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Storage systems and demand-response programs will play a vital role in future energy systems. Batteries, hydrogen or pumped hydro storage systems can be combined to form hybrid storage facilities to not only manage the intermittent behavior of renewable sources, but also to store surplus renewable energy in a practice known as 'green' storage. On the other hand, demand-response programs are devoted to encouraging a more active participation of consumers by pursuing a more efficient operation of the system. In this context, proper scheduling tools able to coordinate different storage systems and demand-response programs are essential. This paper presents a stochastic mixed-integer-lineal-logical framework for optimal scheduling of isolated microgrids. In contrast to other works, the present model includes a logical-based formulation to explicitly coordinate batteries and pumped hydro storage units. A case study on a benchmark isolated microgrid serves to validate the developed optimization model and analyze the effect of applying demand-response premises in microgrid operation. The results demonstrate the usefulness of the developed method, and it is found that operation cost and fuel consumption can be reduced by ~38% and ~82% by applying demand-response initiatives. [ABSTRACT FROM AUTHOR]

• Classified sales channels for different quality renewable energy. • Dynamic assessment indicators for the renewable energy's power deviation. • Power curve optimization strategy considers the self-owned battery. • Accurately and timely transmit the peak shaving pressure. • Guarantee the independent decision-making power of new energy stations. By the end of 2023, the installed capacity of renewable energy (RE) in China accounted for 36.0% of the total installed capacity, while the installed capacity of conventional thermal power units had decreased from 64.0% in 2016 to 47.6% in 2023. RE accounts for a higher proportion, leading to a shortage of peak shaving resources (PSR). As a result, the current RE quota system becomes unsustainable. In this paper, RE stations can classify their electricity into high-quality and low-quality parts based on the accuracy of their power curves. High-quality RE will be fully purchased and under stricter assessment, while low-quality RE will compete for clearing in the intraday spot market. Firstly, the article estimates the degree of PSR shortages in different periods based on technical parameters of thermal units, RE forecast information, and load forecast information. Consequently, the PSR supply capacity (PSR supply capacity) can be divided into PSR shortage status and sufficient status. Secondly, a clearing method for low-quality RE in the spot market is designed. The grid can set different PSR supply capacitys for different time periods according to the degree of PSR shortage. The assessment indicator values vary under different PSR supply capacitys. Lastly, based on the classification sales channels, this paper proposes a power curve optimization strategy that considers self-owned battery energy storage (BES). Case studies show that the proposed classification sales channels can effectively decrease the degree of PSR shortage while taking into account the benefits of RE station. The designed PSR supply capacity dividing method can accurately reflect the degree of PSR shortage in real-time, and the proposed power curve optimization strategy can further enhance the economic benefits of RE station. © 2017 Elsevier Inc. All rights reserved. [ABSTRACT FROM AUTHOR]

Given the increasing complexity and scale of power networks, the probability of system collapse has dramatically increased during natural disasters and malicious cyber attacks. The results of recent studies indicate the state-of-the-art solution to overcome these challenges is to partition existing power networks into several interconnected areas. To address this open problem, this paper presents a unified decision-making structure that consists of network partitioning and optimal operational planning issues. Unlike conventional partitioning mechanisms that overlook the physical characteristics of power grids, the proposed structure attempts to decompose the integrated power network into the optimal number of robust partitions by using the electrical modularity and electrical coupling strength (ECS) indicators. The partitioning mechanism is accomplished in line with an optimization problem to construct supply-sufficient partitions with the aim of increasing hosting capacity of renewable generation in partitioned areas and decreasing the exchanged power between available partitions. To this end, an operational planning problem is performed to determine the optimal allocation of wind farms (WFs), photovoltaic (PV) parks, and energy storage systems (ESSs) in each created partition. The proposed structure ensures the uniform distribution of renewable generation in the partitioned power networks. The presented partitioning and planning problem is applied to the IEEE 30-bus test system, and it is solved using GAMS software. The advantage of the proposed structure is demonstrated using a set of case studies. To assure precise performance assessment, optimization outputs are further analyzed by DIgSILENT PowerFactory for detailed monitoring of the effectiveness of the proposed structure under normal and emergency conditions. [ABSTRACT FROM AUTHOR]

In this paper, we argue that some businesses, such as utility companies, have responsibilities above and beyond those expounded by Friedman's analysis. Namely, certain companies are in positions that require adopting particular innovative strategies and innovative solutions that serve efficiencies that benefit their customer base and the environment. In doing so, we assess quality management principles and argue that CLEP is an example of an innovative rate design that lowers CO2 byproduct, reduces the cost for utilities by rendering peaking plants obsolete, and gives ratepayers an accurate reflection of the cost-of-energy. [ABSTRACT FROM AUTHOR]

This paper assesses the contribution of a controllable load (a reverse osmosis [RO] seawater desalination plant), together with an energy storage system in Porto Santo's small islanded electric power system. The controllable load and storage system are used to (i) smooth the net‐demand fluctuations and adapt it to the availability of renewable energy sources (RES), thus avoiding possible curtailments and contributing to a higher dissemination of RES, (ii) minimize the overall operational cost associated with the production of electricity and potable‐water, and (iii) reduce the environmental pollutants associated with the electric power systems on the island. The nonlinear nature of the problem makes it difficult to quickly obtain a robust solution through conventional mathematical tools. Therefore, an evolutionary algorithm is developed to find feasible solutions for dispatching the resources for a one‐week simulation period. The proposed algorithm determined the power output of the conventional thermal power plant, the RO desalination plant operating periods, and the storage charging and discharging periods and powers. In the proposed scenario, through a seven‐day simulation, 50% of the demand is supplied by renewable sources. The numerical results illustrate a reduction in the average total electricity‐peak demand of the island. The obtained diagrams are compared with the data gathered on Porto Santo's energy system. They display that the proposed solution is economically beneficial for the management of the electric power grid of the island of Porto Santo, while reducing the global warming potential (GWP) of the electric power system. Furthermore, it reveals that in a scenario with 50% penetration of renewable sources, through the proposed solution, a more efficient and predictable operation of the conventional electricity generators and the RO desalination plants can be achieved. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In this paper, we study the interactions among interconnected autonomous microgrids, and develop a joint energy trading and scheduling strategy. Each interconnected microgrid not only schedules its local power supply and demand, but also trades energy with other microgrids in a distribution network. Specifically, microgrids with excessive renewable generations can trade with other microgrids in deficit of power supplies for mutual benefits. Since interconnected microgrids operate autonomously, they aim to optimize their own performance and expect to gain benefits through energy trading. We design an incentive mechanism using Nash bargaining theory to encourage proactive energy trading and fair benefit sharing. We solve the bargaining problem by decomposing it into two sequential problems on social cost minimization and trading benefit sharing, respectively. For practical implementation, we propose a decentralized solution method with minimum information exchange overhead. Numerical studies based on realistic data demonstrate that the total cost of the interconnected-microgrids operation can be reduced by up to 13.2% through energy trading, and an individual participating microgrid can achieve up to 29.4% reduction in its cost through energy trading. [ABSTRACT FROM AUTHOR]

This paper deals with the development and experimental validation of a unified power converter for application in dc microgrids, contemplating the inclusion of solar photovoltaic (PV) panels and energy storage systems (ESS), namely batteries. Considering the limitations presented by the current structure of the power grid, mostly highlighted by the accentuated integration of emerging technologies (ESS, renewables, electric vehicles, and electrical appliances that natively operate in dc), it is extremely pertinent to adopt new topologies, architectures, and paradigms. In particular, decentralized power systems, unified topologies, and correspondent control algorithms are representative of a new trend towards a reduction in the number of power converters. Thus, the developed solution is designed to operaSAVE-15te at a nominal power of 3.6 kW, with a switching frequency of 100 kHz, and in four operation modes concerning power flow: (i) solar PV panels to batteries (PV2B); (ii) solar PV panels to dc grid (PV2G); (iii) batteries to dc grid (B2G); (iv) dc grid to batteries (G2B). Moreover, a dual active bridge converter guarantees galvanic isolation, while two back-end dc–dc converters are responsible for interfacing solar PV panels and batteries. The experimental validation of the proposed unified power converter proves its application value to self-consumption production units. [ABSTRACT FROM AUTHOR]

The global energy situation requires the efficient use of resources and the development of new materials and processes for meeting current energy demand. Traditional materials have been explored to large extent for use in energy saving and storage devices. Graphene, being a path-breaking discovery of the present era, has become one of the most-researched materials due to its fascinating properties, such as high tensile strength, half-integer quantum Hall effect and excellent electrical/thermal conductivity. This paper presents an in-depth review on the exploration of deploying diverse derivatives and morphologies of graphene in various energy-saving and environmentally friendly applications. Use of graphene in lubricants has resulted in improvements to anti-wear characteristics and reduced frictional losses. This comprehensive survey facilitates the researchers in selecting the appropriate graphene derivative(s) and their compatibility with various materials to fabricate high-performance composites for usage in solar cells, fuel cells, supercapacitor applications, rechargeable batteries and automotive sectors. [ABSTRACT FROM AUTHOR]

Global energy demand is continuously increasing where the pollution and harmful greenhouse gases that originated from the burning of fossil fuels are alarming. Various policies, targets, and strategies are being set to the carbon footprint. Renewable energy penetration into the utility grid, as well as bidirectional power flow between generation and end-users, are also potentials. A microgrid energy system can help distribute energy from intermittent renewable generation centres to load centres more effectively. The microgrid system efficiently utilises electricity from renewable sources, such as solar, wind, hydro, geothermal, and biomass. The potential renewable transition opens up a lot of possibilities for microgrids that are both grid-connected and islanded. Digital technology, specialised energy measurement devices, a fast and efficient communication system, energy storage systems, and dynamic control techniques are all used. The renewable-based microgrid system faces numerous techno-economical vulnerabilities due to the volatile and environmental dependencies of renewable energy. The complex power converter stages, lack of strict regulatory rules, grid operations and management, communications between the centralised and decentralised controllers come into play while investigating the microgrid system. This paper focuses on the prospects of renewable-based microgrid system implementation in Bangladesh. The major challenges and solutions to those challenges are described with all the current breakthroughs across the world to solve some core issues regarding microgrid planning, controlling, maintenance, resilience, and economics. [ABSTRACT FROM AUTHOR]

The loss of distribution networks caused by various electrical motors including transformers and generators can significantly affect the efficiency and economical operation of the power grid, especially for new power systems with high penetration of renewable energies. In this paper, the potential of using an energy storage system (ESS) for loss reduction is investigated, where a novel two-stage method for key-bus selection and ESS scheduling is proposed. At the first stage, the most sensitive key buses to the variation of load are selected by using the loss sensitive factors (LSF) method. At the second stage, ESS scheduling is conducted by solving an optimization problem with uncertainties caused by high penetration of renewable energies, where the uncertainties are characterized by confidence levels. The optimal scheduling of ESS including locations, capacities, and working modes are obtained at the second stage. The effectiveness of the proposed method is demonstrated via numerical simulations. The influences of capacities of ESS and confidence levels with respect to uncertainties are also analyzed. It is demonstrated that the loss-reduction performances can be improved if the ESSs are deployed on the buses selected by the LSF method and operated under the developed optimal scheduling method. [ABSTRACT FROM AUTHOR]

The grid energy storage systems, particularly renewable energy storage, are increasingly becoming more common. Thus, identifying and evaluating possible hazards and consequences are of utmost priority. This paper focuses on five energy storage systems, compressed air energy storage system, liquid air energy storage system, thermal energy storage in concentrated solar power plant, lithium-ion battery and flywheel energy storage system. The description of these systems is followed by a fundamental event tree analysis of a single most hazardous initiating event within the system. The installed safety barriers are assumed for event tree analysis based on relevant data and consequences analyzed. The failure on-demand and reliability are the two pathways for each installed safety barrier system. The analysis provides insight into worst-case scenarios and guides designers in considering the inherently safer design and redundant safety installations. However, further research is needed for accurate probabilistic calculation results based on actual failure on-demand rates obtained from industry-specific data of these instruments. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates the operation of various optimised AC‐coupled hybrid power systems for an isolated community in South Australia. In addition to diesel generators, various combinations of distributed generators and storage technologies are considered to form different hybrid power systems. Optimal design of the hybrid power systems is implemented using particle swarm optimisation (PSO) algorithm. The performance of the PSO in optimizing the above hybrid systems is discussed in detail. Whilst meeting the power system operational constraints, the minimum levelised cost of electricity (LCOE) of all systems, with various combinations of system components, are calculated. Simulation results obtained for each optimized system are carefully described and analysed. The annual operations of various components in each system are then compared and discussed in detail. A sensitivity analysis by varying the cost of wind turbines and the photovoltaic is also conducted for all hybrid systems. It has been found that the inclusion of energy storage systems (battery and flywheel) can reduce the LCOE and CO2 emission significantly compared to the inclusion of renewable generations (solar and wind) alone. The diesel‐wind‐solar‐battery system is the eco‐friendliest with an annual CO2 emission of 451 t compared to the reference diesel system (1064 t). In addition, the hybrid system consisting of diesel, wind, solar, battery and flywheel is found to be the most economic with a LCOE of 58.94 ¢/kWh compared to the diesel system with a LCOE of 67.17 ¢/kWh. [ABSTRACT FROM AUTHOR]

Summary: Climate change is one of the grand global challenges facing the world community. With the global warming threat and the attendant public health risks caused by poor air quality and harmful fine particles, the two different energy sources—nuclear and renewables—may have found a common ground and thread to form an alliance to meet these grand global challenges. The latest advent of technologies enables load‐follow flexibility of nuclear power, which has mainly provided baseload power, making nuclear energy an ideal partner for renewable energy, leveling the uncertainty and accommodating the unpredictability associated with renewables. The progress in small modular reactor (SMR) technology, which can be deployed to remote areas, can further facilitate the linking of the two energy resources. Some investigators have recently pioneered the ideas to inosculate these two energy resources with the aid of energy storage devices. This paper presents a series of case studies on meeting demand forecasts by coupling nuclear and renewable energy resources for various practical scenarios. The paper also proposes a paradigm shift in thinking in order to eliminate (or minimize to a certain extend) the need for energy storage devices in the combined energy production system by replacing the energy storage devices with some industrial facilities to directly utilize any excess power supplied by renewable energy. As an example, a desalination facility appended to the nuclear‐renewable integrated system is shown to absorb surplus power from renewable energy to produce water, thereby satisfying the demand for both power and water in a typical small remote village. Case studies are also performed to extend the concept to include the effect of weather condition and seasonal variation in solar energy conditions. The promising role of disruptive emerging technologies in the nuclear‐renewable combined system is also addressed. [ABSTRACT FROM AUTHOR]

Pipeline energy storage in district heating systems (DHSs) has great potential to improve electricity–heat coordination and promote the accommodation of renewables in power systems. However, under a decentralized operation scheme, the DHS operator may not have the motivation to utilize pipeline energy storage because it will lead to a rise in temperature and thus increase the system's overall heat loss. To address this challenge, this paper proposes a decentralized electricity–heat coordination framework by sharing part of the benefits of renewables accommodation from a power system to a DHS. A bilevel mathematical model is proposed for a policy designer to evaluate the effects of the proposed framework and determine the best sharing ratio between the two systems. An end-to-end DHS model is developed and used in the bilevel programming to consider pipeline energy storage with an explicit relationship between heat generation and demand. Finally, a case study justifies the effectiveness of the decentralized framework and proves that its performance is almost identical to the centralized power and heat dispatch framework. [ABSTRACT FROM AUTHOR]

Deploying a certain capacity of storage assets in a renewable-only generation portfolio is unarguably imperative to maintain system reliability. These storage assets can be owned and managed by utilities, renewable energy developers, system operator, or any private merchant. Intermediary storage merchant can invest on these storage assets through capacity contracts. Investing on capacity contracts is risky owing to the inherent uncertainties in the energy market and renewable energy generation. By contracting a selected set of geographically diverse storage assets, the merchant can mitigate the risk of revenue loss and improve the return profile. This paper aims to determine the optimal storage portfolio for the merchant from a risk averse perspective. We formulate this problem as a tri-level stochastic optimization program. The upper level minimizes the aggregate risk for the intermediary merchant, the mid-level maximizes the expected profit for the owner of the non-contracted storage assets, and the lower level clears a day-ahead electricity market. The proposed tri-level problem is reformulated as a bi-level program and solved by column-and-constraint generation technique. The experiments are conducted on an IEEE 24-bus and 96-bus systems, and the generation is assumed to be wind and solar only. The impact of regional and geographical diversification on the created portfolios is studied. [ABSTRACT FROM AUTHOR]

Synchronous generators are operating for less time than before or being decommissioned in the National Electricity Market (NEM) of Australia, due to the proliferation of asynchronous wind and solar generation. Sub-networks of the NEM will face inertia shortages in the near future. This paper develops a formulation of zonal inertia constrained generator dispatch for power systems with a diversified generator portfolio including synchronous generators, synchronous condensers, inverter-interfaced generators and energy storages. Zonal inertia constraints are formulated in unit commitment and optimal power flow to limit the rate of change of frequency (RoCoF) in the event of network separation. Load frequency relief is also considered to reduce the ramp rate requirement of primary reserve. The proposed formulation can reduce the average cost of primary reserve and maintain zonal inertia adequacy to constrain RoCoF in case of the trip of the interconnector(s). [ABSTRACT FROM AUTHOR]

This paper presents an off-grid sustainable power generation system suitable for rural areas of developing countries such as India where open wells are available for the purpose of irrigation and meeting the daily requirements of local families. The proposed scheme comprises of a small wind energy system with pumped-hydro energy storage (PHES), which uses an open well as a source of water. The proposed system is different from all available wind-PHES systems in many ways. It uses two upper reservoirs instead of one; the hydraulic pump gets rotational energy directly from the wind turbine, while the pico-hydro turbine coupled with electric generator gets power from the potential energy of water stored in the upper reservoir. The mathematical model of the system has been developed and the actual wind speed data are used to carry out simulation for evaluation of the model performance. The attractive features of the scheme are its reliability, simplicity, and capability to supply continuous power at constant voltage exactly equal to the rated one in spite of wind speed variations. Another interesting use of the proposed system is to supply water to the locals along with electric power supply. [ABSTRACT FROM AUTHOR]

Environmental pollution, rapid depletion of fossil fuels, and high energy losses during transmission-distribution are the main problems of traditional power grids. This motivates the development of microgrids (MGs), which are a localized network of fossil fuel and renewable generators, energy storage systems, and electrical loads. Due to the limited operational capacity of individual MGs, multiple adjacent MGs can be networked to form a cluster of interconnected MGs. This paper develops a robust energy management and scheduling model for the cooptimization of internal network operation inside MGs and external energy sharing between MGs. The uncertainty of renewable energy sources is handled by proposing a data-driven robust optimization model with a self-adaptive uncertainty set. This set is constructed by the kernel density estimation method based on the distributional information extracted from uncertainty data. To account for the multilevel and sequential decision-making process of scheduling, the energy management model is formulated as an adjustable robust optimization problem by incorporating wait-and-see decision variables. The results show that compared to conventional robust optimization models, the proposed model is more effective in dealing with uncertainty and can ensure the robustness of scheduling decisions at a lower cost. [ABSTRACT FROM AUTHOR]

Summary: The renewable energy (e.g., solar photovoltaic)‐based grid‐connected microgrid (MG) with composite energy storage system (CESS) is feasible to ensure sustainable and quality power to the commercial and domestic load demands. Effective control systems provide the dynamic performance of such deployed MGs. This paper investigates the application of the finite control‐set model predictive controller (FCS‐MPC) for solar photovoltaic‐based grid‐connected MGs with composite energy storage. FCS‐MPC considers the discrete nature of interfacing (DC–AC and DC–DC) converters into the control algorithm to predict the optimal control command for reference current tracking. Compared to classical control approaches, FCS‐MPC provides a fast‐dynamic response, discards the modulation stage, and effectively handles the effects of dynamic source and load variations and nonlinear loads. The control system encapsulates a proportional–integral (PI) controller, low‐pass filter (LPF), power management algorithm (PMA) unit, and followed by the FCS‐MPC approach. The CESS unit consists of a battery and supercapacitor storage system. The efficacy of the FCS‐MPC approach is verified through the MATLAB/Simulink results. Solar photovoltaic variation due to irradiance, utility grid availability, electricity pricing, and dynamic load variations are considered in the implementation. Furthermore, real‐time simulation of the proposed method is validated using OPAL‐RT OP4510 real‐time simulator. [ABSTRACT FROM AUTHOR]

Climate change motivated by human activities constitutes one of the main challenges of this century. To cut carbon emissions in order to mitigate carbon's dangerous effects, the current energy generation mix should be shifted to renewable sources. The main drawback of these technologies is their intermittency, which will require energy storage systems to be fully integrated into the generation mix, allowing them to be more controllable. In recent years, great progress to develop an effective and economically feasible energy storage systems, particularly motivated by the recent rise of demand for electric transportation, has been made. Lithium-ion (Li-ion) battery prices have fallen near 90% over the past decade, making possible the affordability of electric vehicles and transforming the economics of renewable energy. In this work, a study on storage capacity demand previously presented as conference paper is expanded, including a deep analysis of the Spanish generation mix, the evaluation of the energy storage requirements for different low-carbon and carbon-free scenarios in Mainland Spain, and the calculation of the CO2 emissions' reduction and the associated storage costs. [ABSTRACT FROM AUTHOR]

The popularity of electric vehicles (EVs) is increasing day by day due to their environmentally friendly operation and high milage as compared to conventional fossil fuel vehicles. Almost all leading manufacturers are working on the development of EVs. The main problem associated with EVs is that charging many of these vehicles from the grid supply system imposes an extra burden on them, especially during peak hours, which results in high per-unit costs. As a solution, EV charging stations integrated with hybrid renewable energy resources (HREs) are being preferred, which utilize multi-energy systems to produce electricity. These charging stations can either be grid-tied or isolated. Isolated EV charging stations are operated without any interconnection to the main grid. These stations are also termed standalone or remote EV charging stations, and due to the absence of a grid supply, storage becomes compulsory for these systems. To attain maximum benefits from a storage system, it must be configured properly with the EV charging station. In this paper, different types of the latest energy storage systems (ESS) are discussed with a comprehensive review of configurations of these systems for multi-energy standalone EV charging stations. ESS in these charging stations is applied mainly in three different configurations, named single storage systems, multi-storage systems, and swappable storage systems. These configurations are discussed in detail with their pros and cons. Some important expectations from future energy storage systems are also highlighted. [ABSTRACT FROM AUTHOR]

Summary: Nowadays, microgrids are emerging as an invaluable framework for the integration of renewable energy sources and demand response programs. In such systems, energy storage facilities are also frequently deployed to properly manage surplus energy from renewable sources on pursuing more efficient management of the system. Hybrid storage systems in which various storage facilities are combined may result in a more effective solution than only considering one storage technology. This way, the good features of the different technologies may be jointly exploited while their drawbacks are minimized. Due to the large‐scale integration of renewable energies in this kind of grid, coping with uncertainties becomes a critical issue. Moreover, the operation of microgrids frequently deals with other kinds of uncertainties related to energy pricing from the upscale grid (in the case of grid‐connected mode) or local demand. This way, proper modeling of uncertainties is essential for adequately operating these systems. This paper contributes to this pool by developing a novel interval‐based formulation, for optimal scheduling of microgrids considering battery and pumped‐hydro storage systems. To achieve this goal, the optimal scheduling of a microgrid with pumped‐hydro and battery energy storage considering demand response is modeled, firstly. Then, the new interval‐based formulation is used to cope with the uncertainties. Finally, the suggested model is verified using simulations in various cases, and the results confirm the effectiveness of the novel interval‐based formulation for the optimal scheduling of microgrid with pumped‐hydro and battery energy storage under uncertainty. [ABSTRACT FROM AUTHOR]

Energy storage will become indispensable to complement the uncertainty of intermittent renewable resources and to firm the electricity supply as renewable power generation becomes the mainstream new-built energy source and fossil fuel power plants are phased out to meet carbon-neutral utility targets. Current energy storage methods based on pumped storage hydropower or batteries have many limitations. Thermal energy storage (TES) has unique advantages in scale and siting flexibility to provide grid-scale storage capacity. A particle-based TES system is projected to have promising cost and performance characteristics to meet the future growing energy storage needs. This paper introduces the system and components required for particle TES to become technically and economically competitive. The system integrates electric particle heaters, particle TES within insulated concrete silos, and an efficient air-Brayton combined-cycle power system to provide power for storage durations up to several days via low-cost, high-performance storage cycles. Design specifications and cost estimation of major components in a commercial-scale system are presented in this paper. A techno-economic analysis based on preliminary component designs and performance indicates that particle TES integrated with an air-Brayton combined-cycle power system has a path to achieve the targeted levelized cost of storage of 5 ¢/kWh-cycle at a round-trip efficiency of 50% when taking low-cost energy-specific components and leveraging basic assets from existing thermal power plants. The cost model provides insights for further development and economic potentials for long-duration energy storage. [ABSTRACT FROM AUTHOR]

Studies have shown that the role of energy storage systems in human life is increasing day by day. Therefore, this research aims to study the latest progress and technologies used to produce energy storage systems. It also discusses and compares the most recent methods used by researchers to model and optimize the size of these tools and evaluates the strengths and weaknesses of each. Investigations have shown that using energy storage systems in hybrid stand-alone power generation systems based on renewable energy increases the reliability of the power generation systems and increases their efficiency. It has also reduced the cost of transmitting the power grid to remote areas. Furthermore, this study showed that advances in energy storage technology in recent years have led to the development and promotion of clean microgrids. In addition, this review paper also addresses energy storage technology issues and proposes practical and applied solutions. [ABSTRACT FROM AUTHOR]

This paper reports on the status of technology development under a national project launched in 2019 to address the problem of decreased system inertia associated with the large-scale integration of renewable energy. The project comprises two parts: the development of a system inertia observation technology using a continuous monitoring system to observe inertia and development of an inverter equipped with a function to provide virtual inertia as a countermeasure device. Utilizing both these efforts, the project aims to facilitate the introduction of renewable energy in the future with minimum restrictions. It was confirmed that the trend of inertia observed with the developed method was generally the same as that of the total inertia of synchronous machines observed by an electric utility. The effectiveness of the countermeasure device in reducing the frequency swing during a disturbance was confirmed through evaluation tests. [ABSTRACT FROM AUTHOR]

The move towards a greener energy mix to fight climate change propels investments in converter-interfaced resources such as wind and photovoltaics, energy storage systems and electric vehicles. The ongoing evolution of the power system is occurring at a very fast pace, challenging transmission and distribution system operators to seek solutions that are not only adequate for this moment but also for future scenarios. Ongoing research in the fields of power electronics, power systems and control aims at developing control strategies that will help the energy transition to occur, while keeping a stable, secure and reliable power system. The objective of this paper is to present a critical review of the control strategies developed for grid-connected power converters found in renewable energy systems, energy storage systems and electric vehicles. The impact of grid-connected converters on the stability of power grids is also reviewed, highlighting the promising control strategies for enhancing system stability. [ABSTRACT FROM AUTHOR]

Because generating electricity significantly contributes to global greenhouse gas emissions, meeting the 2015 Paris Agreement and 2021 Glasgow Climate Pact requires rapidly transitioning to zero or low-emissions electricity grids. Though the installation of renewables-based generators—predominantly wind and solar-based systems—is accelerating worldwide, electrical energy storage systems, such as pumped storage hydropower, are needed to balance their weather-dependent output. The authors of this paper are the first to examine the status and potential for pumped storage hydropower development in 24 Pacific Rim economies (the 21 member economies of the Asia Pacific Economic Cooperation plus Cambodia, Lao PDR, and Myanmar). We show that there is 195 times the pumped storage hydropower potential in the 24 target economies as would be required to support 100% renewables-based electricity grids. Further to the electrical energy storage potential, we show that pumped storage hydropower is a low-cost, low-greenhouse-gas-emitting electrical energy storage technology that can be sited and designed to have minimal negative (or in some cases positive) social impacts (e.g., requirements for re-settlement as well as impacts on farming and livelihood practices) and environmental impacts (e.g., impacts on water quality and biodiversity). Because of the high potential for pumped storage hydropower-based electrical energy storage, only sites with low negative (or positive) social and environmental impacts such as brownfield sites and closed-loop PSH developments (where water is moved back and forth between two reservoirs, thus minimally disturbing natural hydrology) need be developed to support the transition to zero or low-carbon electricity grids. In this way, the advantages of well-designed and -sited pumped storage hydropower can effectively address ongoing conflict around the social and environmental impacts of conventional hydropower developments. Noting the International Hydropower Association advocacy for pumped storage hydropower, we make recommendations for how pumped storage hydropower can sustainably reduce electricity-sector greenhouse gas emissions, including through market reforms to encourage investment and the application of standards to avoid and mitigate environmental and social impacts. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a novel control scheme on AC/DC ring bus islanded microgrid under unbalanced and non‐linear loads. The DC bus is integrated with the fuel cell, one wind turbine, and two batteries. The DC bus can be divided into two sub‐sections, where the first zone is supported by the fuel cell and battery 1, and the second zone is installed with the wind turbine and battery 2. The AC bus is also able to be sectionalized into two sub‐sections where the diesel generator and the unbalanced load are located on the first section and the non‐linear load with one wind turbine are placed on the other section. The DC bus is connected to the AC bus through two parallel three‐phase lines each one configured by three single‐phase inverters. The proposed control scheme in the ringed and separated modes presents several contributions including balancing the unbalanced loads, compensating the harmonics of non‐linear loads, improving the voltage stability and sag/swells, enabling partial operation under outages, and enhancing resilience. In the ring mode, wind turbine 1 and diesel generator inject balanced and linear P‐Q powers to the system as 39 kW/6 kVAr and 7 kW/9 kVAr, respectively. In the separated mode, the P‐Q powers of wind turbine 1 are 36 kW/9 kVAr and they are 15 kW/9 kVAr for diesel generators. In both modes, the unbalanced and non‐linear powers are supplied by the DC bus. The results verify that the developed control strategy efficiently deals with harmonic components, unbalanced currents and voltage issues. [ABSTRACT FROM AUTHOR]

With the aggregation of renewable energy in the power system, the uncertainty caused by the renewable energy affects the planning and operation of power systems. Meanwhile, the existing planning models fail to consider renewable energy uncertainty methods, specifically concerning renewable energy confidence and future possible scenarios; thus, a confidence-based scenario cluster method is presented. A novel generator, network, load, and energy storage (GNLS) co-planning model is proposed in the paper. First, a confidence-based scenario cluster is built, which can reflect uncertainties by clustering and analyzing wind, solar, and load. Second, the proposed model focuses on load and energy storage co-planning, and in addition, relevant flexible indices are used to assess the model. Finally, the GNLS co-planning model is built as a bi-level stochastic model on continuous time scales. The model is solved using the Benders decomposition algorithm. The method in this paper is validated using an IEEE RTS 24-bus and a real test system in China to demonstrate the reduction in renewable energy curtailment and optimization of economic factors in power system planning.

The vanadium redox flow battery (VRB) is well-suited for applications with renewable energy devices. This paper presents a practical analysis of the VRB for use in a microgrid system. The first part of the paper develops a reduced order circuit model of the VRB and analyzes its experimental performance efficiency during deployment. The model parameters of the various VRB system components were estimated from experimental field data. The parasitic losses of the circulation pumps power consumption were predicted during different operating situations. The second part of the paper addresses the implementation issues of the VRB application in a photovoltaic-based microgrid system. Commercially available chargers designed for lead-acid battery systems were shown to be non-optimal for VRB systems and a new dc–dc converter control was proposed to provide improved charging performance. The system model was validated with field-obtained experimental data. [ABSTRACT FROM PUBLISHER]

This paper highlights the key results from the Renewable Electricity (RE) Futures Study. It is a detailed consideration of renewable electricity in the United States. The paper focuses on technical issues related to the operability of the U.S. electricity grid and provides initial answers to important questions about the integration of high penetrations of renewable electricity technologies from a national perspective. The results indicate that the future U.S. electricity system that is largely powered by renewable sources is possible and the further work is warranted to investigate this clean generation pathway. The central conclusion of the analysis is that renewable electricity generation from technologies that are commercially available today, in combination with a more flexible electric system, is more than adequate to supply 80% of the total U.S. electricity generation in 2050 while meeting electricity demand on an hourly basis in every region of the United States. [ABSTRACT FROM PUBLISHER]

Due to the increasingly serious energy crisis and environmental pollution problem, traditional fossil energy is gradually being replaced by renewable energy in recent years. However, the introduction of renewable energy into power systems will lead to large voltage fluctuations and high capital costs. To solve these problems, an energy storage system (ESS) is employed into a power system to reduce total costs and greenhouse gas emissions. Hence, this paper proposes a two-stage method based on a back-propagation neural network (BPNN) and hybrid multi-objective particle swarm optimization (HMOPSO) to determine the optimal placements and sizes of ESSs in a transmission system. Owing to the uncertainties of renewable energy, a BPNN is utilized to forecast the outputs of the wind power and load demand based on historic data in the city of Madison, USA. Furthermore, power-voltage (P-V) sensitivity analysis is conducted in this paper to improve the converge speed of the proposed algorithm, and continuous wind distribution is discretized by a three-point estimation method. The Institute of Electrical and Electronic Engineers (IEEE) 30-bus system is adopted to perform case studies. The simulation results of each case clearly demonstrate the necessity for optimal storage allocation and the efficiency of the proposed method. [ABSTRACT FROM AUTHOR]

To solve the problem of safe and stable grid operation caused by the uncontrollability of renewable energy power generation with a high proportion, this paper focuses on the method of energy storage participation in grid supply and demand balance regulation based on differentiated electricity prices. From the perspective of demand-side and regulable resources, the paper investigates the method of using differentiated electricity prices to improve demand-side responsiveness and expand energy storage operation revenue, so as to explore and activate the potential of regulable resources in the grid. Firstly, the necessity and feasibility of considering differentiated electricity prices are analyzed. Secondly, a demand-side response and energy storage regulation model based on differentiated electricity prices is established, and the supply–demand balance regulation method considering differentiated electricity prices is proposed. Then, the supply–demand balance regulation process under two conditions before and after the implementation of differentiated electricity prices is compared and analyzed through case simulation. Finally, via the practical example, the effectiveness of the method is verified, and the proposed method is able to reduce the demand for energy storage by half in rated power and reduce the rated capacity of the energy storage to 8.66%.

Green ammonia, a promising zero-carbon energy storage vector, has never been produced using solely tidal stream energy despite its predictable characteristics. Combining tidal stream sites with a phase difference (tidal phasing) facilitates anticorrelation between these sites' power profiles, enabling a more consistent power output. Green ammonia production benefits from a steady and predictable power input. The objective of this paper is to determine if nearby tidal sites have a large enough phase difference (anticorrelation) to reduce the cost of ammonia production. Moreover, producing green ammonia from underutilized or unutilized remote and grid-constrained tidal stream sites may enable viability of these sites. This paper is the first analysis of green ammonia production using solely tidal stream energy and the first analysis of tidal phasing for green fuel production. Two UK case studies are presented in i) the North Channel of the Irish Sea and ii) Orkney. There are tidal sites in each which have a phase difference (e.g. the Mull of Kintyre/Sound of Islay, and Graemsay/North Ronaldsay with correlation coefficients of 0.17 and −0.02 respectively), utilising this phase difference reduces the levelized cost of ammonia by 8% in the Irish Sea and by 12% in Orkney. [ABSTRACT FROM AUTHOR]

The open-source industry has its independent track record as a part of software science. It has presence in most of industrial sectors. Here is a particular study of the application of open-source solutions in the energy sector as well as the renewables. The recent development of smart grids took enhancement by the open-source solutions. There are needs for dynamic-analysis on the economic effects of implementation of open-source software solutions in the management of the smart grids. In this paper, a new perspective, "implementation of open source in the energy management", is proposed, which defines the levels of conversion. In order to demonstrate the effectiveness of this methodological approach, capabilities of exporting hightechnology software solutions were examined, and then previously developed indices of sustainable energy and of economic development of the world were analysed. As a result, the methodological approach for shaping and defining the sustainability zone was determined upon the dynamicanalysis on the development of socio-economic system. [ABSTRACT FROM AUTHOR]

The intermittency and stochasticity nature of distributed renewable energy sources has introduced great challenges to the efficiency and security of energy distribution system operations. To address the negative impacts of intermittent renewable energy sources, this paper proposes a day-ahead optimal operation strategy utilizing distributed energy resources based on the framework of the interconnected multi-energy system. First, a framework and mathematical models of multi-energy residential systems (MERS) are proposed. Based on the characteristics of residential energy distribution networks, the complex MERS models are reformulated to relieve the computational burden. Furthermore, the uncertainty factors such as renewable energy generation fluctuations and demand variations are handled by a reformulated chance constrained programing technique. The feasibility and effectiveness of the proposed method are validated through a combined electric power and natural gas test system. Compared to similar models and methods in the existing literature, the proposed method performs better in terms of solution time, model scalability, and robustness in handling uncertainties. [ABSTRACT FROM AUTHOR]

A renewable-based system able to meet pure electric, space heating and cooling loads of a small office building located in Southern Italy is evaluated here. The proposed energy conversion system is based on a photovoltaic plant, an electric-driven heat pump and electrical energy storage. Energy and environmental performance of this system has been evaluated by means of a dynamic simulation software changing photovoltaic nominal power (4.5-7.5 kW), battery capacity (3.2-9.6 kWh), and reference electrical system. The aim of the paper is the energy and environmental comparison on monthly, as well as, on yearly basis between the proposed system and the reference conventional system. The conventional system is based on the power grid, a natural gas fired boiler and an electric-driven chiller. The analysis here reported shows how monthly variation of electric reference system, due to different monthly Italian electricity mix production, influences the energy and environmental performance of the solar-based system. The proposed system guarantees high primary energy saving and equivalent carbon dioxide emissions reduction up to about 93%. [ABSTRACT FROM AUTHOR]

The global move toward efficient energy consumption and production has led to remarkable advancements in the design of the smart grid infrastructure. Local energy trading is one way forward. It typically refers to the transfer of energy from an entity of the smart grid surplus energy to one with a deficit. In this paper, we present a detailed review of the recent advances in the application of game-theoretic methods to local energy trading scenarios. An extensive description of a complete game theory-based energy trading framework is presented. It includes a taxonomy of the methods and an introduction to the smart grid architecture with a focus on renewable energy generation and energy storage. Finally, we present a critical evaluation of the current shortcomings and identify areas for future research. [ABSTRACT FROM AUTHOR]

Increasing energy demand worldwide is directly related to the power generation process. Carbon emissions cum greenhouse gas emissions have direct contact with global warming and climate change. Energy generation from conventional power plants is the cause of a huge amount of environmental pollution. Different renewable energy sources are a great option to fulfil all the criteria as these are cost-effective, environment-friendly and abundantly found in nature. But renewable energy sources are varied in nature and for overcoming this problem; renewable energy-based hybrid system is a better solution. This paper reviews various challenges and recent developments in the area of the hybrid renewable energy system and also reviewing a backup system like pumped hydro energy storage system (PHES). We also discuss some real-world case studies of renewable energy-based hybrid power plants adopted in various parts of the world. This paper concludes with suggestions for future research opportunities in this field. [ABSTRACT FROM AUTHOR]

In this paper, a novel liquefied air energy storage (LAES) system driven by wind energy and natural gas, integrated with a two‐stage supercritical carbon dioxide cycle is proposed and investigated. Three different sensible thermal energy storage (TES) systems are considered in this study to store the heat produced in the compressions stage and use it later to improve the performance. The proposed system is analyzed in terms of energy, exergy, exergo‐economic, and environmental impacts. A detailed economical and technical investigation is carried out to determine system hotspots, exergy destruction rates, and the performance of the system and subsystems. Finally, by considering ten design variables, the nondominated sorting genetic algorithm‐II (NSGA‐II) is employed to evaluate the optimal design solutions for double objective functions, including cost per unit of exergy and overall system exergy efficiency. Results indicate that for a 50 MW of discharging power, 80.75 MW of charging electricity and 1.22 kg/s of fuel are required. Additionally, the product cost per unit of exergy and the levelized costs are calculated as 32.02 $/GJ and 0.133 $/kWh, respectively. The results of the optimization study also show that for the optimal Pareto solution, the energy efficiency would be 52.2% while the exergy efficiency is 45.26%. [ABSTRACT FROM AUTHOR]

Recently, implementation of Battery Energy Storage (BES) with photovoltaic (PV) array in distribution networks is becoming very popular in overall theworld. Integrating PV alone in distribution networks generates variable output power during 24-hours as it depends on variable natural source. PV can be able to generate constant output power during 24-hours by installing BES with it. Therefore, this paper presents a new application of a recent metaheuristic algorithm, called SlimeMould Algorithm (SMA), to determine the best size, and location of photovoltaic alone or with battery energy storage in the radial distribution system (RDS). This algorithm is modeled from the behavior of SMA in nature. During the optimization process, the total active power loss during 24-hours is used as an objective function considering the equality and inequality constraints. In addition, the presented function is based on the probabilistic for PV output and different types of system load. The candidate buses for integrating PV and BES in the distribution network are determined by the real power loss sensitivity factor (PLSF). IEEE 69-bus RDS with different types of loads is used as a test system. The effectiveness of SMA is validated by comparing its results with those obtained by other well-known optimization algorithms. [ABSTRACT FROM AUTHOR]

Recent years have seen a surge in interest in DC microgrids as DC loads and DC sources like solar photovoltaic systems, fuel cells, batteries, and other options have become more mainstream. As more distributed energy resources (DERs) are integrated into an existing smart grid, DC networks have come to the forefront of the industry. DC systems completely sidestep the need for synchronization, reactive power control, and frequency control. DC systems are more dependable and productive than ever before because AC systems are prone to all of these issues. There is a lot of unrealized potential in DC power, but it also faces some significant challenges. Protecting a DC system is difficult because there is no discrete location of where the current disappears. DC microgrid stability that is dependent on inertia must also be considered during the planning stage. The problems that DC microgrids have include insufficient power quality and poor communication. The power quality, inertia, communication, and economic operations of these value streams, as well as their underlying architectures and protection schemes, are all extensively discussed in this paper. This review paper examines the pros and cons of both grid-connected and isolated DC microgrids. In addition, the paper compares the different kinds of microgrids in terms of power distribution and energy management agency, such as the prerequisites for a DC microgrid’s planning, operation, and control that must be met before state-of-the-art systems can be implemented.

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]

A developing country that does not have adequate energy solutions in non-interconnected zones (ZNIs) undoubtedly experiences adverse effects in terms of its competitiveness, as well as economic and social development. The primary sources of electrical energy in these communities are diesel generators, which are expensive and not environment-friendly. This paper seeks to describe how to reduce the consumption of this fossil fuel in ZNIs. The technical and economical implementation of a small-scale photovoltaic system with and without a hybrid energy storage system connected to the grid is studied, based on the incentive policy of the Colombian regulation. A mixed-integer nonlinear programming optimization model was developed, which includes the storage costs of a lead-acid battery and supercapacitor, to analyze the benefits of the electricity tariff and to maximize the revenues of the photovoltaic generation system. The conclusions of this study offer policy suggestions and economic incentives to enhance the use of renewable energy sources in the ZNIs of Colombia. [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]