Cost–benefit analysis of remote hybrid wind–diesel power stations: Case study Aegean Sea islands

More than one third of world population has no direct access to interconnected electrical networks. Hence, the electrification solution usually considered is based on expensive, though often unreliable, stand-alone systems, mainly small diesel-electric generators. Hybrid wind–diesel power systems are among the most interesting and environmental friendly technological alternatives for the electrification of remote consumers, presenting also increased reliability. More precisely, a hybrid wind–diesel installation, based on an appropriate combination of a small diesel-electric generator and a micro-wind converter, offsets the significant capital cost of the wind turbine and the high operational cost of the diesel-electric generator. In this context, the present study concentrates on a detailed energy production cost analysis in order to estimate the optimum configuration of a wind–diesel-battery stand-alone system used to guarantee the energy autonomy of a typical remote consumer. Accordingly, the influence of the governing parameters—such as wind potential, capital cost, oil price, battery price and first installation cost—on the corresponding electricity production cost is investigated using the developed model. Taking into account the results obtained, hybrid wind–diesel systems may be the most cost-effective electrification solution for numerous isolated consumers located in suitable (average wind speed higher than 6.0 m/s) wind potential regions.     

Power quality improvement of a stand-alone power system subjected to various disturbances

In wind-diesel stand-alone power systems, the disturbances like random nature of wind power, turbulent wind, sudden changes in load demand and the wind park disconnection effect continuously the system voltage and frequency. The satisfactory operation of such a system is not an easy task and the control design has to take in to account all these subtleties. For maintaining the power quality, generally, a short-term energy storage device is used. In this paper, the performance of a wind-diesel system associated with a superconducting magnetic energy storage (SMES) system is studied. The effect of installing SMES at wind park bus/load bus, on the system performance is investigated. To control the exchange of real and reactive powers between the SMES unit and the wind-diesel system, a control strategy based on fuzzy logic is proposed. The dynamic models of the hybrid power system for most common scenarios are developed and the results presented.     

Wind-diesel hybrid power system integration in the south Algeria

In most isolated sites situated in south Algeria, the diesel generators are the major source of electrical energy. Indeed, the power supply of these remote regions still poses order problems (technical, economical and ecological). The electricity produced with the help of diesel generators is very expensive and responsible for CO₂ emission. These isolated sites have significant wind energy potential. Hence, the use of twinning wind-diesel is widely recommended, especially to reduce operating deficits. The objective of this paper is to study the global modeling of a hybrid system which compounds wind turbine generator, diesel generator and storage system. This model is based on the control strategy to optimize the functioning of the hybrid system and to consolidate the gains to provide proper management of energy sources (wind, diesel, battery) depending on the load curve of the proposed site. The management is controlled by a controller which ensures the opening/closing of different power switches according to meteorological conditions (wind speed, air mass, temperature, etc).     

Comparing wind and photovoltaic stand-alone power systems used for the electrification of remote consumers

Wind power and photovoltaic driven stand-alone systems have turned into one of the most promising ways to handle the electrification requirements of numerous isolated consumers worldwide. In this context, the primary target of the present work is to estimate the appropriate dimensions of either a wind power or a photovoltaic stand-alone system that guarantees the energy autonomy of several typical remote consumers located in representative Greek territories. For all regions examined, long-term wind speed and solar radiation measurements as well as formal meteorological data are utilized. Accordingly, special emphasis is put on the detailed energy balance analysis of the proposed systems on an hourly basis, including also the battery bank depth of discharge time evolution. Finally, comparison is made between the wind and the solar based systems investigated, proving that in most Greek regions either a wind or photovoltaic driven stand-alone system is able to cover the electrification needs of remote consumers, at a moderate first installation cost, without any additional energy input.     

Technical and economic assessment of hybrid photovoltaic/wind system with battery storage in Corsica island

The sizing and techno-economical optimization of a stand-alone hybrid photovoltaic/wind system (HPWS) with battery storage is presented in this paper. The main objective of the present study is to find the optimum size of system, able to fulfill the energy requirements of a given load distribution, for three sites located at Corsica island and to analyze the impact of different parameters on the system size. The methodology used provides a useful and simple approach for sizing and analyzing an HPWS. In the proposed stand-alone system, a new concept such as the supply of wind power via a uninterruptible power supply (UPS) is introduced and therefore the energy produced by the wind generator can be sent directly to the load.     

Assessment of economic viability for PV/wind/diesel hybrid energy system in southern Peninsular Malaysia

This paper analyzed the potential implementation of hybrid photovoltaic (PV)/wind turbine/diesel system in southern city of Malaysia, Johor Bahru. HOMER (hybrid optimization model for electric renewable) simulation software was used to determine the technical feasibility of the system and to perform the economical analysis of the system. There were seven different system configurations, namely stand-alone diesel system, hybrid PV–diesel system with and without battery storage element, hybrid wind–diesel system with and without battery storageelement, PV–wind–diesel system with and without storage element, will be studied and analyzed. The simulations will be focused on the net present costs, cost of energy, excess electricity produced and the reduction of CO₂ emission for the given hybrid configurations. At the end of this paper, PV–diesel system with battery storage element, PV–wind–diesel system with battery storage element and the stand-alone diesel system were analyzed based on high price of diesel.     

Potential and economic viability of standalone hybrid systems for a rural community of Sokoto,North-west Nigeria

An assessment of the potential and economic viability of standalone hybrid systems for an off-grid rural community of Sokoto, North-west Nigeria was conducted. A specific electric load profile was developed to suite the community consisting 200 homes, a school and a community health center. The data obtained from the Nigeria Meteorological Department, Oshodi, Lagos (daily mean wind speeds, and daily global solar radiation for 24 years from 1987 to 2010) were used. An assessment of the design that will optimally meet the daily load demand with a loss of load probability (LOLP) of 0.01 was performed, considering 3 stand-alone applications of photovoltaic (PV), wind and diesel, and 3 hybrid designs of wind-PV, wind-diesel, and solar-diesel. The diesel standalone system (DSS) was taken as the basis of comparison as the experimental location has no connection to a distribution network. The HOMER® software optimizing tool was engaged following the feasibility analysis with the RETScreen software. The wind standalone system (WSS) was found to be the optimal means of producing renewable electricity in terms of life cycle cost as well as levelised cost of producing energy at $0.15/(kW$h). This is competitive with grid electricity, which is presently at a cost of approximately $0.09/(kW$h) and 410% better than the conventional DSS at a levelized cost of energy (LCOE) of $0.62/kWh. The WSS is proposed for communities around the study site.     

Techno-economic study of off-grid hybrid photovoltaic/battery and photovoltaic/battery/fuel cell power systems in Kunming,China

The objective of this study is to evaluate the technical and economic feasibility of stand-alone hybrid photovoltaic (PV)/battery and PV/battery/fuel cell (FC) power systems for a community center comprising 100 households in Kunming by using the Hybrid Optimization Model for Electric Renewable (HOMER) software. HOMER is used to define the optimum sizing and techno-economic feasibility of the system equipment based on the geographical and meteorological data of the study region. In this study, different hybrid power systems are analyzed to select the optimum energy system while considering total net present cost (NPC) and levelized cost of energy (COE). The results showed that the optimal hybrid PV/battery system comprised 500 kW PV modules, 1200 7.6-kWh battery units, and 500 kW power converters. The proposed system has an initial cost of $6,670,000, an annual operating cost of $82,763/yr, a total NPC of $7,727,992, and a levelized COE of $1.536/kWh. While the PV/battery/FC power system is possible, the cost increases were due to the investment cost of the FC system. The optimal PV/battery/FC system has an initial cost of $6,763,000, an annual operating cost of $82,312/yr, a total NPC of $7,815,223, and a levelized COE of $1.553/kWh.     

Optimal sizing method for stand-alone hybrid solar–wind system with LPSP technology by using genetic algorithm

System power reliability under varying weather conditions and the corresponding system cost are the two main concerns for designing hybrid solar–wind power generation systems. This paper recommends an optimal sizing method to optimize the configurations of a hybrid solar–wind system employing battery banks. Based on a genetic algorithm (GA), which has the ability to attain the global optimum with relative computational simplicity, one optimal sizing method was developed to calculate the optimum system configuration that can achieve the customers required loss of power supply probability (LPSP) with a minimum annualized cost of system (ACS). The decision variables included in the optimization process are the PV module number, wind turbine number, battery number, PV module slope angle and wind turbine installation height. The proposed method has been applied to the analysis of a hybrid system which supplies power for a telecommunication relay station, and good optimization performance has been found. Furthermore, the relationships between system power reliability and system configurations were also given.     

Minimization of the energy storage requirements of a stand‐alone wind power installation by means of photovoltaic panels

Autonomous wind power systems are among the most interesting and environmentally friendly technological solutions for the electrification of remote consumers. In many cases, however, the battery contribution to the initial or the total operational cost is found to be dominant, discouraging further penetration of the available wind resource. This is basically the case for areas possessing a medium–low wind potential. On the other hand, several isolated consumers are located in regions having the regular benefit of an abundant and reliable solar energy supply. In this context the present study investigates the possibility of reducing the battery size of a stand‐alone wind power installation by incorporating a small photovoltaic generator. For this purpose an integrated energy production installation based exclusively on renewable energy resources is hereby proposed. Subsequently a new numerical algorithm is developed that is able to estimate the appropriate dimensions of a similar system. According to the results obtained by long‐term experimental measurements, the introduction of the photovoltaic panels considerably improves the operational and financial behaviour of the complete installation owing to the imposed significant battery capacity diminution. Copyright © 2006 John Wiley & Sons, Ltd.     

An integrated model for performance simulation of hybrid wind–diesel systems

Stand-alone hybrid systems have turned into one of the most promising ways to handle the electrification requirements of numerous isolated consumers worldwide. The proposed wind–diesel–battery hybrid system consists of a micro-wind converter, a small diesel-electric generator—basically operating as a back up energy production system—and a lead-acid battery bank that stores the wind energy surplus during high wind speed periods. In this context the present work is focused on presenting a detailed mathematical model describing the operational behavior of the basic hybrid system components, along with the representative calculation results based on the developed mathematical model. Accordingly, an integrated numerical algorithm is built to estimate the energy autonomy configuration of the hybrid system under investigation. Using the proposed numerical algorithm, the optimum configuration selection procedure is verified by carrying out an appropriate sensitivity analysis. The proposed methodology may equally well be applied to any other remote consumer and wind potential type, in order to estimate the optimum wind–diesel hybrid system configuration that guarantees long-term energy autonomy.     

储能电池在风光互补发电系统中的容量配置分析

储能电池是分布式发电系统的关键组件。增加储能电池的容量可以提高发电系统的可靠性,但会增加系统的投资和运行费用。基于上海地区全年8 760 h的气象数据,计算了风光互补发电系统在不同储能容量下的负荷缺电率和能量溢出率的变化。对于独立的风光互补发电系统,在满足能量溢出率小于0.3的情况下,如果系统缺电率维持在1%左右时,需要配置3天的储能容量;如果系统缺电率为0,则需要配置5天的储能容量。     

Optimal sizing study of hybrid wind/PV/diesel power generation unit

In this paper, a methodology of sizing optimization of a stand-alone hybrid wind/PV/diesel energy system is presented. This approach makes use of a deterministic algorithm to suggest, among a list of commercially available system devices, the optimal number and type of units ensuring that the total cost of the system is minimized while guaranteeing the availability of the energy. The collection of 6 months of data of wind speed, solar radiation and ambient temperature recorded for every hour of the day were used. The mathematical modeling of the main elements of the hybrid wind/PV/diesel system is exposed showing the more relevant sizing variables. A deterministic algorithm is used to minimize the total cost of the system while guaranteeing the satisfaction of the load demand. A comparison between the total cost of the hybrid wind/PV/diesel energy system with batteries and the hybrid wind/PV/diesel energy system without batteries is presented.The reached results demonstrate the practical utility of the used sizing methodology and show the influence of the battery storage on the total cost of the hybrid system.     

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.     

Optimal sizing of stand-alone hybrid systems based on PV/WT/FC by using several methodologies

This paper presents a comparative study of four sizing methods for a stand-alone hybrid generation system integrating renewable energies (photovoltaic panels and wind turbine) and backup and storage system based on battery and hydrogen (fuel cell, electrolyzer and hydrogen storage tank). Two of them perform a technical sizing. In one case, the sizing is based on basic equations, and in the other case, an optimal technical sizing is achieved by using Simulink Design Optimization. The other two methods perform an optimal techno-economical sizing by using the hybrid system optimization software HOMER and HOGA, respectively. These methods have been applied to design a stand-alone hybrid system which supplies the load energy demand during a year. A MATLAB-Simulink model of the hybrid system has been used to simulate the performance of hybrid system designed by each method for the stand-alone application under study in this work. The results are reported and discussed in the paper.     

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.     

Optimal design and techno-economic analysis of a hybrid solar–wind power generation system

Solar energy and wind energy are the two most viable renewable energy resources in the world. Good compensation characters are usually found between solar energy and wind energy. This paper recommend an optimal design model for designing hybrid solar–wind systems employing battery banks for calculating the system optimum configurations and ensuring that the annualized cost of the systems is minimized while satisfying the custom required loss of power supply probability (LPSP). The five decision variables included in the optimization process are the PV module number, PV module slope angle, wind turbine number, wind turbine installation height and battery capacity. The proposed method has been applied to design a hybrid system to supply power for a telecommunication relay station along south-east coast of China. The research and project monitoring results of the hybrid project were reported, good complementary characteristics between the solar and wind energy were found, and the hybrid system turned out to be able to perform very well as expected throughout the year with the battery over-discharge situations seldom occurred.     

Techno‐economic optimization of hybrid power system using genetic algorithm

This paper presents an optimum sizing methodology to optimize the hybrid energy system (HES) configuration based on genetic algorithm. The proposed optimization model has been applied to evaluate the techno‐economic prospective of the HES to meet the load demand of a remote village in the northern part of Saudi Arabia. The optimum configuration is not achieved only by selecting the combination with the lowest cost but also by finding a suitable renewable energy fraction that satisfies load demand requirements with zero rejected loads. Moreover, the economic, technical and environmental characteristics of nine different HES configurations were investigated and weighed against their performance. The simulation results indicated that the optimum wind turbine (WT) selection is not affected only by the WT speed parameters or by the WT rated power but also by the desired renewable energy fraction. It was found that the rated speed of the WT has a significant effect on optimum WT selection, whereas the WT rated power has no consistent effect on optimal WT selection. Moreover, the results clearly indicated that the HES consisting of photovoltaics (PV), WT, battery bank (Batt) and diesel generator (DG) has superiority over all the nine systems studied here in terms of economical and environmental performance. The PV/Batt/DG hybrid system is only feasible when wind resource is very limited and solar energy density is high. On the other hand, the WT/Batt/DG hybrid system is only feasible at high wind speed and low solar energy density. It was also found that the inclusion of batteries reduced the required DG and hence reduced fuel consumption and operating and maintenance cost. Copyright © 2014 John Wiley & Sons, Ltd.     

Design and techno-economical optimization for hybrid PV/wind system under various meteorological conditions

The optimal design of the renewable energy system can significantly improve the economical and technical performance of power supply. In this paper, the technical-economic optimization study of a stand-alone hybrid PV/wind system (HPWS) in Corsica Island is presented.

Therefore, the primary objective of this study is to estimate the appropriate dimensions of a stand-alone HPWS that guarantee the energy autonomy of a typical remote consumer with the lowest levelised cost of energy (LCE). A secondary aim is to compare the performance and the optimal sizing of two system configurations. Finally, to study the impact of the renewable energy potential quality on the system size, the optimum dimensions of system are defined for five sites in Corsica Island. In this context, a complete sizing model is developed, able to predict the optimum system configuration on the basis of LCE. Accordingly, an integrated energy balance analysis is carried out for the whole time period investigated.

The simulation results indicate that the hybrid system is the best option for all the sites considered in this study, yielding lower LCE. Thus, it provides higher system performance than PV or wind systems alone. The choice of the system configuration type affects the state of charge variation profile, especially at low wind potential sites, while the system size and the LCE are significantly influenced. It is shown that the LCE depends largely on the renewable energy potential quality. At high wind potential site, more than 40% of the total production energy is provided by the wind generator, while at low wind potential sites, less than 20% of total production energy is generated by the wind generator.     

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.