Search

Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH 4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH 4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H 2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH 4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides. [Display omitted] • Ni–CoP catalyst was electrodeposited on a carbon support. • Material characterization proved the formation of desired active layers. • High efficiency and stability of the catalyst for a long-term NaBH 4 hydrolysis was revealed. [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]

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]

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

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]

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

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]

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]

The world is moving rapidly to embrace renewable energy sources. One energy carrier, hydrogen, is a growing player in this field. This study was motivated by a desire to find alternative hydrogen storage mechanisms using processes that are cost effective with low environmental impact and good energy storage efficiency. This paper presents initial research findings on the novel approach of employing the patented RMIT Proton Battery to store atomic hydrogen in a multilayer graphene electrode using an acid electrolyte. This is a very different approach to conventional hydrogen energy storage systems. The paper reveals that one supplier's product achieves a 0.35 wt% reversible hydrogen storage in a multilayer graphene material with 0.35 nm layer separation and a specific surface area of 720 m2/g. [Display omitted] • Multilayer Graphene is a potential material for electrochemical hydrogen storage. • Hydrogen storage of a commercial sample in a Proton Battery unit is reported. • Criteria to synthesise novel electrodes with improved H storage are established. [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]

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]

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

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 increasing heterogeneity and scalability of the Internet of everything, especially, the Energy Internet (EI), is a prompt for novel engineering paradigms. The current infrastructure of hardware technologies besides the available software stack is becoming obsolete for handling the advanced requirements of the smart energy ecosystem. Accordingly, software definitions of the Internet of Things (IoT) stack functions are gaining interest to provide more flexible and scalable implementations. This paper investigates a sophisticated softwarization explicit hybrid model predictive control strategy for energy storage facility systems through the accessor design pattern. This strategy is presumed to support and facilitate the integration of higher-level analytic and control functionalities within the IoT stack at edges and nodes. Simulation is conducted with the Ptolemy II software to evaluate the execution semantics of the proposed strategy. In addition, real-time experiments on a lab-scale hydraulic tank process with both abrupt and gradual commands test scenarios showed the efficiency and reliability of the accessor-based controllers for achieving the control objectives for the benchmark storage facility with an abstract implementation. The analysis shows that this process can serve as a benchmark to mimic the charge and discharge cycles of storage elements in EI ecosystems. • A new paradigm for hydrogen energy storage interfacing within energy Internet ecosystems is proposed and investigated. • An actor-oriented approach is applied for implementing real-time control systems of hydrogen storage. • Software-defined model predictive control is implemented within a Node.js accessor host. • A benchmark process is developed as an emulator for hydrogen energy storage to evaluate the accessors design pattern. [ABSTRACT FROM AUTHOR]

Direct air capture of carbon dioxide (CO 2) is technically a feasible solution for reducing atmospheric CO 2 concentrations at scale, building on decades of global research. However, powering such systems even partially with CO 2 -intensive fossil fuels results in more CO 2 emissions. This paper presents a novel energy management strategy (EMS) to further explore modular offshore wind energy off Canada's West Coast via power-to-direct air capture and power-to-gas systems. The system architecture includes a 15 MW wind turbine paired with a hydrogen energy storage system, i.e. hydrogen production and storage, and direct air capture (DAC) units. Hydrogen production from wind generation is stored and used to offer two key benefits: to deliver the thermal loads of the DAC system, and to meet hydrogen demand for external consumers. The proposed EMS offers an extra degree of freedom to operate the designed system by setting the priority either to maximize the amount of CO 2 capture or to maximize the amount of H 2 production for external consumers. In particular, the study incorporates dynamic mathematical modeling and constraints formulation for the aforementioned scenarios; DAC priority for CO 2 capture and H 2 for external hydrogen demand satisfaction. The effectiveness of the proposed EMS is shown through extensive simulations with different seasonal conditions. • Detailed mathematical dynamical models for offshore power-to-DAC and power-to-gas systems. • Green hydrogen production for two-fold benefits; H 2 for meeting DAC thermal loads, and H 2 as fuel for external consumers. • Scenario 1 prioritize the CO 2 capture rate, while scenario 2 maximizes the H 2 production for external consumers. • Design of EMS shows the correct unit commitment of the CO 2 capture rate and H 2 tracking. [ABSTRACT FROM AUTHOR]

The presence of distributed energy sources in integrated energy systems make it difficult to meet the real-time balance between supply and demand, requiring the deployment of energy storage systems. Hydrogen storage can compensate for the lack of electrochemical energy storage in the energy, time and space dimensions. Meanwhile, the cooperative operation of participants within an integrated energy system, compared to individual operation, can help generate additional benefits and reduce carbon emissions. Therefore, this paper proposes a method for optimising the operation of integrated energy systems based on a cooperative game containing hydrogen energy storage systems. Firstly, a model for optimising the operation of an integrated energy system with hydrogen storage energy system considering the revenue from hydrogen sales is constructed. Secondly, a benefit allocation mechanism for the cooperative game based on the shapley value method is proposed. Finally, the BPSO-SA optimisation algorithm is proposed for solution. The total operating cost of the collaborative operation scenario is reduced by 22.96% and the carbon emissions are reduced by 80.11% compared to the independent operation scenario, the operating cost savings and carbon emissions reduction are allocated to the participants according to their contribution, encourage participants to build integrated energy systems through collaboration. • A model for optimising the operation of an IES containing hydrogen energy storage system is developed. • A multi-participant cooperative game benefit allocation mechanism within the IES is developed. • A hybrid particle swarm optimisation-simulated annealing based on beetle antennae search strategy (BPSO-SA) is proposed. [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]

Hydrogen energy storage system (HESS) has excellent potential in high-proportion renewable energy systems due to its high energy density and seasonal storage characteristics. After detailing the volatility of wind speed, irradiance and load, this paper proposes a bi-level optimization model to analyze the economic operation of the wind-photovoltaic-hydrogen hybrid system (WPH-HS). First, the relationship between the source-load output matching and operating conditions of HESS is studied, two evaluation indicators are described, which can be adjusted by wind-solar complementarity on the source side and demand response on the load side. Second, considering the levelized cost of storage (LCOS), the total annual cost (TAC) calculation method of WPH-HS is presented, and this paper provides a new hybrid optimization technology of chaotic search, particle swarm optimization and non-dominated sorting genetic algorithm2. Finally, the system is simulated with the MATLAB software to determine the optimal sizing of components and minimize the LCOS while ensuring the optimal TAC. The simulation results are elaborated in detail. In particular, the added source-load interaction reduces the TAC and LCOS by 7.3% and 10.3%. When two indicators reach 0.03 and 0.1745, the system is economically viable with the LCOS of 0.276 USD/kWh. The hybrid optimization algorithm can achieve better result in fewer iterations. • The cross-season utilization of the hydrogen energy storage system is discussed. • A price bi-level model about the levelized cost of storage and the total annual cost is established. • Evaluation indicators are presented to promote the source-load interaction. • Effects of wind speed, irradiance, and loads are investigated for the levelized cost of storage. • A hybrid optimization algorithm based on three common algorithms is designed. [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]

Environmentally friendly and pollution-free hydrogen cell, battery and supercapacitor hybrid power system has taken the attention of scientists in recent years. Several notable advancements in energy storage mechanisms with hybrid power systems have been made during the last decade, influencing innovation, research, and the possible direction for improving energy storage technologies. This paper represents a quantitative analysis of all knowledge carriers with mathematical and statistical methods of hydrogen energy storage to establish a hybrid power system. For selecting the top cited papers in this topic, related articles on energy storage mechanisms for hybrid power systems were searched in the Scopus database under specified predetermined parameters. The selection technique of the most cited paper was based on filtered keywords in the hybrid hydrogen energy storage-based hybrid power system and related research during 2008–2021. About 48% of all articles have been published between 2016 and 2019; 21% will have originated from China; and 29% of the papers have used batteries as a form of energy storage in the application of electric vehicles. Most of the articles contain experimental work (25.11%) followed by simulation analysis (25%) and systematic and nonsystematic review (18.75%). Related publications with the most citations were published in 35 different impactful journals from different publishers and nations. This research found that integrating hydrogen energy storage with battery and supercapacitor to establish a hybrid power system has provided valuable insights into the field's progress and development. Moreover, it is a thriving and expanding subject of study. Bibliometric analysis was used to identify the most significant research publications on the subject of hybrid energy storage, mapping the multidisciplinary character, illustrating nature and trends, and outlining areas for further research. The process of collecting, selecting, and analyzing the most cited articles is expected to contribute to a methodical foundation for future developments of hydrogen energy storage systems and provide viable research paths toward attaining a hybrid power system. • Hydrogen-battery-supercapacitor hybrid power system made notable advancements. • A statistical analysis of hydrogen storage integrated hybrid system is demonstrated. • Top cited papers were searched in Scopus database under predetermined parameters. • Challenges and recommendations are highlighted for future energy applications. • Bibliometric analysis was used to identify potentials for future research directions. [ABSTRACT FROM AUTHOR]

In front of the opportunity of the rapid development of renewable energy power generation, energy storage is playing a more important role in improving its utilization efficiency. In this paper, a hybrid energy system based on combination of hydrogen fueled compressed air energy storage system and water electrolysis hydrogen generator is proposed. The superfluous renewable energy power is charged by compressing the air and/or producing hydrogen through water electrolysis. A hydrogen combustor is introduced to raise the air temperature in the discharging process. A thermodynamic model of the proposed system is built. Energy and exergy analysis found that under the design condition, the proposed system can achieve a round trip efficiency of 65.11%, an exergy efficiency of 79.23%, and an energy storage density of 5.85 kWh/m3. The exergy loss of water electrolysis hydrogen generator and hydrogen combustor rank in the top two of all components. Sensitivity analysis indicates that the outlet temperature of hydrogen combustor and specific energy consumption of water electrolysis hydrogen generator are the crucial influencing factor of system performance. • Propose a hybrid energy storage system based on CAES and WEHG. • Achieve RTE of 65.11%, EXE of 79.23%, and ESD of 5.85 kWh/m3. • A thermodynamic model is built and energy/exergy analysis are conducted. • HC and WEHG are the crucial components influencing the system performance. [ABSTRACT FROM AUTHOR]

With the increasing depletion of conventional energy sources and their detrimental environmental hazards, it is imperative to search for sustainable alternative clean energy sources. In the recent decades, hydrogen has emerged as potential source of clean energy. One of the potential alternatives to achieve the objective is the designing and characterization of materials for hydrogen-storage energy applications. In this regard, metal-bearing hydrides are the most promising candidates. For instance, magnesium-bearing hydrides are the focus of current research work owing to high hydrogen capacity of 7.6 wt%. In this paper, we first time report density functional-based quantum theoretical analysis to explore the potential of Mo-doped magnesium hydrides MgH 2 :Mo for optoelectronic and hydrogen-storage applications. For the quantum computations of the required optoelectronics and energy storage properties, we employed all-electron methods within generalized gradient approximation (GGA). Besides applying GGA approximation to account for the electronic correlated effects, we employed the Hubbard potential U (= 4 eV) for onsite repulsive Coulomb force. We predict that 10% doping by weight of Mo into MgH 2 suppresses its insulating band gap of 4.9 eV to semiconducting band gap of order 3.15 eV for spin up and 0.15 eV for spin down. As such the doping of Mo can tune the the bandgap, structural, electronic and optoelectronic properties of MgH 2 considerably for potential applications. • Quantum-computational analysis of MgH 2 :Mo for optoelectronic & hydrogen-energy applications. • To account for electronic correlation, GGA + U method is employed. • Band gap of MgH 2 :Mo suppresses to 3.15 eV (0.15 eV) for spin up (down). • Suppression of bandgap & thermodynamic stability may enhance kinetic & hydrogen release efficiency. • MgH 2 shows larger hydrogen-storage capacity (7.98%) than MgH 2 :Mo (1.778%). [ABSTRACT FROM AUTHOR]

Solar-hydrogen energy systems for spacecraft reliably provide energy for carrying out various kinds of unscheduled work on board and for eliminating emergency situations. Surplus energy is constantly accumulated on board in the form of the chemical energy of cryogenic hydrogen. The article presents too the result of the development of a solar-hydrogen power supply system for spacecraft, the onboard network of which provides slow and fast processes. The paper presents too pulsed and continuous models of voltage converters of the electrical power system of automatic spacecraft. It is proved on the simulation basis that the deviation of frequency characteristics of continuous models from pulse ones is insignificant (not more than 2%), while the use of continuous models to study both frequency and time characteristics of the converter allows us to reduce the simulation time tenfold. [ABSTRACT FROM AUTHOR]

Energy storage technology provides efficient energy management in renewable driven power system. The long duration time-scale fluctuation in unbalance power becomes more obvious and prominent with the elevated renewable penetration level. However, this issue is not widely considered in current energy storage system. In this paper, a green hydrogen-electric coupled energy storage system based on hydrogen-fueled compressed air energy storage (CAES) and power-to-gas-to-power (PtGtP) device is proposed. The hydrogen-based PtGtP device, including proton exchange membrane fuel cell (PEMFC) and PEM electrolzyer, is employed to smooth out the long duration time-scale fluctuation. Whereas, the hydrogen-fueled CAES is used to settle the remaining time-scale fluctuations. Moreover, the coupled feature is reflected by the hydrogen medium. The hydrogen only generates in PtGtP device, but consumes in both PtGtP device and hydrogen-fueled CAES. The performance assessment by considering the actual operation constraints is conducted based on historical data from real world. The simulated results show that the proposed system can provide an effective and flexible power management in the high share renewable power system. The loss of power supply probability (LPSP) is 5.40%, which is higher than that of any single energy storage system. However, the wind curtailment ratio (WCR) is 8.81%, illustrating an insufficient energy storage capacity. Furthermore, the energy shifting occurs in both several days scale and seasonal scale. This is obvious evidence for function of long duration energy storage (LDES) for the proposed coupled energy storage. • A green hydrogen-electric coupled energy storage system is proposed. • The power-to-gas-to-power device is used to smooth long duration power fluctuation. • The actual operation constraints of system are considered in performance evaluation. • The multiple time-scale fluctuations in unbalance power can be well smoothed. [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]

Hydrogen energy storage systems are expected to play a key role in supporting the net zero energy transition. Although the storage and utilization of hydrogen poses critical risks, current hydrogen energy storage system designs are primarily driven by cost considerations to achieve economic benefits without safety considerations. This paper aims to study the safety of hydrogen storage systems by conducting a quantitative risk assessment to investigate the effect of hydrogen storage systems design parameters such as storage size, mass flow rate, storage pressure and storage temperature. To this end, the quantitative risk assessment procedure, which includes data collection and hazard identification, frequency analysis, consequence analysis and risk analysis, was carried out for the hydrogen storage system presented in a previous study [1]. In the consequence analysis, the Millers model and TNO multi-energy were used to model the jet fire and explosion hazards, respectively. The results show that the storage capacity and pressure have the greatest influence on the hydrogen storage system risk assessment. More significantly, the design parameters may affect the acceptance criteria based on the gaseous hydrogen standard. In certain cases of large storage volume or high storage pressure, risk mitigation measures must be implemented since the risk of the hydrogen storage system is unacceptable in accordance with ISO 19880-1. The study highlights the significance of risk analysis conduction and the importance of considering costs associated with risk mitigation in the design of hydrogen storage system. • A quantitative risk assessment of the hydrogen energy storage system was conducted. • The effects of system parameters (storage capacity, pressure) are thoroughly investigated. • The storage capacity and pressure have the greatest influence on system safety. • A system with a large storage capacity or high pressure poses an unacceptable risk in accordance with standard requirements. [ABSTRACT FROM AUTHOR]

Increased emissions of greenhouse gasses into the atmosphere has adversely been contributing to global warming as a result of burning fossil fuels. Therefore, the energy sectors have been looking into renewable sources such as wind, solar, and hydro energy to make electricity. However, the strongly fluctuating nature of electricity from such energy sources requires a bulk energy storage system to store the excess energy as a buffer and to fulfill the demand constantly. Underground storage is a proven way to store a huge amount of energy (electricity) after converting it into hydrogen as it has higher energy content per unit mass than other gases such as methane and natural gas. This paper reviews the technical aspects and feasibility of the underground storage of hydrogen into depleted hydrocarbon reservoirs, aquifers, and manmade underground cavity (caverns). Mechanisms of underground hydrogen storage (UHS) followed by numerous phenomena such as hydrodynamics, geochemical, physiochemical, bio-chemical, or microbial reactions have been deliberated. Modeling studies have also been incorporated in the literature to assess the feasibility of the process that are also reviewed in this paper. Worldwide ongoing lab study, field study together with potential storage sites have been reported as well. Technical challenges along with proper remedial techniques and economic viability have been briefly discussed. Finally, this paper delivers some feasible strategies for the underground hydrogen storage process, which would be helpful for future research and development of UHS. • Underground hydrogen storage (UHS) is comprehensively reviewed. • Potential storage sites and their characteristics are discussed. • Mechanisms of UHS are discussed. • The challenges and proper recommendations for UHS are deliberated. [ABSTRACT FROM AUTHOR]

The growing share of generation from wind farms is becoming one of the challenges in maintaining the sustainability of electric power systems. System operators approve requirements for the participation of such plants in frequency and power regulation, but they do not contain requirements for specific technologies in the control of wind turbines. There are several methods of frequency and power control, which are implemented by additional control systems, the implementation of underload mode, extraction of hidden inertia, the use of energy storage devices, etc. Each of these methods has both advantages and disadvantages. In this paper we consider the combined coordinated control of type 3 wind turbines using kinetic energy and energy from hydrogen storage to provide the best frequency response in order to minimize the negative factors. A digital-analog-physical model of type 3 wind turbine is used as a model, which allows to reproduce the whole range of transients most accurately and avoid the limitations of strictly numerical simulation. [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]

This paper presents a two-layer framework for improving the resilience of a 118-bus active distribution network consisting of four microgrids, which includes hybrid storage systems, electric buses (EBs), and the direct load control (DLC) program. In the proposed model, the uncertainties of RESs generation, demand, and EBs' mobility are considered, and the robust optimization approach is used to tackle them. In the first layer, the planning of each microgrid is done separately and the energy purchase/sale request is sent to the control center. Then in the second layer, the control center performs the planning of the main network according to the requested program of the microgrids. Note that in this layer, the control center is able to rearrange the distribution feeder and send EBs to vital points of the network. Finally, the validity of the proposed model is evaluated through the implementation on seven case studies and the results show that the presence of hydrogen and electrical storage devices reduces forced load shedding (FLS) by 45.03% and 12.19%, respectively, during emergency situations. In addition, the results indicate that robust planning and the use of EBs for network recovery increase the resilience index by 3.35% and 3.98%, respectively. • Developing a decentralized robust framework for microgrid resilience enhancement. • Providing a two-layer model to guarantee the privacy of microgrids. • Increasing system resilience by electrical and hydrogen storage systems. • Improving system resilience by deploying EBs to vital nodes of the network. • Increasing resilience index through DFR and DLC. [ABSTRACT FROM AUTHOR]

China is ambitiously moving towards "carbon emission peak" and "carbon neutral" targets, and the power sector is in the vanguard. The coordination of power and hydrogen energy storage (HES) can improve energy utilization rate, promoting the deep decarbonization of power industry and realizing energy cascade utilization. However, limited by technology, cost, environment, society and other factors there are few application projects. Identifying major barriers and eliminating unimportant factors can make problem solving more efficient. Decision-making trial and evaluation laboratory (DEMATEL) combined with interpretative structural modeling (ISM) method is innovatively used to establish a barrier analysis framework for HES applied in multiple power scenarios. This method can show the direction and degree of the impact relationship between barriers and determine key ones, which is conducive to presenting targeted and effective solutions. Additionally, the interval type-2 fuzzy set (IT2FS) is introduced to reduce the distortion of evaluation information and ensure the rationality of analysis. Specifically, a comprehensive barrier system taking into account both commonalities and characteristics is established firstly. For different decision considerations, four typical power scenarios are screened to better illustrate how critical barriers play different roles in different scenarios. Then, the proposed analytical framework is applied to identify the key barriers in each scenario and find out the interlinking relationship among the barriers. The results suggest that technical barriers tend to dominate the fundamental barriers. Among that, immature hydrogen storage and transportation technology is a prevalent and fundamental barrier. Besides, high initial investment cost and high P2X conversion costs are crucial reasons that prevent relevant investors from entering the market. And inadequate policy has led to a poor environment for HES development. It's worth noting that, other key barriers focused on each scenario are not the same, and also are discussed in detail in this study. Finally, comprehensive solutions and policy suggestions to eliminate or reduce the barriers are presented. • This paper focuses on promoting hydrogen energy storage application in power field. • 14 barriers from economic, technological, political, environment & social aspects. • Analyze barrier relationships in different scenarios for different considerations. • Fuzzy-ISM-DEMATEL method is applied to analyze barriers system. • Comprehensive policy suggestions are proposed based on analysis results. [ABSTRACT FROM AUTHOR]

In recent years, renewable energy sources (RESs) have attracted substantial attention due to carbon-free and cost-effective advantages that have made them one of the main sources of energy generation in the modern structure of the power grid. This paper proposes the stochastic day-ahead scheduling model for optimal energy management of renewable-based microgrids. In this paper, each microgrid is equipped with 100% RESs including the PV system and wind turbine for full pollutant-free energy generation while the hydrogen energy storage (HES) system is used for alleviating the intermittences of the RESs aiming to dynamically balance the energy during a day. To model the fluctuations such as day-ahead market price in the microgrids, the autoregressive integrated moving average and fast forward selection methods are exerted for scenario production and reduction, respectively. Transactive energy as a sustainable and reliable technique is considered for controlling and coordinating energy sharing among the microgrids and the energy network for dynamic energy balancing in the deregulated environment. For energy management in the demand-side, the price and load response schemes are presented, aiming to revise the consumers' patterns in energy consumption in line with balancing energy and minimizing the microgrids' energy cost. The effectiveness of the suggested model is validated using the modified IEEE 24-bus case study. The realistic modeling of the system based on the proposed model has led to an 8.51% increment in energy cost. • Transactive energy technology is used for managing energy trading between microgrids. • Microgrids with 100% RESs are intended for fully clean energy production. • Hydrogen energy storage system is used for alleviating the fluctuations of the RESs. • A stochastic day-ahead scheduling model is proposed using ARIMA and FFS methods. • The load and price response services are employed for demand-side energy management. [ABSTRACT FROM AUTHOR]

Green hydrogen finds its vital role in bridging the intermittent supplied renewable energy and fossil fuel infrastructure in a broad energy transition context. The bottleneck still lies in hydrogen's low volumetric energy density, prohibiting long-distance, large-scale, and cost-effective transportation. As a promising hydrogen carrier, ammonia possesses mature production, storage, transportation, and distribution supply chains. These advantages of ammonia enabled the possibility of transforming the renewable hydrogen at a minimum initial cost. This paper investigates the technological and economic feasibility of green ammonia utilization in the Solid Oxide Cells for power generation and energy storage. The result shows that the cost of Ammonia induced energy (183.75 US$/MWh) is significantly higher than that of natural gas power plants (81.77 US$/MWh). The main contributor is the fuel cost. In the optimum case, with fuel costs substantially dropping, the conceptual plant can be highly feasible, and the generated energy (97.40 USS$/MWh) is comparable to the conventional power plant. • The low volumetric energy density of hydrogen remains a challenge for long-distance, large-scale transportation. • Ammonia is one of the most promising hydrogen carriers to tackle the hydrogen transportation issue. • The economics of ammonia as a fuel utilized in reversible Solid-Oxide-Cell is investigated. • The SOC energy costs reached 183.75 US$/MWh and 97.40 US$/MWh in the corresponding cases. • Long lifespan and high utilization are critical to the commercialization of cutting-edge technology. [ABSTRACT FROM AUTHOR]

The world is experiencing unprecedented development in the clean energy sector in residential and industrial applications. This paper provides a case study assessing different scenarios of greenizing the electrical energy demand in El-Mostakbal city in Egypt. Three scenarios are studied with consideration of a photovoltaic (PV) system integrated with the grid-connected city with different integrated system configurations. The scenarios for the grid-connected city are scenario-I: only PV, scenario-II: PV with batteries for electricity storage along with grid electricity, and scenario-III: PV with hydrogen production, storage, and utilization for covering the electric demand along with grid electricity, these scenarios are assessed technoeconomically, and the results show an optimized case where the electricity demand of the city can be met with 64.3% produced from solar energy, at $71.7 M of the net present cost. • Energy demand is evaluated using different proposed green scenarios that are assessed techno-economically. • Electricity demand of the city can be met with 64.3% produced from solar energy. • The cost of energy generation for scenario-I is found to be $0.0512 per kWh. [ABSTRACT FROM AUTHOR]

The Philippines is exploring different alternative sources of energy to make the country less dependent on imported fossil fuels and to reduce significantly the country's CO 2 emissions. Given the abundance of renewable energy potential in the country, green hydrogen from renewables is a promising fuel because it can be utilized as an energy carrier and can provide a source of clean and sustainable energy with no emissions. This paper aims to review the prospects and challenges for the potential use of green hydrogen in several production and utilization pathways in the Philippines. The study identified green hydrogen production routes from available renewable energy sources in the country, including geothermal, hydropower, wind, solar, biomass, and ocean. Opportunities for several utilization pathways include transportation, industry, utility, and energy storage. From the analysis, this study proposes a roadmap for a green hydrogen economy in the country by 2050, divided into three phases: I–green hydrogen as industrial feedstock, II–green hydrogen as fuel cell technology, and III–commercialization of green hydrogen. On the other hand, the analysis identified several challenges, including technical, economic, and social aspects, as well as the corresponding policy implications for the realization of a green hydrogen economy that can be applied in the Philippines and other developing countries. • A green hydrogen economy could be feasible in the Philippines. • Renewable energy potential from geothermal, hydropower, wind, solar, biomass, and ocean for green hydrogen production. • Utilization pathways for transport, industry, utility, and energy storage. • The hydrogen economy faces challenges from technical, economic, and social perspectives. • Green hydrogen economy can be achieved by transforming the energy and other sectors to 100% renewables. [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]

With the increasing proportion of renewable energy (mainly wind power and photovoltaic) connected to the grid, the fluctuation of renewable energy power brings great challenges to the safe and reliable operation of power grid. As a clean, low-carbon secondary energy, hydrogen energy is applied in renewable energy (mainly wind power and photovoltaic) grid-connected power smoothing, which opens up a new way of coupling hydrogen storage energy with renewable energy. This paper focuses on the optimization of capacity of electrolyzers and fuel cells and the analysis of system economy in the process of power output smoothing of wind/photovoltaic coupled hydrogen energy grid-connected system. Based on the complementary characteristics of particle swarm optimization (PSO) and chemical reaction optimization algorithm (CROA), a particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) are proposed. Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are constrained by wind power fluctuation, and considering environmental benefits, government subsidies and time value of funds, the objective function and its constraints are established. According to the simulation analysis, by comparing the calculated results with PSO and CROA, it shows that PSO-CROA effectively evaluates the economy of the system, and optimizes the optimal capacity of the electrolyzers and fuel cells. The conclusion of this paper is of great significance for the application of hydrogen energy storage in the evaluation of power smoothness and economy of renewable energy grid connection and the calculation of economic allocation of hydrogen energy storage capacity. • The particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) is proposed. • Based on PSO-CROA, the techno-economic of coupled renewable energy and hydrogen system is analyzed. • Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are optimized. • PSO-CROA effectively evaluates the economy of system and the optimal capacity of the electrolyzers and fuel cells. [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]

The potential role of hydrogen as a tool for the decarbonization of the energy sector is widely recognized. In this paper, a comprehensive analysis of the marginal utility of increasing the hydrogen penetration on the energy and environmental performances of a multi-energy system is developed to assess its potential. A distributed energy system satisfying the energy requirements for an existing building is chosen as test case, assumed as representative of a wide set of applications. Starting from real energy consumption profiles, representative scenarios and optimized design configurations are defined using a methodology that takes into account uncertainties both in demand and renewable production profiles and in techno-economic parameters assumptions. For each multi energy system configuration, an optimal dispatch control strategy is achieved through a mixed-integer linear programming method to maximize the building self-independence from the grid. Results show how an increase of hydrogen technologies penetration allows a reduction of the specific carbon footprint of the system down to 100 grCO 2 /kWh while increasing the system resilience up to 85%. Detailed information about the marginal effect of H 2 technologies on resilience, carbon footprint, and fossil energy savings are presented and can be used for extensions to similar applications. • Resilience up to 85% is achieved through hydrogen integrated multi-energy system. • Specific carbon footprint is reduced up to 100grCO 2 /kWh. • Uncertainties are accounted through a coupled clustering-Montecarlo approach. • Hydrogen seasonal storage is crucial for decarbonization of the energy system. [ABSTRACT FROM AUTHOR]

This paper is a critical review of selected real-world energy storage systems based on hydrogen, ranging from lab-scale systems to full-scale systems in continuous operation. 15 projects are presented with a critical overview of their concept and performance. A review of research related to power electronics, control systems and energy management strategies has been added to integrate the findings with outlooks usually described in separate literature. Results show that while hydrogen energy storage systems are technically feasible, they still require large cost reductions to become commercially attractive. A challenge that affects the cost per unit of energy is the low energy efficiency of some of the system components in real-world operating conditions. Due to losses in the conversion and storage processes, hydrogen energy storage systems lose anywhere between 60 and 85% of the incoming electricity with current technology. However, there are currently very few alternatives for long-term storage of electricity in power systems so the interest in hydrogen for this application remains high from both industry and academia. Additionally, it is expected that the share of intermittent renewable energy in power systems will increase in the coming decades. This could lead to technology development and cost reductions within hydrogen technology if this technology is needed to store excess renewable energy. Results from the reviewed projects indicate that the best solution from a technical viewpoint consists in hybrid systems where hydrogen is combined with short-term energy storage technologies like batteries and supercapacitors. In these hybrid systems the advantages with each storage technology can be fully exploited to maximize efficiency if the system is specifically tailored to the given situation. The disadvantage is that this will obviously increase the complexity and total cost of the energy system. Therefore, control systems and energy management strategies are important factors to achieve optimal results, both in terms of efficiency and cost. By considering the reviewed projects and evaluating operation modes and control systems, new hybrid energy systems could be tailored to fit each situation and to reduce energy losses. • Review of 15 projects that use hydrogen as energy storage in a power system. • Hydrogen is one of very few alternatives for long-term electricity storage. • Hydrogen storage should in most cases be combined with battery storage. • Power-to-gas-to-power for hydrogen still has a low energy efficiency (15–40%). • Intermittent in-flow of energy and high costs are big challenges for these systems. [ABSTRACT FROM AUTHOR]

The development and application of hydrogen energy in power generation, automobiles, and energy storage industries are expected to effectively solve the problems of energy waste and pollution. However, because of the inherent characteristics of hydrogen, it is difficult to maintain high safety during production, transportation, storage, and utilization. Therefore, to ensure the safe and reliable utilization of hydrogen, its characteristics relevant to leakage and diffusion, ignition, and explosion must be analyzed. Through an analysis of literature, in combination with our practical survey analysis, this paper reviews the key issues concerning hydrogen safety, including hydrogen incident investigation, hydrogen leakage and diffusion, hydrogen ignition, and explosion. • Key problems and challenges regarding safety of hydrogen utilization are reviewed. • A total of 120 hydrogen incidents are examined. • Subsonic and under-expanded jet formation, and their modeling methods, are studied. • Several hydrogen self-ignition hypothetical theories are analyzed and summarized. • Deflagration-to-detonation transition and its interfering factor are described. [ABSTRACT FROM AUTHOR]

Mountain huts, as special, stand-alone, micro-grid systems, are not connected to a power grid and represent a burden on the environment. The micro-grid has to be flexible to cover daily and seasonal fluctuations. Heat and electricity are usually generated with fossil fuels due to the simple on-off operation. By introducing renewable energy sources (RESs), the generation of energy could be more sustainable, but the generation and consumption must be balanced. The paper describes the integration of a hydrogen-storage system (HSS) and a battery-storage system (BattS) in a mountain hut. The HSS involves a proton-exchange-membrane water electrolyser (PEMWE), a hydrogen storage tank (H 2 tank), a PEM fuel cell (PEMFC) and a BattS consisting of lead-acid batteries. Eight micro-grid configurations were modelled using HOMER and evaluated from the technical, environmental and economic points of view. A life-cycle assessment analysis was made from the cradle to the gate. The micro-grid configurations with the HSS achieve, on average, a more than 70% decrease in the environmental impacts in comparison to the state of play at the beginning, but require a larger investment. Comparing the HSS with the BattS as a seasonal energy storage, the hydrogen-based technology had advantages for all of the assessed criteria. • Eight configurations of mountain-hut stand-alone energy system are studied. • A novel approach using technical, economic and environmental criteria is introduced. • Hydrogen-storage combined with renewable energy sources is the optimal solution. • For seasonal energy storage, hydrogen is more favourable than a battery-storage. [ABSTRACT FROM AUTHOR]

Over the past years, hydrogen has been identified as the most promising carrier of clean energy. In a world that aims to replace fossil fuels to mitigate greenhouse emissions and address other environmental concerns, hydrogen generation technologies have become a main player in the energy mix. Since hydrogen is the main working medium in fuel cells and hydrogen-based energy storage systems, integrating these systems with other renewable energy systems is becoming very feasible. For example, the coupling of wind or solar systems hydrogen fuel cells as secondary energy sources is proven to enhance grid stability and secure the reliable energy supply for all times. The current demand for clean energy is unprecedented, and it seems that hydrogen can meet such demand only when produced and stored in large quantities. This paper presents an overview of the main hydrogen production and storage technologies, along with their challenges. They are presented to help identify technologies that have sufficient potential for large-scale energy applications that rely on hydrogen. Producing hydrogen from water and fossil fuels and storing it in underground formations are the best large-scale production and storage technologies. However, the local conditions of a specific region play a key role in determining the most suited production and storage methods, and there might be a need to combine multiple strategies together to allow a significant large-scale production and storage of hydrogen. • Large-scale production and storage of hydrogen are presented. • Renewable hydrogen is summarized. • Non-renewable hydrogen is discussed. • Natural underground hydrogen storage is presented. [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]

Intermittency is one of the main obstacles that inhibit the wide adoption of the renewable energy in the power sector. Small-scale fluctuations can be tackled by short-term energy storage system, whereas long-term or seasonal intermittencies rely on large-scale energy management solutions. Besides the supply and demand mismatch in temporal domain, renewable energy sources are usually far away from consumption points. To connect the energy sources to the demand cost-effectively, cable transmission is usually the default option, and considering the long distance, other emerging energy carriers such as hydrogen could be a feasible option. However, there is handful studies on the quantitative evaluation of the long-distance energy transmission cost. This paper investigated the economic feasibility of renewable energy transmission via routes of power cable and gas pipeline. In the direct power transmission case, renewable energy is transmitted via HVDC cable and then converted to hydrogen for convenient storage. The alternative case converts renewable energy into hydrogen at the source and transports the hydrogen in the gas pipeline to consumers. Existing data available from public domain are used for cost estimation. Results show that the improvements of capacity factor and transmission scale are the most cost-effective approach to make the renewable hydrogen economically viable. At 4000 km of transmission distance, renewable hydrogen LCOE of 7 US$/kg and 9 US$/kg are achievable for the corresponding optimum cases, respectively. • The Power-to-Gas technology converts renewable energy into hydrogen for low-cost transmission. • Renewable power fluctuations could be mitigated spatially with power cables and gas pipelines. • The levelized cost of the cable/pipeline transmitted hydrogen are evaluated. • The renewable hydrogen are most sensitive to the capacity factor and transmission capacity. [ABSTRACT FROM AUTHOR]

Spain has presented a plan (known as PNIEC) to reduce conventional energy sources (shutting down 16 GW) and to increase the use of renewable sources (incorporating 65 GW). This generation portfolio leads to a situation in which there will be a surplus of electrical energy in spring and summer, which will be lacking in autumn and winter. The plan sets a target on batteries, but insufficient to manage more than 10 TWh over 6 months. This paper proposes the deployment of electrolysers to produce hydrogen with the surplus energy, using the already existing Spanish natural gas network to store it. The resulting gas (up to 15% blend of hydrogen in natural gas) could be used subsequently in turbines to alleviate the energy deficit. With this strategy, up to 7.27 TWh of the surplus renewable energy could be reused, and 2.54 million tons of CO2 equivalent would be avoided yearly. • Energy network management with more than 50% of renewable sources is feasible. • The use of the natural gas network for H 2 storage allows seasonal energy management. • H 2 as a means of seasonal energy storage would complement the use of batteries. • Renewable H 2 would avoid the need to import a significant amount of natural gas. • Renewable hydrogen can be used as alternative fuel or in industrial applications. [ABSTRACT FROM AUTHOR]

This paper applies a mixed integer linear programming model developed in GAMS to simulate the integration of Power-to-Gas infrastructure into an industrial manufacturer's energy system subject to the existing thermal and electrical energy demands, as well as a third hydrogen energy profile. This work is novel in that it assesses the challenges and economic incentives available to make feasible the installation of a hydrogen-based energy storage systems within the Province of Ontario from a techno-economic, policy and environmental perspectives. The energy hub analyzed in this work uses electricity from the power grid and solar PVs to meet the manufacturer's demands, while converting the excess to hydrogen gas, which is used across an array of pathways to generate revenue. ThisThis includes a blend ofof hydrogen for fuel cell vehicles (FCVs), hydrogen for forklifts, and the direct injection of hydrogen into the facility's natural gas, adding renewable content to the heating, and manufacturing processes. Our primary objective was to implement a safe design that minimizes capital and operating costs, resulting in a favorable business case for producing hydrogen, and providing ancillary grid services. However, Power-to-Gas creates a net-emission reduction that can be used not only to sell emission allowances in the provincial carboncarbon tax program for up to $30/t-CO 2eq but to assist the Company in achieving their strategic emission reduction targets. Installation of the selected Power-to-Gas system would require a total capital investment of $2,620,448 with the electrolyzers and solar panels accounting for 41% and 17% of the capital costs, respectively. The compressors will account for most of the operating costs which total $237,653 annually. Within the energy hub, 76,073 kg-H 2 has been produced per year for end-use applications. A sensitivity analysis was performed by varying both hydrogen and carbon credit price which predicted a potentialpotential CO 2 offset of 2359.7 tonne/yr with a payback period of as little as 2.8 years. • MILP model optimizing an industrial energy system incorporating new P2G technology. • Costing of a P2G installation and analysis of ROI based on hydrogen revenue streams. • A sensitivity analysis based on environmental and regulatory policy changes. • Determines emission offsets resulting from the use of fuel cell vehicles. • A policy review of the challenges of implementing P2G in Ontario. [ABSTRACT FROM AUTHOR]

One of the key challenges that still facing the adoption of renewable energy systems is having a powerful energy storage system (ESS) that can store energy at peak production periods and return it back when the demand exceeds the supply. In this paper, we discuss the costs associated with storing excess energy from power grids in the form of hydrogen using proton exchange membrane (PEM) reversible fuel cells (RFC). The PEM-RFC system is designed to have dual functions: (1) to use electricity from the wholesale electricity market when the wholesale price reaches low competitive values, use it to produce hydrogen and then convert it back to electricity when the prices are competitive, and (2) to produce hydrogen at low costs to be used in other applications such as a fuel for fuel cell electric vehicles. The main goal of the model is to minimize the levelized cost of energy storage (LCOS), thus the LCOS is used as the key measure for evaluating this economic point. LCOS in many regions in United States can reach competitive costs, for example lowest LCOS can reach 16.4¢/kWh in Illinois (MISO trading hub) when the threshold wholesale electricity price is set at $25/MWh, and 19.9¢/kWh in Texas (ERCOT trading hub) at threshold price of $20/MWh. Similarly, the levelized cost of hydrogen production shows that hydrogen can be produced at very competitive costs, for example the levelized cost of hydrogen production can reach $2.54/kg-H 2 when using electricity from MISO hub. This value is close to the target set by the U.S. Department of Energy. Levelized cost of energy storage (LCOS) curves for several regions in the United States. Image 1 • A model to calculate the levelized cost of energy storage for reversible fuel cells. • RFC system as energy storage system can increase the resiliency of the power grids. • RFC can be designed to store electricity and produce hydrogen for other uses. • Roundtrip efficiency and capital cost are key factors that shape the LCOS in RFC. [ABSTRACT FROM AUTHOR]

This paper presents an integrated Fuzzy Analytical Hierarchy Process (f AHP) and Weighted Fuzzy Axiomatic Design (wf AD) methodology for a strategic level problem of hydrogen energy storage (HES) method selection for Turkey. Considering alternatives of tank, metal hydride and chemical storage, we design our decision problem with respect to five assessment criteria as weight, capacity, storage loss and leak, reliability, and total system cost. In the solution methodology, we first implement f AHP to determine criteria weights by incorporating linguistic judgement and vague information. Next, we define functional requirements and design parameters for the selection problem and use wf AD to compare alternatives. After implementing the proposed integrated approach, we perform additional sensitivity analysis experiments to test the robustness of the solution with respect to changes in functional requirements. • We consider a hydrogen energy storage method selection problem for Turkey. • We incorporate three alternatives as tank, metal hydride, and chemical. • We use fuzzy analytical hierarchy process to determine criteria weights. • We use weighted fuzzy axiomatic design to select the most appropriate alternative. • Our results reveal that metal hydride is the most appropriate solution. [ABSTRACT FROM AUTHOR]

Power to hydrogen is a promising solution for storing variable Renewable Energy (RE) to achieve a 100% renewable and sustainable hydrogen economy. The hydrogen-based energy system (energy to hydrogen to energy) comprises four main stages; production, storage, safety and utilisation. The hydrogen-based energy system is presented as four corners (stages) of a square shaped integrated whole to demonstrate the interconnection and interdependency of these main stages. The hydrogen production pathway and specific technology selection are dependent on the type of energy and feedstock available as well as the end-use purity required. Hence, purification technologies are included in the production pathways for system integration, energy storage, utilisation or RE export. Hydrogen production pathways and associated technologies are reviewed in this paper for their interconnection and interdependence on the other corners of the hydrogen square. Despite hydrogen being zero-carbon-emission energy at the end-use point, it depends on the cleanness of the production pathway and the energy used to produce it. Thus, the guarantee of hydrogen origin is essential to consider hydrogen as clean energy. An innovative model is introduced as a hydrogen cleanness index coding for further investigation and development. Image 1 • Innovative hydrogen cycle model proposed of a square-shaped Hydrogen Square (HydS). • Innovative HPP categorising model proposed to describe the H 2 production pathways.. • The cost of the hydrogen purification must be added to the hydrogen cycle feasibility. • The guarantee of hydrogen origin is essential to ensure its energy cleanness. • An innovative hydrogen cleanness index model has been introduced. [ABSTRACT FROM AUTHOR]