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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]

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

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 presents a hybrid Fuel Cell-based Power System (FCPS) consisting of fuel cell and hybrid Energy Storage Systems (ESSs), including a battery with high energy density and supercapacitor with high power density to overcome the sudden load demand change and improving the reliability of the delivered power. Any hybrid power system needs Energy Management Strategies (EMS) to balance the power between the different energy sources. In this paper, a comparative analysis of three energy management strategies, including the state machine control method, the classical PI control method and equivalent consumption minimization strategy (ECMS) is performed. The paper's main objective is enhancing the DC-bus voltage profile of a hybrid fuel cell/battery/supercapacitor power system equipped with the developed under-mentioned EMS by using a hybrid modified optimization technique that combines Harris Hawks optimization (HHO) and Sine Cosine Algorithm (SCA). The new hybrid HHO-SCA is employed to determine the optimal control parameters of the DC-bus voltage controller, which significantly assists in enhancing the DC-bus voltage profile as well as the performance of the applicable ESS in terms of improving efficiency and SoC. The effectiveness of the suggested control schemes is simulated using MATLAB/SIMULINK software. The simulation results confirmed that the proposed HHO-SCA is superior and efficient in improving the DC-bus voltage. • A comparative analysis of three energy management strategies is presented. • New hybrid optimization technique is developed. • Optimal tuning for the control parameters of the DC-bus voltage controller. • Enhancing the DC-bus voltage profile and some performance criteria are conducted. [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]

This paper presents an improved direct rotor field oriented control of seven phase induction motor in hybrid electric vehicle (HEV) system. The dynamic model of the machine shows that non-sequential currents producing no torque appear and degrade the quality of currents. Further, the fuzzy logic controller is proposed to filter non-sequential components and improves the quality energy. Hybridization of the electric vehicle by a fuel cell (HEV) and an auxiliary energy source has the advantage of improving the dynamic response and efficiency of the system. Indeed, an ultra-capacitor (UC) used as a means of energy storage to enable the lower dynamic FC when changes in power fast and recovers braking energy as well as absorption of immanent disturbances of the static converters. Improving the quality of energy demand can improve not only the lifetime of the actuator but also the onboard sources. One of the results of the reduction of interference in the system induces to the reduction of mechanical vibrations, which generates quieter systems, which is an advantage for these urban transport applications. In this paper, the modeling of the different parts of the multi-physical system that represent hybrid vehicle are presented. The performance of the aimed system is analysed under different acting conditions. [ABSTRACT FROM AUTHOR]

Due to the lack of distribution resources and increasing demand in the daily market, the use of renewable resources is increasing. But renewable sources and market prices are uncertain behavior and cause economic problems. This paper introduces a novel market participation model include wind turbine, photovoltaic, fuel cell integrated with a novel hybrid TES energy storage system (3 in 1 concept) to minimize cost and improve load demand reliability. Also, to solve he mentioned problem a novel forecasting method are proposed. This model is a new multi artificial neural network based on the complete ensemble empirical mode decomposition which is coupled with Tanh function and using RMSE, MAPE and NMAE method the error rate of the proposed method is calculated. By using this method, the forecasting accuracy is improved and also with a novel energy storage the economic issue and market reliability are improved. Also, using the stochastic model the uncertainty system's behavior are modeled to obtain an accurate results of market participation and increase demand supply. Finally, a testing system includes wind turbine/photovoltaic/fuel cell/storage system and demand response are used to prove the superiority of the proposed model in comparison to other models. • A new hybrid 3 in 1 TES storage is used to maximize the operational energy density. • A novel method integrated with fuel cells/wind turbines/solar cells is proposed. • An accurate forecasting method based on (CEEMD) and (MANN) is presented. • Considering uncertain parameters as wind speed, solar radiation, and market price. • DRP is implemented to manage energy consumption. [ABSTRACT FROM AUTHOR]

The reliance on fossil fuels is one of the most challenging problems that need to be dealt with vigorously in recent times. This is because using them is not sustainable and leads to serious environmental issues, such as: air pollution and global warming. This condition affects economic security and development. An alternative to fossil fuel is highly possible which will be more environmentally friendly, sustainable and efficient as well. Among all the different technologies associated with renewable energy, fuel cell technologies represent one of the most promising technological advancement to curb the situation. In this paper, an overview of the technology and its advantages and disadvantages compared with competitive technologies was revealed. The application of different fuel cell types in the stationary and portable sectors was covered. Furthermore, recent challenges and promising developments of current fuel cell technologies in different studied applications were reviewed. Some possible solutions to the challenges were named in this paper for both the portable and stationary fuel cell applications. The paper further seeks to expose the world to the current progress made in the fuel cell industry up to date and possible areas that needs intensified research and modifications to make the fuel cell industry more vibrant and buoyant. [ABSTRACT FROM AUTHOR]

In this paper, development and simulation of photovoltaic (PV), solid oxide fuel cell (SOFC) and battery energy storage system (BESS) based microgrid is presented. The microgrid system is operating in autonomous mode to serve the loads. To effectively control the microgrid voltage and frequency and to achieve smoother power flow control between the generation and consumption, voltage–frequency (V/F) control based on fuzzy logic controller (FLC) is proposed in this paper. Even though when there are sudden load variations in the system and fluctuations in PV output power, the microgrid voltage and frequency is effectively maintained within the limits by the proposed FLC. The main function of the BESS is to absorb/supply the excess/deficit power from the PV system and to keep the dc-link voltage of the voltage source converter (VSC) constant. SOFC is used as a backup generator and it is controlled to generate its rated power when the state of charge (SOC) of the BESS reaches its lower limit. The PV, SOFC and BESS are connected to a common dc bus through dc–dc power electronic converters. A three phase VSC is used to convert the dc to ac and to supply various ac loads. The PV, BESS and SOFC based microgrid system is simulated using Matlab/Simulink. To show the effectiveness of the proposed FLC over the conventional proportional-integral (PI) controller, the same system is simulated using PI controller and the necessary results are compared. [ABSTRACT FROM AUTHOR]

Utilization of Natural gas and Hydrogen to support current and future building energy needs to offset the total electric demand while improving the grid resiliency and energy efficiency was investigated. Demand side energy management will play an important role in efficiently managing the available energy resources. Performance assessment of different power generation and energy management configurations is presented in this paper. Development of solutions in addressing grid resiliency by providing the ability to design suitable configurations for meeting individual building energy needs is discussed. Primary movers (PM) such as internal combustion engines (ICE) and fuel cells (FC) along with small scale auxiliary renewable energy source such as photovoltaics (PV) were considered. Key attributes of total carbon foot-print, life cycle costs including capital and operational expenditure, electric grid offset or peak shaving capability, thermal energy availability and its further potential to offset total electric demand, and primary energy intensity are analyzed and discussed in detail. Image 1 • Grid resiliency and higher energy η are possible using Hydrogen carriers (e.g. NG). • It is possible to lower the primary energy consumption by > 35%. • CO 2 emissions can be lowered by > 30% while improving resiliency. • Thermal energy utilization can offset the total grid demand by > 60%. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study of a standalone hybrid microgrid system. The latter is dedicated to remote area applications. The system is a compound that utilizes renewable sources that are Wind Generator (WG), Solar Array (SA), Fuel Cell (FC) and Energy Storage System (ESS) using a battery. The power electronic converters play a very important role in the system; they optimize the control and energy management techniques of the various sources. For wind and solar subsystem, the speed and Single Input Fuzzy Logic (SIFL) controllers are used respectively to harvest the maximum power point tracking (MPPT). To maintain a balance of energy in the hybrid system, an energy management strategy based on the battery state of charge (SOC) has been developed and implemented experimentally. The AC output voltage regulation was achieved using a Proportional Integral (PI) controller to supply a resistive load with constant amplitude and frequency. According to the obtained performances, it was concluded that the proposed system is very promising for potential applications in hybrid renewable energy management systems. • Realization of an experimental wind turbine emulator based on an induction motor. • Implementation of the Single Input Fuzzy Logic MPPT controller for PV Emulator. • DC bus voltage regulation based on the Fractional Order PID controller. • Power management strategy for a hybrid system based on the battery state of charge. [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]

Abstract: Nowadays, renewable power system solutions are widely investigated for residential applications. Grid-connected systems including energy storage elements are designed. Advanced research is actually focused on improving the reliability and energy density of renewable systems reducing the whole utility cost. Source and load modeling, power architectures and algorithms are only a few topics to be addressed. Designers have to carefully deal with each subtopic prior to design efficient renewable energy systems. In the literature, each topic is separately discussed and the lack of a unique reference guide is clear to power electronics designers. In this paper, each design step including source and load modeling, hybrid supply architectures and power algorithms, is carefully addressed. A review of existing solutions is presented. The correlation between each topic is deeply analyzed. Guidelines for system design are given. This paper can be referenced as a detailed review of renewable energy system design issues and solutions. [Copyright &y& Elsevier]

Abstract: In this paper the powertrain of a zero emission vehicle powered by hydrogen has been designed with an innovative approach via reverse engineering. The use of a zero environmental impact vehicles is particularly stringent in urban area where high air pollutant concentrations could be reached. In particular, in this paper, the use of fuel cell vehicles plus ultracapacitors has been considered to minimize the TTW (Tank to Wheels) global efficiency in comparison with the conventional vehicles powered by ICE. A zero emissions city-car is designed by optimization of the components (in particular the energy storage) in order to minimize both its weight and its bulk with particular reference to the functions (passenger vehicles, minibus, freight distribution), the areas where the vehicle is driven (characteristic drive cycles, traffic) and the users (different driving style). In particular the design discussed in this paper was carried out through a process of reverse engineering. The energy needs, in fact, were calculated starting from real drive cycles obtained during an on-board data acquisition campaign carried out in Rome urban area. In this paper the powertrain is designed starting from the acquisition of real drive cycles obtained during acquisitions campaign in an urban area. The data collected by the on-board acquisitions systems has been used to evaluate the power required by the wheels as a function of time in a generic urban drive cycle and the energy needs of an urban vehicle. Thus, the analysis performed takes into account not only global energy consumption, but also the power needs that are affected by both the congested traffic conditions and the driving style. [Copyright &y& Elsevier]

Abstract: Depending on growing concerns on energy crises and environmental issues, fuel cell (FC) powered electrical vehicles are favored for possible substitute to conventional internal combustion engine (ICE) based vehicular systems. However, the typical power profile of an automobile motor consisting of transients is not suitable for the use of a sole FC system for vehicle propulsion. This shortcoming could be partly overcome by hybridization. Two potential benefits of combining an FC system with an energy storage unit, ultra-capacitor (UC) has been presented in this study. Firstly, the durability of the FC system could be improved because the additional energy source can fulfill the transient power demand fluctuations. Secondly, the ability of the energy storage source to recover braking energy enhances the fuel economy greatly. An important aspect in designing a hybrid power structure is to find a suitable control strategy that can manage the active power sharing and take advantage of the inherent scalability and robustness benefits of the hybrid system. An integrated procedure for mathematical modeling and power control strategy design for an FC/UC hybrid vehicle is presented in this paper. A fuzzy logic supervisory controller based power management strategy that secures the power balance in hybrid structure, enhances the FC performance and minimizes the power losses is proposed. The main contribution of this paper apart from the previous studies of the authors is the modeling of the complete FC power system with air supply compressor and the integration of the control of the FC system internal dynamics (especially the oxygen excess ratio) into the overall supervisory control structure to maximize the efficiency and durability. To demonstrate the effectiveness of the proposed power management scheme, simulation studies were performed using MATLAB®, Simulink® and SimPowerSystems® environments by integrating the detailed mathematical and electrical models of the hybrid vehicular system. [Copyright &y& Elsevier]

In this paper, two alternative integrated power systems were considered: one based on photovoltaic and hydrogen technology (electrolyzer coupled with a fuel cell), the other based on photovoltaic and batteries. The two systems, designed for off-grid applications, were sized for a photovoltaic energy production in the area of Turin, Italy, to provide 3 kW maximum power, with an average daily consumption of 10.25 kWh. The systems were compared from a technical and economical point of view and a Life Cycle Assessment analysis (LCA) was performed, to identify the main contributors to the environmental impact of the systems. From a commercial point of view, fuel cell and the electrolyzer are niche products, so the hydrogen-based power system results to be more expensive with respect to Li-ion batteries. From the environmental point of view, however, LCA results show the lower burdens of the hydrogen technology. [ABSTRACT FROM AUTHOR]

Fuel cell hybrid construction vehicles (FCHCVs) are an attractive long-term option for the propulsion of CVs. This paper presents an approach for the design and analysis of an FCHCV with supercapacitors as the energy-storage device. The design stage includes determination of the topology of the electrical system, energy flow analysis, and a determination of the energy-storage system. Due to the markedly changing loads, supercapacitors with high specific power and high durability seem the best choice. A control strategy based on Pontryagin's minimum principle is proposed considering hydrogen consumption, the state of charge of the supercapacitors, and fuel cell durability in the cost functions. With the selected design and proposed strategy, we propose a power source sizing methodology, and its economic influence is evaluated for both present and future FCHCVs. This study was performed with a system-level model of an FCHCV in MATLAB environment. Simulation results demonstrate the superiority of the proposed strategy. Optimal power source sizes can be chosen by specific criteria of hydrogen consumption and powertrain cost. FCHCVs will become very attractive, assuming that the related costs are reduced in the future. [ABSTRACT FROM AUTHOR]

In this paper the modeling of a hybrid photovoltaic/fuel cell system is presented. It consists of a photovoltaic generator (PV), a proton exchange membrane fuel cell (PEMFC), and power conditioning units (PCU) to manage the system operation of the hybrid system. When there is an excess of solar generation available, the electrolyzer is turned on to begin producing Hydrogen which is sent to a storage tank. The produced Hydrogen is used by the fuel cell stack which produces electrical energy to supply the DC bus. The global system is modeled and simulated under Matlab/Simulink and results are presented and discussed. [ABSTRACT FROM AUTHOR]

The hybridization of the fuel cell (FC) hybrid electric vehicle (HEV) by an auxiliary energy source has the benefit of improving the system's dynamic response and efficiency. Indeed, an ultra-capacitor (UC) used as an energy storage device to permit the FC lowest dynamics during fast power changes and recovers the braking energy to enhance the HEV autonomy. In FC/UC HEV, an adequate power management approach is one essential objective of the researches in this area. In this paper, an advanced control strategy managing the power distribution among the two energy sources is elaborated using state-flow bloc of Matlab/Simulink. The UC control power is realized indirectly through the DC bus voltage regulation. For the FC power demand, an algorithm with filtering power vibrations is developed. This algorithm, depending on the UC state of charge (SOC) and the vehicle speed to minimize the FC power demand transitions and enhance its life time. The traction power is provided utilizing two five-phase permanent magnetic synchronous machines (PMSM) in each rear wheels of the vehicle to reduce clutter caused by mechanical part. A fault tolerant strategy is added to eliminate all faults appeared in the tractions machines in aims to reduce torque ripples and power vibrations for more stability and length life time of the HEV systems. The models of the HEV and the control strategy are produced employing Matlab/Simulink. Simulation results indicate the desirability of the proposed system and its energy management strategy for HEV. [ABSTRACT FROM AUTHOR]

Abstract: The hybridization of the fuel-cell electric-vehicle (FCEV) by a second energy source has the advantage of improving the system's dynamic response and efficiency. Indeed, an ultra-capacitor (UC) system used as an energy storage device fulfills the FC slowest dynamics during fast power transitions and recovers the braking energy. In FC/UC hybrid vehicles, the search for a suitable power management approach is one of the main objectives. In this paper, an improved control strategy managing the active power distribution between the two energy sources is proposed. The UC reference power is calculated through the DC link voltage regulation. For the FC power demand, an algorithm with five operating modes is developed. This algorithm, depending on the UC state of charge (SOC) and the vehicle speed level, minimizes the FC power demand transitions and therefore ameliorates its durability. The traction power is provided using two permanent magnetic synchronous motor-wheels to free more space in the vehicle. The models of the FC/UC vehicle system parts and the control strategy are developed using MATLAB software. Simulation results show the effectiveness of the proposed energy management strategy. [Copyright &y& Elsevier]

Abstract: HELION, a subsidiary of AREVA in charge of the business unit Hydrogen and energy storage, is deploying for the first time in a French public building, a hydrogen-based energy storage system, the Greenergy Box™. The 50 kWe system is coupled with a photovoltaic farm to ensure up to 45% electrical autonomy and power backup to the building. The safety system and siting measures of the complete hydrogen chain are described. The paper also highlights the work accomplished with Fire Authorities and Public to gain the acceptance of the project and allow the deployment of four other hydrogen-based green buildings. [Copyright &y& Elsevier]

Abstract: A typical working mode for the fuel cell hybrid system is that the fuel cell produces constant power output while the auxiliary storage energy device such as ultracapacitor or battery provides the deviation between the desired power demand and the value of the actual operation. This paper concentrates on the control of the fuel cell flow system. The system which is like an under-actuated mechanical system needs to control two objects (the cathode pressure and the air flow) with one manipulated variable (the set voltage of the air mass flow controller). A SIRMs-based fuzzy inference model is successfully implemented in the system. Online random search optimization algorithm based on Simulink C-S functions is developed to adjust the parameters in the model. By alternative control of the two objects, experimental results demonstrate the realization of the control strategy with one adjustment means. [Copyright &y& Elsevier]

Abstract: In this study, poly(3,4-ethylenedioxythiophene) (PEDOT)-modified graphene composite materials have been shown to exhibit excellent energy storage and conversion properties. Flexible, conducting and porous carbon cloth (CC) and graphene paper (GP)-modified CC (GP/CC) were used as substrates for comparison in all experiments. PEDOT was electrodeposited on these substrates, and their capacitance properties were measured for supercapacitor applications. Furthermore, the adsorption of size-selected Pt colloidal nanoparticles has also been performed using two substrates to form the electrode materials for fuel cell applications. We found that the PEDOT/GP/CC is the excellent flexible electrode material for both supercapacitors and fuel cells. [Copyright &y& Elsevier]

Abstract: This paper presents an economic comparison of fuel cell powered forklifts to various types of battery powered forklifts. The total costs of ownership of each technology is calculated and compared over their economic lifetimes and at varying workloads to determine the economic costs or benefits associated with each technology. The study is novel compared to the previous literature in that all data sources are referenced, it includes a model that is scalable by facility workload, and it includes the economic costs of hydrogen storage and charging infrastructure. Results show that fuel cell forklifts are more expensive to purchase and operate that battery powered forklifts for the types of facilities considered in this analysis. Fast charge forklifts are shown to be economically advantaged at high workloads relative to conventional battery-swapping forklifts. [Copyright &y& Elsevier]

Abstract: In this paper, we present a new route for recycling waste Mg with the production of MgH2 nanofiber, which is a promising candidate for energy storage and conversion used in Li-ion batteries and H2 storing technologies. Highly pure MgH2 nanofibers were successfully manufactured from Mg-alloy swarfs (AM60B and AZ91D) via the hydriding chemical vapor deposition (HCVD) process. The possibility of recycling all types of Mg scraps using the HCVD process was demonstrated, which requires only a pretreatment of obtaining a dried raw material. The HCVD method shows many advantages over other methods in the synthesis of MgH2: it can produce MgH2 at low cost using waste Mg as the raw material, requires less energy, offers a high-purity product, and enables control over the growth of nanosized structures. [Copyright &y& Elsevier]

Abstract: In small hybrid wind systems, excess wind energy is stored for later use during the deficit power generation. Excess wind energy can be stored as hydrogen in a metal hydride storage bed and reused later to generate power using a fuel cell. This paper deals with the discharge dynamics of the coupled fuel cell and metal hydride storage bed during the power extraction. Thermal coupling of the fuel cell and metal hydride bed is also discussed. The waste heat generated in the fuel cell is removed using a water coolant. The exit fuel cell coolant stream is passed through the metal hydride storage bed to supply the necessary heat required for desorption of hydrogen from the bed. This will also lead to a reduction in the load on the radiator. The discharge dynamics and the thermal management of the coupled system are demonstrated through a system simulation model developed in Matlab/Simulink platform. [Copyright &y& Elsevier]

Abstract: The use of intermittent renewable energy sources for power supply to off-grid electricity consumers depends on energy storage technology to guarantee continuous supply. Potential applications of storage-guaranteed systems range from small installations for remote telecoms, water-pumping and single dwellings, to farms and whole communities for whom grid connection is too expensive or otherwise infeasible, to industrial, military and humanitarian uses. In this paper we explore some of the technical issues surrounding the use of hydrogen storage, in conjunction with a PEM electrolyser and PEM fuel cell, to guarantee electricity supply when the energy source is intermittent, most typically solar photovoltaic. We advocate metal-hydride storage and compare its energy density to that of Li-ion battery storage, concluding that a significantly smaller package is possible with metal-hydride storage. A simple approach to match the output of a photovoltaic array to an electrolyser is presented. The properties required for the metal-hydride storage material to interface the electrolyser to the fuel cell are discussed in detail. It is concluded that relatively conventional Mischmetal-based AB5 alloys are suitable for this application. [Copyright &y& Elsevier]

Abstract: PEPITE is a project funded by the French ANR PAN-H research program. This project concerns, among various other tasks, a demonstration of a weather station electricity supply with help of a PV/FC/EL hybrid system located at the CEA center of Cadarache (France). To design a relevant sizing for this demonstration system, a complete sizing tool has been developed via a new numerical optimizing code named ORIENTE. It uses Matlab software based on sequential running time. The demonstration system will be composed of a PV array, a PEM fuel cell system and a PEM electrolyzer, batteries, storage tanks for H2, O2 and H2O, as well as associated converters. This paper presents the obtained optimal sizing curves for the hybrid system (Ppv [kWp], [kg]) by taking into account the predefined constant load (6.5kW) functioning 24/24hours and the system energy balance for a loss-of-load probability LLP=0. These results give the sizes of each subsystem and will make possible to build the best energy flows control mode. [Copyright &y& Elsevier]

Abstract: Hydrogen is considered as the optimal carrier for the surplus energy storage from renewable resources. Although hydrogen and its application in fuel cell is considered as a high-cost energy system, some cost-efficient solutions have been found for their use in stand-alone applications, which usually depend on the variability of renewable sources that have to be oversized in order to reduce their dependence on external energy sources. This paper shows the results from the simulation of several alternatives of introducing hydrogen technologies to increase the independence of a remote-telecom application fed by photovoltaic panels. Hydrogen is obtained by electrolysis and it is used in a fuel cell when the renewable energy source is not enough to maintain the stand-alone application. TRNSYS simulation environment has been used for evaluating the proposed alternatives. The results show that the best configuration option is that considering the use of hydrogen as a way to storage the surplus of radiation and the management system can vary the number of photovoltaic panels assigned to feed the hydrogen generation, the batteries or the telecom application. [Copyright &y& Elsevier]

Abstract: This paper describes the general architecture of a hybrid energy system, whose main components are a proton exchange membrane fuel cell, a battery pack and an ultracapacitor pack as power sources, and metal hydride canisters as energy storage devices, suitable for supplying power to small mobile non-automotive devices in a flexible and variable way. The first experimental results carried out on a system prototype are described, showing that the extra components, required in order to manage the hybrid system, do not remarkably affect the overall system efficiency, which is always higher than 36% in all the test configurations examined. In fact, the system allows the fuel cell to work most often at quasi-optimal conditions, near its maximum efficiency (i.e. at low/medium loads), because high external loads are met by the combined effort of the fuel cell and the ultracapacitors. For the same reason, the metal hydride storage system can be used also under highly dynamic operating conditions, notwithstanding its usually poor kinetic performance. [Copyright &y& Elsevier]

Abstract: Wind generation is substantially increasing its share in the electricity generation portfolio in many countries. In the case of Spain, it can more than double in the next 4 years, reaching a 20GW level. To become competitive in a liberalized market, wind energy reliability requirements should be guaranteed, so storage systems are being considered to avoid the impact of the lack of adequate winds on the electricity generation process. This paper, assuming different scenarios for the electricity markets and the wind farm operation, analyzes the minimum requirements on energy efficiency of a storage system based on the use of hydrogen as energy vector to become economically competitive for each of those scenarios. Simulation of a wind park with such a buffer system for different operation scenarios shows a direct dependence of the economical profit on the energy efficiency of this hydrogen backup system. A direct conclusion of the study is the necessity for an improvement of the currently available values of the efficiency of the subsystems that compose the hydrogen buffer. These improvements seem to be possible in the short term when attending to the current research efforts. [Copyright &y& Elsevier]

Abstract: A stand-alone renewable-energy system employing a hydrogen-based energy store is now being commissioned within the HaRI project at West Beacon Farm, Leicestershire, UK. The interconnection of the various generators, loads and storage system is made through a central DC busbar: an arrangement that is believed to be unique within systems of this type and scale. The rotating generators, such as the wind turbines, are connected through standard industrial drives operating in regenerative mode, while the DC devices—electrolyser, fuel cell and solar photovoltaic array—employ custom DC–DC converters. This paper reviews the design philosophy of the electrical system and the various converters required. Modelling and simulation of the system is discussed along with practical lessons learnt from its implementation and some initial results are presented. [Copyright &y& Elsevier]

An electrolyzer and a fuel cell have been integrated in a small-scale stand-alone renewable energy system to demonstrate that hydrogen can be used for long-term stationary energy storage. The economic and environmental performance of such a system is strongly related to the ability of the electrolyzer to convert electrical energy to hydrogen and the ability of the fuel cell to convert hydrogen back to electrical energy, which together define the round-trip efficiency of the hydrogen storage system. One promising way to improve the efficiency as well as to decrease the capital costs of the fuel cell is to recuperate the oxygen from the electrolyzer and use it as the fuel cell oxidant instead of compressed air. This paper presents the modifications made to the system in order to implement oxygen recuperation. The round-trip system efficiency was found to be 18% with oxygen recuperation and 13.5% without it. [Copyright &y& Elsevier]