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This paper explores a novel method of focuses on utilizing ammonia as a hydrogen carrier that can be decomposed to produce hydrogen, the combustion of which produces steam for generating power in turbines. The simulation for such a process is performed on ASPEN Plus software. The key steps include compressing the ammonia and passing it through a fluidized bed reactor (FBR) for its decomposition, subsequently compressing the products before combusting the hydrogen with compressed air in a combustor and extracting power from the hot products through a series of turbines. The article examines in detail the effect of different parameters on the performance of the individual components as well as the overall process. Specifically, considerable emphasis is placed on the effects of varying pressures and temperatures on the functioning of the FBR at different catalyst loadings, their effects on the combustor performance and the dependence of the overall process on the air flowrate in the combustor. The comprehensive analysis elucidated on the energy efficiency of the process and it identified conditions at 2 bar pressure and 550 °C temperature as being the most favorable for ammonia decomposition and subsequent turbine power output while lean hydrogen combustion with excess air making the inlet hydrogen concentration less than 20% resulted in optimum temperatures at the turbine inlet. • The paper explores ammonia as a hydrogen carrier in the power plant industry through ASPEN PLUS process simulations. • The initial step is to decompose ammonia into nitrogen and hydrogen in a fluidized bed reactor, the optimum operating condition of which turns out to be 2 bar pressure and 550 °C. • The next steps involve mixing air with the decomposition products, pressurizing them to 40-60 bar, combusting hydrogen in a plug flow reactor to produce steam and finally expanding it in a series of turbines to generate power. • Detailed flow and more importantly, energy analysis of all the process units show ammonia as a very effective hydrogen carrier for applications in power plants. [ABSTRACT FROM AUTHOR]

This paper provides an in-depth examination of critical and strategic raw materials (CRMs) and their crucial role in the development of electrolyzer and fuel cell technologies within the hydrogen economy. It methodically analyses a range of electrolyzer technologies, including alkaline, proton-exchange membrane, solid-oxide, anion-exchange membrane, and proton-conducting ceramic systems. Each technology is examined for its specific CRM dependencies, operational characteristics, and the challenges associated with CRM availability and sustainability. The study further extends to hydrogen storage and separation technologies, focusing on the materials employed in high-pressure cylinders, metal hydrides, and hydrogen separation processes, and their CRM implications. A key aspect of this paper is its exploration of the supply and demand dynamics of CRMs, offering a comprehensive view that encompasses both the present sttate and future projections. The aim is to uncover potential supply risks, understand strategies, and identify potential bottlenecks for materials involved in electrolyzer and fuel cell technologies, addressing both current needs and future demands as well as supply. This approach is essential for the strategic planning and sustainable development of the hydrogen sector, emphasizing the importance of CRMs in achieving expanded electrolyzer capacity leading up to 2050. • Analyzes CRMs in hydrogen tech, focusing on electrolyzers and fuel cells. • Explores CRM implications in hydrogen storage and separation. • Investigates CRM supply and demand, identifying risks and strategies. • Highlights the role of CRMs in sustainable hydrogen sector development. [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]

Green hydrogen is crucial for society's access to peaceful, secure, and stable energy sources to flourish sustainably and get universal government support. To protect the environment and provide energy security, it is essential to use hydrogen as a sustainable fuel and energy source to cover the energy baseload. This paper investigates the developments of renewable energy (RE) and the potential for green hydrogen in the Middle East and North Africa (MENA) region. There is a considerable chance to use RE because of the MENA region's excellent solar radiation. On the other hand, many countries in the MENA region are classified as one of the poorest in water resources and are known to have water-energy challenges. This paper focuses on the water needed to produce hydrogen in countries with water scarcity. A strengths, weaknesses, opportunities, and threats (SWOT) analysis was performed for green hydrogen generation in the MENA, where recommendations for countries with a water-energy nexus can be made. Additionally, this paper offers suggestions for creating a sustainable hydrogen economy, such as cutting back on the domestic use of fossil fuels, subsidizing the renewable production industry, and supporting hydrogen manufacturing. • Green hydrogen production is highly affected by water scarcity. • SWOT analysis was performed on green hydrogen generation in the MENA. • Recommendations were provided on a country-by-country basis. [ABSTRACT FROM AUTHOR]

Green hydrogen can be the transitional solution required to reduce anthropogenic emissions and enhance energy independency from fossil fuel. To improve green hydrogen adoption, a cluster-based infrastructure, called a hydrogen hub, is devised taking into account the demand-supply interplay coupled with transport ease. In this paper, we have identified sites across states that are conducive for hydrogen hubs. It involves a multicriteria decision-making (MCDM) framework deployed to assign priorities within competing set of criteria. A comprehensive analytical hierarchy process (AHP) is used to rank criteria that are connected to establish a functioning hydrogen hub. These criteria include, but not limited to, proximity to refineries, fertilizer plants, substations, chlor-alkali units, steel manufacturing plants, water availability, access to gas pipelines, railway line access, and finally distance to highways. Our analyses indicate that proximity to refineries and fertilizers scored higher (scores directly proportional to importance) while railway line access scored the least. These prioritised scores are used to spatially locate sites using geographical information system. In a total of thirteen states identified, Gujarat had the largest parcel of most suitable land for setting up hydrogen hub followed by Maharashtra and Andhra Pradesh. For India to set up a functioning hydrogen economy and achieve green hydrogen goals, it is important to identify states that can drive the agenda forward. This paper illustrates a way (amongst many available ways) to identify states based on their strength and capability to fulfil the national goal of 5 million tons of green hydrogen by 2030. • The paper addresses setting up of green hydrogen hubs in India based on a multi-criteria site selection framework. • Nine selection criteria covering aspects of hydrogen ecosystem proposed to identify site(s) suitable for hydrogen hubs. • Integration of AHP and GIS is used to ascertain land parcels where hydrogen economy can sustain across states in India. • Zones in 13 states were identified as potential hydrogen hubs. [ABSTRACT FROM AUTHOR]

The current study examines a novel multigeneration plant that uses geothermal energy to produce clean and sustainable products. The process includes a re-compression supercritical Brayton power plant (re-sBC), an ejector cooling unit (EJCS), a humidifier dehumidifier desalination (HDH) unit, a Proton-Exchange Membrane (PEM) process, and a hot water preparation unit. The designed plant is able to generate hot water, cooling, power, hydrogen, and freshwater using the geothermal source. In the current paper, the thermodynamic analysis, CO 2 emission assessment, and exergoenvironmental index evaluation are executed to determine the system efficiency and the association between the system and the environment. A thorough parametric examination is fulfilled, to show how the system indicators impact efficiency and generated products. According to analysis data, the proposed multigeneration plant is able to generate 1278 kW of heating load, 229.6 kW of refrigeration capacity, and 109.5 kW of net power rate. Additionally, the capacity of the freshwater is 0.1188 kgs − 1 and the hydrogen is 0.001317 kgs − 1 . This developed system emits a total of 117 tonnes of CO 2 emissions per year for these useful outputs. In conclusion, the energetic and exergetic performance of the suggested MG plant are 14.09 % and 23.35 %, respectively. • A sustainable geothermal energy-based MG is proposed. • The thermodynamic, emission, and environmental analysis is conducted. • Design and evaluation of the Green hydrogen production and storage. • Re-compressed sBC integrated into geothermal driven MG plant. • Total energy and exergy efficiency is computed as 14.09 % and 23.35 %, respectively. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive techno-economic analysis of the world's first large-scale commercial Power-to-X (PtX) plant in Kassø, Denmark. This innovative facility combines solar photovoltaic (PV), an electrical grid, green hydrogen production, methanol synthesis, and district heating in an integrated system. We conduct an in-depth analysis to explore optimal operating conditions, the potential for sector coupling within the power and heat sectors, and the economic feasibility of the integrated system. In particular, we study different scenarios considering changes in solar PV power generation, electricity market price, CO 2 price, and methanol price to explore their impacts on the system performance. Our results show that the electrolyzer's operation, a pivotal component of the system, heavily depends on the electricity spot price as well as the methanol price. Based on the green production of methanol, a premium price of 4800 DKK/t (0.64 €/t) is considered in this study (selling price of 8400 DKK/t). The results show that in case of high electricity prices (2022 spot market) or no premium price for methanol, the optimum annual production of methanol decreases by 58% and 67%, respectively. Furthermore, we observe that the variability of solar power output significantly impacts the plant's performance and economic viability, as it supplies about 30% of the plant's power consumption. Although the results are unique to the Kassø plant, the study's techniques and insights can be applied to other comparable systems around the world. The study also highlights how crucial it is to take market, climate, and technical factors into account when developing and running integrated energy systems. • Techno-economic analysis of the world's first large-scale commercial Power-to-X (PtX) plant in Kassø, Denmark. • Insights to optimal operating conditions, sector coupling potential, and economic feasibility of Power-to-Methanol plants. • Analysis of the impact of market dynamics on the operational efficiency and economic viability of the integrated plant. • Study of the role of intermittent solar power and its impact on the performance and economic sustainability of the plant. [ABSTRACT FROM AUTHOR]

The production of green hydrogen through electrolysis, utilizing renewable energies, is recognized as a pivotal element in the pursuit of decarbonization. In order to attain cost competitiveness for green hydrogen, reasonable generation costs are imperative. To identify cost-effective import partners for Germany, given its limited green hydrogen production capabilities, this study undertakes an exhaustive techno-economic analysis to determine the potential Levelized Cost of Hydrogen in Germany, Norway, Spain, Algeria, Morocco, and Egypt for the year 2050, which represents a critical milestone in European decarbonization efforts. Employing a stochastic approach with Monte Carlo simulations, the paper marks a significant contribution for projecting future cost ranges, acknowledging the multitude of uncertainties inherent in related cost parameters and emphasizing the importance of randomness in these assessments. Country-specific Weighted Average Cost of Capital are calculated in order to create a refined understanding of political and economic influences on cost formation, rather than using a uniform value across all investigated nations. Key findings reveal that among the evaluated nations, PV-based hydrogen emerges as the most cost-efficient alternative in all countries except Norway, with Spain presenting the lowest Levelized Cost of Hydrogen at 1.66 €/kg to 3.12 €/kg, followed by Algeria (1.72 €/kg to 3.23 €/kg) and Morocco (1.73 €/kg to 3.28 €/kg). Consequently, for economically favorable import options, Germany is advised to prioritize PV-based hydrogen imports from these countries. Additionally, hydrogen derived from onshore wind in Norway (2.24 €/kg to 3.73 €/kg) offers a feasible import alternative. To ensure supply chain diversity and reduce dependency on a single source, a mixed import strategy is advisable. Despite having the lowest electricity cost, Egypt shows the highest Levelized Cost of Hydrogen, primarily due to a significant Weighted Average Cost of Capital. • LCOH projections for 2050 were determined through Monte Carlo Simulation. • PV-based hydrogen is the most cost-effective option in all countries except Norway. • Spain exhibits the lowest LCOH, followed by Algeria and Morocco. • Country-specific WACC variations significantly impact the LCOH. • Importing from Spain, Algeria, Morocco (PV), and Norway (onshore) is advised. [ABSTRACT FROM AUTHOR]

Power-to-Hydrogen (P2H) clean systems have been increasingly adopted for Virtual Power Plant (VPP) to drive system decarbonization. However, current models for the joint operation of VPP and P2H often disregard the full impact on grid operation or hydrogen supply to multiple consumers. This paper contributes with a VPP operating model considering a full Alternating Current Optimal Power Flow (AC OPF) while integrating different paths for the use of green hydrogen, such as supplying hydrogen to a Combined Heat and Power (CHP), industry and local hydrogen consumers. The proposed framework is tested using a 37-bus distribution grid and the results illustrate the benefits that a P2H plant can bring to the VPP in economic, grid operation and environmental terms. An important conclusion is that depending on the prices of the different hydrogen services, the P2H plant can increase the levels of self-sufficiency and security of supply of the VPP, decrease the operating costs, and integrate more renewables. • Design of a VPP operation model considering P2H systems. • Modeling and exploitation of multiple hydrogen consumption paths. • Integration of full AC OPF in the VPP network operating model. • Assessment of the impact of P2H systems in the VPP operation. • Analysis of P2H contribution to the VPP self-sufficiency and decarbonization goals. [ABSTRACT FROM AUTHOR]

Coupling water electrolyzers with solar and wind sources may be a promising solution in the near future for utilizing excess renewable energy. Indeed, many researchers have investigated various green hydrogen production systems, but a systematic approach should be developed to compare them. In addition, it is crucial to understand which solar and wind-based green hydrogen production systems have been studied and the literature gap on this topic. This review presents the latest research on green hydrogen production systems integrated with solar and wind technologies. One of the most significant novelties of this paper is to suggest a preliminary pathway and standardization strategy for the comparison of different green hydrogen production systems based on solar and wind sources. Various data and information are extracted from the most relevant papers in this field, such as renewable systems investigated, the location of the studied system, connection with the electrical grid, research type developed, final utilization of hydrogen considered, and performance indicators employed. This work will be an introductory guide for the community interested in green hydrogen production systems. • Comparison of solar and wind-based hydrogen production systems. • The combination of a water electrolyzer with solar and wind energy may be a promising solution. • More attention is needed on transient electrolyzer behaviour, battery degradation, and grid stability. [ABSTRACT FROM AUTHOR]

The production of energy, food, water, and other utensils by fossil fuels generates pollution that causes constant climate change. To minimize and avoid this phenomenon, opting for less polluting energy production sources is increasingly necessary. Green hydrogen (H 2), a renewable and clean fuel, is analyzed in bibliometric terms in the present work, emphasizing photosynthetic H 2. The data were obtained through the journal database list in Web of Science, in which a total of 1507 was published between January 2010 to September 2022, dealing with the production of photosynthetic green hydrogen. The country with the most significant publication is China, with respectively 24.50% of the publications, and the Chinese Academy of Sciences has 60 co-authored papers, the largest in co-authorship—most papers published in the international journal of hydrogen energy, with 19.49% of the publications. The raw materials identified as emerging are cyanobacteria and microalgae, Rhodobacter capsulatus , synechocystis sp pcc6803 and Chlamydomonas reinhardtii pointed out as the microalgae of most significant interest. However, it is necessary to improve them, given the decrease in inactivity provided by the Calvin-Benson cycle. Life cycle assessment studies are needed, as well as H 2 storage. There is a need to reduce the levelized cost of H 2 production, which is around 9.65–25.22 USD/gallon. Studies also point to using cyanobacteria and microalgae to produce other biofuels (bioethanol biodiesel) and materials (supercapacitors, batteries, and polymers). [Display omitted] • Evaluation of the photosynthetic production of green hydrogen. • Analysis of 1507 papers from the Web of Science with CiteSpace, Vosviwer and Exell. • Advanced bibliometric analysis of future trends in the production of green hydrogen. • Using photosynthetic methods to produce biofuels. • Polymer production uses carbon dioxide and green hydrogen. [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]

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 endeavors to utilize the numerical modeling method to evaluate the energy, economic, and environmental performances of a new hybrid PV-FC system for green hydrogen and electricity production. The proposed system consists of photovoltaic panels, fuel cells, an electrolyzer, a converter, and a hydrogen storage tank. A robust techno-enviro-economic (3E) analysis is conducted through comprehensive modeling for the system components using MATLAB/Simulink®. In this validated model, the essential parameters have been calculated: PV plant power, area and efficiency, electrolyzer efficiency, flow rate and power, stack power, area and efficiency, total LCOE of the integrated components, and CO 2 emission reduction. Moreover, the NSGA-II coupled with TOPSIS decision-making approach and Gaussian Process Regression machine learning method with selection kernel function are also utilized as a novel inclusion for the prediction and optimization of the 3E performances of this hybrid system. To obtain a multidimensional view of the optimization, six key decision variables of total stack power, fossil fuel-based generator energy, total CO 2 emissions coming from hydrogen production, total FC system voltage, module area, and number of PV modules have been adopted. The optimization problem encompasses maximizing the total fuel cell stack power and carbon emission reduction, while simultaneously minimizing the total stack area and levelized cost of energy. The simulation outcomes reveal that the stack can reach its maximum output power of 350 kW when operating temperatures are between 40 °C and 55 °C and there are more than 380 cells in the stack. Also, the LCOE was found to be less than $2/kWh for solar radiation above 250 W/m2 and PV outputs reaching 100 W. Further, Increasing FCs from 10 to 400 reduces CO 2 emissions by roughly 13% at 100 °C. Ultimately, the optimal configuration of the system yields stack power of 1589 kW, a total stack area of 269.9 m2, and total CO 2 emission reduction of 1268 ton CO2 , respectively. • Robust 3E analysis using MATLAB-based techno-environmental-economic study. • ML tool using GPR and GA optimization method used for performance optimization. • LCOE is less than $2/kWh for solar radiation above 250 W/m2 and 100 W PV output. • The PVFCEHST model exhibits a high degree of reliability and a robust integrated model. • FC power efficiency reaches 60% when operational temperature is between 40 and 55 °C. [ABSTRACT FROM AUTHOR]

Green hydrogen, produced from renewable electricity, can be transported long distances in multiple mediums. In this paper, a Techno-economic model is proposed to show the economic viability of global green hydrogen transport along 15 major regional routes such as Australia to Asia and Europe for the first time. A Monte Carlo-based technique is presented to assess the levelised cost of green hydrogen for different regions for the next 30 years. Depending on the specific route, green hydrogen can be transported in different forms, including ammonia, Liquid Organic Hydrogen Carrier (LOHC), Hydrogen Slush, compressed or liquefied hydrogen, etc. form and using different modes including shipping, truck, train, and pipeline. A linear programming analysis has been conducted for different regions, showing that among the global projected 300Mt of green hydrogen demand in 2050, 85% will need to be transported between regions to achieve the most economically optimal distribution. • Techno-economic analysis of green H 2 export via 15 worldwide regional trade routes. • Export model includes H2 generation, conversion, transport, and carbon prices. • In 2030, North America will be the largest exporter, followed by Australia. • Higher carbon prices allow for rapid growth in the green hydrogen industry. • Shipping is the most likely and cheapest H 2 export mode for distant transport. [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]

Hydrogen is not only an important energy carrier needed to achieve the global goal of carbon neutrality, but also an important way of international energy trade in the future. This research analyzes the advantages and challenges of China's participation in international hydrogen trade in detail, proposes the possible routes of China's international hydrogen trade, and proposes specific measures to enhance China's participation in international hydrogen trade. This paper proposes that China should take green hydrogen as its development direction, and guide the development of China's hydrogen trade with the principle of blue green cooperation and gray hydrogen withdrawal. In the future, China's hydrogen trade forms will be diversified, and the types of trade will cover the entire hydrogen energy industry chain. Therefore, China should accelerate the overall deployment of hydrogen trade and the construction of hydrogen trade infrastructure, and build a more sophisticated hydrogen economy. [Display omitted] • The advantages of China's international hydrogen trade are analyzed. • Discussed China's possible international hydrogen trade routes in the future. • The obstacles affecting China's hydrogen competitiveness are analyzed. • Put forward suggestions to promote China's international hydrogen trade. [ABSTRACT FROM AUTHOR]

This paper explores the use of Solar Chimney Power Plants (SCPPs) for the production of green hydrogen as a means to store excess electrical energy generated from renewable energy resources (RESs). The proposed structure produces electrical energy and distilled water by heating the air under the SCPP. The electrolyzer is integrated into the seawater pool and installed at the solar chimney's base. The weather conditions at the proposed location of the SCPP including solar radiation, temperature, humidity, and wind speed, are analyzed to assess their impact on the performance of the SCPP. The potential applications and economic feasibility of the SCPP are discussed, considering its contribution to renewable energy generation and the benefits of hydrogen as a clean energy carrier. The results show that solar radiation levels and favorable temperature profiles play an important role in the performance of the SCPP. The SCPP could produce 380,263 kW h of electrical energy and 139,443 tons of distilled water annually. The results also showed that the SCPP could produce 13,000 kg of green hydrogen and 173,224 kg of oxygen annually. The revenue generated from the production of H 2 and O 2 has improved the levelized cost of energy (LCOE) for the SCPP to 0.51 $/kWh and made it compete with other energy production facilities. Monthly variations in electrical energy, H 2 , O 2 , and distilled water production, highlight the dependence of hydrogen production on solar intensity and temperature. Overall, the research demonstrates the potential of SCPPs and hydrogen production as a sustainable and efficient solution for storing and utilizing excess renewable energy. [Display omitted] • Solar-electrolysis system combing solar chimney & electrolysis station is proposed. • The system produces green hydrogen, oxygen, desalinated water, and electricity. • The solar-electrolysis system was modeled using MATLAB mathematical modeling. • The system produced 380 MW h, 13 ton H 2 , 173.3 ton O 2 , and 139,443 ton water per year. [ABSTRACT FROM AUTHOR]

Considering the abundance of renewable energy potential in Turkey, green hydrogen derived from renewable sources holds great promise as a fuel. This paper presents a model for obtaining green hydrogen from medium-temperature geothermal sources. In this model, the Zilan location in the Van province of Turkey was identified as a suitable site for electricity and hydrogen production from low or medium-temperature geothermal sources due to its significant geothermal and water resource potential. In this regard, the installed capacity of the Organic Rankine Cycle (ORC) geothermal power plant is determined by using Monte Carlo Simulation based on the characteristics of the geothermal well at this location, and subsequently, the hydrogen production performance has been evaluated by analyzing the water of Lake Van. According to the analysis results, Lake Van was found to be efficient for hydrogen production. Hydrogen production from Lake Van water was subsequently simulated using the electrolysis method with this ORC geothermal power plant. According to the findings of this model, the hourly hydrogen production potential at this location using a 1.4 MW ORC plant, based on 2022 data, was estimated to be 18.6 kg, which is projected to increase to 28 kg based on 2050 estimated data. In addition, the techno-economic analysis of this compact green hydrogen production process was conducted in the study. The production cost of 1 kg of hydrogen was calculated to be €4.91 in 2022, while it is expected to be €1.21 in 2050. These results indicate that ORC technology will become competitive in hydrogen production in the upcoming years. • Determining the installed capacity of an ORC plant using Monte Carlo simulation. • Producing green hydrogen through an ORC power plant. • Analysis of the hydrogen production potential of the relevant water source. • Selection of the suitable electrolysis unit. • Hourly hydrogen production capacity of compact facility. [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]

This paper presents a new approach to calculating the levelized cost of hydrogen (LCOH) using a stochastic model under an uncertainty and risk perspective. The research problem is associated with how to integrate the concept of financial risk to assess investments in small-scale green hydrogen production for more robust results, resolving issues related to underlying economic and technical factors, often overlooked, that may impact the production of green hydrogen in Brazil and Germany. The approach is applied to an investment project at two localities: Itajubá, Brazil, and Cologne, Germany, to investigate the underlying economic and technical factors that may impact the production of green hydrogen. In this stochastic approach, the Value at Risk (VaR) is calculated with a confidence level of 95% for 5000 LCOH values for each city, generated by the Monte Carlo Simulation (MCS). MCS results show that a correlation between assumptions (uncertainties) significantly affects LCOH with more favorable conditions to produce green hydrogen in Cologne. The risk analysis results show a significant difference concerning the deterministic approach when implementing the risk measure with VaR-LCOH of US$8.39 for Itajubá and VaR-LCOH of US$8.21 for Cologne. • Green hydrogen Investments are evaluated techno-economically in Brazil and Germany. • A Monte Carlo approach under uncertainty and risk conditions is implemented. • A stochastic LCOH based on VaR-LCOH metric is proposed to evaluate the risk. • The different nuances that the assumptions assume in calculating LCOH are discussed. • The risk analysis shows a difference regarding the deterministic approach. [ABSTRACT FROM AUTHOR]

Green Hydrogen (GH) is increasingly recognized as a viable solution in the United States (US) for meeting energy demands, achieving net zero emissions by 2050, and mitigating the intermittent nature of renewable sources such as wind and solar. This review paper identifies and examines three crucial research areas concerning GH. Despite significant federal, state, and business investment in the development of hydrogen technology, numerous questions have remained unanswered including economic viability, social acceptance, and policies and regulations. In comparison to the US, Europe, and Asia have taken a lead role in studying the social and regulatory aspects of GH. The study shows limited focus on social acceptance, and the absence of dedicated policies and regulations for hydrogen. The US lacks coordinated policies for GH and is blended with natural gas. The literature shows that the relationship between economics, social sciences, and policies and regulations are intrinsic. The success of GH in the US will require massive investments, public and private collaboration, research on social sciences, and regulatory support. Hence, the GH rollout will bridge the energy transition, and climate and development targets which guide future industrial, government and public decisions. • Knowledge and experience play a major role in the acceptance of green hydrogen. • Green hydrogen technology lacks a value chain. • Lack of green hydrogen-specific regulatory agencies and standards in the US. • Economic, social, and regulatory challenges interlinked for green hydrogen. [ABSTRACT FROM AUTHOR]

In this paper, a novel stochastic risk-averse mixed-integer linear programming (MILP) model is developed for optimal electricity procurement of hydrogen fuel stations (HFSs) with responsive hydrogen demands. In the developed model, HFS operator may procure its required electricity through day-ahead (DA) market, bilateral contracts, a contract with withdrawal penalty (CWP) and balancing market. The HFS is committed to inject a pre-specified volume of hydrogen into a natural gas network. In the developed stochastic model, the uncertainties in hydrogen demand and DA market prices are characterized as random variables and modeled as scenarios. The developed model is a two-stage model in which the decisions on transactions with bilateral contracts are the first-stage decision variables and the other decision variables belong to the second stage. The risk of suffering from high procurement costs is modeled using the Conditional Value at Risk (CVaR). The results confirm the efficiency of the proposed model both in terms of reduction in HFS expected cost and risk alleviation. The results show that the transaction through bilateral contracts decreases the expected cost and CVaR respectively by 6% and 3%. The results also indicate that the participation in the balancing market decreases the expected cost and CVaR respectively by 6% and 1.6%. As per results, in scenarios in which DA market prices are lower than CWP prices, HFS operator prefers to pay a penalty fee and withdraw from CWP. The sensitivity of HFS profit to the weight factor of risk metric and the participation factor of responsive demands are assessed. [Display omitted] • A model is developed for electricity procurement of hydrogen fuel stations (HFSs). • The uncertainties in demands and market prices are considered. • HFS procures electricity by day-ahead and balancing market and bilateral contracts. • Impact of different markets and transactions on HFS profit is assessed. • Sensitivity of HFS profit to weight of risk metric is assessed. [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]

The hybrid thermochemical copper-chlorine (Cu–Cl) cycle for water splitting, developed as a novel approach to produce green hydrogen, has gained greater attention. A series of close-loop reactions makes the process environmentally friendly. A newly developed hybrid six-step Cu–Cl cycle consists of thermochemical, electrochemical, and a unit operation of spray drying. The present paper analyzes the configuration of the six-step Cu–Cl cycle thermodynamically. Studies on many factors are carried out to determine the cycle's total energy and exergy efficiency. The modeling and simulation of the six-step process was done by Aspen Plus. The six-step cycle was found to have an energy and exergy efficiency of 38.94 % and 52.74 %, respectively. The effect on exergetic efficiency with ambient temperature and cycle temperature variation was also investigated. The enhancement in the effectiveness of six steps Cu–Cl cycle could be possible from the current study analysis using thermal recovery and minimizing exergy destructions. [Display omitted] • Thermodynamic evaluation of novel ICT-OEC copper-chlorine thermochemical cycle. • An investigation based on mass, energy, and exergy balances. • The energy and exergy efficiency of the overall system is 38.94 % and 52.74%, respectively. • The hydrogen production rate of the system is 0.002 kg/s. [ABSTRACT FROM AUTHOR]