Conventional Energy Storage Systems Research Articles

Semi-coherent cation-rich Mn-Cu oxides heterostructures as cathode for novel aqueous potassium dual-ion energy storage devices

In this work, combining both advantages of aqueous energy storage systems (ESS) and conventional dual-ion ESS, a novel aqueous dual-ion ESS is developed based on K+ and OH– electrochemistry by employing semi-coherent K1.33Mn8O16-CuO (sc–Mn–Cu) cathode. Profting from the elaborate design, the electrolyte and cathode simultaneously act as source of cations. In the novel aqueous dual-ion ESS configuration, the dependence of the performance on the electrolyte salt concentration is reduced and the sc–Mn–Cu cathode can host OH− with lower working potentials by conversion mechanism. Furthermore, based on the sc–Mn–Cu cathode and freestanding V2O3–VC (fs-V2O3–VC) anode, we developed a flexible quasi-solid-state device. Remarkably, it exhibits an ultrahigh energy density of ~39.9 μW h cm−2 together with high power density of carbon-based devices, which outperforms most previously reported flexible storage devices to our knowledge. These results indicating that the unique mechanism of the sc–Mn–Cu cathode opens up a promising direction for low-cost and high-performance novel aqueous ESS.

Sizing Scheme of Hybrid Energy Storage System for Electric Vehicle

Energy storage system (batteries) plays a vital role in the adoption of electric vehicles (EVs). Li-ion batteries have high energy storage-to-volume ratio, but still, it should not be charged/discharged for short periods frequently as it results in degradation of their state of health (SoH). To resolve this issue, a conventional energy storage system (ESS) is being replaced by hybrid ESS (HESS). The requirement of high-voltage energy sources is increasing with the increasing number of performance based EVs. High-voltage storages are usually difficult to design due to the involvement of higher rating devices; hence, there is a need to create a method to modularize the storage. Modularization can be implemented using lower rating converters to decouple the ultra-capacitors (UCs) and batteries from the load, reducing the cost of storage. This article proposes a fully active series–parallel HESS topology which uses a set of UCs deployed in conjunction with the batteries. UCs provide the advantage of quick and frequent charging/discharging without degrading the battery SoH and are also used to absorb most of the energy generated due to regenerative braking. The major source of energy is Li-ion cells which provide the energy required to run the vehicle, whereas the UCs will provide above-average energy required by the motor. The proposed topology is managed by rule-based energy management systems (EMS), which considers pre-decided threshold parameters of various storage devices. Firstly, a power-based method to find the specifications of UCs and batteries is described which provides specifications for ESS hybridization. The proposed method, which is based on the prescribed set of limiting values of current and voltages, tries to maintain the UC voltage and battery current within range. This method reduces the above-average peaks of the required current from the batteries. Similarly, while recharging due to the regenerative braking, the proposed method removes the above-average peaks of the charging current of UCs. The proposed topology along with the EMS provides better state of charge (SoC) levels, giving a 38.6% increase in SoH levels of the batteries.

Stability Analysis of Sampled-Data Load Frequency Control Systems With Multiple Delays

The load frequency control (LFC) system equipped with communication networks includes both sampled-data and time-delay characteristics. How to consider both characteristics effectively in stability analysis is of great importance to obtain accurate results. In this brief, we investigate the delay-dependent stability of sampled-data systems with multiple delays by separately considering the effects of sampling and delays. We first build a discrete-time model for an LFC system with both conventional units and energy storage systems, where the effect of time-varying delays is modeled as matrix uncertainty. Based on this model, we propose a stability criterion for delay margin computation using the region-division technique. A heuristic algorithm is further developed to enhance the computational efficiency and accuracy of the proposed criterion. Case studies are carried out to show the effectiveness and advantages of the proposed method.

Sizing and Siting of Distributed Cloud Energy Storage Systems for a Shipboard Power System

The research on ship electrification is gaining renewed interest to take advantage of the numerous benefits offered by microgrids in the development of an all-electric ship (AES). A key aspect of the AES is in planning of cost effective and resilient shipboard power system (SPS). The integration of energy storage system (ESS) in SPS is found to help achieve this goal. An ESS can improve the fuel economy of diesel generators by regulating their load demand and provide emergency power promptly whenever necessary. This article proposes a planning strategy for sizing and siting of a special ESS integration configuration, distributed cloud ESS (DCESS), in the SPS. While the aim of DCESS sizing is minimizing the total cost of SPS, the objective of DCESS siting is to enhance the resilience of SPS. By stochastic programming, the optimal solution with respect to representative operating conditions and fault scenarios is obtained. The proposed DCESS configuration would facilitate easy power exchange among the electrical zones. A comparison with the conventional ESS configuration is presented and the benefit of DCESS configuration on resilience enhancement is demonstrated.

Cooperative control strategy for distributed wind-storage combined system based on consensus protocol

To realize real-time wind farm output power regulation with power-sharing among storage devices that have different state of charges (SoCs), this paper proposes the cooperative control of the distributed wind-storage combined systems (WSCSs). It firstly establishes the mathematical model of doubly-fed induction generator (DFIG) and hybrid energy storage system (HESS) and implements the controls for two devices, respectively. Secondly, based on the power consensus protocol, an active power cooperative control strategy of the distributed WSCSs is proposed. It ensures that the energy storage devices can cooperatively compensate for wind power according to their different capacities to regulate the output power of the wind farm (WF) in real-time. At the same time, the high- and low- frequency power fluctuations can be effectively shared by the supercapacitors (SCs) and batteries, overcoming the deficiencies of the conventional battery energy storage system (BESS). Then, considering that the SoCs of the batteries are not identical, this paper further proposes a DFIG grid-side reference power adjustment strategy based on consensus protocol. It guarantees that each HESS can effectively achieve power-sharing while regulating the output power according to the SoCs of batteries. Finally, simulations in PSCAD/EMTDC under various scenarios are conducted to demonstrate the effectiveness of the proposed control strategy.

LOAD FREQUENCY CONTROL FOR AN ISOLATED HYBRID POWER SYSTEM WITH HYBRID CONTROL TECHNIQUE AND COMPARATIVE ANALYSIS WITH DIFFERENT CONTROL TECHNIQUES

This paper presents a hybrid isolated power system modeling and Load Frequency Controller (LFC) for different penetration levels of wind power generation. The system considered here consists of a conventional diesel generator, wind generator and energy storage system for a LFC. The purpose of the considered system is to suppress the frequency deviations (balancing the real power generation and demand). An inertia control is used to obtain the best possible gain of the wind system and Fuzzy Logic Control (FLC) is used to control the frequency of the hybrid system. The results are compared with different control techniques. The dynamic performance of the system is studied at different cases by changing the wind penetration level and also by increasing the load disturbances.

Multi-Energy School System for Seasonal Use in the Mediterranean Area

School buildings represent an energy-consuming sector of real estate where different efficiency actions are necessary. The literature shows how the design of a multi-energy system offers numerous advantages, however, there are problems related to the integration of cogeneration units with renewable energy sources due to the low flexibility of the first one and the high degree of uncertainty of the latter. The authors provide an alternative solution through the analysis of a case study consisting of a multiple energy system in three Sicilian schools, focusing on the system’s operational strategy, on the design and sizing of components and trying to exploit the energy needs complementarity of buildings instead of integrating the conventional energy storage systems. Not considering school activities in summer, it was decided to install a cogeneration unit sized on winter thermal loads, whereas the electricity demand not covered was reduced with photovoltaic systems designed to maximize production for seasonal use and with loads concentrated in the morning hours. The effectiveness of this idea, which can be replicated for similar users and areas, is proved by a payback time of less than 11 years and a reduction of 31.77% of the CO2 emissions.

Optimal operation of water-energy microgrids; a mixed integer linear programming formulation

Increasing energy efficiency in water distribution systems is one of the most important aspects of a sustainable water infrastructure. Additionally, providing this energy from renewable sources is an essential step towards a cleaner production in energy infrastructures. Therefore in this paper, an optimization model is developed to minimize the energy consumption of a water-energy microgrid system. A day-ahead economic dispatch model is developed to minimize the daily cost of energy in the water-energy microgrid. The energy consumption of water system is minimized using tank’s and pump’s scheduling and operation, hydraulic factors, and daily demand. Particularly, the electricity consumption of the pump is minimized by adjusting its head gain and flow rate via a variable speed. The energy unit is composed of an aggregated conventional power generation, solar photovoltaic, wind generation, and battery energy storage system. To offer a global optimum for the proposed non-linear programming formulation, bivariate piecewise linear approximation is used to linearize the pump’s power consumption and gain, and conservation of energy-mass. In addition, univariate piecewise linear approximation is used to linearize the energy consumption function of conventional power generation systems. The optimization results of the mixed integer linear programming and mixed integer non-linear programming formulations for the studied water-energy microgrid system are compared and discussed. These models are developed to concurrently minimize the electricity consumption of a micro water-energy distribution network in two scenarios of (1) standalone water distribution system operation and (2) an integrated islanded micro water-energy system with electrical loads.

Energy performance of seasonal thermal energy storage in underground backfilled stopes of coal mines

Thermal storage of the energy is essential for district heating systems to mitigate intermittency related issues. The extensive cavities created after extraction of ores/coal in mines could provide a unique opportunity for storage and extraction of thermal energy. This paper shows that underground backfilled stopes present a viable potential for being retrofitted to thermal energy storage batteries. The present study evaluates the energy performance of thermal energy storage in underground backfilled stopes by installing heat exchange tubes prior to backfill placement. A numerical fluid mechanics and heat transfer model for backfill stopes was developed in Fluent to investigate the heat exchange inside the tubes as well as the heat transfer happening within the backfill during the heat storage and extraction process. The proposed model is compared against an analytical heat transfer model to determine its reliability and accuracy. The results obtained from the validated numerical model showed that energy storage system in a typical underground backfilled stope of coal mines can provide about 23 GWh of thermal energy storage capacity with an average recovery rate of 60% during extraction cycles. Accordingly, several sensitivity analyses were conducted to define the optimum center-to-center distance for the pipe installation to attain the best system performance. Through a series of parametric studies, it was found that thermal conductivity of backfill and rock, circulating fluid mass flow rate, initial rock temperature and thermal saturation time constitute the most significant influencing parameters on energy storage performance of such applications. It can be concluded that thermal energy storage systems in backfilled stopes are relatively more techno-economically feasible, compared to conventional borehole energy storage systems, in terms of their significantly lower drilling/installation costs and higher hosting temperature.

Advancing Flexible Thermoelectric Devices with Polymer Composites

AbstractThe booming of flexible electronics calls for consistent and reliable power supply. Compared to conventional energy storage systems which require frequent recharge, replacement, and maintenance, thermoelectric (TE) devices that directly convert heat into electricity exhibit desirable features including no noise, no vibration, no gas emission, and long lifetime, thus favoring the miniaturization and integrity of current flexible electronics. TE polymer composites are especially attractive as they combine the merits of both polymers and filler materials, which results in high TE performance as well as superior flexibility, thereby demonstrating high potential for flexible TE devices. Herein, some fundamental basics regarding polymer composites are presented and then recent progresses of various polymer composites based on the category of filler materials are summarized so that research efforts and results can be better comprehended. Subsequently, effective strategies to further strengthen the TE performance of polymer composites are emphasized. The following section introduces recent design prototypes of flexible TE devices based on polymer composites with rational discussion on the characteristics of each design. Finally, the remaining challenges with future research perspectives are proposed in conclusion.

Experimental tests to validate the simulation model of a Domestic Trigeneration Scheme with hybrid RESs and Desalting Techniques

Experimental tests of a small polygeneration plant unit based on hybrid renewable energy and desalination have been used to validate a novel model simulation of this plant. It provides electricity by coupling photovoltaic/thermal collectors and a micro-wind turbine, fresh water by means of hybrid desalination (membrane distillation, and reverse osmosis), and sanitary hot water coming from the photovoltaic/thermal collectors and an evacuated tubes collector. Plant was designed to operate in off-grid conditions and conventional energy storage systems were used (lead acid batteries and hot water tank). Simulation model was performed in TRNSYS environment and it was fully validated by comparing several key plant measurements. The analysis was focused on five typical days of summer, fall and winter. Some differences found in experimental and simulated values were analysed. To reduce those gaps, some modifications have been suggested to the model or the pilot unit respectively. As a result, a validated model in TRNSYS of the plant was obtained. This model can be used for the further scale up of new projects to cover any other scheduled demands of power and water in isolated areas, whenever is based on the combination of the abovementioned technologies.

Demand-Side Management With Shared Energy Storage System in Smart Grid

Energy storage systems (ESSs) have been considered to be an effective solution to reduce the spatial and temporal imbalance between the stochastic energy generation and the demand. To effectively utilize an ESS, an approach of jointly sharing and operating an ESS has been proposed in a conceptual way. However, there is a lack of analytic approaches designed to optimize the operation of such a system considering interactions among users in a game theoretic perspective. In this study, we propose the energy capacity trading and operation (ECTO) game where each agent determines two actions, capacity trading, and the 24-hour ahead charging-discharging scheduling with the capacity that will be assigned, to minimize the energy operation cost. We then propose a distributed optimization strategy to find a generalized Nash equilibrium for the proposed ECTO game. Simulation studies show that when optimally operated, a shared ESS can decrease both the total energy operating cost and the peak-to-average ratio of the energy for the entire grid compared to the conventional ESS control strategy without ESS sharing.

Reducing Distribution Power Loss of Islanded AC Microgrids Using Distributed Electric Springs With Predictive Control

Recently proposed electric springs (ESs), as alternatives to conventional energy storage systems, are used to regulate bus voltages of ac microgrids with few or even no battery packs. Pioneering works have demonstrated the merits of ES in reducing the infrastructure and maintenance costs of expensive battery packs while still improving the power quality, stability, and dynamic responses of microgrids. However, distribution power loss reduction of islanded ac microgrids by controlling distributed ES has never been investigated. The major novel contribution of this article is to extend the function of ES, along with emerging high-speed communication techniques, to enhance the rate of energy utilization in islanded ac microgrids. A predictive control in the power flow router calculates and feeds the optimal bus voltage references to each ES, which in turn controls the respective distribution power flow based on real-time power measurements. This allows the distributed ES to mitigate the overall distribution power loss of the islanded ac microgrid. Simulation results verified the significant power loss reductions in various structures of islanded ac microgrids with the distributed ES under the proposed predictive control. Experimental results also validate the effectiveness of the distributed ES operating under the predictive control in reducing the distribution power loss of a 3-bus and a 5-bus islanded ac microgrid.

Environmental feasibility of secondary use of electric vehicle lithium-ion batteries in communication base stations

Repurposing spent batteries in communication base stations (CBSs) is a promising option to dispose massive spent lithium-ion batteries (LIBs) from electric vehicles (EVs), yet the environmental feasibility of this practice remains unknown. Life cycle assessment (LCA) is used in this study to compare the environmental impacts of repurposed EV LIBs and lead-acid batteries (LABs) used in conventional energy storage systems (ESSs) of CBSs. The economic-based allocation method is used in the multi-functional system. The LCA results suggest that the manufacturing and reusing stages are the dominant contributors to the environmental impacts of repurposed LIBs, whereas battery recycling can reduce environmental impacts. In addition, the secondary use of EV LIBs results in less environmental impact than the use of LABs in all selected categories, except for metal depletion, which is attributed to the large lead consumption and low energy density of LABs. A sensitivity analysis is conducted to measure the influences of two alternative allocation methods (i.e., cut-off allocation and 50/50 allocation), the cycle life, and the electricity sources on the results. It is found that repurposing spent LIBs with 50/50 allocation method has the poorest environmental performance and is not sufficiently advantageous over using LABs. Moreover, extending the cycle life of repurposed LIBs and using a cleaner energy mix significantly reduce environmental impacts. This study offers implications to mitigate the end-of-life management problem of EV LIBs, including a life cycle management platform, an effective integration of the supply chain, and references for the ongoing “green” transition of the communication industry.

Incorporating flexibility requirements into distribution system expansion planning studies based on regulatory policies

Increasing penetration of renewable energy sources with intermittent generation calls for further flexibility requirements for efficient as well as the safe operation of power systems. Considering the significant growth of distributed energy resources in distribution systems, a promising approach to fulfill such requirements is to deploy local flexibility sources at the distribution level. Nonetheless, due to the monopoly nature of electricity distribution business, effective regulations are required to direct distribution companies toward fulfilling such goals. Accordingly, this paper aims at proposing various policies to motivate distribution companies to enhance the flexibility of their networks. In order to assess the effectiveness of these rules, we present a novel multi-stage distribution expansion planning model considering flexibility requirements. In this model, installation of conventional dispatchable distributed generation units and battery energy storage systems, as well as demand response programs, are considered available flexibility sources for distribution system planners. The proposed framework is applied to a test distribution network with 18 nodes, and the obtained results are thoroughly discussed. Finally, a sensitivity analysis is conducted to assess the effects of the key parameters of the proposed model on expansion planning of the test system.

Reliability Evaluation and Improvement of Islanded Microgrid Considering Operation Failures of Power Electronic Equipment

With the high integration of power electronic technologies in microgrids, the reliability assessment considering power electronic devices has become a hot topic. However, so far no research has considered the impact of the operation failure probability of power electronic equipment on the overall reliability of the microgrid. This paper aims to construct a holistic operation failure rate model of power electronic systems based on the overall reliability assessment of islanded microgrid with high penetration of renewable energy sources (RESs). In addition, to improve the reliability of islanded microgrid, the conventional battery energy storage system (BESS) is replaced by the hybrid energy storage system (HESS). Based on the proposed model, the operation failure models for the power electronic modules in microgrid are built and tested, and then the sensitivity analysis is performed for exploring the influence of various factors on the reliability of the microgrid.

Performance Analysis of a Solar DHW System with Adsorption Module Operating in Different World Locations

A numerical study was conducted on the performance of a solar domestic hot water storage system with an adsorption module operating in seven different world locations. The base system was optimized for Portuguese conditions and, without changing the system itself and the water consumption profile, its performance was investigated by altering local installation and operating conditions and solar collector inclination angles. The overall dynamical model of the system was used for numerical simulations. The improved performance of the system was assessed by the reduction achieved on the annual energy consumption of a backup water heater when compared with a similar conventional energy storage system (without an adsorption module). The results showed that the best performances were obtained in locations where winter and summer are clearly defined, especially locations where winters are colder, and with solar collectors’ inclination angles larger than the local latitude, except for locations with low latitudes, where solar collectors’ inclination angles are not so relevant to the system performance. It was also discussed how the performance results must be carefully analyzed, as for low-latitude locations the absolute savings are in fact smaller even if their relative values are of the same order or even higher than for higher-latitude locations.

Development of a high-energy-density portable/mobile hydrogen energy storage system incorporating an electrolyzer, a metal hydride and a fuel cell

A hydrogen energy storage system for portable/mobile applications such as personal power sources and unmanned underwater vehicles is developed. An application-oriented design and system integration strategy are newly suggested to maximize energy density while incorporating conventional technologies for the electrolyzer (Ely), the metal hydride (MH), and the polymer electrolyte membrane fuel cell (PEMFC). To improve both the energy density and usability, the systems for charging and discharging are separated. The charging component is composed of a water Ely (0.5 Nm3 h−1) and an MH cooling device as one system. The discharging component consists of an MH (900 NL H2), a PEMFC stack (50 W), and a power conditioning system (PCS) as a single system. The MH material and engineering properties are investigated to find an MH that is suitable for the target system. The hybrid design and operating strategy of the PEMFC and PCS are developed to maximize energy density. The prototype system provides a nominal power output of 31.5 W at 12 V for 38 h with one recharging. We find it significant that the discharging component shows an energy density of 410 Wh L−1, which is twice that of conventional energy storage systems at the 2.9-L level.

Modeling and Comparative Analysis of the Conventional and Hybrid Energy Storage Systems used in Electric Vehicular Technology

Modeling and Comparative Analysis of the Conventional and Hybrid Energy Storage Systems used in Electric Vehicular Technology

Improved Electrolyte for Negative Side of Zinc-Cerium Redox Flow Batteries

Redox flow batteries (RFBs) are one of the most recent and promising technologies for large-scale energy storage applications. In an RFB, the active materials for the two redox reactions are dissolved in separate electrolytes stored in external tanks. During charge/discharge, these electrolytes are pumped through the cell where the redox reactions occur. Compared to conventional energy storage systems, RFBs are advantageous due to their portability, low maintenance cost, modularity and flexibility [1]. RFBs based on zinc-cerium chemistry are very attractive since they provide the highest cell voltage among flow batteries and thus the highest theoretical energy density [2]. Nevertheless, this system has a number of challenges, the most important of which is the occurrence of side reactions. During charge, hydrogen and oxygen evolution side reactions occur at the negative and positive electrodes, respectively, leading to a lower charge efficiency, wasted energy and eventual premature battery failure [3,4]. During discharge, self-discharge of the zinc deposit due to acid attack also contributes to reduction in the efficiency. Thus, the suppression of these side reactions is necessary for the improvement and ultimate success of zinc-cerium RFBs. Toward this goal, our work focuses on the enhancement of the Zn/Zn(II) redox reaction through the use of a mixed-acid electrolyte. From half-cell experiments on a glassy carbon electrode, we have shown that the introduction of 0.2 – 0.3 mol dm−3 of chloride anions to the conventional methanesulfonic acid electrolyte significantly increases the transport properties of Zn(II), reduces the zinc nucleation overpotential and enhances the exchange current density of the Zn/Zn(II) redox reaction [5]. The same effect is observed when glassy carbon is replaced by polyvinyl ester (PVE), which is a commonly-used negative electrode in Zn-Ce RFBs. The use of this improved electrolyte on the charge, voltage and energy efficiency of a bench-scale zinc-cerium RFB has also been investigated. Similar to results obtained in the half-cell studies, the full-cell experiments show that the mixed methanesulfonate-chloride electrolyte facilitates the zinc redox reaction and thus increases the voltage efficiency of the battery as high as 10%. Additionally, the charge efficiency increases significantly under the conditions where negative half-cell is the limiting reaction. The improvement is more than 20% at an operating current density of 25 mA cm-2. The performance and life-cycle analysis of the battery with this new electrolyte under different operating conditions will also be discussed in this presentation. [1] De Leon, C. P., Frías-Ferrer, A., González-García, J., Szánto, D. A., & Walsh, F. C. (2006). Redox flow cells for energy conversion. Journal of power sources, 160(1), 716-732. [2] Walsh, F. C., Ponce de Léon, C., Berlouis, L., Nikiforidis, G., Arenas‐Martínez, L. F., Hodgson, D., & Hall, D. (2015). The development of Zn–Ce hybrid redox flow batteries for energy storage and their continuing challenges. ChemPlusChem, 80(2), 288-311. [3] Leung, P. K., Ponce-de-León, C., Low, C. T. J., & Walsh, F. C. (2011). Zinc deposition and dissolution in methanesulfonic acid onto a carbon composite electrode as the negative electrode reactions in a hybrid redox flow battery. Electrochimica Acta, 56(18), 6536-6546. [4] Nikiforidis, G., Berlouis, L., Hall, D., & Hodgson, D. (2014). An electrochemical study on the positive electrode side of the zinc–cerium hybrid redox flow battery. Electrochimica Acta, 115, 621-629. [5] Amini, K., & Pritzker, M. D. (2018). Electrodeposition and electrodissolution of zinc in mixed methanesulfonate-based electrolytes. Electrochimica Acta, 268, 448-461.