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The escalating demand for renewable energy solutions and the imperative for efficient energy storage mechanisms have catalyzed the evolution of Power-to-X (PtX) technologies. Germany has the most PtX projects, accounting for 44% of all projects that have been reported. PtX encompasses a spectrum of processes engineered to convert surplus renewable energy into versatile energy carriers or chemical commodities, such as hydrogen, methane, or synthetic fuels. The Paramount to this domain is to synergistically harness renewable energy sources and hydrogen carriers to curtail waste and bolster sustainability. Central to achieving this synergy is the effective control of PtX processes, ensuring optimal performance, cost efficiency, and seamless integration within existing energy frameworks. This paper delves into the control processes and environmental prerequisites within the PtX landscape, elucidating key challenges, and strategies within this dynamic realm. While providing an initial overview of fundamental PtX process chains, this paper accentuates the critical role of geographical considerations. Subsequently, it conducts a thorough analysis of equipment modeling challenges, addressing performance metrics, operational requisites, and capital investments, particularly focusing on methanol and hydrogen production and storage. Through holistic examination, this paper endeavors to delineate the evolving landscape of PtX control processes and conditions, advancing our understanding of this expanding field. [Display omitted] • Comprehensive overview of PtX control process, challenges, strategies, and advancements. • Overview of PtX process chains and geographical conditions. • Analysis of equipment modeling challenges for methanol and hydrogen. • Addressing crucial storage challenges in PtX system. • Exploration of diverse influences on PtX control processes. [ABSTRACT FROM AUTHOR]

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

The paper is devoted to the development of a device for protecting facilities with turn-to-turn insulation, namely transformers and wind generators in order to increase the reliability of operation of electrical power systems, renewable energy installations and energy storage systems. The paper presents the results of experimental studies of the parameters of a prototype frequency-dependent device, as well as an assessment of the effectiveness of suppression of high-frequency surge voltages by the proposed device. The results of four groups of measurements are shown, which were compared with each other and with the results of previously showed computer simulations. The high efficiency of the proposed device when influencing the slope and amplitude of short high-frequency transients is shown. It is indicated that the parameters proposed earlier in the simulation allow the device to be used effectively. A brief analysis of alternative methods and means of protection is provided, and the prospects for using the device as protective equipment for wind power plants are also considered. [ABSTRACT FROM AUTHOR]

Hydrogen energy is one of promising non-polluting and renewable energy sources. In this paper, we present a first principal study of hydrogen storage in pure C 60 fullerene cage and Stone-Wales (SW) defective C 60 cages using density functional theory (DFT) with applying both the exchange functional B3LYP and the dispersion correction wb97xd at 6–31+g(d,2p) basis set. In addition, the counterpoise correction is applied, and the basis set superposition error is calculated. The calculations underscore that the hydrogenation binding energy of C 60 cages occurs through an endothermal process for C 60 H in with a hydrogen binding energy of 0.09 eV and through an exothermal process for C 60 H out , C 60 SW 66 H out , and C 60 SW 65 H out , cages with hydrogen binding energies of −2.17 eV, −2.96 eV, and −2.20 eV, respectively. Remarkably, for the first time, the intermediate hydrogen binding energy is found inside C 60 SW 66 H in fullerene, and C 60 SW 65 H in fullerene cages with energies of −0.26 eV and −0.81 eV, respectively. The hydrogen adsorption inside the cavity of C 60 SW 66 fullerene cage is thermodynamically possible below 289.8 K and entire pressure range considered. Our results highlight, for the first time, that the endohedral cavity of C 60 SW 66 is a promising new medium for hydrogen storage due to its binding energies (−0.26 eV) and its hydrogen storage weight percentage (5.3%) that are close to the optimal conditions specified by DOE for commercial use. In addition, this study opens up a new discovery of Stone-Wales defective C 60 fullerene for further endohedral cavity applications. • New insight into endohedral cavity of Stone Wales C 60 SW 66 is reported. • For the first time, a new promising medium for hydrogen storage inside cavity of C 60 SW 66 is proved. • Binding energies of −0.26 eV and hydrogen storage weight percentage up to 5.3% are achieved inside the cavity of C 60 SW 66. • This study opens a new discovery of the SW defective C 60 fullerene for further endohedral cavity applications. [ABSTRACT FROM AUTHOR]

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

The shared energy storage system is recognized as a promising business model for the coordinated operation of integrated energy systems (IES) to improve the utilization of energy storage and the consumption of renewable energy. As the hydrogen energy gradually receives more attention, this paper constructs the structure of a hybrid hydrogen energy storage system shared by an IES alliance in a dynamic pricing mode. A bi-level optimization model for the shared hybrid hydrogen energy storage system (SHHESS) is proposed to optimize the capacity configuration decisions and the pricing strategy jointly. The upper level determines the capacity and dynamic price of SHHESS with maximum profits and the lower level obtains the optimal operation of the IES alliance minimizing the total operation costs. The proposed model is solved by an improved PSO-GA algorithm and CPLEX solver. Finally, numerical tests are conducted in different scenarios. The results show that the hybrid energy storage system improves the daily profits of SHHESS by 70.3% and 5.44%, and reduces the renewable energy curtailment by 80.93% and 48.92% respectively compared to the battery-only and hydrogen-only systems. Additionally, the daily operation cost of the IES alliance is 35.2% lower than the individual operation scenario. The proposed model confirms the feasibility and superiority of the hybrid hydrogen energy storage system in a sharing business mode. • Design an interactive structure of a shared hybrid hydrogen energy storage system. • Propose a bi-level planning optimization framework for shared hybrid hydrogen energy storage. • The dynamic price of energy storage sharing service is optimized. • Determine the optimal operation strategy of the integrated energy system alliance. • Propose a hybrid method combining an improved PSO-GA and CPLEX optimizer. [ABSTRACT FROM AUTHOR]

World is presently facing major challenges in energy industry to reduce or replace greenhouse gases (CO 2 , CH 4 , NO x etc.) emissions to net zero in the coming decades while decreasing the reliance on traditional fossil fuels. In the current scenario, hydrogen (H 2) appears to be an excellent alternative energy source to meet the criteria. Storage of H 2 over a long period of time in large quantities poses a significant challenge for its widespread uses. In order to overcome this issue, the idea of using large-scale depleted underground hydrocarbon reservoirs, salt caverns, underground aquifers, etc. is considered to be a suitable option for underground hydrogen storage. However, underground storage of H 2 for a longer time period comes up with a potentially high microbial activity where H 2 can be utilized in the microbial metabolism and converted into undesirable gases like CH 4 and H 2 S which in turn, damage the porous medium due to clogging, acid formation, and corrosion activity. This review paper explores the various scientific challenges during large-scale H 2 storage in porous medium to facilitate the global H 2 economy. Moreover, a detailed description of the effect of subsurface environment conditions such as pressure, temperature, pH, and salinity on microbes is included in this study. In addition to this, steps to counter microbial activity in stored H 2 monitoring and mitigation approaches are also discussed in this article. • Underground hydrogen storage and its mechanism are discussed. • Effect of microorganisms on stored hydrogen and porous media properties comprehensively reviewed. • The impact of microbial activity on subsurface storage environment conditions. • Monitoring and mitigation strategies to counter microbial activities comprehensively reviewed. • Latest treatment proposition of microbial activities and role of biocides in underground hydrogen storage discussed. [ABSTRACT FROM AUTHOR]

Renewable energy production through electrolysis of water to obtain "green hydrogen" has gained interest as a clean energy storage option. However, integrating variable renewable energy resources into the grid poses challenges to maintaining energy balance and stability. In this paper, a hybrid energy storage system combining short-term battery energy storage system and long-term hydrogen-based energy storage system is proposed for an isolated DC microgrid with a structure similar to a hydrogen refueling station. Passivity-Based Control (IDA-PBC) is utilized for power converters regulation, ensuring global stability based on Lyapunov theory while accounting for the nonlinear characteristics of the physical system. The control strategy is designed to ensure a reliable supply of electrical energy to the loads, preserve the quality of electrical variables in the network, and secure the safe operation of system components. Additionally, to safeguard devices from overvoltage, a Sliding Mode Reference Conditioning loop (SMRC) is proposed. It intervenes only when there is a potential risk of exceeding predefined boundaries. Simulations results under demanding conditions demonstrate the effectiveness of incorporating hydrogen energy storage systems with IDA-PBC and SMRC for this class of problems. • An isolated MG with H2 storage, typical structure of a refueling station, was modeled. • The IDA-PBC ensures the stability of the nonlinear and complex MG. • SMRC ensures overvoltage protection in the bus. • The control confirms that H2 storage integrated with RES contributes to MG stability. [ABSTRACT FROM AUTHOR]

Renewable energy systems (RESs) have played a vital role in meeting the continuously fast-rising energy demand. While RESs provide limitless and ecologically good possibilities, putting RESs in place has proven to be a challenging task due to their intermittent energy supply. Battery energy storage systems have widely been used in microgrids to manage the issue of intermittent energy supply caused by the RESs. The disadvantages of batteries include, large size, limited lifespan, and high cost. For this reasons, energy planners are looking into hydrogen-based storage systems as a potential solution. This paper aims to provide the recent advancements in the sizing and energy management of hybrid RES (HRES), as well as conventional methods. To achieve this, the authors have employed a review strategy that involves several specific tasks, such as preparing a database of articles related to Hybrid RESs with hydrogen storage, designing inclusion/exclusion criteria to filter out relevant articles, and analyzing each article from critical viewpoints. Thus, this paper elaborates on the general formulation framework for optimization, the classification and review of different optimization methods, and the literature on the application and research of Energy Management Systems (EMS). Additionally, the review presents an analysis and comparison of various system optimization methods and EMS through a study of several cases from the literature. It is hoped that the review will act as a basic framework for researchers looking to investigate HRES incorporated with hydrogen storage. • An efficient energy storage system is essential for managing intermittent energy supply. • A fuel cell generates electricity by combining hydrogen and oxygen to form water. • Soft computing techniques use both single and hybrid algorithms. • Deterministic rule-based controllers operate based on pre-defined rules. • Energy Management System coordinate the flow of power between different components. [ABSTRACT FROM AUTHOR]

Hydrogen energy storage systems (HESS) play an essential role in Microgrid (MG) systems to address the inherent generation characteristics of renewable energy sources. Also, the integration of Demand Response (DR) into the Energy Management System (EMS) of a renewable-based Multi-Microgrid (MMG) can lead to substantial technical and economic benefits. This paper proposes a modified optimization algorithm for optimizing MMG Energy Management (EM). The proposed algorithm is a modified version of the Student Psychology-Based Optimization (SPBO) technique called Modified Student Psychology-Based Optimization (MSPBO). This modification aims to improve issues such as slow convergence, low solution accuracy, lack of diversity, and getting stuck in local optima. The proposed MSPBO method incorporates a local escape operator and a collaborative student class to achieve a better balance between exploiting known solutions and exploring new possibilities. The MSPBO algorithm is applied to address the EM challenge within a MMG context. Considering the integration of renewable sources as Wind turbines and solar photovoltaic and the HESS, the EM problem is formulated as a two-stage multi-objective optimization: minimizing the operating cost of conventional generators and power transactions cost in addition to the cost of HESS, while maximizing operator benefits and peak load reduction. This multi-objective problem is tackled using a hybrid ε-lexicography–weighted-sum approach that avoids the need for normalization. The performance of the proposed MSPBO is evaluated using CEC 2017 benchmark test functions, utilizing various statistical measures such as best, average, worst, rank, and standard deviation (SD) of fitness values, along with Wilcoxon's rank-sum test. The MSPBO technique is compared with other optimization algorithms for these test functions, highlighting its efficiency and adeptness in achieving a harmonious trade-off between exploiting known solutions and exploring new ones. Furthermore, the MSPBO method is applied to solve two case studies. In Case 1, which involves a single stage with conventional demand response optimization, the results achieved using MSPBO are benchmarked against other optimization techniques, revealing its superior efficacy in addressing the EM challenge. In Case 2, a more complex two-stage multi-objective problem is tackled using MSPBO, and the assessment of the integration of HESS in the MMG is evaluated. In the second stage, there is a notable enhancement in peak load reduction percentage (PRP), from 13.9% to 16.13% without the HESS and from 12.68% to 16.46% with the integration of HESS. [ABSTRACT FROM AUTHOR]

Distribution feeder reconfiguration (DFR) in distribution systems can enhance operating conditions by reducing losses and improving voltage indices. This paper introduces a dual-stage risk-based framework that concurrently tackles day-ahead reconfiguration and microgrid scheduling within the distribution network. To control the negative aspects of uncertainties, the proposed framework integrates energy storage systems (ESS/HSS) and demand response programs (DRPs) at the network level, enhancing adaptability. The initial stage of the proposed model employs the AC power flow model, utilizing loss and voltage deviation functions as objective benchmarks for network reconfiguration. The scheduling is meticulously executed per interval, deriving optimized structures under diverse scenarios with the aid of a case reduction technique (CRT) to streamline solutions. The ultimate solution employs the grey wolf optimization (GWO) algorithm and CPLEX solver in the first and second stages respectively. Outcomes from applying this approach to the adjusted 118-bus network manifest improved operational conditions and voltage quality through reconfiguration. Impressively, the integration of ESS/HSS and DRPs yields a substantial 22.34% reduction in total operating costs, a conclusion substantiated by the numerical findings. Furthermore, by leveraging the CRT, a remarkable 56.17% reduction in problem-solution time is achieved. [Display omitted] • Investigating the impact of losses and voltage deviations on network performance. • Introducing a two-stage risk-based framework to determine the optimal topology. • Finding solutions to the micro-grids planning problem with the distribution network reconfiguration. • Adopting a case reduction method to lessen time demand required for solving the day-ahead planning problem. • Investigating the effect of demand response programs on the voltage characteristics and losses of the system. [ABSTRACT FROM AUTHOR]

Nowadays, renewable energy sources are integral to programs for the development of electric power systems. It is established that modern renewable generation units and energy storage systems utilize power electronic-based interfaces, such as voltage source converters, to convert power. On the one hand, the utilization of a voltage source converter provides certain advantages, such as the absence of a direct link to the network, the ability to operate on all quadrants of the PQ diagram, and the possibility of connecting renewable generation units to a weak network. On the other hand, the widespread use of renewable generation units utilizing voltage source converters reduces the overall inertia of the electric power system. However, excessive use of power electronic converters in the network leads to a significant increase in harmonic pollution, thereby introducing fresh challenges to ensuring safe and stable operation of the electric power system. To ensure the dependable operation of an electric power system with renewable energy sources units and energy storage systems based on the voltage source converter, it is essential to update the control system of the voltage source converter to meet the requirements for traditional generation as part of the electric power system. This paper presents the outcome of the power oscillation damping controller application implemented in the voltage source converter, which enhances the electric power system's stability. [ABSTRACT FROM AUTHOR]

Regional integrated energy systems (RIES) can economically and efficiently use regional renewable energy resources, of which energy storage is an important means to solve the uncertainty of renewable energy output, but traditional electrochemical energy storage is only single electrical energy storage, and the energy efficiency level is low. Hydrogen energy storage has the advantages of large energy storage capacity, long storage time, clean and pollution-free, and can realize the synergistic and efficient utilization of electricity and thermal power. Based on this, this paper proposes a synergistic planning method for an integrated energy system with hydrogen storage taking into account the coupled use of electric-thermal energy, which effectively reduces the system carbon emission and improves the comprehensive energy efficiency level. Firstly, this paper constructs an electric-thermal coupling model of the hydrogen energy storage unit and proposes an optimization strategy for the integrated energy system containing hydrogen storage taking into account the utilization of electricity and thermal power. Secondly, a planning optimization model with the lowest economy and carbon emission and the highest comprehensive energy efficiency was constructed. Third, the CSPO-GE optimization algorithm is proposed for solving the problem, which significantly improves the solution efficiency. Finally, a planning optimization simulation of RIES for a residential community W in northern China verifies the effectiveness of the model and method proposed in this paper. The comparative analysis of the three schemes shows that compared with the integrated energy system with conventional electrochemical energy storage and heat storage tank as the main form of energy storage and the integrated energy system with only hydrogen storage, the integrated energy system with hydrogen storage and heat storage tank can reduce carbon emissions by 43.8% and 7.61%, respectively, and improve the integrated energy efficiency level by 337.14% and 14.44%. • An electrothermal coupled production strategy based on dynamic equilibrium feedback regulation is proposed. • A hydrogen-containing RIES planning and optimization model considering economy-environment-efficiency is constructed. • A multi-objective chaotic particle swarm algorithm (CPSO-GE) based on greedy and elite retention strategies is proposed • The impact of cost variation of hydrogen storage devices on the economics of integrated energy systems is considered. [ABSTRACT FROM AUTHOR]

This paper aims at the development and validation of a computational fluid dynamic (CFD) model for simulations of the refuelling process through the entire equipment of the hydrogen refuelling station (HRS). The absence of such models hinders the design of inherently safer refuelling protocols for an arbitrary combination of HRS equipment, hydrogen storage parameters, and environmental conditions. The CFD model is validated against the complete process of refuelling lasting 195s in Test No.1 performed by the National Renewable Energy Laboratory (NREL). The test equipment includes high-pressure tanks of HRS, pressure control valve (PCV), valves, pipes, breakaway, hose, and nozzle all the way up to three onboard tanks. The model accurately reproduced hydrogen temperature and pressure through the entire line of HRS equipment. A standout feature of the CFD model, distinguishing it from simplified models, is the capability to predict temperature non-uniformity in onboard tanks, a crucial factor with significant safety implications. • CFD model of refuelling through the entire HRS equipment reproduced NREL Test No.1. • Complete hydrogen refuelling process of 195 s simulated in 2 days on 32-core CPU. • The model can be used to design fuelling protocols for HRS with any equipment. [ABSTRACT FROM AUTHOR]

Designing self-sufficient renewable energy systems is becoming a key issue in the energy sector due to modern energy goals. Due to the variability of renewable energy sources, very often it is necessary to adopt hybrid configurations of renewable energy systems and advanced energy storage to achieve self-sufficiency. However, the adoption of complex and novel systems, including technologies as photovoltaic, wind turbines, biomass gasifiers, hydrogen energy storage, must to be founded on a comprehensive analysis of the system operation under different conditions and its energy and economic performance in the investigated case study. Therefore, the aim of the present paper is carry out a comprehensive feasibility analysis of a novel hybrid renewable energy system achieving a high self-sufficiency level. The system integrates a wind turbine and photovoltaic panels to match the energy load of a tourist resort in Agkistro, Greece. Energy exceeding the load is directed to the energy storage system based on the battery and hydrogen tank. As backup energy source, a wood gasifier is used. The investigation is performed by means of a numerical model developed in TRNSYS software allowing one to simulate dynamically the system and to assess its energy and economic performance. The goal achieved during the simulation of the system was to ensure at least 97% of energy demand from renewable sources. Moreover, a parametric analysis of the storage system is presented. It is found that payback period of the installation varies in the range between 11 and 15 years, for systems configurations allowing to satisfy 90–98% of the users energy yearly demand from renewables. The achieved results allows one to evaluate the feasibility of the proposed system from both an energy and economic point of view. • Island energy systems in Greece. • Hybrid energy system with both battery and hydrogen energy storage. • 97% reduction of energy produced from fossil fuels with 30% of energy curtailed. • Parametric study concerning sizes of the energy storage. [ABSTRACT FROM AUTHOR]

Variable Renewable Energy Sources are crucial for decarbonizing industries and efficient energy storage. Hydrogen storage technologies are limited in their large-scale capabilities. PtL technology can synthesize alternative fuels like methanol, which can be used in existing energy infrastructures to produce liquid fuel. The paper presents an innovative approach for utilizing in-situ thermal energy, using a hot reservoir rock (HRR) system for methanol synthesis at high temperature and pressure in an underground large-scale natural reservoir reactor. This approach aims to integrate renewable energy technologies into a single energy generation and fuel production system, including the direct utilization of renewable sources. Solutions from the oil and gas industry can be adapted to this action, such as continuous injection, alternate injection, separate injection, or chemical flooding. Conventional geothermal reservoirs, HDR systems, and depleted hydrocarbon reservoirs can be used as "underground reactors". However, it was also noted that there are challenges, such as catalyst distribution and the complexity of reservoir pore space. • Reservoir rock as a geochemical reactor for underground in-situ e-methanol synthesis. • Synergy between energy storage, CCUS, e-methanol production, and geothermal energy. • Effective use of surplus renewable energy with hydrogen technologies. • Risk reduction related to chemical processing and high environmental neutrality. • Use of resources related to the oil and gas industry for the energy transition. [ABSTRACT FROM AUTHOR]

In a 100% renewable energy scenario, power generation fluctuates, requiring management and control of this generation. Storage is presented as a solution to regulate production discontinuity. In particular, seasonal storage can compensate for long-term fluctuations and serve as a necessary complement to short-term storage management. Due to the potential role of hydrogen in the decarbonization of energy production systems, this research attempts to analyse the levelized cost of storage (LCOS) of this energy carrier as a solution to long-term electricity requirements. The research focuses on the analysis of the total Power-to-Power (P2P) process cost, all factors affecting the input of electricity up to the output of electricity after the conversion of the hydrogen are considered. A transformation of the surplus electricity to hydrogen through a PEM electrolyzer is proposed in this paper. This hydrogen would be stored seasonally in salt caverns. Finally, a gas-to-energy transformation using gas turbines or fuel cells is contemplated. The analysis presents highly competitive results in terms of cost, demonstrating the system's competitiveness and potential: the turbine powered by 100% hydrogen solution appears to be more cost effective than the fuel cell solution: 0.207€/kWh and 0.284€/kWh respectively. Hydrogen storage presents itself as the most cost-effective long-term alternative in the near future, even better than pumped hydro, compressed air or batteries. • LCOS: Levelized Costs of Storage for a large-scale and long-term system. • The use of hydrogen as an energy carrier to store electrical energy from renewable sources at large scale. • Long-term storage of hydrogen in salt caverns. • Transformation of stored hydrogen into electricity through turbine and fuel cells. [ABSTRACT FROM AUTHOR]

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

After a natural disaster, electrical grids might go into a self-healing mode to restore service and reconnect any customers that lost power. In the self-heal system, the fast operation and restoring the critical loads (CLs) during a fault by available resources can increase the flexibility and resilience of the network. In addition to renewable energy sources and electric vehicles (EVs) storage devices, the hydrogen storage system and the process of converting hydrogen into electric energy by micro-gas turbine (MGT) have been modeled in order to assess the impact of this storage system in electrical loads restoration in critical conditions. Self-healing functionality is enhanced by using alternative and novel energy sources. In such a situation, how to interact with the stochastic nature of network components will be challenging. This paper formulates the optimal service restoration (SR) problem using chance-constrained Adaptive Distributionally Robust Optimization (ADRO) to address the ambiguities introduced by the uncertain parameters. A tri-level robust optimization model is developed such that the optimal switching in the network until clearing the fault is determined at the upper level, and the maximization of the SR based on the load demand values is determined at the lower level. The proposed method is demonstrated by simulation results on the modified Civanlar test system. In an equal operating condition and considering β = 3, it can be seen that the initial hydrogen State of the Tank (SoT) by 50 % can improve the load restoration by 7.5 % compared to the uncharged hydrogen tank. By increasing the initial SoT to the nominal value (10 Kg), the load restoration can increase to 13.2 %. [Display omitted] • Customized hydrogen into electric energy conversion model is developed in the energy management field. • Each uncertain parameter is considered ambiguous in the manner that follows an unknown but bounded distribution. • EVs, PHEVs, flexible loads, and the coordinated operation of the hydrogen-to-power system are all taken into account simultaneously. • A tri-level MILP model is formulated to determine the service restoration schedule. • CVaR is employed to effectively deal with the uncertainty of the parameters. [ABSTRACT FROM AUTHOR]

The transition from fossil fuels to renewable energy sources is seen as an essential step toward a more sustainable future. Hydrogen is being recognized as a promising renewable energy carrier to address the intermittency issues associated with renewable energy sources. For hydrogen to become the "ideal" low or zero-carbon energy carrier, its storage and transportation shortcomings must be addressed. This paper will provide the current large-scale green hydrogen storage and transportation technologies, including ongoing worldwide projects and policy direction, an assessment of the different storage and transportation methods (compressed hydrogen storage, liquid hydrogen, blending hydrogen into natural gas pipelines, and ammonia as green hydrogen carrier), as well as economic factors that influence the viability of large-scale green hydrogen storage and transportation. The results of our study highlight several significant findings concerning the cost, challenges, and potential advancements in the green hydrogen storage and transportation field. Our analysis demonstrates that the cost associated with storing and transporting green hydrogen is anticipated to decrease over time due to technological advancements and economies of scale being achieved. However, the commercialization of this technology requires addressing challenges related to storage methods, transportation modes, efficiency optimization, and technology adoption. For example, our research highlights the need for thorough technical and economic evaluations of using salt caverns for hydrogen storage. The efficiency of hydrogen storage and transportation utilizing existing infrastructure, such as storage tanks and natural gas pipelines. By elucidating these aspects, our research contributes valuable insights that can guide future endeavors toward achieving a sustainable and economically viable green hydrogen industry. • Role of government support in green hydrogen storage remains crucial. • Different storage and transportation methods is analyzed and compared. • Cost of hydrogen is expected to decrease for economies of scale. [ABSTRACT FROM AUTHOR]

In this paper, a two-layer hierarchical control strategy for an isolated DC microgrid with a hybrid energy storage system is considered. The DC microgrid studied is composed of a short-term battery energy storage system, long-term hydrogen-based energy storage system and renewable energy resources. The proposed control strategy, combines concepts of Interconnection and Damping Assignment Passivity-Based Control (IDA-PBC) as a primary level and Model Predictive Control (MPC) as a supervisory level. The IDA-PBC layer guarantees a correct power balance and ensures global stability according to Lyapunov theory, considering the non-linear behavior of the physical system. On the other hand, the MPC layer calculates the reference signals for the primary level, ensuring null stationary error in the desired variables. As known, it is important to keep the electrolyzer, the fuel cell and the batteries in a safe operating mode to increase their useful life and guarantee the quality of the hydrogen produced. In this sense, the benefits of MPC are exploited by considering system constraints in the controller design. The main objective of the two-layer control strategy is to ensure the supply of electrical energy to the loads and quality in the electrical variables of the network. Representative simulation results under demanding conditions verify the effectiveness of combining IDA-PBC and MPC for this class of problems. • An isolated MG with H2 storage, typical structure of a refueling station, was modeled. • The hierarchical control strategy successfully combines IDA-PBC and MPC techniques. • The IDA-PBC ensures the stability of the nonlinear and complex MG. • Supervisor MPC ensures zero stationary error and safe operating mode of the MG. • The control confirms that H2 storage integrated with RES contributes to MG stability. [ABSTRACT FROM AUTHOR]

This paper presents a framework for the efficient design and evaluation of a standalone hybrid renewable energy system (HRES) to meet the energy requirements of a rural community in the north-eastern region of Nigeria. The proposed microgrid system incorporates solar photovoltaic, wind turbines, biomass gasifier, fuel cell, and Battery storage. The sizing of each component is determined through the utilization of real local meteorological data and the load demand over a year, employing the Levy flight-salp swarm algorithms (LF-SSA). The optimization objective is to minimize the annualized system cost (ASC) of the HRES, while also considering the reliability constraint of Loss of power supply probability (LPSP). The comparative outcomes demonstrate that the LF-SSA surpasses other examined algorithms, namely the salp swarm, genetic algorithm, and HOMER software by achieving substantial cost savings of $29033, $50796, $191771 respectively in relation to the proposed HRES. The result further shows that, the LF-SSA provides the lowest LCOE of $0.933162/kWh, in contrast to SSA at $0.947737/kWh, GA at $0.958660/kWh, and HOMER at $1.075351/kWh. Additionally, the results indicate that the implemented Energy Management System (EMS) has successfully facilitated the establishment of an environmentally friendly and cost-effective energy system. • An efficient energy storage system is essential for managing intermittent energy supply. • The fuel cell can generate DC power by combining hydrogen with oxygen. • The amount of power generated by a PV panel depends on temperature and solar radiation intensity. • Deterministic rule-based controllers operate based on pre-defined rules. • Energy Management System coordinate the flow of power between different components. [ABSTRACT FROM AUTHOR]

This paper aims to provide a holistic analysis of the role of hydrogen for achieving greenhouse gas neutrality in Germany. For that purpose, we apply an integrated energy system model which includes all demand sectors of the German energy system and optimizes the transformation pathway from today's energy system to a future cost-optimal energy system. We show that 412 TWh of hydrogen are needed in the year 2045, mostly in the industry and transport sector. Particularly, the use of about 267 TWh of hydrogen in industry is essential as there are no cost-effective alternatives for the required emission reduction in the chemical industry or in steel production. Furthermore, we illustrate that the German hydrogen supply in the year 2045 requires both an expansion of domestic electrolyzer capacity to 71 GW H2 and hydrogen imports from other European countries and Northern Africa of about 196 TWh. Moreover, flexible operation of electrolyzers is cost-optimal and crucial for balancing the intermittent nature of volatile renewable energy sources. Additionally, a conducted sensitivity analysis shows that full domestic hydrogen supply in Germany is possible but requires an electrolyzer capacity of 111 GW H2. • 412 TWh of hydrogen demand in a greenhouse gas neutral Germany in the year 2045. • Hydrogen usage is crucial for defossilization of chemical and steel industry. • 47% of hydrogen is imported from other European countries and Northern Africa. • 71 GW H2 of electrolyzer capacity in Germany with flexible operation. • 35 TWh of hydrogen storage in salt caverns for security of supply. [ABSTRACT FROM AUTHOR]

Optimal energy management of microgrids enables efficient integration of renewable energies by considering all system flexibilities. For systems with significant seasonal imbalance between energy production and demand, it may be necessary to integrate seasonal storage in order to achieve fully decarbonized operation. This paper develops a novel model predictive control strategy for a renewable microgrid with seasonal hydrogen storage. The strategy relies on data-based prediction of the energy production and consumption of an industrial power plant and finds optimized energy flows using a digital twin optimizer. To enable seasonal operation, incentives for long-term energy shifts are provided by assigning a cost value to the storage charge and adding it to the optimization target function. A hybrid control scheme based on rule-based heuristics compensates for imperfect predictions. With only 6% oversizing compared to the optimal system layout, the strategy manages to deliver enough energy to meet all demand while achieving balanced hydrogen production and consumption throughout the year. • PV with seasonal H 2 storage enables fully sustainable operation of industrial microgrids. • Model predictive control overcomes perfect foresight limitation in energy management. • H 2 production for long-term storage is incentivized by adding an extra cost term. • Hybrid predictive control enables a low cost system with nearly perfect yearly operation. [Display omitted] [ABSTRACT FROM AUTHOR]

The paper proposes the analysis of four different scenarios of renewables penetration (40%, 60%, 80%, and 100%) with the most affordable generators: photovoltaic panels and wind turbines. The synergy of two storage technologies, such as Li-Ion batteries and the hydrogen power-to-power solution (electrolyzer, H 2 tank, and fuel cells), is evaluated to ensure the balance of the power-grid. The paper discusses the numerical Trnsys-based modeling of the smart grid. A detailed performance evaluation of each component, according to operational maps provided by manufacturers, has been performed to meet an electrical load (10 MW peak - 54 GW h annual). The results of the analysis show the crucial role of the H 2 system in the goal of achieving a higher renewable fraction, mainly due to the possibility of seasonal storage without the self-discharge limitation of batteries. In the 100% renewable solution the contribution of H 2 is equal to 30% of the electric load. • The synergy of Li-Ion batteries and hydrogen is evaluated to ensure grid balance. • Hydrogen integration has been evaluated in the path to 100% renewable energy. • The optimum solution is a tradeoff between renewable share and system cost. • A fully renewable system would cost $0.42/kWh with a 30% hydrogen contribution. • Hydrogen power-to-power system is strongly limited by high cost. [ABSTRACT FROM AUTHOR]

The most important hydrogen energy storage technologies, developed between 1974 and 2022, now enable the quality operation of global power grids that integrate alternative energy facilities (wind power, solar power, geothermal power, etc.). With the continuous large-scale penetration of converter-interfaced generation (CIG), based on the combined use of renewable energy sources (RES) and hydrogen energy storage systems (ESS), into practical power systems, the dynamic characteristics of the latter change significantly. New challenges with the power system control and stability arise due to the specific CIG properties. A positive-sequence time-domain simulation is frequently used to solve them. However, the known simplifications and limitations are inevitably applied in case of such simulation. These become critical for the CIG with RES and hydrogen ESS models due to their fast dynamics. Therefore, the validation of such simulation results becomes relevant. This paper proposes a novel validation approach based on the use of a benchmark tool Hybrid Real-Time Power System Simulator (HRTSim) instead of field measurements. A major feature of the proposed approach is the possibility of a guaranteed validation of the benchmark tool using any state of the modeled power system. A hybrid implementation of a detailed three-phase model of CIG is also developed for the HRTSim, which provides an adequate simulation of the full range of dynamic processes. The results of validation of a positive-sequence simulation of a practical power system with CIG, which includes both RES and hydrogen ESS, using the developed approach presented in this paper have allowed to identify the causes of calculation errors, as well as factors affecting them. [ABSTRACT FROM AUTHOR]

The paper proposes a methodology for designing intelligent systems of autonomous distributed hybrid power complexes (ADHPC) ensuring a minimum level of energy consumption from the national external grid as well as diesel power plants used to deliver the power to regional households, and industrial consumers. It will be realized because of the effective use of generated energy from renewable energy sources in such ADHPC systems by considering their both normal and emergency operating modes. In doing so, ADHPC will not only help offload the existing power grid during peak demand, but also allow for significant process efficiencies in energy production from renewable energy sources (RES), including "green" hydrogen: for instance, the excess energy is accumulated during the period of its excess and is provided back to power consumers in the period of shortage, the electricity losses are reduced since effective management is applied for power flows circulating in the ADHPC systems. The methodology includes the following stages (subtasks): development of the structure of a distributed hybrid system for generating and transporting electricity from sources to consumers; development of a system for diagnostics of failures of generating units and wire breaks in sections of local power transportation networks and management based on the diagnostics results of power flows circulating in the ADHPC systems for both normal and emergency modes. Therefore, a balance of power capacities and minimization of their losses are ensured. [ABSTRACT FROM AUTHOR]

Integration of renewable energy sources (RES) together with energy storage systems (ESS) changes processes in electric power systems (EPS) significantly. Specifically, rate of change and the lowest values of operating conditions during the emergencies are got influenced. Such changes can cause incorrect actions of relay protection (RP) as it was designed and adjusted with no regard for influence of RES and ESS. Detailed research on processes during the different normal and abnormal modes in both EPS and primary transducers and also in RP devices should be done to take preventive actions. To do this research mathematical modeling based on detailed and authentic models of all elements including RP should be used. HRTSim (which was developed by authors) software for simulating EPS provides the opportunity to create such models of EPS of any size without simplifications and limits. Using of this instrument together with detailed mathematical models of RP which were developed before provided the opportunity to investigate them rigorously in RES-integrated EPS. Settings providing adequate action of RP in certain conditions were performed as a result of this investigation. Fragments of these investigations are performed in this paper. Results of these investigations would be useful for designing new methods and tools of RP adjustment. General structure of a grid-connected combined renewable energy system with a hydrogen storage system. [Display omitted] [ABSTRACT FROM AUTHOR]

Considering the high calorific value and low-carbon characteristics of hydrogen energy, it will play an important role in replacing fossil energy sources. The production of hydrogen from renewable energy sources for electricity generation and electrolysis of water is an important process to obtain green hydrogen compared with classic low-carbon hydrogen production methods. However, the challenges in this process include the high cost of liquefied hydrogen and the difficulty of storing hydrogen on a large scale. In this paper, we propose a new route for hydrogen storage in metals, namely, electricity generation from renewable energy sources, electrolysis to obtain metals, and subsequent hydrogen production from metals and water. Metal monomers facilitate large-scale and long-term storage and transportation, and metals can be used as large-scale hydrogen storage carriers in the future. In this technical route, the reaction between metal and water for hydrogen production is an important link. In this paper, we systematically summarize the research progress, development trend, and challenges in the field of metal to hydrogen production. This study aim to aid in the development of this field. • A new route for hydrogen storage and production via metals on a large scale is proposed. • Electrolysis to obtain metals by green electricity, and subsequent hydrogen production from metals and water. • Metal monomers facilitate large-scale and long-term storage and transportation. • Metals can be used as large-scale hydrogen storage carriers in the future. • Metal-water hydrogen production can make full use of renewable energy without carbon dioxide. [ABSTRACT FROM AUTHOR]

The substitution of fossil fuels with renewable energy sources such as hydrogen is a decisive factor in making aviation environmentally compatible. A key parameter for the use of hydrogen is the storage system. In the design of a flight-capable storage system, not only the mass but especially the volume of the hydrogen has to be considered. Therefore, in this paper different techniques are compared and evaluated from the point of view of their application in aircraft design. The analyses are performed on two reference aircraft, the Airbus A320 and the Embraer E 190, in the short- and medium-haul range. Simplified, it is assumed that the respective max. Take-off mass (MTOM) remains constant. The change of the necessary periphery has no influence on the MTOM. A tank concept could be designed, which can find applications in today's conventional aircraft design. • Energy consumption calculated for A320 and E 190. • Flight data evaluation. • Comparison of different storage methods. • Calculation of volumes for different storage methods and ambient pressures. • Discussion about possible constructive misplacement. [ABSTRACT FROM AUTHOR]

In this paper, a multi-objective mixed-integer linear programming model is developed to design a hybrid PV-hydrogen renewable energy system considering two objective functions; minimizing total life costs and loss probability of power supply. The decisions of the hybrid system include the number of PV panels, the number of hydrogen tanks, the number of electrolyzers, the number of fuel cells, and quantity of hydrogen stored over time. An exact method embedded in GAMS software is used to solve the developed model. The model is validated using an electrical testing lab in Saudi Arabia with hourly power demand. Different plans are chosen from the obtained optimal Pareto solutions. For example, one of the plans found that a hybrid system with 212 PV panels, 617 hydrogen tanks, 30 electrolyzers, and 21 fuel cells is sufficient to satisfy the electrical testing lab load with an annual cost of $61663, the loss of power supply probability is 10%, and the CO 2 saving of 214,882 kg of CO 2. The results indicated the feasibility of combining an electrolyzer, hydrogen tank storage, and fuel cell with a renewable energy system; however, the cost of energy generated is still high because of the high investment cost. Furthermore, the findings revealed that hydrogen technologies are appealing as an energy storage solution for intermittent renewable energy systems and in other applications such as transportation, residential, and industrial sectors. In addition, the findings demonstrated the possibility of using renewable energy as a source of energy, namely, in Saudi Arabia. However, weather conditions, geomorphological conditions, and climatic dependence on hydrogen fuel cell technology can harm the energy yields produced by renewable energy systems. • Design a multi-objective hybrid PV-Hydrogen storage renewable energy system. • Evaluate the performance of the proposed model based on a real case study. • Help the decision-maker in analyzing alternative trade-offs. • The LCOE ranges between 0.143 and 0.160 $/kWh for generated plans. • The annual CO 2 savings range between 197,351 and 227,905 kg of CO 2. [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]

Currently, there is a large-scale penetration of renewable energy sources (RES) in power systems around the world, most of which are based on the power converter technology. The result of such penetration is the emergence of frequency and voltage regulation problems in power systems with RESs. An effective way to solve the mentioned problems is the use of energy storage systems (ESS), among which hydrogen ESSs are promising. However, the quality of such solution mainly depends on the approach to the power converters control. One of the most effective is a grid-forming power converter control strategy. Within this strategy, many scientific groups have proposed the concept of a virtual synchronous generator (VSG). However, the existing VSG models use a series structure with a stiff direction of signals, which completely mimics conventional synchronous generators. In this regard, the fundamental problems inherent in such a structure arise, e.g., a coupling between active and reactive power control. This paper describes a freely configurable VSG model (FC-VSG), in which the structural control blocks can be transferred from one level to another, and the levels themselves can be installed not only in series, but also in parallel. The case studies carried out made it possible to identify the configuration of the FC-VSG, which excludes the fundamental problems inherent in the conventional VSG structures. At the same time, the most efficient and reliable frequency and voltage regulation is provided, which has been proved by qualitative and quantitative comparison, including with the conventional VSG structure. [ABSTRACT FROM AUTHOR]

Environment-friendly, safe and reliable energy supplies are indispensable to society for sustainable development and high life quality where even though social, environmental, political and economic challenges may play a vital role in their provision. Our continuously growing energy demand is driven by extensive growth in economic development and population and places an ever-increasing burden on fossil fuel utilization that represent a substantial percentage of this increasing energy demand but also creates challenges associated with increased greenhouse gas (GHG) emissions and resource depletion. Such challenges make the global transition obligatory from conventional to renewable energy sources. Hydrogen is emerging as a new energy vector outside its typical role and receiving more recognition globally as a potential fuel pathway, as it offers advantages in use cases and unlike synthetic carbon-based fuels can be truly carbon neutral or even negative on a life cycle basis. This review paper provides critical analysis of the state-of-the-art in blue and green hydrogen production methods using conventional and renewable energy sources, utilization of hydrogen, storage, transportation, distribution and key challenges and opportunities in the commercial deployment of such systems. Some of the key promising renewable energy sources to produce hydrogen, such as solar and wind, are intermittent; hydrogen appears to be the best candidate to be employed for multiple purposes blending the roles of fuel energy carrier and energy storage modality. Furthermore, this study offers a comparative assessment of different non-renewable and renewable hydrogen production systems based on system design, cost, global warming potential (GWP), infrastructure and efficiency. Finally the key challenges and opportunities associated with hydrogen production, storage, transportation and distribution and commercial-scale deployment are addressed. • A detailed review on hydrogen production methods and utilization. • Green, blue and purple hydrogen production methods are described thoroughly. • Hydrogen storage and infrastructure, transportation and distribution are also covered in utilization. • Recent advancements, challenges and opportunities are described in detail. • Comparative assessment is conducted on the basis of system design, cost, storage, GWP, infrastructure and efficiencies. [ABSTRACT FROM AUTHOR]

Overreliance on fossil fuels for human energy needs, combined with the associated negative environmental consequences in terms of greenhouse gas emissions, has shifted our focus to renewable energy sources. Hydrogen has been identified by researchers as an energy source. Hydrogen is a non-carbon-based energy resource that has the potential to replace fossil fuels. This resource is seen as an alternative fuel since it may be produced using environmentally friendly methods. Hydrogen storage is a critical component of the hydrogen economy, particularly when hydrogen utilization on a large scale is required. This paper presents a review of worldwide underground operating and potential sites to provide a clear understanding of the current status of hydrogen storage in the world. The literature survey indicated that underground geological structures have been used to successfully store hydrogen. Some of the criteria used to select these sites for underground hydrogen storage include but are not limited to geological conditions, storage location, availability of brine, presence of insoluble impurities such as dolostone, limestone, or shale, and socio-economic characteristics. The key issues with the hydrogen storage in the subsurface geological structures include but are not limited to microbial, hydrogeological, hydrodynamics, geomechanics, and geochemical facilitated by injected hydrogen which significantly impact the success and operational efficiency of the projects. • Discussion on operating and potential hydrogen storage sites. • Geological aspect of the storage formations with emphasis on reservoir and caprocks. • Road map for underground hydrogen storage. • Hydrogen storage sites including depleted oil and gas, aquifers, and caverns/salt domes. [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]

In this paper, the robust capability of HOMER and Criteria-COPRAS is deployed to explore the prospect of selecting a renewable energy system. The energy system consisting of wind turbines, solar photovoltaic (PV), fuel cell (FC), electrolyzer, hydrogen storage, and battery energy storage is intended to power a residential load in Lagos Nigeria. Based on the economic metric, the results show that the optimal system is a PV-Battery whose total net present cost (TNPC) and initial investment cost are $9060 and $3,818, respectively. However, if the energy systems are ranked based on multiple criteria (economic, technical and environmental aspects), the most preferred of the feasible energy systems is a hybrid PV-FC-wind-battery (TNPC-$10,324, initial cost: $7670). The study results indicate that, for viability in the adoption of hydrogen energy storage as part of the hybrid energy system, the selection metric should be based on more than one criterion. [Display omitted] • Optimal sizing of off-grid hybrid renewable energy systems for a residential building is presented. • A combination of hydrogen tank and battery were proposed as backups. • Energy systems were ranked using complex proportional assessment (COPRAS). • PV-battery was ranked best using single criterion. • Hybrid combination of Photovoltaic-Wind Turbine-Fuel cell-Battery was ranked best based on multiple criterion. [ABSTRACT FROM AUTHOR]

Penetration of renewable energy sources (RESs) in power systems increase all over the world to overcome current challenges, most importantly environmental issues. Beside advantages of RESs, their integration into the power systems have imposed various challenges considering uncertain and intermitted power output. To cope with these challenges, utilizing energy storage systems with renewable energy sources alongside the demand response (DR) programs are considered as reliable solutions. On the other hand, in an uncertain environment, minimizing worst-case cost or regret is counted as an important criterion to evaluate operation of any system under uncertain parameters. Therefore, in this paper, optimal operation of power systems is solved under penetration of wind turbines, hydrogen storage system, and DR programs in an uncertain environment. To guarantee robust operation of the system under the worst-case scenario, a novel stochastic p-robust optimization method (SPROM) is proposed which combines both stochastic programming and robust optimization approaches where minimizes the worst-case cost or regret level. The performance of the developed model is evaluated considering a six-bus test system under two cases as stochastic optimization (SO) and SPROM. Obtained results show that the maximum regret level is reduced considerably using the proposed SPROM comparing with pure stochastic method. • Security-constraint unit commitment problem is solved considering wind generation. • Hydrogen storage system and renewable energy sources are integrated in power system. • Stochastic p-robust optimization method is proposed to get robust operation. • Expected total operating cost of the system is minimized under worst-case scenario. • Maximum level of relative regret in system is minimized under worst-case scenario. [ABSTRACT FROM AUTHOR]