Pre-feasibility study of stand-alone hybrid energy systems for applications in Newfoundland

A potential solution for stand-alone power generation is to use a hybrid energy system in parallel with some hydrogen energy storage. In this paper, a pre-feasibility study of using hybrid energy systems with hydrogen as an energy carrier for applications in Newfoundland, Canada is explained. Various renewable and non-renewable energy sources, energy storage methods and their applicability in terms of cost and performance are discussed. HOMER is used as a sizing and optimization tool. Sensitivity analysis with wind speed data, solar radiation level, diesel price and fuel cell cost was done. A remote house having an energy consumption of 25 kW h/d with a 4.73 kW peak power demand was considered as the stand-alone load. It was found that, a wind–diesel–battery hybrid system is the most suitable solution at present. However, with a reduction of fuel cell cost to 15% of its current value, a wind–fuel cell system would become a superior choice. Validity of such projection and economics against conventional power sources were identified. Sizing, performance and various cost indices were also analyzed in this paper.     

Hybrid energy storage systems for stand-alone electric power systems: optimization of system performance and cost through control strategies

The development of remote, renewable-based energy is hindered in part by the lack of affordable energy storage. Requiring power-on-demand from an energy system powered by intermittent or seasonal sources may necessitate one-month’s energy storage—an expensive proposition using conventional storage technologies. If multiple energy storage devices with complementary performance characteristics are used together, the resulting ‘hybrid energy-storage system’ can dramatically reduce the cost of energy storage over single storage systems. The coupling of conventional storage batteries with emerging hydrogen technologies provides one such hybrid system. Hydrogen energy storage in this context includes an electrolyzer, hydrogen storage tank, and a fuel cell. An additional component that must be considered is the control system that determines when the various components are used. Since the control system has an effect on component sizes and thus system and operating costs, the control algorithm must be carefully considered for any system with energy storage. For this study, a time-dependent model of a stand-alone, solar powered, battery-hydrogen hybrid energy storage system was developed to investigate energy storage options for cases where supply and demand of energy are not well matched daily or seasonally. Simulations were performed for residential use with measured solar fluxes and simulated hourly loads for a site at Yuma, Arizona, USA, a desert climate at 32.7 N latitude. Renewable-based power not needed to satisfy the load is stored for later use. Two hybrid energy-storage algorithms were considered. The first is a conventional ‘state-of-charge’ control system that uses the current state of the storage system for control. The second control system presumes knowledge of future demand through a feed-forward, neural net or other ‘intelligent’ control systems. Both algorithms use battery storage to provide much of the daily energy shifting and hydrogen to provide seasonal energy shifting, thus using each storage technology to its best advantage. The cost of storing energy with a hybrid energy-storage scheme was found to be much less expensive than either single storage method, with a hybrid system storage costing 48% of the cost of a hydrogen-only system and only 9% of the cost of a conventional, battery-only system. In addition, the neural-net control system is compared to a standard battery state-of-charge control scheme, and it is shown that neural-net control systems better utilize expensive components and result in less expensive electric power than state-of-charge control systems.     

The potential for integration of hydrogen for complete energy self-sufficiency in residential buildings with photovoltaic and battery storage systems

This paper presents an analysis of energy production in a pilot building located in Slovenia, which is a typical residential house with an installed photovoltaic (PV) system and pilot battery storage system. Energy management system gathers data from smart meters every 15 min. As the pilot building location is in central Europe, complete energy self-sufficiency cannot be provided. The most problematic period of energy production with photovoltaic systems is winter. Solar radiation during the winter is much lower than in the summer and sometimes snow covers photovoltaic panels and disables energy production. Energy production and energy consumption are analyzed for one year. This study shows that complete self-sufficiency can be achieved by supplementing photovoltaic systems with hydrogen fuel cells. The amount of hydrogen, which would suffice for complete self-sufficiency for the whole period, is calculated according to the analyzed data. A synergy between photovoltaic system and hydrogen fuel cells is a step forward to complete self-sufficiency with renewable energy sources. The share of self-sufficiency of a hybrid PV fuel cell system would be 62.13%, meaning that there is no possibility for complete self-sufficiency from the pilot system. The shortage of hydrogen is 144.24 kg for one year and for achieving complete energy self-sufficiency, PV system should be bigger. A hybrid system with photovoltaic system, battery storage system and hydrogen fuel cells can be a solution for complete self-sufficiency. From an economic point of view, such systems are accessible for commercial use. The initial investment is relatively high, because of the high cost of the hydrogen storage tank.     

Optimal energy management system for stand-alone wind turbine/photovoltaic/hydrogen/battery hybrid system with supervisory control based on fuzzy logic

This paper presents a novel hourly energy management system (EMS) for a stand-alone hybrid renewable energy system (HRES). The HRES is composed of a wind turbine (WT) and photovoltaic (PV) solar panels as primary energy sources, and two energy storage systems (ESS), which are a hydrogen subsystem and a battery. The WT and PV panels are made to work at maximum power point, whereas the battery and the hydrogen subsystem, which is composed of fuel cell (FC), electrolyzer and hydrogen storage tank, act as support and storage system. The EMS uses a fuzzy logic control to satisfy the energy demanded by the load and maintain the state-of-charge (SOC) of the battery and the hydrogen tank level between certain target margins, while trying to optimize the utilization cost and lifetime of the ESS. Commercial available components and an expected life of the HRES of 25 years were considered in this study. Simulation results show that the proposed control meets the objectives established for the EMS of the HRES, and achieves a total cost saving of 13% over other simpler EMS based on control states presented in this paper.     

Hybridized off-grid fuel cell/wind/solar PV /battery for energy generation in a small household: A multi-criteria perspective

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.     

Optimisation and techno-economic analysis of autonomous photovoltaic–wind hybrid energy systems in comparison to single photovoltaic and wind systems

A techno-economic analysis for autonomous small scale photovoltaic–wind hybrid energy systems is undertaken for optimisation purposes in the present paper. The answer to the question whether a hybrid photovoltaic–wind or a single photovoltaic or wind system is techno-economically better is also sought. Monthly analysis of 8 year long measured hourly weather data shows that solar and wind resources vary greatly from one month to the next. The monthly combinations of these resources lead to basically three types of months: solar-biased month, wind-biased month and even month. This, in turn, leads to energy systems in which the energy contributions from photovoltaic and wind generators vary greatly. The monthly and yearly system performances simulations for different types of months show that the system performances vary greatly for varying battery storage capacities and different fractions of photovoltaic and wind energy. As well as the system performance, the optimisation process of such hybrid systems should further consist of the system cost. Therefore, the system performance results are combined with system cost data. The total system cost and the unit cost of the produced electricity (for a 20 year system lifetime) are analysed with strict reference to the yearly system performance. It is shown that an optimum combination of the hybrid photovoltaic–wind energy system provides higher system performance than either of the single systems for the same system cost for every battery storage capacity analysed in the present study. It is also shown that the magnitude of the battery storage capacity has important bearings on the system performance of single photovoltaic and wind systems. The single photovoltaic system performs better than a single wind system for 2 day storage capacity, while the single wind system performs better for 1.25 day storage capacity for the same system cost.     

Flexibility improvement evaluation of hydrogen storage based on electricity–hydrogen coupled energy model

To achieve carbon neutrality by 2060, decarbonization in the energy sector is crucial. Hydrogen is expected to be vital for achieving the aim of carbon neutrality for two reasons: use of power-to-hydrogen (P2H) can avoid carbon emissions from hydrogen production, which is traditionally performed using fossil fuels; Hydrogen from P2H can be stored for long durations in large scales and then delivered as industrial raw material or fed back to the power system depending on the demand. In this study, we focus on the analysis and evaluation of hydrogen value in terms of improvement in the flexibility of the energy system, particularly that derived from hydrogen storage. An electricity–hydrogen coupled energy model is proposed to realize the hourly-level operation simulation and capacity planning optimization aiming at the lowest cost of energy. Based on this model and considering Northwest China as the region of study, the potential of improvement in the flexibility of hydrogen storage is determined through optimization calculations in a series of study cases with various hydrogen demand levels. The results of the quantitative calculations prove that effective hydrogen storage can improve the system flexibility by promoting the energy demand balance over a long term, contributing toward reducing the investment cost of both generators and battery storage and thus the total energy cost. This advantage can be further improved when the hydrogen demand rises. However, a cost reduction by 20% is required for hydrogen-related technologies to initiate hydrogen storage as long-term energy storage for power systems. This study provides a suggestion and reference for the advancement and planning of hydrogen storage development in regions with rich sources of renewable energy.     

Optimal energy management strategy of fuel-cell battery hybrid electric mining truck to achieve minimum lifecycle operation costs

Proton exchange membrane fuel cell (PEMFC) electric vehicle is an effective solution for improving fuel efficiency and onboard emissions, taking advantage of the high energy density and short refuelling time. However, the higher cost and short life of the PEMFC system and battery in an electric vehicle prohibit the fuel cell electric vehicle (FCEV) from becoming the mainstream transportation solution. The fuel efficiency-oriented energy management strategy (EMS) cannot guarantee the improvement of total operating costs. This paper proposes an EMS to minimize the overall operation costs of FCEVs, including the cost of hydrogen fuel, as well as the cost associated with the degradations of the PEMFC system and battery energy storage system (ESS). Based on the PEMFC and battery performance degradation models, their remaining useful life (RUL) models are introduced. The control parameters of the EMS are then optimized using a meta-model based global optimization algorithm. This study presents a new optimal control method for a large mining truck operating on a real closed-road operation cycle, using the combined energy efficiency and performance degradation cost measures of the PEMFC system and lithium-ion battery ESS. Simulation results showed that the proposed EMS could improve the total operating costs and the life of the FCEV.     

Dynamic modelling and multi-objective optimization of off-grid hybrid energy systems by using battery or hydrogen storage for different climates

The energy storage problem is an essential issue in renewable energy-based power systems. A comprehensive study is performed to evaluate off-grid hybrid renewable energy systems with a battery bank or a hydrogen system employed as the energy storage option. Dynamic modelling is proposed to see daily and seasonally changes in the system. The economic feasibility of the system and its environmental impacts are investigated in three locations. A multi-objective optimization method based on the Taguchi approach is employed to minimize both levelized cost of energy and the CO₂ emissions. Various weight factors were assigned to understand the response of different optimization targets. The results highlight that the hybridization of energy resources allows the annual emissions to be cut by 68–78% for battery storage, 84–90% for hydrogen storage, compared to a diesel-only system. Despite having higher costs, the systems with hydrogen storage can store energy in the long term; therefore, they have lower CO₂ emissions.     

Hybrid Hydrogen Home Storage for Decentralized Energy Autonomy

As the share of distributed renewable power generation increases, high electricity prices and low feed-in tariff rates encourage the generation of electricity for personal use. In the building sector, this has led to growing interest in energy self-sufficient buildings that feature battery and hydrogen storage capacities. In this study, we compare potential technology pathways for residential energy storage in terms of their economic performance by means of a temporal optimization model of the fully self-sufficient energy system of a single-family building, taking into account its residential occupancy patterns and thermal equipment. We show for the first time how heat integration with reversible solid oxide cells (rSOCs) and liquid organic hydrogen carriers (LOHCs) in high-efficiency, single-family buildings could, by 2030, enable the self-sufficient supply of electricity and heat at a yearly premium of 52% against electricity supplied by the grid. Compared to lithium-ion battery systems, the total annualized cost of a self-sufficient energy supply can be reduced by 80% through the thermal integration of LOHC reactors and rSOC systems.     

Experimental results for hybrid energy storage systems coupled to photovoltaic generation in residential applications

An experimental solar-hydrogen powered residence simulator was built and tested. The system consisted of a solar photovoltaic array connected to an electrolyzer which produced hydrogen as a means of energy storage. The hydrogen was used to produce electricity in a fuel cell that operated in parallel with a battery to meet dynamic power demand similar to that found in residential applications. The study demonstrated the technical feasibility of operating such a system under the simultaneous dynamics of solar input and load. Limitations of current fuel cell and electrolyzer designs, as they pertain to both power delivery and energy storage, were identified. The study also established the need to understand and address dynamic performance in the design and application of solar-hydrogen reversible fuel cell hybrid systems. An economic analysis found that major cost reductions would need to be achieved for such systems to compete with conventional energy storage devices.     

Renewable energy integration through optimal unit commitment and electricity storage in weak power networks

In this work, the impact of intermittent renewable energy sources on total production cost is evaluated, using annual data regarding the isolated power system of the island of Cyprus. Once electrical energy storage (EES) is identified as an approach enhancing flexibility and reliability, the selected EES facilities are modelled and evaluated via a life-cycle cost analysis, based on the most realistic characteristics and cost metrics found in the literature. The results derived from the uncertainty analysis performed, show that vanadium-redox flow battery provides the highest net present value (NPV). However, sodium-sulfur battery system offers the most secure investment in terms of uncertainty range and mean value, followed by lead-acid battery system. Lithium-ion battery system exhibits expensive capital cost which still governs its overall cost performance achieving a negative mean NPV far below zero.     

Extended-power pinch analysis (EPoPA) for integration of renewable energy systems with battery/hydrogen storages

An extended-power pinch analysis (EPoPA) is proposed as a means of extending the power pinch analysis (PoPA) for optimal design of renewable energy systems with battery and hydrogen storage (RES-BH). The EPoPA concept is based on the storage of wasted electricity that cannot be stored by the battery bank designed by PoPA. This energy is stored in the form of hydrogen and is discharged in the form of electricity when the external electricity source is needed. EPoPA graphical and numerical tools are introduced to determine the minimum required external electricity source, wasted electricity sources, and appropriate hydrogen storage system capacity of the RES-BH system during first and normal operation years. Furthermore, the integration of the RES-BH system with a diesel generator as a high reliable system is investigated in view point of economic. The optimal sizes of diesel generator and hydrogen storage system components, such as electrolyzer, fuel cell and hydrogen tank are obtained with the minimization of the total annual cost (TAC) of the system. The implementation results of the EPoPA tools on three possible case studies indicate that EPoPA, unlike other process integration methodologies such as PoPA, is able to optimally design RES-BH systems.     

Performance analysis of various hybrid renewable energy systems using battery,hydrogen, and pumped hydro‐based storage units

The aim of this research is to analyze the techno‐economic performance of hybrid renewable energy system (HRES) using batteries, pumped hydro‐based, and hydrogen‐based storage units at Sharurah, Saudi Arabia. The simulations and optimization process are carried out for nine HRES scenarios to determine the optimum sizes of components for each scenario. The optimal sizing of components for each HRES scenario is determined based on the net present cost (NPC) optimization criterion. All of the nine optimized HRES scenarios are then evaluated based on NPC, levelized cost of energy, payback period, CO₂ emissions, excess electricity, and renewable energy fraction. The simulation results show that the photovoltaic (PV)‐diesel‐battery scenario is economically the most viable system with the NPC of US$2.70 million and levelized cost of energy of US$0.178/kWh. Conversely, PV‐diesel‐fuel cell system is proved to be economically the least feasible system. Moreover, the wind‐diesel‐fuel cell is the most economical scenario in the hydrogen‐based storage category. PV‐wind‐diesel‐pumped hydro scenario has the highest renewable energy fraction of 89.8%. PV‐wind‐diesel‐pumped hydro scenario is the most environment‐friendly system, with an 89% reduction in CO₂ emissions compared with the base‐case diesel only scenario. Overall, the systems with battery and pumped hydro storage options have shown better techno‐economic performance compared with the systems with hydrogen‐based storage.     

Sizing optimization,dynamic modeling and energy management strategies of a stand-alone PV/hydrogen/battery-based hybrid system

This paper presents a sizing method and different control strategies for the suitable energy management of a stand-alone hybrid system based on photovoltaic (PV) solar panels, hydrogen subsystem and battery. The battery and hydrogen subsystem, which is composed of fuel cell (FC), electrolyzer and hydrogen storage tank, act as energy storage and support system. In order to efficiently utilize the energy sources integrated in the hybrid system, an appropriate sizing is necessary. In this paper, a new sizing method based on Simulink Design Optimization (SDO) of MATLAB was used to perform a technical optimization of the hybrid system components. An analysis cost has been also performed, in that the configuration under study has been compared with those integrating only batteries and only hydrogen system. The dynamic model of the designed hybrid system is detailed in this paper. The models, implemented in MATLAB-Simulink environment, have been designed from commercially available components. Three control strategies based on operating modes and combining technical-economic aspects are considered for the energy management of the hybrid system. They have been designed, primarily, to satisfy the load power demand and, secondarily, to maintain a certain level at the hydrogen tank (hydrogen energy reserve), and at the state of charge (SOC) of the battery bank to extend its life, taking into account also technical-economic analysis. Dynamic simulations were performed to evaluate the configuration, sizing and control strategies for the energy management of the hybrid system under study in this work. Simulation results show that the proposed hybrid system with the presented controls is able to provide the energy demanded by the loads, while maintaining a certain energy reserve in the storage sources.     

Information Gap Decision Theory-based day-ahead scheduling of energy communities with collective hydrogen chain

Hydrogen is called to play a vital role in the future decarbonization of the electricity industry. Among its multiple applications, this energy carrier may improve the energy storage, replacing or complementing the traditional battery banks thanks to its higher energy density. However, the low efficiency and cost of associated devices as well as the difficulty in transport make unfeasible the implantation of hydrogen storage systems at the residential level. However, emerging paradigms like energy communities may change this concept making viable the installation of hydrogen chains in the domestic sector. This paper focuses on day-ahead scheduling of energy communities with integrated collective hydrogen storage system. To this end, a three-stage methodology is developed in which the first level is focused on individual home energy management, the second level handles with peer-to-peer energy trading among prosumers and the last level determines the energy exchanging profile with the utility grid accounting with the hydrogen chain. To handle with uncertainties from renewable sources, demand and energy price, the Information Gap Decision Theory (IGDT) is employed, by which an uncertainty-aware scheduling program can be obtained minimizing the negative effects of uncertain parameters. A case study is performed on a six-prosumer energy community with electrolysis, hydrogen vessel and fuel-cell, allowing both purchasing and selling energy with the grid. The results serve to prove the effectiveness of the developed methodology as well as demonstrate the possible impact of unknowns in energy community operation, and how the hydrogen chain can help to improve the economy and self-sufficiency of the system.     

Exploring the feasibility of green hydrogen production using excess energy from a country-scale 100% solar-wind renewable energy system

When planning large-scale 100% renewable energy systems (RES) for the year 2050, the system capacity is usually oversized for better supply-demand matching of electrical energy since solar and wind resources are highly intermittent. This causes excessive excess energy that is typically dissipated, curtailed, or sold directly. The public literature shows a lack of studies on the feasibility of using this excess for country-scale co-generation. This study presents the first investigation of utilizing this excess to generate green hydrogen gas. The concept is demonstrated for Jordan using three solar photovoltaic (PV), wind, and hybrid PV-wind RESs, all equipped with Lithium-Ion battery energy storage systems (ESSs), for hydrogen production using a polymer electrolyte membrane (PEM) system. The results show that the PV-based system has the highest demand-supply fraction (>99%). However, the wind-based system is more favorable economically, with installed RES, ESS, and PEM capacities of only 23.88 GW, 2542 GWh, and 20.66 GW. It also shows the highest hydrogen annual production rate (172.1 × 10³ tons) and the lowest hydrogen cost (1.082 USD/kg). The three systems were a better option than selling excess energy directly, where they ensure annual incomes up to 2.68 billion USD while having payback periods of as low as 1.78 years. Furthermore, the hydrogen cost does not exceed 2.03 USD/kg, which is significantly lower than the expected cost of hydrogen (3 USD/kg) produced using energy from fossil fuel-based systems in 2050.     

Utilization of renewable hybrid energy for refueling station in Al-Kharj,Saudi Arabia

Hydrogen is one of the energy carriers that can be produced using different techniques. Combining multiple energy sources can enhance hydrogen production and meet other electrical demands. The hybrid arrangement allows the produced hydrogen to be stored and used when the electrical energy sources are not adequate. In this study, utilizing the meteorological data was investigated using HOMER (Hybrid Optimization of Multiple Energy Resources) software for the optimal solution. The results demonstrated that the “best-optimized system has 270 kW of photovoltaic (PV), 1 unit of 300 kW of wind turbine (WT), 500 kW of electrolyzer, 100 kg/L of the hydrogen tank, 70 units of 1 kWh lithium-ion battery, and 472 kW of the converter. The selected hybrid energy system has the lowest Levelized cost of energy (LCOE), Levelized cost of hydrogen (LCOH), and net present cost (NPC) of $/kg 0.6208, $/kg 9.34, and $ 484,360.00 respectively which judged the system to be the best choice for the proposed hydrogen project in AI-Kharj. This investigation will help stakeholders and policymakers optimize hybrid energy systems that economically meet the hydrogen production and refueling station demands of the AI-Kharj community.     

Dynamic simulation of hydrogen-based zero energy buildings with hydrogen energy storage for various climate conditions

Solar energy systems are an effective way to meet the needs of zone heating, cooling, electricity, and domestic hot water. However, to reach sustainability, and energy storage unit should be considered for installation. In this study, two combined cooling, heating and power (CCHP) systems are simulated and studied using TRNSYS software; both using natural gas engine generators and photovoltaics as prime movers and a hydrogen fuel cell/electrolyzer storage unit, one with absorption chiller and another with compression chiller cooling. For the study, a residential building is modeled for three major populated climate zones of the United States of America, namely, Hot-humid, mixed-humid and cold using DesignBuilder and EnergyPlus software. The energy demand for its HVAC operation and domestic electricity is obtained and used for system simulation in TRNSYS software. Due to choosing actual equipment for the CCHP arrangement, precise economic and environmental models are designed to further evaluate the possibility of execution of the system. The results show that absorption chiller-equipped CCHP has better performance both environmentally and economically. In addition, the outcome shows that the suggested systems show less favorability to be utilized in hot humid climate zones.     

Hybrid energy management with respect to a hydrogen energy system and demand response

A Hybrid Energy System (HES) is a mechanism that combines multiple sources of energy connected together to achieve synchronised energy output. However, increased energy consumption, operator energy expenses, and the potential environmental impact of increased emissions from the exhaustion of non-renewable energy resources (fossil fuel) pose major challenges to HES. This research is to conduct energy management strategy based on a demand response (DR) program and a hydrogen storage system by designing a Program Logic Controller (PLC) unit. The hybrid system is evaluated by comparing different scenarios such as a hydrogen energy system and demand response. The purpose of this research is to reducing peak demand, minimise the cost of the system and also to extract surplus power generation out of the rate of the battery. This can be achieved by improving the system performances and by eliminating any degradation at the early stages. Organisations or companies must be sure their systems are working properly and that their investments will pay off.