficiency and economic viability. The approach is tested in a standard IPL environment integrated with RES and load demand, showcasing its successful technical and financial outcomes. Results reveal a 7.8 % profit increase from renewable resources and an additional 4.89 % when uncertainties are factored in. Ultimately, the proposed energy management framework utilizing HSS and RES integration proves effective in achieving objectives, with the potential for greater profitability through renewable resource incorporation and uncertainty consideration. • Optimal energy management framework proposed for electric vehicle integration in intelligent parking lots. • Simulation of efficient charging and discharging strategy in an IPL for electric vehicles. • Impact of renewable sources integration (wind and solar) on IPL efficiency and revenue generation. • Uncertainty analysis of renewable sources and load demands in IPL using two-point estimation method. • Smart integration of renewable sources, hydrogen storage, and electric vehicle charging for optimal operation of IPL. [ABSTRACT FROM AUTHOR]

The development of sustainable energy sources has become a major challenge for society. Green hydrogen, produced through the electrolysis of water using renewable energy sources, offers a potential solution to reducing our dependence on fossil fuels. The paper examines the integration of green hydrogen into various sectors, such as transportation, industry, power generation, and heating, highlighting its potential to decarbonize traditionally carbon-intensive areas. Furthermore, it analyses the strategies and policies employed by the European Union, Australia, Japan, the United States, and Canada to drive the development and adoption of green hydrogen technologies. The challenges and barriers that need to be addressed to fully realize the potential of green hydrogen, such as technological limitations, infrastructure development, costs and economic feasibility, regulatory and policy frameworks, and public perception and acceptance, have been investigated. Recommendations for overcoming these challenges and accelerating the adoption of green hydrogen technologies are provided, and the importance of research and development in this sector is emphasized. • Green hydrogen offers a sustainable solution to reduce fossil fuel dependency, decarbonizing key sectors. • Analyzed policies from the EU, Australia, Japan, the US, and Canada to foster green hydrogen technologies. • Discussing challenges: green hydrogen potential, tech limits, infrastructure, costs, regs, and public views. • Emphasized the importance of R&D and offers accelerating the adoption of green hydrogen technologies. [ABSTRACT FROM AUTHOR]

The All-electric ship (AES) concept has revolutionized the maritime sector. Indeed, AES is a promising solution for modern vessels where decreasing emission pollution, suppressing fossil fuel consumption, and making economical operation are its brilliant merits. Fuel cell (FC) technology based on clean hydrogen energy sources can play a significant role in meeting these requirements in the AES platform. Because of the slow transient response of the FC, an energy storage system (ESS) is required to improve AES performance in different operation scenarios. Therefore, optimal sizing of the FC and the ESS and proper design of energy management strategy is a challenging problem. This paper proposes a systematic approach for the optimal design of hybrid FC-ESS of AES power systems. The proposed method is based on an optimization technique to determine the optimal sizing of the FCs and the ESS. Capital investment, fuel consumption, personnel electrical safety, and occupied volume of the AES power system are the main objectives. The FC size, the battery size, the scheduled output power of the FC, and the battery are the decision variables. Genetic Algorithm (GA) is used to solve the optimization problem. To validate the numerical results, the optimization problem is also solved by Mayfly Algorithm (MA) separately. To assess the feasibility of the proposed strategy, the optimal design of hybrid FC-ESS for a vessel is implemented based on the proposed method. The simulation results validate the proposed approach's sufficiency to investigate and optimize the economic, safety, and dimensional aspects of designing the FC ship's IPS. Numerical results are reported for each design aspect. Considering the minor differences of the numerical results obtained by GA and MA, the optimum points are validated by the two techniques. Using the obtained results, various perceptions can be derived from the FC ship's IPS design. For example, the IPS cost in the cases with optimum volume, weight, and safety, has 2.3%, 2.6%, and 7.3% penalties, respectively compared to the case with the minimum cost. • Fuel cell-based electrification of a fishing ship based on practical information. • Systematic approach for optimal power system design of hydrogen-powered ship. • Proposing safety objective function for integrated power system of fuel cell ship. • Fuel cell hybrid IPS optimization based on volume, mass, cost and safety. • Estimation of propulsion power demand based on ship's resistance and speed profile. [ABSTRACT FROM AUTHOR]

Hydrogen is a type of clean secondary energy, and the hydrogen energy supply is vital to regional energy development. Guangdong is at the forefront of hydrogen energy deployment in China, and aims to achieve peak carbon by 2030. However, hydrogen production research is challenging due to complex technical routes, technical maturity levels, life-cycle carbon emissions, and costs. Multi-time-scale research is necessary to explore optimal production paths and their contributions to CO 2 emission reduction. This study discussed key technologies and the technical maturity of five hydrogen production routes: production from industrial byproducts and coal, wind, hydro-, and photovoltaic power. Policy scenarios were designed to investigate the potential of these routes and technology deployment intensity under medium- and long-term scenarios. This paper proposes a roadmap for hydrogen development and provides a reference for hydrogen production planning in Guangdong. This methodology can be applied in other regions for hydrogen energy development research. • Key technology maturity of the hydrogen production routes was evaluated. • Roadmap of hydrogen production in Guangdong Province was designed. • A method for research of hydrogen supply scenarios was proposed. [ABSTRACT FROM AUTHOR]

Hydrogen produced by water electrolysis using renewable energy is a sustainable alternative to steam reformation. As a nascent commercial technology, performance, and economic comparisons of anion exchange membrane water electrolyzers (AEMWE) to other electrolyzer technology benchmarks are not available. We present a techno-economic model estimating AEMWE's baseline levelized cost of hydrogen (LCOH) at $5.79/kg, considering trade-offs between current density, efficiency, stability, capital, and operating costs. The optimal current density is 1.38 A cm−2, balancing stability and performance for the lowest LCOH. Using low-cost electricity and larger stack sizes, AEMWE could achieve $2/kg low-carbon hydrogen. Technical improvements targeting system efficiency, particularly reducing overpotentials in hydrogen and oxygen evolution reactions, could further reduce LCOH to $1.29/kg, approaching U.S. Department of Energy cost targets. There are hopes this model could raise the profile of AEMWE's economic potential to produce green hydrogen and highlight its suitability for decarbonizing the energy sector. [Display omitted] • This paper examines the impact of current density on AEMWE performance and stability. • The model estimates the optimal current density with the lowest LCOH. • The model highlights areas of improvement with the greatest potential to reduce LCOH. • The results highlight recommendations for future directions in AEMWE research. [ABSTRACT FROM AUTHOR]

Hydrogen, as a clean energy source, has been widely used in the automotive industry. However, considering the difficulties of hydrogen storage and transportation, the in-situ production process has received increasing attention. In this paper, a hydrogen production system for dimethyl ether self-heating steam reforming is proposed, using a spiral tube reactor in which the oxidation of dimethyl ether occurs in the spiral tube, and the exothermic oxidation of dimethyl ether is used to provide heat for the dimethyl ether steam reforming hydrogen production reaction. A numerical model of the hydrogen production system for dimethyl ether self-heating reforming is developed, the model is simulated and analyzed, the accuracy of the model is verified through experiments, the influence of various parameters and on the system is analyzed, and the system is optimized. The results show that the proposed system can solve the problems of high energy consumption, low hydrogen yield and difficult reaction control faced by traditional autothermal reforming hydrogen production, and the system can achieve 87.79% dimethyl ether conversion rate, 84.94% hydrogen yield and 85.94% system thermal efficiency. [Display omitted] • Designed a self-heating hydrogen production reaction system for dimethyl ether reforming. • Derive the numerical model and control equation inside the reactor. • Effect of oxygen-to-ether ratio on reforming hydrogen production system is studied. • Effect of steam-to-ether Ratio on reforming hydrogen production system is studied. • Effect of reaction temperature on reforming hydrogen production system is studied. [ABSTRACT FROM AUTHOR]

Green hydrogen production from biomass is an eco-friendly and sustainable solution for reducing carbon emissions and promoting sustainable development. This paper presents potential green hydrogen production from available biomass resources, including agricultural crops and livestock waste in Kazakhstan in 14 regions. The study explores the potential of biomass-to-hydrogen production in Kazakhstan, including the availability and quality of biomass resources and environmental sustainability. The gasification process is chosen as the most efficient technology for biomass resource consumption to obtain green hydrogen. This is the first study in Kazakhstan contributes assessment of the geographic distribution of available biomass resources in the country. The total amount of green hydrogen production from agricultural waste is 432 tonnes/km2/year. Turkestan, Kyzylorda, Almaty, East Kazakhstan, Zhambyl, and North Kazakhstan are listed as regions with the highest green hydrogen production potential with an annual 122.2, 71, 57.6, 35.3, 29, and 28.5 tonnes/km2/year, respectively. Annual green hydrogen production from livestock waste is 5262 × 10−6 tonnes/km2/year which equals to 856 tonnes/year. The top three three regions with H 2 production are Turkestan, Almaty and East Kazakhstan regions with 208, 112.5, and 93 tonnes/year, respectively. The results provide a perspective contribution for different regions to the sustainable energy future and carbon neutrality in the country. • Estimation of H 2 production potential from biomass resources in Kazakhstan. • Gasification technology appears as the most promising alternative for H 2 production. • First study in Kazakhstan assesses the geographic distribution of available resources. [ABSTRACT FROM AUTHOR]

Biohydrogen production through photofermentation has gained significant attention as it provides a sustainable solution for clean energy supply and addresses wastewater concerns by utilizing volatile fatty acids (VFA) which are produced in dark fermentation. In this study, response surface methodology via a Face-centered Central Composite Design (FCCD) was employed to optimize buffer solution pH, ferric citrate concentration, sodium glutamate concentration to maximize biohydrogen production by Rhodobacter sp. MAY2 with mixed VFA (acetate, propionate, butyrate) as substrates. Results showed that the concentrations of ferric citrate, sodium glutamate, and buffer solution pH positively impact the biohydrogen production of Rhodobacter sp. MAY2. The optimal conditions were shown to be 0.36 mM ferric citrate, 11 mM sodium glutamate, and buffer solution of pH 7. The predicted hydrogen production potential (HPP) at these conditions (661.1 mL/L) was within 2 % of the actual HPP (647.7 mL/L). Kinetic parameters using the modified Gompertz equation showed that the predicted values for maximum potential cumulative H 2 production (P), maximum hydrogen production rate (R m), and lag time (λ) are comparable to those reported in literature. Overall, the study highlighted the potential of a local isolate, Rhodobacter sp. MAY2, for biohydrogen production and the suitable fermentation conditions for its growth. • Optimized pH, ferric citrate, and sodium glutamate enhanced Rhodobacter sp. MAY2 biohydrogen production. • Buffer pH, ferric citrate, and sodium glutamate significantly influenced biohydrogen yield. • Rhodobacter sp. MAY2 exhibited high substrate consumption efficiency for volatile fatty acids. [ABSTRACT FROM AUTHOR]