Off-grid Hybrid Energy System Research Articles

Optimization and assessment of floating and floating-tracking PV systems integrated in on- and off-grid hybrid energy systems

Considering the targets of Thailand in terms of renewable energy exploitation and decarbonization of the shrimp farming sector, this work evaluates several scenarios for optimal integration of hybrid renewable energy systems into a representative shrimp farm. In particular, floating and floating-tracking PV systems are considered as alternatives for the exploitation of solar energy to meet the shrimp farm electricity demand.By developing a dynamic techno-economic simulation and optimization model, the following renewable energy systems have been evaluated: PV and wind based hybrid energy systems, off-grid and on-grid PV based hybrid energy systems, ground mounted and floating PV based hybrid energy systems, and floating and floating-tracking PV based hybrid energy systems.From a water-energy nexus viewpoint, floating PV systems have shown significant impacts on the reduction of evaporation losses, even if the energy savings for water pumping are moderate due to the low hydraulic head. Nevertheless, the study on the synergies between water for food and power production has highlighted that the integration of floating PV represents a key solution for reducing the environmental impacts of shrimp farming. For the selected location, the results have shown that PV systems represent the best renewable solution to be integrated into a hybrid energy system due to the abundance of solar energy resources as compared to the moderate wind resources. The integration of PV systems in off-grid configurations allows to reach high renewable reliabilities up to 40% by reducing the levelized cost of electricity. Higher renewable reliabilities can only be achieved by integrating energy storage solutions but leading to higher levelized cost of electricity. Although the floating-tracking PV systems show higher investment costs as compared to the reference floating PV systems, both solutions show similar competiveness for reliabilities up to 45% due to the higher electricity production of the floating-tracking PV systems. The higher electricity production from the floating-tracking PV systems leads to a better competitiveness for reliabilities higher than 90% due to lower capacity requirements for the storage systems.

Design of an Optimal off-grid Hybrid Energy System for a Rural Community

This paper presents an optimized off-grid PV-diesel generator-battery hybrid energy system for application in an un-electrified rural community and further outlines a procedure for designing such an economical and technically feasible hybrid system. The hybrid optimization model for multiple energy resources (HOMER) software was utilized for simulation and analysis. The criteria of minimum net present cost of system, low CO 2 emissions and zero electric load rejection was applied while considering technical issues of PV array, inverter coordination and PV capacity penetration level. For the case study system used, the obtained optimized hybrid energy system configuration is as follows: 68kW PV plant; 40kW Diesel plant; 45.4kW Inverter; and 80kWh battery unit. The proposed hybrid energy system is capable of producing 157685kWh of electricity annually at a levelized cost of energy of 0.55 $/kWh while emitting 51,000 kg of CO 2 yearly. To avoid self-shading of the PV array, an appropriate inter-row distance was determined. The total quantity of PV modules and the electrical configuration of the PV array is presented. Keywords : Hybrid energy system, Net present cost, Optimal sizing and Photovoltaic

Analyzing of a Photovoltaic/Wind/Biogas/Pumped-Hydro Off-Grid Hybrid System for Rural Electrification in Sub-Saharan Africa—Case Study of Djoundé in Northern Cameroon

Traditional electrification methods, including grid extension and stand-alone diesel generators, have shown limitations to sustainability in the face of rural electrification challenges in sub-Saharan Africa (SSA), where electrification rates remain the lowest in the world. This study aims at performing a techno-economic analysis and optimization of a pumped-hydro energy storage based 100%-renewable off-grid hybrid energy system for the electrification of Djoundé, which is a small village in northern Cameroon. Hybrid Optimization of Multiple Energy Resources (HOMER) software was used as an analysis tool, and the resulting optimal system architecture included an 81.8 kW PV array and a 15 kW biogas generator, with a cost of energy (COE) and total net present cost (NPC) of €0.256/kWh and €370,426, respectively. The system showed promise given the upcoming decrease in installation cost of photovoltaic systems. It will be viable in parts of SSA region but, significant investment subsidies will be needed elsewhere. The originality of this study can be emphasized in three points: (1) the modelling with the recently introduced pumped-hydro component of HOMER; (2) broadening sensitivity analysis applications to address practical issues related to hybrid renewable energy systems (HRES); and, (3) consideration of the agricultural sector and seasonal variation in the assessment of the electricity demand in an area of SSA.

Optimally sized design of a wind/photovoltaic/fuel cell off-grid hybrid energy system by modified-gray wolf optimization algorithm

This study deals with an off-grid hybrid energy generation system composed of wind turbines, photovoltaic cells, and fuel cells to supply a specific load. The purpose is to minimize the cost of energy generation over a period of lifetime while satisfying a set of system reliability constraints in the system. The stated objective is to determine the optimal value of system components, that is, the number of wind turbines, the number and angle of photovoltaic arrays, the size of electrolyzer, hydrogen tanks, fuel cells, and DC/AC converters. The costs incorporated into this design included net present value of investment, costs of equipment, replacement and maintenance, and the costs arising from power supply interruption, all for a period of 20 years considered as the system lifetime. The data pertaining to load demand, sunlight and wind speed were considered to be known and deterministic. This design considered the failure of three main system components, namely, wind turbines, photovoltaic cells, and AC/DC converter, and incorporated a number of cost factors such as initial investment, operating and maintenance expenses, and value of lost load. The wind and solar data used in this study pertained to Ankara, Turkey. The gray wolf optimization algorithm for the first time is used to optimize such a system, and the results are compared with the ones obtained by particle swarm optimization algorithm. A new hybrid metaheuristic algorithm based on the modified-gray wolf optimization algorithm and the traditional particle swarm optimization algorithms is proposed to solve the problem. The results indicate that the gray wolf optimization algorithm achieves better optimal results in comparison to the well-known particle swarm optimization algorithm and the developed hybrid method performs better in comparison to the gray wolf optimization and particle swarm optimization algorithms for this specific optimization problem.

A Novel Off-Grid Optimal Hybrid Energy System for Rural Electrification of Tanzania Using a Closed Loop Cooled Solar System

A large proportion of the world’s populations live in developing countries. Rural areas in many of these countries are isolated geographically from grid connections and they have a very low rate of electrification. The uninterrupted power supply (UPS) in these regions is a considerable challenge. The use of renewable energy resources (RER) in an off-grid hybrid energy system can be a pathway to solving this problem. Tanzania has a very low electrification rate (rural 16.9%, urban 65.3%). This paper discussed, described, designed a novel uninterruptible, and environmental friendly solar-wind hybrid energy system (HES) for remote area of Tanzania having closed loop cooled-solar system (CLC-SS). An optimized configuration for the proposed HES was obtained by Hybrid Optimization Model for Electric Renewable (HOMER) analysis software using local solar and wind resources. The designed CLC-SS improved the efficiency of the hybrid solar-wind systems by extracting more power from the solar modules. An evaluation of CLC-SS revealed a 10.23% increase in power output from conventional solar PV modules. The results validate that the optimized system’s energy cost (COE) is 0.26 $/kWh and the net present cost (NPC) of the system is $7110.53. The enhanced output solar wind hybrid system, designed in this paper is cost-effective and can be applied easily to other regions of the world with similar climate conditions.

Optimization of 10 kW solar photovoltaic – diesel generator hybrid energy system for different load factors at Jaisalmer location of Rajasthan, India

Jaisalmer town in Rajasthan, India is having annual average solar insolation of 5.80 kWh/m2/day and 270 – 300 clear sky days in a year. A 10 kW off-grid hybrid energy system (HES) consisting of solar photovoltaic panels – diesel generator – bidirectional converter and batteries with zero percentage loss of load for Jaisalmer is designed using HOMER (version 3.4.3) software. Different system load factors of 0.33, 0.50, 0.67, 0.83 and 1 corresponding to fraction of running hours per day of the system are considered. The system is analyzed for all three aspects, namely, electrical, economic and emission point of view. Least levelized cost of electricity (LCOE) of Rs. 8.43/kWh is obtained at a load factor value of 0.5. If diesel generator alone (without Solar PV) is used to fulfil the demand for a load factor of 0.5the value of LCOE is obtained Rs.19.23/kWh. Comparison of results obtained for HES and diesel generator are made for load factor of 0.5 and 1.

Techno-economic analysis of off-grid hydrokinetic-based hybrid energy systems for onshore/remote area in South Africa

Hydrokinetic power generation is a relatively recent type of hydropower that generates electricity from kinetic energy of flowing water making the conversion process more competitive compared to traditional micro-hydropower. Few authors have already analyzed the use of standalone hydrokinetic systems for rural electrification, however, there is no available literatures investigating the possibility of using this technology in combination with other renewable energy sources or diesel generator. Therefore, the aim of this paper is to investigate the potential use of hydrokinetic-based hybrid systems for low cost and sustainable electrical energy supply to isolated load in rural South Africa where adequate water resource is available. Different hybrid system configurations are modeled and simulated using the Hybrid Optimization Model for Electric Renewable (HOMER) and the results are analyzed to select the best supply option based on the net present cost and the cost of energy produced. The simulation results from two different case studies show that hybrid systems with hydrokinetic modules incorporated in their architectures have lower net present costs as well as lower costs of energy compared to all other supply options where the hydrokinetic modules are not included.

Comparative Analysis of Hybrid GAPSO Optimization Technique With GA and PSO Methods for Cost Optimization of an Off-Grid Hybrid Energy System

In this study, a new methodology, hybrid GAPSO (HGAPSO), has been developed to design and achieve cost optimization of an off-grid hybrid energy system (HES). Since standard particle swarm optimization (PSO) algorithm suffers from premature convergence due to low diversity, and genetic algorithm (GA) suffers from a low convergence speed, in this study modification strategies have been used in GAs and PSO algorithms to achieve the properties of higher capacity of global convergence and the faster efficiency of searching. This improved algorithm HGAPSO described and implemented in a MATLAB environment has been compared with GAs and PSO algorithms in finding the optimum minimum annual cost of a real off-grid energy system (a group of villages in India). The optimization process resulted in HES, utilizing photovoltaic (PV) arrays, batteries, a diesel generator, and other renewable sources, which, in turn, may prove to be a feasible and sustainable power supply alternative for a remote unelectrified rural area. The superiority of HGAPSO algorithm over GAs and PSO algorithms for the problem at hand is shown in terms of convergence generations and computation time.

SAHPPA: a novel power pinch analysis approach for the design of off-grid hybrid energy systems

This work proposes a novel approach called stand-alone hybrid system power pinch analysis (SAHPPA), which is particularly applicable for the design of off-grid distributed energy generation systems. The enhanced graphical tool employs new ways of utilising the recently introduced demand composite curve and supply composite curve while honouring and adapting fundamental energy systems engineering concepts. The SAHPPA method is capable of optimising the capacity of both the power generators and energy storage for biomass (i.e. non-intermittent) and solar photovoltaic (i.e. intermittent) energy technologies, which is a contribution to the emerging area of power pinch analysis. In addition, the procedure considers all possible efficiency losses in the overall system encompassing the charging–discharging and current inversion processes.

Feasibility Study of Off-grid Hybrid Energy Systems for Applications in Ondo State Nigeria

Feasibility Study of Off-grid Hybrid Energy Systems for Applications in Ondo State Nigeria