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This paper examines the potential of solar and hydrogen (H 2) energy-based hybrid energy systems for residential applications. The growing need for energy and the demand for sustainable energy sources have led to the development of integrated energy systems that combine renewable energy resources to meet energy needs. This paper overviews recent studies on hybrid energy systems for on-grid and off-grid residential utilizations. It discusses the system configuration and components of hybrid energy systems, including solar panels, electrolyzers, fuel cells (FC), and batteries. It also covers the technical optimization of integrated energy systems, including sizing, control strategies, and economic analysis. The key findings of this review paper indicate that hybrid energy systems can offer dependable and sustainable energy for residential applications. Through numerical analyses, the optimal dimensioning of the system elements and control strategies can significantly enhance the system's performance and lower the cost of energy. This study also highlights the challenges and opportunities for integrating hybrid energy systems within residential applications. Overall, it provides in-depth perspectives on the possibilities inherent in solar and hydrogen energy-based hybrid energy systems for residential applications. The findings can guide future research and the advancement of hybrid energy systems for sustainable energy solutions. • Comprehensive review on solar and hydrogen-based residential applications. • Holistic approach to system configuration, optimization, and economics. • Detailed analysis of interconnected components enhancing system efficiency. • Unique focus on real-world residential applications and scenarios. • Broad applicability across diverse geographical regions. [ABSTRACT FROM AUTHOR]

To tackle the carbon emission problem, the exploitation of renewable energy resources (RESs) with zero emissions has gained much importance. In this context, hydrogen has become an important resource to involve itself in distributed energy resources (DERs) to generate electricity, energize vehicles, and heat our living areas. The utilization of hydrogen technologies is indispensable due to their procurement, environmental friendliness, and high efficiency for DERs. A challenging area in the field of hydrogen energy technologies is extracting efficient power and integration to DERs. This paper investigates how to model and operate a proton exchange membrane fuel cell (PEMFC) stack in a DER application to establish a living lab facility for educational and research purposes by covering Power-to-X (P2X). The PEMFC model of the studied system is designed in a MATLAB/Simulink environment and implemented in an experimental testbed. Thus, a fuel cell (FC) unit as a complementary source is preferred to be used near a photovoltaic (PV) array, a small-scale wind turbine (WT), and a lead acid battery energy storage system (BESS) by creating a P2X concept to form a living lab platform. Beyond the model, regarding the experimental part, a PV array, a WT, and a BESS are combined with a PEMFC module that is rated output of 1200 W. Expect for all systems, the FC part is emphasized in this study. Also, a dynamic model of the mentioned PEMFC is proposed and verified. • Importance of hydrogen energy is focused on its advantages, future role, potential, and challenges. • FC unit as a complementary source is evaluated by creating a P2X concept. • This platform is designed to meet the energy needs of research-education, diversify the supply, increase energy independence. • Energy procurement is supplied via green energy during a lesson, which is noteworthy and instructive. • Feasibility of combined PV/WT/BESS/PEMFC system is investigated. [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]

The authors have developed an autonomous hydrogen energy complex and analyzed its economic efficiency. The developed energy complex is multifunctional. The main result of the work is the production and supply of electricity to the power system during hours of increased load. In addition, the low-power steam turbines included in the energy complex can provide plant-wide backup of the NPP's own needs in the event of a station blackout: based on the experimental data of the Balakovo NPP, it was previously shown that one power unit with a low-power turbine using the energy of the residual heat from the reactor can for a long time to provide electricity to required power units. Thanks to the installation of low-power turbines as part of the hydrogen energy complex, their constant warm state and self-sufficiency will be ensured by generating electricity for the power grid or for own needs in the normal mode. The paper considers options for installing an autonomous hydrogen power complex with and without replacing expensive external heat exchangers of the system for passive removal of heat from the reactor core. The efficiency of an alternative option without installing a storage system with the sale of off-peak electricity to the power system, which, in the option with AHC, is used to generate hydrogen/oxygen by electrolysis, depending on the tariff for off-peak electricity, is also calculated. Due to the lack of existing analogues of the hydrogen energy complex, several options for the proposed investment were considered. The results of the study revealed that the replacement of expensive equipment of the passive heat removal system significantly increases the economic efficiency of the proposed redundancy system. For the accepted options for capital investments, the boundary values of the off-peak selling tariff for electricity are shown, at which the use of the storage system is more efficient in comparison with the sale of nightly electricity to the power system. [ABSTRACT FROM AUTHOR]

This paper focuses on the design and use of a control system for a renewable energy production plant based on hydrogen. The proposed control system aims at ensuring the stability and smooth functionality of the plant, which consists of a (i) photovoltaic system connected to an electrolyzer through a battery, (ii) a DC/DC step down transformer, and (iii) an electrolyzer heat exchange system. In this study, solar irradiance is the main system input, and hydrogen production the main output. Since the system utilizes solar energy as input, it depends on the random input of solar irradiance, ambient temperature, and wind flow. Furthermore, the electrolyzer's functionality is subject to several operational variables including cell voltage, current, temperature, and pressure. The electrolyzer heat exchange system operates at specified water temperatures and flow rates. The DC/DC output voltage, and therefore the voltage supplied to the electrolyzer, is regulated by changing its duty cycle. To regulate hydrogen production in the renewable energy production plant, an efficient control system is required. Accordingly, in this work, a control system is designed accounting for three different electrolyzer technologies, alkaline, PEM (proton exchange membrane), and E-TAC (electrochemical - thermally activated chemical water splitting). Subsequently, the effectiveness of the control system is analyzed using Matlab and Simulink models. The main results indicate that the battery is a crucial element in the whole system as it supplies the necessary energy to the electrolyzer. By regulating the appropriate components, the proposed control system proved capable of minimizing power fluctuations and increasing system efficiency up to 20% depending on ambient conditions. Additionally, the results indicate E-TAC and PEM efficiencies 13% and 7% higher than alkaline, respectively. [Display omitted] • Design of a control system for three different electrolyzer technologies. • Use of control systems for electrolyzer voltage and heat exchange. • Photovoltaic system connected to an electrolytic one through a battery. • Proposed control system increases system efficiency up to 20%. [ABSTRACT FROM AUTHOR]

This paper presents a novel energy management strategy (EMS) to control a wind-hydrogen microgrid which includes a wind turbine paired with a hydrogen-based energy storage system (HESS), i.e., hydrogen production, storage and re-electrification facilities, and a local load. This complies with the mini-grid use case as per the IEA-HIA Task 24 Final Report, where three different use cases and configurations of wind farms paired with HESS are proposed in order to promote the integration of wind energy into the grid. Hydrogen production surpluses by wind generation are stored and used to provide a demand-side management solution for energy supply to the local and contractual loads, both in the grid-islanded and connected modes, with corresponding different control objectives. The EMS is based on a hierarchical model predictive control (MPC) in which long-term and short-term operations are addressed. The long-term operations are managed by a high-level MPC, in which power production by wind generation and load demand forecasts are considered in combination with day-ahead market participation. Accordingly, the hydrogen production and re-electrification are scheduled so as to jointly track the load demand, maximize the revenue through electricity market participation and minimize the HESS operating costs. Instead, the management of the short-term operations is entrusted to a low-level MPC, which compensates for any deviations of the actual conditions from the forecasts and refines the power production so as to address the real-time market participation and the short time-scale equipment dynamics and constraints. Both levels also take into account operation requirements and devices' operating ranges through appropriate constraints. The mathematical modeling relies on the mixed-logic dynamic (MLD) framework so that the various logic states and corresponding continuous dynamics of the HESS are considered. This results in a mixed-integer linear program which is solved numerically. The effectiveness of the controller is analyzed by simulations which are carried out using wind forecasts and spot prices of a wind farm in center-south of Italy. • Design of control algorithms for islanded and grid-connected microgrids. • Development of hierarchical MPCs to target long-term and short-term operations. • Tracking the load demand and maximizing the revenue via electricity markets. • Minimization of the HESS operational costs. [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]

In this paper, wind resource availability was determined by analyzing the meteorological wind energy potential at the hub height of wind turbines. The wind resource potential was identified in specific geographic locations. Technical factors, such as siting requirements and resource availability, were taken into account in the investigation. The economic potential was calculated for each area of Algeria, considering overall losses. Subsequently, the potential for reducing fossil fuel usage was determined through wind to hydrogen estimation. The main components utilized in this work were a Vestas-90 wind turbine (V90–2.0 MW) and an alkaline electrolyzer. The analysis employed a Geographical Information System (GIS) tool. The results demonstrate Algeria's significant potential for wind to hydrogen production, estimated at 1.093 Gt/year without constraints, and reduced to 1.066 Gt/year when considering constraints. The levelized cost of wind to hydrogen production in Algeria varies between 1.51 and 15.37 US $/kg, depending on the chosen wind turbine. The wind to hydrogen production potential identified has the capacity to replace the entire current fossil fuel consumption in the transportation sector, which amounts to 5.28 Mt H 2 /year. The utilization of wind to hydrogen in the transport sector results in a significant reduction of CO 2 emissions, with a calculated avoidance of 45.69 Mt compared to the use of gasoline and diesel. Hydrogen produced from wind energy resources also could be used to support other sectors, including residential, agricultural, and industry in Algeria. • GIS-Based approach is used to evaluate the potential for wind to hydrogen production in Algeria. • The total wind to hydrogen potential in Algeria, when considering constraints, is estimated at 1.066 Gt/year, covering an area of 730,719 km2. • The levelized cost of wind to hydrogen production in Algeria ranges between 1.51 and 15.37 US $/kg, depending on the selected wind turbine (V90–2.0 MW). • The CO 2 emissions avoided in the transport sector are 45.69 Mt compared if the same amount of gasoline and diesel used. [ABSTRACT FROM AUTHOR]

Clean energy resources will be used more for sustainability improvement and durable development. Efficient technologies of energy production, storage, and usage results in reduction of gas emissions and improvement of the world economy. Despite 30% of electricity being produced from wind energy, the connection of wind farms to medium and large-scale grid power systems is still leading to instability and intermittency problems. Therefore, the conversion of electrical energy generated from wind parks into green hydrogen consists of an exciting solution for advancing the development of green hydrogen production, and the clean transportation sector. This paper presents a techno-economic optimization of hydrogen production for refueling fuel cell vehicles, using wind energy resources. The paper analyses three configurations, standalone Wind-Park Hydrogen Refueling Station (WP-HRS) with backup batteries, WP-HRS with backup fuel cells, and grid-connected WP-HRS. The analysis of different configurations is based on the wind potential at the site, costs of different equipment, and hydrogen load. Therefore, the study aims to find the optimized capacity of wind turbines, electrolyzers, power converters, and storage tanks. The optimization results show that the WP-HRS connected to the grid has the lowest Present Worth Cost (PWC) of 6,500,000 €. Moreover, the Levelized Hydrogen Cost (LHC) of this solution was found to be 6.24 €/kg. This renewable energy system produces 80,000 kg of green hydrogen yearly. • Wind to green hydrogen represents an interesting solution for greenhouse gas reduction. • Three configurations of wind-park stations designed for green hydrogen production are analyzed. • Grid-connected wind park consists of an optimal solution for the wind park hydrogen station. • The Levelized cost of hydrogen production using a 5 MW grid-connected wind park is 6.24 €/kg. [ABSTRACT FROM AUTHOR]

Developing a thriving hydrogen industry will depend on public and community support. Past research, mainly focusing on the acceptance of hydrogen fuelling stations and cars, suggests that people generally support hydrogen energy technology (HET). Few studies have, however, considered how people think about other components of the hydrogen supply chain (i.e., technologies required to make, store, transport and use hydrogen). Moreover, there has been limited research investigating how people interpret and develop beliefs about HET after being presented with technical information. This paper attempts to address these research gaps by presenting the findings from four face-to-face focus group discussions conducted in Australia. The findings suggest that people have differing views about HET, which depends on the type of technology, and these views influence levels of support. The study also revealed concerns about a range of other factors that have yet to be considered in hydrogen acceptance research (e.g., perceived water use, efficiency and indirect benefits). The findings highlight the value of qualitative research for identifying salient beliefs that shape attitudes towards HET and provide recommendations for future research and how to effectively communicate with the public and communities about an emerging hydrogen industry. • Focus group discussions with Australians about whole hydrogen supply chain. • Generally positive, but tentative, attitudes toward hydrogen overall. • Stronger support for industrial applications over domestic/household applications. • Concerns raised about hydrogen's efficiency and its conflict with other technologies. • Support for more research and pilot projects to provide tangible evidence. [ABSTRACT FROM AUTHOR]

This paper presents a study that focuses on alleviating the impacts of grid outages in Ethiopia. To deal with grid outages, most industrial customers utilize backup diesel generators (DG) which are environmentally unfriendly and economically not viable. Grid-integration of hybrid renewable energy systems (HRES) might be a possible solution to enhance grid reliability and reduce environmental and economic impacts of utilizing DG. In this study, an optimization of grid integrated HRES is carried out for different dispatch and control strategies. The optimal power supply option is determined by performing comparative analysis of the different configurations of grid integrated HRES. The result of the study shows that grid integrated HRES consisting of photovoltaic and wind turbine as renewable energy sources, and battery and hydrogen as hybrid energy storage systems is found to be the optimal system to supply the load demand. From the hydrogen produced on-site, the FC generator and FCEVs consume 143 620 kg/yr of hydrogen which is equivalent to 394 955 kg/yr gasoline fuel consumption. This corresponds to saving 1 184 865 kg/yr of CO 2 emissions and 605 703 $/yr revenue. Besides, this system yields 547 035.4 $/yr revenue by injecting excess electricity to the grid. The study clearly shows the economic and environmental viability of this new technology for implementation. • Modeling and optimization of grid-integrated HRES including grid-reliability and dispatch control. • Storage of excess electricity produced from renewable energy sources in batteries. • Onsite production of renewable hydrogen with excess electricity produced from renewable energy sources. • The role of renewable hydrogen for simultaneous decarbonization of electricity and transportation sectors. • Minimizing overall operating costs by injecting excess electricity to the grid. [ABSTRACT FROM AUTHOR]

Establishing an industrial park-integrated energy system (IN-IES) is an effective way to reduce carbon emission, reduce energy supply cost and improve system flexibility. However, the modeling of hydrogen storage in traditional IN-IES is relatively rough. In order to solve this problem, an IN-IES with hydrogen energy industry chain (HEIC) is proposed in this paper. Hydrogen production, transportation, and storage technologies are applied in HEIC. Firstly, a novel long-term hydrogen storage model considering different time steps is presented. Secondly, hydrogen compressor models considering different pressure ratios are further employed. On this basis, the impact of the HEIC on the planning and operation results of IN-IES is studied. Finally, the superiority and the effectiveness of the proposed model and planning method are verified by simulation cases. • The hydrogen energy industry chain including hydrogen production, storage, and transportation technologies. • A novel long-term hydrogen storage model is proposed that considers different time steps. • Different hydrogen compression levels are utilized to hydrogen compressor models. [ABSTRACT FROM AUTHOR]

Population growth and the expansion of industries have increased energy demand and the use of fossil fuels as an energy source, resulting in release of greenhouse gases (GHG) and increased air pollution. Countries are therefore looking for alternatives to fossil fuels for energy generation. Using hydrogen as an energy carrier is one of the most promising alternatives to replace fossil fuels in electricity generation. It is therefore essential to know how hydrogen is produced. Hydrogen can be produced by splitting the water molecules in an electrolyser, using the abondand water resources, which are covering around ⅔ of the Earth's surface. Electrolysers, however, require high-quality water, with conductivity in the range of 0.1–1 μS/cm. In January 2018, there were 184 offshore oil and gas rigs in the North Sea which may be excellent sites for hydrogen production from seawater. The hydrogen production process reported in this paper is based on a proton exchange membrane (PEM) electrolyser with an input flow rate of 300 L/h. A financially optimal system for producing demineralized water from seawater, with conductivity in the range of 0.1–1 μS/cm as the input for electrolyser, by WAVE (Water Application Value Engine) design software was studied. The costs of producing hydrogen using the optimised system was calculated to be US$3.51/kg H 2. The best option for low-cost power generation, using renewable resources such as photovoltaic (PV) devices, wind turbines, as well as electricity from the grid was assessed, considering the location of the case considered. All calculations were based on assumption of existing cable from the grid to the offshore, meaning that the cost of cables and distribution infrastructure were not considered. Models were created using HOMER Pro (Hybrid Optimisation of Multiple Energy Resources) software to optimise the microgrids and the distributed energy resources, under the assumption of a nominal discount rate, inflation rate, project lifetime, and CO 2 tax in Norway. Eight different scenarios were examined using HOMER Pro, and the main findings being as follows: The cost of producing water with quality required by the electrolyser is low, compared with the cost of electricity for operation of the electrolyser, and therefore has little effect on the total cost of hydrogen production (less than 1%). The optimal solution was shown to be electricity from the grid, which has the lowest levelised cost of energy (LCOE) of the options considered. The hydrogen production cost using electricity from the grid was about US$ 5/kg H 2. Grid based electricity resulted in the lowest hydrogen production cost, even when costs for CO 2 emissions in Norway, that will start to apply in 2025 was considered, being approximately US$7.7/kg H 2. From economical point of view, wind energy was found to be a more economical than solar. • Overview of hydrogen production technologies. • Assessment of cost of desalination processes in relation to the total hydrogen production costs. • Investigation of applicability of offshore hydrogen production from seawater. • To assess the green hydrogen production potential offshore. [ABSTRACT FROM AUTHOR]

The shortage of fossil energy has become a growing global concern. It is particularly important to make full use of the infinite solar energy resources, and transform them into sustainable and clean energy. The development of hydrogen energy has become a feasible solution to solve the energy shortage problem. The preparation of photocatalysts featuring efficient charge transfer channels and high hydrogen production activity provides a pathway for the development of hydrogen energy. In this paper, we report for the first time the direct assembly of 2D ZnIn 2 S 4 (ZIS) nanosheets on the surface of CoTiO 3 (CTO). The synthesized CoTiO 3 /ZnIn 2 S 4 (CTO/ZIS) photocatalyst features a direct Z-scheme charge transfer channel, which enhances the separation rate of photogenerated carriers, and accelerates the photocatalytic H 2 evolution (PHE) rate. Without the assistance of any co-catalyst, the PHE rate of prepared CoTiO 3 /ZnIn 2 S 4 was as high as 5.21 mmol g−1 h−1. Moreover, the H 2 evolution rate of CoTiO 3 /ZnIn 2 S 4 almost did not decrease significantly after four consecutive 4 h cycles. This investigation provides a valuable approach for the exploitation of novel and efficient Z-scheme photocatalysts in the application of solar energy to hydrogen energy conversion. Using the Z-scheme CoTiO 3 /ZnIn 2 S 4 photocatalyst, water is decomposed under visible light irradiation to produce large amounts of H 2. The conversion of solar energy to hydrogen energy is realized. [Display omitted] • This is the first report of in situ assembly of ZnIn 2 S 4 nanosheets on CoTiO 3 surface. • The as-prepared CoTiO 3 /ZnIn 2 S 4 showed a new Z-scheme heterojunction. • The CoTiO 3 /ZnIn 2 S 4 heterojunction displayed an improved photocatalytic hydrogen evolution rate. [ABSTRACT FROM AUTHOR]

Nowadays the trend of increasing the generation units based on renewable energy sources in the electric power system can be observed. Obviously, this is due to the intensifying level of consumer load and demand for electricity. However, renewable generation is characterized by intermittent energy production, which can cause and potential imbalance between generation and demand, especially during off-peak periods. Therefore, in order to ensure a reliable power supply to consumers, it is necessary to use a maneuverable reserve of capacity, such as energy storage systems, in conjunction with the renewable energy source unit. Over the past 10 years, the energy storage market has grown by almost 50%: the installed capacity of energy storage system in the world is about 5 GW. Analysis of the literature on the subject determines the need to study the impact of these devices on the parameters of electric power systems and one of the primary tasks is to determine the optimal location and capacity of energy storage system in the power system. This paper presents the result of solving the task of determining the optimal parameters of a hydrogen energy storage system using the particle swarm optimization method for example a test scheme radial distribution system – 33 bus IEEE. The choice of the type of energy storage is based on such advantages of a hydrogen energy storage system as environmental friendliness, high energy capacity and the ability to store electricity for a long period of time. In addition, compared to lithium-ion batteries, hydrogen energy storage systems have a long life time of about 25 years, during this period of time there is no degradation and significant deterioration of its properties. All these advantages of hydrogen as an energy carrier allow to take into account not only the criterion of total value of active power losses and its maximum reduction respectively, but the possibility and economic efficiency of partial use of the stored hydrogen for other needs when determining the optimal scenario of their operation in the process of discharge. [ABSTRACT FROM AUTHOR]

Nowadays, the scheme of a stand-alone microgrid utilizing renewable energy is regarded as an effective approach to guarantee the power supply of an off-grid system. However, the intermittent nature of renewables brings new challenges to the determination of the optimal operation point for a hybrid energy system (HES). To address this issue, this paper proposes a subsection bi-objective optimization dynamic programming strategy for the HES consisting of photovoltaic, fuel cell, electrolyzer, hydrogen storage system, and battery bank. Within the proposed strategy, reasonable rule-based judgment is introduced to reduce the complexity of system control. Moreover, dynamic programming is selected to obtain the global optimal power distribution scheme. Meanwhile, a multi-objective genetic algorithm strategy is designed for comparative analysis. The results in two typical cases indicate the proposed strategy can improve photovoltaic utilization by 0.95% and 0.0003%, and fuel economy by nearly 50%. [Display omitted] • The hybrid energy system is modeled to clarify the operation mechanism. • Subsection bi-objective optimization dynamic programming is proposed. • Rule-based judgment is introduced to reduce the complexity of the optimization. • Two-staged optimization is implemented to improve fuel economy and utilization. [ABSTRACT FROM AUTHOR]

Microalgae originating from wastewater has been exhibiting particularly promising results in terms of biohydrogen production and wastewater treatment. This paper aims to review the factors affecting production, pretreatment techniques to improve synthesis, advanced technologies utilized for enhancing biohydrogen production, and techno-economic feasibility evaluation of the processes at a commercial scale. Microalgae possess metabolic components to synthesize biohydrogen using photobiological and fermentative processes but must undergo pretreatment for efficient biohydrogen production. The efficiency of these processes is influenced by factors such as the microalgae species, light intensity, cell density, pH, temperature, substrates, and the type of bioreactors. Moreover, many limitations, such as oxygen sensitivity, altered thylakoid constitution, low photon conversion efficiency, light capture disruption, and the evolution of harmful by-products hinder the sustainability of biohydrogen production processes. High operational and maintenance costs serve as the major bottleneck in the scaling up of the process as an industrial technology. Therefore, future research needs to be directed towards increasing optimization of the processes by reducing energy and resource demand, recycling metabolic wastes and process components, genetically engineered microalgae to adopt more efficient routes, and conducting pilot studies for commercialization. • Wastewater-based microalgae is a potential source of biohydrogen. • Factors affecting the biohydrogen production from microalgal biomass are discussed. • Technologies related to biohydrogen production from microalgae are reviewed. • Key challenges of biohydrogen production process from microalgae are highlighted. [ABSTRACT FROM AUTHOR]

Because of the requirement of the utilization of energy resources in a way that is both effective and efficient, solid oxide fuel cells have become a notable preference due to their advantages such as high efficiency and use with different fuels. In addition, the integration of these systems in the production of alternative fuels such as hydrogen and ammonia are important for a sustainable future to combat environmental problems. For this reason, the main intention of this paper is to introduce a new plant combining the different systems that use the solid oxide fuel cell for a cleaner and sustainable future. In the modeled work, a solid oxide fuel cell, a gas turbine, an organic Rankine cycle, a Kalina cycle with ejector, a hydrogen generation and storage process, a wood steaming plant, and an ammonia production system is integrated, to generate useful products. Detailed thermodynamic modeling is performed through energy and exergy methods, to determine the performance of the advised system and subsystem. Moreover, energy efficiency, exergy efficiency, and exergy destruction analyses methods are applied to each sub-plant and the whole system separately. In addition, parametric research is carried out to examine the effects of modifying key parameters on the plant's and subsystems' performance. Looking at the analysis results, the amount of the hydrogen and ammonia generation capacities of this work are 0.0085 kgs−1and 0.2023 kgs−1, respectively. In addition, the modeled power plant produces a power rate of about 20,180 kW. As a result, this proposed study is calculated to have 61.04% energy efficiency, and 57.13% exergy efficiency. • A novel combined plant with SOFC is developed for hydrogen and ammonia generation. • Modeled system is investigated thermodynamically with energy and exergy efficiencies. • Parametric analysis is conducted to determine the how the effect of each parameter on the system's performance. • Overall energy and exergy efficiency of this modeled plant is 61.04% and 57.13%, respectively. [ABSTRACT FROM AUTHOR]

The current energy supply depends on fossil fuels which have increased carbon dioxide emissions leading to global warming and depleted non-renewable fossil fuels resources. Hydrogen (H 2) fuel could be an eco-friendly alternative since H 2 consumption only produces water. However, the overall impacts of the H 2 economy depend on feedstock types, production technologies, and process routes. The existing process technologies for H 2 production used fossil fuels encounter the escalation of fossil fuel prices and long-term sustainability challenges. Therefore, biohydrogen production from renewable resources like biomass wastes and wastewaters has become the focal development of a sustainable global energy supply. Different from other biohydrogen production studies, this paper emphasizes biohydrogen fermentation processes using different renewable sources and microorganisms. Moreover, it gives an overview of the latest advancing research in different biohydrogen process designs, modeling, and optimization. It also presents the biohydrogen production routes and kinetic modeling for biohydrogenation. • Review on biohydrogen process design, modelling, and optimization. • Comparison of biohydrogen process designs including continuous, batch, or semi-batch processes. • Kinetic equations with optimized parameters are hard to be converted into universal predictive models. • Identification of some possible future research directions. [ABSTRACT FROM AUTHOR]

A typical problem in Northeast China is that a large amount of surplus electricity has arisen owing to the serious photovoltaic power curtailment phenomenon. To effectively utilize the excess photovoltaic power, a hybrid energy system is proposed that uses surplus electricity to produce hydrogen in this paper. It combines solar energy, hydrogen production system, and Combined Cooling Heating and Power (CCHP) system to realize cooling, heating, power, and hydrogen generation. The system supplies energy for three public buildings in Dalian City, Liaoning Province, China, and the system configuration with the lowest unit energy cost (0.0615$/kWh) was obtained via optimization. Two comparison strategies were used to evaluate the hybrid energy system in terms of unit energy cost, annual total cost, fossil energy consumption, and carbon dioxide emissions. Subsequently, the annual total energy supply, typical daily loads, and cost of the optimized system were analyzed. In conclusion, the system is feasible for small area public buildings, and provides a solution to solve the phenomenon of photovoltaic power curtailment. • A novel system implements cooling - heating - power - hydrogen multi-generation. • Hydrogen production of the optimal system is 700 kg per day. • Novel system is superior to existing systems in economy, energy, and environment. • The system conduces to solve the photovoltaic power curtailment phenomenon. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage systems (HydESS) and their integration with renewable energy sources into the grid have the greatest potential for energy production and storage while controlling grid demand to enhance energy sustainability. This paper presents a bibliometric analysis based on a comprehensive review of the highly cited articles on HydESS to provide a detailed insight into future directions and applications. The study was carried out by using the Scopus database search engine to look for filtered keywords in the HydESS and related research. It can be demonstrated that the HydESS literature expanded rapidly from 2016 to 2021 compared to 2011 to 2015. It is found that 89.17% of published articles explained control and test systems-based methods, whereas 10.83% of publications discuss review assessments. Our analysis of highly cited articles on HydESS highlights several aspects, such as methods and systems, issues, difficulties, and challenges to establishing current constraints and research gaps. This evaluation can enhance operational performance, environmental friendliness, energy savings, uninterrupted power supply service, cost benefits, on-site generation, and adaptability. It would be beneficial for technology development and the growth of the hydESS industry. This study may act as a guideline not only for academics in determining the line of research and generating additional discoveries, but also for the government in formulating financial strategies. • Top-cited hydrogen energy storage system articles are reviewed under specific conditions. • Hydrogen storage integrated grids have the potential for energy sustainability. • A historical overview of hydrogen storage was analyzed using the Scopus database. • This survey has exhibited a developing hydrogen storage and renewable energy fields of research. • Bibliometric analysis was used to identify potential future research directions. [ABSTRACT FROM AUTHOR]

The paper provides an assessment of the current wind energy potential in Ukraine, and discusses developmental prospects for wind-hydrogen power generation in the country. Hydrogen utilization is a highly promising option for Ukraine's energy system, environment, and business. In Ukraine, an optimal way towards clean zero-carbon energy production is through the development of the wind-hydrogen sector. In order to make it possible, the energy potential of industrial hydrogen production and use has to be studied thoroughly. Ukraine possesses huge resources for wind energy supply. At the beginning of 2020, the total installed capacity of Ukrainian wind farms was 1.17 GW. Wind power generation in Ukraine has significant advantages in comparison to the use of traditional sources such as thermal and nuclear energy. In this work, an assessment of the wind resource potential in Ukraine is made via the geographical approach suggested by the authors, and according to the «Methodical guidelines for the assessment of average annual power generation by a wind turbine based on the long-term wind speed observation data». The paper analyses the long-term dynamics of average annual wind speed at 40 Ukrainian weather stations that provide valid data. The parameter for the vertical wind profile model is calculated based on the data reanalysis for 10 m and 50 m altitudes. The capacity factor (CF) for modern wind turbine generators is determined. The CF spatial distribution for an average 3 MW wind turbine and the power generation potential for the wind power plants across the territory of Ukraine are mapped. Based on the wind energy potential assessment, the equivalent possible production of water electrolysis-derived green hydrogen is estimated. The potential average annual production of green hydrogen across the territory of Ukraine is mapped. It is concluded that Ukraine can potentially establish wind power plants with a total capacity of 688 GW on its territory. The average annual electricity production of this system is supposed to reach up to 2174 bln kWh. Thus, it can provide an average annual production of 483 billion Nm3 (43 million tons) of green hydrogen by electrolysis. The social efficiency of investments in wind-hydrogen electricity is presented. Image 1 • Assessment of wind potential and electrolysis of green hydrogen in Ukraine. • Ukraine has the potential to build 688 GW of WPP capacity on its territory. • Ukraine can provide 43 m tons of green hydrogen annual production by electrolysis. • Map of potential distribution of annual green hydrogen production in Ukraine. • Investments' social efficiency of in wind-hydrogen electricity. [ABSTRACT FROM AUTHOR]

Conventional productions of large volume of hydrogen from fossil based resources continue to play a key role in the hydrogen economy. This paper recalls the contribution of these conventional technologies with new technological development and researches. Providing gradual integration of renewable solutions into large-scale production, some emerging developments in the use of the renewable based feedstock and energy resources in reforming processes in order to bridge the gaps from conventional use of fossil feedstock to improve various conversion processes were discussed. This paper focuses on high temperature process technologies for producing hydrogen via non-renewable resources and various industrial technologies and processes (700 °C and above) for the beneficiation of the available carbonaceous feedstocks like natural gas, other hydrocarbons (other fossil based options), coal etc. The paper concludes with the analysis of some development gaps in hydrogen production from various resources, which interplays between the renewable and non-renewable resources as well as likely future trends that should be expected in the hydrogen market in the next decades. Image 1 • Wide range of hydrogen utilizations are key drivers to its increasing demand. • Fossil based hydrogen production continues to play dominate role in the hydrogen economy. • By production volume and technological advancement, reforming of natural gas takes the lead. • Non-renewable resources beneficiations via high temperature processes were discussed. • Emerging developments in industrial scale reforming with renewable solutions were assessed. [ABSTRACT FROM AUTHOR]

Hybrid renewable based power generation has emerged as a major breakthrough in electrical power system due to their capability of providing competitive and carbon free electricity to the consumer. This paper presents techno-economic analysis of a grid connected solar photovoltaic-fuel cell based hybrid energy system to supply the electrical load demands of a small shopping complex located at the University campus in India. The proposed system has been designed by considering the cost of energy purchase and sold to the utility grid and further ensuring the smooth power flow management between elements of the system and the utility grid. A simplified mathematical modeling of the proposed hybrid energy system, including power and hydrogen management has been presented to access the potential of hydrogen based energy systems. Component sizing to optimize the net present cost of the proposed system has been performed employing three meta-heuristic algorithms, i.e. , artificial bee colony, particle swarm optimization and a hybrid of both. The experimental results obtained from three algorithms have been compared in terms of cost effectiveness of the system. The hybrid system has been designed to cater the total electricity demand of 135 M W h / y r of a small community center. It has emerged from the simulation results that the total electricity demand could be met with a 106 k W solar photovoltaic, 8 k W fuel cell, 45 k W electrolyzer and a 150 k g of hydrogen tank. The proposed grid connected system has 30 k W grid purchase and 25 k W grid sale capacities, respectively. In this paper, grid sale and purchase capacities have been considered as a decision variable along with other system component sizing. Loss of power supply probability is minimized along with objective function i.e., levelized cost of electricity (LCOE) using the exterior penalty method. It is evident from the results that the proposed system is economically viable with a LCOE of 0.104 $ / k W h. It has emerged from the results that the proposed hybrid energy system may be helpful to promote hydrogen and solar based energy system to reduce the reliance on the overburden grid, particularly, in developing countries. [ABSTRACT FROM AUTHOR]

The growing interest in integrating variable renewable energy resources (RES), besides global concerns about greenhouse pollution, brings multiple challenges for eco and environmentally-friendly operation of systems. Meanwhile, the simultaneous energy supply can improve energy efficiency and mitigate the fluctuation of RES compared with a single-energy system. Therefore, this paper seeks to investigate the optimal scheduling of heating, power, and hydrogen-based microgrid incorporated with RES and plug-in electric vehicles (PEV). The fuel-cell-based hydrogen and electrolyzer facilities are integrated into the multi-energy system to investigate the power-to-hydrogen and hydrogen-to-power technologies in the model. Besides typical electric and thermal loads, the proposed system can directly sell hydrogen to hydrogen-based industrial applications. The PEV as a flexible resource is employed to facilitate the integration of solar energy. Due to the substantial uncertainty from solar energy, price, load, and EVs' arriving and departing times, the risk management of the model based on the conditional value-at-risk is developed to show the operator's behavior against the random inputs and their risk. Results show that integrating the hydrogen storage and plug-in electric vehicle in the model results in a daily cost reduction of up to 9.28%. • Proposing HPH-based microgrid to supply heating, power, and hydrogen energies. • Proposing the comprehensive model for electrolyzer and fuel-cell facilities. • Integrating the plug-in electric vehicle in the multi-energy MG scheduling. • Managing the risk associated with system' uncertainties based on the CVaR. [ABSTRACT FROM AUTHOR]

The hydrogen-based clean energy infrastructure provides a viable option for resilience improvement against extreme events, e.g., natural disaster and malicious attacks. This paper presents a resilience-oriented operation model for industrial parks energized by integrated hydrogen-electricity-heat microgrids, which aims to improve the load survivability under contingency status. The synergies of multi-type distributed energy resources (e.g., fuel cells, hydrogen storage tanks, battery storage and heat storage unit) and the sequential operation of the industrial distribution network are analytically represented by a mixed-integer second-order conic program (SOCP) formulation. Moreover, by leveraging the information of probabilistic disaster prediction, a risk-averse receding horizon method is developed to handle the uncertainty of network contingencies, and supports the optimal decision of proactive and emergency scheduling. Numerical results on a 26-node industrial energy system demonstrate the effectiveness of the proposed model and resilient scheduling method. The synergetic operation of hydrogen-based microgrids could significantly reduce the risks of load interruption. • The resilience of industrial park with hydrogen-based microgrids is studied. • The resilient operation of integrated hydrogen-electricity-heat systems is modeled. • The uncertainty is captured by stochastic scenarios based on probabilistic prediction. • A risk-averse receding horizon method is proposed to support resilient scheduling. [ABSTRACT FROM AUTHOR]

With a relatively high energy density, hydrogen is attracting increasing attention in research, commercial and political spheres, specifically as a fuel for residential heating, which is proving to be a difficult sector to decarbonise in some circumstances. Hydrogen production is dependent on the power system so any scale use of hydrogen for residential heating will impact various aspects of the power system, including electricity prices and renewable generation curtailment (i.e. wind, solar). Using a linearised optimal power flow model and the power infrastructure on the island of Ireland this paper examines least cost optimal investment in electrolysers in the presence of Ireland's 70% renewable electricity target by 2030. The introduction of electrolysers in the power system leads to an increase in emissions from power generation, which is inconsistent with some definitions of green hydrogen. Electricity prices are marginally higher with electrolysers whereas the optimal location of electrolysers is driven by a combination of residential heating demand and potential surplus power supplies at electricity nodes. [Display omitted] • Impact on the power system of hydrogen for heating and a 70% renewable target. • Resulting net emission increase from water electrolysis for hydrogen generation. • The Marginal Abatement Cost of electrolysers is 114.3 euro/tCO2. • Electricity prices increase 1–2% with scale deployment electrolysers. • Power system wide wind capacity factors increase by 0.01 with electrolyser deployment. [ABSTRACT FROM AUTHOR]

Most inhabitants of rural communities in Africa lack access to clean and reliable electricity. This has deprived the rural dwellers access to modern healthcare delivery. In this paper, an off-grid renewable energy system consisting of solar PV and wind turbine with hydrogen storage scheme has been explored to meet the electrical energy demands of a health clinic. The health clinic proposed is a group II with 10 beds located in a typical village in South Africa. First, the wind and solar energy resources of the village were analysed. Thereafter, the microgrid architecture that would meet the energy demand of the clinic (18.67 kWh/day) was determined. Some of the key results reveal that the average annual wind speed at 60 m anemometer height and solar irradiation of the village are 7.9 m/s and 4.779 kWh/m2/day, respectively. The required architecture for the clinic composes of 40 kW solar PV system, 3 numbers of 10 kW wind turbines, 8.6 kW fuel cell, 25 kW electrolyser and 40 kg hydrogen tank capacity. The capital cost of the microgrid was found to be $177,600 with a net present cost of $206,323. The levelised cost of energy of the system was determined to be 2.34 $/kWh. The project has a breakeven grid extension distance of 8.81 km. Since this distance is less than the nearest grid extension distance of 21.35 km, it is established that the proposed renewable energy microgrid with a hydrogen storage system is a viable option for the rural community health clinic. • PV/Wind microgrid with hydrogen storage has been designed for a rural health clinic. • The microgrid was compared with grid extension for decision making purpose. • The capital and net present cost of the microgrid were $177,600 and $206,323. • The project has a breakeven grid extension distance of 8.81 km. • The renewable microgrid is a better option compared to grid extension. [ABSTRACT FROM AUTHOR]

Increasing environmental concerns and decreasing fossil fuel sources compel engineers and scientists to find resilient, clean, and inexpensive alternative energy options Recently, the usage of renewable power resources has risen, while the efficiency improvement studies have continued. To improve the efficiency of the plants, it is of great significance to recover and use the waste heat to generate other useful products. In this paper, a novel integrated energy plant utilizing a geothermal resource to produce hydrogen, ammonia, power, fresh water, hot water, heated air for drying, heating, and cooling is designed. Hydrogen, as an energy carrier, has become an attractive choice for energy systems in recent years due to its features like high energy content, clean, bountiful supply, non-toxic and high efficiency. Furthermore in this study, hydrogen beside electricity is selected to produce and stored in a hydrogen storage tank, and some amount of hydrogen is mixed with nitrogen to compound ammonia. In order to determine the irreversibilities occurring within the system and plant performance, energy and exergy analyses are then performed accordingly. In the design of the plant, each sub-system is integrated in a sensible manner, and the streams connecting sub-systems are enumerated. Then thermodynamic balance equations, in terms of mass, energy, entropy and exergy, are introduced for each unit of the plant. Based on the system inputs and outputs, the energy and exergy efficiencies of the entire integrated plant is found to be 58.68% and 54.73% with the base parameters. The second part of the analysis contains some parametric studies to reveal how some system parameters, which are the reference temperature, geothermal resource temperature and mass flow rate, and separator inlet pressure in the geothermal cycle, affect both energy and exergy efficiencies and hence the useful outputs. • A new geothermal energy based multigeneration system is proposed. • A thermodynamic assessment is carried out through energy and exergy approaches. • The energy and exergy efficiencies of the system are found as 58.68% and 54.73%. • The hydrogen and ammonia production rates are determined as 0.0285 kg/s and 0.1112 kg/s. [ABSTRACT FROM AUTHOR]

Due to the devastating ecological effects and constrained reserves of fossil fuels, renewable energies are now globally accepted as viable alternative sources of energy. Among renewable energy sources, wind energy has become globally popular, primarily because wind farms can be rapidly built and easily maintained at a relatively low cost. Wind-powered hydrogen production is an effective solution for storing the excess energy output of wind farms. The hydrogen produced in this way can be used not only in fuel cells but also in cooling, oil, gas, and petrochemical fields. As a country devastated by war and instability, Afghanistan has major energy generation challenges and a substantially large power supply deficiency. However, there are good wind energy potentials in several parts of this country. There are also several hydrogen-consuming fields in Afghanistan that can benefit from hydrogen production from wind energy. This paper endeavored to distinguish the appropriate areas in Afghanistan for harvesting wind energy for hydrogen production using multi-criteria decision-making techniques. Eleven criteria were utilized to prioritize 20 Afghan provinces with wind energy potential. The Step-wise Weight Assessment Ratio Analysis (SWARA) was utilized to weight the criteria and Evaluation based on Distance from Average Solution (EDAS) were utilized to prioritize the provinces. Then, ARAS, TOPSIS, and VIKOR methods were used to validate the resultants. For criteria weighting with SWARA, "wind speed", "wind power density" and "area of windy regions" with weights of 0.1423, 0.1356, and 0.1221 were introduced as the most significant criteria for this ranking. In all the rankings, Herat, Farah, and Jowzjan were identified as the top three most suitable provinces for wind power generation. The power output and hydrogen output to be achieved in Herat province using a 900-kW turbine were estimated to 2558.4 MW per year and 41.4 tons per year, respectively. • Suitable provinces in Afghanistan is investigated to produce hydrogen. • Wind energy would be used for generating electricity to produce hydrogen. • Different provinces are analyzed in order to rank them. • Multi-Criteria Decision Making (MCDM) methods are used. • Herat, Farah, and Jowzjan are identified as top three most suitable provinces. [ABSTRACT FROM AUTHOR]

The majority of energy being used is obtained from fossil fuels, which are not renewable resources and require a longer time to recharge or return to its original capacity. Energy from fossil fuels is cheaper but it faces some challenges compared to renewable energy resources. Thus, one of the most potential candidates to fulfil the energy requirements are renewable resources and the most environmentally friendly fuel is Hydrogen. Hydrogen is a clean and efficient energy carrier and a hydrogen-based economy is now widely regarded as a potential solution for the future of energy security and sustainability. Hydrogen energy became the most significant energy as the current demand gradually starts to increase. It is an important key solution to tackle the global temperature rise. The key important factor of hydrogen production is the hydrogen economy. Hydrogen production technologies are commercially available, while some of these technologies are still under development. Therefore, the global interest in minimising the effects of greenhouse gases as well as other pollutant gases also increases. In order to investigate hydrogen implementation as a fuel or energy carrier, easily obtained broad-spectrum knowledge on a variety of processes is involved as well as their advantages, disadvantages, and potential adjustments in making a process that is fit for future development. Aside from directly using the hydrogen produced from these processes in fuel cells, streams rich with hydrogen can also be utilised in producing ethanol, methanol, gasoline as well as various chemicals of high value. This paper provided a brief summary on the current and developing technologies of hydrogen that are noteworthy. Image 1 • Alternative energy resources and sustainable energy systems. • Hydrogen demand market and its transmission and distribution briefly discussed. • Hydrogen production methods are reviewed and recent advances were mentioned. • The future directions on hydrogen production were stressed in the conclusions. [ABSTRACT FROM AUTHOR]

Energy, either from non-renewable or renewable sources, is of paramount importance as the progress of a country is gauged on economic development. However, with the use of non-renewable energy resources, the environmental degradation is exacerbating with every passing day in developing countries including Pakistan. On the contrary, the developed countries are resorting to sustainable and renewable energy resources to achieve sustainable development goals. The primary consumer of the non-renewable energy sources is transportation sector in Pakistan, with the total consumption amounting to almost two-third of the total utilization. Keeping in view the existing energy expenditures and its share in environmental pollution by transportation sector, Lahore Metropolitan area has been selected for this research paper. This research analyzed the environmental data collected from multiple road junctions of Lahore City. In light of the existing data, the research exhibited improvements in overall environmental quality by comparing the existing and proposed energy solutions comprising of Hydrogen in transportation sector. The comparison carried out by utilizing International and National Environmental quality standards. Additionally, research also addresses the energy savings with the transition from non-renewable energy sources to renewable and innovative energy solutions. • Environmental degradation is exacerbating with use of non-renewable energy resources. • Primary consumer of non-renewable energy sources is transportation sector in Pakistan. • Comparison of the existing and proposed energy solutions. • Comprising of Hydrogen fuel cell in transportation sector. • Hydrogen fuel cell technologies for the transportation sector for safe and clean future. [ABSTRACT FROM AUTHOR]

Shale gas resources (SGR), as a representative of natural gas hydrate reservoirs, have been the main energy supply for the energy consumption currently. The multi-scale pore structure of shale, complicated seepage mechanisms, including Knudsen diffusion, matrix deformation, stress sensitivity, non-Darcy flow and spatial fracture network stimulated by hydraulic fracturing technology have posed huge challenges to an accurate prediction and assessment of shale gas recovery. A full understanding of gas seepage mechanism of shale gas is the critical and scientific issue to develop carbon hydrogen energy resources effectively. It is very urgent to establish a comprehensive mathematical model to analyze the productivity capacity through simultaneously considering various flow mechanisms and fractures network system. To fill this gap, this paper presents a comprehensive numerical model of hydraulic fracturing horizontal well with discrete fracture network where embedded discrete fracture model (EDFM) is employed to characterize the coupled phenomenon between discrete fracture network and fractured SGR. And then two numerical discretization methods, e.g., finite difference and finite-volume, are used to numerically discretize the equations, subsequently, the Newton-Raphson iterative method is adopted to obtain the final solutions. Finally, the sensitivity analysis experiments are employed to investigate the effects of the key parameters. The results can provide some certain guidance for the optimization of stimulated treatment in natural gas hydrate reservoirs. • Established a comprehensive numerical modelling for multi-stage fractured horizontal well in shale gas reservoirs. • Adsorption, stress sensitivity and non-linear Darcy flow are considered simultaneously in this proposed model. • Validating the new productivity model compared with a simulator. • Relevant parameters and main-dominated factors are significantly analyzed. [ABSTRACT FROM AUTHOR]

With the increasing demand for electricity, more and more fossil fuels are used to generate electricity which leads to energy shortage and environmental pollution. Therefore, using Renewable Energy Sources (RESs) and developing sustainable smart grid have become a common global priority: Since RESs, like solar and wind energy, are inherently unstable, hydrogen energy, as a completely clean new energy, has received widespread attention: I-Energy, which combines information and energy, is a new research direction in smart grid. Furthermore, the household electricity usage accounts for 41% of the total power consumption. Therefore, Household Intelligent Electricity System (HIES), combining hydrogen energy and i-Energy, becomes smart solutions. In this paper, we review the scientific literature for hydrogen energy and i-Energy on HIES, including recognition of electricity appliances, establishment of power consumption model, human activity analysis, smart interactive terminal, home energy management system, distributed power supply and district coordinated power utilization. Finally, we summarize the challenges and give the solutions concerning HIES, and this work can give a useful reference to new energy used model and environment protection. • A new application of Hydrogen Energy on Household Intelligent Electricity System (HIES). • A comprehensive overview of Hydrogen Energy and I-energy on HIES. • Combining internet with traditional electricity to analyses I-energy on HIES. • Summarizing the challenges and corresponding solutions concerning HIES. [ABSTRACT FROM AUTHOR]

In this paper, the significance of CO 2 -free hydrogen is discussed using a long-term global energy system. The energy demand–supply system including CO 2 -free hydrogen was assumed, though there are still large uncertainties as to whether a global CO 2 -free hydrogen energy system will be deployed. System analysis was conducted using the global and long-term intertemporal optimization energy model GRAPE under severe CO 2 emission constraints. Applied global CO 2 constraints for 2050 were a 50% reduction from 1990 levels. CO 2 constraints accounting for Intended Nationally Determined Contributions (INDCs) in each region were also considered. A variety of energy resources and technologies were considered in this model. Hydrogen can be produced from low-grade coal or natural gas with CO 2 capture and electricity from renewable energy. The hydrogen CIF (cost, insurance, and freight) price for Japan was about 3.2 cents/MJ in 2030. Hydrogen demand technologies considered in this paper are hydrogen-fired power plants, direct combustion, combined heat and power (fuel cells, gas engines, and gas turbines), fuel cell vehicles, and hydrogen internal combustion engine vehicles. The majority of CO 2 -free hydrogen was deployed in the transportation sector. CO 2 -free hydrogen was utilized in the power sector, where deployment of other zero emission technology has some constraints. From an economic viewpoint, CO 2 -free hydrogen can reduce the global energy system cost. From the viewpoint of a localized region, such as Japan, deployment of CO 2 -free hydrogen can improve energy security and environmental indicators. [ABSTRACT FROM AUTHOR]

In recent times, more attention is given to renewable and clean energy sources that could ameliorate the current shortage of electricity plaguing South Africa. Due to the comparable use of hydrogen to fossil fuel in the transportation, industrial and electricity sector, hydrogen could be a potential solution to the current energy crises especially when produced from a clean and sustainable source. One of the most appropriate methods of green hydrogen production is the use of wind energy via water electrolysis. This paper therefore investigates the capability and viability of hydrogen production from the wind energy resources of South Africa using the actual wind speed obtained at 60 m anemometer height. Sensitivity analyses are also conducted to gain insight into the possible influences of wind turbine operating parameters on the cost of hydrogen production. Wind regime of fifteen (15) different sites across five (5) major provinces are analysed for possible wind-hydrogen production using eleven (11) different off-the-shelf wind turbines ranging from small to large categories. Some of the key results revealed that the mean wind speed ( V m ) varies from 5.07 m/s in Eston (S12) to 8.10 m/s in Napier (S5). Wind turbine WT 9 (ServionSE MM100) with rated wind power of 2 MW, cut-in wind speed of 2 m/s, rated wind speed of 11 m/s, cut-out wind speed of 22 m/s and turbine hub-height of 100 m has the highest capacity factor (Cf) across all the sites with the values that range from 24.04% in Eston (S12) to 54.55% in Napier. Site S5 presents the best hydrogen production potential with annual hydrogen production that ranges between 6.51 metric-tons with turbine WT 1 and 226.82 metric-tons of hydrogen with turbine WT 11. Wind turbine WT 9 has the least cost of electricity generation ranging from 0.23$/kwh at site S5 to 0.42 $/kwh at site S13. Also, the cost of hydrogen is lowest at site S5 and ranges between 39.55 $/kg using wind turbine WT 1 and 1.4 $/kg using wind turbine WT 11. The sensitivity analysis conducted revealed that rated wind speed has significant effect on the cost of hydrogen production compared to other wind turbine parameters. • Viability of hydrogen production from wind resources of South Africa is studied. • Wind regime of 15 different sites across 5 major provinces are analysed. • Influences of wind turbine operating parameters on hydrogen cost is also considered. • Hydrogen cost is lowest at site S5 from 39.55 $/kg with WT 1 and 1.4 $/kg using with WT 11. • Rated wind speed (vr) has most significant effect on the cost of hydrogen production. [ABSTRACT FROM AUTHOR]

Abstract Hydrogen can compensate for the intermittent nature of some renewable energy sources and encompass the options of supplying renewables to offset the use of fossil fuels. The integrating of hydrogen application into the energy system will change the current energy market. Therefore, this paper deploys the life cycle cost analysis of hydrogen production by polymer electrolyte membrane (PEM) electrolysis and applications for electricity and mobility purposes. The hydrogen production process includes electricity generated from wind turbines, PEM electrolyser, hydrogen compression, storage, and distribution by H 2 truck and tube trailer. The hydrogen application process includes PEM fuel cell stacks generating electricity, a H 2 refuelling station supplying hydrogen, and range extender fuel cell electric vehicles (RE-FCEVs). The cost analysis is conducted from a demonstration project of green hydrogen on a remote archipelago. The methodology of life cycle cost is employed to conduct the cost of hydrogen production and application. Five scenarios are developed to compare the cost of hydrogen applications with the conventional energy sources considering CO 2 emission cost. The comparisons show the cost of using hydrogen for energy purposes is still higher than the cost of using fossil fuels. The largest contributor of the cost is the electricity consumption. In the sensitivity analysis, policy supports such as feed-in tariff (FITs) could bring completive of hydrogen with fossil fuels in current energy market. Highlights • 'Green hydrogen' production cost is calculated on a remote archipelago in UK. • Hydrogen is produced by water electrolyser powered by wind energy. • Hydrogen energy applications include electricity and mobility. • The cost of hydrogen applications are compared with conventional energy supply. [ABSTRACT FROM AUTHOR]

ZnO thin films grown on n-Si substrates using sol–gel spin coating method were annealed in Ar atmosphere at 450 °C, 550 °C and 650 °C temperatures. Three types of Pd/n-ZnO/n-Si/Ti/Al vertical Schottky diodes were fabricated using three types of ZnO films obtained by annealing at the aforementioned three different annealing temperatures for hydrogen gas sensing applications. Using thermal evaporation method, the Pd metals dots were deposited for the Schottky contacts on the annealed ZnO films while Ti and Al were sequentially deposited over the back side of the n-Si for forming the ohmic cathode contact of the diode. The XRD and SEM analyses showed that the structural and surface properties of the ZnO thin films were largely influenced by the annealing temperature. The grain size was observed to be increased with annealing temperature of the ZnO films. The increased grain size at higher annealing temperatures reduces the surface to volume ratio, number of nanoparticles in the ZnO films (and hence the number of Schottky barriers formed between a nanoparticle and Pd) and number of grain boundaries (due to merging of a number of smaller grains into a larger sized grain) which, in turn, affects the hydrogen sensing properties of the devices under consideration. This paper investigates the effects of grain size on the hydrogen sensing property, series resistance and barrier height of the Pd/ZnO film Schottky diodes in details. The highest hydrogen response was observed in the device containing the ZnO film annealed at 450 °C which was attributed to the largest surface to volume ratio owing to the smallest particle size in the ZnO film. [ABSTRACT FROM AUTHOR]

The synthesis of hydrogen distribution networks has been an active area of research over the last two decades. The concept of hydrogen management based on an economic cost-driven analysis appeared late in the 1990s and was followed up by numerous insight-based and mathematical optimisation approaches in the 2000s. More recently, several superstructure-based optimisation methods have been proposed to accommodate pressure restrictions, additional equipment and other practical constraints when finding the optimal flowsheet configuration. This paper provides a state-of-the-art review of different process integration technologies adopted for the assessment of hydrogen resources in refineries and petrochemical plants, published from late in the 1990s to the present time. Both targeting and design methods are reviewed. An effective hydrogen management strategy can only be achieved by combining different insight-based approaches with detailed mathematical programming. [ABSTRACT FROM AUTHOR]

Hydrogen will be an important energy carrier in future energy supplies. Since hydrogen is portable and has a reasonable energy density, hydrogen will be especially important for transportation. However, a vital issue for hydrogen fuel cell vehicles (HFCV) is the safety concerns when hydrogen is leaking from a damaged vehicle after an accident. This paper describes simulations of the use of a portable blower to disperse hydrogen around a leaking vehicle when the blower is in front of the vehicle so that first responders can safely approach the vehicle. The simulations compare well with previous experimental results for a blower in front of the vehicle. The calculations predict the hydrogen concentration distributions around a vehicle for various scenarios to find the most effective solution to provide safe hydrogen levels around the vehicle. The models show that a ground effect blower with the diffuser flush to the floor more effectively removes most of the hydrogen to create a safety envelope around the vehicle. The results also show that the first responders should not approach the vehicle from the side opposite the blower where the hydrogen concentrations would still be close to the lower flammability limit even with a blower. [ABSTRACT FROM AUTHOR]

The focus on pathways to reduce the use of fossil fuels in the transport sector is intense in many countries worldwide. Considering that biofuels have a limited technical production potential and that battery electric vehicles suffer from technical limitations that put constraints on their general use in the transport sector, hydrogen-fuelled fuel cell vehicles may become a feasible alternative. Introduction of hydrogen in the transport sector will also transform the energy sector and create new interactions. The aim of this paper is to analyse the consequences and feasibility of such an integration in Sweden. Different pathways for hydrogen, electricity and methane to the transport sector are compared with regard to system energy efficiency. The well-to-wheel energy efficiencies for hydrogen and electricity are used for estimating the energy resources needed for hydrogen production and electric vehicles for a future Swedish transport sector based on renewable fuels. The analysis reveal that the well-to-wheel system efficiencies for hydrogen fuel cell vehicles are comparable to those of methane gas vehicles, even when biomethane is the energy source. The results further indicate that an increased hydrogen demand may have a less than expected impact on the primary energy supply in Sweden. [ABSTRACT FROM AUTHOR]