Techno-economic analysis of RES & hydrogen technologies integration in remote island power system

The main objective of the present study is the integration of hydrogen technologies as an energy storage medium in a hybrid power system. The existing power system of the island of Milos, which is based on fossil fuel generators and a small wind park, is assessed in the context of this paper. System level simulation results, from both technical and economic point of view, are presented for the currently existing and the proposed island's hybrid power system. The latter integrates a higher number of wind turbines and hydrogen technologies as energy storage medium, and the two system architectures are being compared taking into account not only technical and economic parameters but also Green House – Gas (GHG) emissions, fossil fuels consumption and Renewable Energy Sources (RES) penetration increase. Moreover, a sensitivity analysis has been performed in order to determine the contribution of hydrogen technologies equipment costs; with the cost of energy produced (COE) being the critical parameter. Results show that COE for the proposed power system is higher than the existing one, but on the other hand GHG emissions and fossil fuel consumption are significantly reduced. In addition, RES penetration increases dramatically and the sensitivity analysis indicates that a further reduction in hydrogen technologies equipment and subsidy on wind turbine costs would make RES & Hydrogen-based systems economically competitive to the existing power system of the island.     

A review on wind energy and wind–hydrogen production in Turkey: A case study of hydrogen production via electrolysis system supplied by wind energy conversion system in Central Anatolian Turkey

Studies about investigation of hydrogen production from wind energy and hydrogen production costs for a specific region were reviewed in this study and it was shown that these studies were rare in the world, especially in Turkey. Therefore, the costs of hydrogen, hydrogen production quantities using a wind energy conversion system were considered as a case study for 5 different locations of Nigde, Kirsehir, Develi, Sinop and Pinarbasi located in the Central Anatolia in Turkey. Annual wind energy productions and costs for different wind energy conversion systems were calculated for 50 m, 80 m and 100 m hub heights. According to wind energy costs calculations, the amounts and costs of hydrogen production were computed. Furthermore, three different scenarios were taken into account to produce much hydrogen. The results showed that the hydrogen production using a wind energy conversion system with 1300 kW rated power had a range from 1665.24 kgH₂/year in Nigde at 50 m hub height to 6288.59 kgH₂/year in Pinarbasi at 100 m hub height. Consequently, Pinarbasi and Sinop have remarkable wind potential and potential of hydrogen production using a wind–electrolyzer energy system.     

Design of hybrid power-to-power systems for continuous clean PV-based energy supply

The increasing penetration of intermittent renewable sources, fostering power sector decarbonization, calls for the adoption of energy storage systems as an essential mean to improve local electricity exploitation, reducing the impact of distributed power generation on the electric grid. This work compares the use of hydrogen-based Power-to-Power systems, battery systems and hybrid hydrogen-battery systems to supply a constant 1 MW_el load with electricity locally generated by a photovoltaic plant. A techno-economic optimization model is set up that optimizes the size and annual operation of the system components (photovoltaic field, electrolyzer, hydrogen storage tanks, fuel cell and batteries) with the objective of minimizing the annual average cost of electricity, while guaranteeing an imposed share of local renewable self-generation. Results show that, with the present values of investment costs and grid electricity prices, the installation of an energy storage system is not economically attractive by itself, whereas the installation of PV panels is beneficial in terms of costs, so that the baseline optimal solution consists of a 4.2 MW_p solar field capable to self-generate 33% of the load annually. For imposed shares of self-generation above 40%, decoupling generation and consumption becomes necessary. The use of batteries is slightly less expensive than the use of hydrogen storage systems up to a 92% self-generation rate. Above this threshold, seasonal storage becomes predominant and hybrid storage becomes cheaper than batteries. The sale of excess electricity is always important to support the plant economics, and a sale price reduction sensibly impacts the results. Hydrogen storage becomes more competitive when the need for medium and long terms energy shift increases, e.g. in case of having a cap on the available PV capacity.     

Development of a viability assessment model for hydrogen production from dedicated offshore wind farms

Dedicated offshore wind farms for hydrogen production are a promising option to unlock the full potential of offshore wind energy, attain decarbonisation and energy security targets in electricity and other sectors, and cope with grid expansion constraints. Current knowledge on these systems is limited, particularly the economic aspects. Therefore, a new, integrated and analytical model for viability assessment of hydrogen production from dedicated offshore wind farms is developed in this paper. This includes the formulae for calculating wind power output, electrolysis plant size, and hydrogen production from time-varying wind speed. All the costs are projected to a specified time using both Discounted Payback (DPB) and Net Present Value (NPV) to consider the value of capital over time. A case study considers a hypothetical wind farm of 101.3 MW situated in a potential offshore wind development pipeline off the East Coast of Ireland. All the costs of the wind farm and the electrolysis plant are for 2030, based on reference costs in the literature. Proton exchange membrane electrolysers and underground storage of hydrogen are used. The analysis shows that the DPB and NPV flows for several scenarios of storage are in good agreement and that the viability model performs well. The offshore wind farm – hydrogen production system is found to be profitable in 2030 at a hydrogen price of €5/kg and underground storage capacities ranging from 2 days to 45 days of hydrogen production. The model is helpful for rapid assessment or optimisation of both economics and feasibility of dedicated offshore wind farm – hydrogen production systems.     

Operation planning of hydrogen storage connected to wind power operating in a power market

In this paper, a methodology for the operation of a hybrid plant with wind power and hydrogen storage is presented. Hydrogen produced from electrolysis is used for power generation in a stationary fuel cell and as fuel for vehicles. Forecasts of wind power are used for maximizing the expected profit from power exchange in a day-ahead market, also taking into account a penalty cost for unprovided hydrogen demand. During online operation, a receding horizon strategy is applied to determine the setpoints for the electrolyzer power and the fuel cell power. Results from three case studies of a combined wind-hydrogen plant are presented. In the first two cases, the plant is assumed to be operating in a power market dominated by thermal and hydropower, respectively. The third case demonstrates that the operating principles are also useful for isolated wind-hydrogen systems with backup generation.     

Rapid sizing of a hydrogen-battery storage for an offshore wind farm using convex programming

This paper carries out a comprehensive analysis on an offshore wind farm equipped with a hybrid storage comprised of hydrogen and battery, from the perspective of economic effectiveness. To rapidly evaluate the system economy, a computationally efficient convex program that takes the nonlinear storage efficiencies into account is provided, which can simultaneously and synergistically optimize the storage sizing and energy management over a long offshore wind cycle. In the analysis, a case study on the optimal configuration and operation of the hybrid storage is thoroughly investigated, answering what the scalings are and how the storage functions in the offshore wind farm. Comparisons to other offshore wind farms with none or only one storage type further demonstrate the advantage of combining hydrogen plant and battery. Influences of the offshore wind electricity price of grid parity and hydrogen price on the system economies, in the terms of total annual cost, net annual profit and hydrogen production cost, are also discussed, revealing sensitivity and dependency of the scalings. Finally, this paper presents the future potential of applying hydrogen plant in the offshore wind farm, from the angles of hydrogen production cost and energy saving.     

Study on optimal configuration of the grid-connected wind–solar–battery hybrid power system

The capacity allocation of each energy unit in the grid-connected wind–solar–battery hybrid power system is a significant segment in system design. In this paper, taking power grid dispatching into account, the research priorities are as follows: (1) We establish the mathematic models of each energy unit in the hybrid power system. (2) Based on dispatching of the power grid, energy surplus rate, system energy volatility and total cost, we establish the evaluation system for the wind–solar–battery power system and use a number of different devices as the constraint condition. (3) Based on an improved Genetic algorithm, we put forward a multi-objective optimisation algorithm to solve the optimal configuration problem in the hybrid power system, so we can achieve the high efficiency and economy of the grid-connected hybrid power system. The simulation result shows that the grid-connected wind–solar–battery hybrid power system has a higher comprehensive performance; the method of optimal configuration in this paper is useful and reasonable.     

考虑制氢效率特性的风氢系统容量优化

针对利用风电制氢导致电解槽间歇式运行的问题,提出了考虑制氢效率特性的风氢系统容量配置优化方法。首先研究了电解槽的制氢效率特性,评估电解槽的最优工作区间;在此基础上,采取电网辅助购电策略,维持电解槽的最优运行;考虑售电收益、售氢收益、投资运维成本和弃风成本,以风氢系统联合收益最大化为目标,计及风氢系统稳定运行约束和风电出力爬坡约束,合理地分配风电上网功率和制氢功率。文章联合风电外送输电工程进行了风氢系统容量配置优化,为风氢系统的容量优化提供新思路。     

Integration of large-scale hydrogen storages in a low-carbon electricity generation system

This study investigates the overall feasibility of large energy storages with hydrogen as energy carrier onsite with a pre-combustion carbon capture and storage coal gasification plant and assesses the general impacts of such a backup installation on an electricity generation system with high wind power portion. The developed system plant configuration consists of four main units namely the gasification unit, main power unit, backup power unit including hydrogen storage and ancillary power unit. Findings show that integrating a backup storage in solid or gaseous hydrogen storage configuration allows to store excessive energy under high renewable power output or low demand and to make use of the stored energy to compensate low renewable output or high power demand. The study concludes that the developed system configuration reaches much higher load factors and efficiency levels than a plant configuration without backup storage, which simply increases its power unit capacity to meet the electricity demand. Also from an economical point of view, the suggested system configurations are capable to achieve lower electricity generation costs.     

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.     

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.     

Charging dynamics of metal hydride hydrogen storage bed for small wind hybrid systems

Small hybrid wind systems are capable of storing and supplying power for residential applications. In this paper, the excess wind energy is converted into hydrogen by electrolysis and is stored in a metal hydride. Metal hydride beds are known for their high volumetric capacity compared to the compressed hydrogen storage, and offers hydrogen storage at a reasonable operating temperature and pressure. A system simulation model is developed in Matlab/Simulink platform for the dynamics of the metal hydride hydrogen storage system, which is charged by the wind energy. The thermal loads of the metal hydride storage system is met by passing water at ambient temperature for cooling the bed while hydrogen is being absorbed. The effect of the transient turbulent wind velocity profile on the storage system is analyzed. The thermal management of the storage system plays an important role in the overall design, and hence it is discussed in detail.     

A comprehensive method for optimal power management and design of hybrid RES-based autonomous energy systems

The power management strategy (PMS) plays an important role in the optimum design and efficient utilization of hybrid energy systems. The power available from hybrid systems and the overall lifetime of system components are highly affected by PMS. This paper presents a novel method for the determination of the optimum PMS of hybrid energy systems including various generators and storage units. The PMS optimization is integrated with the sizing procedure of the hybrid system. The method is tested on a system with several widely used generators in off-grid systems, including wind turbines, PV panels, fuel cells, electrolyzers, hydrogen tanks, batteries, and diesel generators. The aim of the optimization problem is to simultaneously minimize the overall cost of the system, unmet load, and fuel emission considering the uncertainties associated with renewable energy sources (RES). These uncertainties are modeled by using various possible scenarios for wind speed and solar irradiation based on Weibull and Beta probability distribution functions (PDF), respectively. The differential evolution algorithm (DEA) accompanied with fuzzy technique is used to handle the mixed-integer nonlinear multi-objective optimization problem. The optimum solution, including design parameters of system components and the monthly PMS parameters adapting climatic changes during a year, are obtained. Considering operating limitations of system devices, the parameters characterize the priority and share of each storage component for serving the deficit energy or storing surplus energy both resulted from the mismatch of power between load and generation. In order to have efficient power exploitation from RES, the optimum monthly tilt angles of PV panels and the optimum tower height for wind turbines are calculated. Numerical results are compared with the results of optimal sizing assuming pre-defined PMS without using the proposed power management optimization method. The comparative results present the efficacy and capability of the proposed method for hybrid energy systems.     

Dynamic performance of wind-diesel power system with capacitive energy storage

This paper presents an analysis of the dynamic performance of a wind-Diesel power system which operates in isolation from the grid. The simulation studies of the dynamic response are conducted in two different configurations of the power system, firstly, without storage and, secondly, with capacitive energy storage. The frequency and power deviations resulting from a step load disturbance of 1% are presented. It is shown that improvement in the transient responses of the stand alone wind and the hybrid wind-Diesel power system is achieved when capacitive energy storage is included in the systems.     

Role of hydrogen storage in renewable energy management for Ontario

Effective energy storage and management is needed to manage intermittent renewable energy systems. Several jurisdictions around the world are planning to reduce or close their coal power plants to allow for renewable energy expansion, such as Ontario, Canada. Hydrogen storage, which is a promising energy storage option, is capable of meeting energy requirements that will arise from the shutdown of coal plants. In this paper, both economic and environmental feasibility of a hydrogen system linked with wind and hydroelectric plants in Ontario will be investigated. The Princefarm wind power plant and Beck1 hydro plant with production capacities of 189 MW and 490 MW, respectively, are analyzed in a case study for comparison purposes. The environmental analysis demonstrates the advantageous role of hydrogen storage and energy conversion. The overall system life-cycle yields 31.02 g CO₂ eq per 1 kW h power output of the system when hydrogen energy storage is adopted. The payback periods of the systems linked with the Princefarm and Beck1 are also analyzed and found to be about 17 years.     

Integrating power systems for remote island energy supply: Lessons from Mykines,Faroe Islands

This study investigates the challenges and opportunities facing the installation of a hybrid hydrogen-renewable energy system in a remote island area disconnected from any main power grid. Islands with strong wind energy potential have the potential to become self-sufficient energy generating hubs that may even export electricity or hydrogen. This study has tested whether the combination of wind and hydrogen can replace a diesel generator on one of the Faroe Islands, Mykines. The comparison is based on an evaluation of each power system's costs, efficiency, environmental impact and suitability for the Mykines. The findings from this research can help inform those seeking to design 100% renewable energy systems for remote areas, and in particular islands. Furthermore, our comparison has value for those seeking to optimize the integration of wind turbines with hydrogen energy systems.     

Cost analysis of wind-electrolyzer-fuel cell system for energy demand in Pınarbaşı-Kayseri

In this study, the hydrogen production potential and costs by using wind/electrolysis system in P?narba??-Kayseri were considered. In order to evaluate costs and quantities of produced hydrogen, for three different hub heights (50 m, 80 m and 100 m) and two different electrolyzer cases, such as one electrolyzer with rated power of 120 kW (Case-I) and three electrolyzers with rated power of 40 kW (Case-II) were investigated. Levelised cost of electricity method was used in order to determine the cost analysis of wind energy and hydrogen production. The results of calculations brought out that the electricity costs of the wind turbines and hydrogen production costs of the electrolyzers are decreased with the increase of turbine hub height. The maximum hydrogen production quantity was obtained 14192 kgH₂/year and minimum hydrogen cost was obtained 8.5 $/kgH₂ at 100 m hub height in the Case-II.     

The economics of large-scale wind power in the UK A model of an optimally mixed CEGB electricity grid

Previous calculations of the economics of large-scale wind power have been generally limited to the evaluation of the marginal cost of energy, assuming that the addition of a wind farm to an electricity grid does not change the mix of base, intermediate and peak load plant in that grid. Here a simple but powerful numerical generation planning model has been constructed for grids containing wind farms and three classes of thermal power station, but no storage. Electricity demand and available power are specified by empirically based probability distribution functions and the plant mix which minimizes the total annualized costs of the generating system is determined. Capacity credit of wind power is automatically taken into account in the optimization. Using the model, the breakeven costs of wind energy in a model British CEGB grid, containing coal, nuclear, oil and wind driven power plant, are evaluated under various conditions. For a wide range of parameter values, large-scale wind power is likely to be economically competitive in this grid.     

Analysis of the current methods used to size a wind/hydrogen/fuel cell‐integrated system: A new perspective

As an alternative to the production and storage of intermittent renewable energy sources, it has been suggested that one can combine several renewable energy technologies in one system, known as integrated or hybrid system, that integrate wind technology with hydrogen production unit and fuel cells. This work assesses the various methods used in sizing such systems. Most of the published papers relate the use of simulation tools such as HOMER, HYBRID2 and TRNSYS, to simulate the operation of different configurations for a given application in order to select the best economic option. But, with these methods one may not accurately determine certain characteristics of the energy resources available on a particular site, the profiles of estimated consumption and the demand for hydrogen, among other factors, which will be the optimal parameters of each subsystem. For example, velocity design, power required for the wind turbine, power required for the fuel cell and electrolyzer and the storage capacity needed for the system. Moreover, usually one makes excessive use of bi‐parametric Weibull distribution function to approximate the histogram of the observed wind to the theoretical, which is not appropriate when there are bimodal frequency distributions of wind, as is the case in several places in the world. A new perspective is addressed in this paper, based on general system theory, modeling and simulation with a systematic approach and the use of exergoeconomic analysis. There are some general ideas on the advantages offered in this method, which is meant for the implementation of wind/hydrogen/fuel cell‐integrated systems and in‐situ clean hydrogen production. Copyright © 2009 John Wiley & Sons, Ltd.