Electrical Storage Systems Research Articles

A robust optimization framework for energy hub operation considering different time resolutions: A real case study

In this paper, a robust optimization framework is proposed for solving the energy hub operation problem in the presence of renewable energy resources (RERs) and three electrical, cooling and thermal storage systems. The study hub is a real case study in a hospital building in Hamedan, Iran. All the input parameters are obtained from real data by connecting a dw-6095 Lutron power analyzer to the hub equipment. Furthermore, the study problem is modeled as a mixed-integer non-linear programming (MINLP) problem and is solved in the form of 8 different case studies using the DICOPT solver in GAMS software. Our analysis of the simulation results reveals that considering the uncertainties led to a 6.41% increase in the total operation costs. The results also indicate that storage systems increased flexibility and reduced the operation costs by 0.87%. Moreover, the problem was solved with three different time resolutions, and the results mirrored an increase in the accuracy and solution time due to the increase in the resolution. Finally, the hub performance is assessed under three contingency events, and the results show that the exclusion of the boiler leads to about 5563.3 kWh of energy not served (ENS).

Analytic optimization of Joule–Brayton cycle-based pumped thermal electricity storage system

Having the advantages of high efficiency and high energy storage density, pumped thermal electricity storage (PTES) is a promising mechanical energy storage technology that is typically suitable for large-scale energy storage. To obtain the combined influence of various factors and losses on the performance of a PTES system, an analytic optimization study for the individual process of charge, storage, and discharge are conducted in this study. The results indicate that the maximum working temperature and the efficiency of the turbomachines are positively correlated to the round-trip efficiency and the energy storage density. Moreover, the optimal pressure ratio needs to be determined to maintain the balance between the efficiency and the energy storage density. The Joule–Brayton PTES system can achieve maximum round-trip efficiencies of 81.2%, 85.6%, and 88.2% at 900 K, 1100 K, and 1300 K, respectively, under a turbomachine efficiency of 0.9. With reasonable temperature and pressure losses (not optimal components), a round-trip efficiency of 59% and an energy storage density of 60 kWh/m3 can be obtained at the maximum temperature of 1100 K. The above analysis and optimization based on the exergy method provide a theoretical approach for the future design of a Joule–Brayton cycle-based PTES system.

A hybrid robust-stochastic approach for unit commitment scheduling in integrated thermal electrical systems considering high penetration of solar power

With increasing environmental concerns, limited oil reserves and governmental incentives, installation of photovoltaic (PV) systems have gained substantial momentum in smart electric distribution systems (EDS), which is considered to be a great success. That said, widespread integration of these PV units, comes with uncertainty issues that puts the flexibility of the system at stake. In this regard, local district heating systems (DHS) are considered to be an effective tool in enhancing the flexibility of the power system on account of their high thermal inertia. In this study, we propose hybrid robust (RO)- stochastic programming (SP) optimization framework for commitment scheduling of distributed generation units and local DHS considering high penetration of PV units. Furthermore, the impact of flexible thermal and electrical loads on total operational cost and overall flexibility of the system is evaluated. The SP is utilized to deal obscurity of solar radiation, and RO is utilized to handle price uncertainties. The uncertainty management via the electrical storage system is also scrutinized. The results are evaluated by different cases studies implemented on an integrated IEEE 33-bus EDS and an 8-node DHS. Eventually, the mixed integer linear problem is solved with a standard CPLEX solver.

Adaptive Protection Coordination Method Design of Remote Microgrid for Three-Phase Short Circuit Fault

Generally, the fault current supplied by inverter-based renewable energy sources (IBRES) and electrical storage systems (ESS) is about 1.2 to 2 times their rated current and much lower than synchronous generators because the former acts as a current source and the latter acts as a voltage source. A conventional power system in a small island is composed of only synchronous generators and protected from short circuit faults using an overcurrent relay (OCR). However, in the remote microgrid with IBRES, ESS, and synchronous generators, the fault current varies depending on the configuration of generation sources. Namely, the fixed OCR protection method cannot protect microgrids from short circuit faults. This paper proposes an adaptive protection method to protect the microgrid from faults by actively changing the OCR setting according to the state of the generator source combination. A microgrid with ESS and a synchronous generator is modeled and simulated through PSCAD/EMTDC software to validate the proposed adaptive protection method.

Integrated life-cycle optimisation and supply-side management for building retrofitting

Building retrofitting is a powerful approach to enhance building energy performance. The net-zero ambition urges the need to renovate building energy system in view of the life-cycle optimal, to address climate and environmental challenges. Existing retrofitting and optimisation solutions are generally based upon minimising operational energy or cost. However, although building retrofitting can reduce the energy use at the operating phase, additional materials would result in increased embodied energy. The objective of this paper is to devise a novel building retrofitting approach through the integration of life-cycle optimisation and supply-side management. It is an interactive two-set optimisation approach aimed at minimising overall life-cycle energy consumption through determining the optimal design configuration and operating plan of retrofitting energy devices. The essential retrofitting energy devices include passive retrofitting options (i.e., photovoltaic panel and solar thermal collector) and active retrofitting options (i.e., biomass boiler, ground source heat pump, heat storage, electricity storage, and cogeneration system). A modern 3-floor office building in Manchester, the United Kingdom, is adopted to assess the performance of the proposed refurbishment approach. The real-world situation is represented by historical electricity and gas consumption profiles, current building design information, historical weather profile, as well as life-cycle inventory information. The proposed retrofitting optimisation approach can help decision-makers select the optimal retrofitting solution so as to reduce the overall life-cycle energy consumption of office buildings.

SET-UP OF A NEW COORDINATED PROCESS FOR ANCILLARY SERVICES PROVISION FROM DSO TO THE TSO: AN INNOVATIVE APPROACH TO THE EXPLOITATION OF FLEXIBILITIES CONNECTED TO THE DISTRIBUTION GRID

The paper describes in detail the network and the resources considered in the Italian Demonstrator implemented within the EU-SysFlex project, in which advanced Smart Grid devices are integrated with SCADAs (Supervisory Control And Data Acquisition) and optimization platforms. The final scope consists of providing flexibilities from local resources to the TSO (Transmission System Operator) on the ancillary services market, considering both TSO and DSO (Distribution System Operator) needs and constraints. The main functionality is the calculation of the aggregated reactive power capability to be provided at the TSO/DSO interface (High to Medium Voltage - HV/MV - substation), based on current network conditions. The demonstrator makes use of some photovoltaic generators, one BESS (Battery Electric Storage System), two OLTCs (On Load Tap Changers) and two STATCOMs (Static Synchronous Compensators).

Development of Cation-Disordered Rocksalt Cathodes

In order to meet the demand for large-scale energy storage applications such as electric vehicles and power grid storage systems, Li-ion batteries (LIBs) with higher energy density and power density, lower cost, better safety, and longer lifespans are needed. In the past several years, cation-disordered Li-excess rocksalts (DRXs) have quickly emerged as a new class of promising high-energy LIB cathode materials. [1] This is largely owing to their high charge storage capacities, a result of combined redox reactions of cationic transition metals and anionic oxygen similar to what was reported on the Li- and Mn-rich NMC cathodes. Compared to the conventional layered oxides, the three-dimensional host structure is considerably more stable as the randomized cation distribution eliminates structural instability associated with changes in the interlayer spacing. However, DRX cathodes currently face challenges in cycling stability as extensive involvement of oxygen redox, which is needed for the capacity boost, often leads to fast capacity fade and, in some cases, voltage hysteresis.In this presentation, we will show our recent effort in understanding charge storage mechanisms, materials degradation mechanisms, and key factors influencing DRX cathode performance. [2-6] Our perspectives on future development will also be discussed. References Lee, J.; Urban, A.; Li, X.; Su, D.; Hautier, G.; Ceder, G. Unlocking the Potential of Cation-Disordered Oxides for Rechargeable Lithium Batteries.Science 2014, 343, 519.Kan, W. H.; Chen, D.; Papp, J. K.; Shukla, A. K.; Huq, A.; Brown, C. M.; McCloskey, B. D.; Chen, G. Unravelling Solid-State Redox Chemistry in Li3Nb0.3Mn0.4O2 Single-Crystal Cathode Material. Chem. Mater. 2018, 30, 1655.Kan, W. H.; Wei, C.; Chen, D.; Bo, T.; Wang, B. T.; Zhang, Y.; Tian, Y.; Lee, J. S.; Liu, Y.; Chen, G. Evolution of Local Structural Ordering and Chemical Distribution upon Delithiation of a Rock Salt–Structured Li3Ta0.3Mn0.4O2 Cathode. Adv. Funct. Mater. 2019, 29, 1808294.Chen, D.; Kan, W. H.; Chen, G. Understanding Performance Degradation in Cation-Disordered Rock-Salt Oxide Cathodes. Energy Mater. 2019, 9, 1901255.Chen, D.; Wu, J.; Papp, J. K.; McCloskey, B. D.; Yang, W.; Chen, G. Role of Redox-Inactive Transition-Metals in the Behavior of Cation-Disordered Rocksalt Cathodes. Small 2020, 16, 2000656.Ahn, J.; Chen, D.; Chen, G.. A Fluorination Method for Improving Cation-Disordered Rocksalt Cathode Performance. Energy Mater. 2020, 10, 2001671.

Preliminary Design of a Self-Sufficient Electrical Storage System Based on Electrolytic Hydrogen for Power Supply in a Residential Application

The use of renewable energy and hydrogen technology is a sustainable solution for the intermittent feature of renewable energies. Hence, the aim of the present work is to design a self-sufficient system for a one-family house by coupling a solar photovoltaic array and an anion exchange membrane water electrolyzer (AEMWE). The first step is the selection of the photovoltaic panel by using PV-SYST 7.0 software. Then, the hydrogen production system is calculated by coupling the electrolyzer and photovoltaic panel current–potential curves. A fuel cell is selected to use the hydrogen produced when solar energy is not available. Finally, the hydrogen storage tank is also estimated to store hydrogen for a design basis of four consecutive cloudy days according to the hydrogen consumption of the fuel cell. The whole system is designed by a simple procedure for a specific location in Ciudad Real (Spain) for January, which is known as the coldest month of the year. The simple procedure described in this work could be used elsewhere and demonstrated that the hydrogen production at low scale is a suitable technology to use renewable energy for self-energy supporting in a residential application without any connection to the grid.

Multicriteria optimization of Brayton-like pumped thermal electricity storage with liquid media

A multi-objective and multi-parametric optimization of a Pumped Thermal Electricity Storage system based on Brayton cycles is presented by the calculation of different Pareto fronts and the associated Pareto optimal sets for energetic and design analysis, respectively. A large range of internal and external irreversibilities and the thermodynamic properties of the storage media are taken into account. The analysis shows that the heat capacity of the working fluid and the heat capacity of the storage media should be the same in the contact with the hot reservoirs and in the contact with the cold reservoir in the heat pump, but in the contact with the cold reservoir for the heat engine the ratio should be 0.33, this offers information regarding the mass flow increasing significantly the achievable values for the round-trip efficiency, power output and the heat engine efficiency in the discharge process. Optimal values are given in terms of the degree of irreversibilities in the system and a comparison is made with extreme cases of infinite and minimum sizes for the storage system. Round-trip efficiencies in the so-called optimum scale/mass-flow-ratio design point exhibits noticeably larger values compared to previously reported results including the so-called endoreversible limit, where no internal irreversibilities are considered and where the improvement can achieve 49% over the endoreversible case in the most ideal scenario. Explicit numerical values of the maximum round trip efficiency, power output, and efficiency are given for a broad range of both internal and external irreversibilities.

Progress in Development of Nanostructured Manganese Oxide as Catalyst for Oxygen Reduction and Evolution Reaction

The rise in energy consumption is largely driven by the growth of population. The supply of energy to meet that demand can be fulfilled by slowly introducing energy from renewable resources. The fluctuating nature of the renewable energy production (i.e., affected by weather such as wind, sun light, etc.), necessitates the increasing demand in developing electricity storage systems. Reliable energy storage system will also play immense roles to support activities related to the internet of things. In the past decades, metal-air batteries have attracted great attention and interest for their high theoretical capacity, environmental friendliness, and their low cost. However, one of the main challenges faced in metal-air batteries is the slow rate of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) that affects the charging and the discharging performance. Various types of nanostructure manganese oxide with high specific surface area and excellent catalytic properties have been synthesized and studied. This review provides a discussion of the recent developments of the nanostructure manganese oxide and their performance in oxygen reduction and oxygen evolution reactions in alkaline media. It includes the experimental work in the nanostructure of manganese oxide, but also the fundamental understanding of ORR and OER. A brief discussion on electrocatalyst kinetics including the measurement and criteria for the ORR and the OER is also included. Finally, recently reported nanostructure manganese oxide catalysts are also discussed.

ZeoPTES: Zeotropic Pumped Thermal Energy Storage with an Ammonia–Water Mixture as Working Fluid

The rapid rise of renewable energy production necessitates the development of large‐scale electricity storage systems. Pumped thermal energy storage (PTES), where electricity is stored in hot and cold storage units, has recently garnered a lot of interest. Previously proposed PTES systems rely on pure fluids as working fluids in Brayton‐ or Rankine‐based power cycles. Herein, ZeoPTES, a PTES system using a zeotropic mixture of ammonia and water as working fluid, is introduced. The mixture exhibits nonisothermal evaporation and condensation, which allows utilization of industrially available sensible storage units, like water or molten salt, to store the thermal energy from these phase changes. A simulation using the REFPROP 10.0 database is written to analyze the cycle. Eight parameters are identified as having an effect on system round‐trip efficiency and 30 000 simulations with random values for these parameters are run to identify the impact of all. Although efficient compressors and expanders are necessary to reach a high power‐to‐power round‐trip efficiency, the largest system‐wide losses arise from entropy generation and thermal stream mismatch in the cold and hot side heat exchangers. Using state‐of‐the‐art microchannel heat exchangers with extremely low pinch points allows for round‐trip efficiencies in excess of 70%.

DC-DC Buck Converter Circuit Simulation on Solar Panel Electricity Storage System

Electrical energy is one of the energies that humans widely use. One of the components used to generate electrical energy is solar cells. By using solar cells, energy can be stored in a battery or used directly. In stores electrical energy into the battery using DC-DC converter is still found to have a loss of power that affects the low efficiency of electricity generated. So it needs a system that can control the process of storing energy to the battery, one of which uses a DC-DC converter with Buck topology that will be used on solar panel electrical power storage system. To optimize the DC-DC Buck converter circuit, we plan a circuit simulation by considering the value of the quality factor Q of the Butterworth filter. The test results showed that the filter with a value of Q = 0.707 was of good quality with a gain of -3.1 dB. If the Q value increase, the gain will be increased, and the time it takes until the voltage stabilizes increases.

A type-2 fuzzy control for active/reactive power control and energy storage management

This paper presents a new type-2 fuzzy logic control (T2FLC) for active/reactive power (AP/RP) regulation and energy storage management of an independent microgrid (MG). The case-study MG includes sporadic renewable sources that lead to significant frequency and voltage fluctuations in the network. The rules of suggested T2FLCs are tuned such that a fractional-order sliding condition can be satisfied. Also a new approach using square-root-cubature Kalman filter is designed to optimize the membership parameters of T2FLCs. Beside AP/RP power regulation, an electrical storage system (battery energy storage system (BESS)) is managed to produce the rated power, rather than a conventional generator. It makes the device frequency separate from the synchronous generator’s mechanical inertia. Nevertheless, a BESS has a power limit – it uses a synchronous generator to sustain the BESS charge state at a certain value. Sustainable energies achieve a voltage-damping impact by supplementing an AP/RP droop strategy procedure that considerably reduces voltage oscillation created by variation of its own output power. In various disturbed scenarios the good performance of the suggested controller and energy management system is shown.

Controlling distributed energy resources via deep reinforcement learning for load flexibility and energy efficiency

Behind-the-meter distributed energy resources (DERs), including building solar photovoltaic (PV) technology and electric battery storage, are increasingly being considered as solutions to support carbon reduction goals and increase grid reliability and resiliency. However, dynamic control of these resources in concert with traditional building loads, to effect efficiency and demand flexibility, is not yet commonplace in commercial control products. Traditional rule-based control algorithms do not offer integrated closed-loop control to optimize across systems, and most often, PV and battery systems are operated for energy arbitrage and demand charge management, and not for the provision of grid services. More advanced control approaches, such as MPC control have not been widely adopted in industry because they require significant expertise to develop and deploy. Recent advances in deep reinforcement learning (DRL) offer a promising option to optimize the operation of DER systems and building loads with reduced setup effort. However, there are limited studies that evaluate the efficacy of these methods to control multiple building subsystems simultaneously. Additionally, most of the research has been conducted in simulated environments as opposed to real buildings. This paper proposes a DRL approach that uses a deep deterministic policy gradient algorithm for integrated control of HVAC and electric battery storage systems in the presence of on-site PV generation. The DRL algorithm, trained on synthetic data, was deployed in a physical test building and evaluated against a baseline that uses the current best-in-class rule-based control strategies. Performance in delivering energy efficiency, load shift, and load shed was tested using price-based signals. The results showed that the DRL-based controller can produce cost savings of up to 39.6% as compared to the baseline controller, while maintaining similar thermal comfort in the building. The project team has also integrated the simulation components developed during this work as an OpenAIGym environment and made it publicly available so that prospective DRL researchers can leverage this environment to evaluate alternate DRL algorithms.

Technical and economic analysis of Brayton-cycle-based pumped thermal electricity storage systems with direct and indirect thermal energy storage

Pumped thermal electricity storage (PTES) systems have attracted increasing attention, owing to high energy density, low cost, flexible adjustable energy storage duration, and lack of geographical restrictions. At present, theoretical research for PTES is relatively deep. Further reduction of investment costs is of great value to its development and application. This paper proposes a 10-MW PTES system with indirect thermal energy storage (TES) (I-PTES). The I-PTES and a PTES system with direct TES (D-PTES) are analyzed and compared in terms of their technical and economic performances. The results show that the I-PTES is advantageous owing to its low installation cost when its electricity storage duration exceeds 6 h, despite bearing some loss in round-trip efficiency. For longer-duration electricity storage, the energy capital cost of I-PTES can be lower than 200 $/kWh, i.e., 40% lower than that of D-PTES, whereas the penalty for its round-trip efficiency can be less than 5% after optimization. For a 10-MW I-PTES system, the optimum round-trip efficiency and energy density can reach approximately 65% and 26 kWh/m3, respectively. This research provides a more economical choice for the long-duration electricity storage, and a theoretical basis for the design and optimization of high-efficiency and low-capital-cost PTES systems.

Towards an integrated design of renewable electricity generation and storage systems for NZEB use: A parametric analysis

Although nearly zero energy buildings have attracted growing research attention, literature analysis shows that only a limited number of researches try to couple load match/grid interaction issues and environmental impacts in early design stages. The study proposes a novel multidisciplinary design approach that allows to integrate these two conflicting aspects aiming to find trade-offs. The proposed approach has been applied to a building case study, equipped with a photovoltaics system without energy storage. The results show that even though on yearly basis the energy use (5,290 kWhe) is largely overcome by the on-site energy generation (8069 kWhe), an oversized PV system alone may not be the best solution for reducing the environmental impact of the building sector, besides not being very efficient in improving load match. Afterwards, a parametric analysis was carry out analysing three redesign scenarios, obtained varying the sizes of the PV system and installing different sizes of the storage systems. The results show that the use of storage systems, in addition to decrease the grid dependency, can increase the environmental benefits arising from the renewable energy sources (e.g. there is a decrease of global warming potential of 48%, compared to the base case, with 5.28 kWp PV system and 10 kWh storage system). Conflicting results are found according to specific impact categories and this suggests the need for a holistic approach, including different domains and indicators. In this context, the proposed approach can contribute to the transition toward low-carbon energy technologies, by supporting researches and designers to take environmentally sound considerations.

Hybrid Renewable Energy System for A Sustainable House-Power-Supply

The main objective of the present research is to design a hybrid wind and solar energy-supply system for a rural residential building to meet its energy demands. The monthly averaged daily energy consumption for the dwelling was found to vary between 19 and 36 kWh. The system under consideration included some subsystems, namely: the hot-water service, the space-heating facility, and the power-utility system (wind electricity supply and storage system). The optimum design was obtained by carrying out a cost-benefit analysis for each of the subsystems. The hot-water system was designed to be based on solar flat-plate collectors, and a wind tree. The optimum hot-water facility is consisted of three flat-plate collectors, a storage heat exchanger with three coils, which are attached to flat-plate solar collectors, under-floor heating systems, and a wind tree power system. The large dimensions of the house were the limiting factor when investigating the feasibility of a solar-powered space-heating system. The existence of large windows made the space heating a very dif?cult and expensive task. The results show that the cost of the system is very expensive compared to the connection to the main grid. But on the other side, there will be a return investment value each year and the system will get all its costs after 14 years. Thus, if the average life of the system is 20 years old, the system will get profit after 14 years for six more years, in addition to the clean energy out from the system and the very beneficial positive effect on the environment.

Performance of pumped thermal electricity storage system based on reverse/forward Brayton cycle

Performance of pumped thermal electricity storage system based on reverse/forward Brayton cycle

Can Facebook likes predict the purchase probability of electricity storage systems?

This study among owners of photovoltaic systems investigates whether users' Big Five personality traits derived from their Facebook likes contribute to whether or not they adopt an electricity storage. It is based on the finding that the digital footprint, especially the Facebook likes, can in part predict the personality of users better than friends and family. The survey was conducted among 159 Facebook users in Germany who owned a photovoltaic system. For comparison, a control sample with data from the German Socio-Economic Panel with 425 photovoltaic owners among 7286 individuals was used. The results show that, for extraversion, agreeableness, and neuroticism, the mean scores could be sufficiently predicted. However, a positive correlation could only be detected for extraversion. The comparison of the user groups could not provide satisfying results. None of the Big Five personality traits could be used to distinguish the two user groups from each other. Although the results did not support the hypotheses, this study offers insights into the possibilities of combining data mining, personality psychology, and consumer research.

Separating Nuclear Reactors from the Power Block with Heat Storage to Improve Economics with Dispatchable Heat and Electricity

Markets are changing as the result of (1) the addition of variable wind and solar that causes highly volatile electricity prices and (2) the goal of a low-carbon economy. These changes require economic low-carbon dispatchable electricity, which is now provided by natural gas turbines, and dispatchable heat for industry and commerce. Moreover, nuclear plant requirements have changed in the last 50 years with high capital costs in western countries. An alternative plant design is described with the nuclear island separated from a nonnuclear power block by large-scale heat storage. All heat from the reactor is sent to heat storage. The nuclear reactor operates at base load and is sized to meet average energy demand over a period of days. Heat storage provides variable heat to industry and/or the power block. The nonnuclear power block is sized to provide peak electricity capacity (kilowatts) several times the nuclear reactor base-load power output to maximize revenue by sale of electricity at times of high prices. The power block capital cost (heat exchanger, turbine, and generator) per unit of generating capacity (kilowatt) is less than a conventional gas turbine that includes heat generation (compressor and burner) and the power block (turbine and generator). Nuclear reactor capital cost is reduced by fewer requirements on the nuclear system (not connected to the grid) and nuclear-quality construction for only the reactor. Operating costs (security, maintenance, etc.) are minimized by separation of the nuclear reactor plant from balance of plant. Low-cost heat storage provides a competitive economic advantage to heat-generating technologies (nuclear, concentrated solar power) over electricity-generating technologies (wind, solar, photovoltaic) with more-expensive battery or other electricity storage systems in providing dispatchable electricity to the grid.