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The goal of this review is to offer an all-encompassing evaluation of an integrated solar energy system within the framework of solar energy utilization. This holistic assessment encompasses photovoltaic technologies, solar thermal systems, and energy storage solutions, providing a comprehensive understanding of their interplay and significance. It emphasizes the importance of solar energy as a renewable resource and its role in addressing global energy demand and mitigating climate change. The review highlights the significance of advancements in various solar energy technologies, focusing on their environmental benefits, including greenhouse gas emissions reduction and air and water pollution mitigation. It explores the evolution of photovoltaic technologies, categorizing them into first-, second-, and third-generation photovoltaic cells, and discusses the applications of solar thermal systems such as water heaters, air heaters, and concentrators. The paper examines key advancements in energy storage solutions for solar energy, including battery-based systems, pumped hydro storage, thermal storage, and emerging technologies. It references recent published literature to present findings on energy payback time, carbon footprint, and performance metrics. Challenges to widespread adoption are discussed, including cost and economic viability, intermittency, environmental impacts, and grid integration. Strategies to overcome these challenges, such as cost reduction, policy support, energy storage integration, and sustainable practices, are presented based on published literature. By bridging gaps in existing literature, this comprehensive resource aims to equip researchers, policymakers, and industry professionals with insights into forging a sustainable and renewable energy future. [ABSTRACT FROM AUTHOR]

In this paper, stochastic synchronization of the wind and solar energy using energy storage system based on real-time pricing in the day-ahead market along with taking advantage of the potential of demand response programming has been analyzed. Since renewable energies, loads and prices are uncertain, and planning is based on real-time pricing, the optimal biding proposition considers the wind power, solar system, and energy storage system. Uncertainty is addressed to solve the bidding strategy in a day-ahead market for optimal wind and PV power and optimal charging for energy storage. Batteries are the most promising device to compensate for the fluctuations of wind and photovoltaic power plants to mitigate their uncertainty. In general, using MILP is a suitable approach to address uncertainty as long as a linear formulation is acceptable for modeling either with continuous variables or integer ones. By setting some scenarios to formulate market prices, imbalance of energy, wind and solar system, the uncertainty problems could be easily solved by MILP solver. The model created enables the retailer to realize the potentials of the demand response program and exploit high technical and economic advantages. To ensure fair prices, a set of regulating constraints is considered for sales prices imposed by the regulation committees. A model is presented to optimize the electricity trading strategy in the electricity market, considering the uncertainty in the wholesale market price and the demand level. The retailer considered in this paper is a distribution company that is the owner and operator of the networks and operates under real-time pricing regulations. To model demand response, the elasticity coefficient is used. The proposed solution is implemented on a standard 144-bus sample network using a nonlinear integer programming method. The presented method results provide helpful and valuable information based on the optimal method proposed by the retailers considering the demand response program and real-time pricing system. [ABSTRACT FROM AUTHOR]

Renewable energy attracts increasing attention from both industry and academia under the context of carbon neutrality. For wind and solar energy, the strong dependence on natural processes results in the imbalance between energy production and real demands. Energy storage technologies, e.g., Compressed Air Energy Storage (CAES), are promising solutions to increase the renewable energy penetration. However, the CAES system is a multi-component structure with multiple energy forms involved in the process subject to high temperature and high-pressure working conditions. The CAES system is a complex process flowsheet consisting of charging and discharging process. The process should be optimized to achieve the best thermodynamic and economic performance. Under the optimal design conditions, it might lead to severe consequences once a failure occurs, e.g., harm to humans, the environment, and assets. Limited attention and scarce available information have been paid to the CAES system risk management yet. Hence, this paper applies the System-Theoretic Process Analysis (STPA), which is a top-down method based on system theory, to identify the CAES system safety hazards. The results are expected to provide a preliminary guideline for practitioners regarding the safety and reliability of the CAES system. As a result, a more reliable CAES system can contribute to a more flexible energy system with more efficient and economic utilization of fluctuating renewable energy. [ABSTRACT FROM AUTHOR]

The present review paper aims to shed lights on the concept of fully green energy system which includes both the source of energy and the storage system. The objective is to propose an energy label "Green to Green" (G2G) that identifies systems involving simultaneously green source and green storage, as an efficient solution to achieve a significant reduction in the dangerous level of pollution that most countries have reached today. Green sources include mainly renewable energy systems such as solar, wind, geothermal and wave energy systems. In its turns green storage includes pumped hydroelectric, flywheel, hydrogen and compressed air. Moreover, and as a case investigation on G2G concept, the paper reviews the main solar-hydrogen coupling systems, that are categorized within four categories parabolic trough-hydrogen, solar tower-hydrogen, photovoltaic-hydrogen and solar chimney-hydrogen. • Green to Green (G2G) is presented as a label to promote pollution-free systems. • Green storage includes Hydrogen, flywheel, compressed air and pumped hydro. • As a case study on (G2G) concept, the paper highlights solar – hydrogen coupling. [ABSTRACT FROM AUTHOR]

Local energy sharing (LES) is a concept that enables sharing between distribution system participants such as consumers, producers, and prosumers at the local level in a transparent and cooperative manner. It can improve local supply-demand balancing, reduce voltage deviations, and improve social welfare. However, the feasibility of such an approach is highly dependent on the regulatory framework and implementation requires investment in an adequate information and communication infrastructure. This paper examines components for the implementation of LES within energy communities in the EU, with a focus on price-forming methods that can be integrated into a net-billing system and adopted for different regulatory set-ups. Further, a method for the assessment of impacts on market participants is provided. The approach is applied for the assessment of the opportunities for LES in the city of Križevci, considering local generation, flexibility options, and real-life regulatory requirements. It is shown that LES under appropriate regulatory provisions can be an effective market-based mechanism for stimulating local generation and flexibility activation, and that way support decarbonization and local self-sufficiency. All members can benefit from participating in the energy community, but the distribution of the benefits notably depends on the applied LES price-forming method. On the other hand, subject to regulatory setup, the trade-offs are reflected on reduced revenues for market participants that generate income based on transmission fees, taxes, and/or surcharges. • Components for local energy sharing (LES) implementation within energy communities. • Framework for feasibility evaluation of LES under different regulatory set-ups. • MILP LES market-clearing model with energy sharing compensation price method. • LES price-forming methods integrated into a net-billing system. • Simulation of LES as a market with a local energy sharing coordinator. [ABSTRACT FROM AUTHOR]

Considering the broad range of applications, efficient retrieval and storing electrical energy methods are still challenging. Besides the load variations, the ever‐increasing intermittent renewable energy penetration into the grid system has witnessed the system complexities. In off‐grid applications, energy storage can balance electricity consumption and electricity generation to avoid voltage and frequency deviations. This research paper focuses on the energy management of an off‐grid climate refuge system used for hot and arid locations with a system comparison for two routes of different storage techniques, namely flywheels and a lithium‐ion battery. The proposed system can generate its power from photovoltaics and provide cooling and other auxiliaries through vapor compression cycle and water misting units with an operation of about 16 hours (ie, from 7:00 am to 11:00 pm) on the weekdays and 12 hours on the weekends. A comparison of levelized costs is conducted for the evaluation using HOMER software. The annual energy production by solar photovoltaics for the proposed system is 20 MWh, and the annual consumption is 16 MWh. The photovoltaic‐battery storage system has shown the lowest cost of electricity, corresponding to 0.761 $/kWh, and net present cost of $66 238 and is optimum in all sensitivity analysis cases. [ABSTRACT FROM AUTHOR]

Electrical energy becomes necessary for human being. Generation of electrical energy mostly depends on fossils fuel, they are limited in nature and also responsible for environmental pollution. Renewable energy resources provides a better alternative for future,In comparison to conventional energy resources economical aspect is a major issue of renewable energy sources with the feasibility and efficiency. These limitations are tried to overcome by deployment hybrid renewable energy resources. There are certain criteria to analyze and implement the sized, optimized and cost efficient system. This paper focus on hybrid energy systems based on solar photovoltaic (PV) and wind resources. This paper shed lights on various parameters of economic feasibility, sizing strategies with logical advancements to enhance their utilization, future prospects, and their arrangement. Strategies to develop an effective storage system is also presented here.A brief review on developments in optimization techniques, reliability index and cost analyzing techniques for hybrid renewable energy systems are also presented. [ABSTRACT FROM AUTHOR]

This paper compares different strategies to transform the heating sector into a future 100% renewable energy solution. It focuses on the consequences for infrastructures in terms of grids and storage across the electricity, gas and heating sectors. The hypothesis is that these consequences are rarely taken into proper consideration, even though the costs are significant and differ substantially between the alternative pathways. While the smart grid scenarios are based on electricity as an energy carrier, the “smart energy systems” approach is based on a cross-sectoral use of all grids. Using Denmark as a case, this paper shows how the current gas and district heating grids each have twice the capacity of the electricity distribution grid. Moreover, the existing gas and thermal storage capacities are substantially higher and the additional future capacities are more affordable than within the electricity sector. The conclusion is that the “smart grid” pathway requires a 2–4 times expansion of the electricity grid and significant investments in electricity storage capacities, while the “smart energy systems” pathway can be implemented with relatively few investments in affordable minor expansions of existing grids and storage capacities. [ABSTRACT FROM AUTHOR]

This century will witness a major transformation in how energy is acquired, stored, and utilized globally. The impetus for this change comes from the deep impacts that both developed and developing societies have had on our planet's environment during the past century, and the projections going forward of what will happen if we do not act transformatively within the next 2 decades. This paper describes the basis for a meeting held in October 2018 on the need for decarbonization in our energy landscape, and specifically the status and challenges of the science that provides the foundation for such technology. Within the realm of decarbonization in energy generation lies the science of solar energy conversion using new or improved photovoltaic materials and artificial photosynthesis for water splitting and other energy-storing reactions. The intimately related issue of renewable energy storage is being addressed with new strategies, materials, and approaches under current investigation and development. The need to improve the interactions between scientists working on these connected but separately considered challenges and on the transition of scientific achievement to practical application was also addressed, with specific efforts enumerated. [ABSTRACT FROM AUTHOR]

A system for the exploitation of the available energy of the sun is proposed in this paper. The system involves a collector, a heat reservoir, a vapor generator, a set of direction control valves and a turbine. These components can be combined to form four closed different cycles in order to generate electricity or store heat according to the outdoor environment. An optimization method is proposed to optimize the energy collected at the shaft of the turbine for a given input sun power. The method establishes a functional relationship between the optimal mass flow rate through the collector, the sun input power and the optimal collected power at the shaft of the turbine. A similar functional relationship is established between the optimal temperature of the working fluid and the sun input power. The collected optimal energy is computed as a function of the sun input power for different temperatures of the vapor generator. The effect of the heat transfer coefficient and coefficient of radiation of Stefan- Boltzmann and the temperature of the vapor generator on the output optimal energy are investigated. [ABSTRACT FROM AUTHOR]

This paper proposes a multisource multiproduct framework for coupled multicarrier energy supplies with a biogas–solar–wind hybrid renewable system. In this framework, the biogas–solar–wind complementarities are fully exploited based on digesting thermodynamic effects for the synergetic interactions of electricity, gas, and heating energy flows, and a coupling matrix is formulated for the modeling of production, conversion, storage, and consumption of different energy carriers. The multienergy complementarity of biogas–solar–wind renewable portfolio can be utilized to facilitate the mitigation of renewable intermittency and the efficient utilization of batteries, and a multicarrier generation scheduling scheme is further presented to dynamically optimize dispatch factors in the coupling matrix for energy-efficient conversion and storage, while different energy demands of end-users are satisfied. The proposed methodology has been fully tested and benchmarked on a stand-alone Microgrid over a 24-h scheduling horizon. Comparative results demonstrate that the proposed scheme can lower the battery charging/discharging actions as well as the degradation cost, and also confirm its capability to accommodate high penetration of variable renewables. [ABSTRACT FROM AUTHOR]

Prince Edward Island, already with the highest wind energy penetration of any province in Canada, aims to increase its renewable energy generation. A challenge is realizing better matching of intermittent wind and solar power with on-island electricity demand. This paper provides an initial perspective by considering the case of a 100% renewable island electricity system. Using time-series power data of wind, solar, and electricity demand for the province, varying capacities of wind and solar power along with battery energy storage and biomass are considered to model 100% renewable electrical energy scenarios. Wind, solar, and storage combinations without curtailment show how complementary supply combinations can reduce seasonal variations. Scenarios including curtailment demonstrate significantly reduced storage requirements. Scenarios that include biomass suggest little benefit in combining biomass and storage. Least-cost solar, wind, and storage capacities are estimated. Potential storage cost reductions appear to be transformative in enabling greater renewable energy integration. [ABSTRACT FROM AUTHOR]

Abstract: A Hybrid Energy System may been defined as a system in which different energy sources (solar, wind, hydro, diesel generator, etc.) as well as energy storage systems are interconnected to meet the load energy demand at any time. Given that the electrical contribution of energy each sources (taking individually) is dependent on the variation of the resources (sun, wind, water), and since the load energy requirement fluctuates, the main attribute of such hybrid system is to be able to generate energy at any time by optimally using each energy source, and storing excess energy for the later use in deficit generating conditions. The induced optimization problem is to compute the optimal size and operation control of the system with the aim of minimizing its initial, operation and maintenance as well as replacement costs while responding to the load energy requirements. In this paper our goal will be to propose an approach for optimal operation control of a hybrid multisource system with the aim of meeting the load energy requirement with reliability and minimized life cycle costs. The paper will be limited at the problem formulation and the development of the mathematical model for the performance of all the hybrid system's components. The proposed hybrid system model is based on a description of current flows from the different power sources, taking into account the losses and the impact of the operating decisions along the way up to the loads. The decision variables include the renewable energy sources sizes and number of modules as well as the operation control settings and strategies which lead to the determination the diesel generator and battery system output power. These developed model's decision variables can then be optimized using any suitable advanced algorithm in such a way to minimize the life-cycle costs subject while satisfying demand. [Copyright &y& Elsevier]

This contribution studies the usability of aquifer thermal energy storage (ATES) for seasonal solar heat storage by means of thermo-hydraulic modeling. The geological setting refers to the North East German Basin (NEGB), specifically a site approx. 50 km west of Berlin, Germany. The considered storage formation is located in Jurassic sandstones at about 270 m depth below surface, showing an in-situ (undisturbed) formation temperature of around 17 °C and appropriate hydraulic storage properties. The paper considers idealised doublet systems in faulted as well as unfaulted reservoir domains and studies the energy- and mass transport of simulated ATES systems. Five perennial loading/unloading series of solar thermal energy are investigated, assumed to be harvested by a hectare-sized flat plate collector field which is modeled employing climate data of the considered region. The simulation results exemplarily show how the storage system develops temperature-conserving recovery fractions of up to 80% heat recovery during the first years of operation. [ABSTRACT FROM AUTHOR]

Household renewable energy generation through the use of solar panels is becoming more commonplace as the installation cost is reducing and electricity prices are rising. Solar energy is an intermittent source, only generated during the day subject to interference from weather and seasonal variation. Energy storage solutions such as Lithium Ion batteries are also reducing is cost and have become a viable solution for storing the solar energy generated for use at other times. In this paper we discuss the feasibility and limitations of various renewable energy, energy storage, feed into grid and off the grid systems. We also explore the results of our case study, The University of Western Australia׳s Future Farm, which featured a 10 kW solar system with 20 kWh battery storage, off the grid. Finally we use West Australians daily energy usage information to model the energy and savings of installing solar panels, home energy storage and using an electric vehicle. [ABSTRACT FROM AUTHOR]

The paper aims to demonstrate the improvement of power dispatchability that can be achieved with a suitable integration of Concentrating Solar Power (CSP) and Concentrating Photovoltaic (CPV) plants to mitigate the effects of the variability and intermittency of solar energy. In particular, the CSP–CPV plant analyzed here refers to the design data of the Ottana Solar Facility, which is currently under construction in the industrial district of Ottana (Sardinia, Italy). Since it is very difficult to know the power curves that are going to be required during the operation phases of the hybrid CSP–CPV plant, the present study has been carried out by assuming a reference daily power output curve, which is simply represented by a constant power output. Moreover, two different energy management strategies, fully integrated (F-INT) and partially integrated (P-INT), are analyzed and compared. The results of this study show the advantages of using an integrated management strategy to satisfy a constant power output curve. Optimization of the CSP and CPV power share leads to an effective use of the dispatch capabilities of the CSP plant owing to the TES section, while the CPV plant is fully exploited, especially during the hours of high solar radiation. Comparison of the results achieved with the F-INT and P-INT control strategies demonstrates that the F-INT one leads to better performance both in terms of annual energy production and hours of potential time duration. [ABSTRACT FROM AUTHOR]

One of the main advantages of solar photovoltaic (PV) energy is its availability during periods of high electricity demand, namely hot, sunny days. Unfortunately, the daily energy peak of a south-facing solar panel, oriented to maximize energy production, rarely coincides with the actual peak in electricity demand, which is usually in the late afternoon or evening. Using the Province of Ontario, Canada, as a case study, this paper evaluates three strategies for improving the correlation between PV energy production and electricity demand: optimally orienting PV modules, combining geographically dispersed arrays, and using a simple energy storage system. The strategies are compared based on their ability to improve the supply-demand correlation, their relative cost of energy, and the capacity credit of each strategy. We find that optimally orienting multiple modules in an array offers little potential to improve correlation, while the cost of energy increases between 30 and 40%. Geographically dispersed PV arrays and energy storage offer a better approach to improving the correlation between PV production and electricity demand. [ABSTRACT FROM AUTHOR]

The current editorial summarized some of the scientific works presented in the Sustainable Energy and Environmental Protection (SEEP) conference-held at the University of the West of Scotland, UK, 2018. The selected work was directly related to the scope of the Renewable, Sustainable Energy Reviews (RSER) journal. During the conference activities, experts from all around the world in the subjects of: renewable energy, climate change, optimization, and economics presented and discussed the progress made in renewable energy sources, as well as the new strategies for protecting the environment from the hazards connected with fossil fuel utilization. The methods presented in the conference focused on several directions: the development of efficient energy conversion systems with low/no environmental impacts; the suggested policies to widespread renewable energies; the restriction in the emission of greenhouse gases, and the recent progresses in CO 2 capture. This editorial focused on the renewable energy developments and their positive effect on the climate change, and briefly summarized the accepted manuscripts in this issue. • Effects of renewable energy on climate change. • Background on the International Conference on Sustainable Energy and Environmental Protection SEEP. • Summary of selected papers of SEEP 2018. [ABSTRACT FROM AUTHOR]

The current editorial summarized some of the scientific works presented in the Sustainable Energy and Environmental Protection (SEEP) conference-held at the University of the West of Scotland, UK, 2018. The selected work was directly related to the scope of the Renewable, Sustainable Energy Reviews (RSER) journal. During the conference activities, experts from all around the world in the subjects of: renewable energy, climate change, optimization, and economics presented and discussed the progress made in renewable energy sources, as well as the new strategies for protecting the environment from the hazards connected with fossil fuel utilization. The methods presented in the conference focused on several directions: the development of efficient energy conversion systems with low/no environmental impacts; the suggested policies to widespread renewable energies; the restriction in the emission of greenhouse gases, and the recent progresses in CO 2 capture. This editorial focused on the renewable energy developments and their positive effect on the climate change, and briefly summarized the accepted manuscripts in this issue. • Effects of renewable energy on climate change. • Background on the International Conference on Sustainable Energy and Environmental Protection SEEP. • Summary of selected papers of SEEP 2018. [ABSTRACT FROM AUTHOR]

Rather than using individually distributed energy storage frameworks, shared energy storage is being exploited because of its low cost and high efficiency. However, proper sizing and operations approaches are still required to take advantage of shared energy storage in distribution networks. This paper proposes a bi-level model to optimize the size and operations of shared energy storage in hybrid renewable-resource power generation systems. The upper-level model maximizes the benefits of sharing energy storage for the involved stakeholders (transmission and distribution system operators, shared energy storage operators and the various power plant owners) and the lower-level model minimizes the hybrid system operating costs. The benefits of this system were found to be: (1) reductions in wind and solar power curtailment and coal-fired generation costs; (2) peak shaving; (3) frequency regulation; and (4) a deferral of upgrades to power transmission and distribution facilities. To fully realize the long-term planning and short-term operational interactions of shared energy storage, a bi-level nested genetic algorithm was designed to solve the proposed model. By continuously updating the solutions, a set of optimal solutions were generated. To validate the approach, numerical tests were conducted, with the results showing that by properly sizing and operating the shared energy storage in distribution networks, the wind curtailment rate was reduced by about 10.2%, the solar curtailment rate was reduced by 14.2%, and the stakeholder benefits were around 154 million dollars. Further discussion is given on the benefits of shared energy storage investments. • Shared energy storage is planned and modelled in distribution networks. • A bi-level model is established for shared energy storage sizing and operation. • An interactive bi-level nested genetic algorithm is designed. • A comparative analysis is conducted to validate the shared energy storage feasibility. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: NZEB (Net zero energy building) is regarded as an integrated solution to address problems of energy-saving, environmental protection, and CO2 emission reduction in the building section. NZEB could be even possible with electricity production if enough renewable energy could be used. Moreover, various building-service systems with renewable energy sources have been widely considered for potential applications in NZEB. All of these new features extend the technical boundary of the conventional energy-efficient buildings, attach a more profound implication to the sustainable development of building technology, and therefore pose a challenge to evaluation works on NZEB performance. This paper presents a guided tour on NZEB evaluation through literature-research. An overview about definitions and energy-efficient measures of NZEB is presented so that the research object and technology boundary can be clarified for NZEB evaluation. Then, a summary of widely-used research method, tool and performance indicator in evaluation is provided for the methodology part. This part also includes a discussion on the application of LCA (life cycle assessment) in NZEB evaluation and LCA's role in promoting a well-defined NZEB. Finally, potential progress in NZEB evaluation with possible development trends is highlighted in terms of energy storage, load match and smart grid. [Copyright &y& Elsevier]

Abstract: The unevenness of solar photovoltaic energy output poses a number of issues that reduce its capability to be considered a reliable substitute for fossil fuels. For instance, solar photovoltaic plants convert and inject energy in the grid during the daytime, but fail to do so during bad weather conditions or at night. Variable weather conditions also render a reliable energy injection planning impossible, causing the photovoltaic power plant output to be most often unpredictable. Furthermore, all the energy converted and immediately injected in the grid poses the risk of creating imbalances in the electric energy distribution lines. A nation-wide energy system characterized by a large penetration of photovoltaic and wind energy sources can therefore be extremely difficult to manage and cannot be considered dependable. The core issue is how to improve the reliability of electricity production from such renewable energy sources. One way to tackle such unpredictability is to add an energy storage system. Many storage technologies are already available, although none of them has stood out to be the one and only answer to the problem. Different specific conditions require different storage technologies, and this is why that a combination of different solutions, rather than a single one, can be the right approach to storing energy. In this paper, a hydrogen energy storage system has been designed and simulated using real-life data taken from a PV plant of 1616.8 kWp successfully operating in central Italy. The aim is to understand the main operating conditions and the financial feasibility for infrastructure institutional investors to deploy hydrogen storage technology. The results show that such system is capable of guaranteeing a reliable energy injection in the grid, making the photovoltaic power plant as dependable as traditional fossil-fuel power plants. The advantages of such substitution are numerous: sizable decreases in green-house or toxic gases and pollutants, healthier environment, total energy independence from foreign energy fuel imports, local job creations, just to name a few. [Copyright &y& Elsevier]

Abstract: With the growing amount of decentralized power production the design and operation of the grid has to be reconsidered. New problems include the two-way flow of electricity and maintaining the power balance given the increased amount of uncertain and fluctuating renewable energy sources like wind and solar that deliver electricity to the grid. Solution directions are the development of smart grids, demand side management, virtual power plants and storage of electricity. These are directions that, rightly so, are already attracting a lot of attention and R&D funding. In this paper critical issues are identified and specified. However, we will also explore new solution directions based on an integrative approach as proposed by the Dutch Royal Academy of Science foresight committee on renewable energy conversions. These alternative solutions include flexible coproduction and local production of chemicals and fuel that can also fulfill a storage function. [Copyright &y& Elsevier]

Abstract: This paper analyses the hybrid solar and hydro (SHE) system as a unique technological concept of the sustainable energy system that can provide continuous electric power and energy supply to its consumers and the possibilities of its implementation in Europe and areas with similar climate. The sustainability of such system is based on solar photovoltaic (PV) and hydroelectric (HE) energy as renewable energy sources (RES). For the purpose of connecting all relevant values into one integral SHE system, a mathematical model was developed for selecting the optimal size of the PV power plant as the key element for estimating the technological feasibility of the overall solution. Sensitivity analysis (parameter analysis) was made for the model, where local climate parameters were varied: solar radiation, air temperature, reservoir volume, total head, precipitation, evaporation and natural water inflow. It has been established that, apart from total head (which is to be expected), solar radiation, hydro accumulation size and natural water inflow have the biggest effect on the calculated power of the PV power plant. The obtained results clearly show a wide range of implementation of the new energy source (SHE system), i.e. from relatively cold climates to those abundant in solar energy, but also with relatively small quantity of water, because it only recirculates within the system. All this points to the necessity for further development of hybrid systems (RES+HE systems) and to the fact that they could play an important role in achieving climate objectives. [Copyright &y& Elsevier]

Abstract: Hydrogen as an energy currency, carrier and storage medium may be a key component of the solution to problems of global warming, poor air quality and dwindling reserves of liquid hydrocarbon fuels. Hydrogen is a flexible storage medium and can be generated by the electrolysis of water. It is particularly advantageous if an electrolyser may be simply and efficiently coupled to a source of renewable electrical energy. This paper examines direct coupling of a polymer electrolyte membrane (PEM) electrolyser to a matched solar photovoltaic (PV) source for hydrogen generation and storage. Such direct coupling with minimum interfacing electronics would lead to substantial cost reduction and thereby enhance the economic viability of solar-hydrogen systems. The electrolyser is designed for fail-safe operation with multiple levels of safety and operational redundancy. A control system in the electrolyser unit provides for disconnection when required and for auto-start in the morning and auto shut-down at night, simultaneously addressing the goals of minimum energy loss and maximum safety. The PV system is a 2.4kW array (20.4m2 total area) comprising 30, 12V, 80W, Solarex polycrystalline modules in a series–parallel configuration. The integrated system has been operated for approximately 60 days over a 4-month period from September 2007 to January 2008 with many periods of unattended operation for multiple days, experiencing weather ranging from hot and sunny (above 40°C) to cool and cloudy. The principle and practicality of direct coupling of a suitably matched PV array and PEM electrolyser have been successfully demonstrated. Details of electrolyser operation coupled to a PV array along with modelling work to match current–voltage characteristics of the electrolyser and PV system are described. [Copyright &y& Elsevier]

Energy storage is an enabling technology for power system integration of renewable sources, while data storage enables computer system integration. In this paper, a functional analogy relating energy and data storage is derived. Battery or hydrogen storage can provide large energy capacity similar to a hard disk providing large data capacity. Supercapacitors or flywheels provide fast and frequent access to cache energy similar to the computer's RAM providing fast and frequent access to data. In analogy to computer engineering, a cache control that coordinates the operation of a multilevel storage consisting of such complementary capacity and access-oriented storage technologies is designed. It is illustrated how for an industrial distributed energy system with renewable generation, local load, fueling station, and connections to the electricity and gas distribution networks, the cache control provides energy management to support a modular plug-and-play-like system integration. The benefit of the analogy in education is evaluated on a representative sample of electrical engineering students at the University of Washington. While familiar with computing, students do not typically have the same level of exposure to power engineering. The understanding of distributed energy systems concepts is shown to improve thanks to this bridging analogy between computer and power engineering. [ABSTRACT FROM AUTHOR]

Energy storage systems (ESS) are becoming essential as a solution for troublesome industrial systems. This study focuses on the application of a type of ESS, a high-power technology known in the literature as supercapacitors or electric double layer capacitors (EDLC). This technology has had a huge impact during the last decade on research related to the electric traction drives, renewable sources and powergrids. Related to this aspect, this paper summarizes the most relevant scientific publications in the last five years that study the use of supercapacitor technology (SCs) in electric traction applications (drives for rail vehicles and drives for road vehicles), generation systems for renewable energy (wind, solar and wave energy), and connection systems to the electric grid (voltage and frequency regulation and microgrids). The technology based on EDLC and the practical aspects that must be taken into account in the op-eration of these systems in industrial applications are briefly described. For each of the aforementioned applications, it is described how the problems are solved by using the energy storage technology, drawing the solutions proposed by different authors. Special attention is paid to the control strategies when combining SCs with other technologies, such as batteries. As a summary, some conclusions are collected drawn from the publications analyzed, evaluating the aspects in which it is necessary to conduct further research in order to facilitate the integration of EDLC technology. [ABSTRACT FROM AUTHOR]

Sources such as solar and wind energy are intermittent, and this is seen as a barrier to their wide utilization. The increasing grid integration of intermittent renewable energy sources generation significantly changes the scenario of distribution grid operations. Such operational challenges are minimized by the incorporation of the energy storage system, which plays an important role in improving the stability and the reliability of the grid. This study provides the review of the state-of-the-art in the literature on the economic analysis of battery energy storage systems. The paper makes evident the growing interest of batteries as energy storage systems to improve techno-economic viability of renewable energy systems; provides a comprehensive overview of key methodological possibilities for researchers interested in economic analysis of battery energy storage systems; indicates the need to use adequate economic indicators for investment decisions; and identifies key research topics of the analyzed literature: (i) photovoltaic systems with battery energy storage systems for residential areas, (ii) comparison between energy storage technologies, (iii) power quality improvement. The last key contribution is the proposed research agenda. [ABSTRACT FROM AUTHOR]

• A novel multi-objective optimization model is proposed for a biogas-solar-wind IES. • A multitasking multi-objective optimization algorithm, MO-MFEA-II, is proposed. • Digester heating is applied to improve the efficiency of biogas production. • Online parameter estimation technology is used to boost the efficacy of MO-MFEA-II. The optimal operation of integrated energy systems (IESs) is of great significance to facilitate the penetration of distributed generators and improve its overall efficiency. A grid-connected IES is proposed in this paper for the synergetic interactions of electricity, thermal and gas energy flows, in which the biogas-solar-wind complementarities are fully considered and the digester heating is applied to provide an appropriate temperature for biogas production from anaerobic digestion. Its multi-objective optimization (MOO) model is constructed to optimize the operational cost, carbon dioxide emission and energy loss while considering digesting thermodynamic effects for anaerobic digester and uncertainty of wind and solar power, which is then compared to that of a natural gas-solar-wind IES. Thereafter, we develop an improved realization of multitasking paradigm within the domain of MOO to simultaneously solve the multi-objective operation optimization of the two IESs. In the associated multitasking algorithm, the underlying similarities of distinct optimization tasks are learned online to mitigate the harmful inter-task interactions and thereby facilitate improved convergence characteristics. The efficacy of the proposed multitasking algorithm has been comprehensively assessed on a novel biogas-solar-wind IES and a natural gas-solar-wind IES. Simulation results validated that the proposed IES can be operated in a more cost-efficient and environmentally friendly manner by comparing to the natural gas-solar-wind IES; the developed multitasking MOO algorithm can provide a better performance than other state-of-art multitask and single-task optimization algorithms. [ABSTRACT FROM AUTHOR]

• Mechanical energy storage systems are very efficient in overcoming the intermittent aspect of renewable sources. • Flywheel, pumped hydro and compressed air are investigated as mechanical energy storage. • Parameters that affect the coupling of mechanical storage systems with solar and wind energies are studied. Mechanical energy storage systems are among the most efficient and sustainable energy storage systems. There are three main types of mechanical energy storage systems; flywheel, pumped hydro and compressed air. This paper discusses the recent advances of mechanical energy storage systems coupled with wind and solar energies in terms of their utilization. It also discusses the advances and evolution in each type and compares them in terms of performance, capacity, response and utilizations. The reviewed studies exhibit all parameters that affect the performance of each storage type in which the configuration of the system has the major effective role. Choosing the suitable mechanical storage type depends on the requirements of each application such as using the flywheel for short duration applications. If long duration is needed, then it is preferred to use either pumped hydro or compressed air storage systems, knowing that the former has higher efficiency while the latter provides a faster start up. For the sake of the environment, it is recommended to use the adiabatic or isothermal compressed air storage. In all cases that combine MESSs with solar or wind energy, the series connection is preferred in order to provide stability and better control strategy. [ABSTRACT FROM AUTHOR]

In developing countries such as in Africa, rural areas are not always connected to the national or regional electric grid. As there is a huge potential for solar energy production, photovoltaics are established to supply electricity for operating critical infrastructures with battery systems and diesel generators installed for redundancy. These systems have the potential for further utilization. As a first step, overproduction of solar energy is offered to households due to simple control rules observing battery levels. This paper proposes an optimization method for energy allocation by process graphs or P-graphs. The method provides preliminary estimations on optimal periodical energy balances between energy producers, storage, and consumers of different priorities. These preliminary estimations serve as reconciliation parameters for advanced real-time control of energy distribution. Each step of transforming the practical problem of multiperiod energy distribution to the language of process network synthesis and then optionally to mathematical programming is detailed. To represent the problem adequately, the original formulation of process network synthesis is extended to take into account potential targets and intermediate entities that cannot be accumulated. The work aims to provide better utilization of renewable energy sources and storage. The microgrid profit and return of investment can also be improved by the proposed methodology. Image 1 [ABSTRACT FROM AUTHOR]

Solar energy is a renewable energy source that can be utilized for different applications in today's world. The effective use of solar energy requires a storage medium that can facilitate the storage of excess energy, and then supply this stored energy when it is needed. An effective method of storing thermal energy from solar is through the use of phase change materials (PCMs). PCMs are isothermal in nature, and thus offer higher density energy storage and the ability to operate in a variable range of temperature conditions. This article provides a comprehensive review of the application of PCMs for solar energy use and storage such as for solar power generation, water heating systems, solar cookers, and solar dryers. This paper will benefit the researcher in conducting further research on solar power generation, water heating system, solar cookers, and solar dryers using PCMs for commercial development. [ABSTRACT FROM AUTHOR]

Energy crisis and environmental pollution have become global problems, and the increasing use of energy has caused climate change. Electric vehicle (EV) is regarded as the future of the automotive industry, because of the lesser impact on the environment than traditional vehicles. In recent years, electric vehicles have developed rapidly. However, the development of charging points and service cannot adapt to the development trend of EV. In urban areas, the distribution characteristics of street lighting and charging points are similar. Therefore, the street lighting pole with EV charging is proposed. However, due to the capacity limit of public grid, the single hybrid pole is only suitable for slow charging. This paper proposes hybrid poles group based on renewable energy, street lighting, and EV charging, which can realize fast charging and slow charging based on DC micro-grid with help of energy storage device. For studying the suitable number in a group of smart hybrid pole, the efficiency model of smart hybrid poles group is proposed. The efficiency model indicates that the group approach has better performance than the single pole, which provides a theoretical basis for practical construction. [ABSTRACT FROM AUTHOR]